Add engine accessor to SQLAlchemySession for closing it when it's created from a URL

src/agents/extensions/memory/sqlalchemy_session.py

@@ -319,3 +319,16 @@ async def clear_session(self) -> None:
                 await sess.execute(
                     delete(self._sessions).where(self._sessions.c.session_id == self.session_id)
                 )
+
+    @property
+    def engine(self) -> AsyncEngine:
+        """Access the underlying SQLAlchemy AsyncEngine.
+
+        This property provides direct access to the engine for advanced use cases,
+        such as checking connection pool status, configuring engine settings,
+        or manually disposing the engine when needed.
+
+        Returns:
+            AsyncEngine: The SQLAlchemy async engine instance.
+        """
+        return self._engine

tests/extensions/memory/test_sqlalchemy_session.py

@@ -14,6 +14,7 @@
     Summary,
 )
 from sqlalchemy import select, text, update
+from sqlalchemy.ext.asyncio import AsyncEngine, create_async_engine
 from sqlalchemy.sql import Select
 
 pytest.importorskip("sqlalchemy")  # Skip tests if SQLAlchemy is not installed
@@ -390,3 +391,56 @@ async def recording_execute(statement: Any, *args: Any, **kwargs: Any) -> Any:
 
     assert _item_ids(retrieved_full) == ["rs_first", "msg_second"]
     assert _item_ids(retrieved_limited) == ["rs_first", "msg_second"]
+
+
+async def test_engine_property_from_url():
+    """Test that the engine property returns the AsyncEngine from from_url."""
+    session_id = "engine_property_test"
+    session = SQLAlchemySession.from_url(session_id, url=DB_URL, create_tables=True)
+
+    # Verify engine property returns an AsyncEngine instance
+    assert isinstance(session.engine, AsyncEngine)
+
+    # Verify we can use the engine for advanced operations
+    # For example, check pool status
+    assert session.engine.pool is not None
+
+    # Verify we can manually dispose the engine
+    await session.engine.dispose()
+
+
+async def test_engine_property_from_external_engine():
+    """Test that the engine property returns the external engine."""
+    session_id = "external_engine_test"
+
+    # Create engine externally
+    external_engine = create_async_engine(DB_URL)
+
+    # Create session with external engine
+    session = SQLAlchemySession(session_id, engine=external_engine, create_tables=True)
+
+    # Verify engine property returns the same engine instance
+    assert session.engine is external_engine
+
+    # Verify we can use the engine
+    assert isinstance(session.engine, AsyncEngine)
+
+    # Clean up - user is responsible for disposing external engine
+    await external_engine.dispose()
+
+
+async def test_engine_property_is_read_only():
+    """Test that the engine property cannot be modified."""
+    session_id = "readonly_engine_test"
+    session = SQLAlchemySession.from_url(session_id, url=DB_URL, create_tables=True)
+
+    # Verify engine property exists
+    assert hasattr(session, "engine")
+
+    # Verify it's a property (read-only, cannot be set)
+    # Type ignore needed because mypy correctly detects this is read-only
+    with pytest.raises(AttributeError):
+        session.engine = create_async_engine(DB_URL)  # type: ignore[misc]
+
+    # Clean up
+    await session.engine.dispose()