feat(agent-service): 添加直接模式下的消息处理支持

当代理服务处于非运行状态时，现在会使用process_direct方法来处理入站消息，
而不是依赖submit_direct方法。这使得服务能够在两种模式下都能正确处理消息。

添加了新的DirectModeInboundService和RunningInboundService测试类来验证
不同模式下的行为，并增加了相应的集成测试用例。

app-instance/backend/beaver/services/agent_service.py

@@ -1285,7 +1285,8 @@ class AgentService:
 
         channel_identity = inbound.channel_identity
         try:
-            result = await self.submit_direct(
+            runner = self.submit_direct if self.is_running else self.process_direct
+            result = await runner(
                 inbound.content,
                 session_id=inbound.session_id,
                 source=f"gateway:{inbound.channel}",

app-instance/backend/tests/unit/test_gateway_channels.py

@@ -53,6 +53,27 @@ class InvalidService:
     is_running = True
 
 
+class DirectModeInboundService(AgentService):
+    @property
+    def is_running(self) -> bool:
+        return False
+
+    async def submit_direct(self, message: str, **kwargs: Any) -> FakeResult:
+        raise RuntimeError("AgentLoop.submit_direct() requires an active run() loop")
+
+    async def process_direct(self, message: str, **kwargs: Any) -> FakeResult:
+        return FakeResult(
+            session_id=kwargs.get("session_id") or "s1",
+            output_text=f"direct:{message}",
+        )
+
+
+class RunningInboundService(AgentService):
+    @property
+    def is_running(self) -> bool:
+        return True
+
+
 def test_gateway_routes_memory_channel_roundtrip(tmp_path) -> None:
     async def run() -> None:
         bus = MessageBus()
@@ -197,7 +218,7 @@ def test_gateway_fails_fast_for_service_without_handle_inbound_message() -> None
 
 def test_agent_service_maps_inbound_error_to_structured_outbound() -> None:
     async def run() -> None:
-        service = AgentService()
+        service = RunningInboundService()
 
         async def failing_submit_direct(message: str, **kwargs: Any) -> FakeResult:
             raise RuntimeError("boom")
@@ -217,7 +238,7 @@ def test_agent_service_maps_inbound_error_to_structured_outbound() -> None:
 
 def test_agent_service_maps_stopped_runtime_to_stopped_outbound() -> None:
     async def run() -> None:
-        service = AgentService()
+        service = RunningInboundService()
 
         async def stopped_submit_direct(message: str, **kwargs: Any) -> FakeResult:
             raise RuntimeError("AgentLoop.submit_direct() is not accepting new tasks after stop()")
@@ -233,6 +254,19 @@ def test_agent_service_maps_stopped_runtime_to_stopped_outbound() -> None:
     asyncio.run(run())
 
 
+def test_agent_service_handles_inbound_in_direct_mode() -> None:
+    async def run() -> None:
+        service = DirectModeInboundService()
+        outbound = await service.handle_inbound_message(
+            InboundMessage(channel="memory", content="hello", session_id="s1")
+        )
+
+        assert outbound.finish_reason == "stop"
+        assert outbound.content == "direct:hello"
+
+    asyncio.run(run())
+
+
 def test_channel_manager_keeps_unknown_channel_outbound_undeliverable() -> None:
     async def run() -> None:
         bus = MessageBus()