Gallery tiles are 56px but were downloading the full ~280kB original. Previews
are now rendered with sharp and stored beside the originals in the same MinIO
bucket under a thumbs/ prefix, so nothing about credentials, lifecycle or backup
changes. Measured on live assets: 216-294kB originals become 13-19kB at 256px,
about 16x smaller; 640px is about 4x.
Both paths, as asked:
- Rendered when a job completes, so the first viewer never waits for a resize.
A preview failure never unmakes a finished job.
- Rendered on demand for anything that has none — the existing 26 images work
immediately with no backfill required, and the result is stored for next time.
Boundaries that matter more than the speed:
- Only 256 and 640 are honoured. An open width parameter would let a caller
drive arbitrary resizes.
- Permission is checked against the ORIGINAL before a preview is served, so a
preview can never widen who can see an image.
- Previews carry their own SHA-256 and owner headers, because the client
verifies both on every asset; sending the original's checksum would be
rejected as tampering, which is that check working correctly.
- Still private, no-store. The client asset pattern was widened to exactly
?w=256 and ?w=640 and nothing else.
Client-side downscaling stays as the fallback when a preview cannot be produced.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018e1PLqrKgAM9jQhFKRnbLd
