feat: Phase 3 - parallel execution, progress reporting, result caching + AgentChat bug fixes

Phase 3 能力:
- DAG 并行执行 (workflow_engine): asyncio.gather 并行执行就绪节点
- Debate 并行 (orchestrator): for 循环改为 asyncio.gather
- 粒度进度上报 (workflow_engine + tasks + websocket): Redis 推送 + DB 降级
- 工具结果缓存 (tool_manager): 确定性工具默认开启缓存
- LLM 响应缓存 (core): messages[-4:] + model 哈希，5min TTL

AgentChat bug 修复 (Gitea #1-#5):
- #1 SSE 降级重复空消息: fallback POST 前移除占位消息
- #2 streamTimeout 泄漏: while 正常退出后 clearTimeout
- #3 loading 闪烁: final/error 事件中提前设 loading=false
- #4 SSE 事件类型对齐: 确认匹配，未知类型加 console.warn
- #5 retryMessage 流式残留: 重试时清理占位消息

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/app/api/websocket.py

@@ -13,6 +13,20 @@ import asyncio
 router = APIRouter()
 
 
+def _get_progress_from_redis(execution_id: str) -> Optional[dict]:
+    """从 Redis 读取进度数据。"""
+    try:
+        from app.core.redis_client import get_redis_client
+        redis_client = get_redis_client()
+        if redis_client:
+            raw = redis_client.get(f"workflow:progress:{execution_id}")
+            if raw:
+                return json.loads(raw)
+    except Exception:
+        pass
+    return None
+
+
 @router.websocket("/api/v1/ws/executions/{execution_id}")
 async def websocket_execution_status(
     websocket: WebSocket,
@@ -21,31 +35,36 @@ async def websocket_execution_status(
 ):
     """
     WebSocket实时推送执行状态
-    
+
     Args:
         websocket: WebSocket连接
         execution_id: 执行记录ID
         token: JWT Token（可选，通过query参数传递）
     """
-    # 验证token（可选，如果需要认证）
-    # user = await get_current_user_optional(token)
-    
-    # 建立连接
     await websocket_manager.connect(websocket, execution_id)
-    
+
     db = SessionLocal()
-    
+
     try:
         # 发送初始状态
         execution = db.query(Execution).filter(Execution.id == execution_id).first()
         if execution:
-            await websocket_manager.send_personal_message({
-                "type": "status",
-                "execution_id": execution_id,
-                "status": execution.status,
-                "progress": 0,
-                "message": "连接已建立"
-            }, websocket)
+            # 尝试从 Redis 读取进度
+            redis_progress = _get_progress_from_redis(execution_id)
+            if redis_progress:
+                await websocket_manager.send_personal_message({
+                    "type": "progress",
+                    "execution_id": execution_id,
+                    **redis_progress,
+                }, websocket)
+            else:
+                await websocket_manager.send_personal_message({
+                    "type": "status",
+                    "execution_id": execution_id,
+                    "status": execution.status,
+                    "progress": 0,
+                    "message": "连接已建立"
+                }, websocket)
         else:
             await websocket_manager.send_personal_message({
                 "type": "error",
@@ -53,30 +72,56 @@ async def websocket_execution_status(
             }, websocket)
             await websocket.close()
             return
-        
+
+        last_progress = -1
+
         # 持续监听并推送状态更新
         while True:
             try:
-                # 接收客户端消息（心跳等）
-                data = await websocket.receive_text()
-                
-                # 处理客户端消息
+                # 接收客户端消息（心跳等），超时 1 秒以便轮询进度
                 try:
-                    message = json.loads(data)
-                    if message.get("type") == "ping":
-                        await websocket_manager.send_personal_message({
-                            "type": "pong"
-                        }, websocket)
-                except:
-                    pass
-                
+                    data = await asyncio.wait_for(websocket.receive_text(), timeout=1.0)
+                    try:
+                        message = json.loads(data)
+                        if message.get("type") == "ping":
+                            await websocket_manager.send_personal_message({
+                                "type": "pong"
+                            }, websocket)
+                    except Exception:
+                        pass
+                except asyncio.TimeoutError:
+                    pass  # 超时后轮询进度
+
             except WebSocketDisconnect:
                 break
-            
-            # 检查执行状态
-            db.refresh(execution)
-            
+
+            # 优先从 Redis 读取进度（推送模式）
+            redis_progress = _get_progress_from_redis(execution_id)
+            if redis_progress:
+                pct = redis_progress.get("progress", -1)
+                if pct != last_progress:
+                    last_progress = pct
+                    await websocket_manager.send_personal_message({
+                        "type": "progress",
+                        "execution_id": execution_id,
+                        **redis_progress,
+                    }, websocket)
+            else:
+                # Redis 不可用时回退到 DB 轮询
+                db.refresh(execution)
+                pct = 100 if execution.status in ["completed", "failed"] else (50 if execution.status == "running" else 0)
+                if pct != last_progress:
+                    last_progress = pct
+                    await websocket_manager.send_personal_message({
+                        "type": "status",
+                        "execution_id": execution_id,
+                        "status": execution.status,
+                        "progress": pct,
+                        "message": f"执行中..." if execution.status == "running" else "等待执行"
+                    }, websocket)
+
             # 如果执行完成或失败，发送最终状态并断开
+            db.refresh(execution)
             if execution.status in ["completed", "failed"]:
                 await websocket_manager.send_personal_message({
                     "type": "status",
@@ -87,24 +132,10 @@ async def websocket_execution_status(
                     "error": execution.error_message if execution.status == "failed" else None,
                     "execution_time": execution.execution_time
                 }, websocket)
-                
-                # 等待一下再断开，确保客户端收到消息
+
                 await asyncio.sleep(1)
                 break
-            
-            # 定期发送状态更新（每2秒）
-            await asyncio.sleep(2)
-            
-            # 重新查询执行状态
-            db.refresh(execution)
-            await websocket_manager.send_personal_message({
-                "type": "status",
-                "execution_id": execution_id,
-                "status": execution.status,
-                "progress": 50 if execution.status == "running" else 0,
-                "message": f"执行中..." if execution.status == "running" else "等待执行"
-            }, websocket)
-    
+
     except WebSocketDisconnect:
         pass
     except Exception as e:
@@ -114,7 +145,7 @@ async def websocket_execution_status(
                 "type": "error",
                 "message": f"发生错误: {str(e)}"
             }, websocket)
-        except:
+        except Exception:
             pass
     finally:
         websocket_manager.disconnect(websocket, execution_id)