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/app/channels/manager.py

@@ -675,6 +675,18 @@ class ChannelManager:
             thread_id = await self._create_thread(client, msg)
 
         assistant_id, run_config, run_context = self._resolve_run_params(msg, thread_id)
+
+        # If the inbound message contains file attachments, let the channel
+        # materialize (download) them and update msg.text to include sandbox file paths.
+        # This enables downstream models to access user-uploaded files by path.
+        # Channels that do not support file download will simply return the original message.
+        if msg.files:
+            from .service import get_channel_service
+
+            service = get_channel_service()
+            channel = service.get_channel(msg.channel_name) if service else None
+            logger.info("[Manager] preparing receive file context for %d attachments", len(msg.files))
+            msg = await channel.receive_file(msg, thread_id) if channel else msg
         if extra_context:
             run_context.update(extra_context)