[{"device_id":"esp32s3-28848543a200","board":"m5stack-stopwatch","firmware":"0.5.1","online":true,"capabilities":["agent_target","approval","settings","speech_playback","voice_input"],"last_seen":"2026-10-04T13:17:27.960754+00:00","last_event":{"type":"heartbeat","uptime":783},"target":"agent:pi:01a0fcd2-7b96-77fb-a57a-40bbfb9fe5da","speech_mode":"OFF"}]