Within one subspace, a newer entry at a prefix removes every older entry with a longer path beneath it, so a folder is deleted in one write, leaving only the new entry.

It is how Willow delivers deletion without tombstones.

In one room, a path is a sequence of parts. Blog. Blog, ideas. Blog, drafts. Blog, game.

Write a newer entry at just blog.

Every older entry whose path starts with blog is gone. Ideas, drafts, game. All of them.

This is prefix pruning. A newer entry at a prefix overwrites everything longer beneath it.

That is how you delete a whole folder in one write. No tombstones for each file. One card at blog. Nothing else.

Check yourself. How many writes does it take to delete a folder with a thousand files?