fix: correct task scheduling and simplify agent internals

Fix queue cancellation, concurrency limits and worker status updates.

Use direct Explorer imports, split the Diagnoser loop into helpers and remove unused tool registration and prompt-builder code.

Correct model caching, endpoint selection and retry handling.

tests/unit/runtime/test_awake_service.py

@@ -29,7 +29,10 @@ def test_usb_policy_is_primary_when_android_reports_it_active(mock_run, lease_ty
     lease_type.assert_called_once_with("device-123")
     lease_type.return_value.cleanup_unowned_references.assert_called_once_with()
     commands = [call.args[0] for call in mock_run.call_args_list]
-    assert ["shell", "svc", "power", "stayon", "usb"] in [command[3:] for command in commands]
+    # Commands are endpoint-qualified (adb -H host -P port -s serial ...);
+    # assert on the payload after the serial rather than a fixed prefix width.
+    payloads = [command[command.index("-s") + 2 :] for command in commands if "-s" in command]
+    assert ["shell", "svc", "power", "stayon", "usb"] in payloads
     assert not any("SCREEN_BRIGHT_WAKE_LOCK" in command for command in commands)
     assert not any("KEYCODE_UNKNOWN" in command for command in commands)