writing-commit-messages

Source excerpt starting at line 1.

1---2name: writing-commit-messages3description: >-4  Writes Git commit messages. Activates when the user asks to write5  a commit message, draft a commit message, or similar.6---7 8# Writing Commit Messages9 10Write commit messages that follow commit style guidelines for the project.11 12## Format13 14```15<subsystem>: <summary>16 17<reference issues/PRs/etc.>18 19<long form description>20```21 22## Rules23 24### Subject line25 26- **Subsystem prefix**: Use a short, lowercase identifier for the27  area of code changed (e.g., `terminal`, `vt`, `lib`, `config`,28  `font`). Determine this from the file paths in the diff. If29  changes span the macOS app, use `macos`. For GTK, use `gtk`. For30  build system, use `build`. Use nested subsystems with `/` when31  helpful and exclusive (e.g., `terminal/osc`).32- **Summary**: Lowercase start (not capitalized), imperative mood,33  no trailing period. Keep it concise—ideally under 60 characters34  total for the whole subject line.35 36### References37 38- If the change relates to a GitHub issue, PR, or discussion, list39  the relevant numbers on their own lines after the subject, separated40  by a blank line. E.g. `#1234`41- If there are no references, omit this section entirely (no blank42  line).43 44### Long form description45 46- Describe **what changed**, **what the previous behavior was**,47  and **how the new behavior works** at a high level.48- Use plain prose, not bullet points. Wrap lines at ~72 characters.49- Focus on the _why_ and _how_ rather than restating the diff.50- Keep the tone direct and technical without filler phrases.51- Don't exceed a handful of paragraphs; less is more.52 53## Workflow54 55- If `.jj` is present, use `jj` instead of `git` for all commands.56- Run a diff to see what changes are present since the last commit.57- Identify the subsystem from the changed file paths.58- Identify any referenced issues/PRs from the diff context or59  branch name.60- Draft the commit message following the format above.61- Apply the commit62- Don't push the commit; leave that to the user.63