feat(planner): add execution context to prompts

apps/device-host-agent/host_agent/execution.py

@@ -50,6 +50,9 @@ def create_execution_factories(
             timeline=timeline,
             planner=_host_agent_planner(resolved_host_agent_config),
             planner_config=_host_agent_planner_config(),
+            device_platform_provider=lambda device_id: _device_platform(
+                manager, device_id
+            ),
         )
 
     def create_workflow_runner() -> WorkflowRunner:
@@ -103,3 +106,15 @@ def _host_agent_planner(
         client=CloudProxyToolCallingClient(resolved_config),
         config=planner_config,
     )
+
+
+def _device_platform(manager: DeviceManager, device_id: str) -> str | None:
+    for device in manager.list_devices():
+        if device.id != device_id:
+            continue
+        if device.driver_type == "wda":
+            return "ios"
+        if device.driver_type == "uiautomator2":
+            return "android"
+        return None
+    return None