Fix get_driver_connection to return underlying connection

Return connection._connection (the raw dqlite async connection) instead
of the AsyncAdaptedConnection wrapper.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: antoineleclair

src/sqlalchemydqlite/aio.py

@@ -151,8 +151,8 @@ def connect(self, *cargs: Any, **cparams: Any) -> Any:
         return AsyncAdaptedConnection(raw_conn)
 
     def get_driver_connection(self, connection: Any) -> Any:
-        """Return the driver-level connection."""
-        return connection
+        """Return the underlying driver-level connection."""
+        return connection._connection
 
 
 # Register the dialect

tests/test_dialect.py

@@ -136,6 +136,22 @@ def test_parses_version_string(self) -> None:
         assert result == (3, 39, 4)
 
 
+class TestGetDriverConnection:
+    def test_async_dialect_returns_underlying_connection(self) -> None:
+        """get_driver_connection should return the raw connection, not the adapter."""
+        from unittest.mock import MagicMock
+
+        dialect = DqliteDialect_aio()
+        mock_adapted = MagicMock()
+        mock_adapted._connection = MagicMock(name="raw_async_connection")
+
+        result = dialect.get_driver_connection(mock_adapted)
+        assert result is mock_adapted._connection, (
+            "get_driver_connection should unwrap to the underlying connection, "
+            "not return the AsyncAdaptedConnection wrapper"
+        )
+
+
 class TestURLParsing:
     def test_parse_basic_url(self) -> None:
         url = URL.create("dqlite", host="localhost", port=9001, database="test")