Every cell on the People screen read "no preview" while the sweep was happily
reporting 893 faces found. Both were true. Faces were being detected and stored
correctly; there was simply nothing left to draw them from.
A face is stored normalised and drawn by cropping the proxy it was found on —
`identity::decode_proxy` reads `FACE_TIER` out of the thumbnail store. The
fetching sweep fetched a preview, detected on it, wrote the faces and dropped
the pixels. So every face it found pointed at a proxy that had never been
stored, and the grid had nothing to cut.
Worse, that state could not repair itself: the image has its `face_index` row,
so it is not outstanding work and no later pass would look at it again.
Two fixes, and the first is nearly free. The sweep now keeps the proxy — it has
already paid the round trip and the decode, and the crop needs those same pixels
the moment the user opens the person. Kept **only where a face was found**:
two thirds of a personal library is landscapes and documents (docs/faces.md
§7a), those will never be cropped, and skipping them keeps this well clear of
the whole-library cost `SWEEP_THUMB_SIZE` deliberately avoids. The downscale to
the large class happens after detection, which is the last use of the full
buffer.
Second, the sweep now picks up images that have faces with no proxy, whatever
put them in that state — this bug, or an ordinary cache eviction, which would
have produced exactly the same empty grid. Re-running detection repairs it and
loses nothing: `record_detections` replaces rather than appends and carries the
user's confirmations across the replacement. That makes the screen
self-healing rather than dependent on nobody ever evicting a thumbnail.
The proxy is stored *before* the detections. A kill between the two then leaves
a proxy with no faces — which the next pass simply re-indexes — rather than
faces with no proxy, which is the state that cannot recover.
Note for the library already part way through a sweep: the 986 images indexed
before this will be picked up by the repair route on the next run.
470 tests pass, including one that a face whose proxy is gone becomes work again.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
dtourolleandClaude Opus 5
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