Reporter @Andlar94 ran the external-camera flow on an A1 dispatched via the
print queue and got no MP4 output even though the log said "Stitching layer
timelapse for printer 1" after each print. Support bundle confirmed the
external camera was working (Obico was polling the snapshot URL fine for
plate detection).
Root cause: start_session() only ran in the two new-archive paths in
on_print_start (fallback_archive at main.py:2510 and regular new-archive at
2600). The expected-archive branch at main.py:1981-2052 — where every
reprint and every queue/VP-dispatched print lands — updated the existing
archive row to status=printing but never started a timelapse session.
So _background_layer_timelapse ran at print complete, called tl_complete(),
found nothing in _active_sessions, returned None silently, and the wrapper
at main.py:3917 produced no log message for the no-session case. Every
print through the queue silently lost its timelapse — likely the reason
this hasn't been caught before (direct slice-and-send-to-printer prints
take the new-archive path and work fine).
Fix: mirror the same start_session() call in the expected-archive branch,
guarded by the same external_camera_enabled + external_camera_url check the
other two paths use.
Also reworded the snapshot URL help text across all 8 locales to make clear
that timelapse and plate detection each require their own per-printer
toggle — the URL is just the image source they pull from when active. The
previous wording read as if filling in the URL was sufficient.