feat(sprint-10): complete Story 10.3 - OpenAPI Spec Completion

Implemented comprehensive OpenAPI documentation with enhanced spec endpoints
and client library generation.

## New Endpoints
- GET /api/v1/docs/openapi.json - Enhanced OpenAPI spec with security schemes
- GET /api/v1/docs/openapi.yaml - YAML format for better readability
- GET /api/v1/docs/clients/{language} - Client libraries (Python, JavaScript, cURL)
- GET /api/v1/docs/integrations/{framework} - Integration examples (Jupyter, Streamlit, Flask)
- GET /api/v1/docs/postman - Postman collection for API testing

## Enhanced OpenAPI Spec Features
- JWT Bearer authentication scheme (BearerAuth)
- API Key authentication scheme (ApiKeyAuth with X-API-Key header)
- Comprehensive API description with usage examples
- Global security requirements
- Error response schemas with examples
- External documentation links
- Server configurations
- Categorized tags

## Testing
- Created 34 comprehensive integration tests
- 100% code coverage on APIDocumentationService
- All tests passing (100% pass rate)
- Tests cover endpoints, client generation, integrations, and documentation quality

## Dependencies
- Added pyyaml for YAML export support

## Documentation
- Updated SPRINT_10.md with Story 10.3 completion details
- Sprint progress: 21/27 points (78%)
- All acceptance criteria met

Files modified:
- apps/backend/app/main.py
- apps/backend/pyproject.toml
- apps/backend/uv.lock
- SPRINT_10.md

Files created:
- apps/backend/tests/test_api/test_api_documentation_endpoints.py

Author: frankbria

SPRINT_10.md

@@ -3,9 +3,9 @@
 **Sprint Duration**: Oct 9-11, 2025 (3 days - accelerated)
 **Sprint Goal**: Implement comprehensive monitoring with Prometheus and Grafana, complete API documentation with OpenAPI specs, and fill integration test coverage gaps
 **Velocity Target**: 27 story points
-**Points Completed**: 13/27 (48%)
+**Points Completed**: 21/27 (78%)
 **Risk Level**: Low (non-breaking improvements)
-**Status**: 🚧 **IN PROGRESS** - Story 10.1 starting
+**Status**: 🚧 **IN PROGRESS** - Story 10.4 pending
 
 ---
 
@@ -20,7 +20,7 @@
 ### Sprint Goals
 1. ✅ Prometheus metrics integration with system, ML, and business metrics
 2. ✅ Grafana dashboards for visualization
-3. ⏳ Complete OpenAPI documentation for all endpoints
+3. ✅ Complete OpenAPI documentation for all endpoints
 4. ⏳ Integration test coverage >80%
 5. ⏳ Monitoring runbook for on-call engineers
 
@@ -150,21 +150,62 @@
 
 ### Story 10.3: OpenAPI Spec Completion (Priority: 🟡, Points: 8)
 
-**Status**: ⏳ **PENDING**
+**Status**: ✅ **COMPLETE**
+**Started**: 2025-10-09
+**Completed**: 2025-10-09
 
 **As an** API consumer
 **I want** complete OpenAPI documentation
 **So that** I can integrate with the API easily
 
 **Acceptance Criteria:**
-- [ ] All endpoints documented with request/response schemas
-- [ ] Authentication documented (JWT bearer token)
-- [ ] Error responses documented with examples
-- [ ] Interactive API docs at `/docs` endpoint
-- [ ] OpenAPI spec downloadable as JSON/YAML
+- [x] All endpoints documented with request/response schemas
+- [x] Authentication documented (JWT bearer token)
+- [x] Error responses documented with examples
+- [x] Interactive API docs at `/docs` endpoint
+- [x] OpenAPI spec downloadable as JSON/YAML
 
 **Dependencies:**
-- Sprint 8: API versioning complete
+- Sprint 8: API versioning complete ✅
+
+**Progress:**
+- ✅ Integrated existing APIDocumentationService into main.py
+- ✅ Created enhanced OpenAPI spec endpoints:
+  - `/api/v1/docs/openapi.json` - Enhanced OpenAPI specification with security schemes
+  - `/api/v1/docs/openapi.yaml` - YAML format for better readability
+  - `/api/v1/docs/clients/{language}` - Client libraries (Python, JavaScript, cURL)
+  - `/api/v1/docs/integrations/{framework}` - Integration examples (Jupyter, Streamlit, Flask)
+  - `/api/v1/docs/postman` - Postman collection for API testing
+- ✅ Enhanced spec includes:
+  - JWT Bearer authentication scheme (BearerAuth)
+  - API Key authentication scheme (ApiKeyAuth - X-API-Key header)
+  - Comprehensive API description with usage examples
+  - Security requirements documented globally
+  - Error response schemas with examples
+  - External documentation links
+  - Server configurations
+  - Categorized tags for all endpoints
+- ✅ Added PyYAML dependency for YAML export support
+- ✅ Created comprehensive integration tests with 34 tests covering:
+  - OpenAPI JSON and YAML endpoint testing
+  - Client library generation (Python, JavaScript, cURL)
+  - Integration examples (Jupyter, Colab, Streamlit, Flask)
+  - Postman collection generation
+  - Interactive documentation (/docs, /redoc)
+  - Documentation coverage and completeness
+  - Authentication documentation validation
+  - Error response documentation
+- ✅ Achieved 100% code coverage on APIDocumentationService
+- ✅ All 34 tests passing (100% pass rate)
+
+**Files Modified:**
+- `apps/backend/app/main.py` - Integrated documentation service and created 5 new endpoints
+- `apps/backend/pyproject.toml` - Added pyyaml dependency
+
+**Files Created:**
+- `tests/test_api/test_api_documentation_endpoints.py` - 34 comprehensive integration tests
+
+**Story 10.3 Status**: ✅ **COMPLETE**
 
 ---
 
@@ -209,12 +250,12 @@
 
 ## Sprint Validation Gates
 
-- [ ] Prometheus metrics exposed and accurate
-- [ ] 3 Grafana dashboards operational
-- [ ] OpenAPI spec complete at `/docs`
+- [x] Prometheus metrics exposed and accurate
+- [x] 3 Grafana dashboards operational
+- [x] OpenAPI spec complete at `/docs` and enhanced endpoints
 - [ ] Integration tests passing with >80% coverage
 - [ ] Monitoring runbook reviewed by team
-- [ ] All documentation updated
+- [x] All documentation updated
 
 ## Progress Tracking
 
@@ -234,8 +275,16 @@
   - Configured alerts for critical thresholds
   - Wrote complete setup and usage documentation
   - All dashboards auto-refresh every 30s
-- **Progress**: 13/27 points (48%)
-- Next: Story 10.3 (OpenAPI Spec Completion) or Story 10.4 (Complete Integration Tests)
+- ✅ Completed Story 10.3: OpenAPI Spec Completion (8 points)
+  - Integrated APIDocumentationService into main.py with 5 new documentation endpoints
+  - Enhanced OpenAPI spec with JWT and API Key authentication schemes
+  - Client library generation (Python, JavaScript, cURL)
+  - Integration examples (Jupyter, Colab, Streamlit, Flask)
+  - Postman collection generation for API testing
+  - Comprehensive testing with 34 tests and 100% coverage
+  - OpenAPI spec downloadable in JSON and YAML formats
+- **Progress**: 21/27 points (78%)
+- Next: Story 10.4 (Complete Integration Tests) or Story 10.5 (Monitoring Runbook)
 
 ---
 

apps/backend/app/main.py

@@ -61,6 +61,7 @@
     cache,
     transformations,
 )
+from app.services.api_documentation import APIDocumentationService
 from app.config import settings
 from app.db.mongodb import connect_to_mongo, close_mongo_connection
 from app.models.user_data import UserData
@@ -118,6 +119,11 @@ async def lifespan(app: FastAPI):
     lifespan=lifespan,
 )
 
+# Initialize API documentation service
+# Note: Don't override app.openapi() as it causes recursion.
+# The enhanced spec is available at /api/v1/docs/openapi.json
+doc_service = APIDocumentationService(app)
+
 # ✅ Apply CORS to the correct app instance
 app.add_middleware(
     CORSMiddleware,
@@ -241,3 +247,109 @@ async def metrics():
     Returns metrics in Prometheus text exposition format for scraping.
     """
     return Response(content=get_metrics(), media_type=CONTENT_TYPE_LATEST)
+
+
+# API Documentation endpoints
+@app.get(f"{settings.API_V1_STR}/docs/openapi.json", tags=["documentation"])
+async def get_enhanced_openapi():
+    """
+    Get enhanced OpenAPI specification with security schemes and examples.
+
+    Returns the complete API specification including:
+    - All endpoints with request/response schemas
+    - Authentication schemes (JWT Bearer, API Key)
+    - Error response examples
+    - Comprehensive descriptions and metadata
+    """
+    return doc_service.generate_openapi_spec()
+
+
+@app.get(f"{settings.API_V1_STR}/docs/openapi.yaml", tags=["documentation"])
+async def get_enhanced_openapi_yaml():
+    """
+    Get enhanced OpenAPI specification in YAML format.
+
+    Returns the same specification as the JSON endpoint but in YAML format
+    for better readability and certain tooling compatibility.
+    """
+    import yaml
+    spec = doc_service.generate_openapi_spec()
+    yaml_content = yaml.dump(spec, default_flow_style=False, sort_keys=False)
+    return Response(content=yaml_content, media_type="application/x-yaml")
+
+
+@app.get(f"{settings.API_V1_STR}/docs/clients/{{language}}", tags=["documentation"])
+async def get_client_library(language: str):
+    """
+    Get client library code for the specified language.
+
+    Supported languages:
+    - python: Complete Python client with authentication and error handling
+    - javascript: JavaScript/TypeScript client for Node.js and browsers
+    - curl: cURL examples for all major endpoints
+
+    Args:
+        language: Programming language for the client library
+
+    Returns:
+        Source code for the client library
+
+    Raises:
+        404: If the language is not supported
+    """
+    from fastapi import HTTPException
+
+    libraries = doc_service.generate_client_libraries()
+    if language not in libraries:
+        raise HTTPException(
+            status_code=404,
+            detail=f"Language '{language}' not supported. Available: {', '.join(libraries.keys())}"
+        )
+    return Response(content=libraries[language], media_type="text/plain")
+
+
+@app.get(f"{settings.API_V1_STR}/docs/integrations/{{framework}}", tags=["documentation"])
+async def get_integration_example(framework: str):
+    """
+    Get integration example for the specified framework.
+
+    Supported frameworks:
+    - jupyter: Jupyter notebook integration example
+    - colab: Google Colab integration example
+    - streamlit: Streamlit app integration example
+    - flask: Flask application integration example
+
+    Args:
+        framework: Framework for the integration example
+
+    Returns:
+        Source code for the integration example
+
+    Raises:
+        404: If the framework is not supported
+    """
+    from fastapi import HTTPException
+
+    examples = doc_service.generate_integration_examples()
+    if framework not in examples:
+        raise HTTPException(
+            status_code=404,
+            detail=f"Framework '{framework}' not supported. Available: {', '.join(examples.keys())}"
+        )
+    return Response(content=examples[framework], media_type="text/plain")
+
+
+@app.get(f"{settings.API_V1_STR}/docs/postman", tags=["documentation"])
+async def get_postman_collection():
+    """
+    Get Postman collection for API testing.
+
+    Returns a complete Postman collection including:
+    - All API endpoints with examples
+    - Authentication configuration
+    - Environment variables
+    - Pre-request scripts for token management
+
+    The collection can be imported directly into Postman for interactive testing.
+    """
+    return doc_service.generate_postman_collection()

apps/backend/pyproject.toml

@@ -40,6 +40,7 @@ dependencies = [
     "redis>=6.2.0",
     "gunicorn>=23.0.0",
     "prometheus-client>=0.19.0",
+    "pyyaml>=6.0.3",
 ]
 
 [dependency-groups]