POST /prompt_manager/jobs/image-tags starts one record-changing
"image-tags" job over 1..500 listed images (202, or the same 409 busy
envelope as /jobs/scan). Add tags hashes each current file and unions a
fixed set into that byte record; Auto-tag captures each still image, asks
one legacy engine for its top N suggestions on the capture (count from
the options or autotag.defaults.suggestion_limit), re-hashes the file and
unions only onto the same bytes. Outcomes are grouped as tagged,
unchanged, skipped (video, too large, file changed, file not found, not a
still image) and errors; cancel stops at a file boundary.
Auto-tag holds the shared model gate for the whole job (409 model-busy at
start when it is held), loads the model once and never downloads one: an
unavailable model fails the job before the first file. The registry gains
blocker() so a start answers busy before taking the gate.