feat：接入sse

app/common/sse.py

@@ -0,0 +1,65 @@
+"""SSE 编码和连接生命周期，不保存全局任务队列"""
+
+import json
+from contextlib import aclosing
+
+import anyio
+from starlette.responses import StreamingResponse
+
+from app.common.response import error_content, success_response
+from app.core.exceptions import BizException, handle_unexpected_exception
+
+
+def pack_event(event, content):
+    return f"event: {event}\ndata: {json.dumps(content, ensure_ascii=False)}\n\n"
+
+
+async def encode_events(service, execution, request):
+    try:
+        async with aclosing(service.stream(*execution)) as events:
+            async for event, data in events:
+                yield pack_event(event, success_response(data).model_dump(mode="json"))
+    except BizException as exc:
+        yield pack_event("error", error_content(exc.code, exc.msg))
+    except Exception as exc:  # noqa: BLE001 流中异常统一封装后终止
+        # 流开始后不能修改 HTTP 状态，复用统一异常映射并发送终止事件
+        exc._agent_thread_id = execution[0]
+        response = await handle_unexpected_exception(request, exc)
+        yield pack_event("error", json.loads(response.body))
+
+
+class AgentEventResponse(StreamingResponse):
+    media_type = "text/event-stream"
+
+    def __init__(self, service, execution, request):
+        self.service = service
+        self.execution = execution
+        super().__init__(
+            encode_events(service, execution, request),
+            media_type="text/event-stream",
+            headers={"Cache-Control": "no-cache", "X-Accel-Buffering": "no"},
+        )
+
+    async def stream_response(self, send):
+        try:
+            await super().stream_response(send)
+        finally:
+            # 在消费流的同一协程关闭生成器，避免追踪上下文跨协程退出
+            with anyio.CancelScope(shield=True):
+                await self.body_iterator.aclose()
+
+    async def __call__(self, scope, receive, send):
+        try:
+            # 同时监听断开连接，模型尚未产生下一个事件时也能及时取消
+            async with anyio.create_task_group() as group:
+
+                async def stream():
+                    await self.stream_response(send)
+                    group.cancel_scope.cancel()
+
+                group.start_soon(stream)
+                await self.listen_for_disconnect(receive)
+                group.cancel_scope.cancel()
+        finally:
+            # 即使连接在生成器开始前断开，也要释放预先占用的任务
+            self.service.release(self.execution[0])