streams when one viewer closes
1) Offline tiles now show OFF (not LIVE)
CameraWall.modeByPrinter assigned 'live' to any visible printer
without considering status.connected, so a disconnected X1C wasted
a live-budget slot AND rendered the red LIVE chip on top of the
WifiOff placeholder. Disconnected printers now map to 'paused' and
don't decrement liveBudget — the existing WifiOff + Off chip
rendering takes over.
2) /camera/stop no longer kills other viewers' streams
The cam-wall tile, EmbeddedCameraViewer, and the /camera/:id popup
all subscribe to the same fan-out broadcaster for a printer.
/camera/stop used to unconditionally shutdown_broadcaster() + kill
every ffmpeg process for the printer, so closing the embedded viewer
while the cam-wall tile of the same printer was live force-killed
the source the tile was pulling from — the tile's <img> errored.
New get_subscriber_count(key) accessor in camera_fanout.py exposes
the broadcaster's subscriber list length. /camera/stop now reads
that first; when >= 1 subscriber is still attached, return
{stopped: 0, skipped: true} and leave the broadcaster + ffmpeg
processes alone. The leaving viewer's HTTP teardown still runs the
natural iter_subscriber.finally -> unsubscribe path, so its slot is
released; the broadcaster keeps serving the other viewers. Single-
viewer close still hits the immediate force-teardown (count is 0).
Most Bambu Lab printers only allow one concurrent camera connection, but
GET /printers/{id}/camera/stream opened a fresh upstream per viewer.
Two browser tabs → second viewer fails or kicks the first off.
New MjpegBroadcaster (services/camera_fanout.py) owns one upstream per
printer and fans MJPEG chunks out to N subscribers. 5 s grace window
absorbs tab refreshes without reconnecting. Bounded subscriber queues
drop frames for slow viewers rather than blocking the broadcaster.
Audit-pass fixes:
- _stream_start_times set with setdefault() so stream_uptime reflects
the shared upstream's age, not the most-recent viewer's
- subscribe() retried once on RuntimeError to close a tiny grace race
- unsubscribe() returns post-removal count atomically so the detach log
no longer races with concurrent leavers
Permission gates unchanged; broadcaster has no FastAPI surface.
Tests: 13 broadcaster unit tests + 2 integration tests on /camera/stop.
External-camera path untouched.
maziggy