Here's your plan:

# GET /healthz Endpoint Implementation Plan

## Context

The FastAPI app (`src/my_deepagent/api/app.py`) uses:
- **Database**: Singleton `Database` instance stored in `app.state.db` during lifespan startup
- **Dependency injection**: `deps.get_db(request)` retrieves the shared DB instance
- **Router pattern**: API routes are organized as separate modules in `src/my_deepagent/api/routes/` and included via `app.include_router()`
- **Async/await**: All database operations are async (SQLAlchemy AsyncSession)
- **Response format**: JSON responses via Pydantic models or dicts

## Phases

1. Create response model in `api/models.py` with `status` (str) and `db` (bool) fields.
2. Create new route module `api/routes/health.py` with `GET /healthz` endpoint.
3. Endpoint executes `SELECT 1` via `db.session()` to test connectivity; catches exceptions.
4. Include health router in `app.py` with prefix `/api/health` (or `/healthz` directly).
5. Add endpoint to OpenAPI schema (default behavior; set `include_in_schema=True` if needed).
6. Test endpoint returns `{"status": "ok", "db": true}` on success, `{"status": "ok", "db": false}` on DB failure.

## Verification

- **Unit test**: Mock `Database`, verify response structure and `db` field logic.
- **Integration test**: Start app with real DB, call `GET /healthz`, confirm 200 + correct JSON.
- **Failure case**: Simulate DB unavailability (e.g., wrong connection string), verify `db: false` returned.
- **Schema check**: Confirm endpoint appears in OpenAPI docs at `/docs`.