perf(fast-browser): bound readiness polling and verify asynchronous tab close

extensions/fast-browser/browser_worker.py

@@ -824,7 +824,18 @@ class RealBrowserBackend:
         return self._helpers.cdp("Page.reload")
 
     def wait_ready(self, timeout: float = NAVIGATION_TIMEOUT_SECONDS) -> bool:
-        return bool(self._helpers.wait_for_load(timeout=timeout))
+        # Keep the harness' exact readyState query, but avoid its coarse 300ms
+        # sleep. This is only a readiness read; it never dispatches navigation.
+        if timeout <= 0:
+            return False
+        deadline = time.monotonic() + timeout
+        while True:
+            if self._helpers.js("document.readyState") == "complete":
+                return True
+            remaining = deadline - time.monotonic()
+            if remaining <= 0:
+                return False
+            time.sleep(min(0.025, remaining))
 
     def visible_text_content(self) -> str:
         # This is a fixed, worker-owned read operation.  No caller expression,
@@ -1708,13 +1719,20 @@ class BrowserRuntimeWorker(BrowserWorker):
             raise self._fail("closeTab", "aborted", "close", "tab close was cancelled",
                              mutation_state="unknown" if self._mutation_dispatched else "not_attempted")
         # Do not assume a close acknowledgement means the target disappeared;
-        # verify the current target inventory before reporting a verified close.
-        try:
-            self._refresh_tabs()
-        except BrowserOperationError:
-            raise self._fail("closeTab", "worker_failure", "verify", "tab close could not be verified", mutation_state="unknown")
-        if tab.target_id in self._target_to_tab:
-            raise self._fail("closeTab", "worker_failure", "verify", "tab close could not be verified", mutation_state="unknown")
+        # verify inventories until the target is gone or the existing action
+        # budget expires. The close mutation itself is dispatched exactly once.
+        deadline = time.monotonic() + ACTION_TIMEOUT_SECONDS
+        while True:
+            try:
+                self._refresh_tabs()
+            except BrowserOperationError:
+                raise self._fail("closeTab", "worker_failure", "verify", "tab close could not be verified", mutation_state="unknown")
+            if tab.target_id not in self._target_to_tab:
+                break
+            remaining = deadline - time.monotonic()
+            if remaining <= 0:
+                raise self._fail("closeTab", "worker_failure", "verify", "tab close could not be verified", mutation_state="unknown")
+            time.sleep(min(0.025, remaining))
         self._target_to_tab.pop(tab.target_id, None)
         self._tabs.pop(tab.tab_id, None)
         if self._selected_tab_id == tab.tab_id: