Two tree check-ins were diffed by flattening both to full file lists, files-per-check-in per check-in: 34 minutes once on a pkgsrc mirror. The S-card runs are now walked side by side, skipping every sub-manifest whose hash did not move and resolving only where it did. Deletes are held to the end so a moved partition key cannot make a live file look deleted. Trees flatten on demand only for the root and flat/tree pairings; the derive feed never flattens. pkgsrc: 34.3 min -> 6.8 min. check-in: ea4abe48fd user: dmestas tags: trunk