[gmueckl]

You can do

> hg commit --amend

to change the topmost commit.

Marking commits as public is mostly a safeguard against accidentally altering history that others may already depend upon. This is just there to provide awareness of the giant footguns hiding when editing history after it has been shared (git contains the same footguns without safeguards). You can revert the status of a commit from public to draft and then change it. Just like in git, it's very dangerous to do so, but hg makes it very obvious. The command is

> hg phase --draft --force .