Add separate version tracking for artifacts

CHANGELOG.md

@@ -7,6 +7,18 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 ### Added
+- 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)
@@ -19,6 +31,7 @@ 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
+- 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

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
+- `latest` - Implicit lookup (checks version first, then tag, then artifact ID)
-- `v1.0.0` - Version tag
+- `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 +151,84 @@ 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 $$;
+        """,
+        # Create ref_count trigger functions for package_versions
+        """
+        CREATE OR REPLACE FUNCTION increment_version_ref_count()
+        RETURNS TRIGGER AS $$
+        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 $$;
+        """,
+        # Migrate existing semver tags to package_versions
+        """
+        DO $$
+        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/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+)?)$",  # name-version
+        r"^(.+)-v?(\d+\.\d+(?:\.\d+)?(?:[-_]\w+)?)$",  # name-version or name-vversion
-        r"^(.+)_(\d+\.\d+(?:\.\d+)?(?:[-._]\w+)?)$",   # name_version
+        r"^(.+)_v?(\d+\.\d+(?:\.\d+)?(?:[-_]\w+)?)$",  # 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 +116,7 @@ class Artifact(Base):
 
     tags = relationship("Tag", back_populates="artifact")
     uploads = relationship("Upload", back_populates="artifact")
+    versions = relationship("PackageVersion", back_populates="artifact")
 
     @property
     def sha256(self) -> str:
@@ -197,6 +201,38 @@ 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"
 

backend/app/routes.py

@@ -16,7 +16,7 @@ from fastapi import (
 )
 from fastapi.responses import StreamingResponse, RedirectResponse
 from sqlalchemy.orm import Session
-from sqlalchemy import or_, func, text
+from sqlalchemy import or_, and_, func, text
 from typing import List, Optional, Literal
 import math
 import io
@@ -46,6 +46,7 @@ from .models import (
     AuditLog,
     User,
     AccessPermission,
+    PackageVersion,
 )
 from .schemas import (
     ProjectCreate,
@@ -116,6 +117,8 @@ from .schemas import (
     OIDCConfigUpdate,
     OIDCStatusResponse,
     OIDCLoginResponse,
+    PackageVersionResponse,
+    PackageVersionDetailResponse,
 )
 from .metadata import extract_metadata
 from .config import get_settings
@@ -237,6 +240,103 @@ def _decrement_ref_count(db: Session, artifact_id: str) -> int:
     return artifact.ref_count
 
 
+import re
+
+# Regex pattern for detecting version in filename
+# Matches: name-1.0.0, name_1.0.0, name-v1.0.0, etc.
+# Supports: X.Y, X.Y.Z, X.Y.Z-alpha, X.Y.Z.beta1, X.Y.Z_rc2
+VERSION_FILENAME_PATTERN = re.compile(
+    r"[-_]v?(\d+\.\d+(?:\.\d+)?(?:[-_][a-zA-Z0-9]+)?)(?:\.tar|\.zip|\.tgz|\.gz|\.bz2|\.xz|$)"
+)
+
+
+def _detect_version(
+    explicit_version: Optional[str],
+    metadata: dict,
+    filename: str,
+) -> tuple[Optional[str], Optional[str]]:
+    """
+    Detect version from explicit parameter, metadata, or filename.
+
+    Priority:
+    1. Explicit version parameter (user provided)
+    2. Version from package metadata (deb, rpm, whl, jar)
+    3. Version from filename pattern
+
+    Returns:
+        tuple of (version, source) where source is one of:
+        - 'explicit': User provided the version
+        - 'metadata': Extracted from package metadata
+        - 'filename': Parsed from filename
+        - None: No version could be determined
+    """
+    # 1. Explicit version takes priority
+    if explicit_version:
+        return explicit_version, "explicit"
+
+    # 2. Try metadata extraction (from deb, rpm, whl, jar, etc.)
+    if metadata.get("version"):
+        return metadata["version"], "metadata"
+
+    # 3. Try filename pattern matching
+    match = VERSION_FILENAME_PATTERN.search(filename)
+    if match:
+        return match.group(1), "filename"
+
+    return None, None
+
+
+def _create_or_update_version(
+    db: Session,
+    package_id: str,
+    artifact_id: str,
+    version: str,
+    version_source: str,
+    user_id: str,
+) -> PackageVersion:
+    """
+    Create a version record for a package-artifact pair.
+
+    Raises HTTPException 409 if version already exists for this package.
+    """
+    # Check if version already exists
+    existing = (
+        db.query(PackageVersion)
+        .filter(PackageVersion.package_id == package_id, PackageVersion.version == version)
+        .first()
+    )
+    if existing:
+        raise HTTPException(
+            status_code=409,
+            detail=f"Version {version} already exists in this package",
+        )
+
+    # Check if artifact already has a version in this package
+    existing_artifact_version = (
+        db.query(PackageVersion)
+        .filter(
+            PackageVersion.package_id == package_id,
+            PackageVersion.artifact_id == artifact_id,
+        )
+        .first()
+    )
+    if existing_artifact_version:
+        # Artifact already has a version, return it
+        return existing_artifact_version
+
+    # Create new version record
+    pkg_version = PackageVersion(
+        package_id=package_id,
+        artifact_id=artifact_id,
+        version=version,
+        version_source=version_source,
+        created_by=user_id,
+    )
+    db.add(pkg_version)
+    db.flush()
+    return pkg_version
+
+
 def _create_or_update_tag(
     db: Session,
     package_id: str,
@@ -2147,6 +2247,7 @@ def upload_artifact(
     request: Request,
     file: UploadFile = File(...),
     tag: Optional[str] = Form(None),
+    version: Optional[str] = Form(None),
     db: Session = Depends(get_db),
     storage: S3Storage = Depends(get_storage),
     content_length: Optional[int] = Header(None, alias="Content-Length"),
@@ -2214,6 +2315,11 @@ def upload_artifact(
             io.BytesIO(file_content), file.filename, file.content_type
         )
 
+    # Detect version (explicit > metadata > filename)
+    detected_version, version_source = _detect_version(
+        version, file_metadata, file.filename or ""
+    )
+
     # Store file (uses multipart for large files) with error handling
     try:
         storage_result = storage.store(file.file, content_length)
@@ -2383,6 +2489,25 @@ def upload_artifact(
     if tag:
         _create_or_update_tag(db, package.id, tag, storage_result.sha256, user_id)
 
+    # Create version record if version was detected
+    pkg_version = None
+    if detected_version:
+        try:
+            pkg_version = _create_or_update_version(
+                db, package.id, storage_result.sha256, detected_version, version_source, user_id
+            )
+        except HTTPException as e:
+            # Version conflict (409) - log but don't fail the upload
+            if e.status_code == 409:
+                logger.warning(
+                    f"Version {detected_version} already exists for package {package_name}, "
+                    f"upload continues without version assignment"
+                )
+                detected_version = None
+                version_source = None
+            else:
+                raise
+
     # Log deduplication event
     if deduplicated:
         logger.info(
@@ -2437,6 +2562,8 @@ def upload_artifact(
         project=project_name,
         package=package_name,
         tag=tag,
+        version=detected_version,
+        version_source=version_source,
         checksum_md5=storage_result.md5,
         checksum_sha1=storage_result.sha1,
         s3_etag=storage_result.s3_etag,
@@ -2754,15 +2881,30 @@ def _resolve_artifact_ref(
     package: Package,
     db: Session,
 ) -> Optional[Artifact]:
-    """Resolve a reference (tag name, artifact:hash, tag:name) to an artifact"""
+    """Resolve a reference (tag name, version, artifact:hash, tag:name, version:X.Y.Z) to an artifact.
+
+    Resolution order for implicit refs (no prefix):
+    1. Version (immutable)
+    2. Tag (mutable)
+    3. Artifact ID (direct hash)
+    """
     artifact = None
 
     # Check for explicit prefixes
     if ref.startswith("artifact:"):
         artifact_id = ref[9:]
         artifact = db.query(Artifact).filter(Artifact.id == artifact_id).first()
-    elif ref.startswith("tag:") or ref.startswith("version:"):
+    elif ref.startswith("version:"):
-        tag_name = ref.split(":", 1)[1]
+        version_str = ref[8:]
+        pkg_version = (
+            db.query(PackageVersion)
+            .filter(PackageVersion.package_id == package.id, PackageVersion.version == version_str)
+            .first()
+        )
+        if pkg_version:
+            artifact = db.query(Artifact).filter(Artifact.id == pkg_version.artifact_id).first()
+    elif ref.startswith("tag:"):
+        tag_name = ref[4:]
         tag = (
             db.query(Tag)
             .filter(Tag.package_id == package.id, Tag.name == tag_name)
@@ -2771,15 +2913,25 @@ def _resolve_artifact_ref(
         if tag:
             artifact = db.query(Artifact).filter(Artifact.id == tag.artifact_id).first()
     else:
-        # Try as tag name first
+        # Implicit ref: try version first, then tag, then artifact ID
-        tag = (
+        # Try as version first
-            db.query(Tag).filter(Tag.package_id == package.id, Tag.name == ref).first()
+        pkg_version = (
+            db.query(PackageVersion)
+            .filter(PackageVersion.package_id == package.id, PackageVersion.version == ref)
+            .first()
         )
-        if tag:
+        if pkg_version:
-            artifact = db.query(Artifact).filter(Artifact.id == tag.artifact_id).first()
+            artifact = db.query(Artifact).filter(Artifact.id == pkg_version.artifact_id).first()
         else:
-            # Try as direct artifact ID
+            # Try as tag name
-            artifact = db.query(Artifact).filter(Artifact.id == ref).first()
+            tag = (
+                db.query(Tag).filter(Tag.package_id == package.id, Tag.name == ref).first()
+            )
+            if tag:
+                artifact = db.query(Artifact).filter(Artifact.id == tag.artifact_id).first()
+            else:
+                # Try as direct artifact ID
+                artifact = db.query(Artifact).filter(Artifact.id == ref).first()
 
     return artifact
 
@@ -3177,6 +3329,224 @@ def download_artifact_compat(
     )
 
 
+# Version routes
+@router.get(
+    "/api/v1/project/{project_name}/{package_name}/versions",
+    response_model=PaginatedResponse[PackageVersionResponse],
+)
+def list_versions(
+    project_name: str,
+    package_name: str,
+    page: int = Query(default=1, ge=1, description="Page number"),
+    limit: int = Query(default=20, ge=1, le=100, description="Items per page"),
+    search: Optional[str] = Query(default=None, description="Search by version string"),
+    sort: str = Query(default="version", description="Sort field (version, created_at)"),
+    order: str = Query(default="desc", description="Sort order (asc, desc)"),
+    db: Session = Depends(get_db),
+):
+    """List all versions for a package."""
+    project = db.query(Project).filter(Project.name == project_name).first()
+    if not project:
+        raise HTTPException(status_code=404, detail="Project not found")
+
+    package = (
+        db.query(Package)
+        .filter(Package.project_id == project.id, Package.name == package_name)
+        .first()
+    )
+    if not package:
+        raise HTTPException(status_code=404, detail="Package not found")
+
+    # Validate sort field
+    valid_sort_fields = {"version": PackageVersion.version, "created_at": PackageVersion.created_at}
+    if sort not in valid_sort_fields:
+        raise HTTPException(
+            status_code=400,
+            detail=f"Invalid sort field. Must be one of: {', '.join(valid_sort_fields.keys())}",
+        )
+
+    # Validate order
+    if order not in ("asc", "desc"):
+        raise HTTPException(status_code=400, detail="Invalid order. Must be 'asc' or 'desc'")
+
+    # Base query with JOIN to artifact for metadata
+    query = (
+        db.query(PackageVersion, Artifact)
+        .join(Artifact, PackageVersion.artifact_id == Artifact.id)
+        .filter(PackageVersion.package_id == package.id)
+    )
+
+    # Apply search filter
+    if search:
+        query = query.filter(PackageVersion.version.ilike(f"%{search}%"))
+
+    # Get total count before pagination
+    total = query.count()
+
+    # Apply sorting
+    sort_column = valid_sort_fields[sort]
+    if order == "desc":
+        query = query.order_by(sort_column.desc())
+    else:
+        query = query.order_by(sort_column.asc())
+
+    # Apply pagination
+    offset = (page - 1) * limit
+    results = query.offset(offset).limit(limit).all()
+
+    # Get tags for each version's artifact
+    version_responses = []
+    for pkg_version, artifact in results:
+        # Get tags pointing to this artifact in this package
+        tags = (
+            db.query(Tag.name)
+            .filter(Tag.package_id == package.id, Tag.artifact_id == artifact.id)
+            .all()
+        )
+        tag_names = [t[0] for t in tags]
+
+        version_responses.append(
+            PackageVersionResponse(
+                id=pkg_version.id,
+                package_id=pkg_version.package_id,
+                artifact_id=pkg_version.artifact_id,
+                version=pkg_version.version,
+                version_source=pkg_version.version_source,
+                created_at=pkg_version.created_at,
+                created_by=pkg_version.created_by,
+                size=artifact.size,
+                content_type=artifact.content_type,
+                original_name=artifact.original_name,
+                tags=tag_names,
+            )
+        )
+
+    total_pages = math.ceil(total / limit) if total > 0 else 1
+    has_more = page < total_pages
+
+    return PaginatedResponse(
+        items=version_responses,
+        pagination=PaginationMeta(
+            page=page,
+            limit=limit,
+            total=total,
+            total_pages=total_pages,
+            has_more=has_more,
+        ),
+    )
+
+
+@router.get(
+    "/api/v1/project/{project_name}/{package_name}/versions/{version}",
+    response_model=PackageVersionDetailResponse,
+)
+def get_version(
+    project_name: str,
+    package_name: str,
+    version: str,
+    db: Session = Depends(get_db),
+):
+    """Get details of a specific version."""
+    project = db.query(Project).filter(Project.name == project_name).first()
+    if not project:
+        raise HTTPException(status_code=404, detail="Project not found")
+
+    package = (
+        db.query(Package)
+        .filter(Package.project_id == project.id, Package.name == package_name)
+        .first()
+    )
+    if not package:
+        raise HTTPException(status_code=404, detail="Package not found")
+
+    pkg_version = (
+        db.query(PackageVersion)
+        .filter(PackageVersion.package_id == package.id, PackageVersion.version == version)
+        .first()
+    )
+    if not pkg_version:
+        raise HTTPException(status_code=404, detail="Version not found")
+
+    artifact = db.query(Artifact).filter(Artifact.id == pkg_version.artifact_id).first()
+
+    # Get tags pointing to this artifact
+    tags = (
+        db.query(Tag.name)
+        .filter(Tag.package_id == package.id, Tag.artifact_id == artifact.id)
+        .all()
+    )
+    tag_names = [t[0] for t in tags]
+
+    return PackageVersionDetailResponse(
+        id=pkg_version.id,
+        package_id=pkg_version.package_id,
+        artifact_id=pkg_version.artifact_id,
+        version=pkg_version.version,
+        version_source=pkg_version.version_source,
+        created_at=pkg_version.created_at,
+        created_by=pkg_version.created_by,
+        size=artifact.size,
+        content_type=artifact.content_type,
+        original_name=artifact.original_name,
+        tags=tag_names,
+        format_metadata=artifact.artifact_metadata,
+        checksum_md5=artifact.checksum_md5,
+        checksum_sha1=artifact.checksum_sha1,
+    )
+
+
+@router.delete(
+    "/api/v1/project/{project_name}/{package_name}/versions/{version}",
+    status_code=204,
+)
+def delete_version(
+    project_name: str,
+    package_name: str,
+    version: str,
+    request: Request,
+    db: Session = Depends(get_db),
+    current_user: User = Depends(require_admin),
+):
+    """Delete a version (admin only). Does not delete the underlying artifact."""
+    project = db.query(Project).filter(Project.name == project_name).first()
+    if not project:
+        raise HTTPException(status_code=404, detail="Project not found")
+
+    package = (
+        db.query(Package)
+        .filter(Package.project_id == project.id, Package.name == package_name)
+        .first()
+    )
+    if not package:
+        raise HTTPException(status_code=404, detail="Package not found")
+
+    pkg_version = (
+        db.query(PackageVersion)
+        .filter(PackageVersion.package_id == package.id, PackageVersion.version == version)
+        .first()
+    )
+    if not pkg_version:
+        raise HTTPException(status_code=404, detail="Version not found")
+
+    artifact_id = pkg_version.artifact_id
+
+    # Delete version (triggers will decrement ref_count)
+    db.delete(pkg_version)
+
+    # Audit log
+    _log_audit(
+        db,
+        action="version.delete",
+        resource=f"project/{project_name}/{package_name}/version/{version}",
+        user_id=current_user.username,
+        source_ip=request.client.host if request.client else None,
+        details={"artifact_id": artifact_id},
+    )
+
+    db.commit()
+    return Response(status_code=204)
+
+
 # Tag routes
 @router.get(
     "/api/v1/project/{project_name}/{package_name}/tags",
@@ -3224,10 +3594,17 @@ def list_tags(
             status_code=400, detail="Invalid order. Must be 'asc' or 'desc'"
         )
 
-    # Base query with JOIN to artifact for metadata
+    # Base query with JOIN to artifact for metadata and LEFT JOIN to version
     query = (
-        db.query(Tag, Artifact)
+        db.query(Tag, Artifact, PackageVersion.version)
         .join(Artifact, Tag.artifact_id == Artifact.id)
+        .outerjoin(
+            PackageVersion,
+            and_(
+                PackageVersion.package_id == Tag.package_id,
+                PackageVersion.artifact_id == Tag.artifact_id,
+            ),
+        )
         .filter(Tag.package_id == package.id)
     )
 
@@ -3264,9 +3641,9 @@ def list_tags(
     # Calculate total pages
     total_pages = math.ceil(total / limit) if total > 0 else 1
 
-    # Build detailed responses with artifact metadata
+    # Build detailed responses with artifact metadata and version
     detailed_tags = []
-    for tag, artifact in results:
+    for tag, artifact, version in results:
         detailed_tags.append(
             TagDetailResponse(
                 id=tag.id,
@@ -3280,6 +3657,7 @@ def list_tags(
                 artifact_original_name=artifact.original_name,
                 artifact_created_at=artifact.created_at,
                 artifact_format_metadata=artifact.format_metadata,
+                version=version,
             )
         )
 
@@ -3396,8 +3774,15 @@ def get_tag(
         raise HTTPException(status_code=404, detail="Package not found")
 
     result = (
-        db.query(Tag, Artifact)
+        db.query(Tag, Artifact, PackageVersion.version)
         .join(Artifact, Tag.artifact_id == Artifact.id)
+        .outerjoin(
+            PackageVersion,
+            and_(
+                PackageVersion.package_id == Tag.package_id,
+                PackageVersion.artifact_id == Tag.artifact_id,
+            ),
+        )
         .filter(Tag.package_id == package.id, Tag.name == tag_name)
         .first()
     )
@@ -3405,7 +3790,7 @@ def get_tag(
     if not result:
         raise HTTPException(status_code=404, detail="Tag not found")
 
-    tag, artifact = result
+    tag, artifact, version = result
     return TagDetailResponse(
         id=tag.id,
         package_id=tag.package_id,
@@ -3418,6 +3803,7 @@ def get_tag(
         artifact_original_name=artifact.original_name,
         artifact_created_at=artifact.created_at,
         artifact_format_metadata=artifact.format_metadata,
+        version=version,
     )
 
 
@@ -3915,10 +4301,17 @@ def list_all_tags(
     List all tags globally with filtering by project, package, name, etc.
     """
     query = (
-        db.query(Tag, Package, Project, Artifact)
+        db.query(Tag, Package, Project, Artifact, PackageVersion.version)
         .join(Package, Tag.package_id == Package.id)
         .join(Project, Package.project_id == Project.id)
         .join(Artifact, Tag.artifact_id == Artifact.id)
+        .outerjoin(
+            PackageVersion,
+            and_(
+                PackageVersion.package_id == Tag.package_id,
+                PackageVersion.artifact_id == Tag.artifact_id,
+            ),
+        )
     )
 
     # Apply filters
@@ -3982,8 +4375,9 @@ def list_all_tags(
             package_name=pkg.name,
             artifact_size=artifact.size,
             artifact_content_type=artifact.content_type,
+            version=version,
         )
-        for tag, pkg, proj, artifact in results
+        for tag, pkg, proj, artifact, version in results
     ]
 
     return PaginatedResponse(

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
@@ -418,6 +423,7 @@ 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
@@ -484,6 +490,35 @@ 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"""

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
 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",
@@ -115,6 +119,7 @@ TEST_ARTIFACTS = [
         "filename": "auth-lib-1.0.0.go",
         "content_type": "text/x-go",
         "tags": ["v1.0.0", "latest"],
+        "version": "1.0.0",
     },
 ]
 
@@ -160,9 +165,10 @@ 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 +190,11 @@ 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 +203,7 @@ 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 +217,18 @@ 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(
@@ -218,5 +241,5 @@ def seed_database(db: Session) -> None:
             tag_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, and {version_count} versions")
     logger.info("Database seeding complete")

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",

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")

frontend/src/api.ts

@@ -32,6 +32,7 @@ import {
   OIDCConfig,
   OIDCConfigUpdate,
   OIDCStatus,
+  PackageVersion,
 } from './types';
 
 const API_BASE = '/api/v1';
@@ -239,12 +240,21 @@ 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}/${packageName}/upload`, {
     method: 'POST',
@@ -443,3 +453,38 @@ export function getOIDCLoginUrl(returnTo?: string): string {
   const query = params.toString();
   return `${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}`);
+  }
+}

frontend/src/pages/PackagePage.css

@@ -324,6 +324,86 @@ 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;

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 { listTags, getDownloadUrl, getPackage, getMyProjectAccess, createTag, UnauthorizedError, ForbiddenError } from '../api';
 import { Breadcrumb } from '../components/Breadcrumb';
 import { Badge } from '../components/Badge';
 import { SearchInput } from '../components/SearchInput';
@@ -64,6 +64,9 @@ 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);
 
   // Derived permissions
   const canWrite = accessLevel === 'write' || accessLevel === 'admin';
@@ -154,6 +157,30 @@ 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' });
   };
@@ -182,6 +209,13 @@ function PackagePage() {
       sortable: true,
       render: (t: TagDetail) => <strong>{t.name}</strong>,
     },
+    {
+      key: 'version',
+      header: 'Version',
+      render: (t: TagDetail) => (
+        <span className="version-badge">{t.version || '-'}</span>
+      ),
+    },
     {
       key: 'artifact_id',
       header: 'Artifact ID',
@@ -433,6 +467,50 @@ 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>

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

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;