Harden production workflows and agent admission

server/monlet_server/db.py

@@ -17,7 +17,17 @@ def get_engine() -> AsyncEngine:
     global _engine, _sessionmaker
     if _engine is None:
         s = get_settings()
-        _engine = create_async_engine(s.database_url, pool_pre_ping=True, future=True)
+        # PH-016: explicit pool sizing. pool_pre_ping protects against stale
+        # connections after PG restarts; pool_recycle bounds connection age.
+        _engine = create_async_engine(
+            s.database_url,
+            pool_pre_ping=True,
+            pool_size=s.db_pool_size,
+            max_overflow=s.db_max_overflow,
+            pool_timeout=s.db_pool_timeout_sec,
+            pool_recycle=s.db_pool_recycle_sec,
+            future=True,
+        )
         _sessionmaker = async_sessionmaker(_engine, expire_on_commit=False)
     return _engine