fix: disable autoconnect and set pool timeout on PooledPostgresqlDatabase (#80)

- Set timeout=5 so pool exhaustion surfaces as an error instead of hanging forever
- Set autoconnect=False to require explicit connection acquisition
- Add HTTP middleware in main.py to open/close connections per request

Closes #80

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/db_engine.py

@@ -30,8 +30,8 @@ if DATABASE_TYPE.lower() == "postgresql":
         port=int(os.environ.get("POSTGRES_PORT", "5432")),
         max_connections=20,
         stale_timeout=300,  # 5 minutes
-        timeout=0,
+        timeout=5,
-        autoconnect=True,
+        autoconnect=False,
         autorollback=True,  # Automatically rollback failed transactions
     )
 else:

app/main.py

@@ -8,6 +8,8 @@ from fastapi import Depends, FastAPI, Request
 from fastapi.openapi.docs import get_swagger_ui_html
 from fastapi.openapi.utils import get_openapi
 
+from .db_engine import db
+
 # from fastapi.openapi.docs import get_swagger_ui_html
 # from fastapi.openapi.utils import get_openapi
 
@@ -68,6 +70,17 @@ app = FastAPI(
 )
 
 
+@app.middleware("http")
+async def db_connection_middleware(request: Request, call_next):
+    db.connect(reuse_if_open=True)
+    try:
+        response = await call_next(request)
+    finally:
+        if not db.is_closed():
+            db.close()
+    return response
+
+
 logger.info(f"Starting up now...")