From a parallel session. thumbs.generate accepts a file or an indexed
folder with missing, stale, and force modes, runs in resumable batches,
and versions video tiles against host FFmpeg availability so a tile
regenerated with better tooling replaces its predecessor in place. File
and folder context menus and the new sd thumbs CLI domain call the same
operation. paths.context now reports whether the exact path has a
committed source record, and the path bar surfaces it with a refresh
affordance. Coverage and resume semantics are documented in
docs/core/thumbnail-generation.mdx.