fix(redis): 修复 Redis 流读取兼容性问题

- 支持 bytes 和 str 类型的 entry_id
- 支持 list 类型响应格式
- 优化 payload 解码处理

backend/tests/integration/v1/agent/test_routes.py

@@ -110,6 +110,18 @@ class _FakeAgentService:
         }
 
 
+class _FailingStreamAgentService(_FakeAgentService):
+    async def stream_events(
+        self,
+        *,
+        thread_id: str,
+        last_event_id: str | None,
+        current_user: CurrentUser,
+    ) -> list[dict[str, object]]:
+        del thread_id, last_event_id, current_user
+        raise RuntimeError("redis timeout")
+
+
 def test_run_requires_auth_and_returns_202_task_id() -> None:
     app.dependency_overrides[get_agent_service] = lambda: _FakeAgentService()
     client = TestClient(app)
@@ -197,6 +209,38 @@ def test_stream_reads_from_last_event_id() -> None:
         app.dependency_overrides = {}
 
 
+def test_stream_handles_stream_backend_errors_without_connection_crash() -> None:
+    app.dependency_overrides[get_agent_service] = lambda: _FailingStreamAgentService()
+    app.dependency_overrides[get_current_user] = lambda: CurrentUser(
+        id=uuid4(), email="user@example.com"
+    )
+    client = TestClient(app)
+    original_acquire = agent_router._acquire_sse_slot
+    original_release = agent_router._release_sse_slot
+
+    async def _allow_slot(*, user_id: str) -> bool:
+        del user_id
+        return True
+
+    async def _noop_release(*, user_id: str) -> None:
+        del user_id
+        return None
+
+    agent_router._acquire_sse_slot = _allow_slot  # type: ignore[assignment]
+    agent_router._release_sse_slot = _noop_release  # type: ignore[assignment]
+
+    try:
+        response = client.get(
+            "/api/v1/agent/runs/00000000-0000-0000-0000-000000000001/events?idle_limit=1"
+        )
+        assert response.status_code == 200
+        assert response.headers["content-type"].startswith("text/event-stream")
+    finally:
+        agent_router._acquire_sse_slot = original_acquire  # type: ignore[assignment]
+        agent_router._release_sse_slot = original_release  # type: ignore[assignment]
+        app.dependency_overrides = {}
+
+
 def test_stream_rejects_invalid_last_event_id() -> None:
     app.dependency_overrides[get_agent_service] = lambda: _FakeAgentService()
     app.dependency_overrides[get_current_user] = lambda: CurrentUser(