Stacked diffs

A long change split into a chain of pull requests, each built on the one before it, so each can be reviewed alone and you don't have to wait for the first to merge before writing the next.

An agent works faster than any reviewer, so it will always want to carry on before the last piece has been read. A stack lets it, while keeping each piece small. The cost is that a fix low down means updating everything above, and that is the kind of chore you can hand to an agent.