f0f9753c42
Addresses @felixbrandt — fix(backend): "the two try blocks in generate() overlap — a save failure logs 'generation failed' even though the thumbnail is already in S3 as an orphan". generate() now orchestrates four stages, each in its own try+log: readSourceImage / encodeThumbnail / uploadToStorage / persistThumbnailMetadata persistThumbnailMetadata emits the distinct "orphaned in storage as <key>" log line so an operator can see database-side failures after the upload completed. The deterministic key ensures the next run overwrites cleanly, so the orphan is self-healing. Also extracts THUMBNAIL_KEY_PREFIX/SUFFIX constants with a comment explaining the deterministic-overwrite contract. Adds test: generate_returnsFailed_whenPersistThrows_butUploadSucceeded. Refs #307 Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>