Add integration tests for deduplication and ref_count

- Add test_integration_uploads.py with 12 tests for duplicate upload scenarios
- Add test_ref_count.py with 7 tests for ref_count management
- Fix ArtifactDetailResponse to include sha256 and checksum fields
- Fix health check SQL warning by wrapping in text()
- Update tests to use unique content per test run for idempotency

backend/tests/conftest.py

@@ -199,3 +199,119 @@ def test_app():
     from app.main import app
 
     return TestClient(app)
+
+
+# =============================================================================
+# Integration Test Fixtures
+# =============================================================================
+
+
+@pytest.fixture
+def integration_client():
+    """
+    Create a test client for integration tests.
+
+    Uses the real database and MinIO from docker-compose.local.yml.
+    """
+    from httpx import Client
+
+    # Connect to the running orchard-server container
+    base_url = os.environ.get("ORCHARD_TEST_URL", "http://localhost:8080")
+
+    with Client(base_url=base_url, timeout=30.0) as client:
+        yield client
+
+
+@pytest.fixture
+def unique_test_id():
+    """Generate a unique ID for test isolation."""
+    import uuid
+
+    return f"test-{uuid.uuid4().hex[:8]}"
+
+
+@pytest.fixture
+def test_project(integration_client, unique_test_id):
+    """
+    Create a test project and clean it up after the test.
+
+    Yields the project name.
+    """
+    project_name = f"test-project-{unique_test_id}"
+
+    # Create project
+    response = integration_client.post(
+        "/api/v1/projects",
+        json={"name": project_name, "description": "Test project", "is_public": True},
+    )
+    assert response.status_code == 200, f"Failed to create project: {response.text}"
+
+    yield project_name
+
+    # Cleanup: delete project
+    try:
+        integration_client.delete(f"/api/v1/projects/{project_name}")
+    except Exception:
+        pass  # Ignore cleanup errors
+
+
+@pytest.fixture
+def test_package(integration_client, test_project, unique_test_id):
+    """
+    Create a test package within a test project.
+
+    Yields (project_name, package_name) tuple.
+    """
+    package_name = f"test-package-{unique_test_id}"
+
+    # Create package
+    response = integration_client.post(
+        f"/api/v1/project/{test_project}/packages",
+        json={"name": package_name, "description": "Test package"},
+    )
+    assert response.status_code == 200, f"Failed to create package: {response.text}"
+
+    yield (test_project, package_name)
+
+    # Cleanup handled by test_project fixture (cascade delete)
+
+
+@pytest.fixture
+def test_content():
+    """
+    Generate unique test content for each test.
+
+    Returns (content_bytes, expected_sha256) tuple.
+    """
+    import uuid
+
+    content = f"test-content-{uuid.uuid4().hex}".encode()
+    sha256 = compute_sha256(content)
+    return (content, sha256)
+
+
+def upload_test_file(
+    client,
+    project: str,
+    package: str,
+    content: bytes,
+    filename: str = "test.bin",
+    tag: str = None,
+) -> dict:
+    """
+    Helper function to upload a test file.
+
+    Returns the upload response as a dict.
+    """
+    files = {"file": (filename, io.BytesIO(content), "application/octet-stream")}
+    data = {}
+    if tag:
+        data["tag"] = tag
+
+    response = client.post(
+        f"/api/v1/project/{project}/{package}/upload",
+        files=files,
+        data=data if data else None,
+    )
+    assert response.status_code == 200, f"Upload failed: {response.text}"
+    return response.json()