Add unit tests for dependency exception handling

- Created test_dependency_exception_handling.py with 5 comprehensive tests
- Tests verify proper handling of HTTPException in async generator dependencies
- All tests pass, confirming fix for 'generator didn't stop after athrow()' error
- Updated instructions with complete task documentation

docs/instructions.md

@@ -119,25 +119,40 @@ For each task completed:
 
 ## TODO List:
 
-Task completed! ✅
+✅ **Task Completed Successfully**
 
-### Issue Fixed
+### Issue Fixed: RuntimeError: generator didn't stop after athrow()
 
-Fixed the `RuntimeError: generator didn't stop after athrow()` error in the `/api/anime/add` endpoint.
+**Problem:**
+The `/api/anime/add` endpoint was throwing a 500 error with `RuntimeError: generator didn't stop after athrow()` when validation errors (HTTPException) were raised after database session dependencies yielded.
 
 **Root Cause:**
-The error occurred when an `HTTPException` was raised in an endpoint after a database session was yielded from the `get_optional_database_session` dependency. The async generator didn't properly handle exceptions thrown back into it, causing Python's async context manager to fail with "generator didn't stop after athrow()".
+Async generator dependencies (`get_database_session` and `get_optional_database_session`) didn't properly handle exceptions thrown back into them after yielding. When an `HTTPException` was raised in the endpoint for validation errors, Python's async context manager tried to propagate the exception to the generator, but without proper exception handling around the yield statement, it resulted in the "generator didn't stop after athrow()" error.
 
 **Solution:**
-Added proper exception handling in both `get_database_session` and `get_optional_database_session` dependency functions by wrapping the yield statement in a try-except block that re-raises any exceptions, allowing FastAPI to handle them correctly.
+Added proper exception handling in both database session dependencies by wrapping the `yield` statement with a try-except block that re-raises any exceptions, allowing FastAPI to handle them correctly.
 
-**Changes Made:**
-1. Fixed [src/server/utils/dependencies.py](src/server/utils/dependencies.py):
-   - Added try-except around yield in `get_database_session`
-   - Added try-except around yield in `get_optional_database_session`
-2. Fixed [tests/api/test_anime_endpoints.py](tests/api/test_anime_endpoints.py):
-   - Added mock for `BackgroundLoaderService` to prevent initialization errors
-   - Updated test expectations to match 202 Accepted response status
+**Files Modified:**
+1. [src/server/utils/dependencies.py](src/server/utils/dependencies.py) - Fixed exception handling in `get_database_session` and `get_optional_database_session`
+2. [tests/unit/test_dependency_exception_handling.py](tests/unit/test_dependency_exception_handling.py) - Created comprehensive unit tests for the fix
+3. [tests/api/test_anime_endpoints.py](tests/api/test_anime_endpoints.py) - Updated to mock BackgroundLoaderService and expect 202 status codes
 
 **Tests:**
-All 16 anime endpoint tests now pass successfully, including validation scenarios that raise HTTPExceptions.
+- ✅ 5 new unit tests for dependency exception handling (all passing)
+- ✅ 16 anime endpoint integration tests (all passing)
+- ✅ Tests verify proper handling of 400, 404, 422 status codes
+- ✅ Tests verify successful requests still work correctly
+
+**Note for Users:**
+If you're experiencing this error on a running server, please **restart the server** to load the fixed code:
+```bash
+# Stop the server (Ctrl+C)
+# Then restart:
+conda run -n AniWorld python -m uvicorn src.server.fastapi_app:app --host 127.0.0.1 --port 8000 --reload
+```
+
+---
+
+## Next Tasks:
+
+No pending tasks at this time.