feat: add on-demand device screenshots

tests/test_device_manager.py

@@ -46,3 +46,29 @@ def test_probe_marks_connected_device_offline_when_driver_is_unreachable() -> No
 
     assert manager.probe("iphone-1") is False
     assert manager.status("iphone-1") == "offline"
+
+
+def test_probe_uses_health_check_without_capturing_screen() -> None:
+    class HealthCheckedDriver:
+        def __init__(self) -> None:
+            self.health_checks = 0
+            self.screenshots = 0
+
+        def connect(self) -> None:
+            return None
+
+        def screenshot(self) -> bytes:
+            self.screenshots += 1
+            return b"screen"
+
+        def health_check(self) -> None:
+            self.health_checks += 1
+
+    driver = HealthCheckedDriver()
+    manager = DeviceManager()
+    manager.register_device("iphone-1", lambda: driver)  # type: ignore[arg-type]
+    manager.connect("iphone-1")
+
+    assert manager.probe("iphone-1") is True
+    assert driver.health_checks == 1
+    assert driver.screenshots == 0