Improve local agent chat and device health detection

apps/device-host-agent/tests/test_config.py

@@ -34,6 +34,8 @@ def test_load_host_agent_config_supports_local_mode() -> None:
     assert config.control_plane_url == ""
     assert config.enrollment_managed is False
     assert config.ai_planner_transport == "direct"
+    assert config.dependency_supervisor_enabled is True
+    assert config.appium_supervised is True
 
 
 def test_load_host_agent_config_parses_poll_and_retry_values() -> None:

apps/device-host-agent/tests/test_heartbeat.py

@@ -17,6 +17,9 @@ class ConnectableDriver:
     def connect(self) -> None:
         return None
 
+    def screenshot(self) -> bytes:
+        return b"ok"
+
 
 def _config() -> HostAgentConfig:
     return HostAgentConfig(
@@ -89,6 +92,33 @@ def test_heartbeat_synchronizer_runs_at_configured_interval_until_stopped() -> N
     assert manager.status("device-a") == "busy"
 
 
+def test_offline_device_is_retried_on_next_heartbeat_cycle() -> None:
+    class FlakyDriver(ConnectableDriver):
+        def __init__(self, fail: bool) -> None:
+            self.fail = fail
+
+        def screenshot(self) -> bytes:
+            if self.fail:
+                raise RuntimeError("WDA disconnected")
+            return b"ok"
+
+    instances: list[FlakyDriver] = []
+
+    def factory() -> FlakyDriver:
+        driver = FlakyDriver(not instances)
+        instances.append(driver)
+        return driver
+
+    manager = DeviceManager()
+    manager.register_device("device-a", factory)  # type: ignore[arg-type]
+    manager.connect("device-a")
+    sync = HeartbeatSynchronizer(manager, object(), _config())  # type: ignore[arg-type]
+    sync.probe_connected_devices()
+    assert manager.status("device-a") == "offline"
+    sync.connect_devices()
+    assert manager.status("device-a") == "busy"
+
+
 def test_sync_once_notifies_status_tracker_and_on_sync_with_device_count() -> None:
     manager = DeviceManager()
     manager.register_device(