The U1 exposes no /server/webcams/list entry;
its camera only captures after an explicit
camera.start_monitor RPC, which the Moonraker
websocket executes unauthenticated but only
answers over MQTT - so the call is fire and
forget.
Start the camera when the camera view is
shown and renew every 300 s: the printer
retires the capture task at ~362 s and
stop_monitor is accepted but ineffective,
so teardown is simply to stop renewing.
Frames land in monitor.jpg as still JPEGs
(~2 fps at interval 0), so the webview loads
a local HTML wrapper that repolls with a
cache buster.
Lam Wei Lun