An old thumbnail the finishing move cannot remove (held open on Windows)
is now an error row of the job with its path, and logged; a failed copy's
temp that cannot go is logged with its path. Every except that only
passes says why, and the thread runners say their caller re-raises.
POST /images/thumbnails/plan reviews a move (what is copied, removed and
left, free space, too-long Windows paths, sources no longer listed) and
hands out a token; POST /jobs/thumbnails {mode: move} runs it as a
thumbnails job: hold automatic previews, copy and check every preview on
the job pool, switch with one config commit that records the old copies,
then remove them. Per-file errors still switch; a folder-wide error, a
cancel before the switch or a crash leaves nothing changed (a journal is
undone at the next start); old copies that could not go are removed by a
finishing job at the next start. Leaving a folder removes the previews of
this install's sources that are no longer listed (Q320-8).
Recreate folder and Use this folder answer an unavailable folder; the
Thumbnail maintenance scope prune removes the thumbnails of removed
sources.
Marker keys are data, not paths: only a single <slug>-<hex> folder name
is ever joined onto the thumbnail folder; anything else is dropped and
logged. Every preview write and delete passes one ownership check (below a
key folder, lexically and resolved, no link, junction or reparse point on
the way); make_parent refuses anything else and writes nothing while the
folder lacks this install's marker (an unmounted mount point). Clear never
descends into a junction.
The configured location is in force before any request (unchecked folder
mode is unavailable), and a startup check that fails leaves it invalid,
never the sources. Older listings that run on the event loop no longer
touch the store in folder mode. A leftover under another case of
thumbnails/ on a case-insensitive disk is refused too.
thumbnails.location in config.json can now name one folder for every
source's previews: <folder>/<source key>/<rel>_thumb<ext>. A source key is
a readable slug plus a short hash of the source's identity, stored in the
folder's marker (.promptmanager-thumbnails.json) with the install that
made it. Serving, on-demand and capture writes, listings, clear, delete,
duplicates, the temp sweep and History covers all follow it; a leftover in
<source>/thumbnails is never served and other text under thumbnails/ is
refused.
A missing, unplugged or foreign folder is unavailable (a probe checks it
every 5 s within 2 s; a stalled or failing store call flips it at once):
originals are served, nothing is written anywhere, the folder is never
re-created, and generate, convert and clear answer 409
location-unavailable. A bad config value is unavailable too, never a
fall-back to the sources.
No UI yet: POST /settings refuses thumbnail_location (409
location-needs-move); GET /settings reports it with its path, the
thumbnail status without one. Sources inside or around the folder and a
library move into it are refused.