One Thing Per Commit

Bad commit:

commit abc1234
  - Add dark mode feature
  - Fix auth bug
  - Refactor database layer
  - Update docs

Six months later, a feature breaks. You git bisect. The commit that introduced it also has four other changes. Which one broke it? Unknown.

Good commits:

commit abc1234
  Add dark mode CSS variables

commit abc1235
  Wire dark mode toggle to localStorage

commit abc1236
  Fix auth token expiry bug

commit abc1237
  Refactor database connection pool

Each commit is atomic — it does one thing. You can revert it, cherry-pick it, understand it.

Commit messages that work:

✔ Add dark mode toggle to settings
✔ Fix race condition in token refresh
✔ Extract cache layer to separate module

✗ wip
✗ fix stuff
✗ checkpoint

Discipline compounds. One thing per commit. Bisect catches bugs in seconds. The blame is clear. New developers can read the history.

Commit early, commit often. One thing at a time.