fix: bound task failures and release stalled workers

tests/unit/test_drivers.py

@@ -14,7 +14,9 @@
 
 """Unit tests for Unified Base Device Driver and implementations."""
 
+import asyncio
 import base64
+import threading
 from io import BytesIO
 from types import SimpleNamespace
 from unittest.mock import AsyncMock, MagicMock
@@ -36,6 +38,48 @@ _ONE_PIXEL_PNG = base64.b64encode(
 ).decode("ascii")
 
 
+def _valid_png():
+    buffer = BytesIO()
+    Image.new("RGB", (64, 64), "white").save(buffer, format="PNG")
+    return base64.b64encode(buffer.getvalue()).decode("ascii")
+
+
+_VALID_PNG = _valid_png()
+
+
+@pytest.mark.asyncio
+async def test_android_driver_rejects_placeholder_without_returning_stale_screen():
+    client = MagicMock()
+    client.get_screen_data.return_value = SimpleNamespace(base64=_ONE_PIXEL_PNG)
+    driver = AndroidAdbDriver("test-device", MagicMock(), ui_adb_client=client)
+    with pytest.raises(RuntimeError, match="占位图"):
+        await driver.get_screen_data(skip_settling=True)
+
+
+@pytest.mark.asyncio
+async def test_screen_capture_timeout_does_not_start_overlapping_sdk_calls(monkeypatch):
+    released = threading.Event()
+    client = MagicMock()
+
+    def blocked_capture():
+        released.wait(2)
+        return SimpleNamespace(base64=_VALID_PNG, width=64, height=64, elements=[])
+
+    client.get_screen_data.side_effect = blocked_capture
+    driver = AndroidAdbDriver("test-device", MagicMock(), ui_adb_client=client)
+    monkeypatch.setattr(
+        "artemis.drivers.android.adb_driver.settings.ARTEMIS_OBSERVATION_TIMEOUT_SECONDS", 0.02
+    )
+    try:
+        for _ in range(3):
+            with pytest.raises(TimeoutError, match="观测超时"):
+                await driver.get_screen_data(skip_settling=True)
+        assert client.get_screen_data.call_count == 1
+    finally:
+        released.set()
+        await asyncio.wait_for(driver._screen_capture_task, 2)
+
+
 def test_screenshot_limit_keeps_small_and_invalid_images_unchanged():
     small_image = base64.b64decode(_ONE_PIXEL_PNG)
     assert limit_screenshot_long_edge(small_image, 2048) is small_image
@@ -100,16 +144,16 @@ async def test_android_driver_with_mock_adb():
 
     # Test tap
     await driver.tap(540, 1200)
-    mock_adb_device.shell.assert_called_with("input tap 540 1200")
+    mock_adb_device.shell.assert_called_with("input tap 540 1200", timeout=10.0)
 
     # Test multi-tap
     await driver.tap(540, 1200, times=3, delay_ms=100)
     expected_multi = "input tap 540 1200 && sleep 0.100 && input tap 540 1200 && sleep 0.100 && input tap 540 1200"
-    mock_adb_device.shell.assert_called_with(expected_multi)
+    mock_adb_device.shell.assert_called_with(expected_multi, timeout=10.0)
 
     # Test press key
     await driver.press_key(KeyCode.BACK)
-    mock_adb_device.shell.assert_called_with("input keyevent 4")
+    mock_adb_device.shell.assert_called_with("input keyevent 4", timeout=10.0)
 
 
 @pytest.mark.asyncio
@@ -132,7 +176,7 @@ async def test_android_driver_preserves_elements_from_combined_screen_data():
         },
     ]
     mock_ui_client.get_screen_data.return_value = SimpleNamespace(
-        base64=_ONE_PIXEL_PNG,
+        base64=_VALID_PNG,
         hierarchy_xml="<hierarchy />",
         elements=expected_elements,
         width=1080,
@@ -188,7 +232,7 @@ async def test_android_driver_parses_xml_hierarchy_fallback():
     mock_adb_client = MagicMock()
     mock_ui_client = MagicMock()
     mock_ui_client.get_screen_data.return_value = SimpleNamespace(
-        base64=_ONE_PIXEL_PNG,
+        base64=_VALID_PNG,
         width=1080,
         height=2400,
     )
@@ -216,7 +260,7 @@ async def test_find_element_prefers_fresh_bounds_over_stale_center():
     driver.get_screen_data = AsyncMock(
         return_value=ScreenData(
             screenshot_bytes=base64.b64decode(_ONE_PIXEL_PNG),
-            screenshot_base64=_ONE_PIXEL_PNG,
+            screenshot_base64=_VALID_PNG,
             ui_elements=[
                 {
                     "resource_id": "app:id/digit_4",