Add package dependencies and project settings page

Package Dependencies:
- Add artifact dependency management system
- Add dependency API endpoints (get, resolve, reverse)
- Add ensure file parsing for declaring dependencies
- Add circular dependency and conflict detection
- Add frontend dependency visualization with graph modal
- Add migration for artifact_dependencies table

Project Settings Page (#65):
- Add dedicated settings page for project admins
- General settings section (description, visibility)
- Access management section (moved from project page)
- Danger zone with inline delete confirmation
- Add Settings button to project page header

.gitlab-ci.yml

@@ -8,6 +8,17 @@ variables:
   PROSPER_VERSION: v0.64.1
   # Use internal PyPI proxy instead of public internet
   PIP_INDEX_URL: https://deps.global.bsf.tools/artifactory/api/pypi/pypi.org/simple
+  # Environment URLs (used by deploy and test jobs)
+  STAGE_URL: https://orchard-stage.common.global.bsf.tools
+  PROD_URL: https://orchard.common.global.bsf.tools
+  # Stage environment AWS resources (used by reset job)
+  STAGE_RDS_HOST: orchard-stage.cluster-cvw3jzjkozoc.us-gov-west-1.rds.amazonaws.com
+  STAGE_RDS_DBNAME: postgres
+  STAGE_SECRET_ARN: "arn:aws-us-gov:secretsmanager:us-gov-west-1:052673043337:secret:rds!cluster-a573672b-1a38-4665-a654-1b7df37b5297-IaeFQL"
+  STAGE_S3_BUCKET: orchard-artifacts-stage
+  AWS_REGION: us-gov-west-1
+  # Shared pip cache directory
+  PIP_CACHE_DIR: "$CI_PROJECT_DIR/.pip-cache"
 
 # Prevent duplicate pipelines for MRs
 workflow:
@@ -25,15 +36,110 @@ stages:
   - analyze
   - deploy
 
+# Override Prosper template jobs to exclude tag pipelines
+# Tags only run deploy_prod and smoke_test_prod (image already built on main)
+build_image:
+  rules:
+    - if: '$CI_COMMIT_TAG'
+      when: never
+    - when: on_success
+
+test_image:
+  rules:
+    - if: '$CI_COMMIT_TAG'
+      when: never
+    - when: on_success
+
+hadolint:
+  rules:
+    - if: '$CI_COMMIT_TAG'
+      when: never
+    - when: on_success
+
 kics:
   variables:
     KICS_CONFIG: kics.config
+  rules:
+    - if: '$CI_COMMIT_TAG'
+      when: never
+    - when: on_success
 
-# Post-deployment integration tests template
+secrets:
+  rules:
+    - if: '$CI_COMMIT_TAG'
+      when: never
+    - when: on_success
+
+app_deps_scan:
+  rules:
+    - if: '$CI_COMMIT_TAG'
+      when: never
+    - when: on_success
+
+cve_scan:
+  rules:
+    - if: '$CI_COMMIT_TAG'
+      when: never
+    - when: on_success
+
+app_sbom_analysis:
+  rules:
+    - if: '$CI_COMMIT_TAG'
+      when: never
+    - when: on_success
+
+cve_sbom_analysis:
+  rules:
+    - if: '$CI_COMMIT_TAG'
+      when: never
+    - when: on_success
+
+# Override release job to wait for stage integration tests before creating tag
+# This ensures the tag (which triggers prod deploy) is only created after stage passes
+release:
+  needs: [integration_test_stage, changelog]
+
+# Full integration test suite template (for feature/stage deployments)
+# Runs the complete pytest integration test suite against the deployed environment
 .integration_test_template: &integration_test_template
   stage: deploy  # Runs in deploy stage, but after deployment due to 'needs'
   image: deps.global.bsf.tools/docker/python:3.12-slim
-  timeout: 10m
+  timeout: 20m  # Full suite takes longer than smoke tests
+  interruptible: true  # Cancel if new pipeline starts
+  retry: 1  # Retry once on failure (network flakiness)
+  cache:
+    key: pip-$CI_COMMIT_REF_SLUG
+    paths:
+      - .pip-cache/
+    policy: pull-push
+  before_script:
+    - pip install --index-url "$PIP_INDEX_URL" -r backend/requirements.txt
+    - pip install --index-url "$PIP_INDEX_URL" pytest pytest-asyncio httpx
+  script:
+    - cd backend
+    # Run full integration test suite, excluding:
+    # - large/slow tests
+    # - requires_direct_s3 tests (can't access MinIO from outside K8s cluster)
+    # ORCHARD_TEST_URL tells the tests which server to connect to
+    # Note: Auth tests work because dev/stage deployments have relaxed rate limits
+    - |
+      python -m pytest tests/integration/ -v \
+        --junitxml=integration-report.xml \
+        -m "not large and not slow and not requires_direct_s3" \
+        --tb=short
+  artifacts:
+    when: always
+    expire_in: 1 week
+    paths:
+      - backend/integration-report.xml
+    reports:
+      junit: backend/integration-report.xml
+
+# Lightweight smoke test template (for production - no test data creation)
+.smoke_test_template: &smoke_test_template
+  stage: deploy
+  image: deps.global.bsf.tools/docker/python:3.12-slim
+  timeout: 5m
   before_script:
     - pip install --index-url "$PIP_INDEX_URL" httpx
   script:
@@ -43,12 +149,12 @@ kics:
       import os
       import sys
 
-      BASE_URL = os.environ.get("BASE_URL")
+      BASE_URL = os.environ.get("ORCHARD_TEST_URL")
       if not BASE_URL:
-          print("ERROR: BASE_URL not set")
+          print("ERROR: ORCHARD_TEST_URL not set")
           sys.exit(1)
 
-      print(f"Running integration tests against {BASE_URL}")
+      print(f"Running smoke tests against {BASE_URL}")
       client = httpx.Client(base_url=BASE_URL, timeout=30.0)
 
       errors = []
@@ -86,49 +192,138 @@ kics:
               print(f"  FAIL: {e}")
           sys.exit(1)
       else:
-          print("SUCCESS: All integration tests passed!")
+          print("SUCCESS: All smoke tests passed!")
           sys.exit(0)
       PYTEST_SCRIPT
 
-# Integration tests for stage deployment
-integration_test_stage:
-  <<: *integration_test_template
-  needs: [deploy_stage]
-  variables:
-    BASE_URL: https://orchard-stage.common.global.bsf.tools
+# Integration tests for stage deployment (full suite)
+# Reset stage template - shared by pre and post test reset jobs
+# Calls the /api/v1/admin/factory-reset endpoint which handles DB and S3 cleanup
+.reset_stage_template: &reset_stage_template
+  stage: deploy
+  image: deps.global.bsf.tools/docker/python:3.12-slim
+  timeout: 5m
+  retry: 1  # Retry once on transient failures
+  before_script:
+    - pip install --index-url "$PIP_INDEX_URL" httpx
+  script:
+    - |
+      python - <<'RESET_SCRIPT'
+      import httpx
+      import sys
+      import os
+      import time
+
+      BASE_URL = os.environ.get("STAGE_URL", "")
+      ADMIN_USER = "admin"
+      ADMIN_PASS = "changeme123"  # Default admin password
+      MAX_RETRIES = 3
+      RETRY_DELAY = 5  # seconds
+
+      if not BASE_URL:
+          print("ERROR: STAGE_URL environment variable not set")
+          sys.exit(1)
+
+      print(f"=== Resetting stage environment at {BASE_URL} ===")
+
+      def do_reset():
+          with httpx.Client(base_url=BASE_URL, timeout=120.0) as client:
+              # Login as admin
+              print("Logging in as admin...")
+              login_response = client.post(
+                  "/api/v1/auth/login",
+                  json={"username": ADMIN_USER, "password": ADMIN_PASS},
+              )
+              if login_response.status_code != 200:
+                  raise Exception(f"Login failed: {login_response.status_code} - {login_response.text}")
+              print("Login successful")
+
+              # Call factory reset endpoint
+              print("Calling factory reset endpoint...")
+              reset_response = client.post(
+                  "/api/v1/admin/factory-reset",
+                  headers={"X-Confirm-Reset": "yes-delete-all-data"},
+              )
+
+              if reset_response.status_code == 200:
+                  result = reset_response.json()
+                  print("Factory reset successful!")
+                  print(f"  Database tables dropped: {result['results']['database_tables_dropped']}")
+                  print(f"  S3 objects deleted: {result['results']['s3_objects_deleted']}")
+                  print(f"  Database reinitialized: {result['results']['database_reinitialized']}")
+                  print(f"  Seeded: {result['results']['seeded']}")
+                  return True
+              else:
+                  raise Exception(f"Factory reset failed: {reset_response.status_code} - {reset_response.text}")
+
+      # Retry loop
+      for attempt in range(1, MAX_RETRIES + 1):
+          try:
+              print(f"Attempt {attempt}/{MAX_RETRIES}")
+              if do_reset():
+                  sys.exit(0)
+          except Exception as e:
+              print(f"Attempt {attempt} failed: {e}")
+              if attempt < MAX_RETRIES:
+                  print(f"Retrying in {RETRY_DELAY} seconds...")
+                  time.sleep(RETRY_DELAY)
+              else:
+                  print("All retry attempts failed")
+                  sys.exit(1)
+      RESET_SCRIPT
   rules:
     - if: '$CI_COMMIT_BRANCH == "main"'
       when: on_success
 
-# Integration tests for feature deployment
+# Reset stage BEFORE integration tests (ensure known state)
+reset_stage_pre:
+  <<: *reset_stage_template
+  needs: [deploy_stage]
+
+# Integration tests for stage deployment (full suite)
+integration_test_stage:
+  <<: *integration_test_template
+  needs: [reset_stage_pre]
+  variables:
+    ORCHARD_TEST_URL: $STAGE_URL
+  rules:
+    - if: '$CI_COMMIT_BRANCH == "main"'
+      when: on_success
+
+# Reset stage AFTER integration tests (clean slate for next run)
+reset_stage:
+  <<: *reset_stage_template
+  needs: [integration_test_stage]
+  allow_failure: true  # Don't fail pipeline if reset has issues
+
+# Integration tests for feature deployment (full suite)
 integration_test_feature:
   <<: *integration_test_template
   needs: [deploy_feature]
   variables:
-    BASE_URL: https://orchard-$CI_COMMIT_REF_SLUG.common.global.bsf.tools
+    ORCHARD_TEST_URL: https://orchard-$CI_COMMIT_REF_SLUG.common.global.bsf.tools
   rules:
     - if: '$CI_COMMIT_BRANCH && $CI_COMMIT_BRANCH != "main"'
       when: on_success
 
-# Run Python backend tests
-python_tests:
+# Run Python backend unit tests
+python_unit_tests:
   stage: test
   needs: []  # Run in parallel with build
   image: deps.global.bsf.tools/docker/python:3.12-slim
   timeout: 15m
-  variables:
-    PIP_CACHE_DIR: "$CI_PROJECT_DIR/.pip-cache"
+  interruptible: true  # Cancel if new pipeline starts
   cache:
     key: pip-$CI_COMMIT_REF_SLUG
     paths:
       - .pip-cache/
     policy: pull-push
   before_script:
-    - pip install -r backend/requirements.txt
-    - pip install pytest pytest-asyncio pytest-cov httpx
+    - pip install --index-url "$PIP_INDEX_URL" -r backend/requirements.txt
+    - pip install --index-url "$PIP_INDEX_URL" pytest pytest-asyncio pytest-cov httpx
   script:
     - cd backend
-    # Only run unit tests - integration tests require Docker Compose services
+    # Run unit tests (integration tests run post-deployment against live environment)
     - python -m pytest tests/unit/ -v --cov=app --cov-report=term --cov-report=xml:coverage.xml --cov-report=html:coverage_html --junitxml=pytest-report.xml
   artifacts:
     when: always
@@ -143,6 +338,10 @@ python_tests:
         coverage_format: cobertura
         path: backend/coverage.xml
   coverage: '/TOTAL.*\s+(\d+%)/'
+  rules:
+    - if: '$CI_COMMIT_TAG'
+      when: never
+    - when: on_success
 
 # Run frontend tests
 frontend_tests:
@@ -150,6 +349,7 @@ frontend_tests:
   needs: []  # Run in parallel with build
   image: deps.global.bsf.tools/docker/node:20-alpine
   timeout: 15m
+  interruptible: true  # Cancel if new pipeline starts
   cache:
     key: npm-$CI_COMMIT_REF_SLUG
     paths:
@@ -171,11 +371,15 @@ frontend_tests:
         coverage_format: cobertura
         path: frontend/coverage/cobertura-coverage.xml
   coverage: '/All files[^|]*\|[^|]*\s+([\d\.]+)/'
+  rules:
+    - if: '$CI_COMMIT_TAG'
+      when: never
+    - when: on_success
 
 # Shared deploy configuration
 .deploy_template: &deploy_template
   stage: deploy
-  needs: [build_image, kics, hadolint, python_tests, frontend_tests, secrets]
+  needs: [build_image, test_image, kics, hadolint, python_unit_tests, frontend_tests, secrets, app_deps_scan, cve_scan, cve_sbom_analysis, app_sbom_analysis]
   image: deps.global.bsf.tools/registry-1.docker.io/alpine/k8s:1.29.12
 
 .helm_setup: &helm_setup
@@ -184,47 +388,21 @@ frontend_tests:
   # OCI-based charts from internal registry - no repo add needed
   - helm dependency update
 
+# Simplified deployment verification - just health check
+# Full API/frontend checks are done by integration tests post-deployment
 .verify_deployment: &verify_deployment |
   echo "=== Waiting for health endpoint (certs may take a few minutes) ==="
   for i in $(seq 1 30); do
     if curl -sf --max-time 10 "$BASE_URL/health" > /dev/null 2>&1; then
       echo "Health check passed!"
-      break
+      echo "Deployment URL: $BASE_URL"
+      exit 0
     fi
     echo "Attempt $i/30 - waiting 10s..."
     sleep 10
   done
-
-  # Verify health endpoint
-  echo ""
-  echo "=== Health Check ==="
-  curl -sf "$BASE_URL/health" || { echo "Health check failed"; exit 1; }
-  echo ""
-
-  # Verify API is responding
-  echo ""
-  echo "=== API Check (GET /api/v1/projects) ==="
-  HTTP_CODE=$(curl -sf -o /dev/null -w "%{http_code}" "$BASE_URL/api/v1/projects")
-  if [ "$HTTP_CODE" = "200" ]; then
-    echo "API responding: HTTP $HTTP_CODE"
-  else
-    echo "API check failed: HTTP $HTTP_CODE"
-    exit 1
-  fi
-
-  # Verify frontend is served
-  echo ""
-  echo "=== Frontend Check ==="
-  if curl -sf "$BASE_URL/" | grep -q "</html>"; then
-    echo "Frontend is being served"
-  else
-    echo "Frontend check failed"
-    exit 1
-  fi
-
-  echo ""
-  echo "=== All checks passed! ==="
-  echo "Deployment URL: $BASE_URL"
+  echo "Health check failed after 30 attempts"
+  exit 1
 
 # Deploy to stage (main branch)
 deploy_stage:
@@ -232,7 +410,7 @@ deploy_stage:
   variables:
     NAMESPACE: orch-stage-namespace
     VALUES_FILE: helm/orchard/values-stage.yaml
-    BASE_URL: https://orchard-stage.common.global.bsf.tools
+    BASE_URL: $STAGE_URL
   before_script:
     - kubectl config use-context esv/bsf/bsf-integration/orchard/orchard-mvp:orchard-stage
     - *helm_setup
@@ -246,17 +424,17 @@ deploy_stage:
         --set image.tag=git.linux-amd64-$CI_COMMIT_SHA \
         --wait \
         --atomic \
-        --timeout 5m
-    - kubectl rollout status deployment/orchard-stage-server -n $NAMESPACE --timeout=5m
+        --timeout 10m
+    - kubectl rollout status deployment/orchard-stage-server -n $NAMESPACE --timeout=10m
     - *verify_deployment
   environment:
     name: stage
-    url: https://orchard-stage.common.global.bsf.tools
+    url: $STAGE_URL
     kubernetes:
       agent: esv/bsf/bsf-integration/orchard/orchard-mvp:orchard-stage
   rules:
     - if: '$CI_COMMIT_BRANCH == "main"'
-      when: always
+      when: on_success
 
 # Deploy feature branch to dev namespace
 deploy_feature:
@@ -282,8 +460,8 @@ deploy_feature:
         --set minioIngress.tls.secretName=minio-$CI_COMMIT_REF_SLUG-tls \
         --wait \
         --atomic \
-        --timeout 5m
-    - kubectl rollout status deployment/orchard-$CI_COMMIT_REF_SLUG-server -n $NAMESPACE --timeout=5m
+        --timeout 10m
+    - kubectl rollout status deployment/orchard-$CI_COMMIT_REF_SLUG-server -n $NAMESPACE --timeout=10m
     - export BASE_URL="https://orchard-$CI_COMMIT_REF_SLUG.common.global.bsf.tools"
     - *verify_deployment
   environment:
@@ -295,12 +473,14 @@ deploy_feature:
       agent: esv/bsf/bsf-integration/orchard/orchard-mvp:orchard
   rules:
     - if: '$CI_COMMIT_BRANCH && $CI_COMMIT_BRANCH != "main"'
-      when: always
+      when: on_success
 
-# Cleanup feature branch deployment
+# Cleanup feature branch deployment (standalone - doesn't need deploy dependencies)
 cleanup_feature:
-  <<: *deploy_template
+  stage: deploy
   needs: []
+  image: deps.global.bsf.tools/registry-1.docker.io/alpine/k8s:1.29.12
+  timeout: 5m
   variables:
     NAMESPACE: orch-dev-namespace
     GIT_STRATEGY: none  # No source needed, branch may be deleted
@@ -318,3 +498,50 @@ cleanup_feature:
     - if: '$CI_COMMIT_BRANCH && $CI_COMMIT_BRANCH != "main"'
       when: manual
   allow_failure: true
+
+# Deploy to production (version tags only)
+deploy_prod:
+  stage: deploy
+  # For tag pipelines, no other jobs run - image was already built when commit was on main
+  needs: []
+  image: deps.global.bsf.tools/registry-1.docker.io/alpine/k8s:1.29.12
+  variables:
+    NAMESPACE: orch-namespace
+    VALUES_FILE: helm/orchard/values-prod.yaml
+    BASE_URL: $PROD_URL
+  before_script:
+    - kubectl config use-context esv/bsf/bsf-integration/orchard/orchard-mvp:orchard-prod
+    - *helm_setup
+  script:
+    - echo "Deploying to PRODUCTION - version $CI_COMMIT_TAG"
+    - cd $CI_PROJECT_DIR
+    - |
+      helm upgrade --install orchard-prod ./helm/orchard \
+        --namespace $NAMESPACE \
+        -f $VALUES_FILE \
+        --set image.tag=git.linux-amd64-$CI_COMMIT_SHA \
+        --wait \
+        --atomic \
+        --timeout 10m
+    - kubectl rollout status deployment/orchard-prod-server -n $NAMESPACE --timeout=10m
+    - *verify_deployment
+  environment:
+    name: production
+    url: $PROD_URL
+    kubernetes:
+      agent: esv/bsf/bsf-integration/orchard/orchard-mvp:orchard-prod
+  rules:
+    # Only run on semantic version tags (v1.0.0, v1.2.3, etc.)
+    - if: '$CI_COMMIT_TAG =~ /^v\d+\.\d+\.\d+$/'
+      when: on_success
+  allow_failure: false
+
+# Smoke tests for production deployment (read-only, no test data creation)
+smoke_test_prod:
+  <<: *smoke_test_template
+  needs: [deploy_prod]
+  variables:
+    ORCHARD_TEST_URL: $PROD_URL
+  rules:
+    - if: '$CI_COMMIT_TAG =~ /^v\d+\.\d+\.\d+$/'
+      when: on_success

.gitleaks.toml

@@ -0,0 +1,8 @@
+# Gitleaks configuration
+# https://github.com/gitleaks/gitleaks#configuration
+
+[allowlist]
+# Test files that contain variable names matching secret patterns (e.g., s3_key)
+paths = [
+  '''backend/tests/.*\.py''',
+]

.gitleaksignore

@@ -4,6 +4,7 @@
 # False positive: s3_key is an attribute name in test assertions, not a secret
 # These are historical commits - files have since been deleted or updated with inline comments
 7e68baed0886a3c928644cd01aa3b39f92d4f976:backend/tests/test_duplicate_detection.py:generic-api-key:154
+81458b3bcb5ace97109ba4c16f4afa6e55b1b8bd:backend/tests/test_duplicate_detection.py:generic-api-key:154
 2f1891cf0126ec0e7d4c789d872a2cb2dd3a1745:backend/tests/unit/test_storage.py:generic-api-key:381
 10d36947948de796f0bacea3827f4531529c405d:backend/tests/unit/test_storage.py:generic-api-key:381
 bccbc71c13570d14b8b26a11335c45f102fe3072:backend/tests/unit/test_storage.py:generic-api-key:381
@@ -11,3 +12,8 @@ bccbc71c13570d14b8b26a11335c45f102fe3072:backend/tests/unit/test_storage.py:gene
 90bb2a3a393d2361dc3136ee8d761debb0726d8a:backend/tests/unit/test_storage.py:generic-api-key:381
 37666e41a72d2a4f34447c0d1a8728e1d7271d24:backend/tests/unit/test_storage.py:generic-api-key:381
 0cc4f253621a9601c5193f6ae1e7ae33f0e7fc9b:backend/tests/unit/test_storage.py:generic-api-key:381
+35fda65d381acc5ab59bc592ee3013f75906c197:backend/tests/unit/test_storage.py:generic-api-key:381
+08dce6cbb836b687002751fed4159bfc2da61f8b:backend/tests/unit/test_storage.py:generic-api-key:381
+617bcbe89cff9a009d77e4f1f1864efed1820e63:backend/tests/unit/test_storage.py:generic-api-key:381
+1cbd33544388e0fe6db752fa8886fab33cf9ce7c:backend/tests/unit/test_storage.py:generic-api-key:381
+7cfad28f678f5a5b8b927d694a17b9ba446b7138:backend/tests/unit/test_storage.py:generic-api-key:381

CHANGELOG.md

@@ -7,6 +7,107 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 ### Added
+- Added Project Settings page accessible to project admins (#65)
+  - General settings section for editing description and visibility
+  - Access Management section (moved from project page)
+  - Danger Zone section with inline delete confirmation requiring project name
+  - Settings button (gear icon) on project page header for admins
+- Added artifact dependency management system (#76, #77, #78, #79, #80, #81)
+  - `artifact_dependencies` table with version/tag constraints and check constraints
+  - `ArtifactDependency` SQLAlchemy model with indexes for fast lookups
+  - Ensure file parsing (`orchard.ensure` YAML format) during artifact upload
+  - Circular dependency detection at upload time (rejected with 400)
+  - Dependency conflict detection at resolution time (409 with conflict details)
+- Added dependency API endpoints (#78, #79):
+  - `GET /api/v1/artifact/{artifact_id}/dependencies` - Get dependencies by artifact ID
+  - `GET /api/v1/project/{project}/{package}/+/{ref}/dependencies` - Get dependencies by ref
+  - `GET /api/v1/project/{project}/{package}/reverse-dependencies` - Get reverse dependencies (paginated)
+  - `GET /api/v1/project/{project}/{package}/+/{ref}/resolve` - Resolve full dependency tree
+- Added dependency resolution with topological sorting (#79)
+  - Returns flat list of all artifacts needed in dependency order
+  - Includes download URLs, sizes, and version info for each artifact
+- Added frontend dependency visualization (#84, #85, #86):
+  - Dependencies section on package page showing direct dependencies for selected tag
+  - Tag/version selector to switch between artifacts
+  - "Used By" section showing reverse dependencies with pagination
+  - Interactive dependency graph modal with:
+    - Tree visualization with collapsible nodes
+    - Zoom (mouse wheel + buttons) and pan (click-drag)
+    - Click to navigate to package
+    - Hover tooltip with package details
+    - Error display for circular dependencies and conflicts
+- Added migration `008_artifact_dependencies.sql` for dependency schema
+- Added `dependencies.py` module with parsing, validation, and resolution logic
+- Added comprehensive integration tests for all dependency features
+
+### Changed
+- Added pre-test stage reset to ensure known environment state before integration tests (#54)
+- Upload endpoint now accepts optional `ensure` file parameter for declaring dependencies
+- Updated upload API documentation with ensure file format and examples
+
+## [0.5.1] - 2026-01-23
+### Changed
+- Simplified tag pipeline to only run deploy and smoke tests (image already built on main) (#54)
+
+### Fixed
+- Fixed production CI deployment namespace to use correct `orch-namespace` (#54)
+- Added gitleaks config to allowlist test files from secret scanning (#54)
+
+## [0.5.0] - 2026-01-23
+### Added
+- Added factory reset endpoint `POST /api/v1/admin/factory-reset` for test environment cleanup (#54)
+  - Requires admin authentication and `X-Confirm-Reset: yes-delete-all-data` header
+  - Drops all database tables, clears S3 bucket, reinitializes schema, re-seeds default data
+  - CI pipeline automatically calls this after integration tests on stage
+- Added `delete_all()` method to storage backend for bulk S3 object deletion (#54)
+- Added AWS Secrets Manager CSI driver support for database credentials (#54)
+- Added SecretProviderClass template for Secrets Manager integration (#54)
+- Added IRSA service account annotations for prod and stage environments (#54)
+- Added comprehensive upload/download tests for size boundaries (1B to 1GB) (#38)
+- Added concurrent upload/download tests (2, 5, 10 parallel operations) (#38)
+- Added data integrity tests (binary, text, unicode, compressed content) (#38)
+- Added chunk boundary tests for edge cases (#38)
+- Added `@pytest.mark.large` and `@pytest.mark.concurrent` test markers (#38)
+- Added `generate_content()` and `generate_content_with_hash()` test helpers (#38)
+- Added `sized_content` fixture for generating test content of specific sizes (#38)
+- Added upload API tests: upload without tag, artifact creation verification, S3 object creation (#38)
+- Added download API tests: tag: prefix resolution, 404 for nonexistent project/package/artifact (#38)
+- Added download header tests: Content-Type, Content-Length, Content-Disposition, ETag, X-Checksum-SHA256 (#38)
+- Added error handling tests: timeout behavior, checksum validation, resource cleanup, graceful error responses (#38)
+- Added version API tests: version creation, auto-detection, listing, download by version prefix (#38)
+- Added integrity verification tests: round-trip hash verification, client-side verification workflow, size variants (1KB-10MB) (#40)
+- Added consistency check endpoint tests with response format validation (#40)
+- Added corruption detection tests: bit flip, truncation, appended content, size mismatch, missing S3 objects (#40)
+- Added Digest header tests (RFC 3230) and verification mode tests (#40)
+- Added integrity verification documentation (`docs/integrity-verification.md`) (#40)
+- Added conditional request support for downloads (If-None-Match, If-Modified-Since) returning 304 Not Modified (#42)
+- Added caching headers to downloads: Cache-Control (immutable), Last-Modified (#42)
+- Added 416 Range Not Satisfiable response for invalid range requests (#42)
+- Added download completion logging with bytes transferred and throughput (#42)
+- Added client disconnect handling during streaming downloads (#42)
+- Added streaming download tests: range requests, conditional requests, caching headers, download resume (#42)
+- Added upload duration and throughput metrics (`duration_ms`, `throughput_mbps`) to upload response (#43)
+- Added upload progress logging for large files (hash computation and multipart upload phases) (#43)
+- Added client disconnect handling during uploads with proper cleanup (#43)
+- Added upload progress tracking endpoint `GET /upload/{upload_id}/progress` for resumable uploads (#43)
+- Added large file upload tests (10MB, 100MB, 1GB) with multipart upload verification (#43)
+- Added upload cancellation and timeout handling tests (#43)
+- Added comprehensive API documentation for upload endpoints with curl, Python, and JavaScript examples (#43)
+- Added `package_versions` table for immutable version tracking separate from mutable tags (#56)
+  - Versions are set at upload time via explicit `version` parameter or auto-detected from filename/metadata
+  - Version detection priority: explicit parameter > package metadata > filename pattern
+  - Versions are immutable once created (unlike tags which can be moved)
+- Added version API endpoints (#56):
+  - `GET /api/v1/project/{project}/{package}/versions` - List all versions for a package
+  - `GET /api/v1/project/{project}/{package}/versions/{version}` - Get specific version details
+  - `DELETE /api/v1/project/{project}/{package}/versions/{version}` - Delete a version (admin only)
+- Added version support to upload endpoint via `version` form parameter (#56)
+- Added `version:X.Y.Z` prefix for explicit version resolution in download refs (#56)
+- Added version field to tag responses (shows which version the artifact has, if any) (#56)
+- Added migration `007_package_versions.sql` with ref_count triggers and data migration from semver tags (#56)
+- Added production deployment job triggered by semantic version tags (v1.0.0) with manual approval gate (#63)
+- Added production Helm values file with persistence enabled (20Gi PostgreSQL, 100Gi MinIO) (#63)
+- Added integration tests for production deployment (#63)
 - Added GitLab CI pipeline for feature branch deployments to dev namespace (#51)
 - Added `deploy_feature` job with dynamic hostnames and unique release names (#51)
 - Added `cleanup_feature` job with `on_stop` for automatic cleanup on merge (#51)
@@ -16,6 +117,22 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Added internal proxy configuration for npm, pip, helm, and apt (#51)
 
 ### Changed
+- Configured stage and prod to use AWS RDS instead of PostgreSQL subchart (#54)
+- Configured stage and prod to use AWS S3 instead of MinIO subchart (#54)
+- Changed prod deployment from manual to automatic on version tags (#54)
+- Updated S3 client to support IRSA credentials when no explicit keys provided (#54)
+- Changed prod image pullPolicy to Always (#54)
+- Added proxy-body-size annotation to prod ingress for large uploads (#54)
+- CI integration tests now run full pytest suite (~350 tests) against deployed environment instead of 3 smoke tests
+- CI production deployment uses lightweight smoke tests only (no test data creation in prod)
+- CI pipeline improvements: shared pip cache, `interruptible` flag on test jobs, retry on integration tests
+- Simplified deploy verification to health check only (full checks done by integration tests)
+- Extracted environment URLs to global variables for maintainability
+- Made `cleanup_feature` job standalone (no longer inherits deploy template dependencies)
+- Renamed `integration_test_prod` to `smoke_test_prod` for clarity
+- Updated download ref resolution to check versions before tags (version → tag → artifact ID) (#56)
+- Deploy jobs now require all security scans to pass before deployment (added test_image, app_deps_scan, cve_scan, cve_sbom_analysis, app_sbom_analysis to dependencies) (#63)
+- Increased deploy job timeout from 5m to 10m (#63)
 - Added `--atomic` flag to Helm deployments for automatic rollback on failure
 - Adjusted dark mode color palette to use lighter background tones for better readability and reduced eye strain (#52)
 - Replaced project card grid with sortable data table on Home page for better handling of large project lists
@@ -26,6 +143,23 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Improved pod naming: Orchard pods now named `orchard-{env}-server-*` for clarity (#51)
 
 ### Fixed
+- Fixed factory reset not creating default admin user after reset (#60)
+- Admin user was only created at server startup, not after factory reset
+- CI reset job would fail to login because admin user didn't exist
+- Improved reset_stage CI job reliability (#60)
+- Added application-level retry logic (3 attempts with 5s delay)
+- Added job-level retry for transient failures
+- Fixed httpx client to use proper context manager
+- Increased timeout to 120s for reset operations
+- Fixed CI integration test rate limiting: added configurable `ORCHARD_LOGIN_RATE_LIMIT` env var, relaxed to 1000/minute for dev/stage
+- Fixed duplicate `TestSecurityEdgeCases` class definition in test_auth_api.py
+- Fixed integration tests auth: session-scoped client, configurable credentials via env vars, fail-fast on auth errors
+- Fixed 413 Request Entity Too Large errors on uploads by adding `proxy-body-size: "0"` nginx annotation to Orchard ingress
+- Fixed CI tests that require direct S3 access: added `@pytest.mark.requires_direct_s3` marker and excluded from CI
+- Fixed ref_count triggers not being created: added auto-migration for tags ref_count trigger functions
+- Fixed Content-Disposition header encoding for non-ASCII filenames using RFC 5987 (#38)
+- Fixed deploy jobs running even when tests or security scans fail (changed rules from `when: always` to `when: on_success`) (#63)
+- Fixed python_tests job not using internal PyPI proxy (#63)
 - Fixed `cleanup_feature` job failing when branch is deleted (`GIT_STRATEGY: none`) (#51)
 - Fixed gitleaks false positives with fingerprints for historical commits (#51)
 - Fixed integration tests running when deploy fails (`when: on_success`) (#51)
@@ -33,9 +167,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fixed deploy jobs running when secrets scan fails (added `secrets` to deploy dependencies)
 - Fixed dev environment memory requests to equal limits per cluster Kyverno policy
 - Fixed init containers missing resource limits (Kyverno policy compliance)
+- Fixed Python SyntaxWarning for invalid escape sequence in database migration regex pattern
 
 ### Removed
 - Removed unused `store_streaming()` method from storage.py (#51)
+- Disabled PostgreSQL subchart for stage and prod environments (#54)
+- Disabled MinIO subchart for stage and prod environments (#54)
 
 ## [0.4.0] - 2026-01-12
 ### Added

README.md

@@ -22,6 +22,7 @@ Orchard is a centralized binary artifact storage system that provides content-ad
   - **Package** - Named collection within a project
   - **Artifact** - Specific content instance identified by SHA256
 - **Tags** - Alias system for referencing artifacts by human-readable names (e.g., `v1.0.0`, `latest`, `stable`)
+- **Versions** - Immutable version records set at upload time (explicit or auto-detected from filename/metadata), separate from mutable tags
 - **Package Formats & Platforms** - Packages can be tagged with format (npm, pypi, docker, deb, rpm, etc.) and platform (linux, darwin, windows, etc.)
 - **Rich Package Metadata** - Package listings include aggregated stats (tag count, artifact count, total size, latest tag)
 - **S3-Compatible Backend** - Uses MinIO (or any S3-compatible storage) for artifact storage
@@ -73,6 +74,9 @@ Orchard is a centralized binary artifact storage system that provides content-ad
 | `POST` | `/api/v1/project/:project/:package/tags` | Create a tag |
 | `GET` | `/api/v1/project/:project/:package/tags/:tag_name` | Get single tag with artifact metadata |
 | `GET` | `/api/v1/project/:project/:package/tags/:tag_name/history` | Get tag change history |
+| `GET` | `/api/v1/project/:project/:package/versions` | List all versions for a package |
+| `GET` | `/api/v1/project/:project/:package/versions/:version` | Get specific version details |
+| `DELETE` | `/api/v1/project/:project/:package/versions/:version` | Delete a version (admin only) |
 | `GET` | `/api/v1/project/:project/:package/artifacts` | List artifacts in package (with filtering) |
 | `GET` | `/api/v1/project/:project/:package/consumers` | List consumers of a package |
 | `GET` | `/api/v1/artifact/:id` | Get artifact metadata with referencing tags |
@@ -93,12 +97,14 @@ For large files, use the resumable upload API:
 
 When downloading artifacts, the `:ref` parameter supports multiple formats:
 
-- `latest` - Tag name directly
-- `v1.0.0` - Version tag
+- `latest` - Implicit lookup (checks version first, then tag, then artifact ID)
+- `v1.0.0` - Implicit lookup (version takes precedence over tag with same name)
+- `version:1.0.0` - Explicit version reference
 - `tag:stable` - Explicit tag reference
-- `version:2024.1` - Version reference
 - `artifact:a3f5d8e12b4c6789...` - Direct SHA256 hash reference
 
+**Resolution order for implicit refs:** version → tag → artifact ID
+
 ## Quick Start
 
 ### Prerequisites
@@ -230,9 +236,16 @@ curl "http://localhost:8080/api/v1/project/my-project/packages/releases?include_
 ### Upload an Artifact
 
 ```bash
+# Upload with tag only (version auto-detected from filename)
 curl -X POST http://localhost:8080/api/v1/project/my-project/releases/upload \
   -F "file=@./build/app-v1.0.0.tar.gz" \
-  -F "tag=v1.0.0"
+  -F "tag=latest"
+
+# Upload with explicit version and tag
+curl -X POST http://localhost:8080/api/v1/project/my-project/releases/upload \
+  -F "file=@./build/app-v1.0.0.tar.gz" \
+  -F "tag=latest" \
+  -F "version=1.0.0"
 ```
 
 Response:
@@ -242,7 +255,9 @@ Response:
   "size": 1048576,
   "project": "my-project",
   "package": "releases",
-  "tag": "v1.0.0",
+  "tag": "latest",
+  "version": "1.0.0",
+  "version_source": "explicit",
   "format_metadata": {
     "format": "tarball",
     "package_name": "app",
@@ -400,6 +415,38 @@ curl http://localhost:8080/api/v1/project/my-project/releases/tags/latest/histor
 
 Returns list of artifact changes for the tag (most recent first).
 
+### List Versions
+
+```bash
+# Basic listing
+curl http://localhost:8080/api/v1/project/my-project/releases/versions
+
+# With pagination and sorting
+curl "http://localhost:8080/api/v1/project/my-project/releases/versions?sort=version&order=desc"
+```
+
+Response includes tags pointing to each version's artifact:
+```json
+{
+  "items": [
+    {
+      "id": "uuid",
+      "package_id": "uuid",
+      "version": "1.0.0",
+      "version_source": "explicit",
+      "artifact_id": "a3f5d8e...",
+      "size": 1048576,
+      "content_type": "application/gzip",
+      "original_name": "app-v1.0.0.tar.gz",
+      "created_at": "2025-01-01T00:00:00Z",
+      "created_by": "user",
+      "tags": ["latest", "stable"]
+    }
+  ],
+  "pagination": {"page": 1, "limit": 20, "total": 1, "total_pages": 1}
+}
+```
+
 ### List Artifacts in Package
 
 ```bash
@@ -614,7 +661,8 @@ See `helm/orchard/values.yaml` for all configuration options.
 - **projects** - Top-level organizational containers
 - **packages** - Collections within projects
 - **artifacts** - Content-addressable artifacts (SHA256)
-- **tags** - Aliases pointing to artifacts
+- **tags** - Mutable aliases pointing to artifacts
+- **package_versions** - Immutable version records (set at upload time)
 - **tag_history** - Audit trail for tag changes
 - **uploads** - Upload event records
 - **consumers** - Dependency tracking

backend/app/database.py

@@ -151,6 +151,140 @@ def _run_migrations():
             END IF;
         END $$;
         """,
+        # Add package_versions indexes and triggers (007_package_versions.sql)
+        """
+        DO $$
+        BEGIN
+            -- Create indexes for package_versions if table exists
+            IF EXISTS (SELECT 1 FROM information_schema.tables WHERE table_name = 'package_versions') THEN
+                -- Indexes for common queries
+                IF NOT EXISTS (SELECT 1 FROM pg_indexes WHERE indexname = 'idx_package_versions_package_id') THEN
+                    CREATE INDEX idx_package_versions_package_id ON package_versions(package_id);
+                END IF;
+                IF NOT EXISTS (SELECT 1 FROM pg_indexes WHERE indexname = 'idx_package_versions_artifact_id') THEN
+                    CREATE INDEX idx_package_versions_artifact_id ON package_versions(artifact_id);
+                END IF;
+                IF NOT EXISTS (SELECT 1 FROM pg_indexes WHERE indexname = 'idx_package_versions_package_version') THEN
+                    CREATE INDEX idx_package_versions_package_version ON package_versions(package_id, version);
+                END IF;
+            END IF;
+        END $$;
+        """,
+        # Create ref_count trigger functions for tags (ensures triggers exist even if initial migration wasn't run)
+        """
+        CREATE OR REPLACE FUNCTION increment_artifact_ref_count()
+        RETURNS TRIGGER AS $$
+        BEGIN
+            UPDATE artifacts SET ref_count = ref_count + 1 WHERE id = NEW.artifact_id;
+            RETURN NEW;
+        END;
+        $$ LANGUAGE plpgsql;
+        """,
+        """
+        CREATE OR REPLACE FUNCTION decrement_artifact_ref_count()
+        RETURNS TRIGGER AS $$
+        BEGIN
+            UPDATE artifacts SET ref_count = ref_count - 1 WHERE id = OLD.artifact_id;
+            RETURN OLD;
+        END;
+        $$ LANGUAGE plpgsql;
+        """,
+        """
+        CREATE OR REPLACE FUNCTION update_artifact_ref_count()
+        RETURNS TRIGGER AS $$
+        BEGIN
+            IF OLD.artifact_id != NEW.artifact_id THEN
+                UPDATE artifacts SET ref_count = ref_count - 1 WHERE id = OLD.artifact_id;
+                UPDATE artifacts SET ref_count = ref_count + 1 WHERE id = NEW.artifact_id;
+            END IF;
+            RETURN NEW;
+        END;
+        $$ LANGUAGE plpgsql;
+        """,
+        # Create triggers for tags ref_count management
+        """
+        DO $$
+        BEGIN
+            -- Drop and recreate triggers to ensure they're current
+            DROP TRIGGER IF EXISTS tags_ref_count_insert_trigger ON tags;
+            CREATE TRIGGER tags_ref_count_insert_trigger
+                AFTER INSERT ON tags
+                FOR EACH ROW
+                EXECUTE FUNCTION increment_artifact_ref_count();
+
+            DROP TRIGGER IF EXISTS tags_ref_count_delete_trigger ON tags;
+            CREATE TRIGGER tags_ref_count_delete_trigger
+                AFTER DELETE ON tags
+                FOR EACH ROW
+                EXECUTE FUNCTION decrement_artifact_ref_count();
+
+            DROP TRIGGER IF EXISTS tags_ref_count_update_trigger ON tags;
+            CREATE TRIGGER tags_ref_count_update_trigger
+                AFTER UPDATE ON tags
+                FOR EACH ROW
+                WHEN (OLD.artifact_id IS DISTINCT FROM NEW.artifact_id)
+                EXECUTE FUNCTION update_artifact_ref_count();
+        END $$;
+        """,
+        # Create ref_count trigger functions for package_versions
+        """
+        CREATE OR REPLACE FUNCTION increment_version_ref_count()
+        RETURNS TRIGGER AS $$
+        BEGIN
+            UPDATE artifacts SET ref_count = ref_count + 1 WHERE id = NEW.artifact_id;
+            RETURN NEW;
+        END;
+        $$ LANGUAGE plpgsql;
+        """,
+        """
+        CREATE OR REPLACE FUNCTION decrement_version_ref_count()
+        RETURNS TRIGGER AS $$
+        BEGIN
+            UPDATE artifacts SET ref_count = ref_count - 1 WHERE id = OLD.artifact_id;
+            RETURN OLD;
+        END;
+        $$ LANGUAGE plpgsql;
+        """,
+        # Create triggers for package_versions ref_count
+        """
+        DO $$
+        BEGIN
+            IF EXISTS (SELECT 1 FROM information_schema.tables WHERE table_name = 'package_versions') THEN
+                -- Drop and recreate triggers to ensure they're current
+                DROP TRIGGER IF EXISTS package_versions_ref_count_insert ON package_versions;
+                CREATE TRIGGER package_versions_ref_count_insert
+                    AFTER INSERT ON package_versions
+                    FOR EACH ROW
+                    EXECUTE FUNCTION increment_version_ref_count();
+
+                DROP TRIGGER IF EXISTS package_versions_ref_count_delete ON package_versions;
+                CREATE TRIGGER package_versions_ref_count_delete
+                    AFTER DELETE ON package_versions
+                    FOR EACH ROW
+                    EXECUTE FUNCTION decrement_version_ref_count();
+            END IF;
+        END $$;
+        """,
+        # Migrate existing semver tags to package_versions
+        r"""
+        DO $$
+        BEGIN
+            IF EXISTS (SELECT 1 FROM information_schema.tables WHERE table_name = 'package_versions') THEN
+                -- Migrate tags that look like versions (v1.0.0, 1.2.3, 2.0.0-beta, etc.)
+                INSERT INTO package_versions (package_id, artifact_id, version, version_source, created_by, created_at)
+                SELECT
+                    t.package_id,
+                    t.artifact_id,
+                    CASE WHEN t.name LIKE 'v%' THEN substring(t.name from 2) ELSE t.name END,
+                    'migrated_from_tag',
+                    t.created_by,
+                    t.created_at
+                FROM tags t
+                WHERE t.name ~ '^v?[0-9]+\.[0-9]+(\.[0-9]+)?([-.][a-zA-Z0-9]+)?$'
+                ON CONFLICT (package_id, version) DO NOTHING;
+            END IF;
+        END $$;
+        """,
     ]
 
     with engine.connect() as conn:

backend/app/dependencies.py

@@ -0,0 +1,723 @@
+"""
+Dependency management module for artifact dependencies.
+
+Handles:
+- Parsing orchard.ensure files
+- Storing dependencies in the database
+- Querying dependencies and reverse dependencies
+- Dependency resolution with topological sorting
+- Circular dependency detection
+- Conflict detection
+"""
+
+import yaml
+from typing import List, Dict, Any, Optional, Set, Tuple
+from sqlalchemy.orm import Session
+from sqlalchemy import and_
+
+from .models import (
+    Project,
+    Package,
+    Artifact,
+    Tag,
+    ArtifactDependency,
+    PackageVersion,
+)
+from .schemas import (
+    EnsureFileContent,
+    EnsureFileDependency,
+    DependencyResponse,
+    ArtifactDependenciesResponse,
+    DependentInfo,
+    ReverseDependenciesResponse,
+    ResolvedArtifact,
+    DependencyResolutionResponse,
+    DependencyConflict,
+    PaginationMeta,
+)
+
+
+class DependencyError(Exception):
+    """Base exception for dependency errors."""
+    pass
+
+
+class CircularDependencyError(DependencyError):
+    """Raised when a circular dependency is detected."""
+    def __init__(self, cycle: List[str]):
+        self.cycle = cycle
+        super().__init__(f"Circular dependency detected: {' -> '.join(cycle)}")
+
+
+class DependencyConflictError(DependencyError):
+    """Raised when conflicting dependency versions are detected."""
+    def __init__(self, conflicts: List[DependencyConflict]):
+        self.conflicts = conflicts
+        super().__init__(f"Dependency conflicts detected: {len(conflicts)} conflict(s)")
+
+
+class DependencyNotFoundError(DependencyError):
+    """Raised when a dependency cannot be resolved."""
+    def __init__(self, project: str, package: str, constraint: str):
+        self.project = project
+        self.package = package
+        self.constraint = constraint
+        super().__init__(f"Dependency not found: {project}/{package}@{constraint}")
+
+
+class InvalidEnsureFileError(DependencyError):
+    """Raised when the ensure file is invalid."""
+    pass
+
+
+class DependencyDepthExceededError(DependencyError):
+    """Raised when dependency resolution exceeds max depth."""
+    def __init__(self, max_depth: int):
+        self.max_depth = max_depth
+        super().__init__(f"Dependency resolution exceeded maximum depth of {max_depth}")
+
+
+# Safety limits to prevent DoS attacks
+MAX_DEPENDENCY_DEPTH = 50  # Maximum levels of nested dependencies
+MAX_DEPENDENCIES_PER_ARTIFACT = 200  # Maximum direct dependencies per artifact
+
+
+def parse_ensure_file(content: bytes) -> EnsureFileContent:
+    """
+    Parse an orchard.ensure file.
+
+    Args:
+        content: Raw bytes of the ensure file
+
+    Returns:
+        Parsed EnsureFileContent
+
+    Raises:
+        InvalidEnsureFileError: If the file is invalid YAML or has wrong structure
+    """
+    try:
+        data = yaml.safe_load(content.decode('utf-8'))
+    except yaml.YAMLError as e:
+        raise InvalidEnsureFileError(f"Invalid YAML: {e}")
+    except UnicodeDecodeError as e:
+        raise InvalidEnsureFileError(f"Invalid encoding: {e}")
+
+    if data is None:
+        return EnsureFileContent(dependencies=[])
+
+    if not isinstance(data, dict):
+        raise InvalidEnsureFileError("Ensure file must be a YAML dictionary")
+
+    dependencies = []
+    deps_data = data.get('dependencies', [])
+
+    if not isinstance(deps_data, list):
+        raise InvalidEnsureFileError("'dependencies' must be a list")
+
+    # Safety limit: prevent DoS through excessive dependencies
+    if len(deps_data) > MAX_DEPENDENCIES_PER_ARTIFACT:
+        raise InvalidEnsureFileError(
+            f"Too many dependencies: {len(deps_data)} exceeds maximum of {MAX_DEPENDENCIES_PER_ARTIFACT}"
+        )
+
+    for i, dep in enumerate(deps_data):
+        if not isinstance(dep, dict):
+            raise InvalidEnsureFileError(f"Dependency {i} must be a dictionary")
+
+        project = dep.get('project')
+        package = dep.get('package')
+        version = dep.get('version')
+        tag = dep.get('tag')
+
+        if not project:
+            raise InvalidEnsureFileError(f"Dependency {i} missing 'project'")
+        if not package:
+            raise InvalidEnsureFileError(f"Dependency {i} missing 'package'")
+        if not version and not tag:
+            raise InvalidEnsureFileError(
+                f"Dependency {i} must have either 'version' or 'tag'"
+            )
+        if version and tag:
+            raise InvalidEnsureFileError(
+                f"Dependency {i} cannot have both 'version' and 'tag'"
+            )
+
+        dependencies.append(EnsureFileDependency(
+            project=project,
+            package=package,
+            version=version,
+            tag=tag,
+        ))
+
+    return EnsureFileContent(dependencies=dependencies)
+
+
+def validate_dependencies(
+    db: Session,
+    dependencies: List[EnsureFileDependency],
+) -> List[str]:
+    """
+    Validate that all dependency projects exist.
+
+    Args:
+        db: Database session
+        dependencies: List of dependencies to validate
+
+    Returns:
+        List of error messages (empty if all valid)
+    """
+    errors = []
+
+    for dep in dependencies:
+        project = db.query(Project).filter(Project.name == dep.project).first()
+        if not project:
+            errors.append(f"Project '{dep.project}' not found")
+
+    return errors
+
+
+def store_dependencies(
+    db: Session,
+    artifact_id: str,
+    dependencies: List[EnsureFileDependency],
+) -> List[ArtifactDependency]:
+    """
+    Store dependencies for an artifact.
+
+    Args:
+        db: Database session
+        artifact_id: The artifact ID that has these dependencies
+        dependencies: List of dependencies to store
+
+    Returns:
+        List of created ArtifactDependency objects
+    """
+    created = []
+
+    for dep in dependencies:
+        artifact_dep = ArtifactDependency(
+            artifact_id=artifact_id,
+            dependency_project=dep.project,
+            dependency_package=dep.package,
+            version_constraint=dep.version,
+            tag_constraint=dep.tag,
+        )
+        db.add(artifact_dep)
+        created.append(artifact_dep)
+
+    return created
+
+
+def get_artifact_dependencies(
+    db: Session,
+    artifact_id: str,
+) -> List[DependencyResponse]:
+    """
+    Get all dependencies for an artifact.
+
+    Args:
+        db: Database session
+        artifact_id: The artifact ID
+
+    Returns:
+        List of DependencyResponse objects
+    """
+    deps = db.query(ArtifactDependency).filter(
+        ArtifactDependency.artifact_id == artifact_id
+    ).all()
+
+    return [DependencyResponse.from_orm_model(dep) for dep in deps]
+
+
+def get_reverse_dependencies(
+    db: Session,
+    project_name: str,
+    package_name: str,
+    page: int = 1,
+    limit: int = 50,
+) -> ReverseDependenciesResponse:
+    """
+    Get all artifacts that depend on a given package.
+
+    Args:
+        db: Database session
+        project_name: Target project name
+        package_name: Target package name
+        page: Page number (1-indexed)
+        limit: Results per page
+
+    Returns:
+        ReverseDependenciesResponse with dependents and pagination
+    """
+    # Query dependencies that point to this project/package
+    query = db.query(ArtifactDependency).filter(
+        ArtifactDependency.dependency_project == project_name,
+        ArtifactDependency.dependency_package == package_name,
+    )
+
+    total = query.count()
+    offset = (page - 1) * limit
+    deps = query.offset(offset).limit(limit).all()
+
+    dependents = []
+    for dep in deps:
+        # Get artifact info to find the project/package/version
+        artifact = db.query(Artifact).filter(Artifact.id == dep.artifact_id).first()
+        if not artifact:
+            continue
+
+        # Find which package this artifact belongs to via tags or versions
+        tag = db.query(Tag).filter(Tag.artifact_id == dep.artifact_id).first()
+        if tag:
+            pkg = db.query(Package).filter(Package.id == tag.package_id).first()
+            if pkg:
+                proj = db.query(Project).filter(Project.id == pkg.project_id).first()
+                if proj:
+                    # Get version if available
+                    version_record = db.query(PackageVersion).filter(
+                        PackageVersion.artifact_id == dep.artifact_id,
+                        PackageVersion.package_id == pkg.id,
+                    ).first()
+
+                    dependents.append(DependentInfo(
+                        artifact_id=dep.artifact_id,
+                        project=proj.name,
+                        package=pkg.name,
+                        version=version_record.version if version_record else None,
+                        constraint_type="version" if dep.version_constraint else "tag",
+                        constraint_value=dep.version_constraint or dep.tag_constraint,
+                    ))
+
+    total_pages = (total + limit - 1) // limit
+
+    return ReverseDependenciesResponse(
+        project=project_name,
+        package=package_name,
+        dependents=dependents,
+        pagination=PaginationMeta(
+            page=page,
+            limit=limit,
+            total=total,
+            total_pages=total_pages,
+            has_more=page < total_pages,
+        ),
+    )
+
+
+def _resolve_dependency_to_artifact(
+    db: Session,
+    project_name: str,
+    package_name: str,
+    version: Optional[str],
+    tag: Optional[str],
+) -> Optional[Tuple[str, str, int]]:
+    """
+    Resolve a dependency constraint to an artifact ID.
+
+    Args:
+        db: Database session
+        project_name: Project name
+        package_name: Package name
+        version: Version constraint (exact)
+        tag: Tag constraint
+
+    Returns:
+        Tuple of (artifact_id, resolved_version_or_tag, size) or None if not found
+    """
+    # Get project and package
+    project = db.query(Project).filter(Project.name == project_name).first()
+    if not project:
+        return None
+
+    package = db.query(Package).filter(
+        Package.project_id == project.id,
+        Package.name == package_name,
+    ).first()
+    if not package:
+        return None
+
+    if version:
+        # Look up by version
+        pkg_version = db.query(PackageVersion).filter(
+            PackageVersion.package_id == package.id,
+            PackageVersion.version == version,
+        ).first()
+        if pkg_version:
+            artifact = db.query(Artifact).filter(
+                Artifact.id == pkg_version.artifact_id
+            ).first()
+            if artifact:
+                return (artifact.id, version, artifact.size)
+
+        # Also check if there's a tag with this exact name
+        tag_record = db.query(Tag).filter(
+            Tag.package_id == package.id,
+            Tag.name == version,
+        ).first()
+        if tag_record:
+            artifact = db.query(Artifact).filter(
+                Artifact.id == tag_record.artifact_id
+            ).first()
+            if artifact:
+                return (artifact.id, version, artifact.size)
+
+    if tag:
+        # Look up by tag
+        tag_record = db.query(Tag).filter(
+            Tag.package_id == package.id,
+            Tag.name == tag,
+        ).first()
+        if tag_record:
+            artifact = db.query(Artifact).filter(
+                Artifact.id == tag_record.artifact_id
+            ).first()
+            if artifact:
+                return (artifact.id, tag, artifact.size)
+
+    return None
+
+
+def _detect_package_cycle(
+    db: Session,
+    project_name: str,
+    package_name: str,
+    target_project: str,
+    target_package: str,
+    visiting: Set[str],
+    visited: Set[str],
+    path: List[str],
+) -> Optional[List[str]]:
+    """
+    Detect cycles at the package level using DFS.
+
+    Args:
+        db: Database session
+        project_name: Current project being visited
+        package_name: Current package being visited
+        target_project: The project we're checking for cycles back to
+        target_package: The package we're checking for cycles back to
+        visiting: Set of package keys currently in the recursion stack
+        visited: Set of fully processed package keys
+        path: Current path for cycle reporting
+
+    Returns:
+        Cycle path if detected, None otherwise
+    """
+    pkg_key = f"{project_name}/{package_name}"
+
+    # Check if we've reached the target package (cycle detected)
+    if project_name == target_project and package_name == target_package:
+        return path + [pkg_key]
+
+    if pkg_key in visiting:
+        # Unexpected internal cycle
+        return None
+
+    if pkg_key in visited:
+        return None
+
+    visiting.add(pkg_key)
+    path.append(pkg_key)
+
+    # Get the package and find any artifacts with dependencies
+    project = db.query(Project).filter(Project.name == project_name).first()
+    if project:
+        package = db.query(Package).filter(
+            Package.project_id == project.id,
+            Package.name == package_name,
+        ).first()
+        if package:
+            # Find all artifacts in this package via tags
+            tags = db.query(Tag).filter(Tag.package_id == package.id).all()
+            artifact_ids = {t.artifact_id for t in tags}
+
+            # Get dependencies from all artifacts in this package
+            for artifact_id in artifact_ids:
+                deps = db.query(ArtifactDependency).filter(
+                    ArtifactDependency.artifact_id == artifact_id
+                ).all()
+
+                for dep in deps:
+                    cycle = _detect_package_cycle(
+                        db,
+                        dep.dependency_project,
+                        dep.dependency_package,
+                        target_project,
+                        target_package,
+                        visiting,
+                        visited,
+                        path,
+                    )
+                    if cycle:
+                        return cycle
+
+    path.pop()
+    visiting.remove(pkg_key)
+    visited.add(pkg_key)
+
+    return None
+
+
+def check_circular_dependencies(
+    db: Session,
+    artifact_id: str,
+    new_dependencies: List[EnsureFileDependency],
+    project_name: Optional[str] = None,
+    package_name: Optional[str] = None,
+) -> Optional[List[str]]:
+    """
+    Check if adding the new dependencies would create a circular dependency.
+
+    Args:
+        db: Database session
+        artifact_id: The artifact that will have these dependencies
+        new_dependencies: Dependencies to be added
+        project_name: Project name (optional, will try to look up from tag if not provided)
+        package_name: Package name (optional, will try to look up from tag if not provided)
+
+    Returns:
+        Cycle path if detected, None otherwise
+    """
+    # First, get the package info for this artifact to build path labels
+    if project_name and package_name:
+        current_path = f"{project_name}/{package_name}"
+    else:
+        # Try to look up from tag
+        artifact = db.query(Artifact).filter(Artifact.id == artifact_id).first()
+        if not artifact:
+            return None
+
+        # Find package for this artifact
+        tag = db.query(Tag).filter(Tag.artifact_id == artifact_id).first()
+        if not tag:
+            return None
+
+        package = db.query(Package).filter(Package.id == tag.package_id).first()
+        if not package:
+            return None
+
+        project = db.query(Project).filter(Project.id == package.project_id).first()
+        if not project:
+            return None
+
+        current_path = f"{project.name}/{package.name}"
+
+    # Extract target project and package from current_path
+    if "/" in current_path:
+        target_project, target_package = current_path.split("/", 1)
+    else:
+        return None
+
+    # For each new dependency, check if it would create a cycle back to our package
+    for dep in new_dependencies:
+        # Check if this dependency (transitively) depends on us at the package level
+        visiting: Set[str] = set()
+        visited: Set[str] = set()
+        path: List[str] = [current_path]
+
+        # Check from the dependency's package
+        cycle = _detect_package_cycle(
+            db,
+            dep.project,
+            dep.package,
+            target_project,
+            target_package,
+            visiting,
+            visited,
+            path,
+        )
+        if cycle:
+            return cycle
+
+    return None
+
+
+def resolve_dependencies(
+    db: Session,
+    project_name: str,
+    package_name: str,
+    ref: str,
+    base_url: str,
+) -> DependencyResolutionResponse:
+    """
+    Resolve all dependencies for an artifact recursively.
+
+    Args:
+        db: Database session
+        project_name: Project name
+        package_name: Package name
+        ref: Tag or version reference
+        base_url: Base URL for download URLs
+
+    Returns:
+        DependencyResolutionResponse with all resolved artifacts
+
+    Raises:
+        DependencyNotFoundError: If a dependency cannot be resolved
+        CircularDependencyError: If circular dependencies are detected
+        DependencyConflictError: If conflicting versions are required
+    """
+    # Resolve the initial artifact
+    project = db.query(Project).filter(Project.name == project_name).first()
+    if not project:
+        raise DependencyNotFoundError(project_name, package_name, ref)
+
+    package = db.query(Package).filter(
+        Package.project_id == project.id,
+        Package.name == package_name,
+    ).first()
+    if not package:
+        raise DependencyNotFoundError(project_name, package_name, ref)
+
+    # Try to find artifact by tag or version
+    resolved = _resolve_dependency_to_artifact(
+        db, project_name, package_name, ref, ref
+    )
+    if not resolved:
+        raise DependencyNotFoundError(project_name, package_name, ref)
+
+    root_artifact_id, root_version, root_size = resolved
+
+    # Track resolved artifacts and their versions
+    resolved_artifacts: Dict[str, ResolvedArtifact] = {}
+    # Track version requirements for conflict detection
+    version_requirements: Dict[str, List[Dict[str, Any]]] = {}  # pkg_key -> [(version, required_by)]
+    # Track visiting/visited for cycle detection
+    visiting: Set[str] = set()
+    visited: Set[str] = set()
+    # Resolution order (topological)
+    resolution_order: List[str] = []
+
+    def _resolve_recursive(
+        artifact_id: str,
+        proj_name: str,
+        pkg_name: str,
+        version_or_tag: str,
+        size: int,
+        required_by: Optional[str],
+        depth: int = 0,
+    ):
+        """Recursively resolve dependencies with cycle/conflict detection."""
+        # Safety limit: prevent DoS through deeply nested dependencies
+        if depth > MAX_DEPENDENCY_DEPTH:
+            raise DependencyDepthExceededError(MAX_DEPENDENCY_DEPTH)
+
+        pkg_key = f"{proj_name}/{pkg_name}"
+
+        # Cycle detection (at artifact level)
+        if artifact_id in visiting:
+            # Build cycle path
+            raise CircularDependencyError([pkg_key, pkg_key])
+
+        # Conflict detection - check if we've seen this package before with a different version
+        if pkg_key in version_requirements:
+            existing_versions = {r["version"] for r in version_requirements[pkg_key]}
+            if version_or_tag not in existing_versions:
+                # Conflict detected - same package, different version
+                requirements = version_requirements[pkg_key] + [
+                    {"version": version_or_tag, "required_by": required_by}
+                ]
+                raise DependencyConflictError([
+                    DependencyConflict(
+                        project=proj_name,
+                        package=pkg_name,
+                        requirements=[
+                            {
+                                "version": r["version"],
+                                "required_by": [{"path": r["required_by"]}] if r["required_by"] else []
+                            }
+                            for r in requirements
+                        ],
+                    )
+                ])
+            # Same version already resolved - skip
+            if artifact_id in visited:
+                return
+
+        if artifact_id in visited:
+            return
+
+        visiting.add(artifact_id)
+
+        # Track version requirement
+        if pkg_key not in version_requirements:
+            version_requirements[pkg_key] = []
+        version_requirements[pkg_key].append({
+            "version": version_or_tag,
+            "required_by": required_by,
+        })
+
+        # Get dependencies
+        deps = db.query(ArtifactDependency).filter(
+            ArtifactDependency.artifact_id == artifact_id
+        ).all()
+
+        # Resolve each dependency first (depth-first)
+        for dep in deps:
+            resolved_dep = _resolve_dependency_to_artifact(
+                db,
+                dep.dependency_project,
+                dep.dependency_package,
+                dep.version_constraint,
+                dep.tag_constraint,
+            )
+
+            if not resolved_dep:
+                constraint = dep.version_constraint or dep.tag_constraint
+                raise DependencyNotFoundError(
+                    dep.dependency_project,
+                    dep.dependency_package,
+                    constraint,
+                )
+
+            dep_artifact_id, dep_version, dep_size = resolved_dep
+            _resolve_recursive(
+                dep_artifact_id,
+                dep.dependency_project,
+                dep.dependency_package,
+                dep_version,
+                dep_size,
+                pkg_key,
+                depth + 1,
+            )
+
+        visiting.remove(artifact_id)
+        visited.add(artifact_id)
+
+        # Add to resolution order (dependencies before dependents)
+        resolution_order.append(artifact_id)
+
+        # Store resolved artifact info
+        resolved_artifacts[artifact_id] = ResolvedArtifact(
+            artifact_id=artifact_id,
+            project=proj_name,
+            package=pkg_name,
+            version=version_or_tag,
+            size=size,
+            download_url=f"{base_url}/api/v1/project/{proj_name}/{pkg_name}/+/{version_or_tag}",
+        )
+
+    # Start resolution from root
+    _resolve_recursive(
+        root_artifact_id,
+        project_name,
+        package_name,
+        root_version,
+        root_size,
+        None,
+    )
+
+    # Build response in topological order
+    resolved_list = [resolved_artifacts[aid] for aid in resolution_order]
+    total_size = sum(r.size for r in resolved_list)
+
+    return DependencyResolutionResponse(
+        requested={
+            "project": project_name,
+            "package": package_name,
+            "ref": ref,
+        },
+        resolved=resolved_list,
+        total_size=total_size,
+        artifact_count=len(resolved_list),
+    )

backend/app/metadata.py

@@ -245,9 +245,10 @@ def extract_tarball_metadata(file: BinaryIO, filename: str) -> Dict[str, Any]:
             break
 
     # Try to split name and version
+    # Handle optional 'v' prefix on version (e.g., package-v1.0.0)
     patterns = [
-        r"^(.+)-(\d+\.\d+(?:\.\d+)?(?:[-._]\w+)?)$",  # name-version
-        r"^(.+)_(\d+\.\d+(?:\.\d+)?(?:[-._]\w+)?)$",   # name_version
+        r"^(.+)-v?(\d+\.\d+(?:\.\d+)?(?:[-_]\w+)?)$",  # name-version or name-vversion
+        r"^(.+)_v?(\d+\.\d+(?:\.\d+)?(?:[-_]\w+)?)$",  # name_version or name_vversion
     ]
 
     for pattern in patterns:

backend/app/models.py

@@ -72,6 +72,9 @@ class Package(Base):
     consumers = relationship(
         "Consumer", back_populates="package", cascade="all, delete-orphan"
     )
+    versions = relationship(
+        "PackageVersion", back_populates="package", cascade="all, delete-orphan"
+    )
 
     __table_args__ = (
         Index("idx_packages_project_id", "project_id"),
@@ -113,6 +116,10 @@ class Artifact(Base):
 
     tags = relationship("Tag", back_populates="artifact")
     uploads = relationship("Upload", back_populates="artifact")
+    versions = relationship("PackageVersion", back_populates="artifact")
+    dependencies = relationship(
+        "ArtifactDependency", back_populates="artifact", cascade="all, delete-orphan"
+    )
 
     @property
     def sha256(self) -> str:
@@ -197,6 +204,38 @@ class TagHistory(Base):
     )
 
 
+class PackageVersion(Base):
+    """Immutable version record for a package-artifact relationship.
+
+    Separates versions (immutable, set at upload) from tags (mutable labels).
+    Each artifact in a package can have at most one version.
+    """
+
+    __tablename__ = "package_versions"
+
+    id = Column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
+    package_id = Column(
+        UUID(as_uuid=True),
+        ForeignKey("packages.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    artifact_id = Column(String(64), ForeignKey("artifacts.id"), nullable=False)
+    version = Column(String(255), nullable=False)
+    version_source = Column(String(50))  # 'explicit', 'filename', 'metadata', 'migrated_from_tag'
+    created_at = Column(DateTime(timezone=True), default=datetime.utcnow)
+    created_by = Column(String(255), nullable=False)
+
+    package = relationship("Package", back_populates="versions")
+    artifact = relationship("Artifact", back_populates="versions")
+
+    __table_args__ = (
+        Index("idx_package_versions_package_id", "package_id"),
+        Index("idx_package_versions_artifact_id", "artifact_id"),
+        Index("idx_package_versions_package_version", "package_id", "version", unique=True),
+        Index("idx_package_versions_package_artifact", "package_id", "artifact_id", unique=True),
+    )
+
+
 class Upload(Base):
     __tablename__ = "uploads"
 
@@ -471,3 +510,54 @@ class PackageHistory(Base):
         Index("idx_package_history_changed_at", "changed_at"),
         Index("idx_package_history_package_changed_at", "package_id", "changed_at"),
     )
+
+
+class ArtifactDependency(Base):
+    """Dependency declared by an artifact on another package.
+
+    Each artifact can declare dependencies on other packages, specifying either
+    an exact version or a tag. This enables recursive dependency resolution.
+    """
+
+    __tablename__ = "artifact_dependencies"
+
+    id = Column(UUID(as_uuid=True), primary_key=True, default=uuid.uuid4)
+    artifact_id = Column(
+        String(64),
+        ForeignKey("artifacts.id", ondelete="CASCADE"),
+        nullable=False,
+    )
+    dependency_project = Column(String(255), nullable=False)
+    dependency_package = Column(String(255), nullable=False)
+    version_constraint = Column(String(255), nullable=True)
+    tag_constraint = Column(String(255), nullable=True)
+    created_at = Column(DateTime(timezone=True), default=datetime.utcnow)
+
+    # Relationship to the artifact that declares this dependency
+    artifact = relationship("Artifact", back_populates="dependencies")
+
+    __table_args__ = (
+        # Exactly one of version_constraint or tag_constraint must be set
+        CheckConstraint(
+            "(version_constraint IS NOT NULL AND tag_constraint IS NULL) OR "
+            "(version_constraint IS NULL AND tag_constraint IS NOT NULL)",
+            name="check_constraint_type",
+        ),
+        # Each artifact can only depend on a specific project/package once
+        Index(
+            "idx_artifact_dependencies_artifact_id",
+            "artifact_id",
+        ),
+        Index(
+            "idx_artifact_dependencies_target",
+            "dependency_project",
+            "dependency_package",
+        ),
+        Index(
+            "idx_artifact_dependencies_unique",
+            "artifact_id",
+            "dependency_project",
+            "dependency_package",
+            unique=True,
+        ),
+    )

backend/app/schemas.py

@@ -173,6 +173,7 @@ class TagResponse(BaseModel):
     artifact_id: str
     created_at: datetime
     created_by: str
+    version: Optional[str] = None  # Version of the artifact this tag points to
 
     class Config:
         from_attributes = True
@@ -187,6 +188,7 @@ class TagDetailResponse(BaseModel):
     artifact_id: str
     created_at: datetime
     created_by: str
+    version: Optional[str] = None  # Version of the artifact this tag points to
     # Artifact metadata
     artifact_size: int
     artifact_content_type: Optional[str]
@@ -383,6 +385,7 @@ class GlobalTagResponse(BaseModel):
     package_name: str
     artifact_size: Optional[int] = None
     artifact_content_type: Optional[str] = None
+    version: Optional[str] = None  # Version of the artifact this tag points to
 
     class Config:
         from_attributes = True
@@ -396,6 +399,8 @@ class UploadResponse(BaseModel):
     project: str
     package: str
     tag: Optional[str]
+    version: Optional[str] = None  # Version assigned to this artifact
+    version_source: Optional[str] = None  # How version was determined: 'explicit', 'filename', 'metadata'
     checksum_md5: Optional[str] = None
     checksum_sha1: Optional[str] = None
     s3_etag: Optional[str] = None
@@ -407,6 +412,9 @@ class UploadResponse(BaseModel):
     content_type: Optional[str] = None
     original_name: Optional[str] = None
     created_at: Optional[datetime] = None
+    # Upload metrics (Issue #43)
+    duration_ms: Optional[int] = None  # Upload duration in milliseconds
+    throughput_mbps: Optional[float] = None  # Upload throughput in MB/s
 
 
 # Resumable upload schemas
@@ -418,6 +426,7 @@ class ResumableUploadInitRequest(BaseModel):
     content_type: Optional[str] = None
     size: int
     tag: Optional[str] = None
+    version: Optional[str] = None  # Explicit version (auto-detected if not provided)
 
     @field_validator("expected_hash")
     @classmethod
@@ -472,6 +481,21 @@ class ResumableUploadStatusResponse(BaseModel):
     total_uploaded_bytes: int
 
 
+class UploadProgressResponse(BaseModel):
+    """Progress information for an in-flight upload"""
+
+    upload_id: str
+    status: str  # 'in_progress', 'completed', 'failed', 'not_found'
+    bytes_uploaded: int = 0
+    bytes_total: Optional[int] = None
+    percent_complete: Optional[float] = None
+    parts_uploaded: int = 0
+    parts_total: Optional[int] = None
+    started_at: Optional[datetime] = None
+    elapsed_seconds: Optional[float] = None
+    throughput_mbps: Optional[float] = None
+
+
 # Consumer schemas
 class ConsumerResponse(BaseModel):
     id: UUID
@@ -484,6 +508,35 @@ class ConsumerResponse(BaseModel):
         from_attributes = True
 
 
+# Package version schemas
+class PackageVersionResponse(BaseModel):
+    """Immutable version record for an artifact in a package"""
+
+    id: UUID
+    package_id: UUID
+    artifact_id: str
+    version: str
+    version_source: Optional[str] = None  # 'explicit', 'filename', 'metadata', 'migrated_from_tag'
+    created_at: datetime
+    created_by: str
+    # Enriched fields from joins
+    size: Optional[int] = None
+    content_type: Optional[str] = None
+    original_name: Optional[str] = None
+    tags: List[str] = []  # Tag names pointing to this artifact
+
+    class Config:
+        from_attributes = True
+
+
+class PackageVersionDetailResponse(PackageVersionResponse):
+    """Version with full artifact metadata"""
+
+    format_metadata: Optional[Dict[str, Any]] = None
+    checksum_md5: Optional[str] = None
+    checksum_sha1: Optional[str] = None
+
+
 # Global search schemas
 class SearchResultProject(BaseModel):
     """Project result for global search"""
@@ -863,3 +916,140 @@ class ProjectWithAccessResponse(ProjectResponse):
     """Project response with user's access level"""
     user_access_level: Optional[str] = None
 
+
+# Artifact Dependency schemas
+class DependencyCreate(BaseModel):
+    """Schema for creating a dependency"""
+    project: str
+    package: str
+    version: Optional[str] = None
+    tag: Optional[str] = None
+
+    @field_validator('version', 'tag')
+    @classmethod
+    def validate_constraint(cls, v, info):
+        return v
+
+    def model_post_init(self, __context):
+        """Validate that exactly one of version or tag is set"""
+        if self.version is None and self.tag is None:
+            raise ValueError("Either 'version' or 'tag' must be specified")
+        if self.version is not None and self.tag is not None:
+            raise ValueError("Cannot specify both 'version' and 'tag'")
+
+
+class DependencyResponse(BaseModel):
+    """Schema for dependency response"""
+    id: UUID
+    artifact_id: str
+    project: str
+    package: str
+    version: Optional[str] = None
+    tag: Optional[str] = None
+    created_at: datetime
+
+    class Config:
+        from_attributes = True
+
+    @classmethod
+    def from_orm_model(cls, dep) -> "DependencyResponse":
+        """Create from ORM model with field mapping"""
+        return cls(
+            id=dep.id,
+            artifact_id=dep.artifact_id,
+            project=dep.dependency_project,
+            package=dep.dependency_package,
+            version=dep.version_constraint,
+            tag=dep.tag_constraint,
+            created_at=dep.created_at,
+        )
+
+
+class ArtifactDependenciesResponse(BaseModel):
+    """Response containing all dependencies for an artifact"""
+    artifact_id: str
+    dependencies: List[DependencyResponse]
+
+
+class DependentInfo(BaseModel):
+    """Information about an artifact that depends on a package"""
+    artifact_id: str
+    project: str
+    package: str
+    version: Optional[str] = None
+    constraint_type: str  # 'version' or 'tag'
+    constraint_value: str
+
+
+class ReverseDependenciesResponse(BaseModel):
+    """Response containing packages that depend on a given package"""
+    project: str
+    package: str
+    dependents: List[DependentInfo]
+    pagination: PaginationMeta
+
+
+class EnsureFileDependency(BaseModel):
+    """Dependency entry from orchard.ensure file"""
+    project: str
+    package: str
+    version: Optional[str] = None
+    tag: Optional[str] = None
+
+    @field_validator('version', 'tag')
+    @classmethod
+    def validate_constraint(cls, v, info):
+        return v
+
+    def model_post_init(self, __context):
+        """Validate that exactly one of version or tag is set"""
+        if self.version is None and self.tag is None:
+            raise ValueError("Either 'version' or 'tag' must be specified")
+        if self.version is not None and self.tag is not None:
+            raise ValueError("Cannot specify both 'version' and 'tag'")
+
+
+class EnsureFileContent(BaseModel):
+    """Parsed content of orchard.ensure file"""
+    dependencies: List[EnsureFileDependency] = []
+
+
+class ResolvedArtifact(BaseModel):
+    """A resolved artifact in the dependency tree"""
+    artifact_id: str
+    project: str
+    package: str
+    version: Optional[str] = None
+    tag: Optional[str] = None
+    size: int
+    download_url: str
+
+
+class DependencyResolutionResponse(BaseModel):
+    """Response from dependency resolution endpoint"""
+    requested: Dict[str, str]  # project, package, ref
+    resolved: List[ResolvedArtifact]
+    total_size: int
+    artifact_count: int
+
+
+class DependencyConflict(BaseModel):
+    """Details about a dependency conflict"""
+    project: str
+    package: str
+    requirements: List[Dict[str, Any]]  # version/tag and required_by info
+
+
+class DependencyConflictError(BaseModel):
+    """Error response for dependency conflicts"""
+    error: str = "dependency_conflict"
+    message: str
+    conflicts: List[DependencyConflict]
+
+
+class CircularDependencyError(BaseModel):
+    """Error response for circular dependencies"""
+    error: str = "circular_dependency"
+    message: str
+    cycle: List[str]  # List of "project/package" strings showing the cycle
+

backend/app/seed.py

@@ -5,7 +5,7 @@ import hashlib
 import logging
 from sqlalchemy.orm import Session
 
-from .models import Project, Package, Artifact, Tag, Upload
+from .models import Project, Package, Artifact, Tag, Upload, PackageVersion, ArtifactDependency
 from .storage import get_storage
 
 logger = logging.getLogger(__name__)
@@ -74,7 +74,7 @@ TEST_PROJECTS = [
     },
 ]
 
-# Sample artifacts to create (content, tags)
+# Sample artifacts to create (content, tags, version)
 TEST_ARTIFACTS = [
     {
         "project": "frontend-libs",
@@ -83,6 +83,7 @@ TEST_ARTIFACTS = [
         "filename": "ui-components-1.0.0.js",
         "content_type": "application/javascript",
         "tags": ["v1.0.0", "latest"],
+        "version": "1.0.0",
     },
     {
         "project": "frontend-libs",
@@ -91,6 +92,7 @@ TEST_ARTIFACTS = [
         "filename": "ui-components-1.1.0.js",
         "content_type": "application/javascript",
         "tags": ["v1.1.0"],
+        "version": "1.1.0",
     },
     {
         "project": "frontend-libs",
@@ -99,6 +101,7 @@ TEST_ARTIFACTS = [
         "filename": "tokens.json",
         "content_type": "application/json",
         "tags": ["v1.0.0", "latest"],
+        "version": "1.0.0",
     },
     {
         "project": "backend-services",
@@ -107,6 +110,7 @@ TEST_ARTIFACTS = [
         "filename": "utils-2.0.0.py",
         "content_type": "text/x-python",
         "tags": ["v2.0.0", "stable", "latest"],
+        "version": "2.0.0",
     },
     {
         "project": "backend-services",
@@ -115,9 +119,21 @@ TEST_ARTIFACTS = [
         "filename": "auth-lib-1.0.0.go",
         "content_type": "text/x-go",
         "tags": ["v1.0.0", "latest"],
+        "version": "1.0.0",
     },
 ]
 
+# Dependencies to create (source artifact -> dependency)
+# Format: (source_project, source_package, source_version, dep_project, dep_package, version_constraint, tag_constraint)
+TEST_DEPENDENCIES = [
+    # ui-components v1.1.0 depends on design-tokens v1.0.0
+    ("frontend-libs", "ui-components", "1.1.0", "frontend-libs", "design-tokens", "1.0.0", None),
+    # auth-lib v1.0.0 depends on common-utils v2.0.0
+    ("backend-services", "auth-lib", "1.0.0", "backend-services", "common-utils", "2.0.0", None),
+    # auth-lib v1.0.0 also depends on design-tokens (stable tag)
+    ("backend-services", "auth-lib", "1.0.0", "frontend-libs", "design-tokens", None, "latest"),
+]
+
 
 def is_database_empty(db: Session) -> bool:
     """Check if the database has any projects."""
@@ -160,9 +176,10 @@ def seed_database(db: Session) -> None:
 
     logger.info(f"Created {len(project_map)} projects and {len(package_map)} packages")
 
-    # Create artifacts and tags
+    # Create artifacts, tags, and versions
     artifact_count = 0
     tag_count = 0
+    version_count = 0
 
     for artifact_data in TEST_ARTIFACTS:
         project = project_map[artifact_data["project"]]
@@ -184,6 +201,11 @@ def seed_database(db: Session) -> None:
             logger.warning(f"Failed to store artifact in S3: {e}")
             continue
 
+        # Calculate ref_count: tags + version (if present)
+        ref_count = len(artifact_data["tags"])
+        if artifact_data.get("version"):
+            ref_count += 1
+
         # Create artifact record
         artifact = Artifact(
             id=sha256_hash,
@@ -192,7 +214,7 @@ def seed_database(db: Session) -> None:
             original_name=artifact_data["filename"],
             created_by="seed-user",
             s3_key=s3_key,
-            ref_count=len(artifact_data["tags"]),
+            ref_count=ref_count,
         )
         db.add(artifact)
 
@@ -206,6 +228,18 @@ def seed_database(db: Session) -> None:
         db.add(upload)
         artifact_count += 1
 
+        # Create version record if specified
+        if artifact_data.get("version"):
+            version = PackageVersion(
+                package_id=package.id,
+                artifact_id=sha256_hash,
+                version=artifact_data["version"],
+                version_source="explicit",
+                created_by="seed-user",
+            )
+            db.add(version)
+            version_count += 1
+
         # Create tags
         for tag_name in artifact_data["tags"]:
             tag = Tag(
@@ -217,6 +251,40 @@ def seed_database(db: Session) -> None:
             db.add(tag)
             tag_count += 1
 
+    db.flush()
+
+    # Create dependencies
+    dependency_count = 0
+    for dep_data in TEST_DEPENDENCIES:
+        src_project, src_package, src_version, dep_project, dep_package, version_constraint, tag_constraint = dep_data
+
+        # Find the source artifact by looking up its version
+        src_pkg = package_map.get((src_project, src_package))
+        if not src_pkg:
+            logger.warning(f"Source package not found: {src_project}/{src_package}")
+            continue
+
+        # Find the artifact for this version
+        src_version_record = db.query(PackageVersion).filter(
+            PackageVersion.package_id == src_pkg.id,
+            PackageVersion.version == src_version,
+        ).first()
+
+        if not src_version_record:
+            logger.warning(f"Source version not found: {src_project}/{src_package}@{src_version}")
+            continue
+
+        # Create the dependency
+        dependency = ArtifactDependency(
+            artifact_id=src_version_record.artifact_id,
+            dependency_project=dep_project,
+            dependency_package=dep_package,
+            version_constraint=version_constraint,
+            tag_constraint=tag_constraint,
+        )
+        db.add(dependency)
+        dependency_count += 1
+
     db.commit()
-    logger.info(f"Created {artifact_count} artifacts and {tag_count} tags")
+    logger.info(f"Created {artifact_count} artifacts, {tag_count} tags, {version_count} versions, and {dependency_count} dependencies")
     logger.info("Database seeding complete")

backend/app/storage.py

@@ -242,15 +242,19 @@ class S3Storage:
             },
         )
 
-        self.client = boto3.client(
-            "s3",
-            endpoint_url=settings.s3_endpoint if settings.s3_endpoint else None,
-            region_name=settings.s3_region,
-            aws_access_key_id=settings.s3_access_key_id,
-            aws_secret_access_key=settings.s3_secret_access_key,
-            config=config,
-            verify=settings.s3_verify_ssl,  # SSL/TLS verification
-        )
+        # Build client kwargs - only include credentials if explicitly provided
+        # This allows IRSA/IAM role credentials to be used when no explicit creds are set
+        client_kwargs = {
+            "endpoint_url": settings.s3_endpoint if settings.s3_endpoint else None,
+            "region_name": settings.s3_region,
+            "config": config,
+            "verify": settings.s3_verify_ssl,
+        }
+        if settings.s3_access_key_id and settings.s3_secret_access_key:
+            client_kwargs["aws_access_key_id"] = settings.s3_access_key_id
+            client_kwargs["aws_secret_access_key"] = settings.s3_secret_access_key
+
+        self.client = boto3.client("s3", **client_kwargs)
         self.bucket = settings.s3_bucket
         # Store active multipart uploads for resumable support
         self._active_uploads: Dict[str, Dict[str, Any]] = {}
@@ -378,10 +382,16 @@ class S3Storage:
         """
         # First pass: compute all hashes by streaming through file
         try:
+            import time
             sha256_hasher = hashlib.sha256()
             md5_hasher = hashlib.md5()
             sha1_hasher = hashlib.sha1()
             size = 0
+            hash_start_time = time.time()
+            last_log_time = hash_start_time
+            log_interval_seconds = 5  # Log progress every 5 seconds
+
+            logger.info(f"Computing hashes for large file: expected_size={content_length}")
 
             # Read file in chunks to compute hashes
             while True:
@@ -393,6 +403,18 @@ class S3Storage:
                 sha1_hasher.update(chunk)
                 size += len(chunk)
 
+                # Log hash computation progress periodically
+                current_time = time.time()
+                if current_time - last_log_time >= log_interval_seconds:
+                    elapsed = current_time - hash_start_time
+                    percent = (size / content_length) * 100 if content_length > 0 else 0
+                    throughput = (size / (1024 * 1024)) / elapsed if elapsed > 0 else 0
+                    logger.info(
+                        f"Hash computation progress: bytes={size}/{content_length} ({percent:.1f}%) "
+                        f"throughput={throughput:.2f}MB/s"
+                    )
+                    last_log_time = current_time
+
                 # Enforce file size limit during streaming (protection against spoofing)
                 if size > settings.max_file_size:
                     raise FileSizeExceededError(
@@ -405,6 +427,14 @@ class S3Storage:
             sha256_hash = sha256_hasher.hexdigest()
             md5_hash = md5_hasher.hexdigest()
             sha1_hash = sha1_hasher.hexdigest()
+
+            # Log hash computation completion
+            hash_elapsed = time.time() - hash_start_time
+            hash_throughput = (size / (1024 * 1024)) / hash_elapsed if hash_elapsed > 0 else 0
+            logger.info(
+                f"Hash computation completed: hash={sha256_hash[:16]}... "
+                f"size={size} duration={hash_elapsed:.2f}s throughput={hash_throughput:.2f}MB/s"
+            )
         except (HashComputationError, FileSizeExceededError):
             raise
         except Exception as e:
@@ -458,8 +488,19 @@ class S3Storage:
         upload_id = mpu["UploadId"]
 
         try:
+            import time
             parts = []
             part_number = 1
+            bytes_uploaded = 0
+            upload_start_time = time.time()
+            last_log_time = upload_start_time
+            log_interval_seconds = 5  # Log progress every 5 seconds
+
+            total_parts = (content_length + MULTIPART_CHUNK_SIZE - 1) // MULTIPART_CHUNK_SIZE
+            logger.info(
+                f"Starting multipart upload: hash={sha256_hash[:16]}... "
+                f"size={content_length} parts={total_parts}"
+            )
 
             while True:
                 chunk = file.read(MULTIPART_CHUNK_SIZE)
@@ -479,8 +520,32 @@ class S3Storage:
                         "ETag": response["ETag"],
                     }
                 )
+                bytes_uploaded += len(chunk)
+
+                # Log progress periodically
+                current_time = time.time()
+                if current_time - last_log_time >= log_interval_seconds:
+                    elapsed = current_time - upload_start_time
+                    percent = (bytes_uploaded / content_length) * 100
+                    throughput = (bytes_uploaded / (1024 * 1024)) / elapsed if elapsed > 0 else 0
+                    logger.info(
+                        f"Upload progress: hash={sha256_hash[:16]}... "
+                        f"part={part_number}/{total_parts} "
+                        f"bytes={bytes_uploaded}/{content_length} ({percent:.1f}%) "
+                        f"throughput={throughput:.2f}MB/s"
+                    )
+                    last_log_time = current_time
+
                 part_number += 1
 
+            # Log completion
+            total_elapsed = time.time() - upload_start_time
+            final_throughput = (content_length / (1024 * 1024)) / total_elapsed if total_elapsed > 0 else 0
+            logger.info(
+                f"Multipart upload completed: hash={sha256_hash[:16]}... "
+                f"size={content_length} duration={total_elapsed:.2f}s throughput={final_throughput:.2f}MB/s"
+            )
+
             # Complete multipart upload
             complete_response = self.client.complete_multipart_upload(
                 Bucket=self.bucket,
@@ -502,12 +567,28 @@ class S3Storage:
 
         except Exception as e:
             # Abort multipart upload on failure
-            logger.error(f"Multipart upload failed: {e}")
-            self.client.abort_multipart_upload(
-                Bucket=self.bucket,
-                Key=s3_key,
-                UploadId=upload_id,
+            error_str = str(e).lower()
+            is_client_disconnect = (
+                isinstance(e, (ConnectionResetError, BrokenPipeError)) or
+                "connection" in error_str or "broken pipe" in error_str or "reset" in error_str
             )
+            if is_client_disconnect:
+                logger.warning(
+                    f"Multipart upload aborted (client disconnect): hash={sha256_hash[:16]}... "
+                    f"parts_uploaded={len(parts)} bytes_uploaded={bytes_uploaded}"
+                )
+            else:
+                logger.error(f"Multipart upload failed: hash={sha256_hash[:16]}... error={e}")
+
+            try:
+                self.client.abort_multipart_upload(
+                    Bucket=self.bucket,
+                    Key=s3_key,
+                    UploadId=upload_id,
+                )
+                logger.info(f"Multipart upload aborted and cleaned up: upload_id={upload_id[:16]}...")
+            except Exception as abort_error:
+                logger.error(f"Failed to abort multipart upload: {abort_error}")
             raise
 
     def initiate_resumable_upload(self, expected_hash: str) -> Dict[str, Any]:
@@ -529,12 +610,17 @@ class S3Storage:
         mpu = self.client.create_multipart_upload(Bucket=self.bucket, Key=s3_key)
         upload_id = mpu["UploadId"]
 
+        import time
         session = {
             "upload_id": upload_id,
             "s3_key": s3_key,
             "already_exists": False,
             "parts": [],
             "expected_hash": expected_hash,
+            "started_at": time.time(),
+            "bytes_uploaded": 0,
+            "expected_size": None,  # Set when init provides size
+            "status": "in_progress",
         }
         self._active_uploads[upload_id] = session
         return session
@@ -561,10 +647,57 @@ class S3Storage:
         part_info = {
             "PartNumber": part_number,
             "ETag": response["ETag"],
+            "size": len(data),
         }
         session["parts"].append(part_info)
+        session["bytes_uploaded"] = session.get("bytes_uploaded", 0) + len(data)
         return part_info
 
+    def get_upload_progress(self, upload_id: str) -> Optional[Dict[str, Any]]:
+        """
+        Get progress information for a resumable upload.
+        Returns None if upload not found.
+        """
+        import time
+        session = self._active_uploads.get(upload_id)
+        if not session:
+            return None
+
+        bytes_uploaded = session.get("bytes_uploaded", 0)
+        expected_size = session.get("expected_size")
+        started_at = session.get("started_at")
+
+        progress = {
+            "upload_id": upload_id,
+            "status": session.get("status", "in_progress"),
+            "bytes_uploaded": bytes_uploaded,
+            "bytes_total": expected_size,
+            "parts_uploaded": len(session.get("parts", [])),
+            "parts_total": None,
+            "started_at": started_at,
+            "elapsed_seconds": None,
+            "percent_complete": None,
+            "throughput_mbps": None,
+        }
+
+        if expected_size and expected_size > 0:
+            progress["percent_complete"] = round((bytes_uploaded / expected_size) * 100, 2)
+            progress["parts_total"] = (expected_size + MULTIPART_CHUNK_SIZE - 1) // MULTIPART_CHUNK_SIZE
+
+        if started_at:
+            elapsed = time.time() - started_at
+            progress["elapsed_seconds"] = round(elapsed, 2)
+            if elapsed > 0 and bytes_uploaded > 0:
+                progress["throughput_mbps"] = round((bytes_uploaded / (1024 * 1024)) / elapsed, 2)
+
+        return progress
+
+    def set_upload_expected_size(self, upload_id: str, size: int):
+        """Set the expected size for an upload (for progress tracking)."""
+        session = self._active_uploads.get(upload_id)
+        if session:
+            session["expected_size"] = size
+
     def complete_resumable_upload(self, upload_id: str) -> Tuple[str, str]:
         """
         Complete a resumable upload.
@@ -702,6 +835,36 @@ class S3Storage:
         except ClientError:
             return False
 
+    def delete_all(self) -> int:
+        """
+        Delete all objects in the bucket.
+
+        Returns:
+            Number of objects deleted
+        """
+        deleted_count = 0
+        try:
+            paginator = self.client.get_paginator("list_objects_v2")
+            for page in paginator.paginate(Bucket=self.bucket):
+                objects = page.get("Contents", [])
+                if not objects:
+                    continue
+
+                # Delete objects in batches of 1000 (S3 limit)
+                delete_keys = [{"Key": obj["Key"]} for obj in objects]
+                if delete_keys:
+                    self.client.delete_objects(
+                        Bucket=self.bucket, Delete={"Objects": delete_keys}
+                    )
+                    deleted_count += len(delete_keys)
+                    logger.info(f"Deleted {len(delete_keys)} objects from S3")
+
+            logger.info(f"Total objects deleted from S3: {deleted_count}")
+            return deleted_count
+        except ClientError as e:
+            logger.error(f"Failed to delete all S3 objects: {e}")
+            raise
+
     def generate_presigned_url(
         self,
         s3_key: str,

backend/pytest.ini

@@ -12,6 +12,8 @@ markers =
     unit: Unit tests (no external dependencies)
     integration: Integration tests (require database/storage)
     slow: Slow tests (skip with -m "not slow")
+    large: Large file tests (100MB+, skip with -m "not large")
+    concurrent: Concurrent operation tests
 
 # Coverage configuration
 [coverage:run]

backend/tests/conftest.py

@@ -9,6 +9,37 @@ This module provides:
 
 import os
 import pytest
+
+
+# =============================================================================
+# Pytest Markers
+# =============================================================================
+
+
+def pytest_configure(config):
+    """Register custom pytest markers."""
+    config.addinivalue_line(
+        "markers",
+        "auth_intensive: marks tests that make many login requests (excluded from CI integration tests due to rate limiting)",
+    )
+    config.addinivalue_line(
+        "markers",
+        "integration: marks tests as integration tests",
+    )
+    config.addinivalue_line(
+        "markers",
+        "large: marks tests that handle large files (slow)",
+    )
+    config.addinivalue_line(
+        "markers",
+        "slow: marks tests as slow running",
+    )
+    config.addinivalue_line(
+        "markers",
+        "requires_direct_s3: marks tests that require direct S3/MinIO access (skipped in CI where S3 is not directly accessible)",
+    )
+
+
 import io
 from typing import Generator
 from unittest.mock import MagicMock
@@ -32,6 +63,8 @@ from tests.factories import (
     compute_md5,
     compute_sha1,
     upload_test_file,
+    generate_content,
+    generate_content_with_hash,
     TEST_CONTENT_HELLO,
     TEST_HASH_HELLO,
     TEST_MD5_HELLO,
@@ -179,29 +212,64 @@ def test_app():
 # =============================================================================
 
 
-@pytest.fixture
+@pytest.fixture(scope="session")
 def integration_client():
     """
     Create an authenticated test client for integration tests.
 
-    Uses the real database and MinIO from docker-compose.local.yml.
-    Authenticates as admin for write operations.
+    Uses the real database and MinIO from docker-compose.local.yml or deployed environment.
+    Authenticates as admin for write operations. Session-scoped to reuse login across tests.
+
+    Environment variables:
+        ORCHARD_TEST_URL: Base URL of the Orchard server (default: http://localhost:8080)
+        ORCHARD_TEST_USERNAME: Admin username for authentication (default: admin)
+        ORCHARD_TEST_PASSWORD: Admin password for authentication (default: changeme123)
     """
-    from httpx import Client
+    import httpx
 
-    # Connect to the running orchard-server container
+    # Connect to the running orchard-server container or deployed environment
     base_url = os.environ.get("ORCHARD_TEST_URL", "http://localhost:8080")
+    username = os.environ.get("ORCHARD_TEST_USERNAME", "admin")
+    password = os.environ.get("ORCHARD_TEST_PASSWORD", "changeme123")
 
-    with Client(base_url=base_url, timeout=30.0) as client:
+    with httpx.Client(base_url=base_url, timeout=30.0) as client:
         # Login as admin to enable write operations
         login_response = client.post(
             "/api/v1/auth/login",
-            json={"username": "admin", "password": "changeme123"},
+            json={"username": username, "password": password},
         )
-        # If login fails, tests will fail - that's expected if auth is broken
         if login_response.status_code != 200:
-            # Try to continue without auth for backward compatibility
-            pass
+            pytest.fail(
+                f"Authentication failed against {base_url}: {login_response.status_code} - {login_response.text}. "
+                f"Set ORCHARD_TEST_USERNAME and ORCHARD_TEST_PASSWORD environment variables if using non-default credentials."
+            )
+
+        # Verify cookie was set
+        if not client.cookies:
+            pytest.fail(
+                f"Login succeeded but no session cookie was set. Response headers: {login_response.headers}"
+            )
+
+        yield client
+
+
+@pytest.fixture
+def auth_client():
+    """
+    Create a function-scoped test client for authentication tests.
+
+    Unlike integration_client (session-scoped), this creates a fresh client
+    for each test. Use this for tests that manipulate authentication state
+    (login, logout, cookie clearing) to avoid polluting other tests.
+
+    Environment variables:
+        ORCHARD_TEST_URL: Base URL of the Orchard server (default: http://localhost:8080)
+    """
+    import httpx
+
+    base_url = os.environ.get("ORCHARD_TEST_URL", "http://localhost:8080")
+
+    with httpx.Client(base_url=base_url, timeout=30.0) as client:
         yield client
 
 
@@ -271,3 +339,41 @@ def test_content():
     content = f"test-content-{uuid.uuid4().hex}".encode()
     sha256 = compute_sha256(content)
     return (content, sha256)
+
+
+@pytest.fixture
+def sized_content():
+    """
+    Factory fixture for generating content of specific sizes.
+
+    Usage:
+        def test_example(sized_content):
+            content, hash = sized_content(1024)  # 1KB
+            content, hash = sized_content(1024 * 1024)  # 1MB
+    """
+    def _generate(size: int, seed: int = None):
+        return generate_content_with_hash(size, seed)
+    return _generate
+
+
+# =============================================================================
+# Size Constants for Tests
+# =============================================================================
+
+# Common file sizes for boundary testing
+SIZE_1B = 1
+SIZE_1KB = 1024
+SIZE_10KB = 10 * 1024
+SIZE_100KB = 100 * 1024
+SIZE_1MB = 1024 * 1024
+SIZE_5MB = 5 * 1024 * 1024
+SIZE_10MB = 10 * 1024 * 1024
+SIZE_50MB = 50 * 1024 * 1024
+SIZE_100MB = 100 * 1024 * 1024
+SIZE_250MB = 250 * 1024 * 1024
+SIZE_500MB = 500 * 1024 * 1024
+SIZE_1GB = 1024 * 1024 * 1024
+
+# Chunk size boundaries (based on typical S3 multipart chunk sizes)
+CHUNK_SIZE = 64 * 1024  # 64KB typical chunk
+MULTIPART_THRESHOLD = 100 * 1024 * 1024  # 100MB multipart threshold

backend/tests/factories.py

@@ -97,6 +97,7 @@ def upload_test_file(
     content: bytes,
     filename: str = "test.bin",
     tag: Optional[str] = None,
+    version: Optional[str] = None,
 ) -> dict:
     """
     Helper function to upload a test file via the API.
@@ -108,6 +109,7 @@ def upload_test_file(
         content: File content as bytes
         filename: Original filename
         tag: Optional tag to assign
+        version: Optional version to assign
 
     Returns:
         The upload response as a dict
@@ -116,6 +118,8 @@ def upload_test_file(
     data = {}
     if tag:
         data["tag"] = tag
+    if version:
+        data["version"] = version
 
     response = client.post(
         f"/api/v1/project/{project}/{package}/upload",
@@ -126,6 +130,41 @@ def upload_test_file(
     return response.json()
 
 
+def generate_content(size: int, seed: Optional[int] = None) -> bytes:
+    """
+    Generate deterministic or random content of a specified size.
+
+    Args:
+        size: Size of content in bytes
+        seed: Optional seed for reproducible content (None for random)
+
+    Returns:
+        Bytes of the specified size
+    """
+    if size == 0:
+        return b""
+    if seed is not None:
+        import random
+        rng = random.Random(seed)
+        return bytes(rng.randint(0, 255) for _ in range(size))
+    return os.urandom(size)
+
+
+def generate_content_with_hash(size: int, seed: Optional[int] = None) -> tuple[bytes, str]:
+    """
+    Generate content of specified size and compute its SHA256 hash.
+
+    Args:
+        size: Size of content in bytes
+        seed: Optional seed for reproducible content
+
+    Returns:
+        Tuple of (content_bytes, sha256_hash)
+    """
+    content = generate_content(size, seed)
+    return content, compute_sha256(content)
+
+
 # =============================================================================
 # Project/Package Factories
 # =============================================================================

backend/tests/integration/test_auth_api.py

@@ -1,16 +1,25 @@
-"""Integration tests for authentication API endpoints."""
+"""Integration tests for authentication API endpoints.
+
+Note: These tests are marked as auth_intensive because they make many login
+requests. Dev/stage deployments have relaxed rate limits (1000/minute) to
+allow these tests to run. Production uses strict rate limits (5/minute).
+"""
 
 import pytest
 from uuid import uuid4
 
 
+# Mark all tests in this module as auth_intensive (informational, not excluded from CI)
+pytestmark = pytest.mark.auth_intensive
+
+
 class TestAuthLogin:
     """Tests for login endpoint."""
 
     @pytest.mark.integration
-    def test_login_success(self, integration_client):
+    def test_login_success(self, auth_client):
         """Test successful login with default admin credentials."""
-        response = integration_client.post(
+        response = auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
@@ -21,9 +30,9 @@ class TestAuthLogin:
         assert "orchard_session" in response.cookies
 
     @pytest.mark.integration
-    def test_login_invalid_password(self, integration_client):
+    def test_login_invalid_password(self, auth_client):
         """Test login with wrong password."""
-        response = integration_client.post(
+        response = auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "wrongpassword"},
         )
@@ -31,9 +40,9 @@ class TestAuthLogin:
         assert "Invalid username or password" in response.json()["detail"]
 
     @pytest.mark.integration
-    def test_login_nonexistent_user(self, integration_client):
+    def test_login_nonexistent_user(self, auth_client):
         """Test login with non-existent user."""
-        response = integration_client.post(
+        response = auth_client.post(
             "/api/v1/auth/login",
             json={"username": "nonexistent", "password": "password"},
         )
@@ -44,24 +53,24 @@ class TestAuthLogout:
     """Tests for logout endpoint."""
 
     @pytest.mark.integration
-    def test_logout_success(self, integration_client):
+    def test_logout_success(self, auth_client):
         """Test successful logout."""
         # First login
-        login_response = integration_client.post(
+        login_response = auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
         assert login_response.status_code == 200
 
         # Then logout
-        logout_response = integration_client.post("/api/v1/auth/logout")
+        logout_response = auth_client.post("/api/v1/auth/logout")
         assert logout_response.status_code == 200
         assert "Logged out successfully" in logout_response.json()["message"]
 
     @pytest.mark.integration
-    def test_logout_without_session(self, integration_client):
+    def test_logout_without_session(self, auth_client):
         """Test logout without being logged in."""
-        response = integration_client.post("/api/v1/auth/logout")
+        response = auth_client.post("/api/v1/auth/logout")
         # Should succeed even without session
         assert response.status_code == 200
 
@@ -70,15 +79,15 @@ class TestAuthMe:
     """Tests for get current user endpoint."""
 
     @pytest.mark.integration
-    def test_get_me_authenticated(self, integration_client):
+    def test_get_me_authenticated(self, auth_client):
         """Test getting current user when authenticated."""
         # Login first
-        integration_client.post(
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
 
-        response = integration_client.get("/api/v1/auth/me")
+        response = auth_client.get("/api/v1/auth/me")
         assert response.status_code == 200
         data = response.json()
         assert data["username"] == "admin"
@@ -87,67 +96,88 @@ class TestAuthMe:
         assert "created_at" in data
 
     @pytest.mark.integration
-    def test_get_me_unauthenticated(self, integration_client):
+    def test_get_me_unauthenticated(self, auth_client):
         """Test getting current user without authentication."""
         # Clear any existing cookies
-        integration_client.cookies.clear()
+        auth_client.cookies.clear()
 
-        response = integration_client.get("/api/v1/auth/me")
+        response = auth_client.get("/api/v1/auth/me")
         assert response.status_code == 401
         assert "Not authenticated" in response.json()["detail"]
 
 
 class TestAuthChangePassword:
-    """Tests for change password endpoint."""
+    """Tests for change password endpoint.
+
+    Note: These tests use dedicated test users instead of admin to avoid
+    invalidating the integration_client session (which uses admin).
+    """
 
     @pytest.mark.integration
-    def test_change_password_success(self, integration_client):
+    def test_change_password_success(self, auth_client):
         """Test successful password change."""
-        # Login first
-        integration_client.post(
+        # Login as admin to create a test user
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
+        test_username = f"pwchange_{uuid4().hex[:8]}"
+        auth_client.post(
+            "/api/v1/admin/users",
+            json={"username": test_username, "password": "oldpassword123"},
+        )
+
+        # Login as test user
+        auth_client.cookies.clear()
+        auth_client.post(
+            "/api/v1/auth/login",
+            json={"username": test_username, "password": "oldpassword123"},
+        )
 
         # Change password
-        response = integration_client.post(
+        response = auth_client.post(
             "/api/v1/auth/change-password",
-            json={"current_password": "changeme123", "new_password": "newpassword123"},
+            json={"current_password": "oldpassword123", "new_password": "newpassword123"},
         )
         assert response.status_code == 200
 
         # Verify old password no longer works
-        integration_client.cookies.clear()
-        response = integration_client.post(
+        auth_client.cookies.clear()
+        response = auth_client.post(
             "/api/v1/auth/login",
-            json={"username": "admin", "password": "changeme123"},
+            json={"username": test_username, "password": "oldpassword123"},
         )
         assert response.status_code == 401
 
         # Verify new password works
-        response = integration_client.post(
+        response = auth_client.post(
             "/api/v1/auth/login",
-            json={"username": "admin", "password": "newpassword123"},
+            json={"username": test_username, "password": "newpassword123"},
         )
         assert response.status_code == 200
 
-        # Reset password back to original for other tests
-        reset_response = integration_client.post(
-            "/api/v1/auth/change-password",
-            json={"current_password": "newpassword123", "new_password": "changeme123"},
-        )
-        assert reset_response.status_code == 200, "Failed to reset admin password back to default"
-
     @pytest.mark.integration
-    def test_change_password_wrong_current(self, integration_client):
+    def test_change_password_wrong_current(self, auth_client):
         """Test password change with wrong current password."""
-        # Login first
-        integration_client.post(
+        # Login as admin to create a test user
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
+        test_username = f"pwwrong_{uuid4().hex[:8]}"
+        auth_client.post(
+            "/api/v1/admin/users",
+            json={"username": test_username, "password": "password123"},
+        )
 
-        response = integration_client.post(
+        # Login as test user
+        auth_client.cookies.clear()
+        auth_client.post(
+            "/api/v1/auth/login",
+            json={"username": test_username, "password": "password123"},
+        )
+
+        response = auth_client.post(
             "/api/v1/auth/change-password",
             json={"current_password": "wrongpassword", "new_password": "newpassword"},
         )
@@ -159,16 +189,16 @@ class TestAPIKeys:
     """Tests for API key management endpoints."""
 
     @pytest.mark.integration
-    def test_create_and_list_api_key(self, integration_client):
+    def test_create_and_list_api_key(self, auth_client):
         """Test creating and listing API keys."""
         # Login first
-        integration_client.post(
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
 
         # Create API key
-        create_response = integration_client.post(
+        create_response = auth_client.post(
             "/api/v1/auth/keys",
             json={"name": "test-key", "description": "Test API key"},
         )
@@ -182,23 +212,23 @@ class TestAPIKeys:
         api_key = data["key"]
 
         # List API keys
-        list_response = integration_client.get("/api/v1/auth/keys")
+        list_response = auth_client.get("/api/v1/auth/keys")
         assert list_response.status_code == 200
         keys = list_response.json()
         assert any(k["id"] == key_id for k in keys)
 
         # Clean up - delete the key
-        integration_client.delete(f"/api/v1/auth/keys/{key_id}")
+        auth_client.delete(f"/api/v1/auth/keys/{key_id}")
 
     @pytest.mark.integration
-    def test_use_api_key_for_auth(self, integration_client):
+    def test_use_api_key_for_auth(self, auth_client):
         """Test using API key for authentication."""
         # Login and create API key
-        integration_client.post(
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
-        create_response = integration_client.post(
+        create_response = auth_client.post(
             "/api/v1/auth/keys",
             json={"name": "auth-test-key"},
         )
@@ -206,8 +236,8 @@ class TestAPIKeys:
         key_id = create_response.json()["id"]
 
         # Clear cookies and use API key
-        integration_client.cookies.clear()
-        response = integration_client.get(
+        auth_client.cookies.clear()
+        response = auth_client.get(
             "/api/v1/auth/me",
             headers={"Authorization": f"Bearer {api_key}"},
         )
@@ -215,21 +245,21 @@ class TestAPIKeys:
         assert response.json()["username"] == "admin"
 
         # Clean up
-        integration_client.post(
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
-        integration_client.delete(f"/api/v1/auth/keys/{key_id}")
+        auth_client.delete(f"/api/v1/auth/keys/{key_id}")
 
     @pytest.mark.integration
-    def test_delete_api_key(self, integration_client):
+    def test_delete_api_key(self, auth_client):
         """Test revoking an API key."""
         # Login and create API key
-        integration_client.post(
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
-        create_response = integration_client.post(
+        create_response = auth_client.post(
             "/api/v1/auth/keys",
             json={"name": "delete-test-key"},
         )
@@ -237,12 +267,12 @@ class TestAPIKeys:
         api_key = create_response.json()["key"]
 
         # Delete the key
-        delete_response = integration_client.delete(f"/api/v1/auth/keys/{key_id}")
+        delete_response = auth_client.delete(f"/api/v1/auth/keys/{key_id}")
         assert delete_response.status_code == 200
 
         # Verify key no longer works
-        integration_client.cookies.clear()
-        response = integration_client.get(
+        auth_client.cookies.clear()
+        response = auth_client.get(
             "/api/v1/auth/me",
             headers={"Authorization": f"Bearer {api_key}"},
         )
@@ -253,32 +283,32 @@ class TestAdminUserManagement:
     """Tests for admin user management endpoints."""
 
     @pytest.mark.integration
-    def test_list_users(self, integration_client):
+    def test_list_users(self, auth_client):
         """Test listing users as admin."""
         # Login as admin
-        integration_client.post(
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
 
-        response = integration_client.get("/api/v1/admin/users")
+        response = auth_client.get("/api/v1/admin/users")
         assert response.status_code == 200
         users = response.json()
         assert len(users) >= 1
         assert any(u["username"] == "admin" for u in users)
 
     @pytest.mark.integration
-    def test_create_user(self, integration_client):
+    def test_create_user(self, auth_client):
         """Test creating a new user as admin."""
         # Login as admin
-        integration_client.post(
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
 
         # Create new user
         test_username = f"testuser_{uuid4().hex[:8]}"
-        response = integration_client.post(
+        response = auth_client.post(
             "/api/v1/admin/users",
             json={
                 "username": test_username,
@@ -293,31 +323,31 @@ class TestAdminUserManagement:
         assert data["is_admin"] is False
 
         # Verify new user can login
-        integration_client.cookies.clear()
-        login_response = integration_client.post(
+        auth_client.cookies.clear()
+        login_response = auth_client.post(
             "/api/v1/auth/login",
             json={"username": test_username, "password": "testpassword"},
         )
         assert login_response.status_code == 200
 
     @pytest.mark.integration
-    def test_update_user(self, integration_client):
+    def test_update_user(self, auth_client):
         """Test updating a user as admin."""
         # Login as admin
-        integration_client.post(
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
 
         # Create a test user
         test_username = f"updateuser_{uuid4().hex[:8]}"
-        integration_client.post(
+        auth_client.post(
             "/api/v1/admin/users",
             json={"username": test_username, "password": "password"},
         )
 
         # Update the user
-        response = integration_client.put(
+        response = auth_client.put(
             f"/api/v1/admin/users/{test_username}",
             json={"email": "updated@example.com", "is_admin": True},
         )
@@ -327,59 +357,59 @@ class TestAdminUserManagement:
         assert data["is_admin"] is True
 
     @pytest.mark.integration
-    def test_reset_user_password(self, integration_client):
+    def test_reset_user_password(self, auth_client):
         """Test resetting a user's password as admin."""
         # Login as admin
-        integration_client.post(
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
 
         # Create a test user
         test_username = f"resetuser_{uuid4().hex[:8]}"
-        integration_client.post(
+        auth_client.post(
             "/api/v1/admin/users",
             json={"username": test_username, "password": "oldpassword"},
         )
 
         # Reset password
-        response = integration_client.post(
+        response = auth_client.post(
             f"/api/v1/admin/users/{test_username}/reset-password",
             json={"new_password": "newpassword"},
         )
         assert response.status_code == 200
 
         # Verify new password works
-        integration_client.cookies.clear()
-        login_response = integration_client.post(
+        auth_client.cookies.clear()
+        login_response = auth_client.post(
             "/api/v1/auth/login",
             json={"username": test_username, "password": "newpassword"},
         )
         assert login_response.status_code == 200
 
     @pytest.mark.integration
-    def test_non_admin_cannot_access_admin_endpoints(self, integration_client):
+    def test_non_admin_cannot_access_admin_endpoints(self, auth_client):
         """Test that non-admin users cannot access admin endpoints."""
         # Login as admin and create non-admin user
-        integration_client.post(
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
         test_username = f"nonadmin_{uuid4().hex[:8]}"
-        integration_client.post(
+        auth_client.post(
             "/api/v1/admin/users",
             json={"username": test_username, "password": "password", "is_admin": False},
         )
 
         # Login as non-admin
-        integration_client.cookies.clear()
-        integration_client.post(
+        auth_client.cookies.clear()
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": test_username, "password": "password"},
         )
 
         # Try to access admin endpoints
-        response = integration_client.get("/api/v1/admin/users")
+        response = auth_client.get("/api/v1/admin/users")
         assert response.status_code == 403
         assert "Admin privileges required" in response.json()["detail"]
 
@@ -388,28 +418,28 @@ class TestSecurityEdgeCases:
     """Tests for security edge cases and validation."""
 
     @pytest.mark.integration
-    def test_login_inactive_user(self, integration_client):
+    def test_login_inactive_user(self, auth_client):
         """Test that inactive users cannot login."""
         # Login as admin and create a user
-        integration_client.post(
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
         test_username = f"inactive_{uuid4().hex[:8]}"
-        integration_client.post(
+        auth_client.post(
             "/api/v1/admin/users",
             json={"username": test_username, "password": "password123"},
         )
 
         # Deactivate the user
-        integration_client.put(
+        auth_client.put(
             f"/api/v1/admin/users/{test_username}",
             json={"is_active": False},
         )
 
         # Try to login as inactive user
-        integration_client.cookies.clear()
-        response = integration_client.post(
+        auth_client.cookies.clear()
+        response = auth_client.post(
             "/api/v1/auth/login",
             json={"username": test_username, "password": "password123"},
         )
@@ -417,14 +447,14 @@ class TestSecurityEdgeCases:
         assert "Invalid username or password" in response.json()["detail"]
 
     @pytest.mark.integration
-    def test_password_too_short_on_create(self, integration_client):
+    def test_password_too_short_on_create(self, auth_client):
         """Test that short passwords are rejected when creating users."""
-        integration_client.post(
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
 
-        response = integration_client.post(
+        response = auth_client.post(
             "/api/v1/admin/users",
             json={"username": f"shortpw_{uuid4().hex[:8]}", "password": "short"},
         )
@@ -432,36 +462,49 @@ class TestSecurityEdgeCases:
         assert "at least 8 characters" in response.json()["detail"]
 
     @pytest.mark.integration
-    def test_password_too_short_on_change(self, integration_client):
+    def test_password_too_short_on_change(self, auth_client):
         """Test that short passwords are rejected when changing password."""
-        integration_client.post(
+        # Create test user
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
+        test_username = f"shortchange_{uuid4().hex[:8]}"
+        auth_client.post(
+            "/api/v1/admin/users",
+            json={"username": test_username, "password": "password123"},
+        )
 
-        response = integration_client.post(
+        # Login as test user
+        auth_client.cookies.clear()
+        auth_client.post(
+            "/api/v1/auth/login",
+            json={"username": test_username, "password": "password123"},
+        )
+
+        response = auth_client.post(
             "/api/v1/auth/change-password",
-            json={"current_password": "changeme123", "new_password": "short"},
+            json={"current_password": "password123", "new_password": "short"},
         )
         assert response.status_code == 400
         assert "at least 8 characters" in response.json()["detail"]
 
     @pytest.mark.integration
-    def test_password_too_short_on_reset(self, integration_client):
+    def test_password_too_short_on_reset(self, auth_client):
         """Test that short passwords are rejected when resetting password."""
-        integration_client.post(
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
 
         # Create a test user first
         test_username = f"resetshort_{uuid4().hex[:8]}"
-        integration_client.post(
+        auth_client.post(
             "/api/v1/admin/users",
             json={"username": test_username, "password": "password123"},
         )
 
-        response = integration_client.post(
+        response = auth_client.post(
             f"/api/v1/admin/users/{test_username}/reset-password",
             json={"new_password": "short"},
         )
@@ -469,23 +512,23 @@ class TestSecurityEdgeCases:
         assert "at least 8 characters" in response.json()["detail"]
 
     @pytest.mark.integration
-    def test_duplicate_username_rejected(self, integration_client):
+    def test_duplicate_username_rejected(self, auth_client):
         """Test that duplicate usernames are rejected."""
-        integration_client.post(
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
 
         test_username = f"duplicate_{uuid4().hex[:8]}"
         # Create user first time
-        response1 = integration_client.post(
+        response1 = auth_client.post(
             "/api/v1/admin/users",
             json={"username": test_username, "password": "password123"},
         )
         assert response1.status_code == 200
 
         # Try to create same username again
-        response2 = integration_client.post(
+        response2 = auth_client.post(
             "/api/v1/admin/users",
             json={"username": test_username, "password": "password456"},
         )
@@ -493,14 +536,14 @@ class TestSecurityEdgeCases:
         assert "already exists" in response2.json()["detail"]
 
     @pytest.mark.integration
-    def test_cannot_delete_other_users_api_key(self, integration_client):
+    def test_cannot_delete_other_users_api_key(self, auth_client):
         """Test that users cannot delete API keys owned by other users."""
         # Login as admin and create an API key
-        integration_client.post(
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
-        create_response = integration_client.post(
+        create_response = auth_client.post(
             "/api/v1/auth/keys",
             json={"name": "admin-key"},
         )
@@ -508,253 +551,65 @@ class TestSecurityEdgeCases:
 
         # Create a non-admin user
         test_username = f"nonadmin_{uuid4().hex[:8]}"
-        integration_client.post(
+        auth_client.post(
             "/api/v1/admin/users",
             json={"username": test_username, "password": "password123"},
         )
 
         # Login as non-admin
-        integration_client.cookies.clear()
-        integration_client.post(
+        auth_client.cookies.clear()
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": test_username, "password": "password123"},
         )
 
         # Try to delete admin's API key
-        response = integration_client.delete(f"/api/v1/auth/keys/{admin_key_id}")
+        response = auth_client.delete(f"/api/v1/auth/keys/{admin_key_id}")
         assert response.status_code == 403
         assert "Cannot delete another user's API key" in response.json()["detail"]
 
         # Cleanup: login as admin and delete the key
-        integration_client.cookies.clear()
-        integration_client.post(
+        auth_client.cookies.clear()
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
-        integration_client.delete(f"/api/v1/auth/keys/{admin_key_id}")
+        auth_client.delete(f"/api/v1/auth/keys/{admin_key_id}")
 
     @pytest.mark.integration
-    def test_sessions_invalidated_on_password_change(self, integration_client):
+    def test_sessions_invalidated_on_password_change(self, auth_client):
         """Test that all sessions are invalidated when password is changed."""
         # Create a test user
-        integration_client.post(
+        auth_client.post(
             "/api/v1/auth/login",
             json={"username": "admin", "password": "changeme123"},
         )
         test_username = f"sessiontest_{uuid4().hex[:8]}"
-        integration_client.post(
+        auth_client.post(
             "/api/v1/admin/users",
             json={"username": test_username, "password": "password123"},
         )
 
         # Login as test user
-        integration_client.cookies.clear()
-        login_response = integration_client.post(
+        auth_client.cookies.clear()
+        login_response = auth_client.post(
             "/api/v1/auth/login",
             json={"username": test_username, "password": "password123"},
         )
         assert login_response.status_code == 200
 
         # Verify session works
-        me_response = integration_client.get("/api/v1/auth/me")
+        me_response = auth_client.get("/api/v1/auth/me")
         assert me_response.status_code == 200
 
         # Change password
-        integration_client.post(
+        auth_client.post(
             "/api/v1/auth/change-password",
             json={"current_password": "password123", "new_password": "newpassword123"},
         )
 
         # Old session should be invalidated - try to access /me
         # (note: the change-password call itself may have cleared the session cookie)
-        me_response2 = integration_client.get("/api/v1/auth/me")
-        # This should fail because all sessions were invalidated
-        assert me_response2.status_code == 401
-
-
-class TestSecurityEdgeCases:
-    """Tests for security edge cases and validation."""
-
-    @pytest.mark.integration
-    def test_login_inactive_user(self, integration_client):
-        """Test that inactive users cannot login."""
-        # Login as admin and create a user
-        integration_client.post(
-            "/api/v1/auth/login",
-            json={"username": "admin", "password": "changeme123"},
-        )
-        test_username = f"inactive_{uuid4().hex[:8]}"
-        integration_client.post(
-            "/api/v1/admin/users",
-            json={"username": test_username, "password": "password123"},
-        )
-
-        # Deactivate the user
-        integration_client.put(
-            f"/api/v1/admin/users/{test_username}",
-            json={"is_active": False},
-        )
-
-        # Try to login as inactive user
-        integration_client.cookies.clear()
-        response = integration_client.post(
-            "/api/v1/auth/login",
-            json={"username": test_username, "password": "password123"},
-        )
-        assert response.status_code == 401
-        assert "Invalid username or password" in response.json()["detail"]
-
-    @pytest.mark.integration
-    def test_password_too_short_on_create(self, integration_client):
-        """Test that short passwords are rejected when creating users."""
-        integration_client.post(
-            "/api/v1/auth/login",
-            json={"username": "admin", "password": "changeme123"},
-        )
-
-        response = integration_client.post(
-            "/api/v1/admin/users",
-            json={"username": f"shortpw_{uuid4().hex[:8]}", "password": "short"},
-        )
-        assert response.status_code == 400
-        assert "at least 8 characters" in response.json()["detail"]
-
-    @pytest.mark.integration
-    def test_password_too_short_on_change(self, integration_client):
-        """Test that short passwords are rejected when changing password."""
-        integration_client.post(
-            "/api/v1/auth/login",
-            json={"username": "admin", "password": "changeme123"},
-        )
-
-        response = integration_client.post(
-            "/api/v1/auth/change-password",
-            json={"current_password": "changeme123", "new_password": "short"},
-        )
-        assert response.status_code == 400
-        assert "at least 8 characters" in response.json()["detail"]
-
-    @pytest.mark.integration
-    def test_password_too_short_on_reset(self, integration_client):
-        """Test that short passwords are rejected when resetting password."""
-        integration_client.post(
-            "/api/v1/auth/login",
-            json={"username": "admin", "password": "changeme123"},
-        )
-
-        # Create a test user first
-        test_username = f"resetshort_{uuid4().hex[:8]}"
-        integration_client.post(
-            "/api/v1/admin/users",
-            json={"username": test_username, "password": "password123"},
-        )
-
-        response = integration_client.post(
-            f"/api/v1/admin/users/{test_username}/reset-password",
-            json={"new_password": "short"},
-        )
-        assert response.status_code == 400
-        assert "at least 8 characters" in response.json()["detail"]
-
-    @pytest.mark.integration
-    def test_duplicate_username_rejected(self, integration_client):
-        """Test that duplicate usernames are rejected."""
-        integration_client.post(
-            "/api/v1/auth/login",
-            json={"username": "admin", "password": "changeme123"},
-        )
-
-        test_username = f"duplicate_{uuid4().hex[:8]}"
-        # Create user first time
-        response1 = integration_client.post(
-            "/api/v1/admin/users",
-            json={"username": test_username, "password": "password123"},
-        )
-        assert response1.status_code == 200
-
-        # Try to create same username again
-        response2 = integration_client.post(
-            "/api/v1/admin/users",
-            json={"username": test_username, "password": "password456"},
-        )
-        assert response2.status_code == 409
-        assert "already exists" in response2.json()["detail"]
-
-    @pytest.mark.integration
-    def test_cannot_delete_other_users_api_key(self, integration_client):
-        """Test that users cannot delete API keys owned by other users."""
-        # Login as admin and create an API key
-        integration_client.post(
-            "/api/v1/auth/login",
-            json={"username": "admin", "password": "changeme123"},
-        )
-        create_response = integration_client.post(
-            "/api/v1/auth/keys",
-            json={"name": "admin-key"},
-        )
-        admin_key_id = create_response.json()["id"]
-
-        # Create a non-admin user
-        test_username = f"nonadmin_{uuid4().hex[:8]}"
-        integration_client.post(
-            "/api/v1/admin/users",
-            json={"username": test_username, "password": "password123"},
-        )
-
-        # Login as non-admin
-        integration_client.cookies.clear()
-        integration_client.post(
-            "/api/v1/auth/login",
-            json={"username": test_username, "password": "password123"},
-        )
-
-        # Try to delete admin's API key
-        response = integration_client.delete(f"/api/v1/auth/keys/{admin_key_id}")
-        assert response.status_code == 403
-        assert "Cannot delete another user's API key" in response.json()["detail"]
-
-        # Cleanup: login as admin and delete the key
-        integration_client.cookies.clear()
-        integration_client.post(
-            "/api/v1/auth/login",
-            json={"username": "admin", "password": "changeme123"},
-        )
-        integration_client.delete(f"/api/v1/auth/keys/{admin_key_id}")
-
-    @pytest.mark.integration
-    def test_sessions_invalidated_on_password_change(self, integration_client):
-        """Test that all sessions are invalidated when password is changed."""
-        # Create a test user
-        integration_client.post(
-            "/api/v1/auth/login",
-            json={"username": "admin", "password": "changeme123"},
-        )
-        test_username = f"sessiontest_{uuid4().hex[:8]}"
-        integration_client.post(
-            "/api/v1/admin/users",
-            json={"username": test_username, "password": "password123"},
-        )
-
-        # Login as test user
-        integration_client.cookies.clear()
-        login_response = integration_client.post(
-            "/api/v1/auth/login",
-            json={"username": test_username, "password": "password123"},
-        )
-        assert login_response.status_code == 200
-
-        # Verify session works
-        me_response = integration_client.get("/api/v1/auth/me")
-        assert me_response.status_code == 200
-
-        # Change password
-        integration_client.post(
-            "/api/v1/auth/change-password",
-            json={"current_password": "password123", "new_password": "newpassword123"},
-        )
-
-        # Old session should be invalidated - try to access /me
-        # (note: the change-password call itself may have cleared the session cookie)
-        me_response2 = integration_client.get("/api/v1/auth/me")
+        me_response2 = auth_client.get("/api/v1/auth/me")
         # This should fail because all sessions were invalidated
         assert me_response2.status_code == 401

backend/tests/integration/test_concurrent_operations.py

@@ -0,0 +1,737 @@
+"""
+Integration tests for concurrent upload and download operations.
+
+Tests cover:
+- Concurrent uploads of different files
+- Concurrent uploads of same file (deduplication race)
+- Concurrent downloads of same artifact
+- Concurrent downloads of different artifacts
+- Mixed concurrent uploads and downloads
+- Data corruption prevention under concurrency
+"""
+
+import pytest
+import io
+import os
+from concurrent.futures import ThreadPoolExecutor, as_completed
+from tests.factories import (
+    compute_sha256,
+    upload_test_file,
+    generate_content_with_hash,
+)
+
+
+def get_api_key(integration_client):
+    """Create an API key for concurrent test workers."""
+    import uuid
+    response = integration_client.post(
+        "/api/v1/auth/keys",
+        json={"name": f"concurrent-test-{uuid.uuid4().hex[:8]}"},
+    )
+    if response.status_code == 200:
+        return response.json()["key"]
+    return None
+
+
+class TestConcurrentUploads:
+    """Tests for concurrent upload operations."""
+
+    @pytest.mark.integration
+    @pytest.mark.concurrent
+    def test_2_concurrent_uploads_different_files(self, integration_client, test_package):
+        """Test 2 concurrent uploads of different files."""
+        project, package = test_package
+        api_key = get_api_key(integration_client)
+        assert api_key, "Failed to create API key"
+
+        files_data = [
+            generate_content_with_hash(1024, seed=i) for i in range(2)
+        ]
+
+        results = []
+        errors = []
+
+        def upload_worker(idx, content, expected_hash):
+            try:
+                from httpx import Client
+                base_url = os.environ.get("ORCHARD_TEST_URL", "http://localhost:8080")
+
+                with Client(base_url=base_url, timeout=60.0) as client:
+                    files = {
+                        "file": (f"file-{idx}.bin", io.BytesIO(content), "application/octet-stream")
+                    }
+                    response = client.post(
+                        f"/api/v1/project/{project}/{package}/upload",
+                        files=files,
+                        data={"tag": f"concurrent-{idx}"},
+                        headers={"Authorization": f"Bearer {api_key}"},
+                    )
+                    if response.status_code == 200:
+                        result = response.json()
+                        results.append((idx, result, expected_hash))
+                    else:
+                        errors.append(f"Worker {idx}: Status {response.status_code}: {response.text}")
+            except Exception as e:
+                errors.append(f"Worker {idx}: {str(e)}")
+
+        with ThreadPoolExecutor(max_workers=2) as executor:
+            futures = [
+                executor.submit(upload_worker, i, content, hash)
+                for i, (content, hash) in enumerate(files_data)
+            ]
+            for future in as_completed(futures):
+                pass
+
+        assert len(errors) == 0, f"Errors: {errors}"
+        assert len(results) == 2
+
+        # Verify each upload returned correct artifact_id
+        for idx, result, expected_hash in results:
+            assert result["artifact_id"] == expected_hash
+
+    @pytest.mark.integration
+    @pytest.mark.concurrent
+    def test_5_concurrent_uploads_different_files(self, integration_client, test_package):
+        """Test 5 concurrent uploads of different files."""
+        project, package = test_package
+        api_key = get_api_key(integration_client)
+        assert api_key, "Failed to create API key"
+
+        num_files = 5
+        files_data = [
+            generate_content_with_hash(2048, seed=100 + i) for i in range(num_files)
+        ]
+
+        results = []
+        errors = []
+
+        def upload_worker(idx, content, expected_hash):
+            try:
+                from httpx import Client
+                base_url = os.environ.get("ORCHARD_TEST_URL", "http://localhost:8080")
+
+                with Client(base_url=base_url, timeout=60.0) as client:
+                    files = {
+                        "file": (f"file-{idx}.bin", io.BytesIO(content), "application/octet-stream")
+                    }
+                    response = client.post(
+                        f"/api/v1/project/{project}/{package}/upload",
+                        files=files,
+                        data={"tag": f"concurrent5-{idx}"},
+                        headers={"Authorization": f"Bearer {api_key}"},
+                    )
+                    if response.status_code == 200:
+                        result = response.json()
+                        results.append((idx, result, expected_hash))
+                    else:
+                        errors.append(f"Worker {idx}: Status {response.status_code}")
+            except Exception as e:
+                errors.append(f"Worker {idx}: {str(e)}")
+
+        with ThreadPoolExecutor(max_workers=num_files) as executor:
+            futures = [
+                executor.submit(upload_worker, i, content, hash)
+                for i, (content, hash) in enumerate(files_data)
+            ]
+            for future in as_completed(futures):
+                pass
+
+        assert len(errors) == 0, f"Errors: {errors}"
+        assert len(results) == num_files
+
+        # Verify all uploads have unique artifact_ids
+        artifact_ids = set(r[1]["artifact_id"] for r in results)
+        assert len(artifact_ids) == num_files
+
+    @pytest.mark.integration
+    @pytest.mark.concurrent
+    def test_10_concurrent_uploads_different_files(self, integration_client, test_package):
+        """Test 10 concurrent uploads of different files."""
+        project, package = test_package
+        api_key = get_api_key(integration_client)
+        assert api_key, "Failed to create API key"
+
+        num_files = 10
+        files_data = [
+            generate_content_with_hash(1024, seed=200 + i) for i in range(num_files)
+        ]
+
+        results = []
+        errors = []
+
+        def upload_worker(idx, content, expected_hash):
+            try:
+                from httpx import Client
+                base_url = os.environ.get("ORCHARD_TEST_URL", "http://localhost:8080")
+
+                with Client(base_url=base_url, timeout=60.0) as client:
+                    files = {
+                        "file": (f"file-{idx}.bin", io.BytesIO(content), "application/octet-stream")
+                    }
+                    response = client.post(
+                        f"/api/v1/project/{project}/{package}/upload",
+                        files=files,
+                        data={"tag": f"concurrent10-{idx}"},
+                        headers={"Authorization": f"Bearer {api_key}"},
+                    )
+                    if response.status_code == 200:
+                        result = response.json()
+                        results.append((idx, result, expected_hash))
+                    else:
+                        errors.append(f"Worker {idx}: Status {response.status_code}")
+            except Exception as e:
+                errors.append(f"Worker {idx}: {str(e)}")
+
+        with ThreadPoolExecutor(max_workers=num_files) as executor:
+            futures = [
+                executor.submit(upload_worker, i, content, hash)
+                for i, (content, hash) in enumerate(files_data)
+            ]
+            for future in as_completed(futures):
+                pass
+
+        assert len(errors) == 0, f"Errors: {errors}"
+        assert len(results) == num_files
+
+    @pytest.mark.integration
+    @pytest.mark.concurrent
+    def test_concurrent_uploads_same_file_deduplication(self, integration_client, test_package):
+        """Test concurrent uploads of same file handle deduplication correctly."""
+        project, package = test_package
+        api_key = get_api_key(integration_client)
+        assert api_key, "Failed to create API key"
+
+        content, expected_hash = generate_content_with_hash(4096, seed=999)
+        num_concurrent = 5
+
+        results = []
+        errors = []
+
+        def upload_worker(idx):
+            try:
+                from httpx import Client
+                base_url = os.environ.get("ORCHARD_TEST_URL", "http://localhost:8080")
+
+                with Client(base_url=base_url, timeout=60.0) as client:
+                    files = {
+                        "file": (f"same-{idx}.bin", io.BytesIO(content), "application/octet-stream")
+                    }
+                    response = client.post(
+                        f"/api/v1/project/{project}/{package}/upload",
+                        files=files,
+                        data={"tag": f"dedup-{idx}"},
+                        headers={"Authorization": f"Bearer {api_key}"},
+                    )
+                    if response.status_code == 200:
+                        results.append(response.json())
+                    else:
+                        errors.append(f"Worker {idx}: Status {response.status_code}")
+            except Exception as e:
+                errors.append(f"Worker {idx}: {str(e)}")
+
+        with ThreadPoolExecutor(max_workers=num_concurrent) as executor:
+            futures = [executor.submit(upload_worker, i) for i in range(num_concurrent)]
+            for future in as_completed(futures):
+                pass
+
+        assert len(errors) == 0, f"Errors: {errors}"
+        assert len(results) == num_concurrent
+
+        # All should have same artifact_id
+        artifact_ids = set(r["artifact_id"] for r in results)
+        assert len(artifact_ids) == 1
+        assert expected_hash in artifact_ids
+
+        # Verify final ref_count equals number of uploads
+        response = integration_client.get(f"/api/v1/artifact/{expected_hash}")
+        assert response.status_code == 200
+        assert response.json()["ref_count"] == num_concurrent
+
+    @pytest.mark.integration
+    @pytest.mark.concurrent
+    def test_concurrent_uploads_to_different_packages(self, integration_client, test_project, unique_test_id):
+        """Test concurrent uploads to different packages."""
+        project = test_project
+        api_key = get_api_key(integration_client)
+        assert api_key, "Failed to create API key"
+
+        num_packages = 3
+        package_names = []
+
+        # Create multiple packages
+        for i in range(num_packages):
+            pkg_name = f"pkg-{unique_test_id}-{i}"
+            response = integration_client.post(
+                f"/api/v1/project/{project}/packages",
+                json={"name": pkg_name, "description": f"Package {i}"},
+            )
+            assert response.status_code == 200
+            package_names.append(pkg_name)
+
+        files_data = [
+            generate_content_with_hash(1024, seed=300 + i) for i in range(num_packages)
+        ]
+
+        results = []
+        errors = []
+
+        def upload_worker(idx, package, content, expected_hash):
+            try:
+                from httpx import Client
+                base_url = os.environ.get("ORCHARD_TEST_URL", "http://localhost:8080")
+
+                with Client(base_url=base_url, timeout=60.0) as client:
+                    files = {
+                        "file": (f"file-{idx}.bin", io.BytesIO(content), "application/octet-stream")
+                    }
+                    response = client.post(
+                        f"/api/v1/project/{project}/{package}/upload",
+                        files=files,
+                        data={"tag": "latest"},
+                        headers={"Authorization": f"Bearer {api_key}"},
+                    )
+                    if response.status_code == 200:
+                        result = response.json()
+                        results.append((package, result, expected_hash))
+                    else:
+                        errors.append(f"Worker {idx}: Status {response.status_code}")
+            except Exception as e:
+                errors.append(f"Worker {idx}: {str(e)}")
+
+        with ThreadPoolExecutor(max_workers=num_packages) as executor:
+            futures = [
+                executor.submit(upload_worker, i, package_names[i], content, hash)
+                for i, (content, hash) in enumerate(files_data)
+            ]
+            for future in as_completed(futures):
+                pass
+
+        assert len(errors) == 0, f"Errors: {errors}"
+        assert len(results) == num_packages
+
+
+class TestConcurrentDownloads:
+    """Tests for concurrent download operations."""
+
+    @pytest.mark.integration
+    @pytest.mark.concurrent
+    def test_2_concurrent_downloads_same_artifact(self, integration_client, test_package):
+        """Test 2 concurrent downloads of same artifact."""
+        project, package = test_package
+        content, expected_hash = generate_content_with_hash(2048, seed=400)
+
+        # Upload first
+        upload_test_file(integration_client, project, package, content, tag="download-test")
+
+        results = []
+        errors = []
+
+        def download_worker(idx):
+            try:
+                from httpx import Client
+                base_url = os.environ.get("ORCHARD_TEST_URL", "http://localhost:8080")
+
+                with Client(base_url=base_url, timeout=60.0) as client:
+                    response = client.get(
+                        f"/api/v1/project/{project}/{package}/+/download-test",
+                        params={"mode": "proxy"},
+                    )
+                    if response.status_code == 200:
+                        results.append((idx, response.content))
+                    else:
+                        errors.append(f"Worker {idx}: Status {response.status_code}")
+            except Exception as e:
+                errors.append(f"Worker {idx}: {str(e)}")
+
+        with ThreadPoolExecutor(max_workers=2) as executor:
+            futures = [executor.submit(download_worker, i) for i in range(2)]
+            for future in as_completed(futures):
+                pass
+
+        assert len(errors) == 0, f"Errors: {errors}"
+        assert len(results) == 2
+
+        # All downloads should match original
+        for idx, downloaded in results:
+            assert downloaded == content
+
+    @pytest.mark.integration
+    @pytest.mark.concurrent
+    def test_5_concurrent_downloads_same_artifact(self, integration_client, test_package):
+        """Test 5 concurrent downloads of same artifact."""
+        project, package = test_package
+        content, expected_hash = generate_content_with_hash(4096, seed=500)
+
+        upload_test_file(integration_client, project, package, content, tag="download5-test")
+
+        num_downloads = 5
+        results = []
+        errors = []
+
+        def download_worker(idx):
+            try:
+                from httpx import Client
+                base_url = os.environ.get("ORCHARD_TEST_URL", "http://localhost:8080")
+
+                with Client(base_url=base_url, timeout=60.0) as client:
+                    response = client.get(
+                        f"/api/v1/project/{project}/{package}/+/download5-test",
+                        params={"mode": "proxy"},
+                    )
+                    if response.status_code == 200:
+                        results.append((idx, response.content))
+                    else:
+                        errors.append(f"Worker {idx}: Status {response.status_code}")
+            except Exception as e:
+                errors.append(f"Worker {idx}: {str(e)}")
+
+        with ThreadPoolExecutor(max_workers=num_downloads) as executor:
+            futures = [executor.submit(download_worker, i) for i in range(num_downloads)]
+            for future in as_completed(futures):
+                pass
+
+        assert len(errors) == 0, f"Errors: {errors}"
+        assert len(results) == num_downloads
+
+        for idx, downloaded in results:
+            assert downloaded == content
+
+    @pytest.mark.integration
+    @pytest.mark.concurrent
+    def test_10_concurrent_downloads_same_artifact(self, integration_client, test_package):
+        """Test 10 concurrent downloads of same artifact."""
+        project, package = test_package
+        content, expected_hash = generate_content_with_hash(8192, seed=600)
+
+        upload_test_file(integration_client, project, package, content, tag="download10-test")
+
+        num_downloads = 10
+        results = []
+        errors = []
+
+        def download_worker(idx):
+            try:
+                from httpx import Client
+                base_url = os.environ.get("ORCHARD_TEST_URL", "http://localhost:8080")
+
+                with Client(base_url=base_url, timeout=60.0) as client:
+                    response = client.get(
+                        f"/api/v1/project/{project}/{package}/+/download10-test",
+                        params={"mode": "proxy"},
+                    )
+                    if response.status_code == 200:
+                        results.append((idx, response.content))
+                    else:
+                        errors.append(f"Worker {idx}: Status {response.status_code}")
+            except Exception as e:
+                errors.append(f"Worker {idx}: {str(e)}")
+
+        with ThreadPoolExecutor(max_workers=num_downloads) as executor:
+            futures = [executor.submit(download_worker, i) for i in range(num_downloads)]
+            for future in as_completed(futures):
+                pass
+
+        assert len(errors) == 0, f"Errors: {errors}"
+        assert len(results) == num_downloads
+
+        for idx, downloaded in results:
+            assert downloaded == content
+
+    @pytest.mark.integration
+    @pytest.mark.concurrent
+    def test_concurrent_downloads_different_artifacts(self, integration_client, test_package):
+        """Test concurrent downloads of different artifacts."""
+        project, package = test_package
+
+        # Upload multiple files
+        num_files = 5
+        uploads = []
+        for i in range(num_files):
+            content, expected_hash = generate_content_with_hash(1024, seed=700 + i)
+            upload_test_file(
+                integration_client, project, package, content,
+                tag=f"multi-download-{i}"
+            )
+            uploads.append((f"multi-download-{i}", content))
+
+        results = []
+        errors = []
+
+        def download_worker(tag, expected_content):
+            try:
+                from httpx import Client
+                base_url = os.environ.get("ORCHARD_TEST_URL", "http://localhost:8080")
+
+                with Client(base_url=base_url, timeout=60.0) as client:
+                    response = client.get(
+                        f"/api/v1/project/{project}/{package}/+/{tag}",
+                        params={"mode": "proxy"},
+                    )
+                    if response.status_code == 200:
+                        results.append((tag, response.content, expected_content))
+                    else:
+                        errors.append(f"Tag {tag}: Status {response.status_code}")
+            except Exception as e:
+                errors.append(f"Tag {tag}: {str(e)}")
+
+        with ThreadPoolExecutor(max_workers=num_files) as executor:
+            futures = [
+                executor.submit(download_worker, tag, content)
+                for tag, content in uploads
+            ]
+            for future in as_completed(futures):
+                pass
+
+        assert len(errors) == 0, f"Errors: {errors}"
+        assert len(results) == num_files
+
+        for tag, downloaded, expected in results:
+            assert downloaded == expected, f"Content mismatch for {tag}"
+
+
+class TestMixedConcurrentOperations:
+    """Tests for mixed concurrent upload and download operations."""
+
+    @pytest.mark.integration
+    @pytest.mark.concurrent
+    def test_upload_while_download_in_progress(self, integration_client, test_package):
+        """Test uploading while a download is in progress."""
+        project, package = test_package
+        api_key = get_api_key(integration_client)
+        assert api_key, "Failed to create API key"
+
+        # Upload initial content
+        content1, hash1 = generate_content_with_hash(10240, seed=800)  # 10KB
+        upload_test_file(integration_client, project, package, content1, tag="initial")
+
+        # New content for upload during download
+        content2, hash2 = generate_content_with_hash(10240, seed=801)
+
+        results = {"downloads": [], "uploads": []}
+        errors = []
+
+        def download_worker():
+            try:
+                from httpx import Client
+                base_url = os.environ.get("ORCHARD_TEST_URL", "http://localhost:8080")
+
+                with Client(base_url=base_url, timeout=60.0) as client:
+                    response = client.get(
+                        f"/api/v1/project/{project}/{package}/+/initial",
+                        params={"mode": "proxy"},
+                    )
+                    if response.status_code == 200:
+                        results["downloads"].append(response.content)
+                    else:
+                        errors.append(f"Download: Status {response.status_code}")
+            except Exception as e:
+                errors.append(f"Download: {str(e)}")
+
+        def upload_worker():
+            try:
+                from httpx import Client
+                base_url = os.environ.get("ORCHARD_TEST_URL", "http://localhost:8080")
+
+                with Client(base_url=base_url, timeout=60.0) as client:
+                    files = {
+                        "file": ("new.bin", io.BytesIO(content2), "application/octet-stream")
+                    }
+                    response = client.post(
+                        f"/api/v1/project/{project}/{package}/upload",
+                        files=files,
+                        data={"tag": "during-download"},
+                        headers={"Authorization": f"Bearer {api_key}"},
+                    )
+                    if response.status_code == 200:
+                        results["uploads"].append(response.json())
+                    else:
+                        errors.append(f"Upload: Status {response.status_code}")
+            except Exception as e:
+                errors.append(f"Upload: {str(e)}")
+
+        with ThreadPoolExecutor(max_workers=2) as executor:
+            futures = [
+                executor.submit(download_worker),
+                executor.submit(upload_worker),
+            ]
+            for future in as_completed(futures):
+                pass
+
+        assert len(errors) == 0, f"Errors: {errors}"
+        assert len(results["downloads"]) == 1
+        assert len(results["uploads"]) == 1
+
+        # Verify download got correct content
+        assert results["downloads"][0] == content1
+
+        # Verify upload succeeded
+        assert results["uploads"][0]["artifact_id"] == hash2
+
+    @pytest.mark.integration
+    @pytest.mark.concurrent
+    def test_multiple_uploads_and_downloads_simultaneously(self, integration_client, test_package):
+        """Test multiple uploads and downloads running simultaneously."""
+        project, package = test_package
+        api_key = get_api_key(integration_client)
+        assert api_key, "Failed to create API key"
+
+        # Pre-upload some files for downloading
+        existing_files = []
+        for i in range(3):
+            content, hash = generate_content_with_hash(2048, seed=900 + i)
+            upload_test_file(integration_client, project, package, content, tag=f"existing-{i}")
+            existing_files.append((f"existing-{i}", content))
+
+        # New files for uploading
+        new_files = [
+            generate_content_with_hash(2048, seed=910 + i) for i in range(3)
+        ]
+
+        results = {"downloads": [], "uploads": []}
+        errors = []
+
+        def download_worker(tag, expected):
+            try:
+                from httpx import Client
+                base_url = os.environ.get("ORCHARD_TEST_URL", "http://localhost:8080")
+
+                with Client(base_url=base_url, timeout=60.0) as client:
+                    response = client.get(
+                        f"/api/v1/project/{project}/{package}/+/{tag}",
+                        params={"mode": "proxy"},
+                    )
+                    if response.status_code == 200:
+                        results["downloads"].append((tag, response.content, expected))
+                    else:
+                        errors.append(f"Download {tag}: Status {response.status_code}")
+            except Exception as e:
+                errors.append(f"Download {tag}: {str(e)}")
+
+        def upload_worker(idx, content, expected_hash):
+            try:
+                from httpx import Client
+                base_url = os.environ.get("ORCHARD_TEST_URL", "http://localhost:8080")
+
+                with Client(base_url=base_url, timeout=60.0) as client:
+                    files = {
+                        "file": (f"new-{idx}.bin", io.BytesIO(content), "application/octet-stream")
+                    }
+                    response = client.post(
+                        f"/api/v1/project/{project}/{package}/upload",
+                        files=files,
+                        data={"tag": f"new-{idx}"},
+                        headers={"Authorization": f"Bearer {api_key}"},
+                    )
+                    if response.status_code == 200:
+                        results["uploads"].append((idx, response.json(), expected_hash))
+                    else:
+                        errors.append(f"Upload {idx}: Status {response.status_code}")
+            except Exception as e:
+                errors.append(f"Upload {idx}: {str(e)}")
+
+        with ThreadPoolExecutor(max_workers=6) as executor:
+            futures = []
+
+            # Submit downloads
+            for tag, content in existing_files:
+                futures.append(executor.submit(download_worker, tag, content))
+
+            # Submit uploads
+            for i, (content, hash) in enumerate(new_files):
+                futures.append(executor.submit(upload_worker, i, content, hash))
+
+            for future in as_completed(futures):
+                pass
+
+        assert len(errors) == 0, f"Errors: {errors}"
+        assert len(results["downloads"]) == 3
+        assert len(results["uploads"]) == 3
+
+        # Verify downloads
+        for tag, downloaded, expected in results["downloads"]:
+            assert downloaded == expected, f"Download mismatch for {tag}"
+
+        # Verify uploads
+        for idx, result, expected_hash in results["uploads"]:
+            assert result["artifact_id"] == expected_hash
+
+    @pytest.mark.integration
+    @pytest.mark.concurrent
+    def test_no_data_corruption_under_concurrency(self, integration_client, test_package):
+        """Test that no data corruption occurs under concurrent operations."""
+        project, package = test_package
+        api_key = get_api_key(integration_client)
+        assert api_key, "Failed to create API key"
+
+        # Create content with recognizable patterns
+        num_files = 5
+        files_data = []
+        for i in range(num_files):
+            # Each file has unique repeating pattern for easy corruption detection
+            pattern = bytes([i] * 256)
+            content = pattern * 40  # 10KB each
+            hash = compute_sha256(content)
+            files_data.append((content, hash))
+
+        results = []
+        errors = []
+
+        def upload_and_verify(idx, content, expected_hash):
+            try:
+                from httpx import Client
+                base_url = os.environ.get("ORCHARD_TEST_URL", "http://localhost:8080")
+
+                with Client(base_url=base_url, timeout=60.0) as client:
+                    # Upload
+                    files = {
+                        "file": (f"pattern-{idx}.bin", io.BytesIO(content), "application/octet-stream")
+                    }
+                    upload_resp = client.post(
+                        f"/api/v1/project/{project}/{package}/upload",
+                        files=files,
+                        data={"tag": f"pattern-{idx}"},
+                        headers={"Authorization": f"Bearer {api_key}"},
+                    )
+                    if upload_resp.status_code != 200:
+                        errors.append(f"Upload {idx}: Status {upload_resp.status_code}")
+                        return
+
+                    upload_result = upload_resp.json()
+                    if upload_result["artifact_id"] != expected_hash:
+                        errors.append(f"Upload {idx}: Hash mismatch")
+                        return
+
+                    # Immediately download and verify
+                    download_resp = client.get(
+                        f"/api/v1/project/{project}/{package}/+/pattern-{idx}",
+                        params={"mode": "proxy"},
+                    )
+                    if download_resp.status_code != 200:
+                        errors.append(f"Download {idx}: Status {download_resp.status_code}")
+                        return
+
+                    if download_resp.content != content:
+                        errors.append(f"Worker {idx}: DATA CORRUPTION DETECTED")
+                        return
+
+                    # Verify the downloaded content hash
+                    downloaded_hash = compute_sha256(download_resp.content)
+                    if downloaded_hash != expected_hash:
+                        errors.append(f"Worker {idx}: Hash verification failed")
+                        return
+
+                    results.append(idx)
+
+            except Exception as e:
+                errors.append(f"Worker {idx}: {str(e)}")
+
+        with ThreadPoolExecutor(max_workers=num_files) as executor:
+            futures = [
+                executor.submit(upload_and_verify, i, content, hash)
+                for i, (content, hash) in enumerate(files_data)
+            ]
+            for future in as_completed(futures):
+                pass
+
+        assert len(errors) == 0, f"Errors: {errors}"
+        assert len(results) == num_files

backend/tests/integration/test_error_handling.py

@@ -0,0 +1,322 @@
+"""
+Integration tests for error handling in upload and download operations.
+
+Tests cover:
+- Timeout handling
+- Invalid request handling
+- Resource cleanup on failures
+- Graceful error responses
+"""
+
+import pytest
+import io
+import time
+from tests.factories import (
+    compute_sha256,
+    upload_test_file,
+    generate_content_with_hash,
+)
+
+
+class TestUploadErrorHandling:
+    """Tests for upload error handling."""
+
+    @pytest.mark.integration
+    def test_upload_to_nonexistent_project_returns_404(
+        self, integration_client, unique_test_id
+    ):
+        """Test upload to nonexistent project returns 404."""
+        content = b"test content for nonexistent project"
+
+        files = {"file": ("test.bin", io.BytesIO(content), "application/octet-stream")}
+        response = integration_client.post(
+            f"/api/v1/project/nonexistent-project-{unique_test_id}/nonexistent-pkg/upload",
+            files=files,
+        )
+        assert response.status_code == 404
+
+    @pytest.mark.integration
+    def test_upload_to_nonexistent_package_returns_404(
+        self, integration_client, test_project, unique_test_id
+    ):
+        """Test upload to nonexistent package returns 404."""
+        content = b"test content for nonexistent package"
+
+        files = {"file": ("test.bin", io.BytesIO(content), "application/octet-stream")}
+        response = integration_client.post(
+            f"/api/v1/project/{test_project}/nonexistent-package-{unique_test_id}/upload",
+            files=files,
+        )
+        assert response.status_code == 404
+
+    @pytest.mark.integration
+    def test_upload_empty_file_rejected(self, integration_client, test_package):
+        """Test empty file upload is rejected."""
+        project, package = test_package
+
+        files = {"file": ("empty.bin", io.BytesIO(b""), "application/octet-stream")}
+        response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+        )
+        assert response.status_code in [400, 422]
+
+    @pytest.mark.integration
+    def test_upload_missing_file_returns_422(self, integration_client, test_package):
+        """Test upload without file field returns 422."""
+        project, package = test_package
+
+        response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            data={"tag": "no-file-provided"},
+        )
+        assert response.status_code == 422
+
+    @pytest.mark.integration
+    def test_upload_invalid_checksum_format_returns_400(
+        self, integration_client, test_package
+    ):
+        """Test upload with invalid checksum format returns 400."""
+        project, package = test_package
+        content = b"checksum format test"
+
+        files = {"file": ("test.bin", io.BytesIO(content), "application/octet-stream")}
+        response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+            headers={"X-Checksum-SHA256": "invalid-hash-format"},
+        )
+        assert response.status_code == 400
+
+    @pytest.mark.integration
+    def test_upload_checksum_mismatch_returns_422(
+        self, integration_client, test_package
+    ):
+        """Test upload with mismatched checksum returns 422."""
+        project, package = test_package
+        content = b"checksum mismatch test"
+        wrong_hash = "0" * 64  # Valid format but wrong hash
+
+        files = {"file": ("test.bin", io.BytesIO(content), "application/octet-stream")}
+        response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+            headers={"X-Checksum-SHA256": wrong_hash},
+        )
+        assert response.status_code == 422
+
+    @pytest.mark.integration
+    def test_upload_with_correct_checksum_succeeds(
+        self, integration_client, test_package
+    ):
+        """Test upload with correct checksum succeeds."""
+        project, package = test_package
+        content = b"correct checksum test"
+        correct_hash = compute_sha256(content)
+
+        files = {"file": ("test.bin", io.BytesIO(content), "application/octet-stream")}
+        response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+            headers={"X-Checksum-SHA256": correct_hash},
+        )
+        assert response.status_code == 200
+        assert response.json()["artifact_id"] == correct_hash
+
+
+class TestDownloadErrorHandling:
+    """Tests for download error handling."""
+
+    @pytest.mark.integration
+    def test_download_nonexistent_tag_returns_404(
+        self, integration_client, test_package
+    ):
+        """Test download of nonexistent tag returns 404."""
+        project, package = test_package
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/nonexistent-tag-xyz"
+        )
+        assert response.status_code == 404
+
+    @pytest.mark.integration
+    def test_download_nonexistent_artifact_returns_404(
+        self, integration_client, test_package
+    ):
+        """Test download of nonexistent artifact ID returns 404."""
+        project, package = test_package
+        fake_hash = "a" * 64
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/artifact:{fake_hash}"
+        )
+        assert response.status_code == 404
+
+    @pytest.mark.integration
+    def test_download_invalid_artifact_id_format(
+        self, integration_client, test_package
+    ):
+        """Test download with invalid artifact ID format."""
+        project, package = test_package
+
+        # Too short
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/artifact:abc123"
+        )
+        assert response.status_code == 404
+
+    @pytest.mark.integration
+    def test_download_from_nonexistent_project_returns_404(
+        self, integration_client, unique_test_id
+    ):
+        """Test download from nonexistent project returns 404."""
+        response = integration_client.get(
+            f"/api/v1/project/nonexistent-{unique_test_id}/pkg/+/tag"
+        )
+        assert response.status_code == 404
+
+    @pytest.mark.integration
+    def test_download_from_nonexistent_package_returns_404(
+        self, integration_client, test_project, unique_test_id
+    ):
+        """Test download from nonexistent package returns 404."""
+        response = integration_client.get(
+            f"/api/v1/project/{test_project}/nonexistent-{unique_test_id}/+/tag"
+        )
+        assert response.status_code == 404
+
+
+class TestTimeoutBehavior:
+    """Tests for timeout behavior (integration level)."""
+
+    @pytest.mark.integration
+    @pytest.mark.slow
+    def test_large_upload_completes_within_reasonable_time(
+        self, integration_client, test_package, sized_content
+    ):
+        """Test that a 10MB upload completes within reasonable time."""
+        project, package = test_package
+        content, expected_hash = sized_content(10 * 1024 * 1024, seed=999)  # 10MB
+
+        start_time = time.time()
+        result = upload_test_file(
+            integration_client, project, package, content, tag="timeout-test"
+        )
+        elapsed = time.time() - start_time
+
+        assert result["artifact_id"] == expected_hash
+        # Should complete within 60 seconds for 10MB on local docker
+        assert elapsed < 60, f"Upload took too long: {elapsed:.2f}s"
+
+    @pytest.mark.integration
+    @pytest.mark.slow
+    def test_large_download_completes_within_reasonable_time(
+        self, integration_client, test_package, sized_content
+    ):
+        """Test that a 10MB download completes within reasonable time."""
+        project, package = test_package
+        content, expected_hash = sized_content(10 * 1024 * 1024, seed=998)  # 10MB
+
+        # First upload
+        upload_test_file(
+            integration_client, project, package, content, tag="download-timeout-test"
+        )
+
+        # Then download and time it
+        start_time = time.time()
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/download-timeout-test",
+            params={"mode": "proxy"},
+        )
+        elapsed = time.time() - start_time
+
+        assert response.status_code == 200
+        assert len(response.content) == len(content)
+        # Should complete within 60 seconds for 10MB on local docker
+        assert elapsed < 60, f"Download took too long: {elapsed:.2f}s"
+
+
+class TestResourceCleanup:
+    """Tests for proper resource cleanup on failures.
+
+    Note: More comprehensive cleanup tests are in test_upload_download_api.py
+    (TestUploadFailureCleanup class) including S3 object cleanup verification.
+    """
+
+    @pytest.mark.integration
+    def test_checksum_mismatch_no_orphaned_artifact(
+        self, integration_client, test_package, unique_test_id
+    ):
+        """Test checksum mismatch doesn't leave orphaned artifact."""
+        project, package = test_package
+        # Use unique content to ensure artifact doesn't exist from prior tests
+        content = f"checksum mismatch orphan test {unique_test_id}".encode()
+        wrong_hash = "0" * 64
+        actual_hash = compute_sha256(content)
+
+        # Verify artifact doesn't exist before test
+        pre_check = integration_client.get(f"/api/v1/artifact/{actual_hash}")
+        assert pre_check.status_code == 404, "Artifact should not exist before test"
+
+        files = {"file": ("test.bin", io.BytesIO(content), "application/octet-stream")}
+        response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+            headers={"X-Checksum-SHA256": wrong_hash},
+        )
+        assert response.status_code == 422
+
+        # Verify no artifact was created with either hash
+        response1 = integration_client.get(f"/api/v1/artifact/{wrong_hash}")
+        response2 = integration_client.get(f"/api/v1/artifact/{actual_hash}")
+        assert response1.status_code == 404
+        assert response2.status_code == 404
+
+
+class TestGracefulErrorResponses:
+    """Tests for graceful and informative error responses."""
+
+    @pytest.mark.integration
+    def test_404_response_has_detail_message(
+        self, integration_client, test_package
+    ):
+        """Test 404 responses include a detail message."""
+        project, package = test_package
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/nonexistent-tag"
+        )
+        assert response.status_code == 404
+        data = response.json()
+        assert "detail" in data
+        assert len(data["detail"]) > 0
+
+    @pytest.mark.integration
+    def test_422_response_has_detail_message(self, integration_client, test_package):
+        """Test 422 responses include a detail message."""
+        project, package = test_package
+
+        # Upload with mismatched checksum
+        content = b"detail message test"
+        wrong_hash = "0" * 64
+
+        files = {"file": ("test.bin", io.BytesIO(content), "application/octet-stream")}
+        response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+            headers={"X-Checksum-SHA256": wrong_hash},
+        )
+        assert response.status_code == 422
+        data = response.json()
+        assert "detail" in data
+
+    @pytest.mark.integration
+    def test_error_response_is_json(self, integration_client, unique_test_id):
+        """Test error responses are valid JSON."""
+        response = integration_client.get(
+            f"/api/v1/project/nonexistent-{unique_test_id}/pkg/+/tag"
+        )
+        assert response.status_code == 404
+        # Should not raise exception - valid JSON
+        data = response.json()
+        assert isinstance(data, dict)

backend/tests/integration/test_integrity_verification.py

@@ -0,0 +1,768 @@
+"""
+Integration tests for artifact integrity verification.
+
+Tests cover:
+- Round-trip verification (upload -> download -> verify hash)
+- Consistency check endpoint
+- Header-based verification
+- Integrity verification across file sizes
+- Client-side verification workflow
+"""
+
+import pytest
+import io
+import hashlib
+from tests.factories import (
+    compute_sha256,
+    upload_test_file,
+    generate_content_with_hash,
+    s3_object_exists,
+    get_s3_client,
+    get_s3_bucket,
+)
+from tests.conftest import (
+    SIZE_1KB,
+    SIZE_10KB,
+    SIZE_100KB,
+    SIZE_1MB,
+    SIZE_10MB,
+)
+
+
+class TestRoundTripVerification:
+    """Tests for complete round-trip integrity verification."""
+
+    @pytest.mark.integration
+    def test_upload_download_hash_matches(self, integration_client, test_package):
+        """Test that upload -> download round trip preserves content integrity."""
+        project, package = test_package
+        content = b"Round trip integrity test content"
+        expected_hash = compute_sha256(content)
+
+        # Upload and capture returned hash
+        result = upload_test_file(
+            integration_client, project, package, content, tag="roundtrip"
+        )
+        uploaded_hash = result["artifact_id"]
+
+        # Verify upload returned correct hash
+        assert uploaded_hash == expected_hash
+
+        # Download artifact
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/roundtrip",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+
+        # Compute hash of downloaded content
+        downloaded_hash = compute_sha256(response.content)
+
+        # All three hashes should match
+        assert downloaded_hash == expected_hash
+        assert downloaded_hash == uploaded_hash
+
+    @pytest.mark.integration
+    def test_upload_response_contains_hash(self, integration_client, test_package):
+        """Test upload response contains artifact_id which is the SHA256 hash."""
+        project, package = test_package
+        content = b"Upload response hash test"
+        expected_hash = compute_sha256(content)
+
+        result = upload_test_file(integration_client, project, package, content)
+
+        assert "artifact_id" in result
+        assert result["artifact_id"] == expected_hash
+        assert len(result["artifact_id"]) == 64
+        assert all(c in "0123456789abcdef" for c in result["artifact_id"])
+
+    @pytest.mark.integration
+    def test_download_header_matches_artifact_id(self, integration_client, test_package):
+        """Test X-Checksum-SHA256 header matches artifact ID."""
+        project, package = test_package
+        content = b"Header verification test"
+        expected_hash = compute_sha256(content)
+
+        upload_test_file(
+            integration_client, project, package, content, tag="header-check"
+        )
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/header-check",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert response.headers.get("X-Checksum-SHA256") == expected_hash
+
+    @pytest.mark.integration
+    def test_etag_matches_artifact_id(self, integration_client, test_package):
+        """Test ETag header matches artifact ID."""
+        project, package = test_package
+        content = b"ETag verification test"
+        expected_hash = compute_sha256(content)
+
+        upload_test_file(
+            integration_client, project, package, content, tag="etag-check"
+        )
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/etag-check",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        etag = response.headers.get("ETag", "").strip('"')
+        assert etag == expected_hash
+
+    @pytest.mark.integration
+    def test_artifact_endpoint_returns_correct_hash(self, integration_client, test_package):
+        """Test artifact endpoint returns correct hash/ID."""
+        project, package = test_package
+        content = b"Artifact endpoint hash test"
+        expected_hash = compute_sha256(content)
+
+        upload_test_file(integration_client, project, package, content)
+
+        # Query artifact directly
+        response = integration_client.get(f"/api/v1/artifact/{expected_hash}")
+        assert response.status_code == 200
+        data = response.json()
+        assert data["id"] == expected_hash
+        assert data.get("sha256") == expected_hash
+
+
+class TestClientSideVerificationWorkflow:
+    """Tests for client-side verification workflow."""
+
+    @pytest.mark.integration
+    def test_client_can_verify_before_upload(self, integration_client, test_package):
+        """Test client can compute hash before upload and verify response matches."""
+        project, package = test_package
+        content = b"Client pre-upload verification test"
+
+        # Client computes hash locally before upload
+        client_hash = compute_sha256(content)
+
+        # Upload
+        result = upload_test_file(integration_client, project, package, content)
+
+        # Client verifies server returned the same hash
+        assert result["artifact_id"] == client_hash
+
+    @pytest.mark.integration
+    def test_client_can_provide_checksum_header(self, integration_client, test_package):
+        """Test client can provide X-Checksum-SHA256 header for verification."""
+        project, package = test_package
+        content = b"Client checksum header test"
+        client_hash = compute_sha256(content)
+
+        files = {"file": ("test.bin", io.BytesIO(content), "application/octet-stream")}
+        response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+            headers={"X-Checksum-SHA256": client_hash},
+        )
+        assert response.status_code == 200
+        assert response.json()["artifact_id"] == client_hash
+
+    @pytest.mark.integration
+    def test_checksum_mismatch_rejected(self, integration_client, test_package):
+        """Test upload with wrong client checksum is rejected."""
+        project, package = test_package
+        content = b"Checksum mismatch test"
+        wrong_hash = "0" * 64
+
+        files = {"file": ("test.bin", io.BytesIO(content), "application/octet-stream")}
+        response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+            headers={"X-Checksum-SHA256": wrong_hash},
+        )
+        assert response.status_code == 422
+
+    @pytest.mark.integration
+    def test_client_can_verify_after_download(self, integration_client, test_package):
+        """Test client can verify downloaded content matches header hash."""
+        project, package = test_package
+        content = b"Client post-download verification"
+
+        upload_test_file(
+            integration_client, project, package, content, tag="verify-after"
+        )
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/verify-after",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+
+        # Client gets hash from header
+        header_hash = response.headers.get("X-Checksum-SHA256")
+
+        # Client computes hash of downloaded content
+        downloaded_hash = compute_sha256(response.content)
+
+        # Client verifies they match
+        assert downloaded_hash == header_hash
+
+
+class TestIntegritySizeVariants:
+    """Tests for integrity verification across different file sizes."""
+
+    @pytest.mark.integration
+    def test_integrity_1kb(self, integration_client, test_package, sized_content):
+        """Test integrity verification for 1KB file."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_1KB, seed=100)
+
+        result = upload_test_file(
+            integration_client, project, package, content, tag="int-1kb"
+        )
+        assert result["artifact_id"] == expected_hash
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/int-1kb",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert compute_sha256(response.content) == expected_hash
+        assert response.headers.get("X-Checksum-SHA256") == expected_hash
+
+    @pytest.mark.integration
+    def test_integrity_100kb(self, integration_client, test_package, sized_content):
+        """Test integrity verification for 100KB file."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_100KB, seed=101)
+
+        result = upload_test_file(
+            integration_client, project, package, content, tag="int-100kb"
+        )
+        assert result["artifact_id"] == expected_hash
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/int-100kb",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert compute_sha256(response.content) == expected_hash
+        assert response.headers.get("X-Checksum-SHA256") == expected_hash
+
+    @pytest.mark.integration
+    def test_integrity_1mb(self, integration_client, test_package, sized_content):
+        """Test integrity verification for 1MB file."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_1MB, seed=102)
+
+        result = upload_test_file(
+            integration_client, project, package, content, tag="int-1mb"
+        )
+        assert result["artifact_id"] == expected_hash
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/int-1mb",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert compute_sha256(response.content) == expected_hash
+        assert response.headers.get("X-Checksum-SHA256") == expected_hash
+
+    @pytest.mark.integration
+    @pytest.mark.slow
+    def test_integrity_10mb(self, integration_client, test_package, sized_content):
+        """Test integrity verification for 10MB file."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_10MB, seed=103)
+
+        result = upload_test_file(
+            integration_client, project, package, content, tag="int-10mb"
+        )
+        assert result["artifact_id"] == expected_hash
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/int-10mb",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert compute_sha256(response.content) == expected_hash
+        assert response.headers.get("X-Checksum-SHA256") == expected_hash
+
+
+class TestConsistencyCheck:
+    """Tests for the admin consistency check endpoint."""
+
+    @pytest.mark.integration
+    def test_consistency_check_returns_200(self, integration_client):
+        """Test consistency check endpoint returns 200."""
+        response = integration_client.get("/api/v1/admin/consistency-check")
+        assert response.status_code == 200
+
+    @pytest.mark.integration
+    def test_consistency_check_response_format(self, integration_client):
+        """Test consistency check returns expected response format."""
+        response = integration_client.get("/api/v1/admin/consistency-check")
+        assert response.status_code == 200
+        data = response.json()
+
+        # Check expected fields
+        assert "total_artifacts_checked" in data
+        assert "orphaned_s3_objects" in data
+        assert "missing_s3_objects" in data
+        assert "size_mismatches" in data
+        assert "healthy" in data
+        assert "orphaned_s3_keys" in data
+        assert "missing_s3_keys" in data
+        assert "size_mismatch_artifacts" in data
+        # Verify types
+        assert isinstance(data["total_artifacts_checked"], int)
+        assert isinstance(data["orphaned_s3_objects"], int)
+        assert isinstance(data["missing_s3_objects"], int)
+        assert isinstance(data["size_mismatches"], int)
+        assert isinstance(data["healthy"], bool)
+        assert isinstance(data["orphaned_s3_keys"], list)
+        assert isinstance(data["missing_s3_keys"], list)
+        assert isinstance(data["size_mismatch_artifacts"], list)
+
+    @pytest.mark.integration
+    def test_consistency_check_after_upload(self, integration_client, test_package):
+        """Test consistency check passes after valid upload."""
+        project, package = test_package
+        content = b"Consistency check test content"
+
+        # Upload artifact
+        upload_test_file(integration_client, project, package, content)
+
+        # Run consistency check
+        response = integration_client.get("/api/v1/admin/consistency-check")
+        assert response.status_code == 200
+        data = response.json()
+
+        # Verify check ran and no issues
+        assert data["total_artifacts_checked"] >= 1
+        assert data["healthy"] is True
+
+    @pytest.mark.integration
+    def test_consistency_check_limit_parameter(self, integration_client):
+        """Test consistency check respects limit parameter."""
+        response = integration_client.get(
+            "/api/v1/admin/consistency-check",
+            params={"limit": 10}
+        )
+        assert response.status_code == 200
+        data = response.json()
+
+        # Lists should not exceed limit
+        assert len(data["orphaned_s3_keys"]) <= 10
+        assert len(data["missing_s3_keys"]) <= 10
+        assert len(data["size_mismatch_artifacts"]) <= 10
+
+
+class TestDigestHeader:
+    """Tests for RFC 3230 Digest header."""
+
+    @pytest.mark.integration
+    def test_download_includes_digest_header(self, integration_client, test_package):
+        """Test download includes Digest header in RFC 3230 format."""
+        project, package = test_package
+        content = b"Digest header test"
+        expected_hash = compute_sha256(content)
+
+        upload_test_file(
+            integration_client, project, package, content, tag="digest-test"
+        )
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/digest-test",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert "Digest" in response.headers
+
+        # Verify Digest format (sha-256=base64hash)
+        digest = response.headers["Digest"]
+        assert digest.startswith("sha-256=")
+
+    @pytest.mark.integration
+    def test_digest_header_base64_valid(self, integration_client, test_package):
+        """Test Digest header contains valid base64 encoding."""
+        import base64
+
+        project, package = test_package
+        content = b"Digest base64 test"
+        expected_hash = compute_sha256(content)
+
+        upload_test_file(
+            integration_client, project, package, content, tag="digest-b64"
+        )
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/digest-b64",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+
+        digest = response.headers["Digest"]
+        base64_part = digest.split("=", 1)[1]
+
+        # Should be valid base64
+        try:
+            decoded = base64.b64decode(base64_part)
+            assert len(decoded) == 32  # SHA256 is 32 bytes
+        except Exception as e:
+            pytest.fail(f"Invalid base64 in Digest header: {e}")
+
+
+class TestVerificationModes:
+    """Tests for download verification modes."""
+
+    @pytest.mark.integration
+    def test_pre_verification_mode(self, integration_client, test_package):
+        """Test pre-verification mode verifies before streaming."""
+        project, package = test_package
+        content = b"Pre-verification mode test"
+
+        upload_test_file(
+            integration_client, project, package, content, tag="pre-verify"
+        )
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/pre-verify",
+            params={"mode": "proxy", "verify": "true", "verify_mode": "pre"},
+        )
+        assert response.status_code == 200
+        assert response.content == content
+
+        # X-Verified header should be true
+        assert response.headers.get("X-Verified") == "true"
+
+    @pytest.mark.integration
+    def test_stream_verification_mode(self, integration_client, test_package):
+        """Test streaming verification mode."""
+        project, package = test_package
+        content = b"Stream verification mode test"
+
+        upload_test_file(
+            integration_client, project, package, content, tag="stream-verify"
+        )
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/stream-verify",
+            params={"mode": "proxy", "verify": "true", "verify_mode": "stream"},
+        )
+        assert response.status_code == 200
+        assert response.content == content
+
+
+class TestArtifactIntegrityEndpoint:
+    """Tests for artifact-specific integrity operations."""
+
+    @pytest.mark.integration
+    def test_artifact_size_matches(self, integration_client, test_package):
+        """Test artifact endpoint returns correct size."""
+        project, package = test_package
+        content = b"Artifact size test content"
+        expected_size = len(content)
+
+        result = upload_test_file(integration_client, project, package, content)
+        artifact_id = result["artifact_id"]
+
+        response = integration_client.get(f"/api/v1/artifact/{artifact_id}")
+        assert response.status_code == 200
+        data = response.json()
+        assert data["size"] == expected_size
+
+    @pytest.mark.integration
+    def test_content_length_header_matches_size(self, integration_client, test_package):
+        """Test Content-Length header matches artifact size."""
+        project, package = test_package
+        content = b"Content-Length header test"
+        expected_size = len(content)
+
+        upload_test_file(
+            integration_client, project, package, content, tag="content-len"
+        )
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/content-len",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert int(response.headers.get("Content-Length", 0)) == expected_size
+        assert len(response.content) == expected_size
+
+
+@pytest.mark.requires_direct_s3
+class TestCorruptionDetection:
+    """Tests for detecting corrupted S3 objects.
+
+    These tests directly manipulate S3 objects to simulate corruption
+    and verify that the system can detect hash mismatches.
+
+    Note: These tests require direct S3/MinIO access and are skipped in CI
+    where S3 is not directly accessible from the test runner.
+    """
+
+    @pytest.mark.integration
+    def test_detection_of_corrupted_content(self, integration_client, test_package):
+        """Test that corrupted S3 content is detected via hash mismatch.
+
+        Uploads content, then directly modifies the S3 object, then
+        verifies that the downloaded content hash doesn't match.
+        """
+        project, package = test_package
+        content = b"Original content for corruption test"
+        expected_hash = compute_sha256(content)
+
+        # Upload original content
+        result = upload_test_file(
+            integration_client, project, package, content, tag="corrupt-test"
+        )
+        assert result["artifact_id"] == expected_hash
+
+        # Get the S3 object and corrupt it
+        s3_client = get_s3_client()
+        bucket = get_s3_bucket()
+        s3_key = f"fruits/{expected_hash[:2]}/{expected_hash[2:4]}/{expected_hash}"
+
+        # Replace with corrupted content
+        corrupted_content = b"Corrupted content - different from original!"
+        s3_client.put_object(Bucket=bucket, Key=s3_key, Body=corrupted_content)
+
+        # Download via proxy (bypasses hash verification)
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/corrupt-test",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+
+        # Verify the downloaded content doesn't match original hash
+        downloaded_hash = compute_sha256(response.content)
+        assert downloaded_hash != expected_hash, "Corruption was not detected - hashes match"
+        assert response.content == corrupted_content
+
+        # The X-Checksum-SHA256 header should still show the original hash (from DB)
+        # but the actual content hash is different
+        header_hash = response.headers.get("X-Checksum-SHA256")
+        assert header_hash == expected_hash  # Header shows expected hash
+        assert downloaded_hash != header_hash  # But content is corrupted
+
+        # Restore original content for cleanup
+        s3_client.put_object(Bucket=bucket, Key=s3_key, Body=content)
+
+    @pytest.mark.integration
+    def test_detection_of_single_bit_flip(self, integration_client, test_package):
+        """Test detection of a single bit flip in S3 object content."""
+        project, package = test_package
+        content = b"Content for single bit flip detection test"
+        expected_hash = compute_sha256(content)
+
+        result = upload_test_file(
+            integration_client, project, package, content, tag="bitflip-test"
+        )
+        assert result["artifact_id"] == expected_hash
+
+        # Get S3 object and flip a single bit
+        s3_client = get_s3_client()
+        bucket = get_s3_bucket()
+        s3_key = f"fruits/{expected_hash[:2]}/{expected_hash[2:4]}/{expected_hash}"
+
+        # Flip the first bit of the first byte
+        corrupted_content = bytearray(content)
+        corrupted_content[0] ^= 0x01
+        corrupted_content = bytes(corrupted_content)
+
+        s3_client.put_object(Bucket=bucket, Key=s3_key, Body=corrupted_content)
+
+        # Download and verify hash mismatch
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/bitflip-test",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+
+        downloaded_hash = compute_sha256(response.content)
+        assert downloaded_hash != expected_hash, "Single bit flip not detected"
+
+        # Restore original
+        s3_client.put_object(Bucket=bucket, Key=s3_key, Body=content)
+
+    @pytest.mark.integration
+    def test_detection_of_truncated_content(self, integration_client, test_package):
+        """Test detection of truncated S3 object."""
+        project, package = test_package
+        content = b"This is content that will be truncated for testing purposes"
+        expected_hash = compute_sha256(content)
+
+        result = upload_test_file(
+            integration_client, project, package, content, tag="truncate-test"
+        )
+        assert result["artifact_id"] == expected_hash
+
+        # Get S3 object and truncate it
+        s3_client = get_s3_client()
+        bucket = get_s3_bucket()
+        s3_key = f"fruits/{expected_hash[:2]}/{expected_hash[2:4]}/{expected_hash}"
+
+        # Truncate to half the original size
+        truncated_content = content[: len(content) // 2]
+        s3_client.put_object(Bucket=bucket, Key=s3_key, Body=truncated_content)
+
+        # Download and verify hash mismatch
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/truncate-test",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+
+        downloaded_hash = compute_sha256(response.content)
+        assert downloaded_hash != expected_hash, "Truncation not detected"
+        assert len(response.content) < len(content), "Content was not truncated"
+
+        # Restore original
+        s3_client.put_object(Bucket=bucket, Key=s3_key, Body=content)
+
+    @pytest.mark.integration
+    def test_detection_of_appended_content(self, integration_client, test_package):
+        """Test detection of content with extra bytes appended."""
+        project, package = test_package
+        content = b"Original content"
+        expected_hash = compute_sha256(content)
+
+        result = upload_test_file(
+            integration_client, project, package, content, tag="append-test"
+        )
+        assert result["artifact_id"] == expected_hash
+
+        # Get S3 object and append extra bytes
+        s3_client = get_s3_client()
+        bucket = get_s3_bucket()
+        s3_key = f"fruits/{expected_hash[:2]}/{expected_hash[2:4]}/{expected_hash}"
+
+        appended_content = content + b" - extra bytes appended"
+        s3_client.put_object(Bucket=bucket, Key=s3_key, Body=appended_content)
+
+        # Download and verify hash mismatch
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/append-test",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+
+        downloaded_hash = compute_sha256(response.content)
+        assert downloaded_hash != expected_hash, "Appended content not detected"
+        assert len(response.content) > len(content), "Content was not extended"
+
+        # Restore original
+        s3_client.put_object(Bucket=bucket, Key=s3_key, Body=content)
+
+    @pytest.mark.integration
+    def test_client_detects_hash_mismatch_post_download(
+        self, integration_client, test_package
+    ):
+        """Test that a client can detect hash mismatch after downloading corrupted content.
+
+        This simulates the full client verification workflow:
+        1. Download content
+        2. Get expected hash from header
+        3. Compute actual hash of content
+        4. Verify they match (or detect corruption)
+        """
+        project, package = test_package
+        content = b"Content for client-side corruption detection"
+        expected_hash = compute_sha256(content)
+
+        result = upload_test_file(
+            integration_client, project, package, content, tag="client-detect"
+        )
+
+        # Corrupt the S3 object
+        s3_client = get_s3_client()
+        bucket = get_s3_bucket()
+        s3_key = f"fruits/{expected_hash[:2]}/{expected_hash[2:4]}/{expected_hash}"
+        corrupted = b"This is completely different content"
+        s3_client.put_object(Bucket=bucket, Key=s3_key, Body=corrupted)
+
+        # Simulate client download and verification
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/client-detect",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+
+        # Client gets expected hash from header
+        header_hash = response.headers.get("X-Checksum-SHA256")
+
+        # Client computes hash of downloaded content
+        actual_hash = compute_sha256(response.content)
+
+        # Client detects the mismatch
+        corruption_detected = actual_hash != header_hash
+        assert corruption_detected, "Client should detect hash mismatch"
+
+        # Restore original
+        s3_client.put_object(Bucket=bucket, Key=s3_key, Body=content)
+
+    @pytest.mark.integration
+    def test_consistency_check_detects_size_mismatch(
+        self, integration_client, test_package, unique_test_id
+    ):
+        """Test that consistency check detects size mismatches.
+
+        Uploads content, modifies S3 object size, then runs consistency check.
+        """
+        project, package = test_package
+        content = b"Content for size mismatch consistency check test " + unique_test_id.encode()
+        expected_hash = compute_sha256(content)
+
+        result = upload_test_file(
+            integration_client, project, package, content, tag="size-mismatch"
+        )
+
+        # Modify S3 object to have different size
+        s3_client = get_s3_client()
+        bucket = get_s3_bucket()
+        s3_key = f"fruits/{expected_hash[:2]}/{expected_hash[2:4]}/{expected_hash}"
+        different_size_content = content + b"extra extra extra"
+        s3_client.put_object(Bucket=bucket, Key=s3_key, Body=different_size_content)
+
+        # Run consistency check
+        response = integration_client.get("/api/v1/admin/consistency-check")
+        assert response.status_code == 200
+        data = response.json()
+
+        # Should detect the size mismatch
+        assert data["size_mismatches"] >= 1 or len(data["size_mismatch_artifacts"]) >= 1
+
+        # Restore original
+        s3_client.put_object(Bucket=bucket, Key=s3_key, Body=content)
+
+    @pytest.mark.integration
+    def test_consistency_check_detects_missing_s3_object(
+        self, integration_client, test_package, unique_test_id
+    ):
+        """Test that consistency check detects missing S3 objects.
+
+        Uploads content, deletes S3 object, then runs consistency check.
+        """
+        project, package = test_package
+        content = b"Content for missing S3 object test " + unique_test_id.encode()
+        expected_hash = compute_sha256(content)
+
+        result = upload_test_file(
+            integration_client, project, package, content, tag="missing-s3"
+        )
+
+        # Delete the S3 object
+        s3_client = get_s3_client()
+        bucket = get_s3_bucket()
+        s3_key = f"fruits/{expected_hash[:2]}/{expected_hash[2:4]}/{expected_hash}"
+        s3_client.delete_object(Bucket=bucket, Key=s3_key)
+
+        # Run consistency check
+        response = integration_client.get("/api/v1/admin/consistency-check")
+        assert response.status_code == 200
+        data = response.json()
+
+        # Should detect the missing S3 object
+        assert data["missing_s3_objects"] >= 1 or len(data["missing_s3_keys"]) >= 1
+
+        # Restore the object for cleanup
+        s3_client.put_object(Bucket=bucket, Key=s3_key, Body=content)

backend/tests/integration/test_large_uploads.py

@@ -0,0 +1,552 @@
+"""
+Integration tests for large file upload functionality.
+
+Tests cover:
+- Large file uploads (100MB, 1GB)
+- Multipart upload behavior
+- Upload metrics (duration, throughput)
+- Memory efficiency during uploads
+- Upload progress tracking
+
+Note: Large tests are marked with @pytest.mark.slow and will be skipped
+by default. Run with `pytest --run-slow` to include them.
+"""
+
+import os
+import pytest
+import io
+import time
+from tests.factories import (
+    compute_sha256,
+    upload_test_file,
+    s3_object_exists,
+)
+from tests.conftest import (
+    SIZE_1KB,
+    SIZE_100KB,
+    SIZE_1MB,
+    SIZE_10MB,
+    SIZE_100MB,
+    SIZE_1GB,
+)
+
+
+class TestUploadMetrics:
+    """Tests for upload duration and throughput metrics."""
+
+    @pytest.mark.integration
+    def test_upload_response_includes_duration_ms(self, integration_client, test_package):
+        """Test upload response includes duration_ms field."""
+        project, package = test_package
+        content = b"duration test content"
+
+        result = upload_test_file(
+            integration_client, project, package, content, tag="duration-test"
+        )
+
+        assert "duration_ms" in result
+        assert result["duration_ms"] is not None
+        assert result["duration_ms"] >= 0
+
+    @pytest.mark.integration
+    def test_upload_response_includes_throughput(self, integration_client, test_package):
+        """Test upload response includes throughput_mbps field."""
+        project, package = test_package
+        content = b"throughput test content"
+
+        result = upload_test_file(
+            integration_client, project, package, content, tag="throughput-test"
+        )
+
+        assert "throughput_mbps" in result
+        # For small files throughput may be very high or None
+        # Just verify the field exists
+
+    @pytest.mark.integration
+    def test_upload_duration_reasonable(
+        self, integration_client, test_package, sized_content
+    ):
+        """Test upload duration is reasonable for file size."""
+        project, package = test_package
+        content, _ = sized_content(SIZE_1MB, seed=100)
+
+        start = time.time()
+        result = upload_test_file(
+            integration_client, project, package, content, tag="duration-check"
+        )
+        actual_duration = (time.time() - start) * 1000  # ms
+
+        # Reported duration should be close to actual
+        assert result["duration_ms"] is not None
+        # Allow some variance (network overhead)
+        assert result["duration_ms"] <= actual_duration + 1000  # Within 1s
+
+
+class TestLargeFileUploads:
+    """Tests for large file uploads using multipart."""
+
+    @pytest.mark.integration
+    def test_upload_10mb_file(self, integration_client, test_package, sized_content):
+        """Test uploading a 10MB file."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_10MB, seed=200)
+
+        result = upload_test_file(
+            integration_client, project, package, content, tag="large-10mb"
+        )
+
+        assert result["artifact_id"] == expected_hash
+        assert result["size"] == SIZE_10MB
+        assert result["duration_ms"] is not None
+        assert result["throughput_mbps"] is not None
+
+    @pytest.mark.integration
+    @pytest.mark.slow
+    @pytest.mark.requires_direct_s3
+    def test_upload_100mb_file(self, integration_client, test_package, sized_content):
+        """Test uploading a 100MB file (triggers multipart upload)."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_100MB, seed=300)
+
+        result = upload_test_file(
+            integration_client, project, package, content, tag="large-100mb"
+        )
+
+        assert result["artifact_id"] == expected_hash
+        assert result["size"] == SIZE_100MB
+        # Verify S3 object exists
+        assert s3_object_exists(expected_hash)
+
+    @pytest.mark.integration
+    @pytest.mark.slow
+    @pytest.mark.large
+    def test_upload_1gb_file(self, integration_client, test_package, sized_content):
+        """Test uploading a 1GB file."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_1GB, seed=400)
+
+        result = upload_test_file(
+            integration_client, project, package, content, tag="large-1gb"
+        )
+
+        assert result["artifact_id"] == expected_hash
+        assert result["size"] == SIZE_1GB
+        # Should have measurable throughput
+        assert result["throughput_mbps"] is not None
+        assert result["throughput_mbps"] > 0
+
+    @pytest.mark.integration
+    def test_large_file_deduplication(
+        self, integration_client, test_package, sized_content, unique_test_id
+    ):
+        """Test deduplication works for large files."""
+        project, package = test_package
+        # Use unique_test_id to ensure unique content per test run
+        seed = hash(unique_test_id) % 10000
+        content, expected_hash = sized_content(SIZE_10MB, seed=seed)
+
+        # First upload
+        result1 = upload_test_file(
+            integration_client, project, package, content, tag=f"dedup-{unique_test_id}-1"
+        )
+        # Note: may be True if previous test uploaded same content
+        first_dedupe = result1["deduplicated"]
+
+        # Second upload of same content
+        result2 = upload_test_file(
+            integration_client, project, package, content, tag=f"dedup-{unique_test_id}-2"
+        )
+        assert result2["artifact_id"] == expected_hash
+        # Second upload MUST be deduplicated
+        assert result2["deduplicated"] is True
+
+
+class TestUploadProgress:
+    """Tests for upload progress tracking endpoint."""
+
+    @pytest.mark.integration
+    def test_progress_endpoint_returns_not_found_for_invalid_id(
+        self, integration_client, test_package
+    ):
+        """Test progress endpoint returns not_found status for invalid upload ID."""
+        project, package = test_package
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/upload/invalid-upload-id/progress"
+        )
+
+        assert response.status_code == 200
+        data = response.json()
+        assert data["status"] == "not_found"
+        assert data["upload_id"] == "invalid-upload-id"
+
+    @pytest.mark.integration
+    def test_progress_endpoint_requires_valid_project(
+        self, integration_client, unique_test_id
+    ):
+        """Test progress endpoint validates project exists."""
+        response = integration_client.get(
+            f"/api/v1/project/nonexistent-{unique_test_id}/pkg/upload/upload-id/progress"
+        )
+
+        assert response.status_code == 404
+
+    @pytest.mark.integration
+    def test_progress_endpoint_requires_valid_package(
+        self, integration_client, test_project, unique_test_id
+    ):
+        """Test progress endpoint validates package exists."""
+        response = integration_client.get(
+            f"/api/v1/project/{test_project}/nonexistent-{unique_test_id}/upload/upload-id/progress"
+        )
+
+        assert response.status_code == 404
+
+
+class TestResumableUploadProgress:
+    """Tests for progress tracking during resumable uploads."""
+
+    @pytest.mark.integration
+    def test_resumable_upload_init_and_progress(
+        self, integration_client, test_package, sized_content
+    ):
+        """Test initializing resumable upload and checking progress."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_100KB, seed=600)
+
+        # Get API key for auth
+        api_key_response = integration_client.post(
+            "/api/v1/auth/keys",
+            json={"name": "progress-test-key"},
+        )
+        assert api_key_response.status_code == 200
+        api_key = api_key_response.json()["key"]
+
+        # Initialize resumable upload
+        init_response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload/init",
+            json={
+                "expected_hash": expected_hash,
+                "filename": "progress-test.bin",
+                "size": SIZE_100KB,
+            },
+            headers={"Authorization": f"Bearer {api_key}"},
+        )
+        assert init_response.status_code == 200
+        upload_id = init_response.json().get("upload_id")
+
+        if upload_id:
+            # Check initial progress
+            progress_response = integration_client.get(
+                f"/api/v1/project/{project}/{package}/upload/{upload_id}/progress",
+                headers={"Authorization": f"Bearer {api_key}"},
+            )
+            assert progress_response.status_code == 200
+            progress = progress_response.json()
+            assert progress["status"] == "in_progress"
+            assert progress["bytes_uploaded"] == 0
+            assert progress["bytes_total"] == SIZE_100KB
+
+            # Abort to clean up
+            integration_client.delete(
+                f"/api/v1/project/{project}/{package}/upload/{upload_id}",
+                headers={"Authorization": f"Bearer {api_key}"},
+            )
+
+
+class TestUploadSizeLimits:
+    """Tests for upload size limit enforcement."""
+
+    @pytest.mark.integration
+    def test_empty_file_rejected(self, integration_client, test_package):
+        """Test empty files are rejected."""
+        project, package = test_package
+
+        files = {"file": ("empty.txt", io.BytesIO(b""), "application/octet-stream")}
+        response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+        )
+
+        assert response.status_code in [400, 422]
+
+    @pytest.mark.integration
+    def test_minimum_size_accepted(self, integration_client, test_package):
+        """Test 1-byte file is accepted."""
+        project, package = test_package
+        content = b"X"
+
+        result = upload_test_file(
+            integration_client, project, package, content, tag="min-size"
+        )
+
+        assert result["size"] == 1
+
+    @pytest.mark.integration
+    def test_content_length_header_used_in_response(self, integration_client, test_package):
+        """Test that upload response size matches Content-Length."""
+        project, package = test_package
+        content = b"content length verification test"
+
+        result = upload_test_file(
+            integration_client, project, package, content, tag="content-length-test"
+        )
+
+        # Size in response should match actual content length
+        assert result["size"] == len(content)
+
+
+class TestUploadErrorHandling:
+    """Tests for upload error handling."""
+
+    @pytest.mark.integration
+    def test_upload_to_nonexistent_project_returns_404(
+        self, integration_client, unique_test_id
+    ):
+        """Test upload to nonexistent project returns 404."""
+        content = b"test content"
+        files = {"file": ("test.bin", io.BytesIO(content), "application/octet-stream")}
+
+        response = integration_client.post(
+            f"/api/v1/project/nonexistent-{unique_test_id}/pkg/upload",
+            files=files,
+        )
+
+        assert response.status_code == 404
+
+    @pytest.mark.integration
+    def test_upload_to_nonexistent_package_returns_404(
+        self, integration_client, test_project, unique_test_id
+    ):
+        """Test upload to nonexistent package returns 404."""
+        content = b"test content"
+        files = {"file": ("test.bin", io.BytesIO(content), "application/octet-stream")}
+
+        response = integration_client.post(
+            f"/api/v1/project/{test_project}/nonexistent-{unique_test_id}/upload",
+            files=files,
+        )
+
+        assert response.status_code == 404
+
+    @pytest.mark.integration
+    def test_upload_without_file_returns_422(self, integration_client, test_package):
+        """Test upload without file field returns 422."""
+        project, package = test_package
+
+        response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            data={"tag": "no-file"},
+        )
+
+        assert response.status_code == 422
+
+    @pytest.mark.integration
+    def test_upload_with_invalid_checksum_rejected(
+        self, integration_client, test_package
+    ):
+        """Test upload with invalid checksum header format is rejected."""
+        project, package = test_package
+        content = b"checksum test"
+
+        files = {"file": ("test.bin", io.BytesIO(content), "application/octet-stream")}
+        response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+            headers={"X-Checksum-SHA256": "invalid-checksum"},
+        )
+
+        assert response.status_code == 400
+
+    @pytest.mark.integration
+    def test_upload_with_mismatched_checksum_rejected(
+        self, integration_client, test_package
+    ):
+        """Test upload with wrong checksum is rejected."""
+        project, package = test_package
+        content = b"mismatch test"
+        wrong_hash = "0" * 64
+
+        files = {"file": ("test.bin", io.BytesIO(content), "application/octet-stream")}
+        response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+            headers={"X-Checksum-SHA256": wrong_hash},
+        )
+
+        assert response.status_code == 422
+        assert "verification failed" in response.json().get("detail", "").lower()
+
+
+class TestResumableUploadCancellation:
+    """Tests for resumable upload cancellation."""
+
+    @pytest.mark.integration
+    def test_abort_resumable_upload(self, integration_client, test_package, sized_content):
+        """Test aborting a resumable upload cleans up properly."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_100KB, seed=700)
+
+        # Get API key for auth
+        api_key_response = integration_client.post(
+            "/api/v1/auth/keys",
+            json={"name": "abort-test-key"},
+        )
+        assert api_key_response.status_code == 200
+        api_key = api_key_response.json()["key"]
+
+        # Initialize resumable upload
+        init_response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload/init",
+            json={
+                "expected_hash": expected_hash,
+                "filename": "abort-test.bin",
+                "size": SIZE_100KB,
+            },
+            headers={"Authorization": f"Bearer {api_key}"},
+        )
+        assert init_response.status_code == 200
+        upload_id = init_response.json().get("upload_id")
+
+        if upload_id:
+            # Abort the upload (without uploading any parts)
+            abort_response = integration_client.delete(
+                f"/api/v1/project/{project}/{package}/upload/{upload_id}",
+                headers={"Authorization": f"Bearer {api_key}"},
+            )
+            assert abort_response.status_code in [200, 204]
+
+            # Verify progress shows not_found after abort
+            progress_response = integration_client.get(
+                f"/api/v1/project/{project}/{package}/upload/{upload_id}/progress",
+                headers={"Authorization": f"Bearer {api_key}"},
+            )
+            assert progress_response.status_code == 200
+            assert progress_response.json()["status"] == "not_found"
+
+    @pytest.mark.integration
+    def test_abort_nonexistent_upload(self, integration_client, test_package):
+        """Test aborting nonexistent upload returns appropriate error."""
+        project, package = test_package
+
+        # Get API key for auth
+        api_key_response = integration_client.post(
+            "/api/v1/auth/keys",
+            json={"name": "abort-nonexistent-key"},
+        )
+        assert api_key_response.status_code == 200
+        api_key = api_key_response.json()["key"]
+
+        response = integration_client.delete(
+            f"/api/v1/project/{project}/{package}/upload/nonexistent-upload-id",
+            headers={"Authorization": f"Bearer {api_key}"},
+        )
+
+        # Should return 404 or 200 (idempotent delete)
+        assert response.status_code in [200, 204, 404]
+
+
+class TestUploadTimeout:
+    """Tests for upload timeout handling."""
+
+    @pytest.mark.integration
+    def test_upload_with_short_timeout_succeeds_for_small_file(
+        self, integration_client, test_package
+    ):
+        """Test small file upload succeeds with reasonable timeout."""
+        project, package = test_package
+        content = b"small timeout test"
+
+        # httpx client should handle this quickly
+        result = upload_test_file(
+            integration_client, project, package, content, tag="timeout-small"
+        )
+
+        assert result["artifact_id"] is not None
+
+    @pytest.mark.integration
+    def test_upload_response_duration_under_timeout(
+        self, integration_client, test_package, sized_content
+    ):
+        """Test upload completes within reasonable time."""
+        project, package = test_package
+        content, _ = sized_content(SIZE_1MB, seed=800)
+
+        start = time.time()
+        result = upload_test_file(
+            integration_client, project, package, content, tag="timeout-check"
+        )
+        duration = time.time() - start
+
+        # 1MB should upload in well under 60 seconds on local
+        assert duration < 60
+        assert result["artifact_id"] is not None
+
+
+class TestConcurrentUploads:
+    """Tests for concurrent upload handling."""
+
+    @pytest.mark.integration
+    def test_concurrent_different_files(
+        self, integration_client, test_package, sized_content
+    ):
+        """Test concurrent uploads of different files succeed."""
+        from concurrent.futures import ThreadPoolExecutor, as_completed
+
+        project, package = test_package
+
+        # Get API key for auth
+        api_key_response = integration_client.post(
+            "/api/v1/auth/keys",
+            json={"name": "concurrent-diff-key"},
+        )
+        assert api_key_response.status_code == 200
+        api_key = api_key_response.json()["key"]
+
+        num_uploads = 3
+        results = []
+        errors = []
+
+        def upload_unique_file(idx):
+            try:
+                from httpx import Client
+
+                content, expected_hash = sized_content(SIZE_100KB, seed=900 + idx)
+
+                base_url = os.environ.get("ORCHARD_TEST_URL", "http://localhost:8080")
+                with Client(base_url=base_url, timeout=30.0) as client:
+                    files = {
+                        "file": (
+                            f"concurrent-{idx}.bin",
+                            io.BytesIO(content),
+                            "application/octet-stream",
+                        )
+                    }
+                    response = client.post(
+                        f"/api/v1/project/{project}/{package}/upload",
+                        files=files,
+                        data={"tag": f"concurrent-diff-{idx}"},
+                        headers={"Authorization": f"Bearer {api_key}"},
+                    )
+                    if response.status_code == 200:
+                        results.append((idx, response.json(), expected_hash))
+                    else:
+                        errors.append(f"Upload {idx}: {response.status_code} - {response.text}")
+            except Exception as e:
+                errors.append(f"Upload {idx}: {str(e)}")
+
+        with ThreadPoolExecutor(max_workers=num_uploads) as executor:
+            futures = [executor.submit(upload_unique_file, i) for i in range(num_uploads)]
+            for future in as_completed(futures):
+                pass
+
+        assert len(errors) == 0, f"Concurrent upload errors: {errors}"
+        assert len(results) == num_uploads
+
+        # Each upload should have unique artifact ID
+        artifact_ids = set(r[1]["artifact_id"] for r in results)
+        assert len(artifact_ids) == num_uploads
+
+        # Each should match expected hash
+        for idx, result, expected_hash in results:
+            assert result["artifact_id"] == expected_hash

backend/tests/integration/test_size_boundary.py

@@ -0,0 +1,583 @@
+"""
+Integration tests for upload/download with various file sizes.
+
+Tests cover:
+- Small files (0B - 100KB)
+- Medium files (1MB - 50MB)
+- Large files (100MB - 1GB) - marked as slow/large
+- Exact chunk boundaries
+- Data integrity verification across all sizes
+"""
+
+import pytest
+import io
+import time
+from concurrent.futures import ThreadPoolExecutor, as_completed
+from tests.factories import (
+    compute_sha256,
+    upload_test_file,
+    generate_content,
+    generate_content_with_hash,
+)
+from tests.conftest import (
+    SIZE_1B,
+    SIZE_1KB,
+    SIZE_10KB,
+    SIZE_100KB,
+    SIZE_1MB,
+    SIZE_5MB,
+    SIZE_10MB,
+    SIZE_50MB,
+    SIZE_100MB,
+    SIZE_250MB,
+    SIZE_500MB,
+    SIZE_1GB,
+    CHUNK_SIZE,
+    MULTIPART_THRESHOLD,
+)
+
+
+class TestSmallFileSizes:
+    """Tests for small file uploads/downloads (0B - 100KB)."""
+
+    @pytest.mark.integration
+    def test_upload_download_1_byte(self, integration_client, test_package, sized_content):
+        """Test upload/download of 1 byte file."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_1B, seed=1)
+
+        result = upload_test_file(
+            integration_client, project, package, content,
+            filename="1byte.bin", tag="1byte"
+        )
+        assert result["artifact_id"] == expected_hash
+        assert result["size"] == SIZE_1B
+
+        # Download and verify
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/1byte",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert response.content == content
+        assert len(response.content) == SIZE_1B
+
+    @pytest.mark.integration
+    def test_upload_download_1kb(self, integration_client, test_package, sized_content):
+        """Test upload/download of 1KB file."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_1KB, seed=2)
+
+        result = upload_test_file(
+            integration_client, project, package, content,
+            filename="1kb.bin", tag="1kb"
+        )
+        assert result["artifact_id"] == expected_hash
+        assert result["size"] == SIZE_1KB
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/1kb",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert response.content == content
+
+    @pytest.mark.integration
+    def test_upload_download_10kb(self, integration_client, test_package, sized_content):
+        """Test upload/download of 10KB file."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_10KB, seed=3)
+
+        result = upload_test_file(
+            integration_client, project, package, content,
+            filename="10kb.bin", tag="10kb"
+        )
+        assert result["artifact_id"] == expected_hash
+        assert result["size"] == SIZE_10KB
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/10kb",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert response.content == content
+
+    @pytest.mark.integration
+    def test_upload_download_100kb(self, integration_client, test_package, sized_content):
+        """Test upload/download of 100KB file."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_100KB, seed=4)
+
+        result = upload_test_file(
+            integration_client, project, package, content,
+            filename="100kb.bin", tag="100kb"
+        )
+        assert result["artifact_id"] == expected_hash
+        assert result["size"] == SIZE_100KB
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/100kb",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert response.content == content
+
+
+class TestMediumFileSizes:
+    """Tests for medium file uploads/downloads (1MB - 50MB)."""
+
+    @pytest.mark.integration
+    def test_upload_download_1mb(self, integration_client, test_package, sized_content):
+        """Test upload/download of 1MB file."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_1MB, seed=10)
+
+        result = upload_test_file(
+            integration_client, project, package, content,
+            filename="1mb.bin", tag="1mb"
+        )
+        assert result["artifact_id"] == expected_hash
+        assert result["size"] == SIZE_1MB
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/1mb",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert len(response.content) == SIZE_1MB
+        assert compute_sha256(response.content) == expected_hash
+
+    @pytest.mark.integration
+    def test_upload_download_5mb(self, integration_client, test_package, sized_content):
+        """Test upload/download of 5MB file (multipart threshold boundary area)."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_5MB, seed=11)
+
+        result = upload_test_file(
+            integration_client, project, package, content,
+            filename="5mb.bin", tag="5mb"
+        )
+        assert result["artifact_id"] == expected_hash
+        assert result["size"] == SIZE_5MB
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/5mb",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert len(response.content) == SIZE_5MB
+        assert compute_sha256(response.content) == expected_hash
+
+    @pytest.mark.integration
+    @pytest.mark.slow
+    def test_upload_download_10mb(self, integration_client, test_package, sized_content):
+        """Test upload/download of 10MB file."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_10MB, seed=12)
+
+        result = upload_test_file(
+            integration_client, project, package, content,
+            filename="10mb.bin", tag="10mb"
+        )
+        assert result["artifact_id"] == expected_hash
+        assert result["size"] == SIZE_10MB
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/10mb",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert len(response.content) == SIZE_10MB
+        assert compute_sha256(response.content) == expected_hash
+
+    @pytest.mark.integration
+    @pytest.mark.slow
+    def test_upload_download_50mb(self, integration_client, test_package, sized_content):
+        """Test upload/download of 50MB file."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_50MB, seed=13)
+
+        start_time = time.time()
+        result = upload_test_file(
+            integration_client, project, package, content,
+            filename="50mb.bin", tag="50mb"
+        )
+        upload_time = time.time() - start_time
+
+        assert result["artifact_id"] == expected_hash
+        assert result["size"] == SIZE_50MB
+
+        start_time = time.time()
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/50mb",
+            params={"mode": "proxy"},
+        )
+        download_time = time.time() - start_time
+
+        assert response.status_code == 200
+        assert len(response.content) == SIZE_50MB
+        assert compute_sha256(response.content) == expected_hash
+
+        # Log timing for performance tracking
+        print(f"\n50MB upload: {upload_time:.2f}s, download: {download_time:.2f}s")
+
+
+class TestLargeFileSizes:
+    """Tests for large file uploads/downloads (100MB - 1GB).
+
+    These tests are marked as slow and large, skipped by default.
+    Run with: pytest -m "large" to include these tests.
+    """
+
+    @pytest.mark.integration
+    @pytest.mark.slow
+    @pytest.mark.large
+    def test_upload_download_100mb(self, integration_client, test_package, sized_content):
+        """Test upload/download of 100MB file (multipart threshold)."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_100MB, seed=100)
+
+        start_time = time.time()
+        result = upload_test_file(
+            integration_client, project, package, content,
+            filename="100mb.bin", tag="100mb"
+        )
+        upload_time = time.time() - start_time
+
+        assert result["artifact_id"] == expected_hash
+        assert result["size"] == SIZE_100MB
+
+        start_time = time.time()
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/100mb",
+            params={"mode": "proxy"},
+        )
+        download_time = time.time() - start_time
+
+        assert response.status_code == 200
+        assert len(response.content) == SIZE_100MB
+        assert compute_sha256(response.content) == expected_hash
+
+        print(f"\n100MB upload: {upload_time:.2f}s, download: {download_time:.2f}s")
+
+    @pytest.mark.integration
+    @pytest.mark.slow
+    @pytest.mark.large
+    def test_upload_download_250mb(self, integration_client, test_package, sized_content):
+        """Test upload/download of 250MB file."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_250MB, seed=250)
+
+        start_time = time.time()
+        result = upload_test_file(
+            integration_client, project, package, content,
+            filename="250mb.bin", tag="250mb"
+        )
+        upload_time = time.time() - start_time
+
+        assert result["artifact_id"] == expected_hash
+        assert result["size"] == SIZE_250MB
+
+        start_time = time.time()
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/250mb",
+            params={"mode": "proxy"},
+        )
+        download_time = time.time() - start_time
+
+        assert response.status_code == 200
+        assert len(response.content) == SIZE_250MB
+        assert compute_sha256(response.content) == expected_hash
+
+        print(f"\n250MB upload: {upload_time:.2f}s, download: {download_time:.2f}s")
+
+    @pytest.mark.integration
+    @pytest.mark.slow
+    @pytest.mark.large
+    def test_upload_download_500mb(self, integration_client, test_package, sized_content):
+        """Test upload/download of 500MB file."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_500MB, seed=500)
+
+        start_time = time.time()
+        result = upload_test_file(
+            integration_client, project, package, content,
+            filename="500mb.bin", tag="500mb"
+        )
+        upload_time = time.time() - start_time
+
+        assert result["artifact_id"] == expected_hash
+        assert result["size"] == SIZE_500MB
+
+        start_time = time.time()
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/500mb",
+            params={"mode": "proxy"},
+        )
+        download_time = time.time() - start_time
+
+        assert response.status_code == 200
+        assert len(response.content) == SIZE_500MB
+        assert compute_sha256(response.content) == expected_hash
+
+        print(f"\n500MB upload: {upload_time:.2f}s, download: {download_time:.2f}s")
+
+    @pytest.mark.integration
+    @pytest.mark.slow
+    @pytest.mark.large
+    def test_upload_download_1gb(self, integration_client, test_package, sized_content):
+        """Test upload/download of 1GB file.
+
+        This test may take several minutes depending on network/disk speed.
+        """
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_1GB, seed=1024)
+
+        start_time = time.time()
+        result = upload_test_file(
+            integration_client, project, package, content,
+            filename="1gb.bin", tag="1gb"
+        )
+        upload_time = time.time() - start_time
+
+        assert result["artifact_id"] == expected_hash
+        assert result["size"] == SIZE_1GB
+
+        start_time = time.time()
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/1gb",
+            params={"mode": "proxy"},
+        )
+        download_time = time.time() - start_time
+
+        assert response.status_code == 200
+        assert len(response.content) == SIZE_1GB
+        assert compute_sha256(response.content) == expected_hash
+
+        print(f"\n1GB upload: {upload_time:.2f}s, download: {download_time:.2f}s")
+
+
+class TestChunkBoundaries:
+    """Tests for exact chunk size boundaries."""
+
+    @pytest.mark.integration
+    def test_upload_download_at_chunk_size(self, integration_client, test_package, sized_content):
+        """Test upload/download at exact chunk size (64KB)."""
+        project, package = test_package
+        content, expected_hash = sized_content(CHUNK_SIZE, seed=64)
+
+        result = upload_test_file(
+            integration_client, project, package, content,
+            filename="chunk.bin", tag="chunk-exact"
+        )
+        assert result["artifact_id"] == expected_hash
+        assert result["size"] == CHUNK_SIZE
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/chunk-exact",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert response.content == content
+
+    @pytest.mark.integration
+    def test_upload_download_chunk_size_plus_1(self, integration_client, test_package, sized_content):
+        """Test upload/download at chunk size + 1 byte."""
+        project, package = test_package
+        size = CHUNK_SIZE + 1
+        content, expected_hash = sized_content(size, seed=65)
+
+        result = upload_test_file(
+            integration_client, project, package, content,
+            filename="chunk_plus.bin", tag="chunk-plus"
+        )
+        assert result["artifact_id"] == expected_hash
+        assert result["size"] == size
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/chunk-plus",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert response.content == content
+
+    @pytest.mark.integration
+    def test_upload_download_chunk_size_minus_1(self, integration_client, test_package, sized_content):
+        """Test upload/download at chunk size - 1 byte."""
+        project, package = test_package
+        size = CHUNK_SIZE - 1
+        content, expected_hash = sized_content(size, seed=63)
+
+        result = upload_test_file(
+            integration_client, project, package, content,
+            filename="chunk_minus.bin", tag="chunk-minus"
+        )
+        assert result["artifact_id"] == expected_hash
+        assert result["size"] == size
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/chunk-minus",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert response.content == content
+
+    @pytest.mark.integration
+    def test_upload_download_multiple_chunks(self, integration_client, test_package, sized_content):
+        """Test upload/download spanning multiple chunks."""
+        project, package = test_package
+        size = CHUNK_SIZE * 3 + 1000  # 3 full chunks + partial
+        content, expected_hash = sized_content(size, seed=300)
+
+        result = upload_test_file(
+            integration_client, project, package, content,
+            filename="multi_chunk.bin", tag="multi-chunk"
+        )
+        assert result["artifact_id"] == expected_hash
+        assert result["size"] == size
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/multi-chunk",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert response.content == content
+
+
+class TestDataIntegrity:
+    """Tests for data integrity with various content types."""
+
+    @pytest.mark.integration
+    def test_binary_content_integrity(self, integration_client, test_package):
+        """Test binary content (all byte values 0-255) integrity."""
+        project, package = test_package
+        # Content with all 256 possible byte values
+        content = bytes(range(256)) * 100  # 25.6KB
+        expected_hash = compute_sha256(content)
+
+        result = upload_test_file(
+            integration_client, project, package, content,
+            filename="binary.bin", tag="binary"
+        )
+        assert result["artifact_id"] == expected_hash
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/binary",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert response.content == content
+
+    @pytest.mark.integration
+    def test_text_content_integrity(self, integration_client, test_package):
+        """Test UTF-8 text content integrity."""
+        project, package = test_package
+        content = "Hello, World! 你好世界 🌍 مرحبا العالم".encode("utf-8")
+        expected_hash = compute_sha256(content)
+
+        result = upload_test_file(
+            integration_client, project, package, content,
+            filename="text.txt", tag="text"
+        )
+        assert result["artifact_id"] == expected_hash
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/text",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert response.content == content
+        assert response.content.decode("utf-8") == "Hello, World! 你好世界 🌍 مرحبا العالم"
+
+    @pytest.mark.integration
+    def test_null_bytes_content_integrity(self, integration_client, test_package):
+        """Test content with null bytes."""
+        project, package = test_package
+        content = b"before\x00null\x00bytes\x00after"
+        expected_hash = compute_sha256(content)
+
+        result = upload_test_file(
+            integration_client, project, package, content,
+            filename="nulls.bin", tag="nulls"
+        )
+        assert result["artifact_id"] == expected_hash
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/nulls",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert response.content == content
+        assert b"\x00" in response.content
+
+    @pytest.mark.integration
+    def test_unicode_filename_integrity(self, integration_client, test_package):
+        """Test file with unicode filename."""
+        project, package = test_package
+        content = b"unicode filename test"
+        expected_hash = compute_sha256(content)
+
+        result = upload_test_file(
+            integration_client, project, package, content,
+            filename="文件名.txt", tag="unicode-name"
+        )
+        assert result["artifact_id"] == expected_hash
+        assert result["original_name"] == "文件名.txt"
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/unicode-name",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert response.content == content
+
+    @pytest.mark.integration
+    def test_compressed_content_integrity(self, integration_client, test_package):
+        """Test gzip-compressed content integrity."""
+        import gzip
+
+        project, package = test_package
+        original = b"This is some text that will be compressed " * 100
+        content = gzip.compress(original)
+        expected_hash = compute_sha256(content)
+
+        result = upload_test_file(
+            integration_client, project, package, content,
+            filename="data.gz", tag="compressed"
+        )
+        assert result["artifact_id"] == expected_hash
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/compressed",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert response.content == content
+        # Verify we can decompress
+        assert gzip.decompress(response.content) == original
+
+    @pytest.mark.integration
+    def test_hash_verification_matches(self, integration_client, test_package, sized_content):
+        """Test that computed hash matches artifact_id for various sizes."""
+        project, package = test_package
+
+        sizes = [SIZE_1B, SIZE_1KB, SIZE_10KB, SIZE_100KB, SIZE_1MB]
+
+        for i, size in enumerate(sizes):
+            content, expected_hash = sized_content(size, seed=1000 + i)
+
+            result = upload_test_file(
+                integration_client, project, package, content,
+                filename=f"hash_test_{size}.bin", tag=f"hash-{size}"
+            )
+
+            # Verify artifact_id matches expected hash
+            assert result["artifact_id"] == expected_hash
+
+            # Download and verify hash of downloaded content
+            response = integration_client.get(
+                f"/api/v1/project/{project}/{package}/+/hash-{size}",
+                params={"mode": "proxy"},
+            )
+            downloaded_hash = compute_sha256(response.content)
+            assert downloaded_hash == expected_hash

backend/tests/integration/test_streaming_download.py

@@ -0,0 +1,535 @@
+"""
+Integration tests for streaming download functionality.
+
+Tests cover:
+- HTTP Range requests (partial downloads, resume)
+- Conditional requests (If-None-Match, If-Modified-Since)
+- Caching headers (Cache-Control, Last-Modified, Accept-Ranges)
+- Large file streaming
+- Download modes (proxy, redirect, presigned)
+"""
+
+import pytest
+import io
+import time
+from email.utils import formatdate
+from tests.factories import (
+    compute_sha256,
+    upload_test_file,
+)
+from tests.conftest import (
+    SIZE_1KB,
+    SIZE_100KB,
+    SIZE_1MB,
+)
+
+
+class TestRangeRequests:
+    """Tests for HTTP Range request support (partial downloads)."""
+
+    @pytest.mark.integration
+    def test_range_request_first_bytes(self, integration_client, test_package):
+        """Test range request for first N bytes."""
+        project, package = test_package
+        content = b"0123456789" * 100  # 1000 bytes
+        upload_test_file(integration_client, project, package, content, tag="range-test")
+
+        # Request first 10 bytes
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/range-test",
+            params={"mode": "proxy"},
+            headers={"Range": "bytes=0-9"},
+        )
+        assert response.status_code == 206  # Partial Content
+        assert response.content == b"0123456789"
+        assert "Content-Range" in response.headers
+        assert response.headers["Content-Range"].startswith("bytes 0-9/")
+
+    @pytest.mark.integration
+    def test_range_request_middle_bytes(self, integration_client, test_package):
+        """Test range request for bytes in the middle."""
+        project, package = test_package
+        content = b"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
+        upload_test_file(integration_client, project, package, content, tag="range-mid")
+
+        # Request bytes 10-19 (KLMNOPQRST)
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/range-mid",
+            params={"mode": "proxy"},
+            headers={"Range": "bytes=10-19"},
+        )
+        assert response.status_code == 206
+        assert response.content == b"KLMNOPQRST"
+
+    @pytest.mark.integration
+    def test_range_request_suffix_bytes(self, integration_client, test_package):
+        """Test range request for last N bytes (suffix range)."""
+        project, package = test_package
+        content = b"0123456789ABCDEF"  # 16 bytes
+        upload_test_file(integration_client, project, package, content, tag="range-suffix")
+
+        # Request last 4 bytes
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/range-suffix",
+            params={"mode": "proxy"},
+            headers={"Range": "bytes=-4"},
+        )
+        assert response.status_code == 206
+        assert response.content == b"CDEF"
+
+    @pytest.mark.integration
+    def test_range_request_open_ended(self, integration_client, test_package):
+        """Test range request from offset to end."""
+        project, package = test_package
+        content = b"0123456789"
+        upload_test_file(integration_client, project, package, content, tag="range-open")
+
+        # Request from byte 5 to end
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/range-open",
+            params={"mode": "proxy"},
+            headers={"Range": "bytes=5-"},
+        )
+        assert response.status_code == 206
+        assert response.content == b"56789"
+
+    @pytest.mark.integration
+    def test_range_request_includes_accept_ranges_header(
+        self, integration_client, test_package
+    ):
+        """Test that range requests include Accept-Ranges header."""
+        project, package = test_package
+        content = b"test content"
+        upload_test_file(integration_client, project, package, content, tag="accept-ranges")
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/accept-ranges",
+            params={"mode": "proxy"},
+            headers={"Range": "bytes=0-4"},
+        )
+        assert response.status_code == 206
+        assert response.headers.get("Accept-Ranges") == "bytes"
+
+    @pytest.mark.integration
+    def test_full_download_advertises_accept_ranges(
+        self, integration_client, test_package
+    ):
+        """Test that full downloads advertise range support."""
+        project, package = test_package
+        content = b"test content"
+        upload_test_file(integration_client, project, package, content, tag="full-accept")
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/full-accept",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert response.headers.get("Accept-Ranges") == "bytes"
+
+
+class TestConditionalRequests:
+    """Tests for conditional request handling (304 Not Modified)."""
+
+    @pytest.mark.integration
+    def test_if_none_match_returns_304(self, integration_client, test_package):
+        """Test If-None-Match with matching ETag returns 304."""
+        project, package = test_package
+        content = b"conditional request test content"
+        expected_hash = compute_sha256(content)
+        upload_test_file(integration_client, project, package, content, tag="cond-etag")
+
+        # Request with matching ETag
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/cond-etag",
+            params={"mode": "proxy"},
+            headers={"If-None-Match": f'"{expected_hash}"'},
+        )
+        assert response.status_code == 304
+        assert response.content == b""  # No body for 304
+
+    @pytest.mark.integration
+    def test_if_none_match_without_quotes(self, integration_client, test_package):
+        """Test If-None-Match works with or without quotes."""
+        project, package = test_package
+        content = b"etag no quotes test"
+        expected_hash = compute_sha256(content)
+        upload_test_file(integration_client, project, package, content, tag="cond-noquote")
+
+        # Request with ETag without quotes
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/cond-noquote",
+            params={"mode": "proxy"},
+            headers={"If-None-Match": expected_hash},
+        )
+        assert response.status_code == 304
+
+    @pytest.mark.integration
+    def test_if_none_match_mismatch_returns_200(self, integration_client, test_package):
+        """Test If-None-Match with non-matching ETag returns 200."""
+        project, package = test_package
+        content = b"etag mismatch test"
+        upload_test_file(integration_client, project, package, content, tag="cond-mismatch")
+
+        # Request with different ETag
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/cond-mismatch",
+            params={"mode": "proxy"},
+            headers={"If-None-Match": '"different-etag-value"'},
+        )
+        assert response.status_code == 200
+        assert response.content == content
+
+    @pytest.mark.integration
+    def test_if_modified_since_returns_304(self, integration_client, test_package):
+        """Test If-Modified-Since with future date returns 304."""
+        project, package = test_package
+        content = b"modified since test"
+        upload_test_file(integration_client, project, package, content, tag="cond-modified")
+
+        # Request with future date (artifact was definitely created before this)
+        future_date = formatdate(time.time() + 86400, usegmt=True)  # Tomorrow
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/cond-modified",
+            params={"mode": "proxy"},
+            headers={"If-Modified-Since": future_date},
+        )
+        assert response.status_code == 304
+
+    @pytest.mark.integration
+    def test_if_modified_since_old_date_returns_200(
+        self, integration_client, test_package
+    ):
+        """Test If-Modified-Since with old date returns 200."""
+        project, package = test_package
+        content = b"old date test"
+        upload_test_file(integration_client, project, package, content, tag="cond-old")
+
+        # Request with old date (2020-01-01)
+        old_date = "Wed, 01 Jan 2020 00:00:00 GMT"
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/cond-old",
+            params={"mode": "proxy"},
+            headers={"If-Modified-Since": old_date},
+        )
+        assert response.status_code == 200
+        assert response.content == content
+
+    @pytest.mark.integration
+    def test_304_includes_etag(self, integration_client, test_package):
+        """Test 304 response includes ETag header."""
+        project, package = test_package
+        content = b"304 etag test"
+        expected_hash = compute_sha256(content)
+        upload_test_file(integration_client, project, package, content, tag="304-etag")
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/304-etag",
+            params={"mode": "proxy"},
+            headers={"If-None-Match": f'"{expected_hash}"'},
+        )
+        assert response.status_code == 304
+        assert response.headers.get("ETag") == f'"{expected_hash}"'
+
+    @pytest.mark.integration
+    def test_304_includes_cache_control(self, integration_client, test_package):
+        """Test 304 response includes Cache-Control header."""
+        project, package = test_package
+        content = b"304 cache test"
+        expected_hash = compute_sha256(content)
+        upload_test_file(integration_client, project, package, content, tag="304-cache")
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/304-cache",
+            params={"mode": "proxy"},
+            headers={"If-None-Match": f'"{expected_hash}"'},
+        )
+        assert response.status_code == 304
+        assert "immutable" in response.headers.get("Cache-Control", "")
+
+
+class TestCachingHeaders:
+    """Tests for caching headers on download responses."""
+
+    @pytest.mark.integration
+    def test_download_includes_cache_control(self, integration_client, test_package):
+        """Test download response includes Cache-Control header."""
+        project, package = test_package
+        content = b"cache control test"
+        upload_test_file(integration_client, project, package, content, tag="cache-ctl")
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/cache-ctl",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        cache_control = response.headers.get("Cache-Control", "")
+        assert "public" in cache_control
+        assert "immutable" in cache_control
+        assert "max-age" in cache_control
+
+    @pytest.mark.integration
+    def test_download_includes_last_modified(self, integration_client, test_package):
+        """Test download response includes Last-Modified header."""
+        project, package = test_package
+        content = b"last modified test"
+        upload_test_file(integration_client, project, package, content, tag="last-mod")
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/last-mod",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert "Last-Modified" in response.headers
+        # Should be in RFC 7231 format
+        last_modified = response.headers["Last-Modified"]
+        assert "GMT" in last_modified
+
+    @pytest.mark.integration
+    def test_download_includes_etag(self, integration_client, test_package):
+        """Test download response includes ETag header."""
+        project, package = test_package
+        content = b"etag header test"
+        expected_hash = compute_sha256(content)
+        upload_test_file(integration_client, project, package, content, tag="etag-hdr")
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/etag-hdr",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert response.headers.get("ETag") == f'"{expected_hash}"'
+
+
+class TestDownloadResume:
+    """Tests for download resume functionality using range requests."""
+
+    @pytest.mark.integration
+    def test_resume_download_after_partial(self, integration_client, test_package):
+        """Test resuming download from where it left off."""
+        project, package = test_package
+        content = b"ABCDEFGHIJ" * 100  # 1000 bytes
+        upload_test_file(integration_client, project, package, content, tag="resume-test")
+
+        # Simulate partial download (first 500 bytes)
+        response1 = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/resume-test",
+            params={"mode": "proxy"},
+            headers={"Range": "bytes=0-499"},
+        )
+        assert response1.status_code == 206
+        first_half = response1.content
+        assert len(first_half) == 500
+
+        # Resume from byte 500
+        response2 = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/resume-test",
+            params={"mode": "proxy"},
+            headers={"Range": "bytes=500-"},
+        )
+        assert response2.status_code == 206
+        second_half = response2.content
+        assert len(second_half) == 500
+
+        # Combine and verify
+        combined = first_half + second_half
+        assert combined == content
+
+    @pytest.mark.integration
+    def test_resume_with_etag_verification(self, integration_client, test_package):
+        """Test that resumed download can verify content hasn't changed."""
+        project, package = test_package
+        content = b"resume etag verification test content"
+        expected_hash = compute_sha256(content)
+        upload_test_file(integration_client, project, package, content, tag="resume-etag")
+
+        # Get ETag from first request
+        response1 = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/resume-etag",
+            params={"mode": "proxy"},
+            headers={"Range": "bytes=0-9"},
+        )
+        assert response1.status_code == 206
+        etag = response1.headers.get("ETag")
+        assert etag == f'"{expected_hash}"'
+
+        # Resume with If-Match to ensure content hasn't changed
+        # (Note: If-Match would fail and return 412 if content changed)
+        response2 = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/resume-etag",
+            params={"mode": "proxy"},
+            headers={"Range": "bytes=10-"},
+        )
+        assert response2.status_code == 206
+        # ETag should be the same
+        assert response2.headers.get("ETag") == etag
+
+
+class TestLargeFileStreaming:
+    """Tests for streaming large files."""
+
+    @pytest.mark.integration
+    def test_stream_1mb_file(self, integration_client, test_package, sized_content):
+        """Test streaming a 1MB file."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_1MB, seed=500)
+
+        upload_test_file(integration_client, project, package, content, tag="stream-1mb")
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/stream-1mb",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert len(response.content) == SIZE_1MB
+        assert compute_sha256(response.content) == expected_hash
+
+    @pytest.mark.integration
+    def test_stream_large_file_has_correct_headers(
+        self, integration_client, test_package, sized_content
+    ):
+        """Test that large file streaming has correct headers."""
+        project, package = test_package
+        content, expected_hash = sized_content(SIZE_100KB, seed=501)
+
+        upload_test_file(integration_client, project, package, content, tag="stream-hdr")
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/stream-hdr",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert int(response.headers.get("Content-Length", 0)) == SIZE_100KB
+        assert response.headers.get("X-Checksum-SHA256") == expected_hash
+        assert response.headers.get("Accept-Ranges") == "bytes"
+
+    @pytest.mark.integration
+    def test_range_request_on_large_file(
+        self, integration_client, test_package, sized_content
+    ):
+        """Test range request on a larger file."""
+        project, package = test_package
+        content, _ = sized_content(SIZE_100KB, seed=502)
+
+        upload_test_file(integration_client, project, package, content, tag="range-large")
+
+        # Request a slice from the middle
+        start = 50000
+        end = 50999
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/range-large",
+            params={"mode": "proxy"},
+            headers={"Range": f"bytes={start}-{end}"},
+        )
+        assert response.status_code == 206
+        assert len(response.content) == 1000
+        assert response.content == content[start : end + 1]
+
+
+class TestDownloadModes:
+    """Tests for different download modes."""
+
+    @pytest.mark.integration
+    def test_proxy_mode_streams_content(self, integration_client, test_package):
+        """Test proxy mode streams content through backend."""
+        project, package = test_package
+        content = b"proxy mode test content"
+        upload_test_file(integration_client, project, package, content, tag="mode-proxy")
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/mode-proxy",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert response.content == content
+
+    @pytest.mark.integration
+    def test_presigned_mode_returns_url(self, integration_client, test_package):
+        """Test presigned mode returns JSON with URL."""
+        project, package = test_package
+        content = b"presigned mode test"
+        upload_test_file(integration_client, project, package, content, tag="mode-presign")
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/mode-presign",
+            params={"mode": "presigned"},
+        )
+        assert response.status_code == 200
+        data = response.json()
+        assert "url" in data
+        assert "expires_at" in data
+        assert data["url"].startswith("http")
+
+    @pytest.mark.integration
+    def test_redirect_mode_returns_302(self, integration_client, test_package):
+        """Test redirect mode returns 302 to presigned URL."""
+        project, package = test_package
+        content = b"redirect mode test"
+        upload_test_file(integration_client, project, package, content, tag="mode-redir")
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/mode-redir",
+            params={"mode": "redirect"},
+            follow_redirects=False,
+        )
+        assert response.status_code == 302
+        assert "Location" in response.headers
+
+
+class TestIntegrityDuringStreaming:
+    """Tests for data integrity during streaming downloads."""
+
+    @pytest.mark.integration
+    def test_checksum_header_matches_content(self, integration_client, test_package):
+        """Test X-Checksum-SHA256 header matches actual downloaded content."""
+        project, package = test_package
+        content = b"integrity check content"
+        expected_hash = compute_sha256(content)
+        upload_test_file(integration_client, project, package, content, tag="integrity")
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/integrity",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+
+        header_hash = response.headers.get("X-Checksum-SHA256")
+        actual_hash = compute_sha256(response.content)
+
+        assert header_hash == expected_hash
+        assert actual_hash == expected_hash
+        assert header_hash == actual_hash
+
+    @pytest.mark.integration
+    def test_etag_matches_content_hash(self, integration_client, test_package):
+        """Test ETag header matches content hash."""
+        project, package = test_package
+        content = b"etag integrity test"
+        expected_hash = compute_sha256(content)
+        upload_test_file(integration_client, project, package, content, tag="etag-int")
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/etag-int",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+
+        etag = response.headers.get("ETag", "").strip('"')
+        actual_hash = compute_sha256(response.content)
+
+        assert etag == expected_hash
+        assert actual_hash == expected_hash
+
+    @pytest.mark.integration
+    def test_digest_header_present(self, integration_client, test_package):
+        """Test Digest header is present in RFC 3230 format."""
+        project, package = test_package
+        content = b"digest header test"
+        upload_test_file(integration_client, project, package, content, tag="digest")
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/digest",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert "Digest" in response.headers
+        assert response.headers["Digest"].startswith("sha-256=")

backend/tests/integration/test_upload_download_api.py

@@ -10,6 +10,7 @@ Tests cover:
 - S3 storage verification
 """
 
+import os
 import pytest
 import io
 import threading
@@ -25,6 +26,19 @@ from tests.factories import (
 class TestUploadBasics:
     """Tests for basic upload functionality."""
 
+    @pytest.mark.integration
+    def test_upload_returns_200(self, integration_client, test_package):
+        """Test upload with valid file returns 200."""
+        project, package = test_package
+        content = b"valid file upload test"
+
+        files = {"file": ("test.bin", io.BytesIO(content), "application/octet-stream")}
+        response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+        )
+        assert response.status_code == 200
+
     @pytest.mark.integration
     def test_upload_returns_artifact_id(self, integration_client, test_package):
         """Test upload returns the artifact ID (SHA256 hash)."""
@@ -101,6 +115,83 @@ class TestUploadBasics:
         assert "created_at" in result
         assert result["created_at"] is not None
 
+    @pytest.mark.integration
+    def test_upload_without_tag_succeeds(self, integration_client, test_package):
+        """Test upload without tag succeeds (no tag created)."""
+        project, package = test_package
+        content = b"upload without tag test"
+        expected_hash = compute_sha256(content)
+
+        files = {"file": ("no_tag.bin", io.BytesIO(content), "application/octet-stream")}
+        response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+            # No tag parameter
+        )
+        assert response.status_code == 200
+        result = response.json()
+        assert result["artifact_id"] == expected_hash
+
+        # Verify no tag was created - list tags and check
+        tags_response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/tags"
+        )
+        assert tags_response.status_code == 200
+        tags = tags_response.json()
+        # Filter for tags pointing to this artifact
+        artifact_tags = [t for t in tags.get("items", tags) if t.get("artifact_id") == expected_hash]
+        assert len(artifact_tags) == 0, "Tag should not be created when not specified"
+
+    @pytest.mark.integration
+    def test_upload_creates_artifact_in_database(self, integration_client, test_package):
+        """Test upload creates artifact record in database."""
+        project, package = test_package
+        content = b"database artifact test"
+        expected_hash = compute_sha256(content)
+
+        upload_test_file(integration_client, project, package, content)
+
+        # Verify artifact exists via API
+        response = integration_client.get(f"/api/v1/artifact/{expected_hash}")
+        assert response.status_code == 200
+        artifact = response.json()
+        assert artifact["id"] == expected_hash
+        assert artifact["size"] == len(content)
+
+    @pytest.mark.integration
+    @pytest.mark.requires_direct_s3
+    def test_upload_creates_object_in_s3(self, integration_client, test_package):
+        """Test upload creates object in S3 storage."""
+        project, package = test_package
+        content = b"s3 object creation test"
+        expected_hash = compute_sha256(content)
+
+        upload_test_file(integration_client, project, package, content)
+
+        # Verify S3 object exists
+        assert s3_object_exists(expected_hash), "S3 object should exist after upload"
+
+    @pytest.mark.integration
+    def test_upload_with_tag_creates_tag_record(self, integration_client, test_package):
+        """Test upload with tag creates tag record."""
+        project, package = test_package
+        content = b"tag creation test"
+        expected_hash = compute_sha256(content)
+        tag_name = "my-tag-v1"
+
+        upload_test_file(
+            integration_client, project, package, content, tag=tag_name
+        )
+
+        # Verify tag exists
+        tags_response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/tags"
+        )
+        assert tags_response.status_code == 200
+        tags = tags_response.json()
+        tag_names = [t["name"] for t in tags.get("items", tags)]
+        assert tag_name in tag_names
+
 
 class TestDuplicateUploads:
     """Tests for duplicate upload deduplication behavior."""
@@ -248,6 +339,23 @@ class TestDownload:
         assert response.status_code == 200
         assert response.content == original_content
 
+    @pytest.mark.integration
+    def test_download_by_tag_prefix(self, integration_client, test_package):
+        """Test downloading artifact using tag: prefix."""
+        project, package = test_package
+        original_content = b"download by tag prefix test"
+
+        upload_test_file(
+            integration_client, project, package, original_content, tag="prefix-tag"
+        )
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/tag:prefix-tag",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert response.content == original_content
+
     @pytest.mark.integration
     def test_download_nonexistent_tag(self, integration_client, test_package):
         """Test downloading nonexistent tag returns 404."""
@@ -258,6 +366,33 @@ class TestDownload:
         )
         assert response.status_code == 404
 
+    @pytest.mark.integration
+    def test_download_nonexistent_artifact(self, integration_client, test_package):
+        """Test downloading nonexistent artifact ID returns 404."""
+        project, package = test_package
+        fake_hash = "0" * 64
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/artifact:{fake_hash}"
+        )
+        assert response.status_code == 404
+
+    @pytest.mark.integration
+    def test_download_from_nonexistent_project(self, integration_client, unique_test_id):
+        """Test downloading from nonexistent project returns 404."""
+        response = integration_client.get(
+            f"/api/v1/project/nonexistent-project-{unique_test_id}/somepackage/+/sometag"
+        )
+        assert response.status_code == 404
+
+    @pytest.mark.integration
+    def test_download_from_nonexistent_package(self, integration_client, test_project, unique_test_id):
+        """Test downloading from nonexistent package returns 404."""
+        response = integration_client.get(
+            f"/api/v1/project/{test_project}/nonexistent-package-{unique_test_id}/+/sometag"
+        )
+        assert response.status_code == 404
+
     @pytest.mark.integration
     def test_content_matches_original(self, integration_client, test_package):
         """Test downloaded content matches original exactly."""
@@ -275,6 +410,111 @@ class TestDownload:
         assert response.content == original_content
 
 
+class TestDownloadHeaders:
+    """Tests for download response headers."""
+
+    @pytest.mark.integration
+    def test_download_content_type_header(self, integration_client, test_package):
+        """Test download returns correct Content-Type header."""
+        project, package = test_package
+        content = b"content type header test"
+
+        upload_test_file(
+            integration_client, project, package, content,
+            filename="test.txt", tag="content-type-test"
+        )
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/content-type-test",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        # Content-Type should be set (either text/plain or application/octet-stream)
+        assert "content-type" in response.headers
+
+    @pytest.mark.integration
+    def test_download_content_length_header(self, integration_client, test_package):
+        """Test download returns correct Content-Length header."""
+        project, package = test_package
+        content = b"content length header test - exactly 41 bytes!"
+        expected_length = len(content)
+
+        upload_test_file(
+            integration_client, project, package, content, tag="content-length-test"
+        )
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/content-length-test",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert "content-length" in response.headers
+        assert int(response.headers["content-length"]) == expected_length
+
+    @pytest.mark.integration
+    def test_download_content_disposition_header(self, integration_client, test_package):
+        """Test download returns correct Content-Disposition header."""
+        project, package = test_package
+        content = b"content disposition test"
+        filename = "my-test-file.bin"
+
+        upload_test_file(
+            integration_client, project, package, content,
+            filename=filename, tag="disposition-test"
+        )
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/disposition-test",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert "content-disposition" in response.headers
+        disposition = response.headers["content-disposition"]
+        assert "attachment" in disposition
+        assert filename in disposition
+
+    @pytest.mark.integration
+    def test_download_checksum_headers(self, integration_client, test_package):
+        """Test download returns checksum headers."""
+        project, package = test_package
+        content = b"checksum header test content"
+        expected_hash = compute_sha256(content)
+
+        upload_test_file(
+            integration_client, project, package, content, tag="checksum-headers"
+        )
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/checksum-headers",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        # Check for checksum headers
+        assert "x-checksum-sha256" in response.headers
+        assert response.headers["x-checksum-sha256"] == expected_hash
+
+    @pytest.mark.integration
+    def test_download_etag_header(self, integration_client, test_package):
+        """Test download returns ETag header (artifact ID)."""
+        project, package = test_package
+        content = b"etag header test"
+        expected_hash = compute_sha256(content)
+
+        upload_test_file(
+            integration_client, project, package, content, tag="etag-test"
+        )
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/etag-test",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert "etag" in response.headers
+        # ETag should contain the artifact ID (hash)
+        etag = response.headers["etag"].strip('"')
+        assert etag == expected_hash
+
+
 class TestConcurrentUploads:
     """Tests for concurrent upload handling."""
 
@@ -301,7 +541,7 @@ class TestConcurrentUploads:
             try:
                 from httpx import Client
 
-                base_url = "http://localhost:8080"
+                base_url = os.environ.get("ORCHARD_TEST_URL", "http://localhost:8080")
                 with Client(base_url=base_url, timeout=30.0) as client:
                     files = {
                         "file": (
@@ -397,6 +637,7 @@ class TestUploadFailureCleanup:
     """Tests for cleanup when uploads fail."""
 
     @pytest.mark.integration
+    @pytest.mark.requires_direct_s3
     def test_upload_failure_invalid_project_no_orphaned_s3(
         self, integration_client, unique_test_id
     ):
@@ -419,6 +660,7 @@ class TestUploadFailureCleanup:
         )
 
     @pytest.mark.integration
+    @pytest.mark.requires_direct_s3
     def test_upload_failure_invalid_package_no_orphaned_s3(
         self, integration_client, test_project, unique_test_id
     ):
@@ -466,6 +708,7 @@ class TestS3StorageVerification:
     """Tests to verify S3 storage behavior."""
 
     @pytest.mark.integration
+    @pytest.mark.requires_direct_s3
     def test_s3_single_object_after_duplicates(
         self, integration_client, test_package, unique_test_id
     ):
@@ -521,6 +764,7 @@ class TestSecurityPathTraversal:
     """
 
     @pytest.mark.integration
+    @pytest.mark.requires_direct_s3
     def test_path_traversal_in_filename_stored_safely(
         self, integration_client, test_package
     ):

backend/tests/integration/test_version_api.py

@@ -0,0 +1,347 @@
+"""
+Integration tests for package version API endpoints.
+
+Tests cover:
+- Version creation via upload
+- Version auto-detection from filename
+- Version listing and retrieval
+- Download by version prefix
+- Version deletion
+"""
+
+import pytest
+import io
+from tests.factories import (
+    compute_sha256,
+    upload_test_file,
+)
+
+
+class TestVersionCreation:
+    """Tests for creating versions via upload."""
+
+    @pytest.mark.integration
+    def test_upload_with_explicit_version(self, integration_client, test_package):
+        """Test upload with explicit version parameter creates version record."""
+        project, package = test_package
+        content = b"version creation test"
+        expected_hash = compute_sha256(content)
+
+        files = {"file": ("app.tar.gz", io.BytesIO(content), "application/octet-stream")}
+        response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+            data={"version": "1.0.0"},
+        )
+        assert response.status_code == 200
+        result = response.json()
+        assert result["artifact_id"] == expected_hash
+        assert result.get("version") == "1.0.0"
+        assert result.get("version_source") == "explicit"
+
+    @pytest.mark.integration
+    def test_upload_with_version_and_tag(self, integration_client, test_package):
+        """Test upload with both version and tag creates both records."""
+        project, package = test_package
+        content = b"version and tag test"
+
+        files = {"file": ("app.tar.gz", io.BytesIO(content), "application/octet-stream")}
+        response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+            data={"version": "2.0.0", "tag": "latest"},
+        )
+        assert response.status_code == 200
+        result = response.json()
+        assert result.get("version") == "2.0.0"
+
+        # Verify tag was also created
+        tags_response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/tags"
+        )
+        assert tags_response.status_code == 200
+        tags = tags_response.json()
+        tag_names = [t["name"] for t in tags.get("items", tags)]
+        assert "latest" in tag_names
+
+    @pytest.mark.integration
+    def test_duplicate_version_same_content_succeeds(self, integration_client, test_package):
+        """Test uploading same version with same content succeeds (deduplication)."""
+        project, package = test_package
+        content = b"version dedup test"
+
+        # First upload with version
+        files1 = {"file": ("app1.tar.gz", io.BytesIO(content), "application/octet-stream")}
+        response1 = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files1,
+            data={"version": "3.0.0"},
+        )
+        assert response1.status_code == 200
+
+        # Second upload with same version and same content succeeds
+        files2 = {"file": ("app2.tar.gz", io.BytesIO(content), "application/octet-stream")}
+        response2 = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files2,
+            data={"version": "3.0.0"},
+        )
+        # This succeeds because it's the same artifact (deduplication)
+        assert response2.status_code == 200
+
+
+class TestVersionAutoDetection:
+    """Tests for automatic version detection from filename."""
+
+    @pytest.mark.integration
+    def test_version_detected_from_filename_tarball(self, integration_client, test_package):
+        """Test version is auto-detected from tarball filename or metadata."""
+        project, package = test_package
+        content = b"auto detect version tarball"
+
+        files = {"file": ("myapp-1.2.3.tar.gz", io.BytesIO(content), "application/octet-stream")}
+        response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+        )
+        assert response.status_code == 200
+        result = response.json()
+        assert result.get("version") == "1.2.3"
+        # Version source can be 'filename' or 'metadata' depending on detection order
+        assert result.get("version_source") in ["filename", "metadata"]
+
+    @pytest.mark.integration
+    def test_version_detected_from_filename_zip(self, integration_client, test_package):
+        """Test version is auto-detected from zip filename."""
+        project, package = test_package
+        content = b"auto detect version zip"
+
+        files = {"file": ("package-2.0.0.zip", io.BytesIO(content), "application/octet-stream")}
+        response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+        )
+        assert response.status_code == 200
+        result = response.json()
+        assert result.get("version") == "2.0.0"
+        assert result.get("version_source") == "filename"
+
+    @pytest.mark.integration
+    def test_explicit_version_overrides_filename(self, integration_client, test_package):
+        """Test explicit version parameter overrides filename detection."""
+        project, package = test_package
+        content = b"explicit override test"
+
+        files = {"file": ("myapp-1.0.0.tar.gz", io.BytesIO(content), "application/octet-stream")}
+        response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+            data={"version": "9.9.9"},
+        )
+        assert response.status_code == 200
+        result = response.json()
+        assert result.get("version") == "9.9.9"
+        assert result.get("version_source") == "explicit"
+
+    @pytest.mark.integration
+    def test_no_version_detected_from_plain_filename(self, integration_client, test_package):
+        """Test no version is created for filenames without version pattern."""
+        project, package = test_package
+        content = b"no version in filename"
+
+        files = {"file": ("plain-file.bin", io.BytesIO(content), "application/octet-stream")}
+        response = integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+        )
+        assert response.status_code == 200
+        result = response.json()
+        # Version should be None or not present
+        assert result.get("version") is None
+
+
+class TestVersionListing:
+    """Tests for listing and retrieving versions."""
+
+    @pytest.mark.integration
+    def test_list_versions(self, integration_client, test_package):
+        """Test listing all versions for a package."""
+        project, package = test_package
+
+        # Create multiple versions
+        for ver in ["1.0.0", "1.1.0", "2.0.0"]:
+            content = f"version {ver} content".encode()
+            files = {"file": (f"app-{ver}.tar.gz", io.BytesIO(content), "application/octet-stream")}
+            response = integration_client.post(
+                f"/api/v1/project/{project}/{package}/upload",
+                files=files,
+                data={"version": ver},
+            )
+            assert response.status_code == 200
+
+        # List versions
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/versions"
+        )
+        assert response.status_code == 200
+        data = response.json()
+        versions = [v["version"] for v in data.get("items", data)]
+        assert "1.0.0" in versions
+        assert "1.1.0" in versions
+        assert "2.0.0" in versions
+
+    @pytest.mark.integration
+    def test_get_specific_version(self, integration_client, test_package):
+        """Test getting details for a specific version."""
+        project, package = test_package
+        content = b"specific version test"
+        expected_hash = compute_sha256(content)
+
+        # Create version
+        files = {"file": ("app-4.0.0.tar.gz", io.BytesIO(content), "application/octet-stream")}
+        integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+            data={"version": "4.0.0"},
+        )
+
+        # Get version details
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/versions/4.0.0"
+        )
+        assert response.status_code == 200
+        data = response.json()
+        assert data["version"] == "4.0.0"
+        assert data["artifact_id"] == expected_hash
+
+    @pytest.mark.integration
+    def test_get_nonexistent_version_returns_404(self, integration_client, test_package):
+        """Test getting nonexistent version returns 404."""
+        project, package = test_package
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/versions/99.99.99"
+        )
+        assert response.status_code == 404
+
+
+class TestDownloadByVersion:
+    """Tests for downloading artifacts by version."""
+
+    @pytest.mark.integration
+    def test_download_by_version_prefix(self, integration_client, test_package):
+        """Test downloading artifact using version: prefix."""
+        project, package = test_package
+        content = b"download by version test"
+        expected_hash = compute_sha256(content)
+
+        # Upload with version
+        files = {"file": ("app.tar.gz", io.BytesIO(content), "application/octet-stream")}
+        integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+            data={"version": "5.0.0"},
+        )
+
+        # Download by version prefix
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/version:5.0.0",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert response.content == content
+
+    @pytest.mark.integration
+    def test_download_nonexistent_version_returns_404(self, integration_client, test_package):
+        """Test downloading nonexistent version returns 404."""
+        project, package = test_package
+
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/version:99.0.0"
+        )
+        assert response.status_code == 404
+
+    @pytest.mark.integration
+    def test_version_resolution_priority(self, integration_client, test_package):
+        """Test that version: prefix explicitly resolves to version, not tag."""
+        project, package = test_package
+        version_content = b"this is the version content"
+        tag_content = b"this is the tag content"
+
+        # Create a version 6.0.0
+        files1 = {"file": ("app-v.tar.gz", io.BytesIO(version_content), "application/octet-stream")}
+        integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files1,
+            data={"version": "6.0.0"},
+        )
+
+        # Create a tag named "6.0.0" pointing to different content
+        files2 = {"file": ("app-t.tar.gz", io.BytesIO(tag_content), "application/octet-stream")}
+        integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files2,
+            data={"tag": "6.0.0"},
+        )
+
+        # Download with version: prefix should get version content
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/version:6.0.0",
+            params={"mode": "proxy"},
+        )
+        assert response.status_code == 200
+        assert response.content == version_content
+
+        # Download with tag: prefix should get tag content
+        response2 = integration_client.get(
+            f"/api/v1/project/{project}/{package}/+/tag:6.0.0",
+            params={"mode": "proxy"},
+        )
+        assert response2.status_code == 200
+        assert response2.content == tag_content
+
+
+class TestVersionDeletion:
+    """Tests for deleting versions."""
+
+    @pytest.mark.integration
+    def test_delete_version(self, integration_client, test_package):
+        """Test deleting a version."""
+        project, package = test_package
+        content = b"delete version test"
+
+        # Create version
+        files = {"file": ("app.tar.gz", io.BytesIO(content), "application/octet-stream")}
+        integration_client.post(
+            f"/api/v1/project/{project}/{package}/upload",
+            files=files,
+            data={"version": "7.0.0"},
+        )
+
+        # Verify version exists
+        response = integration_client.get(
+            f"/api/v1/project/{project}/{package}/versions/7.0.0"
+        )
+        assert response.status_code == 200
+
+        # Delete version - returns 204 No Content on success
+        delete_response = integration_client.delete(
+            f"/api/v1/project/{project}/{package}/versions/7.0.0"
+        )
+        assert delete_response.status_code == 204
+
+        # Verify version no longer exists
+        response2 = integration_client.get(
+            f"/api/v1/project/{project}/{package}/versions/7.0.0"
+        )
+        assert response2.status_code == 404
+
+    @pytest.mark.integration
+    def test_delete_nonexistent_version_returns_404(self, integration_client, test_package):
+        """Test deleting nonexistent version returns 404."""
+        project, package = test_package
+
+        response = integration_client.delete(
+            f"/api/v1/project/{project}/{package}/versions/99.0.0"
+        )
+        assert response.status_code == 404

backend/tests/integration/test_versions_api.py

@@ -0,0 +1,412 @@
+"""
+Integration tests for version API endpoints.
+
+Tests cover:
+- Version creation via upload
+- Version auto-detection from filename
+- Version listing with pagination
+- Version deletion
+- Download by version ref
+- ref_count behavior with version operations
+"""
+
+import pytest
+from tests.factories import upload_test_file
+
+
+class TestVersionCreation:
+    """Tests for version creation during upload."""
+
+    @pytest.mark.integration
+    def test_upload_with_explicit_version(self, integration_client, test_package):
+        """Test creating a version via explicit version parameter."""
+        project_name, package_name = test_package
+
+        result = upload_test_file(
+            integration_client,
+            project_name,
+            package_name,
+            b"version create test",
+            tag="latest",
+            version="1.0.0",
+        )
+
+        assert result["tag"] == "latest"
+        assert result["version"] == "1.0.0"
+        assert result["version_source"] == "explicit"
+        assert result["artifact_id"]
+
+    @pytest.mark.integration
+    def test_upload_with_version_auto_detect_from_tarball(
+        self, integration_client, test_package
+    ):
+        """Test version auto-detection from tarball filename pattern."""
+        project_name, package_name = test_package
+
+        result = upload_test_file(
+            integration_client,
+            project_name,
+            package_name,
+            b"auto version test",
+            filename="myapp-2.1.0.tar.gz",
+        )
+
+        assert result["version"] == "2.1.0"
+        # Tarball metadata extractor parses version from filename
+        assert result["version_source"] == "metadata"
+
+    @pytest.mark.integration
+    def test_upload_with_version_auto_detect_v_prefix(
+        self, integration_client, test_package
+    ):
+        """Test version auto-detection strips 'v' prefix from tarball filename."""
+        project_name, package_name = test_package
+
+        result = upload_test_file(
+            integration_client,
+            project_name,
+            package_name,
+            b"v prefix test",
+            filename="package-v3.0.0.tar.gz",
+        )
+
+        assert result["version"] == "3.0.0"
+        # Tarball metadata extractor parses version from filename
+        assert result["version_source"] == "metadata"
+
+    @pytest.mark.integration
+    def test_upload_duplicate_version_warning(self, integration_client, test_package):
+        """Test that duplicate version during upload returns response without error."""
+        project_name, package_name = test_package
+
+        # Upload with version 1.0.0
+        upload_test_file(
+            integration_client,
+            project_name,
+            package_name,
+            b"first upload",
+            version="1.0.0",
+        )
+
+        # Upload different content with same version - should succeed but no new version
+        result = upload_test_file(
+            integration_client,
+            project_name,
+            package_name,
+            b"second upload different content",
+            version="1.0.0",
+        )
+
+        # Upload succeeds but version may not be set (duplicate)
+        assert result["artifact_id"]
+
+
+class TestVersionCRUD:
+    """Tests for version list, get, delete operations."""
+
+    @pytest.mark.integration
+    def test_list_versions(self, integration_client, test_package):
+        """Test listing versions for a package."""
+        project_name, package_name = test_package
+
+        # Create some versions
+        upload_test_file(
+            integration_client,
+            project_name,
+            package_name,
+            b"v1 content",
+            version="1.0.0",
+        )
+        upload_test_file(
+            integration_client,
+            project_name,
+            package_name,
+            b"v2 content",
+            version="2.0.0",
+        )
+
+        response = integration_client.get(
+            f"/api/v1/project/{project_name}/{package_name}/versions"
+        )
+        assert response.status_code == 200
+
+        data = response.json()
+        assert "items" in data
+        assert "pagination" in data
+
+        versions = [v["version"] for v in data["items"]]
+        assert "1.0.0" in versions
+        assert "2.0.0" in versions
+
+    @pytest.mark.integration
+    def test_list_versions_with_artifact_info(self, integration_client, test_package):
+        """Test that version list includes artifact metadata."""
+        project_name, package_name = test_package
+
+        upload_test_file(
+            integration_client,
+            project_name,
+            package_name,
+            b"version with info",
+            version="1.0.0",
+            tag="release",
+        )
+
+        response = integration_client.get(
+            f"/api/v1/project/{project_name}/{package_name}/versions"
+        )
+        assert response.status_code == 200
+
+        data = response.json()
+        assert len(data["items"]) >= 1
+
+        version_item = next(
+            (v for v in data["items"] if v["version"] == "1.0.0"), None
+        )
+        assert version_item is not None
+        assert "size" in version_item
+        assert "artifact_id" in version_item
+        assert "tags" in version_item
+        assert "release" in version_item["tags"]
+
+    @pytest.mark.integration
+    def test_get_version(self, integration_client, test_package):
+        """Test getting a specific version."""
+        project_name, package_name = test_package
+
+        upload_result = upload_test_file(
+            integration_client,
+            project_name,
+            package_name,
+            b"get version test",
+            version="3.0.0",
+        )
+
+        response = integration_client.get(
+            f"/api/v1/project/{project_name}/{package_name}/versions/3.0.0"
+        )
+        assert response.status_code == 200
+
+        data = response.json()
+        assert data["version"] == "3.0.0"
+        assert data["artifact_id"] == upload_result["artifact_id"]
+        assert data["version_source"] == "explicit"
+
+    @pytest.mark.integration
+    def test_get_version_not_found(self, integration_client, test_package):
+        """Test getting a non-existent version returns 404."""
+        project_name, package_name = test_package
+
+        response = integration_client.get(
+            f"/api/v1/project/{project_name}/{package_name}/versions/99.99.99"
+        )
+        assert response.status_code == 404
+
+    @pytest.mark.integration
+    def test_delete_version(self, integration_client, test_package):
+        """Test deleting a version."""
+        project_name, package_name = test_package
+
+        upload_test_file(
+            integration_client,
+            project_name,
+            package_name,
+            b"delete version test",
+            version="4.0.0",
+        )
+
+        # Delete version
+        response = integration_client.delete(
+            f"/api/v1/project/{project_name}/{package_name}/versions/4.0.0"
+        )
+        assert response.status_code == 204
+
+        # Verify deleted
+        response = integration_client.get(
+            f"/api/v1/project/{project_name}/{package_name}/versions/4.0.0"
+        )
+        assert response.status_code == 404
+
+
+class TestVersionDownload:
+    """Tests for downloading artifacts by version reference."""
+
+    @pytest.mark.integration
+    def test_download_by_version_prefix(self, integration_client, test_package):
+        """Test downloading an artifact using version: prefix."""
+        project_name, package_name = test_package
+        content = b"download by version test"
+
+        upload_test_file(
+            integration_client,
+            project_name,
+            package_name,
+            content,
+            version="5.0.0",
+        )
+
+        response = integration_client.get(
+            f"/api/v1/project/{project_name}/{package_name}/+/version:5.0.0",
+            follow_redirects=False,
+        )
+
+        # Should either redirect or return content
+        assert response.status_code in [200, 302, 307]
+
+    @pytest.mark.integration
+    def test_download_by_implicit_version(self, integration_client, test_package):
+        """Test downloading an artifact using version number directly (no prefix)."""
+        project_name, package_name = test_package
+        content = b"implicit version download test"
+
+        upload_test_file(
+            integration_client,
+            project_name,
+            package_name,
+            content,
+            version="6.0.0",
+        )
+
+        response = integration_client.get(
+            f"/api/v1/project/{project_name}/{package_name}/+/6.0.0",
+            follow_redirects=False,
+        )
+
+        # Should resolve version first (before tag)
+        assert response.status_code in [200, 302, 307]
+
+    @pytest.mark.integration
+    def test_version_takes_precedence_over_tag(self, integration_client, test_package):
+        """Test that version is checked before tag when resolving refs."""
+        project_name, package_name = test_package
+
+        # Upload with version "1.0"
+        version_result = upload_test_file(
+            integration_client,
+            project_name,
+            package_name,
+            b"version content",
+            version="1.0",
+        )
+
+        # Create a tag with the same name "1.0" pointing to different artifact
+        tag_result = upload_test_file(
+            integration_client,
+            project_name,
+            package_name,
+            b"tag content different",
+            tag="1.0",
+        )
+
+        # Download by "1.0" should resolve to version, not tag
+        # Since version:1.0 artifact was uploaded first
+        response = integration_client.get(
+            f"/api/v1/project/{project_name}/{package_name}/+/1.0",
+            follow_redirects=False,
+        )
+
+        assert response.status_code in [200, 302, 307]
+
+
+class TestTagVersionEnrichment:
+    """Tests for tag responses including version information."""
+
+    @pytest.mark.integration
+    def test_tag_response_includes_version(self, integration_client, test_package):
+        """Test that tag responses include version of the artifact."""
+        project_name, package_name = test_package
+
+        # Upload with both version and tag
+        upload_test_file(
+            integration_client,
+            project_name,
+            package_name,
+            b"enriched tag test",
+            version="7.0.0",
+            tag="stable",
+        )
+
+        # Get tag and check version field
+        response = integration_client.get(
+            f"/api/v1/project/{project_name}/{package_name}/tags/stable"
+        )
+        assert response.status_code == 200
+
+        data = response.json()
+        assert data["name"] == "stable"
+        assert data["version"] == "7.0.0"
+
+    @pytest.mark.integration
+    def test_tag_list_includes_versions(self, integration_client, test_package):
+        """Test that tag list responses include version for each tag."""
+        project_name, package_name = test_package
+
+        upload_test_file(
+            integration_client,
+            project_name,
+            package_name,
+            b"list version test",
+            version="8.0.0",
+            tag="latest",
+        )
+
+        response = integration_client.get(
+            f"/api/v1/project/{project_name}/{package_name}/tags"
+        )
+        assert response.status_code == 200
+
+        data = response.json()
+        tag_item = next((t for t in data["items"] if t["name"] == "latest"), None)
+        assert tag_item is not None
+        assert tag_item.get("version") == "8.0.0"
+
+
+class TestVersionPagination:
+    """Tests for version listing pagination and sorting."""
+
+    @pytest.mark.integration
+    def test_versions_pagination(self, integration_client, test_package):
+        """Test version listing respects pagination."""
+        project_name, package_name = test_package
+
+        response = integration_client.get(
+            f"/api/v1/project/{project_name}/{package_name}/versions?limit=5"
+        )
+        assert response.status_code == 200
+
+        data = response.json()
+        assert "pagination" in data
+        assert data["pagination"]["limit"] == 5
+
+    @pytest.mark.integration
+    def test_versions_sorting(self, integration_client, test_package):
+        """Test version listing can be sorted."""
+        project_name, package_name = test_package
+
+        # Create versions with different timestamps
+        upload_test_file(
+            integration_client,
+            project_name,
+            package_name,
+            b"sort test 1",
+            version="1.0.0",
+        )
+        upload_test_file(
+            integration_client,
+            project_name,
+            package_name,
+            b"sort test 2",
+            version="2.0.0",
+        )
+
+        # Test ascending sort
+        response = integration_client.get(
+            f"/api/v1/project/{project_name}/{package_name}/versions?sort=version&order=asc"
+        )
+        assert response.status_code == 200
+
+        data = response.json()
+        versions = [v["version"] for v in data["items"]]
+        # First version should be 1.0.0 when sorted ascending
+        if len(versions) >= 2:
+            assert versions.index("1.0.0") < versions.index("2.0.0")

docs/integrity-verification.md

@@ -0,0 +1,294 @@
+# Integrity Verification
+
+Orchard uses content-addressable storage with SHA256 hashing to ensure artifact integrity. This document describes how integrity verification works and how to use it.
+
+## How It Works
+
+### Content-Addressable Storage
+
+Orchard stores artifacts using their SHA256 hash as the unique identifier. This provides several benefits:
+
+1. **Automatic deduplication**: Identical content is stored only once
+2. **Built-in integrity**: The artifact ID *is* the content hash
+3. **Tamper detection**: Any modification changes the hash, making corruption detectable
+
+When you upload a file:
+1. Orchard computes the SHA256 hash of the content
+2. The hash becomes the artifact ID (64-character hex string)
+3. The file is stored in S3 at `fruits/{hash[0:2]}/{hash[2:4]}/{hash}`
+4. The hash and metadata are recorded in the database
+
+### Hash Format
+
+- Algorithm: SHA256
+- Format: 64-character lowercase hexadecimal string
+- Example: `dffd6021bb2bd5b0af676290809ec3a53191dd81c7f70a4b28688a362182986f`
+
+## Client-Side Verification
+
+### Before Upload
+
+Compute the hash locally before uploading to verify the server received your content correctly:
+
+```python
+import hashlib
+
+def compute_sha256(content: bytes) -> str:
+    return hashlib.sha256(content).hexdigest()
+
+# Compute hash before upload
+content = open("myfile.tar.gz", "rb").read()
+local_hash = compute_sha256(content)
+
+# Upload the file
+response = requests.post(
+    f"{base_url}/api/v1/project/{project}/{package}/upload",
+    files={"file": ("myfile.tar.gz", content)},
+)
+result = response.json()
+
+# Verify server computed the same hash
+assert result["artifact_id"] == local_hash, "Hash mismatch!"
+```
+
+### Providing Expected Hash on Upload
+
+You can provide the expected hash in the upload request. The server will reject the upload if the computed hash doesn't match:
+
+```python
+response = requests.post(
+    f"{base_url}/api/v1/project/{project}/{package}/upload",
+    files={"file": ("myfile.tar.gz", content)},
+    headers={"X-Checksum-SHA256": local_hash},
+)
+
+# Returns 422 if hash doesn't match
+if response.status_code == 422:
+    print("Checksum mismatch - upload rejected")
+```
+
+### After Download
+
+Verify downloaded content matches the expected hash using response headers:
+
+```python
+response = requests.get(
+    f"{base_url}/api/v1/project/{project}/{package}/+/{tag}",
+    params={"mode": "proxy"},
+)
+
+# Get expected hash from header
+expected_hash = response.headers.get("X-Checksum-SHA256")
+
+# Compute hash of downloaded content
+actual_hash = compute_sha256(response.content)
+
+# Verify
+if actual_hash != expected_hash:
+    raise Exception(f"Integrity check failed! Expected {expected_hash}, got {actual_hash}")
+```
+
+### Response Headers for Verification
+
+Download responses include multiple headers for verification:
+
+| Header | Format | Description |
+|--------|--------|-------------|
+| `X-Checksum-SHA256` | Hex string | SHA256 hash (64 chars) |
+| `ETag` | `"<hash>"` | SHA256 hash in quotes |
+| `Digest` | `sha-256=<base64>` | RFC 3230 format (base64-encoded) |
+| `Content-Length` | Integer | File size in bytes |
+
+### Server-Side Verification on Download
+
+Request server-side verification during download:
+
+```bash
+# Pre-verification: Server verifies before streaming (returns 500 if corrupt)
+curl "${base_url}/api/v1/project/${project}/${package}/+/${tag}?mode=proxy&verify=true&verify_mode=pre"
+
+# Stream verification: Server verifies while streaming (logs error if corrupt)
+curl "${base_url}/api/v1/project/${project}/${package}/+/${tag}?mode=proxy&verify=true&verify_mode=stream"
+```
+
+The `X-Verified` header indicates whether server-side verification was performed:
+- `X-Verified: true` - Content was verified by the server
+
+## Server-Side Consistency Check
+
+### Consistency Check Endpoint
+
+Administrators can run a consistency check to verify all stored artifacts:
+
+```bash
+curl "${base_url}/api/v1/admin/consistency-check"
+```
+
+Response:
+```json
+{
+  "total_artifacts_checked": 1234,
+  "healthy": true,
+  "orphaned_s3_objects": 0,
+  "missing_s3_objects": 0,
+  "size_mismatches": 0,
+  "orphaned_s3_keys": [],
+  "missing_s3_keys": [],
+  "size_mismatch_artifacts": []
+}
+```
+
+### What the Check Verifies
+
+1. **Missing S3 objects**: Database records with no corresponding S3 object
+2. **Orphaned S3 objects**: S3 objects with no database record
+3. **Size mismatches**: S3 object size doesn't match database record
+
+### Running Consistency Checks
+
+**Manual check:**
+```bash
+# Check all artifacts
+curl "${base_url}/api/v1/admin/consistency-check"
+
+# Limit results (for large deployments)
+curl "${base_url}/api/v1/admin/consistency-check?limit=100"
+```
+
+**Scheduled checks (recommended):**
+
+Set up a cron job or Kubernetes CronJob to run periodic checks:
+
+```yaml
+# Kubernetes CronJob example
+apiVersion: batch/v1
+kind: CronJob
+metadata:
+  name: orchard-consistency-check
+spec:
+  schedule: "0 2 * * *"  # Daily at 2 AM
+  jobTemplate:
+    spec:
+      template:
+        spec:
+          containers:
+          - name: check
+            image: curlimages/curl
+            command:
+            - /bin/sh
+            - -c
+            - |
+              response=$(curl -s "${ORCHARD_URL}/api/v1/admin/consistency-check")
+              healthy=$(echo "$response" | jq -r '.healthy')
+              if [ "$healthy" != "true" ]; then
+                echo "ALERT: Consistency check failed!"
+                echo "$response"
+                exit 1
+              fi
+              echo "Consistency check passed"
+          restartPolicy: OnFailure
+```
+
+## Recovery Procedures
+
+### Corrupted Artifact (Size Mismatch)
+
+If the consistency check reports size mismatches:
+
+1. **Identify affected artifacts:**
+   ```bash
+   curl "${base_url}/api/v1/admin/consistency-check" | jq '.size_mismatch_artifacts'
+   ```
+
+2. **Check if artifact can be re-uploaded:**
+   - If the original content is available, delete the corrupted artifact and re-upload
+   - The same content will produce the same artifact ID
+
+3. **If original content is lost:**
+   - The artifact data is corrupted and cannot be recovered
+   - Delete the artifact record and notify affected users
+   - Consider restoring from backup if available
+
+### Missing S3 Object
+
+If database records exist but S3 objects are missing:
+
+1. **Identify affected artifacts:**
+   ```bash
+   curl "${base_url}/api/v1/admin/consistency-check" | jq '.missing_s3_keys'
+   ```
+
+2. **Check S3 bucket:**
+   - Verify the S3 bucket exists and is accessible
+   - Check S3 access logs for deletion events
+   - Check if objects were moved or lifecycle-deleted
+
+3. **Recovery options:**
+   - Restore from S3 versioning (if enabled)
+   - Restore from backup
+   - Re-upload original content (if available)
+   - Delete orphaned database records
+
+### Orphaned S3 Objects
+
+If S3 objects exist without database records:
+
+1. **Identify orphaned objects:**
+   ```bash
+   curl "${base_url}/api/v1/admin/consistency-check" | jq '.orphaned_s3_keys'
+   ```
+
+2. **Investigate cause:**
+   - Upload interrupted before database commit?
+   - Database record deleted but S3 cleanup failed?
+
+3. **Resolution:**
+   - If content is needed, create database record manually
+   - If content is not needed, delete the S3 object to reclaim storage
+
+### Preventive Measures
+
+1. **Enable S3 versioning** to recover from accidental deletions
+2. **Regular backups** of both database and S3 bucket
+3. **Scheduled consistency checks** to detect issues early
+4. **Monitoring and alerting** on consistency check failures
+5. **Audit logging** to track all artifact operations
+
+## Verification in CI/CD
+
+### Verifying Artifacts in Pipelines
+
+```bash
+#!/bin/bash
+# Download and verify artifact in CI pipeline
+
+ARTIFACT_URL="${ORCHARD_URL}/api/v1/project/${PROJECT}/${PACKAGE}/+/${TAG}"
+
+# Download with verification headers
+response=$(curl -s -D - "${ARTIFACT_URL}?mode=proxy" -o artifact.tar.gz)
+expected_hash=$(echo "$response" | grep -i "X-Checksum-SHA256" | cut -d: -f2 | tr -d ' \r')
+
+# Compute actual hash
+actual_hash=$(sha256sum artifact.tar.gz | cut -d' ' -f1)
+
+# Verify
+if [ "$actual_hash" != "$expected_hash" ]; then
+    echo "ERROR: Integrity check failed!"
+    echo "Expected: $expected_hash"
+    echo "Actual:   $actual_hash"
+    exit 1
+fi
+
+echo "Integrity verified: $actual_hash"
+```
+
+### Using Server-Side Verification
+
+For critical deployments, use server-side pre-verification:
+
+```bash
+# Server verifies before streaming - returns 500 if corrupt
+curl -f "${ARTIFACT_URL}?mode=proxy&verify=true&verify_mode=pre" -o artifact.tar.gz
+```
+
+This ensures the artifact is verified before any bytes are streamed to your pipeline.

frontend/src/App.tsx

@@ -10,6 +10,7 @@ import ChangePasswordPage from './pages/ChangePasswordPage';
 import APIKeysPage from './pages/APIKeysPage';
 import AdminUsersPage from './pages/AdminUsersPage';
 import AdminOIDCPage from './pages/AdminOIDCPage';
+import ProjectSettingsPage from './pages/ProjectSettingsPage';
 
 // Component that checks if user must change password
 function RequirePasswordChange({ children }: { children: React.ReactNode }) {
@@ -45,6 +46,7 @@ function AppRoutes() {
                 <Route path="/admin/users" element={<AdminUsersPage />} />
                 <Route path="/admin/oidc" element={<AdminOIDCPage />} />
                 <Route path="/project/:projectName" element={<ProjectPage />} />
+                <Route path="/project/:projectName/settings" element={<ProjectSettingsPage />} />
                 <Route path="/project/:projectName/:packageName" element={<PackagePage />} />
               </Routes>
             </Layout>

frontend/src/api.ts

@@ -32,6 +32,10 @@ import {
   OIDCConfig,
   OIDCConfigUpdate,
   OIDCStatus,
+  PackageVersion,
+  ArtifactDependenciesResponse,
+  ReverseDependenciesResponse,
+  DependencyResolutionResponse,
 } from './types';
 
 const API_BASE = '/api/v1';
@@ -170,6 +174,30 @@ export async function getProject(name: string): Promise<Project> {
   return handleResponse<Project>(response);
 }
 
+export async function updateProject(
+  projectName: string,
+  data: { description?: string; is_public?: boolean }
+): Promise<Project> {
+  const response = await fetch(`${API_BASE}/projects/${projectName}`, {
+    method: 'PUT',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify(data),
+    credentials: 'include',
+  });
+  return handleResponse<Project>(response);
+}
+
+export async function deleteProject(projectName: string): Promise<void> {
+  const response = await fetch(`${API_BASE}/projects/${projectName}`, {
+    method: 'DELETE',
+    credentials: 'include',
+  });
+  if (!response.ok) {
+    const error = await response.json().catch(() => ({ detail: 'Unknown error' }));
+    throw new Error(error.detail || `HTTP ${response.status}`);
+  }
+}
+
 // Package API
 export async function listPackages(projectName: string, params: PackageListParams = {}): Promise<PaginatedResponse<Package>> {
   const query = buildQueryString(params as Record<string, unknown>);
@@ -239,12 +267,21 @@ export async function listPackageArtifacts(
 }
 
 // Upload
-export async function uploadArtifact(projectName: string, packageName: string, file: File, tag?: string): Promise<UploadResponse> {
+export async function uploadArtifact(
+  projectName: string,
+  packageName: string,
+  file: File,
+  tag?: string,
+  version?: string
+): Promise<UploadResponse> {
   const formData = new FormData();
   formData.append('file', file);
   if (tag) {
     formData.append('tag', tag);
   }
+  if (version) {
+    formData.append('version', version);
+  }
 
   const response = await fetch(`${API_BASE}/project/${projectName}/${packageName}/upload`, {
     method: 'POST',
@@ -443,3 +480,85 @@ export function getOIDCLoginUrl(returnTo?: string): string {
   const query = params.toString();
   return `${API_BASE}/auth/oidc/login${query ? `?${query}` : ''}`;
 }
+
+// Version API
+export async function listVersions(
+  projectName: string,
+  packageName: string,
+  params: ListParams = {}
+): Promise<PaginatedResponse<PackageVersion>> {
+  const query = buildQueryString(params as Record<string, unknown>);
+  const response = await fetch(`${API_BASE}/project/${projectName}/${packageName}/versions${query}`);
+  return handleResponse<PaginatedResponse<PackageVersion>>(response);
+}
+
+export async function getVersion(
+  projectName: string,
+  packageName: string,
+  version: string
+): Promise<PackageVersion> {
+  const response = await fetch(`${API_BASE}/project/${projectName}/${packageName}/versions/${version}`);
+  return handleResponse<PackageVersion>(response);
+}
+
+export async function deleteVersion(
+  projectName: string,
+  packageName: string,
+  version: string
+): Promise<void> {
+  const response = await fetch(`${API_BASE}/project/${projectName}/${packageName}/versions/${version}`, {
+    method: 'DELETE',
+    credentials: 'include',
+  });
+  if (!response.ok) {
+    const error = await response.json().catch(() => ({ detail: 'Unknown error' }));
+    throw new Error(error.detail || `HTTP ${response.status}`);
+  }
+}
+
+// Dependency API
+export async function getArtifactDependencies(artifactId: string): Promise<ArtifactDependenciesResponse> {
+  const response = await fetch(`${API_BASE}/artifact/${artifactId}/dependencies`);
+  return handleResponse<ArtifactDependenciesResponse>(response);
+}
+
+export async function getDependenciesByRef(
+  projectName: string,
+  packageName: string,
+  ref: string
+): Promise<ArtifactDependenciesResponse> {
+  const response = await fetch(`${API_BASE}/project/${projectName}/${packageName}/+/${ref}/dependencies`);
+  return handleResponse<ArtifactDependenciesResponse>(response);
+}
+
+export async function getReverseDependencies(
+  projectName: string,
+  packageName: string,
+  params: { page?: number; limit?: number } = {}
+): Promise<ReverseDependenciesResponse> {
+  const query = buildQueryString(params as Record<string, unknown>);
+  const response = await fetch(`${API_BASE}/project/${projectName}/${packageName}/reverse-dependencies${query}`);
+  return handleResponse<ReverseDependenciesResponse>(response);
+}
+
+export async function resolveDependencies(
+  projectName: string,
+  packageName: string,
+  ref: string
+): Promise<DependencyResolutionResponse> {
+  const response = await fetch(`${API_BASE}/project/${projectName}/${packageName}/+/${ref}/resolve`);
+  return handleResponse<DependencyResolutionResponse>(response);
+}
+
+export async function getEnsureFile(
+  projectName: string,
+  packageName: string,
+  ref: string
+): Promise<string> {
+  const response = await fetch(`${API_BASE}/project/${projectName}/${packageName}/+/${ref}/ensure`);
+  if (!response.ok) {
+    const error = await response.json().catch(() => ({ detail: 'Unknown error' }));
+    throw new ApiError(error.detail || `HTTP ${response.status}`, response.status);
+  }
+  return response.text();
+}

frontend/src/components/DependencyGraph.css

@@ -0,0 +1,338 @@
+/* Dependency Graph Modal */
+.dependency-graph-modal {
+  position: fixed;
+  top: 0;
+  left: 0;
+  right: 0;
+  bottom: 0;
+  background: rgba(0, 0, 0, 0.8);
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  z-index: 1000;
+  padding: 24px;
+}
+
+.dependency-graph-content {
+  background: var(--bg-secondary);
+  border: 1px solid var(--border-primary);
+  border-radius: var(--radius-lg);
+  width: 100%;
+  max-width: 1200px;
+  height: 80vh;
+  display: flex;
+  flex-direction: column;
+  overflow: hidden;
+}
+
+.dependency-graph-header {
+  display: flex;
+  align-items: center;
+  gap: 16px;
+  padding: 16px 20px;
+  border-bottom: 1px solid var(--border-primary);
+  background: var(--bg-tertiary);
+}
+
+.dependency-graph-header h2 {
+  margin: 0;
+  font-size: 1.125rem;
+  font-weight: 600;
+  color: var(--text-primary);
+}
+
+.dependency-graph-info {
+  display: flex;
+  align-items: center;
+  gap: 12px;
+  flex: 1;
+  font-size: 0.875rem;
+  color: var(--text-secondary);
+}
+
+.graph-stats {
+  color: var(--text-muted);
+  font-size: 0.8125rem;
+}
+
+.close-btn {
+  background: transparent;
+  border: none;
+  color: var(--text-secondary);
+  cursor: pointer;
+  padding: 4px;
+  border-radius: var(--radius-sm);
+  display: flex;
+  align-items: center;
+  justify-content: center;
+}
+
+.close-btn:hover {
+  background: var(--bg-hover);
+  color: var(--text-primary);
+}
+
+.dependency-graph-toolbar {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  padding: 12px 20px;
+  border-bottom: 1px solid var(--border-primary);
+  background: var(--bg-secondary);
+}
+
+.zoom-level {
+  margin-left: auto;
+  font-size: 0.8125rem;
+  color: var(--text-muted);
+  font-family: 'JetBrains Mono', monospace;
+}
+
+.dependency-graph-container {
+  flex: 1;
+  overflow: hidden;
+  position: relative;
+  background:
+    linear-gradient(90deg, var(--border-primary) 1px, transparent 1px),
+    linear-gradient(var(--border-primary) 1px, transparent 1px);
+  background-size: 20px 20px;
+  background-position: center center;
+}
+
+.graph-canvas {
+  padding: 40px;
+  min-width: 100%;
+  min-height: 100%;
+  transform-origin: center center;
+  transition: transform 0.1s ease-out;
+}
+
+/* Graph Nodes */
+.graph-node-container {
+  display: flex;
+  flex-direction: column;
+  align-items: flex-start;
+}
+
+.graph-node {
+  background: var(--bg-tertiary);
+  border: 2px solid var(--border-primary);
+  border-radius: var(--radius-md);
+  padding: 12px 16px;
+  min-width: 200px;
+  cursor: pointer;
+  transition: all var(--transition-fast);
+  position: relative;
+}
+
+.graph-node:hover {
+  border-color: var(--accent-primary);
+  box-shadow: 0 4px 12px rgba(16, 185, 129, 0.2);
+}
+
+.graph-node--root {
+  background: linear-gradient(135deg, rgba(16, 185, 129, 0.15) 0%, rgba(5, 150, 105, 0.15) 100%);
+  border-color: var(--accent-primary);
+}
+
+.graph-node--hovered {
+  transform: scale(1.02);
+}
+
+.graph-node__header {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  margin-bottom: 4px;
+}
+
+.graph-node__name {
+  font-weight: 600;
+  color: var(--accent-primary);
+  font-family: 'JetBrains Mono', monospace;
+  font-size: 0.875rem;
+}
+
+.graph-node__toggle {
+  background: var(--bg-hover);
+  border: 1px solid var(--border-primary);
+  border-radius: 4px;
+  width: 20px;
+  height: 20px;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  cursor: pointer;
+  font-size: 0.875rem;
+  color: var(--text-secondary);
+  font-weight: 600;
+  margin-left: auto;
+}
+
+.graph-node__toggle:hover {
+  background: var(--bg-tertiary);
+  color: var(--text-primary);
+}
+
+.graph-node__details {
+  display: flex;
+  align-items: center;
+  gap: 12px;
+  font-size: 0.75rem;
+  color: var(--text-muted);
+}
+
+.graph-node__version {
+  font-family: 'JetBrains Mono', monospace;
+  color: var(--text-secondary);
+}
+
+.graph-node__size {
+  color: var(--text-muted);
+}
+
+/* Graph Children / Tree Structure */
+.graph-children {
+  display: flex;
+  padding-left: 24px;
+  margin-top: 8px;
+  position: relative;
+}
+
+.graph-connector {
+  position: absolute;
+  left: 12px;
+  top: 0;
+  bottom: 50%;
+  width: 12px;
+  border-left: 2px solid var(--border-primary);
+  border-bottom: 2px solid var(--border-primary);
+  border-bottom-left-radius: 8px;
+}
+
+.graph-children-list {
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+  position: relative;
+}
+
+.graph-children-list::before {
+  content: '';
+  position: absolute;
+  left: -12px;
+  top: 20px;
+  bottom: 20px;
+  border-left: 2px solid var(--border-primary);
+}
+
+.graph-children-list > .graph-node-container {
+  position: relative;
+}
+
+.graph-children-list > .graph-node-container::before {
+  content: '';
+  position: absolute;
+  left: -12px;
+  top: 20px;
+  width: 12px;
+  border-top: 2px solid var(--border-primary);
+}
+
+/* Loading, Error, Empty States */
+.graph-loading,
+.graph-error,
+.graph-empty {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  height: 100%;
+  gap: 16px;
+  color: var(--text-muted);
+}
+
+.graph-loading .spinner {
+  width: 32px;
+  height: 32px;
+  border: 3px solid var(--border-primary);
+  border-top-color: var(--accent-primary);
+  border-radius: 50%;
+  animation: spin 1s linear infinite;
+}
+
+@keyframes spin {
+  to { transform: rotate(360deg); }
+}
+
+.graph-error {
+  color: var(--error-color, #ef4444);
+}
+
+.graph-error svg {
+  opacity: 0.6;
+}
+
+.graph-error p {
+  max-width: 400px;
+  text-align: center;
+  line-height: 1.5;
+}
+
+/* Tooltip */
+.graph-tooltip {
+  position: fixed;
+  bottom: 24px;
+  left: 50%;
+  transform: translateX(-50%);
+  background: var(--bg-tertiary);
+  border: 1px solid var(--border-primary);
+  border-radius: var(--radius-md);
+  padding: 12px 16px;
+  font-size: 0.8125rem;
+  box-shadow: 0 8px 24px rgba(0, 0, 0, 0.4);
+  z-index: 1001;
+}
+
+.graph-tooltip strong {
+  display: block;
+  color: var(--accent-primary);
+  font-family: 'JetBrains Mono', monospace;
+  margin-bottom: 4px;
+}
+
+.graph-tooltip div {
+  color: var(--text-secondary);
+  margin-top: 2px;
+}
+
+.tooltip-hint {
+  margin-top: 8px;
+  padding-top: 8px;
+  border-top: 1px solid var(--border-primary);
+  color: var(--text-muted);
+  font-size: 0.75rem;
+}
+
+/* Responsive */
+@media (max-width: 768px) {
+  .dependency-graph-modal {
+    padding: 0;
+  }
+
+  .dependency-graph-content {
+    height: 100vh;
+    border-radius: 0;
+    max-width: none;
+  }
+
+  .dependency-graph-header {
+    flex-wrap: wrap;
+  }
+
+  .dependency-graph-info {
+    flex-basis: 100%;
+    order: 3;
+    margin-top: 8px;
+  }
+}

frontend/src/components/DependencyGraph.tsx

@@ -0,0 +1,323 @@
+import { useState, useEffect, useCallback, useRef } from 'react';
+import { useNavigate } from 'react-router-dom';
+import { ResolvedArtifact, DependencyResolutionResponse, Dependency } from '../types';
+import { resolveDependencies, getArtifactDependencies } from '../api';
+import './DependencyGraph.css';
+
+interface DependencyGraphProps {
+  projectName: string;
+  packageName: string;
+  tagName: string;
+  onClose: () => void;
+}
+
+interface GraphNode {
+  id: string;
+  project: string;
+  package: string;
+  version: string | null;
+  size: number;
+  depth: number;
+  children: GraphNode[];
+  isRoot?: boolean;
+}
+
+function formatBytes(bytes: number): string {
+  if (bytes === 0) return '0 B';
+  const k = 1024;
+  const sizes = ['B', 'KB', 'MB', 'GB'];
+  const i = Math.floor(Math.log(bytes) / Math.log(k));
+  return parseFloat((bytes / Math.pow(k, i)).toFixed(1)) + ' ' + sizes[i];
+}
+
+function DependencyGraph({ projectName, packageName, tagName, onClose }: DependencyGraphProps) {
+  const navigate = useNavigate();
+  const containerRef = useRef<HTMLDivElement>(null);
+
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
+  const [resolution, setResolution] = useState<DependencyResolutionResponse | null>(null);
+  const [graphRoot, setGraphRoot] = useState<GraphNode | null>(null);
+  const [hoveredNode, setHoveredNode] = useState<GraphNode | null>(null);
+  const [zoom, setZoom] = useState(1);
+  const [pan, setPan] = useState({ x: 0, y: 0 });
+  const [isDragging, setIsDragging] = useState(false);
+  const [dragStart, setDragStart] = useState({ x: 0, y: 0 });
+  const [collapsedNodes, setCollapsedNodes] = useState<Set<string>>(new Set());
+
+  // Build graph structure from resolution data
+  const buildGraph = useCallback(async (resolutionData: DependencyResolutionResponse) => {
+    const artifactMap = new Map<string, ResolvedArtifact>();
+    resolutionData.resolved.forEach(artifact => {
+      artifactMap.set(artifact.artifact_id, artifact);
+    });
+
+    // Fetch dependencies for each artifact to build the tree
+    const depsMap = new Map<string, Dependency[]>();
+
+    for (const artifact of resolutionData.resolved) {
+      try {
+        const deps = await getArtifactDependencies(artifact.artifact_id);
+        depsMap.set(artifact.artifact_id, deps.dependencies);
+      } catch {
+        depsMap.set(artifact.artifact_id, []);
+      }
+    }
+
+    // Find the root artifact (the requested one)
+    const rootArtifact = resolutionData.resolved.find(
+      a => a.project === resolutionData.requested.project &&
+           a.package === resolutionData.requested.package
+    );
+
+    if (!rootArtifact) {
+      return null;
+    }
+
+    // Build tree recursively
+    const visited = new Set<string>();
+
+    const buildNode = (artifact: ResolvedArtifact, depth: number): GraphNode => {
+      const nodeId = `${artifact.project}/${artifact.package}`;
+      visited.add(artifact.artifact_id);
+
+      const deps = depsMap.get(artifact.artifact_id) || [];
+      const children: GraphNode[] = [];
+
+      for (const dep of deps) {
+        // Find the resolved artifact for this dependency
+        const childArtifact = resolutionData.resolved.find(
+          a => a.project === dep.project && a.package === dep.package
+        );
+
+        if (childArtifact && !visited.has(childArtifact.artifact_id)) {
+          children.push(buildNode(childArtifact, depth + 1));
+        }
+      }
+
+      return {
+        id: nodeId,
+        project: artifact.project,
+        package: artifact.package,
+        version: artifact.version || artifact.tag,
+        size: artifact.size,
+        depth,
+        children,
+        isRoot: depth === 0,
+      };
+    };
+
+    return buildNode(rootArtifact, 0);
+  }, []);
+
+  useEffect(() => {
+    async function loadData() {
+      setLoading(true);
+      setError(null);
+
+      try {
+        const result = await resolveDependencies(projectName, packageName, tagName);
+        setResolution(result);
+
+        const graph = await buildGraph(result);
+        setGraphRoot(graph);
+      } catch (err) {
+        if (err instanceof Error) {
+          // Check if it's a resolution error
+          try {
+            const errorData = JSON.parse(err.message);
+            if (errorData.error === 'circular_dependency') {
+              setError(`Circular dependency detected: ${errorData.cycle?.join(' → ')}`);
+            } else if (errorData.error === 'dependency_conflict') {
+              setError(`Dependency conflict: ${errorData.message}`);
+            } else {
+              setError(err.message);
+            }
+          } catch {
+            setError(err.message);
+          }
+        } else {
+          setError('Failed to load dependency graph');
+        }
+      } finally {
+        setLoading(false);
+      }
+    }
+
+    loadData();
+  }, [projectName, packageName, tagName, buildGraph]);
+
+  const handleNodeClick = (node: GraphNode) => {
+    navigate(`/project/${node.project}/${node.package}`);
+    onClose();
+  };
+
+  const handleNodeToggle = (node: GraphNode, e: React.MouseEvent) => {
+    e.stopPropagation();
+    setCollapsedNodes(prev => {
+      const next = new Set(prev);
+      if (next.has(node.id)) {
+        next.delete(node.id);
+      } else {
+        next.add(node.id);
+      }
+      return next;
+    });
+  };
+
+  const handleWheel = (e: React.WheelEvent) => {
+    e.preventDefault();
+    const delta = e.deltaY > 0 ? -0.1 : 0.1;
+    setZoom(z => Math.max(0.25, Math.min(2, z + delta)));
+  };
+
+  const handleMouseDown = (e: React.MouseEvent) => {
+    if (e.target === containerRef.current || (e.target as HTMLElement).classList.contains('graph-canvas')) {
+      setIsDragging(true);
+      setDragStart({ x: e.clientX - pan.x, y: e.clientY - pan.y });
+    }
+  };
+
+  const handleMouseMove = (e: React.MouseEvent) => {
+    if (isDragging) {
+      setPan({ x: e.clientX - dragStart.x, y: e.clientY - dragStart.y });
+    }
+  };
+
+  const handleMouseUp = () => {
+    setIsDragging(false);
+  };
+
+  const resetView = () => {
+    setZoom(1);
+    setPan({ x: 0, y: 0 });
+  };
+
+  const renderNode = (node: GraphNode, index: number = 0): JSX.Element => {
+    const isCollapsed = collapsedNodes.has(node.id);
+    const hasChildren = node.children.length > 0;
+
+    return (
+      <div key={`${node.id}-${index}`} className="graph-node-container">
+        <div
+          className={`graph-node ${node.isRoot ? 'graph-node--root' : ''} ${hoveredNode?.id === node.id ? 'graph-node--hovered' : ''}`}
+          onClick={() => handleNodeClick(node)}
+          onMouseEnter={() => setHoveredNode(node)}
+          onMouseLeave={() => setHoveredNode(null)}
+        >
+          <div className="graph-node__header">
+            <span className="graph-node__name">{node.project}/{node.package}</span>
+            {hasChildren && (
+              <button
+                className="graph-node__toggle"
+                onClick={(e) => handleNodeToggle(node, e)}
+                title={isCollapsed ? 'Expand' : 'Collapse'}
+              >
+                {isCollapsed ? '+' : '-'}
+              </button>
+            )}
+          </div>
+          <div className="graph-node__details">
+            {node.version && <span className="graph-node__version">@ {node.version}</span>}
+            <span className="graph-node__size">{formatBytes(node.size)}</span>
+          </div>
+        </div>
+
+        {hasChildren && !isCollapsed && (
+          <div className="graph-children">
+            <div className="graph-connector"></div>
+            <div className="graph-children-list">
+              {node.children.map((child, i) => renderNode(child, i))}
+            </div>
+          </div>
+        )}
+      </div>
+    );
+  };
+
+  return (
+    <div className="dependency-graph-modal" onClick={onClose}>
+      <div className="dependency-graph-content" onClick={e => e.stopPropagation()}>
+        <div className="dependency-graph-header">
+          <h2>Dependency Graph</h2>
+          <div className="dependency-graph-info">
+            <span>{projectName}/{packageName} @ {tagName}</span>
+            {resolution && (
+              <span className="graph-stats">
+                {resolution.artifact_count} packages • {formatBytes(resolution.total_size)} total
+              </span>
+            )}
+          </div>
+          <button className="close-btn" onClick={onClose} title="Close">
+            <svg width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2">
+              <line x1="18" y1="6" x2="6" y2="18"></line>
+              <line x1="6" y1="6" x2="18" y2="18"></line>
+            </svg>
+          </button>
+        </div>
+
+        <div className="dependency-graph-toolbar">
+          <button className="btn btn-secondary btn-small" onClick={() => setZoom(z => Math.min(2, z + 0.25))}>
+            Zoom In
+          </button>
+          <button className="btn btn-secondary btn-small" onClick={() => setZoom(z => Math.max(0.25, z - 0.25))}>
+            Zoom Out
+          </button>
+          <button className="btn btn-secondary btn-small" onClick={resetView}>
+            Reset View
+          </button>
+          <span className="zoom-level">{Math.round(zoom * 100)}%</span>
+        </div>
+
+        <div
+          ref={containerRef}
+          className="dependency-graph-container"
+          onWheel={handleWheel}
+          onMouseDown={handleMouseDown}
+          onMouseMove={handleMouseMove}
+          onMouseUp={handleMouseUp}
+          onMouseLeave={handleMouseUp}
+        >
+          {loading ? (
+            <div className="graph-loading">
+              <div className="spinner"></div>
+              <span>Resolving dependencies...</span>
+            </div>
+          ) : error ? (
+            <div className="graph-error">
+              <svg width="48" height="48" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2">
+                <circle cx="12" cy="12" r="10"></circle>
+                <line x1="12" y1="8" x2="12" y2="12"></line>
+                <line x1="12" y1="16" x2="12.01" y2="16"></line>
+              </svg>
+              <p>{error}</p>
+            </div>
+          ) : graphRoot ? (
+            <div
+              className="graph-canvas"
+              style={{
+                transform: `translate(${pan.x}px, ${pan.y}px) scale(${zoom})`,
+                cursor: isDragging ? 'grabbing' : 'grab',
+              }}
+            >
+              {renderNode(graphRoot)}
+            </div>
+          ) : (
+            <div className="graph-empty">No dependencies to display</div>
+          )}
+        </div>
+
+        {hoveredNode && (
+          <div className="graph-tooltip">
+            <strong>{hoveredNode.project}/{hoveredNode.package}</strong>
+            {hoveredNode.version && <div>Version: {hoveredNode.version}</div>}
+            <div>Size: {formatBytes(hoveredNode.size)}</div>
+            <div className="tooltip-hint">Click to navigate</div>
+          </div>
+        )}
+      </div>
+    </div>
+  );
+}
+
+export default DependencyGraph;

frontend/src/components/Layout.tsx

@@ -193,7 +193,6 @@ function Layout({ children }: LayoutProps) {
           </div>
           <div className="footer-links">
             <a href="/docs">Documentation</a>
-            <a href="/api/v1">API</a>
           </div>
         </div>
       </footer>

frontend/src/pages/Home.css

@@ -358,6 +358,12 @@
   gap: 4px;
 }
 
+.page-header__actions {
+  display: flex;
+  align-items: center;
+  gap: 12px;
+}
+
 /* Package card styles */
 .package-card__header {
   display: flex;

frontend/src/pages/PackagePage.css

@@ -127,6 +127,12 @@ h2 {
   font-size: 0.75rem;
 }
 
+/* Action buttons in table */
+.action-buttons {
+  display: flex;
+  gap: 8px;
+}
+
 /* Download by Artifact ID Section */
 .download-by-id-section {
   margin-top: 32px;
@@ -324,6 +330,86 @@ tr:hover .copy-btn {
   color: var(--text-muted);
 }
 
+/* Version badge */
+.version-badge {
+  font-family: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
+  font-size: 0.8125rem;
+  color: var(--accent-primary);
+  background: rgba(16, 185, 129, 0.1);
+  padding: 2px 8px;
+  border-radius: var(--radius-sm);
+}
+
+/* Create Tag Section */
+.create-tag-section {
+  margin-top: 32px;
+  background: var(--bg-secondary);
+}
+
+.create-tag-section h3 {
+  margin-bottom: 4px;
+  color: var(--text-primary);
+  font-size: 1rem;
+  font-weight: 600;
+}
+
+.section-description {
+  color: var(--text-muted);
+  font-size: 0.875rem;
+  margin-bottom: 16px;
+}
+
+.create-tag-form .form-row {
+  display: flex;
+  gap: 12px;
+  align-items: flex-end;
+  flex-wrap: wrap;
+}
+
+.create-tag-form .form-group {
+  flex: 1;
+  min-width: 150px;
+}
+
+.create-tag-form .form-group--wide {
+  flex: 2;
+  min-width: 300px;
+}
+
+.create-tag-form .form-group label {
+  display: block;
+  margin-bottom: 6px;
+  font-size: 0.75rem;
+  font-weight: 500;
+  color: var(--text-secondary);
+  text-transform: uppercase;
+  letter-spacing: 0.05em;
+}
+
+.create-tag-form .form-group input {
+  width: 100%;
+  padding: 10px 14px;
+  background: var(--bg-tertiary);
+  border: 1px solid var(--border-primary);
+  border-radius: var(--radius-md);
+  color: var(--text-primary);
+  font-size: 0.875rem;
+}
+
+.create-tag-form .form-group input:focus {
+  outline: none;
+  border-color: var(--accent-primary);
+}
+
+.create-tag-form .form-group input:disabled {
+  opacity: 0.6;
+  cursor: not-allowed;
+}
+
+.create-tag-form button {
+  flex-shrink: 0;
+}
+
 /* Created cell */
 .created-cell {
   display: flex;
@@ -344,6 +430,340 @@ tr:hover .copy-btn {
   white-space: nowrap;
 }
 
+/* Dependencies Section */
+.dependencies-section {
+  margin-top: 32px;
+  background: var(--bg-secondary);
+}
+
+.dependencies-header {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  margin-bottom: 12px;
+}
+
+.dependencies-header h3 {
+  margin: 0;
+  color: var(--text-primary);
+  font-size: 1rem;
+  font-weight: 600;
+}
+
+.dependencies-controls {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+}
+
+.dependencies-controls .btn {
+  display: inline-flex;
+  align-items: center;
+}
+
+.dependencies-tag-select {
+  margin-bottom: 16px;
+}
+
+.tag-selector {
+  padding: 8px 12px;
+  background: var(--bg-tertiary);
+  border: 1px solid var(--border-primary);
+  border-radius: var(--radius-md);
+  color: var(--text-primary);
+  font-size: 0.875rem;
+  cursor: pointer;
+  min-width: 200px;
+}
+
+.tag-selector:focus {
+  outline: none;
+  border-color: var(--accent-primary);
+}
+
+.deps-loading {
+  color: var(--text-muted);
+  font-size: 0.875rem;
+  padding: 16px 0;
+}
+
+.deps-error {
+  color: var(--error-color, #ef4444);
+  font-size: 0.875rem;
+  padding: 12px 16px;
+  background: rgba(239, 68, 68, 0.1);
+  border-radius: var(--radius-md);
+}
+
+.deps-empty {
+  color: var(--text-muted);
+  font-size: 0.875rem;
+  padding: 16px 0;
+}
+
+.deps-summary {
+  color: var(--text-secondary);
+  font-size: 0.875rem;
+  margin-bottom: 12px;
+}
+
+.deps-summary strong {
+  color: var(--accent-primary);
+}
+
+.deps-items {
+  list-style: none;
+  margin: 0;
+  padding: 0;
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+}
+
+.dep-item {
+  display: flex;
+  align-items: center;
+  gap: 12px;
+  padding: 12px 16px;
+  background: var(--bg-tertiary);
+  border-radius: var(--radius-md);
+  border: 1px solid var(--border-primary);
+}
+
+.dep-link {
+  color: var(--accent-primary);
+  font-weight: 500;
+  text-decoration: none;
+  font-family: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
+  font-size: 0.875rem;
+}
+
+.dep-link:hover {
+  text-decoration: underline;
+}
+
+.dep-constraint {
+  color: var(--text-muted);
+  font-size: 0.8125rem;
+  font-family: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
+}
+
+.dep-status {
+  margin-left: auto;
+  font-size: 0.875rem;
+  font-weight: 600;
+}
+
+.dep-status--ok {
+  color: var(--success-color, #10b981);
+}
+
+.dep-status--missing {
+  color: var(--warning-color, #f59e0b);
+}
+
+/* Tag name link in table */
+.tag-name-link {
+  color: var(--accent-primary);
+  transition: opacity var(--transition-fast);
+}
+
+.tag-name-link:hover {
+  opacity: 0.8;
+}
+
+.tag-name-link.selected {
+  text-decoration: underline;
+}
+
+/* Used By (Reverse Dependencies) Section */
+.used-by-section {
+  margin-top: 32px;
+  background: var(--bg-secondary);
+}
+
+.used-by-section h3 {
+  margin-bottom: 16px;
+  color: var(--text-primary);
+  font-size: 1rem;
+  font-weight: 600;
+}
+
+.reverse-dep-item {
+  display: flex;
+  align-items: center;
+  gap: 12px;
+  flex-wrap: wrap;
+}
+
+.dep-version {
+  color: var(--accent-primary);
+  font-family: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
+  font-size: 0.8125rem;
+  background: rgba(16, 185, 129, 0.1);
+  padding: 2px 8px;
+  border-radius: var(--radius-sm);
+}
+
+.dep-requires {
+  color: var(--text-muted);
+  font-size: 0.8125rem;
+  font-family: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
+  margin-left: auto;
+}
+
+.reverse-deps-pagination {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: 16px;
+  margin-top: 16px;
+  padding-top: 16px;
+  border-top: 1px solid var(--border-primary);
+}
+
+.pagination-info {
+  color: var(--text-secondary);
+  font-size: 0.875rem;
+}
+
+/* Ensure File Modal */
+.modal-overlay {
+  position: fixed;
+  top: 0;
+  left: 0;
+  right: 0;
+  bottom: 0;
+  background: rgba(0, 0, 0, 0.7);
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  z-index: 1000;
+  padding: 20px;
+}
+
+.ensure-file-modal {
+  background: var(--bg-secondary);
+  border: 1px solid var(--border-primary);
+  border-radius: var(--radius-lg);
+  max-width: 700px;
+  width: 100%;
+  max-height: 80vh;
+  display: flex;
+  flex-direction: column;
+  box-shadow: 0 20px 50px rgba(0, 0, 0, 0.5);
+}
+
+.ensure-file-header {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  padding: 16px 20px;
+  border-bottom: 1px solid var(--border-primary);
+}
+
+.ensure-file-header h3 {
+  margin: 0;
+  color: var(--text-primary);
+  font-size: 1rem;
+  font-weight: 600;
+}
+
+.ensure-file-actions {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+}
+
+.ensure-file-actions .copy-btn {
+  opacity: 1;
+  width: 32px;
+  height: 32px;
+}
+
+.modal-close {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  width: 32px;
+  height: 32px;
+  padding: 0;
+  background: transparent;
+  border: none;
+  border-radius: var(--radius-sm);
+  color: var(--text-muted);
+  cursor: pointer;
+  transition: all var(--transition-fast);
+}
+
+.modal-close:hover {
+  background: var(--bg-hover);
+  color: var(--text-primary);
+}
+
+.ensure-file-content {
+  flex: 1;
+  overflow: auto;
+  padding: 20px;
+}
+
+.ensure-file-loading {
+  color: var(--text-muted);
+  text-align: center;
+  padding: 40px 20px;
+}
+
+.ensure-file-error {
+  color: var(--error-color, #ef4444);
+  padding: 16px;
+  background: rgba(239, 68, 68, 0.1);
+  border-radius: var(--radius-md);
+}
+
+.ensure-file-empty {
+  color: var(--text-muted);
+  text-align: center;
+  padding: 40px 20px;
+  font-style: italic;
+}
+
+.ensure-file-yaml {
+  margin: 0;
+  padding: 16px;
+  background: #0d0d0f;
+  border: 1px solid var(--border-primary);
+  border-radius: var(--radius-md);
+  overflow-x: auto;
+}
+
+.ensure-file-yaml code {
+  font-family: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
+  font-size: 0.8125rem;
+  color: #e2e8f0;
+  white-space: pre;
+}
+
+.ensure-file-footer {
+  padding: 16px 20px;
+  border-top: 1px solid var(--border-primary);
+  background: var(--bg-tertiary);
+  border-radius: 0 0 var(--radius-lg) var(--radius-lg);
+}
+
+.ensure-file-hint {
+  margin: 0;
+  color: var(--text-muted);
+  font-size: 0.8125rem;
+}
+
+.ensure-file-hint code {
+  background: rgba(0, 0, 0, 0.2);
+  padding: 2px 6px;
+  border-radius: var(--radius-sm);
+  font-family: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
+  color: var(--accent-primary);
+}
+
 /* Responsive adjustments */
 @media (max-width: 768px) {
   .upload-form {
@@ -359,4 +779,18 @@ tr:hover .copy-btn {
     flex-wrap: wrap;
     gap: 12px;
   }
+
+  .dependencies-header {
+    flex-direction: column;
+    align-items: flex-start;
+    gap: 12px;
+  }
+
+  .tag-selector {
+    width: 100%;
+  }
+
+  .ensure-file-modal {
+    max-height: 90vh;
+  }
 }

frontend/src/pages/PackagePage.tsx

@@ -1,7 +1,7 @@
 import { useState, useEffect, useCallback } from 'react';
-import { useParams, useSearchParams, useNavigate, useLocation } from 'react-router-dom';
-import { TagDetail, Package, PaginatedResponse, AccessLevel } from '../types';
-import { listTags, getDownloadUrl, getPackage, getMyProjectAccess, UnauthorizedError, ForbiddenError } from '../api';
+import { useParams, useSearchParams, useNavigate, useLocation, Link } from 'react-router-dom';
+import { TagDetail, Package, PaginatedResponse, AccessLevel, Dependency, DependentInfo } from '../types';
+import { listTags, getDownloadUrl, getPackage, getMyProjectAccess, createTag, getArtifactDependencies, getReverseDependencies, getEnsureFile, UnauthorizedError, ForbiddenError } from '../api';
 import { Breadcrumb } from '../components/Breadcrumb';
 import { Badge } from '../components/Badge';
 import { SearchInput } from '../components/SearchInput';
@@ -10,6 +10,7 @@ import { DataTable } from '../components/DataTable';
 import { Pagination } from '../components/Pagination';
 import { DragDropUpload, UploadResult } from '../components/DragDropUpload';
 import { useAuth } from '../contexts/AuthContext';
+import DependencyGraph from '../components/DependencyGraph';
 import './Home.css';
 import './PackagePage.css';
 
@@ -64,6 +65,33 @@ function PackagePage() {
   const [uploadSuccess, setUploadSuccess] = useState<string | null>(null);
   const [artifactIdInput, setArtifactIdInput] = useState('');
   const [accessLevel, setAccessLevel] = useState<AccessLevel | null>(null);
+  const [createTagName, setCreateTagName] = useState('');
+  const [createTagArtifactId, setCreateTagArtifactId] = useState('');
+  const [createTagLoading, setCreateTagLoading] = useState(false);
+
+  // Dependencies state
+  const [selectedTag, setSelectedTag] = useState<TagDetail | null>(null);
+  const [dependencies, setDependencies] = useState<Dependency[]>([]);
+  const [depsLoading, setDepsLoading] = useState(false);
+  const [depsError, setDepsError] = useState<string | null>(null);
+
+  // Reverse dependencies state
+  const [reverseDeps, setReverseDeps] = useState<DependentInfo[]>([]);
+  const [reverseDepsLoading, setReverseDepsLoading] = useState(false);
+  const [reverseDepsError, setReverseDepsError] = useState<string | null>(null);
+  const [reverseDepsPage, setReverseDepsPage] = useState(1);
+  const [reverseDepsTotal, setReverseDepsTotal] = useState(0);
+  const [reverseDepsHasMore, setReverseDepsHasMore] = useState(false);
+
+  // Dependency graph modal state
+  const [showGraph, setShowGraph] = useState(false);
+
+  // Ensure file modal state
+  const [showEnsureFile, setShowEnsureFile] = useState(false);
+  const [ensureFileContent, setEnsureFileContent] = useState<string | null>(null);
+  const [ensureFileLoading, setEnsureFileLoading] = useState(false);
+  const [ensureFileError, setEnsureFileError] = useState<string | null>(null);
+  const [ensureFileTagName, setEnsureFileTagName] = useState<string | null>(null);
 
   // Derived permissions
   const canWrite = accessLevel === 'write' || accessLevel === 'admin';
@@ -125,6 +153,98 @@ function PackagePage() {
     loadData();
   }, [loadData]);
 
+  // Auto-select tag when tags are loaded (prefer version from URL, then first tag)
+  // Re-run when package changes to pick up new tags
+  useEffect(() => {
+    if (tagsData?.items && tagsData.items.length > 0) {
+      const versionParam = searchParams.get('version');
+      if (versionParam) {
+        // Find tag matching the version parameter
+        const matchingTag = tagsData.items.find(t => t.version === versionParam);
+        if (matchingTag) {
+          setSelectedTag(matchingTag);
+          setDependencies([]);
+          return;
+        }
+      }
+      // Fall back to first tag
+      setSelectedTag(tagsData.items[0]);
+      setDependencies([]);
+    }
+  }, [tagsData, searchParams, projectName, packageName]);
+
+  // Fetch dependencies when selected tag changes
+  const fetchDependencies = useCallback(async (artifactId: string) => {
+    setDepsLoading(true);
+    setDepsError(null);
+    try {
+      const result = await getArtifactDependencies(artifactId);
+      setDependencies(result.dependencies);
+    } catch (err) {
+      setDepsError(err instanceof Error ? err.message : 'Failed to load dependencies');
+      setDependencies([]);
+    } finally {
+      setDepsLoading(false);
+    }
+  }, []);
+
+  useEffect(() => {
+    if (selectedTag) {
+      fetchDependencies(selectedTag.artifact_id);
+    }
+  }, [selectedTag, fetchDependencies]);
+
+  // Fetch reverse dependencies
+  const fetchReverseDeps = useCallback(async (pageNum: number = 1) => {
+    if (!projectName || !packageName) return;
+
+    setReverseDepsLoading(true);
+    setReverseDepsError(null);
+    try {
+      const result = await getReverseDependencies(projectName, packageName, { page: pageNum, limit: 10 });
+      setReverseDeps(result.dependents);
+      setReverseDepsTotal(result.pagination.total);
+      setReverseDepsHasMore(result.pagination.has_more);
+      setReverseDepsPage(pageNum);
+    } catch (err) {
+      setReverseDepsError(err instanceof Error ? err.message : 'Failed to load reverse dependencies');
+      setReverseDeps([]);
+    } finally {
+      setReverseDepsLoading(false);
+    }
+  }, [projectName, packageName]);
+
+  useEffect(() => {
+    if (projectName && packageName && !loading) {
+      fetchReverseDeps(1);
+    }
+  }, [projectName, packageName, loading, fetchReverseDeps]);
+
+  // Fetch ensure file for a specific tag
+  const fetchEnsureFileForTag = useCallback(async (tagName: string) => {
+    if (!projectName || !packageName) return;
+
+    setEnsureFileTagName(tagName);
+    setEnsureFileLoading(true);
+    setEnsureFileError(null);
+    try {
+      const content = await getEnsureFile(projectName, packageName, tagName);
+      setEnsureFileContent(content);
+      setShowEnsureFile(true);
+    } catch (err) {
+      setEnsureFileError(err instanceof Error ? err.message : 'Failed to load ensure file');
+      setShowEnsureFile(true);
+    } finally {
+      setEnsureFileLoading(false);
+    }
+  }, [projectName, packageName]);
+
+  // Fetch ensure file for selected tag
+  const fetchEnsureFile = useCallback(async () => {
+    if (!selectedTag) return;
+    fetchEnsureFileForTag(selectedTag.name);
+  }, [selectedTag, fetchEnsureFileForTag]);
+
   // Keyboard navigation - go back with backspace
   useEffect(() => {
     const handleKeyDown = (e: KeyboardEvent) => {
@@ -154,6 +274,30 @@ function PackagePage() {
     setError(errorMsg);
   }, []);
 
+  const handleCreateTag = async (e: React.FormEvent) => {
+    e.preventDefault();
+    if (!createTagName.trim() || createTagArtifactId.length !== 64) return;
+
+    setCreateTagLoading(true);
+    setError(null);
+
+    try {
+      await createTag(projectName!, packageName!, {
+        name: createTagName.trim(),
+        artifact_id: createTagArtifactId,
+      });
+      setUploadSuccess(`Tag "${createTagName}" created successfully!`);
+      setCreateTagName('');
+      setCreateTagArtifactId('');
+      loadData();
+      setTimeout(() => setUploadSuccess(null), 5000);
+    } catch (err) {
+      setError(err instanceof Error ? err.message : 'Failed to create tag');
+    } finally {
+      setCreateTagLoading(false);
+    }
+  };
+
   const handleSearchChange = (value: string) => {
     updateParams({ search: value, page: '1' });
   };
@@ -175,12 +319,31 @@ function PackagePage() {
   const tags = tagsData?.items || [];
   const pagination = tagsData?.pagination;
 
+  const handleTagSelect = (tag: TagDetail) => {
+    setSelectedTag(tag);
+  };
+
   const columns = [
     {
       key: 'name',
       header: 'Tag',
       sortable: true,
-      render: (t: TagDetail) => <strong>{t.name}</strong>,
+      render: (t: TagDetail) => (
+        <strong
+          className={`tag-name-link ${selectedTag?.id === t.id ? 'selected' : ''}`}
+          onClick={() => handleTagSelect(t)}
+          style={{ cursor: 'pointer' }}
+        >
+          {t.name}
+        </strong>
+      ),
+    },
+    {
+      key: 'version',
+      header: 'Version',
+      render: (t: TagDetail) => (
+        <span className="version-badge">{t.version || '-'}</span>
+      ),
     },
     {
       key: 'artifact_id',
@@ -227,13 +390,22 @@ function PackagePage() {
       key: 'actions',
       header: 'Actions',
       render: (t: TagDetail) => (
-        <a
-          href={getDownloadUrl(projectName!, packageName!, t.name)}
-          className="btn btn-secondary btn-small"
-          download
-        >
-          Download
-        </a>
+        <div className="action-buttons">
+          <button
+            className="btn btn-secondary btn-small"
+            onClick={() => fetchEnsureFileForTag(t.name)}
+            title="View orchard.ensure file"
+          >
+            Ensure
+          </button>
+          <a
+            href={getDownloadUrl(projectName!, packageName!, t.name)}
+            className="btn btn-secondary btn-small"
+            download
+          >
+            Download
+          </a>
+        </div>
       ),
     },
   ];
@@ -405,6 +577,166 @@ function PackagePage() {
         />
       )}
 
+      {/* Dependencies Section */}
+      {tags.length > 0 && (
+        <div className="dependencies-section card">
+          <div className="dependencies-header">
+            <h3>Dependencies</h3>
+            <div className="dependencies-controls">
+              {selectedTag && (
+                <>
+                  <button
+                    className="btn btn-secondary btn-small"
+                    onClick={fetchEnsureFile}
+                    disabled={ensureFileLoading}
+                    title="View orchard.ensure file"
+                  >
+                    <svg width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" style={{ marginRight: '6px' }}>
+                      <path d="M14 2H6a2 2 0 0 0-2 2v16a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2V8z"></path>
+                      <polyline points="14 2 14 8 20 8"></polyline>
+                      <line x1="16" y1="13" x2="8" y2="13"></line>
+                      <line x1="16" y1="17" x2="8" y2="17"></line>
+                      <polyline points="10 9 9 9 8 9"></polyline>
+                    </svg>
+                    {ensureFileLoading ? 'Loading...' : 'View Ensure File'}
+                  </button>
+                  <button
+                    className="btn btn-secondary btn-small"
+                    onClick={() => setShowGraph(true)}
+                    title="View full dependency tree"
+                  >
+                    <svg width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" style={{ marginRight: '6px' }}>
+                      <circle cx="12" cy="12" r="3"></circle>
+                      <circle cx="4" cy="4" r="2"></circle>
+                      <circle cx="20" cy="4" r="2"></circle>
+                      <circle cx="4" cy="20" r="2"></circle>
+                      <circle cx="20" cy="20" r="2"></circle>
+                      <line x1="9.5" y1="9.5" x2="5.5" y2="5.5"></line>
+                      <line x1="14.5" y1="9.5" x2="18.5" y2="5.5"></line>
+                      <line x1="9.5" y1="14.5" x2="5.5" y2="18.5"></line>
+                      <line x1="14.5" y1="14.5" x2="18.5" y2="18.5"></line>
+                    </svg>
+                    View Graph
+                  </button>
+                </>
+              )}
+            </div>
+          </div>
+          <div className="dependencies-tag-select">
+            {selectedTag && (
+              <select
+                className="tag-selector"
+                value={selectedTag.id}
+                onChange={(e) => {
+                  const tag = tags.find(t => t.id === e.target.value);
+                  if (tag) setSelectedTag(tag);
+                }}
+              >
+                {tags.map(t => (
+                  <option key={t.id} value={t.id}>
+                    {t.name}{t.version ? ` (${t.version})` : ''}
+                  </option>
+                ))}
+              </select>
+            )}
+          </div>
+
+          {depsLoading ? (
+            <div className="deps-loading">Loading dependencies...</div>
+          ) : depsError ? (
+            <div className="deps-error">{depsError}</div>
+          ) : dependencies.length === 0 ? (
+            <div className="deps-empty">
+              {selectedTag ? (
+                <span><strong>{selectedTag.name}</strong> has no dependencies</span>
+              ) : (
+                <span>No dependencies</span>
+              )}
+            </div>
+          ) : (
+            <div className="deps-list">
+              <div className="deps-summary">
+                <strong>{selectedTag?.name}</strong> has {dependencies.length} {dependencies.length === 1 ? 'dependency' : 'dependencies'}:
+              </div>
+              <ul className="deps-items">
+                {dependencies.map((dep) => (
+                  <li key={dep.id} className="dep-item">
+                    <Link
+                      to={`/project/${dep.project}/${dep.package}`}
+                      className="dep-link"
+                    >
+                      {dep.project}/{dep.package}
+                    </Link>
+                    <span className="dep-constraint">
+                      @ {dep.version || dep.tag}
+                    </span>
+                    <span className="dep-status dep-status--ok" title="Package exists">
+                      &#10003;
+                    </span>
+                  </li>
+                ))}
+              </ul>
+            </div>
+          )}
+        </div>
+      )}
+
+      {/* Used By (Reverse Dependencies) Section */}
+      <div className="used-by-section card">
+        <h3>Used By</h3>
+
+        {reverseDepsLoading ? (
+          <div className="deps-loading">Loading reverse dependencies...</div>
+        ) : reverseDepsError ? (
+          <div className="deps-error">{reverseDepsError}</div>
+        ) : reverseDeps.length === 0 ? (
+          <div className="deps-empty">No packages depend on this package</div>
+        ) : (
+          <div className="reverse-deps-list">
+            <div className="deps-summary">
+              {reverseDepsTotal} {reverseDepsTotal === 1 ? 'package depends' : 'packages depend'} on this:
+            </div>
+            <ul className="deps-items">
+              {reverseDeps.map((dep) => (
+                <li key={dep.artifact_id} className="dep-item reverse-dep-item">
+                  <Link
+                    to={`/project/${dep.project}/${dep.package}${dep.version ? `?version=${dep.version}` : ''}`}
+                    className="dep-link"
+                  >
+                    {dep.project}/{dep.package}
+                    {dep.version && (
+                      <span className="dep-version">v{dep.version}</span>
+                    )}
+                  </Link>
+                  <span className="dep-requires">
+                    requires @ {dep.constraint_value}
+                  </span>
+                </li>
+              ))}
+            </ul>
+            {(reverseDepsHasMore || reverseDepsPage > 1) && (
+              <div className="reverse-deps-pagination">
+                <button
+                  className="btn btn-secondary btn-small"
+                  onClick={() => fetchReverseDeps(reverseDepsPage - 1)}
+                  disabled={reverseDepsPage <= 1 || reverseDepsLoading}
+                >
+                  Previous
+                </button>
+                <span className="pagination-info">Page {reverseDepsPage}</span>
+                <button
+                  className="btn btn-secondary btn-small"
+                  onClick={() => fetchReverseDeps(reverseDepsPage + 1)}
+                  disabled={!reverseDepsHasMore || reverseDepsLoading}
+                >
+                  Next
+                </button>
+              </div>
+            )}
+          </div>
+        )}
+      </div>
+
       <div className="download-by-id-section card">
         <h3>Download by Artifact ID</h3>
         <div className="download-by-id-form">
@@ -433,6 +765,50 @@ function PackagePage() {
         )}
       </div>
 
+      {user && canWrite && (
+        <div className="create-tag-section card">
+          <h3>Create / Update Tag</h3>
+          <p className="section-description">Point a tag at any existing artifact by its ID</p>
+          <form onSubmit={handleCreateTag} className="create-tag-form">
+            <div className="form-row">
+              <div className="form-group">
+                <label htmlFor="create-tag-name">Tag Name</label>
+                <input
+                  id="create-tag-name"
+                  type="text"
+                  value={createTagName}
+                  onChange={(e) => setCreateTagName(e.target.value)}
+                  placeholder="latest, stable, v1.0.0..."
+                  disabled={createTagLoading}
+                />
+              </div>
+              <div className="form-group form-group--wide">
+                <label htmlFor="create-tag-artifact">Artifact ID</label>
+                <input
+                  id="create-tag-artifact"
+                  type="text"
+                  value={createTagArtifactId}
+                  onChange={(e) => setCreateTagArtifactId(e.target.value.toLowerCase().replace(/[^a-f0-9]/g, '').slice(0, 64))}
+                  placeholder="SHA256 hash (64 hex characters)"
+                  className="artifact-id-input"
+                  disabled={createTagLoading}
+                />
+              </div>
+              <button
+                type="submit"
+                className="btn btn-primary"
+                disabled={createTagLoading || !createTagName.trim() || createTagArtifactId.length !== 64}
+              >
+                {createTagLoading ? 'Creating...' : 'Create Tag'}
+              </button>
+            </div>
+            {createTagArtifactId.length > 0 && createTagArtifactId.length !== 64 && (
+              <p className="validation-hint">Artifact ID must be exactly 64 hex characters ({createTagArtifactId.length}/64)</p>
+            )}
+          </form>
+        </div>
+      )}
+
       <div className="usage-section card">
         <h3>Usage</h3>
         <p>Download artifacts using:</p>
@@ -444,6 +820,58 @@ function PackagePage() {
           <code>curl -O {window.location.origin}/api/v1/project/{projectName}/{packageName}/+/v1.0.0</code>
         </pre>
       </div>
+
+      {/* Dependency Graph Modal */}
+      {showGraph && selectedTag && (
+        <DependencyGraph
+          projectName={projectName!}
+          packageName={packageName!}
+          tagName={selectedTag.name}
+          onClose={() => setShowGraph(false)}
+        />
+      )}
+
+      {/* Ensure File Modal */}
+      {showEnsureFile && (
+        <div className="modal-overlay" onClick={() => setShowEnsureFile(false)}>
+          <div className="ensure-file-modal" onClick={(e) => e.stopPropagation()}>
+            <div className="ensure-file-header">
+              <h3>orchard.ensure for {ensureFileTagName}</h3>
+              <div className="ensure-file-actions">
+                {ensureFileContent && (
+                  <CopyButton text={ensureFileContent} />
+                )}
+                <button
+                  className="modal-close"
+                  onClick={() => setShowEnsureFile(false)}
+                  title="Close"
+                >
+                  <svg width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2">
+                    <line x1="18" y1="6" x2="6" y2="18"></line>
+                    <line x1="6" y1="6" x2="18" y2="18"></line>
+                  </svg>
+                </button>
+              </div>
+            </div>
+            <div className="ensure-file-content">
+              {ensureFileLoading ? (
+                <div className="ensure-file-loading">Loading...</div>
+              ) : ensureFileError ? (
+                <div className="ensure-file-error">{ensureFileError}</div>
+              ) : ensureFileContent ? (
+                <pre className="ensure-file-yaml"><code>{ensureFileContent}</code></pre>
+              ) : (
+                <div className="ensure-file-empty">No dependencies defined for this artifact.</div>
+              )}
+            </div>
+            <div className="ensure-file-footer">
+              <p className="ensure-file-hint">
+                Save this as <code>orchard.ensure</code> in your project root to declare dependencies.
+              </p>
+            </div>
+          </div>
+        </div>
+      )}
     </div>
   );
 }

frontend/src/pages/ProjectPage.tsx

@@ -8,7 +8,6 @@ import { DataTable } from '../components/DataTable';
 import { SearchInput } from '../components/SearchInput';
 import { FilterChip, FilterChipGroup } from '../components/FilterChip';
 import { Pagination } from '../components/Pagination';
-import { AccessManagement } from '../components/AccessManagement';
 import { useAuth } from '../contexts/AuthContext';
 import './Home.css';
 
@@ -211,15 +210,30 @@ function ProjectPage() {
             <span className="meta-item">by {project.created_by}</span>
           </div>
         </div>
-        {canWrite ? (
-          <button className="btn btn-primary" onClick={() => setShowForm(!showForm)}>
-            {showForm ? 'Cancel' : '+ New Package'}
-          </button>
-        ) : user ? (
-          <span className="text-muted" title="You have read-only access to this project">
-            Read-only access
-          </span>
-        ) : null}
+        <div className="page-header__actions">
+          {canAdmin && (
+            <button
+              className="btn btn-secondary"
+              onClick={() => navigate(`/project/${projectName}/settings`)}
+              title="Project Settings"
+            >
+              <svg width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round">
+                <circle cx="12" cy="12" r="3" />
+                <path d="M19.4 15a1.65 1.65 0 0 0 .33 1.82l.06.06a2 2 0 0 1 0 2.83 2 2 0 0 1-2.83 0l-.06-.06a1.65 1.65 0 0 0-1.82-.33 1.65 1.65 0 0 0-1 1.51V21a2 2 0 0 1-2 2 2 2 0 0 1-2-2v-.09A1.65 1.65 0 0 0 9 19.4a1.65 1.65 0 0 0-1.82.33l-.06.06a2 2 0 0 1-2.83 0 2 2 0 0 1 0-2.83l.06-.06a1.65 1.65 0 0 0 .33-1.82 1.65 1.65 0 0 0-1.51-1H3a2 2 0 0 1-2-2 2 2 0 0 1 2-2h.09A1.65 1.65 0 0 0 4.6 9a1.65 1.65 0 0 0-.33-1.82l-.06-.06a2 2 0 0 1 0-2.83 2 2 0 0 1 2.83 0l.06.06a1.65 1.65 0 0 0 1.82.33H9a1.65 1.65 0 0 0 1-1.51V3a2 2 0 0 1 2-2 2 2 0 0 1 2 2v.09a1.65 1.65 0 0 0 1 1.51 1.65 1.65 0 0 0 1.82-.33l.06-.06a2 2 0 0 1 2.83 0 2 2 0 0 1 0 2.83l-.06.06a1.65 1.65 0 0 0-.33 1.82V9a1.65 1.65 0 0 0 1.51 1H21a2 2 0 0 1 2 2 2 2 0 0 1-2 2h-.09a1.65 1.65 0 0 0-1.51 1z" />
+              </svg>
+              Settings
+            </button>
+          )}
+          {canWrite ? (
+            <button className="btn btn-primary" onClick={() => setShowForm(!showForm)}>
+              {showForm ? 'Cancel' : '+ New Package'}
+            </button>
+          ) : user ? (
+            <span className="text-muted" title="You have read-only access to this project">
+              Read-only access
+            </span>
+          ) : null}
+        </div>
       </div>
 
       {error && <div className="error-message">{error}</div>}
@@ -371,10 +385,6 @@ function ProjectPage() {
           onPageChange={handlePageChange}
         />
       )}
-
-      {canAdmin && projectName && (
-        <AccessManagement projectName={projectName} />
-      )}
     </div>
   );
 }

frontend/src/pages/ProjectSettingsPage.css

@@ -0,0 +1,476 @@
+.project-settings-page {
+  max-width: 900px;
+  margin: 0 auto;
+}
+
+.project-settings-header {
+  margin-bottom: 32px;
+}
+
+.project-settings-header h1 {
+  font-size: 1.75rem;
+  font-weight: 600;
+  color: var(--text-primary);
+  margin-bottom: 8px;
+  letter-spacing: -0.02em;
+}
+
+.project-settings-subtitle {
+  color: var(--text-tertiary);
+  font-size: 0.9375rem;
+}
+
+.project-settings-loading {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: 12px;
+  padding: 64px 24px;
+  color: var(--text-tertiary);
+  font-size: 0.9375rem;
+}
+
+.project-settings-spinner {
+  width: 20px;
+  height: 20px;
+  border: 2px solid var(--border-secondary);
+  border-top-color: var(--accent-primary);
+  border-radius: 50%;
+  animation: project-settings-spin 0.6s linear infinite;
+}
+
+@keyframes project-settings-spin {
+  to {
+    transform: rotate(360deg);
+  }
+}
+
+.project-settings-error {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  background: var(--error-bg);
+  border: 1px solid rgba(239, 68, 68, 0.2);
+  color: var(--error);
+  padding: 12px 16px;
+  border-radius: var(--radius-md);
+  margin-bottom: 24px;
+  font-size: 0.875rem;
+}
+
+.project-settings-success {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  background: var(--success-bg);
+  border: 1px solid rgba(34, 197, 94, 0.2);
+  color: var(--success);
+  padding: 12px 16px;
+  border-radius: var(--radius-md);
+  margin-bottom: 24px;
+  font-size: 0.875rem;
+  animation: project-settings-fade-in 0.2s ease;
+}
+
+@keyframes project-settings-fade-in {
+  from {
+    opacity: 0;
+    transform: translateY(-8px);
+  }
+  to {
+    opacity: 1;
+    transform: translateY(0);
+  }
+}
+
+.project-settings-section {
+  background: var(--bg-secondary);
+  border: 1px solid var(--border-primary);
+  border-radius: var(--radius-lg);
+  padding: 24px;
+  margin-bottom: 24px;
+}
+
+.project-settings-section h2 {
+  font-size: 1.125rem;
+  font-weight: 600;
+  color: var(--text-primary);
+  margin-bottom: 20px;
+  padding-bottom: 16px;
+  border-bottom: 1px solid var(--border-primary);
+}
+
+.project-settings-form {
+  display: flex;
+  flex-direction: column;
+  gap: 16px;
+}
+
+.project-settings-form-group {
+  display: flex;
+  flex-direction: column;
+  gap: 6px;
+}
+
+.project-settings-form-group label {
+  font-size: 0.8125rem;
+  font-weight: 500;
+  color: var(--text-secondary);
+}
+
+.project-settings-form-group textarea,
+.project-settings-form-group input[type="text"] {
+  padding: 12px 14px;
+  background: var(--bg-tertiary);
+  border: 1px solid var(--border-primary);
+  border-radius: var(--radius-md);
+  font-size: 0.875rem;
+  color: var(--text-primary);
+  transition: all var(--transition-fast);
+  font-family: inherit;
+  resize: vertical;
+}
+
+.project-settings-form-group textarea {
+  min-height: 100px;
+}
+
+.project-settings-form-group textarea::placeholder,
+.project-settings-form-group input::placeholder {
+  color: var(--text-muted);
+}
+
+.project-settings-form-group textarea:hover:not(:disabled),
+.project-settings-form-group input:hover:not(:disabled) {
+  border-color: var(--border-secondary);
+  background: var(--bg-elevated);
+}
+
+.project-settings-form-group textarea:focus,
+.project-settings-form-group input:focus {
+  outline: none;
+  border-color: var(--accent-primary);
+  box-shadow: 0 0 0 3px rgba(16, 185, 129, 0.15);
+  background: var(--bg-elevated);
+}
+
+.project-settings-form-group textarea:disabled,
+.project-settings-form-group input:disabled {
+  opacity: 0.6;
+  cursor: not-allowed;
+}
+
+.project-settings-checkbox-group {
+  flex-direction: row;
+  align-items: center;
+}
+
+.project-settings-checkbox-label {
+  display: flex;
+  align-items: center;
+  gap: 10px;
+  cursor: pointer;
+  font-size: 0.875rem;
+  font-weight: 400;
+  color: var(--text-secondary);
+  user-select: none;
+}
+
+.project-settings-checkbox-label input[type="checkbox"] {
+  position: absolute;
+  opacity: 0;
+  width: 0;
+  height: 0;
+}
+
+.project-settings-checkbox-custom {
+  width: 18px;
+  height: 18px;
+  background: var(--bg-tertiary);
+  border: 1px solid var(--border-secondary);
+  border-radius: var(--radius-sm);
+  transition: all var(--transition-fast);
+  position: relative;
+  flex-shrink: 0;
+}
+
+.project-settings-checkbox-label input[type="checkbox"]:checked + .project-settings-checkbox-custom {
+  background: var(--accent-primary);
+  border-color: var(--accent-primary);
+}
+
+.project-settings-checkbox-label input[type="checkbox"]:checked + .project-settings-checkbox-custom::after {
+  content: '';
+  position: absolute;
+  left: 5px;
+  top: 2px;
+  width: 5px;
+  height: 9px;
+  border: solid white;
+  border-width: 0 2px 2px 0;
+  transform: rotate(45deg);
+}
+
+.project-settings-checkbox-label input[type="checkbox"]:focus + .project-settings-checkbox-custom {
+  box-shadow: 0 0 0 3px rgba(16, 185, 129, 0.15);
+}
+
+.project-settings-checkbox-label:hover .project-settings-checkbox-custom {
+  border-color: var(--accent-primary);
+}
+
+.project-settings-form-actions {
+  display: flex;
+  justify-content: flex-end;
+  gap: 12px;
+  margin-top: 8px;
+}
+
+.project-settings-save-button {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: 8px;
+  padding: 10px 18px;
+  background: var(--accent-gradient);
+  border: none;
+  border-radius: var(--radius-md);
+  font-size: 0.875rem;
+  font-weight: 500;
+  color: white;
+  cursor: pointer;
+  transition: all var(--transition-fast);
+  min-width: 120px;
+}
+
+.project-settings-save-button:hover:not(:disabled) {
+  transform: translateY(-1px);
+  box-shadow: var(--shadow-sm), 0 0 20px rgba(16, 185, 129, 0.2);
+}
+
+.project-settings-save-button:disabled {
+  opacity: 0.5;
+  cursor: not-allowed;
+  transform: none;
+}
+
+.project-settings-button-spinner {
+  width: 14px;
+  height: 14px;
+  border: 2px solid rgba(255, 255, 255, 0.3);
+  border-top-color: white;
+  border-radius: 50%;
+  animation: project-settings-spin 0.6s linear infinite;
+}
+
+/* Danger Zone */
+.project-settings-danger-zone {
+  background: var(--bg-secondary);
+  border: 1px solid rgba(239, 68, 68, 0.3);
+  border-radius: var(--radius-lg);
+  padding: 24px;
+  margin-bottom: 24px;
+}
+
+.project-settings-danger-zone h2 {
+  font-size: 1.125rem;
+  font-weight: 600;
+  color: var(--error);
+  margin-bottom: 20px;
+  padding-bottom: 16px;
+  border-bottom: 1px solid rgba(239, 68, 68, 0.2);
+}
+
+.project-settings-danger-item {
+  display: flex;
+  justify-content: space-between;
+  align-items: flex-start;
+  gap: 24px;
+}
+
+.project-settings-danger-info h3 {
+  font-size: 0.9375rem;
+  font-weight: 600;
+  color: var(--text-primary);
+  margin-bottom: 4px;
+}
+
+.project-settings-danger-info p {
+  color: var(--text-tertiary);
+  font-size: 0.8125rem;
+  max-width: 400px;
+}
+
+.project-settings-delete-button {
+  padding: 10px 18px;
+  background: transparent;
+  border: 1px solid rgba(239, 68, 68, 0.3);
+  border-radius: var(--radius-md);
+  font-size: 0.875rem;
+  font-weight: 500;
+  color: var(--error);
+  cursor: pointer;
+  transition: all var(--transition-fast);
+  flex-shrink: 0;
+}
+
+.project-settings-delete-button:hover:not(:disabled) {
+  background: var(--error-bg);
+  border-color: rgba(239, 68, 68, 0.5);
+}
+
+.project-settings-delete-button:disabled {
+  opacity: 0.5;
+  cursor: not-allowed;
+}
+
+/* Delete Confirmation */
+.project-settings-delete-confirm {
+  margin-top: 20px;
+  padding-top: 20px;
+  border-top: 1px solid rgba(239, 68, 68, 0.2);
+  animation: project-settings-fade-in 0.2s ease;
+}
+
+.project-settings-delete-confirm p {
+  color: var(--text-secondary);
+  font-size: 0.875rem;
+  margin-bottom: 12px;
+}
+
+.project-settings-delete-confirm strong {
+  color: var(--text-primary);
+  font-family: 'JetBrains Mono', 'Fira Code', 'SF Mono', Monaco, monospace;
+  background: var(--bg-tertiary);
+  padding: 2px 6px;
+  border-radius: var(--radius-sm);
+}
+
+.project-settings-delete-confirm-input {
+  width: 100%;
+  padding: 12px 14px;
+  background: var(--bg-tertiary);
+  border: 1px solid var(--border-primary);
+  border-radius: var(--radius-md);
+  font-size: 0.875rem;
+  color: var(--text-primary);
+  transition: all var(--transition-fast);
+  margin-bottom: 16px;
+}
+
+.project-settings-delete-confirm-input:focus {
+  outline: none;
+  border-color: var(--error);
+  box-shadow: 0 0 0 3px rgba(239, 68, 68, 0.15);
+}
+
+.project-settings-delete-confirm-input::placeholder {
+  color: var(--text-muted);
+}
+
+.project-settings-delete-confirm-actions {
+  display: flex;
+  gap: 12px;
+}
+
+.project-settings-confirm-delete-button {
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  gap: 8px;
+  padding: 10px 18px;
+  background: var(--error);
+  border: none;
+  border-radius: var(--radius-md);
+  font-size: 0.875rem;
+  font-weight: 500;
+  color: white;
+  cursor: pointer;
+  transition: all var(--transition-fast);
+  min-width: 120px;
+}
+
+.project-settings-confirm-delete-button:hover:not(:disabled) {
+  opacity: 0.9;
+}
+
+.project-settings-confirm-delete-button:disabled {
+  opacity: 0.5;
+  cursor: not-allowed;
+}
+
+.project-settings-cancel-button {
+  padding: 10px 18px;
+  background: transparent;
+  border: 1px solid var(--border-primary);
+  border-radius: var(--radius-md);
+  font-size: 0.875rem;
+  font-weight: 500;
+  color: var(--text-secondary);
+  cursor: pointer;
+  transition: all var(--transition-fast);
+}
+
+.project-settings-cancel-button:hover:not(:disabled) {
+  background: var(--bg-hover);
+  border-color: var(--border-secondary);
+  color: var(--text-primary);
+}
+
+.project-settings-cancel-button:disabled {
+  opacity: 0.5;
+  cursor: not-allowed;
+}
+
+.project-settings-delete-spinner {
+  width: 14px;
+  height: 14px;
+  border: 2px solid rgba(255, 255, 255, 0.3);
+  border-top-color: white;
+  border-radius: 50%;
+  animation: project-settings-spin 0.6s linear infinite;
+}
+
+/* Access denied */
+.project-settings-access-denied {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  justify-content: center;
+  padding: 80px 24px;
+  text-align: center;
+}
+
+.project-settings-access-denied h2 {
+  font-size: 1.5rem;
+  font-weight: 600;
+  color: var(--text-primary);
+  margin-bottom: 12px;
+}
+
+.project-settings-access-denied p {
+  color: var(--text-tertiary);
+  font-size: 0.9375rem;
+  max-width: 400px;
+}
+
+/* Responsive */
+@media (max-width: 768px) {
+  .project-settings-danger-item {
+    flex-direction: column;
+    gap: 16px;
+  }
+
+  .project-settings-delete-button {
+    align-self: flex-start;
+  }
+
+  .project-settings-delete-confirm-actions {
+    flex-direction: column;
+  }
+
+  .project-settings-confirm-delete-button,
+  .project-settings-cancel-button {
+    width: 100%;
+  }
+}

frontend/src/pages/ProjectSettingsPage.tsx

@@ -0,0 +1,308 @@
+import { useState, useEffect, useCallback } from 'react';
+import { useParams, useNavigate } from 'react-router-dom';
+import { Project } from '../types';
+import {
+  getProject,
+  updateProject,
+  deleteProject,
+  getMyProjectAccess,
+  UnauthorizedError,
+  ForbiddenError,
+} from '../api';
+import { Breadcrumb } from '../components/Breadcrumb';
+import { AccessManagement } from '../components/AccessManagement';
+import { useAuth } from '../contexts/AuthContext';
+import './ProjectSettingsPage.css';
+
+function ProjectSettingsPage() {
+  const { projectName } = useParams<{ projectName: string }>();
+  const navigate = useNavigate();
+  const { user } = useAuth();
+
+  const [project, setProject] = useState<Project | null>(null);
+  const [loading, setLoading] = useState(true);
+  const [error, setError] = useState<string | null>(null);
+  const [success, setSuccess] = useState<string | null>(null);
+  const [accessDenied, setAccessDenied] = useState(false);
+  const [canAdmin, setCanAdmin] = useState(false);
+
+  // General settings form state
+  const [description, setDescription] = useState('');
+  const [isPublic, setIsPublic] = useState(false);
+  const [saving, setSaving] = useState(false);
+
+  // Delete confirmation state
+  const [showDeleteConfirm, setShowDeleteConfirm] = useState(false);
+  const [deleteConfirmText, setDeleteConfirmText] = useState('');
+  const [deleting, setDeleting] = useState(false);
+
+  const loadData = useCallback(async () => {
+    if (!projectName) return;
+
+    try {
+      setLoading(true);
+      setAccessDenied(false);
+      const [projectData, accessResult] = await Promise.all([
+        getProject(projectName),
+        getMyProjectAccess(projectName),
+      ]);
+      setProject(projectData);
+      setDescription(projectData.description || '');
+      setIsPublic(projectData.is_public);
+
+      const hasAdminAccess = accessResult.access_level === 'admin';
+      setCanAdmin(hasAdminAccess);
+
+      if (!hasAdminAccess) {
+        setAccessDenied(true);
+      }
+
+      setError(null);
+    } catch (err) {
+      if (err instanceof UnauthorizedError) {
+        navigate('/login', { state: { from: `/project/${projectName}/settings` } });
+        return;
+      }
+      if (err instanceof ForbiddenError) {
+        setAccessDenied(true);
+        setLoading(false);
+        return;
+      }
+      setError(err instanceof Error ? err.message : 'Failed to load project');
+    } finally {
+      setLoading(false);
+    }
+  }, [projectName, navigate]);
+
+  useEffect(() => {
+    loadData();
+  }, [loadData]);
+
+  const handleSaveSettings = async (e: React.FormEvent) => {
+    e.preventDefault();
+    if (!projectName) return;
+
+    try {
+      setSaving(true);
+      setError(null);
+      const updatedProject = await updateProject(projectName, {
+        description: description || undefined,
+        is_public: isPublic,
+      });
+      setProject(updatedProject);
+      setSuccess('Settings saved successfully');
+      setTimeout(() => setSuccess(null), 3000);
+    } catch (err) {
+      setError(err instanceof Error ? err.message : 'Failed to save settings');
+    } finally {
+      setSaving(false);
+    }
+  };
+
+  const handleDeleteProject = async () => {
+    if (!projectName || deleteConfirmText !== projectName) return;
+
+    try {
+      setDeleting(true);
+      setError(null);
+      await deleteProject(projectName);
+      navigate('/');
+    } catch (err) {
+      setError(err instanceof Error ? err.message : 'Failed to delete project');
+      setDeleting(false);
+    }
+  };
+
+  const handleCancelDelete = () => {
+    setShowDeleteConfirm(false);
+    setDeleteConfirmText('');
+  };
+
+  if (loading) {
+    return (
+      <div className="project-settings-page">
+        <Breadcrumb
+          items={[
+            { label: 'Projects', href: '/' },
+            { label: projectName || '', href: `/project/${projectName}` },
+            { label: 'Settings' },
+          ]}
+        />
+        <div className="project-settings-loading">
+          <div className="project-settings-spinner" />
+          <span>Loading...</span>
+        </div>
+      </div>
+    );
+  }
+
+  if (accessDenied || !canAdmin) {
+    return (
+      <div className="project-settings-page">
+        <Breadcrumb
+          items={[
+            { label: 'Projects', href: '/' },
+            { label: projectName || '', href: `/project/${projectName}` },
+            { label: 'Settings' },
+          ]}
+        />
+        <div className="project-settings-access-denied">
+          <h2>Access Denied</h2>
+          <p>You must be a project admin to access settings.</p>
+          {!user && (
+            <p style={{ marginTop: '16px' }}>
+              <a href="/login" className="btn btn-primary">
+                Sign in
+              </a>
+            </p>
+          )}
+        </div>
+      </div>
+    );
+  }
+
+  if (!project) {
+    return (
+      <div className="project-settings-page">
+        <Breadcrumb
+          items={[
+            { label: 'Projects', href: '/' },
+            { label: projectName || '' },
+          ]}
+        />
+        <div className="project-settings-error">Project not found</div>
+      </div>
+    );
+  }
+
+  return (
+    <div className="project-settings-page">
+      <Breadcrumb
+        items={[
+          { label: 'Projects', href: '/' },
+          { label: project.name, href: `/project/${project.name}` },
+          { label: 'Settings' },
+        ]}
+      />
+
+      <div className="project-settings-header">
+        <h1>Project Settings</h1>
+        <p className="project-settings-subtitle">Manage settings for {project.name}</p>
+      </div>
+
+      {error && <div className="project-settings-error">{error}</div>}
+      {success && <div className="project-settings-success">{success}</div>}
+
+      {/* General Settings Section */}
+      <div className="project-settings-section">
+        <h2>General</h2>
+        <form className="project-settings-form" onSubmit={handleSaveSettings}>
+          <div className="project-settings-form-group">
+            <label htmlFor="description">Description</label>
+            <textarea
+              id="description"
+              value={description}
+              onChange={(e) => setDescription(e.target.value)}
+              placeholder="Describe your project..."
+              disabled={saving}
+            />
+          </div>
+
+          <div className="project-settings-form-group project-settings-checkbox-group">
+            <label className="project-settings-checkbox-label">
+              <input
+                type="checkbox"
+                checked={isPublic}
+                onChange={(e) => setIsPublic(e.target.checked)}
+                disabled={saving}
+              />
+              <span className="project-settings-checkbox-custom" />
+              <span>Public project (visible to everyone)</span>
+            </label>
+          </div>
+
+          <div className="project-settings-form-actions">
+            <button type="submit" className="project-settings-save-button" disabled={saving}>
+              {saving ? (
+                <>
+                  <span className="project-settings-button-spinner" />
+                  Saving...
+                </>
+              ) : (
+                'Save Changes'
+              )}
+            </button>
+          </div>
+        </form>
+      </div>
+
+      {/* Access Management Section */}
+      <AccessManagement projectName={projectName!} />
+
+      {/* Danger Zone Section */}
+      <div className="project-settings-danger-zone">
+        <h2>Danger Zone</h2>
+        <div className="project-settings-danger-item">
+          <div className="project-settings-danger-info">
+            <h3>Delete this project</h3>
+            <p>
+              Once you delete a project, there is no going back. This will permanently delete the
+              project, all packages, artifacts, and tags.
+            </p>
+          </div>
+          {!showDeleteConfirm && (
+            <button
+              className="project-settings-delete-button"
+              onClick={() => setShowDeleteConfirm(true)}
+              disabled={deleting}
+            >
+              Delete Project
+            </button>
+          )}
+        </div>
+
+        {showDeleteConfirm && (
+          <div className="project-settings-delete-confirm">
+            <p>
+              Type <strong>{project.name}</strong> to confirm deletion:
+            </p>
+            <input
+              type="text"
+              className="project-settings-delete-confirm-input"
+              value={deleteConfirmText}
+              onChange={(e) => setDeleteConfirmText(e.target.value)}
+              placeholder={project.name}
+              disabled={deleting}
+              autoFocus
+            />
+            <div className="project-settings-delete-confirm-actions">
+              <button
+                className="project-settings-confirm-delete-button"
+                onClick={handleDeleteProject}
+                disabled={deleting || deleteConfirmText !== project.name}
+              >
+                {deleting ? (
+                  <>
+                    <span className="project-settings-delete-spinner" />
+                    Deleting...
+                  </>
+                ) : (
+                  'Yes, delete this project'
+                )}
+              </button>
+              <button
+                className="project-settings-cancel-button"
+                onClick={handleCancelDelete}
+                disabled={deleting}
+              >
+                Cancel
+              </button>
+            </div>
+          </div>
+        )}
+      </div>
+    </div>
+  );
+}
+
+export default ProjectSettingsPage;

frontend/src/types.ts

@@ -63,6 +63,22 @@ export interface TagDetail extends Tag {
   artifact_original_name: string | null;
   artifact_created_at: string;
   artifact_format_metadata: Record<string, unknown> | null;
+  version: string | null;
+}
+
+export interface PackageVersion {
+  id: string;
+  package_id: string;
+  artifact_id: string;
+  version: string;
+  version_source: string | null;
+  created_at: string;
+  created_by: string;
+  // Enriched fields from joins
+  size?: number;
+  content_type?: string | null;
+  original_name?: string | null;
+  tags?: string[];
 }
 
 export interface ArtifactTagInfo {
@@ -122,6 +138,8 @@ export interface UploadResponse {
   project: string;
   package: string;
   tag: string | null;
+  version: string | null;
+  version_source: string | null;
 }
 
 // Global search types
@@ -355,3 +373,77 @@ export interface OIDCStatus {
   enabled: boolean;
   issuer_url?: string;
 }
+
+// Dependency types
+export interface Dependency {
+  id: string;
+  artifact_id: string;
+  project: string;
+  package: string;
+  version: string | null;
+  tag: string | null;
+  created_at: string;
+}
+
+export interface ArtifactDependenciesResponse {
+  artifact_id: string;
+  dependencies: Dependency[];
+}
+
+export interface DependentInfo {
+  artifact_id: string;
+  project: string;
+  package: string;
+  version: string | null;
+  constraint_type: 'version' | 'tag';
+  constraint_value: string;
+}
+
+export interface ReverseDependenciesResponse {
+  project: string;
+  package: string;
+  dependents: DependentInfo[];
+  pagination: {
+    page: number;
+    limit: number;
+    total: number;
+    total_pages: number;
+    has_more: boolean;
+  };
+}
+
+// Dependency Resolution types
+export interface ResolvedArtifact {
+  artifact_id: string;
+  project: string;
+  package: string;
+  version: string | null;
+  tag: string | null;
+  size: number;
+  download_url: string;
+}
+
+export interface DependencyResolutionResponse {
+  requested: {
+    project: string;
+    package: string;
+    ref: string;
+  };
+  resolved: ResolvedArtifact[];
+  total_size: number;
+  artifact_count: number;
+}
+
+export interface DependencyResolutionError {
+  error: 'circular_dependency' | 'dependency_conflict' | 'not_found';
+  message: string;
+  cycle?: string[];
+  conflicts?: Array<{
+    project: string;
+    package: string;
+    requirements: Array<{
+      version: string;
+      required_by: Array<{ path: string }>;
+    }>;
+  }>;
+}

helm/orchard/templates/_helpers.tpl

@@ -77,6 +77,8 @@ PostgreSQL secret name
 {{- define "orchard.postgresql.secretName" -}}
 {{- if .Values.orchard.database.existingSecret }}
 {{- .Values.orchard.database.existingSecret }}
+{{- else if and .Values.orchard.database.secretsManager .Values.orchard.database.secretsManager.enabled }}
+{{- printf "%s-db-credentials" (include "orchard.fullname" .) }}
 {{- else if .Values.postgresql.enabled }}
 {{- printf "%s-postgresql" .Release.Name }}
 {{- else }}
@@ -90,6 +92,8 @@ PostgreSQL password key in secret
 {{- define "orchard.postgresql.passwordKey" -}}
 {{- if .Values.orchard.database.existingSecret -}}
 {{- .Values.orchard.database.existingSecretPasswordKey -}}
+{{- else if and .Values.orchard.database.secretsManager .Values.orchard.database.secretsManager.enabled -}}
+password
 {{- else if .Values.postgresql.enabled -}}
 password
 {{- else -}}

helm/orchard/templates/deployment.yaml

@@ -69,6 +69,8 @@ spec:
               containerPort: {{ .Values.orchard.server.port }}
               protocol: TCP
           env:
+            - name: ORCHARD_ENV
+              value: {{ .Values.orchard.env | default "development" | quote }}
             - name: ORCHARD_SERVER_HOST
               value: {{ .Values.orchard.server.host | quote }}
             - name: ORCHARD_SERVER_PORT
@@ -77,8 +79,16 @@ spec:
               value: {{ include "orchard.postgresql.host" . | quote }}
             - name: ORCHARD_DATABASE_PORT
               value: {{ .Values.orchard.database.port | quote }}
+            {{- if and .Values.orchard.database.secretsManager .Values.orchard.database.secretsManager.enabled }}
+            - name: ORCHARD_DATABASE_USER
+              valueFrom:
+                secretKeyRef:
+                  name: {{ include "orchard.postgresql.secretName" . }}
+                  key: username
+            {{- else }}
             - name: ORCHARD_DATABASE_USER
               value: {{ .Values.orchard.database.user | default .Values.postgresql.auth.username | quote }}
+            {{- end }}
             - name: ORCHARD_DATABASE_DBNAME
               value: {{ .Values.orchard.database.dbname | default .Values.postgresql.auth.database | quote }}
             - name: ORCHARD_DATABASE_SSLMODE
@@ -96,6 +106,7 @@ spec:
               value: {{ .Values.orchard.s3.bucket | quote }}
             - name: ORCHARD_S3_USE_PATH_STYLE
               value: {{ .Values.orchard.s3.usePathStyle | quote }}
+            {{- if or .Values.minio.enabled .Values.orchard.s3.existingSecret .Values.orchard.s3.accessKeyId }}
             - name: ORCHARD_S3_ACCESS_KEY_ID
               valueFrom:
                 secretKeyRef:
@@ -106,16 +117,38 @@ spec:
                 secretKeyRef:
                   name: {{ include "orchard.minio.secretName" . }}
                   key: {{ if .Values.minio.enabled }}root-password{{ else }}{{ .Values.orchard.s3.existingSecretSecretKeyKey }}{{ end }}
+            {{- end }}
             - name: ORCHARD_DOWNLOAD_MODE
               value: {{ .Values.orchard.download.mode | quote }}
             - name: ORCHARD_PRESIGNED_URL_EXPIRY
               value: {{ .Values.orchard.download.presignedUrlExpiry | quote }}
+            {{- if .Values.orchard.rateLimit }}
+            {{- if .Values.orchard.rateLimit.login }}
+            - name: ORCHARD_LOGIN_RATE_LIMIT
+              value: {{ .Values.orchard.rateLimit.login | quote }}
+            {{- end }}
+            {{- end }}
+          {{- if and .Values.orchard.database.secretsManager .Values.orchard.database.secretsManager.enabled }}
+          volumeMounts:
+            - name: db-secrets
+              mountPath: /mnt/secrets-store
+              readOnly: true
+          {{- end }}
           livenessProbe:
             {{- toYaml .Values.livenessProbe | nindent 12 }}
           readinessProbe:
             {{- toYaml .Values.readinessProbe | nindent 12 }}
           resources:
             {{- toYaml .Values.resources | nindent 12 }}
+      {{- if and .Values.orchard.database.secretsManager .Values.orchard.database.secretsManager.enabled }}
+      volumes:
+        - name: db-secrets
+          csi:
+            driver: secrets-store.csi.k8s.io
+            readOnly: true
+            volumeAttributes:
+              secretProviderClass: {{ include "orchard.fullname" . }}-db-secret
+      {{- end }}
       {{- with .Values.nodeSelector }}
       nodeSelector:
         {{- toYaml . | nindent 8 }}

helm/orchard/templates/secret-provider-class.yaml

@@ -0,0 +1,27 @@
+{{- if and .Values.orchard.database.secretsManager .Values.orchard.database.secretsManager.enabled }}
+apiVersion: secrets-store.csi.x-k8s.io/v1
+kind: SecretProviderClass
+metadata:
+  name: {{ include "orchard.fullname" . }}-db-secret
+  labels:
+    {{- include "orchard.labels" . | nindent 4 }}
+spec:
+  provider: aws
+  parameters:
+    objects: |
+      - objectName: "{{ .Values.orchard.database.secretsManager.secretArn }}"
+        objectType: "secretsmanager"
+        jmesPath:
+          - path: username
+            objectAlias: db-username
+          - path: password
+            objectAlias: db-password
+  secretObjects:
+    - secretName: {{ include "orchard.fullname" . }}-db-credentials
+      type: Opaque
+      data:
+        - objectName: db-username
+          key: username
+        - objectName: db-password
+          key: password
+{{- end }}

helm/orchard/values-dev.yaml

@@ -42,6 +42,7 @@ ingress:
   className: "nginx"
   annotations:
     cert-manager.io/cluster-issuer: "letsencrypt"
+    nginx.ingress.kubernetes.io/proxy-body-size: "0"  # Disable body size limit for uploads
   hosts:
     - host: orchard-dev.common.global.bsf.tools  # Overridden by CI
       paths:
@@ -84,6 +85,7 @@ tolerations: []
 affinity: {}
 
 orchard:
+  env: "development"  # Allows seed data for testing
   server:
     host: "0.0.0.0"
     port: 8080
@@ -113,6 +115,10 @@ orchard:
     mode: "presigned"
     presignedUrlExpiry: 3600
 
+  # Relaxed rate limits for dev/feature environments (allows integration tests to run)
+  rateLimit:
+    login: "1000/minute"  # Default is 5/minute, relaxed for CI integration tests
+
 # PostgreSQL - ephemeral, no persistence
 postgresql:
   enabled: true

helm/orchard/values-prod.yaml

@@ -0,0 +1,136 @@
+# Production values for orchard
+# TODO: Replace subcharts with managed services (RDS, S3) when ready
+replicaCount: 1
+
+image:
+  repository: registry.global.bsf.tools/esv/bsf/bsf-integration/orchard/orchard-mvp
+  pullPolicy: Always
+  tag: "latest"  # Overridden by CI
+
+imagePullSecrets:
+  - name: orchard-pull-secret
+
+initContainer:
+  image:
+    repository: containers.global.bsf.tools/busybox
+    tag: "1.36"
+    pullPolicy: IfNotPresent
+
+serviceAccount:
+  create: true
+  automount: true
+  annotations:
+    eks.amazonaws.com/role-arn: arn:aws-us-gov:iam::052673043337:role/service-orchard-prd
+  name: "orchard"
+
+podAnnotations: {}
+podLabels: {}
+
+podSecurityContext: {}
+
+securityContext:
+  readOnlyRootFilesystem: false
+  runAsNonRoot: true
+  runAsUser: 1000
+
+service:
+  type: ClusterIP
+  port: 8080
+
+ingress:
+  enabled: true
+  className: "nginx"
+  annotations:
+    cert-manager.io/cluster-issuer: "letsencrypt"
+    nginx.ingress.kubernetes.io/proxy-body-size: "0"  # Disable body size limit for uploads
+  hosts:
+    - host: orchard.common.global.bsf.tools
+      paths:
+        - path: /
+          pathType: Prefix
+  tls:
+    - secretName: orchard-prod-tls
+      hosts:
+        - orchard.common.global.bsf.tools
+
+# Production resources - same as stage for MVP, increase as needed
+resources:
+  limits:
+    cpu: 500m
+    memory: 512Mi
+  requests:
+    cpu: 500m
+    memory: 512Mi
+
+livenessProbe:
+  httpGet:
+    path: /health
+    port: http
+  initialDelaySeconds: 10
+  periodSeconds: 10
+
+readinessProbe:
+  httpGet:
+    path: /health
+    port: http
+  initialDelaySeconds: 5
+  periodSeconds: 5
+
+autoscaling:
+  enabled: false
+  minReplicas: 1
+  maxReplicas: 10
+  targetCPUUtilizationPercentage: 80
+  targetMemoryUtilizationPercentage: 80
+
+nodeSelector: {}
+tolerations: []
+affinity: {}
+
+orchard:
+  env: "production"  # Disables seed data
+  server:
+    host: "0.0.0.0"
+    port: 8080
+
+  # Database configuration - uses AWS Secrets Manager via CSI driver
+  database:
+    host: "orchard-prd.cluster-cvw3jzjkozoc.us-gov-west-1.rds.amazonaws.com"
+    port: 5432
+    dbname: orchard_prod
+    sslmode: require
+    secretsManager:
+      enabled: true
+      secretArn: "arn:aws-us-gov:secretsmanager:us-gov-west-1:052673043337:secret:rds!cluster-0afc8af5-f644-4284-92fb-2ed545490f92-3v9uXV"
+
+  # S3 configuration - uses IRSA for credentials
+  s3:
+    endpoint: ""  # Empty = use AWS default
+    region: us-gov-west-1
+    bucket: orchard-artifacts-prod
+    usePathStyle: false  # Real S3 uses virtual-hosted style
+
+  download:
+    mode: "presigned"
+    presignedUrlExpiry: 3600
+
+# PostgreSQL subchart - disabled in prod, using RDS
+postgresql:
+  enabled: false
+
+# MinIO subchart - disabled in prod, using real S3
+minio:
+  enabled: false
+
+# MinIO ingress - disabled in prod, using real S3
+minioIngress:
+  enabled: false
+
+redis:
+  enabled: false
+
+waitForDatabase: true
+
+global:
+  security:
+    allowInsecureImages: true

helm/orchard/values-stage.yaml

@@ -19,7 +19,8 @@ initContainer:
 serviceAccount:
   create: true
   automount: true
-  annotations: {}
+  annotations:
+    eks.amazonaws.com/role-arn: arn:aws-us-gov:iam::052673043337:role/service-orchard-stage
   name: "orchard"
 
 podAnnotations: {}
@@ -41,6 +42,7 @@ ingress:
   className: "nginx"
   annotations:
     cert-manager.io/cluster-issuer: "letsencrypt"
+    nginx.ingress.kubernetes.io/proxy-body-size: "0"  # Disable body size limit for uploads
   hosts:
     - host: orchard-stage.common.global.bsf.tools
       paths:
@@ -88,130 +90,48 @@ affinity: {}
 
 # Orchard server configuration
 orchard:
+  env: "development"  # Allows seed data for testing
   server:
     host: "0.0.0.0"
     port: 8080
 
-  # Database configuration (used when postgresql.enabled is false)
+  # Database configuration - uses AWS Secrets Manager via CSI driver
   database:
-    host: ""
+    host: "orchard-stage.cluster-cvw3jzjkozoc.us-gov-west-1.rds.amazonaws.com"
     port: 5432
-    user: orchard
-    password: ""
-    dbname: orchard
-    sslmode: disable
-    existingSecret: ""
-    existingSecretPasswordKey: "password"
+    dbname: postgres
+    sslmode: require
+    secretsManager:
+      enabled: true
+      secretArn: "arn:aws-us-gov:secretsmanager:us-gov-west-1:052673043337:secret:rds!cluster-a573672b-1a38-4665-a654-1b7df37b5297-IaeFQL"
 
-  # S3 configuration (used when minio.enabled is false)
+  # S3 configuration - uses IRSA for credentials
   s3:
-    endpoint: ""
-    region: us-east-1
-    bucket: orchard-artifacts
-    accessKeyId: ""
-    secretAccessKey: ""
-    usePathStyle: true
-    existingSecret: ""
-    existingSecretAccessKeyKey: "access-key-id"
-    existingSecretSecretKeyKey: "secret-access-key"
+    endpoint: ""  # Empty = use AWS default
+    region: us-gov-west-1
+    bucket: orchard-artifacts-stage
+    usePathStyle: false  # Real S3 uses virtual-hosted style
 
   # Download configuration
   download:
     mode: "presigned"  # presigned, redirect, or proxy
     presignedUrlExpiry: 3600  # Presigned URL expiry in seconds
 
-# PostgreSQL subchart configuration
+  # Relaxed rate limits for stage (allows CI integration tests to run)
+  rateLimit:
+    login: "1000/minute"  # Default is 5/minute, relaxed for CI integration tests
+
+# PostgreSQL subchart - disabled in stage, using RDS
 postgresql:
-  enabled: true
-  image:
-    registry: containers.global.bsf.tools
-    repository: bitnami/postgresql
-    tag: "15"
-    pullPolicy: IfNotPresent
-  auth:
-    username: orchard
-    password: orchard-password
-    database: orchard
-  primary:
-    persistence:
-      enabled: false
-      size: 10Gi
-    # Resources with memory requests = limits per cluster policy
-    resourcesPreset: "none"
-    resources:
-      limits:
-        cpu: 500m
-        memory: 512Mi
-      requests:
-        cpu: 250m
-        memory: 512Mi
-  # Volume permissions init container
-  volumePermissions:
-    resourcesPreset: "none"
-    resources:
-      limits:
-        cpu: 100m
-        memory: 128Mi
-      requests:
-        cpu: 50m
-        memory: 128Mi
+  enabled: false
 
-# MinIO subchart configuration
+# MinIO subchart - disabled in stage, using real S3
 minio:
-  enabled: true
-  image:
-    registry: containers.global.bsf.tools
-    repository: bitnami/minio
-    tag: "latest"
-    pullPolicy: IfNotPresent
-  auth:
-    rootUser: minioadmin
-    rootPassword: minioadmin
-  defaultBuckets: "orchard-artifacts"
-  persistence:
-    enabled: false
-    size: 50Gi
-  # Resources with memory requests = limits per cluster policy
-  resourcesPreset: "none"  # Disable preset to use explicit resources
-  resources:
-    limits:
-      cpu: 500m
-      memory: 512Mi
-    requests:
-      cpu: 250m
-      memory: 512Mi
-  # Init container resources
-  defaultInitContainers:
-    volumePermissions:
-      resourcesPreset: "none"
-      resources:
-        limits:
-          cpu: 100m
-          memory: 128Mi
-        requests:
-          cpu: 50m
-          memory: 128Mi
-  # Provisioning job resources
-  provisioning:
-    resources:
-      limits:
-        cpu: 200m
-        memory: 256Mi
-      requests:
-        cpu: 100m
-        memory: 256Mi
+  enabled: false
 
-# MinIO external ingress for presigned URL access (separate from subchart ingress)
+# MinIO ingress - disabled in stage, using real S3
 minioIngress:
-  enabled: true
-  className: "nginx"
-  annotations:
-    cert-manager.io/cluster-issuer: "letsencrypt"
-    nginx.ingress.kubernetes.io/proxy-body-size: "0"  # Disable body size limit for uploads
-  host: "minio-orch-stage.common.global.bsf.tools"
-  tls:
-    enabled: true
-    secretName: minio-tls
+  enabled: false
 
 # Redis subchart configuration (for future caching)
 redis:

migrations/007_package_versions.sql

@@ -0,0 +1,67 @@
+-- Migration: Add package_versions table for separate version tracking
+-- This separates immutable versions from mutable tags
+
+-- Create package_versions table
+CREATE TABLE IF NOT EXISTS package_versions (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    package_id UUID NOT NULL REFERENCES packages(id) ON DELETE CASCADE,
+    artifact_id VARCHAR(64) NOT NULL REFERENCES artifacts(id),
+    version VARCHAR(255) NOT NULL,
+    version_source VARCHAR(50),  -- 'explicit', 'filename', 'metadata', 'migrated_from_tag'
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
+    created_by VARCHAR(255) NOT NULL,
+    UNIQUE(package_id, version),
+    UNIQUE(package_id, artifact_id)
+);
+
+-- Indexes for common queries
+CREATE INDEX IF NOT EXISTS idx_package_versions_package_id ON package_versions(package_id);
+CREATE INDEX IF NOT EXISTS idx_package_versions_artifact_id ON package_versions(artifact_id);
+CREATE INDEX IF NOT EXISTS idx_package_versions_package_version ON package_versions(package_id, version);
+
+-- Trigger functions for ref_count management (same pattern as tags)
+CREATE OR REPLACE FUNCTION increment_version_ref_count()
+RETURNS TRIGGER AS $$
+BEGIN
+    UPDATE artifacts SET ref_count = ref_count + 1 WHERE id = NEW.artifact_id;
+    RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE OR REPLACE FUNCTION decrement_version_ref_count()
+RETURNS TRIGGER AS $$
+BEGIN
+    UPDATE artifacts SET ref_count = ref_count - 1 WHERE id = OLD.artifact_id;
+    RETURN OLD;
+END;
+$$ LANGUAGE plpgsql;
+
+-- Create triggers
+DROP TRIGGER IF EXISTS package_versions_ref_count_insert ON package_versions;
+CREATE TRIGGER package_versions_ref_count_insert
+    AFTER INSERT ON package_versions
+    FOR EACH ROW
+    EXECUTE FUNCTION increment_version_ref_count();
+
+DROP TRIGGER IF EXISTS package_versions_ref_count_delete ON package_versions;
+CREATE TRIGGER package_versions_ref_count_delete
+    AFTER DELETE ON package_versions
+    FOR EACH ROW
+    EXECUTE FUNCTION decrement_version_ref_count();
+
+-- Data migration: populate from existing semver-pattern tags
+-- This extracts versions from tags that look like version numbers
+-- Tags like "v1.0.0", "1.2.3", "2.0.0-beta" will be migrated
+-- Tags like "latest", "stable", "dev" will NOT be migrated
+INSERT INTO package_versions (package_id, artifact_id, version, version_source, created_by, created_at)
+SELECT
+    t.package_id,
+    t.artifact_id,
+    -- Strip leading 'v' if present
+    CASE WHEN t.name LIKE 'v%' THEN substring(t.name from 2) ELSE t.name END,
+    'migrated_from_tag',
+    t.created_by,
+    t.created_at
+FROM tags t
+WHERE t.name ~ '^v?[0-9]+\.[0-9]+(\.[0-9]+)?([-.][a-zA-Z0-9]+)?$'
+ON CONFLICT (package_id, version) DO NOTHING;

migrations/008_artifact_dependencies.sql

@@ -0,0 +1,48 @@
+-- Migration 008: Artifact Dependencies
+-- Adds support for declaring dependencies between artifacts
+-- Part of Package Dependency Management feature (#76)
+
+-- Create artifact_dependencies table
+CREATE TABLE IF NOT EXISTS artifact_dependencies (
+    id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+    artifact_id VARCHAR(64) NOT NULL REFERENCES artifacts(id) ON DELETE CASCADE,
+    dependency_project VARCHAR(255) NOT NULL,
+    dependency_package VARCHAR(255) NOT NULL,
+    version_constraint VARCHAR(255),
+    tag_constraint VARCHAR(255),
+    created_at TIMESTAMP WITH TIME ZONE DEFAULT CURRENT_TIMESTAMP,
+
+    -- Exactly one of version_constraint or tag_constraint must be set
+    CONSTRAINT check_constraint_type CHECK (
+        (version_constraint IS NOT NULL AND tag_constraint IS NULL) OR
+        (version_constraint IS NULL AND tag_constraint IS NOT NULL)
+    ),
+
+    -- Each artifact can only have one dependency on a specific project/package
+    CONSTRAINT unique_artifact_dependency UNIQUE (artifact_id, dependency_project, dependency_package)
+);
+
+-- Index for fast lookups by artifact_id (get all deps for an artifact)
+CREATE INDEX IF NOT EXISTS idx_artifact_dependencies_artifact_id
+    ON artifact_dependencies(artifact_id);
+
+-- Index for reverse dependency lookups (find what depends on a package)
+CREATE INDEX IF NOT EXISTS idx_artifact_dependencies_target
+    ON artifact_dependencies(dependency_project, dependency_package);
+
+-- Index for finding dependencies with specific version constraints
+CREATE INDEX IF NOT EXISTS idx_artifact_dependencies_version
+    ON artifact_dependencies(dependency_project, dependency_package, version_constraint)
+    WHERE version_constraint IS NOT NULL;
+
+-- Index for finding dependencies with specific tag constraints
+CREATE INDEX IF NOT EXISTS idx_artifact_dependencies_tag
+    ON artifact_dependencies(dependency_project, dependency_package, tag_constraint)
+    WHERE tag_constraint IS NOT NULL;
+
+COMMENT ON TABLE artifact_dependencies IS 'Stores dependencies declared by artifacts on other packages';
+COMMENT ON COLUMN artifact_dependencies.artifact_id IS 'The artifact that declares this dependency';
+COMMENT ON COLUMN artifact_dependencies.dependency_project IS 'Project name of the dependency';
+COMMENT ON COLUMN artifact_dependencies.dependency_package IS 'Package name of the dependency';
+COMMENT ON COLUMN artifact_dependencies.version_constraint IS 'Exact version required (mutually exclusive with tag_constraint)';
+COMMENT ON COLUMN artifact_dependencies.tag_constraint IS 'Tag name required (mutually exclusive with version_constraint)';