fix stop button disabled during connection

apps/studio/tools/ui_check.py

@@ -15,6 +15,8 @@ from __future__ import annotations
 
 import os
 import sys
+import threading
+import time
 from pathlib import Path
 
 APP_ROOT = Path(__file__).resolve().parents[1]
@@ -45,6 +47,55 @@ def section(name: str) -> None:
     print(f"\n== {name} ==")
 
 
+class _StuckWorker:
+    """A worker whose device open never returns.
+
+    Mirrors the real worker's non-blocking ``stop()`` contract so the window can
+    be exercised against the failure mode the Stop button exists to survive.
+    """
+
+    def __init__(self) -> None:
+        self._thread: threading.Thread | None = None
+        self._end_reason: str | None = None
+        self.thread_still_owned = False
+        self.stop_blocked_for = 0.0
+
+    def start(self, _source, *, config_ref=None) -> None:
+        self._thread = threading.Thread(target=self._hang, daemon=True)
+        self._thread.start()
+
+    def _hang(self) -> None:
+        time.sleep(600.0)
+
+    @property
+    def is_running(self) -> bool:
+        return self._thread is not None and self._thread.is_alive()
+
+    @property
+    def phase(self) -> str:
+        return "connecting"
+
+    def latest(self):
+        return None
+
+    def consume_end_reason(self):
+        reason, self._end_reason = self._end_reason, None
+        return reason
+
+    def reset(self) -> None:
+        return None
+
+    def stop(self, *, wait: bool = False) -> None:
+        self._end_reason = self._end_reason or "stopped"
+        started = time.perf_counter()
+        if wait and self._thread is not None and self._thread.is_alive():
+            self._thread.join(timeout=5.0)
+        if self._thread is None or not self._thread.is_alive():
+            self._thread = None
+        self.thread_still_owned = self._thread is not None
+        self.stop_blocked_for = time.perf_counter() - started
+
+
 # --------------------------------------------------------------------------
 # Palette rules
 #
@@ -440,6 +491,74 @@ def main() -> int:
     window.close()
     app.processEvents()
 
+    section("stopping a hung connect")
+    stuck = _StuckWorker()
+    window = StudioMainWindow(
+        prefs={
+            "language": "zh_CN",
+            "theme": "dark",
+            "sensor_type": "box",
+            "source_mode": "camera",
+        }
+    )
+    window.resize(1440, 880)
+    window.show()
+    window._ensure_workers = lambda: None
+    window._box_worker = stuck
+    window._finger_worker = stuck
+    app.processEvents()
+
+    check(not window.act_stop.isEnabled(), "Stop shortcut is live before a session")
+    window.toolbar.btn_run.setChecked(True)
+    app.processEvents()
+
+    check(window._session_phase == "connecting", "run did not enter the connecting phase")
+    check(
+        window.toolbar.btn_run.isEnabled(),
+        "Stop is disabled while connecting — a hung connect could not be cancelled",
+    )
+    check(window.toolbar.btn_run.isChecked(), "run button did not latch into the stop state")
+    check(
+        window.toolbar.btn_run.text() == t("toolbar.cancel_label"),
+        f"connecting label is not the cancel label: {window.toolbar.btn_run.text()!r}",
+    )
+    check(
+        window.toolbar.btn_run.toolTip() == t("toolbar.cancel_tip"),
+        "connecting tooltip does not explain how to cancel",
+    )
+    check(window.act_stop.isEnabled(), "Stop shortcut is disabled while connecting")
+
+    started = time.perf_counter()
+    window.toolbar.btn_run.setChecked(False)
+    elapsed = time.perf_counter() - started
+    check(elapsed < 0.5, f"Stop blocked the GUI for {elapsed:.2f}s on a hung connect")
+    check(not window._running, "session stayed active after Stop")
+    check(window._session_phase == "idle", "phase did not return to idle after Stop")
+    check(
+        stuck.thread_still_owned,
+        "Stop abandoned the still-running worker thread",
+    )
+
+    # The slow-connect hint must point at the escape hatch.
+    window.toolbar.btn_run.setChecked(True)
+    app.processEvents()
+    window._connect_started_at = time.perf_counter() - 3600.0
+    window._on_run_tick()
+    check(
+        window.statusBar().currentMessage() == t("status.connect_slow"),
+        f"no slow-connect hint: {window.statusBar().currentMessage()!r}",
+    )
+
+    escaped = time.perf_counter()
+    window._on_stop_shortcut()
+    check(
+        time.perf_counter() - escaped < 0.5,
+        "Esc did not cancel the hung connect immediately",
+    )
+    check(not window._running, "Esc left the session running")
+    window.close()
+    app.processEvents()
+
     print(f"\nscenes: {scene_count}   checks: {CHECKS}   failures: {len(FAILURES)}")
     for failure in FAILURES:
         print(f"  FAIL: {failure}")