fix: 修复浏览器池任务丢失和统计错误 bug

问题:
1. 当浏览器创建失败时，failed_tasks 增加但 total_tasks 不增加
   导致统计显示 "0/5" 这种不合理数据
2. 浏览器创建失败时任务直接丢失，没有重新分配给其他 Worker

修复:
- 添加本地浏览器创建重试（最多2次）
- 失败任务根据 retry_count 决定是否重新入队
- retry_count < 1 时重新入队让其他 Worker 处理
- retry_count >= 1 时才真正失败并计入统计
- 任务字典新增 retry_count 字段初始化为 0
- 添加回归测试用例

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

browser_pool_worker.py

@@ -170,9 +170,36 @@ class BrowserWorker(threading.Thread):
                     break
 
                 # 按需创建或确保浏览器可用
-                if not self._ensure_browser():
+                browser_ready = False
+                for attempt in range(2):
+                    if self._ensure_browser():
+                        browser_ready = True
+                        break
+                    if attempt < 1:
+                        self.log("浏览器创建失败，重试...")
+                        time.sleep(0.5)
+
+                if not browser_ready:
+                    retry_count = int(task.get("retry_count", 0) or 0) if isinstance(task, dict) else 0
+                    if retry_count < 1 and isinstance(task, dict):
+                        task["retry_count"] = retry_count + 1
+                        try:
+                            self.task_queue.put(task, timeout=1)
+                            self.log("浏览器不可用，任务重新入队")
+                        except queue.Full:
+                            self.log("任务队列已满，无法重新入队，任务失败")
+                            callback = task.get("callback")
+                            if callable(callback):
+                                callback(None, "浏览器不可用")
+                            self.total_tasks += 1
+                            self.failed_tasks += 1
+                        continue
+
                     self.log("浏览器不可用，任务失败")
-                    task['callback'](None, "浏览器不可用")
+                    callback = task.get("callback") if isinstance(task, dict) else None
+                    if callable(callback):
+                        callback(None, "浏览器不可用")
+                    self.total_tasks += 1
                     self.failed_tasks += 1
                     continue
 
@@ -319,7 +346,8 @@ class BrowserWorkerPool:
             'func': task_func,
             'args': args,
             'kwargs': kwargs,
-            'callback': callback
+            'callback': callback,
+            'retry_count': 0,
         }
 
         try:

tests/test_browser_pool_worker.py

@@ -0,0 +1,75 @@
+from __future__ import annotations
+
+import queue
+
+from browser_pool_worker import BrowserWorker
+
+
+class _AlwaysFailEnsureWorker(BrowserWorker):
+    def __init__(self, *, worker_id: int, task_queue: queue.Queue):
+        super().__init__(worker_id=worker_id, task_queue=task_queue, pre_warm=False)
+        self.ensure_calls = 0
+
+    def _ensure_browser(self) -> bool:  # noqa: D401 - matching base naming
+        self.ensure_calls += 1
+        if self.ensure_calls >= 2:
+            self.running = False
+        return False
+
+    def _close_browser(self):
+        self.browser_instance = None
+
+
+def test_requeue_task_when_browser_unavailable():
+    task_queue: queue.Queue = queue.Queue()
+    callback_calls: list[tuple[object, object]] = []
+
+    def callback(result, error):
+        callback_calls.append((result, error))
+
+    task = {
+        "func": lambda *_args, **_kwargs: None,
+        "args": (),
+        "kwargs": {},
+        "callback": callback,
+        "retry_count": 0,
+    }
+
+    worker = _AlwaysFailEnsureWorker(worker_id=1, task_queue=task_queue)
+    worker.start()
+    task_queue.put(task)
+    worker.join(timeout=5)
+
+    assert worker.is_alive() is False
+    assert worker.ensure_calls == 2  # 本地最多尝试2次创建浏览器
+    assert callback_calls == []  # 第一次失败会重新入队，不应立即回调失败
+
+    requeued = task_queue.get_nowait()
+    assert requeued["retry_count"] == 1
+
+
+def test_fail_task_after_second_assignment():
+    task_queue: queue.Queue = queue.Queue()
+    callback_calls: list[tuple[object, object]] = []
+
+    def callback(result, error):
+        callback_calls.append((result, error))
+
+    task = {
+        "func": lambda *_args, **_kwargs: None,
+        "args": (),
+        "kwargs": {},
+        "callback": callback,
+        "retry_count": 1,  # 已重新分配过1次
+    }
+
+    worker = _AlwaysFailEnsureWorker(worker_id=1, task_queue=task_queue)
+    worker.start()
+    task_queue.put(task)
+    worker.join(timeout=5)
+
+    assert worker.is_alive() is False
+    assert callback_calls == [(None, "浏览器不可用")]
+    assert worker.total_tasks == 1
+    assert worker.failed_tasks == 1
+