Only proxies of raws that take the per-file camera look (Photo::relative_wb) go stale: JPEG/PNG/DNG proxies are never rebuilt for the look. The opening scan runs once per LOOK_VERSION (a look-version marker in the smart previews folder), not at every library open; Build Smart Previews still refreshes stale proxies. Each proxy is checked and written under one lock, so the background refresh and library.smartPreviews never write the same file at once. LOOK_VERSION 2: main's DRO / ILCE-7CR camera-look changes (#528, #583, #568, #616).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>