Commit messages

A commit message is read once in review and then repeatedly, years later, by someone asking "why is this line here?" The diff already says what changed. The message exists to say why.

git log --oneline should read as a plausible account of how the code got this way. If it reads "fix", "wip", "fix again", the history has no value and neither does git blame.

1. Commit one thing

Before writing anything, check what is staged. If the change contains a bug fix and a rename and a dependency bump, it cannot be described in one sentence, because it is three commits.

Split when the parts could be reverted independently, when one is mechanical and one needs thought, or when you find yourself writing "and".

git add -p          # stage selectively