feat(message-processing-status): unified processing status indicator for Telegram, Slack, Discord, Feishu

- Add ChannelCapability.PROCESSING_STATUS and capability detection for supported channels
- Implement mark_message_processing_started/finished in Telegram, Slack, Discord, Feishu modules
  - Telegram: manage typing lifecycle with max duration and explicit stop
  - Slack: add/remove reaction as processing indicator
  - Discord: start/stop typing indicator with async task management
  - Feishu: add/remove reaction for processing status
- Refactor message chain to invoke processing status hooks for supported channels
- Ensure processing status is properly finished on sync and async message handling paths
- Add tests for processing status lifecycle and capability detection across channels

tests/test_message_processing_status.py

@@ -0,0 +1,153 @@
+import json
+import unittest
+from types import SimpleNamespace
+from unittest.mock import MagicMock, patch
+
+from app.agent import _finish_processing_status
+from app.modules.discord import DiscordModule
+from app.modules.slack import SlackModule
+from app.schemas.message import ChannelCapability, ChannelCapabilityManager
+from app.schemas.types import MessageChannel
+
+
+class TestMessageProcessingStatus(unittest.TestCase):
+    def test_processing_status_capability_only_enabled_for_supported_channels(self):
+        supported = {
+            MessageChannel.Telegram,
+            MessageChannel.Feishu,
+            MessageChannel.Slack,
+            MessageChannel.Discord,
+        }
+
+        for channel in MessageChannel:
+            self.assertEqual(
+                ChannelCapabilityManager.supports_capability(
+                    channel, ChannelCapability.PROCESSING_STATUS
+                ),
+                channel in supported,
+            )
+
+    def test_slack_processing_status_uses_reaction(self):
+        module = SlackModule()
+        module._channel = MessageChannel.Slack
+        client = MagicMock()
+        client.add_reaction.return_value = True
+        client.remove_reaction.return_value = True
+
+        with (
+            patch.object(
+                module, "get_config", return_value=SimpleNamespace(name="slack-main")
+            ),
+            patch.object(module, "get_instance", return_value=client),
+        ):
+            status = module.mark_message_processing_started(
+                channel=MessageChannel.Slack,
+                source="slack-main",
+                userid="U01",
+                message_id="1710000000.000100",
+                chat_id="C01",
+                text="hello",
+            )
+            removed = module.mark_message_processing_finished(
+                channel=MessageChannel.Slack,
+                source="slack-main",
+                userid="U01",
+                status=status,
+            )
+
+        client.add_reaction.assert_called_once_with(
+            channel="C01",
+            timestamp="1710000000.000100",
+            emoji="eyes",
+        )
+        client.remove_reaction.assert_called_once_with(
+            channel="C01",
+            timestamp="1710000000.000100",
+            emoji="eyes",
+        )
+        self.assertEqual(status["metadata"]["kind"], "reaction")
+        self.assertTrue(removed)
+
+    def test_slack_parser_exposes_message_location_for_reaction_status(self):
+        module = SlackModule()
+
+        with patch.object(
+            module, "get_config", return_value=SimpleNamespace(name="slack-main")
+        ):
+            message = module.message_parser(
+                source="slack-main",
+                body=json.dumps(
+                    {
+                        "type": "message",
+                        "user": "U01",
+                        "text": "hello",
+                        "ts": "1710000000.000100",
+                        "channel": "C01",
+                    }
+                ),
+                form=None,
+                args=None,
+            )
+
+        self.assertEqual(message.message_id, "1710000000.000100")
+        self.assertEqual(message.chat_id, "C01")
+
+    def test_discord_processing_status_starts_and_stops_typing(self):
+        module = DiscordModule()
+        module._channel = MessageChannel.Discord
+        client = MagicMock()
+        client.start_typing.return_value = True
+        client.stop_typing.return_value = True
+
+        with (
+            patch.object(
+                module, "get_config", return_value=SimpleNamespace(name="discord-main")
+            ),
+            patch.object(module, "get_instance", return_value=client),
+        ):
+            status = module.mark_message_processing_started(
+                channel=MessageChannel.Discord,
+                source="discord-main",
+                userid="10001",
+                message_id="20002",
+                chat_id="30003",
+                text="hello",
+            )
+            finished = module.mark_message_processing_finished(
+                channel=MessageChannel.Discord,
+                source="discord-main",
+                userid="10001",
+                status=status,
+            )
+
+        client.start_typing.assert_called_once_with(userid="10001", chat_id="30003")
+        client.stop_typing.assert_called_once_with(userid="10001", chat_id="30003")
+        self.assertEqual(status["metadata"]["kind"], "typing")
+        self.assertTrue(finished)
+
+    def test_agent_finish_processing_status_uses_module_interface(self):
+        status = {
+            "channel": MessageChannel.Telegram.value,
+            "source": "telegram-main",
+            "userid": "10001",
+            "message_id": None,
+            "chat_id": "-100",
+            "metadata": {"kind": "typing"},
+        }
+
+        with patch("app.agent.AgentChain") as chain_cls:
+            _finish_processing_status(status, user_id="fallback")
+
+        chain_cls.return_value.run_module.assert_called_once_with(
+            "mark_message_processing_finished",
+            channel=MessageChannel.Telegram,
+            source="telegram-main",
+            userid="10001",
+            message_id=None,
+            chat_id="-100",
+            status=status,
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()