feat(cursor): expose PEP 249 optional Cursor.connection attribute

Add a read-only ``connection`` property on both Cursor and AsyncCursor
returning the parent connection. PEP 249's optional DB API extension
section specifies this attribute; downstream libraries (e.g. pooling
layers) expect it to work.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: antoineleclair

src/dqlitedbapi/aio/cursor.py

@@ -31,6 +31,14 @@ def __init__(self, connection: "AsyncConnection") -> None:
         self._closed = False
         self._lastrowid: int | None = None
 
+    @property
+    def connection(self) -> "AsyncConnection":
+        """The AsyncConnection this cursor was created from.
+
+        PEP 249 optional extension. Read-only.
+        """
+        return self._connection
+
     @property
     def description(
         self,

src/dqlitedbapi/cursor.py

@@ -134,6 +134,14 @@ def __init__(self, connection: "Connection") -> None:
         self._closed = False
         self._lastrowid: int | None = None
 
+    @property
+    def connection(self) -> "Connection":
+        """The Connection this Cursor was created from.
+
+        PEP 249 optional extension. Read-only.
+        """
+        return self._connection
+
     @property
     def description(
         self,

tests/test_async_cursor.py

@@ -49,6 +49,11 @@ async def test_close_is_idempotent(self) -> None:
         await cursor.close()  # must not raise
         assert cursor._closed
 
+    def test_connection_property(self) -> None:
+        conn = AsyncConnection("localhost:9001")
+        cursor = AsyncCursor(conn)
+        assert cursor.connection is conn
+
     @pytest.mark.asyncio
     async def test_fetchone_on_closed_cursor_raises(self) -> None:
         conn = AsyncConnection("localhost:9001")

tests/test_cursor.py

@@ -42,6 +42,11 @@ def test_close_is_idempotent(self) -> None:
         cursor.close()  # must not raise
         assert cursor._closed
 
+    def test_connection_property(self) -> None:
+        conn = Connection("localhost:9001")
+        cursor = Cursor(conn)
+        assert cursor.connection is conn
+
     def test_fetchone_on_closed_cursor_raises(self) -> None:
         conn = Connection("localhost:9001")
         cursor = Cursor(conn)