Feature/feishu receive file (#1608)

* feat(feishu): add channel file materialization hook for inbound messages

- Introduce Channel.receive_file(msg, thread_id) as a base method for file materialization; default is no-op.
- Implement FeishuChannel.receive_file to download files/images from Feishu messages, save to sandbox, and inject virtual paths into msg.text.
- Update ChannelManager to call receive_file for any channel if msg.files is present, enabling downstream model access to user-uploaded files.
- No impact on Slack/Telegram or other channels (they inherit the default no-op).

* style(backend): format code with ruff for lint compliance

- Auto-formatted packages/harness/deerflow/agents/factory.py and tests/test_create_deerflow_agent.py using `ruff format`
- Ensured both files conform to project linting standards
- Fixes CI lint check failures caused by code style issues

* fix(feishu): handle file write operation asynchronously to prevent blocking

* fix(feishu): rename GetMessageResourceRequest to _GetMessageResourceRequest and remove redundant code

* test(feishu): add tests for receive_file method and placeholder replacement

* fix(manager): remove unnecessary type casting for channel retrieval

* fix(feishu): update logging messages to reflect resource handling instead of image

* fix(feishu): sanitize filename by replacing invalid characters in file uploads

* fix(feishu): improve filename sanitization and reorder image key handling in message processing

* fix(feishu): add thread lock to prevent filename conflicts during file downloads

* fix(test): correct bad merge in test_feishu_parser.py

* chore: run ruff and apply formatting cleanup
fix(feishu): preserve rich-text attachment order and improve fallback filename handling

backend/tests/test_channels.py

@@ -414,6 +414,62 @@ def _make_async_iterator(items):
 
 
 class TestChannelManager:
+    def test_handle_chat_calls_channel_receive_file_for_inbound_files(self, monkeypatch):
+        from app.channels.manager import ChannelManager
+
+        async def go():
+            bus = MessageBus()
+            store = ChannelStore(path=Path(tempfile.mkdtemp()) / "store.json")
+            manager = ChannelManager(bus=bus, store=store)
+
+            outbound_received = []
+
+            async def capture_outbound(msg):
+                outbound_received.append(msg)
+
+            bus.subscribe_outbound(capture_outbound)
+
+            mock_client = _make_mock_langgraph_client()
+            manager._client = mock_client
+
+            modified_msg = InboundMessage(
+                channel_name="test",
+                chat_id="chat1",
+                user_id="user1",
+                text="with /mnt/user-data/uploads/demo.png",
+                files=[{"image_key": "img_1"}],
+            )
+            mock_channel = MagicMock()
+            mock_channel.receive_file = AsyncMock(return_value=modified_msg)
+            mock_service = MagicMock()
+            mock_service.get_channel.return_value = mock_channel
+            monkeypatch.setattr("app.channels.service.get_channel_service", lambda: mock_service)
+
+            await manager.start()
+
+            inbound = InboundMessage(
+                channel_name="test",
+                chat_id="chat1",
+                user_id="user1",
+                text="hi [image]",
+                files=[{"image_key": "img_1"}],
+            )
+            await bus.publish_inbound(inbound)
+            await _wait_for(lambda: len(outbound_received) >= 1)
+            await manager.stop()
+
+            mock_channel.receive_file.assert_awaited_once()
+            called_msg, called_thread_id = mock_channel.receive_file.await_args.args
+            assert called_msg.text == "hi [image]"
+            assert isinstance(called_thread_id, str)
+            assert called_thread_id
+
+            mock_client.runs.wait.assert_called_once()
+            run_call_args = mock_client.runs.wait.call_args
+            assert run_call_args[1]["input"]["messages"][0]["content"] == "with /mnt/user-data/uploads/demo.png"
+
+        _run(go())
+
     def test_handle_chat_creates_thread(self):
         from app.channels.manager import ChannelManager