The file half of the remedy for what #300 could only stop. Fixing the EXIF strip means new uploads arrive the way the sender saw them; it cannot repair what is already stored, because the tag that said which way up the pixels went is gone. Those photos need a person to look at each one and turn it.
Rewrites the pixels rather than recording an angle, because an angle obliges every consumer to honour it — the storefront, both admin screens, the drafting worker's photo reader, and the rembg sidecar — and any one that forgets shows the photo sideways. The sidecar is not ours to teach.
Left is anticlockwise and right is clockwise, which is rotate(-90) and rotate(90); sharp reads a positive angle as clockwise. The direction test asserts a pixel rather than a dimension, because dimensions swap whichever way the turn goes — a reversed sign would pass every size assertion and ship a control that does the opposite of its label.
The animated WebP case is the one that could destroy someone's file quietly. Reading such a file without the animated flag succeeds and hands back the first frame alone, so a rotation that omitted it would write a still back over the animation and report success. Passing the same flag reencodeInPlace passes makes sharp refuse instead — multi-page images turn only by 180° — which is the honest answer and leaves the file untouched.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
bermudalambandClaude Opus 5
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