feat(edge): 截图响应改为HTTP回调，COS使用预签名URL

- 截图完成后优先通过HTTP回调WVP返回结果，回调失败降级写Redis
- COS上传后生成预签名URL（1小时有效期），不附加额外Params
- 移除Edge端缓存逻辑（缓存由WVP端统一管理）

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

core/screenshot_handler.py

@@ -2,7 +2,8 @@
 截图处理模块 - 监听云端 Redis Stream 截图请求，截图后上传 COS
 
 数据流：
-  WVP → XADD edge_snap_request → Edge 消费 → capture frame → upload COS → SET snap:result:{id}
+  WVP → XADD edge_snap_request → Edge 消费 → capture frame → upload COS → HTTP 回调 WVP
+  （回调失败时降级写 Redis snap:result:{id}）
 """
 
 import io
@@ -15,6 +16,7 @@ from typing import Optional
 
 import cv2
 import numpy as np
+import requests
 
 from config.settings import get_settings, COSConfig
 
@@ -25,16 +27,19 @@ SNAP_REQUEST_STREAM = "edge_snap_request"
 SNAP_CONSUMER_GROUP = "edge_snap_group"
 SNAP_CONSUMER_NAME = "edge_snap_worker"
 SNAP_RESULT_KEY_PREFIX = "snap:result:"
-SNAP_CACHE_KEY_PREFIX = "snap:cache:"
+SNAP_RESULT_TTL = 60       # 降级结果 key 60s 过期
-SNAP_RESULT_TTL = 60       # 结果 key 60s 过期
+
-SNAP_CACHE_TTL = 300        # 缓存 key 5min 过期
+# HTTP 回调
+SNAP_CALLBACK_PATH = "/api/ai/roi/snap/callback"
+SNAP_CALLBACK_TIMEOUT = 5  # 回调 HTTP 超时（秒）
 
 
 class ScreenshotHandler:
     """截图处理器
 
     从云端 Redis Stream 消费截图请求，通过 MultiStreamManager 获取最新帧，
-    JPEG 编码后直传 COS，最后将结果 URL 写回 Redis。
+    JPEG 编码后直传 COS，最后通过 HTTP 回调 WVP 返回结果 URL。
+    回调失败时降级写 Redis。
     """
 
     def __init__(self, cloud_redis, stream_manager):
@@ -166,20 +171,25 @@ class ScreenshotHandler:
         request_id = fields.get("request_id", "")
         camera_code = fields.get("camera_code", "")
         cos_path = fields.get("cos_path", "")
+        callback_url = fields.get("callback_url", "")
 
         if not request_id or not camera_code or not cos_path:
             logger.warning("[截图] 请求字段不完整: %s", fields)
-            self._write_result(request_id, {"status": "error", "message": "请求字段不完整"})
+            self._send_result(callback_url, request_id, camera_code, {
+                "status": "error",
+                "message": "请求字段不完整",
+            })
             return
 
-        logger.info("[截图] 收到截图请求: request_id=%s, camera=%s", request_id, camera_code)
+        logger.info("[截图] 收到截图请求: request_id=%s, camera=%s, callback=%s",
+                    request_id, camera_code, callback_url or "(无)")
 
         # 1. 抓帧
         jpeg_bytes = self._capture_frame(camera_code)
         if jpeg_bytes is None:
-            self._write_result(request_id, {
+            self._send_result(callback_url, request_id, camera_code, {
                 "status": "error",
-                "message": f"摄像头流未连接: {camera_code}"
+                "message": f"摄像头流未连接: {camera_code}",
             })
             return
 
@@ -191,23 +201,17 @@ class ScreenshotHandler:
             url = self._upload_to_cos(jpeg_bytes, cos_path)
 
         if url is None:
-            self._write_result(request_id, {
+            self._send_result(callback_url, request_id, camera_code, {
                 "status": "error",
-                "message": "COS 上传失败"
+                "message": "COS 上传失败",
             })
             return
 
-        # 3. 写结果
+        # 3. 发送结果
-        result = {"status": "ok", "url": url}
+        self._send_result(callback_url, request_id, camera_code, {
-        self._write_result(request_id, result)
+            "status": "ok",
-
+            "url": url,
-        # 4. 写缓存
+        })
-        cache_key = SNAP_CACHE_KEY_PREFIX + camera_code
-        cache_data = json.dumps({"url": url, "timestamp": int(time.time())})
-        try:
-            self._cloud_redis.set(cache_key, cache_data, ex=SNAP_CACHE_TTL)
-        except Exception as e:
-            logger.warning("[截图] 写入缓存失败: %s", e)
 
         logger.info("[截图] 截图完成: camera=%s, url=%s", camera_code, url)
 
@@ -247,8 +251,11 @@ class ScreenshotHandler:
 
     # ==================== COS 上传 ====================
 
+    # 预签名 URL 有效期（秒），必须大于 WVP 缓存 TTL（300s）
+    PRESIGNED_URL_EXPIRES = 3600
+
     def _upload_to_cos(self, jpeg_bytes: bytes, cos_path: str) -> Optional[str]:
-        """上传 JPEG 到 COS，返回访问 URL"""
+        """上传 JPEG 到 COS，返回预签名访问 URL"""
         if not self._cos_client:
             logger.error("[截图] COS 客户端未初始化")
             return None
@@ -261,22 +268,53 @@ class ScreenshotHandler:
                 Key=cos_path,
                 ContentType="image/jpeg",
             )
-            url = "https://{}.cos.{}.myqcloud.com/{}".format(
+            # 生成预签名 URL（不附加额外 Params，保持 URL 简洁）
-                self._cos_config.bucket, self._cos_config.region, cos_path
+            url = self._cos_client.get_presigned_url(
+                Method="GET",
+                Bucket=self._cos_config.bucket,
+                Key=cos_path,
+                Expired=self.PRESIGNED_URL_EXPIRES,
             )
             return url
         except Exception as e:
             logger.error("[截图] COS 上传失败: %s", e)
             return None
 
-    # ==================== Redis 结果 ====================
+    # ==================== 结果发送（回调 + 降级） ====================
 
-    def _write_result(self, request_id: str, data: dict):
+    def _send_result(self, callback_url: str, request_id: str, camera_code: str, data: dict):
-        """将结果写入 Redis key（TTL 60s）"""
+        """发送截图结果：优先 HTTP 回调，失败则降级写 Redis"""
         if not request_id:
             return
+
+        # 构造回调 body
+        body = {
+            "request_id": request_id,
+            "camera_code": camera_code,
+            **data,
+        }
+
+        # 优先尝试 HTTP 回调
+        if callback_url:
+            try:
+                url = callback_url.rstrip("/") + SNAP_CALLBACK_PATH
+                resp = requests.post(url, json=body, timeout=SNAP_CALLBACK_TIMEOUT)
+                if resp.status_code < 300:
+                    logger.info("[截图] HTTP 回调成功: request_id=%s", request_id)
+                    return
+                else:
+                    logger.warning("[截图] HTTP 回调返回 %d: request_id=%s", resp.status_code, request_id)
+            except Exception as e:
+                logger.warning("[截图] HTTP 回调失败: %s, 降级写 Redis", e)
+
+        # 降级：写 Redis result key
+        self._write_result_redis(request_id, body)
+
+    def _write_result_redis(self, request_id: str, data: dict):
+        """降级：将结果写入 Redis key（TTL 60s）"""
         key = SNAP_RESULT_KEY_PREFIX + request_id
         try:
             self._cloud_redis.set(key, json.dumps(data), ex=SNAP_RESULT_TTL)
+            logger.info("[截图] 降级写 Redis 成功: request_id=%s", request_id)
         except Exception as e:
-            logger.error("[截图] 写入结果失败: %s", e)
+            logger.error("[截图] 降级写 Redis 也失败: %s", e)