- attach.VariantKey: a thumbnail's copy in another format next to it - attach/webp (separate package, so only binaries that import it link the encoder): Encode at quality 80 and Variant, which writes the WebP copy of a thumbnail once and leaves no file on a failed encode - github.com/gen2brain/webp v0.6.4, decided in .planning/notes/2026-10-28-webp-gen2brain.md - lagoon README and docs/database/attachments.md