generatePreviewImage rewrites the output extension to match the encoding
it chose, .jpg or .webp for alpha and multi-frame sources. The tier
lookup in ensurePreviewImageAtWidth and the cleanup list in
previewTierKeys kept the SOURCE extension instead, so for anything but a
lowercase .jpg source the stat never matched: every tier request for a
.png, .JPG, .jpeg, .heic or RAW photo re-ran Sharp, and cleanup never
found the files it left behind, which accumulated for the life of the
install.
Both now derive every key the tier can live under: the .jpg and .webp
candidates, plus the source-extension key last so tiers written before
the rewrite are still found by lookup and by cleanup.
Follow-up to issue 1020, where the mismatch was identified during review.
Co-authored-by: Paul Nothaft <paul@MacStudio-von-Paul.local>
Paul Nothaft