feat: 浏览器二期后端：远控服务 + ref 快照 + server 代理

- playwright_remote.py（新）：MCP 进程内 Unix socket HTTP 服务，
  监听 worktree/.browser-remote.sock；GET /state、GET /stream
  （SSE 画面流）、POST /input、POST /control（接管/交还）。
  线程契约（实测）：Playwright 同步调用只能在创建页面的线程，
  所以 HTTP 线程只读属性/读最新帧/入队，MCP 主循环用
  select 轮询（50ms） draining 输入并 pump screencast 帧
  （无 ack 则 CDP 首帧后停流）。
- 画面流走 CDP screencast 帧（学 chrome-devtools-mcp），不用
  定时截图；ffmpeg 录像暂不做。
- snapshot_refs/click_ref（学 playwright-mcp 的 ref 机制）+
  mouse_move/key_press/type_text；agent 工具在 holder=user 时
  直接报错，等用户交还。
- server.py：/tasks/{id}/browser/{state,stream,input,control}
  代理到 worktree socket，复用任务鉴权与 worktree 解析；
  会话不存在时 503（轮次结束即消失是设计）。
- 播种器：MCP 脚本是系统文件，版本变化时刷新老租户旧脚本
  （script_refreshed 打日志），否则远控只对新项目生效；
  新增 playwright_remote.py 进播种清单。
- 队列遮蔽修复：cloud/queue.py 会遮蔽 stdlib queue，改用
  SimpleQueue（deque+锁），仓库模式与 flat-copy 两路都通。
- 测试：新 20 项（remote 服务、server 代理、ref/输入/
  screencast fake），全量 1354 项通过（skipped 4）。

cloud/tests/test_playwright.py

@@ -25,6 +25,13 @@ class _FakeLocator:
     def inner_text(self, timeout=None):
         return self._text
 
+    @property
+    def first(self):
+        return self
+
+    def click(self, timeout=None):
+        pass
+
 
 class _FakeMouse:
     def __init__(self, page):
@@ -33,6 +40,40 @@ class _FakeMouse:
     def click(self, x, y):
         self._page.calls.append(("mouse_click", x, y))
 
+    def move(self, x, y):
+        self._page.calls.append(("mouse_move", x, y))
+
+
+class _FakeKeyboard:
+    def __init__(self, page):
+        self._page = page
+
+    def press(self, key):
+        self._page.calls.append(("key_press", key))
+
+    def type(self, text):
+        self._page.calls.append(("key_type", text))
+
+
+class _FakeCDP:
+    def __init__(self):
+        self.sent = []
+        self.handlers = {}
+
+    def on(self, event, handler):
+        self.handlers[event] = handler
+
+    def send(self, method, params=None):
+        self.sent.append((method, params or {}))
+
+
+class _FakeContext:
+    def __init__(self, cdp):
+        self.cdp = cdp
+
+    def new_cdp_session(self, page):
+        return self.cdp
+
 
 class _FakePage:
     def __init__(self):
@@ -40,6 +81,9 @@ class _FakePage:
         self.calls = []
         self.shot_path = None
         self.mouse = _FakeMouse(self)
+        self.keyboard = _FakeKeyboard(self)
+        self.cdp = _FakeCDP()
+        self.context = _FakeContext(self.cdp)
 
     def title(self):
         return "Example Domain"
@@ -60,6 +104,11 @@ class _FakePage:
 
     def evaluate(self, expression):
         self.calls.append(("evaluate", expression))
+        if "querySelectorAll" in expression:
+            return [{"tag": "button", "role": "", "name": "GO",
+                     "path": "button"},
+                    {"tag": "a", "role": "link", "name": "Home",
+                     "path": "a"}]
         return 42
 
     def screenshot(self, path=None):
@@ -166,6 +215,50 @@ class BrowserTest(unittest.TestCase):
         with self.assertRaises(BrowserError):
             self.browser.click_at("left", 10)
 
+    def test_remote_input_methods(self):
+        self.browser.navigate("https://example.com")
+        out = self.browser.mouse_move(10, 20)
+        self.assertTrue(out["ok"])
+        self.assertIn(("mouse_move", 10, 20), self.page.calls)
+        out = self.browser.key_press("Enter")
+        self.assertTrue(out["ok"])
+        self.assertIn(("key_press", "Enter"), self.page.calls)
+        out = self.browser.type_text("hi")
+        self.assertTrue(out["ok"])
+        self.assertIn(("key_type", "hi"), self.page.calls)
+        with self.assertRaises(BrowserError):
+            self.browser.mouse_move(9999, 10)
+
+    def test_snapshot_refs_and_click_ref(self):
+        self.browser.navigate("https://example.com")
+        out = self.browser.snapshot_refs()
+        self.assertEqual(out["count"], 2)
+        self.assertEqual(out["elements"][0]["ref"], "e0")
+        self.assertEqual(out["elements"][0]["name"], "GO")
+        clicked = self.browser.click_ref("e0")
+        self.assertTrue(clicked["ok"])
+        self.assertEqual(clicked["ref"], "e0")
+        self.assertIn(("locator", "button"), self.page.calls)
+        with self.assertRaises(BrowserError):
+            self.browser.click_ref("e99")
+
+    def test_screencast_attach_and_pump(self):
+        from playwright_remote import SimpleQueue
+        sink = SimpleQueue()
+        self.browser.set_frame_sink(sink)
+        self.browser.navigate("https://example.com")
+        self.assertIn(("Page.startScreencast",
+                       {"format": "jpeg", "quality": 60,
+                        "maxWidth": 1280, "maxHeight": 800,
+                        "everyNthFrame": 2}),
+                      [(m, p) for m, p in self.page.cdp.sent])
+        handler = self.page.cdp.handlers["Page.screencastFrame"]
+        handler({"sessionId": "s1", "data": "FRAMEDATA"})
+        frame = self.browser.pump_screencast()
+        self.assertEqual(frame, "FRAMEDATA")
+        self.assertIn(("Page.screencastFrameAck", {"sessionId": "s1"}),
+                      [(m, p) for m, p in self.page.cdp.sent])
+
     def test_live_shot_writes_fixed_file_and_status(self):
         self.browser.navigate("https://example.com")
         out = self.browser.live_shot()
@@ -192,6 +285,22 @@ class FakeMCPBrowser:
                 "path": "/w/browser-live.png", "bytes": 456,
                 "url": "https://x/", "title": "T", "timestamp": 1}
 
+    def mouse_move(self, x, y):
+        return {"ok": True, "x": x, "y": y}
+
+    def key_press(self, key):
+        return {"ok": True, "key": key}
+
+    def type_text(self, text):
+        return {"ok": True}
+
+    def snapshot_refs(self):
+        return {"elements": [{"ref": "e0", "tag": "button",
+                              "role": "", "name": "GO"}], "count": 1}
+
+    def click_ref(self, ref):
+        return {"ok": True, "ref": ref}
+
     def snapshot(self):
         return {"url": "https://x/", "title": "T", "text": "hi",
                 "truncated": False}
@@ -223,6 +332,32 @@ class MCPTest(unittest.TestCase):
         self.assertIn("https://example.com", text)
         self.assertFalse(resp["result"]["isError"])
 
+    def test_holder_user_blocks_agent_tools(self):
+        import playwright_mcp
+        fake = FakeMCPBrowser()
+        remote = playwright_mcp._get_remote(fake)
+        remote.set_holder("user")
+        try:
+            resp = handle_request(
+                {"jsonrpc": "2.0", "id": 3, "method": "tools/call",
+                 "params": {"name": "browser_navigate",
+                            "arguments": {"url": "https://example.com"}}},
+                browser=fake)
+            self.assertTrue(resp["result"]["isError"])
+            self.assertIn("holds browser control",
+                          resp["result"]["content"][0]["text"])
+        finally:
+            remote.set_holder("agent")
+
+    def test_new_tools_listed(self):
+        listed = handle_request({"jsonrpc": "2.0", "id": 4,
+                                 "method": "tools/list"})
+        names = [t["name"] for t in listed["result"]["tools"]]
+        for name in ("browser_snapshot_refs", "browser_click_ref",
+                     "browser_mouse_move", "browser_key_press",
+                     "browser_type_text"):
+            self.assertIn(name, names)
+
 
 if __name__ == "__main__":
     unittest.main()