To answer the usual question these days: the library, including the README which you can read, was written by hand, without LLM usage. I only played somewhat with Codex later on when creating derive macros and with some tests and examples, but that was all also highly manual.

This is awesome and I've needed it often. Could it hypothetically support filtered undo? For example in a collaborative app where not all edits are owned by the user.

good. it would be good to have 'size limit'(such as ring buffer). (or future feature - TTL,expiration)