fix(daemon): bound CDP request waits

src/browser_harness/daemon.py

@@ -33,6 +33,7 @@ def _load_env_file(p):
 LOG = str(ipc.log_path(NAME))
 PID = str(ipc.pid_path(NAME))
 BUF = 500
+CDP_CALL_TIMEOUT = 4.5
 PROFILES = [
     Path.home() / "Library/Application Support/Google/Chrome",
     Path.home() / "Library/Application Support/Google/Chrome Canary",
@@ -229,6 +230,17 @@ async def enable_one(d):
                 log(f"enable {d} on {session_id}: {e}")
         await asyncio.gather(*(enable_one(d) for d in ("Page", "DOM", "Runtime", "Network")))
 
+    async def send_cdp(self, method, params=None, session_id=None):
+        if self.cdp is None:
+            raise RuntimeError("CDP client not started")
+        try:
+            return await asyncio.wait_for(
+                self.cdp.send_raw(method, params, session_id=session_id),
+                timeout=CDP_CALL_TIMEOUT,
+            )
+        except asyncio.TimeoutError:
+            raise TimeoutError(f"{method} timed out after {CDP_CALL_TIMEOUT:g}s") from None
+
     async def start(self):
         self.stop = asyncio.Event()
         url = get_ws_url()
@@ -346,13 +358,13 @@ async def disable_old():
         # For everything else, explicit session in req wins; else default.
         sid = None if method.startswith("Target.") else (req.get("session_id") or self.session)
         try:
-            return {"result": await self.cdp.send_raw(method, params, session_id=sid)}
+            return {"result": await self.send_cdp(method, params, session_id=sid)}
         except Exception as e:
             msg = str(e)
             if "Session with given id not found" in msg and sid == self.session and sid:
                 log(f"stale session {sid}, re-attaching")
                 if await self.attach_first_page():
-                    return {"result": await self.cdp.send_raw(method, params, session_id=self.session)}
+                    return {"result": await self.send_cdp(method, params, session_id=self.session)}
             return {"error": msg}
 
 

tests/unit/test_daemon.py

@@ -293,3 +293,36 @@ def test_current_tab_meta_returns_not_attached_when_no_target_id():
     assert result == {"error": "not_attached"}
     # No CDP call should have been issued.
     assert d.cdp.calls == []
+
+
+def test_regular_cdp_calls_timeout_before_client_socket_deadline(monkeypatch):
+    """If Chrome/CDP stops answering, daemon.handle() must return a useful
+    error before the helpers.py IPC client hits its 5s socket timeout.
+
+    Otherwise the helper sees only a client-side timeout at _ipc.request(),
+    and the daemon can later log ``conn: Connection lost`` when it finally
+    tries to write to a socket the helper already closed.
+    """
+    class _HangingCDP:
+        def __init__(self):
+            self.calls = []
+
+        async def send_raw(self, method, params=None, session_id=None):
+            self.calls.append((method, params, session_id))
+            await asyncio.Event().wait()
+
+    d = daemon.Daemon()
+    d.cdp = _HangingCDP()
+    d.session = "session-current"
+    monkeypatch.setattr(daemon, "CDP_CALL_TIMEOUT", 0.01, raising=False)
+
+    async def run():
+        return await asyncio.wait_for(
+            d.handle({"method": "Page.navigate", "params": {"url": "https://example.com"}}),
+            timeout=0.5,
+        )
+
+    result = asyncio.run(run())
+
+    assert result == {"error": "Page.navigate timed out after 0.01s"}
+    assert d.cdp.calls == [("Page.navigate", {"url": "https://example.com"}, "session-current")]