Restore the per-batch visibility lost in the cart migration: applyDelta now logs 'delta applied epoch=N (+U/-D, overlay=X)', and the snapshot swap line includes 'snapshot' so it's findable. Deltas were applying silently, which read as 'nothing happened' on a bulk catalog update (only the debounced snapshot swap was logged). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>