writing-commit-messages

name	writing-commit-messages
description	Writes Git commit messages. Activates when the user asks to write a commit message, draft a commit message, or similar.

Writing Commit Messages

Write commit messages that follow commit style guidelines for the project.

Format

<subsystem>: <summary>

<reference issues/PRs/etc.>

<long form description>

Rules

Subject line

• Subsystem prefix: Use a short, lowercase identifier for the area of code changed (e.g., terminal, vt, lib, config, font). Determine this from the file paths in the diff. If changes span the macOS app, use macos. For GTK, use gtk. For build system, use build. Use nested subsystems with / when helpful and exclusive (e.g., terminal/osc).
• Summary: Lowercase start (not capitalized), imperative mood, no trailing period. Keep it concise—ideally under 60 characters total for the whole subject line.

References

• If the change relates to a GitHub issue, PR, or discussion, list the relevant numbers on their own lines after the subject, separated by a blank line. E.g. #1234
• If there are no references, omit this section entirely (no blank line).

Long form description

• Describe what changed, what the previous behavior was, and how the new behavior works at a high level.
• Use plain prose, not bullet points. Wrap lines at ~72 characters.
• Focus on the why and how rather than restating the diff.
• Keep the tone direct and technical without filler phrases.
• Don't exceed a handful of paragraphs; less is more.

Workflow

• If .jj is present, use jj instead of git for all commands.
• Run a diff to see what changes are present since the last commit.
• Identify the subsystem from the changed file paths.
• Identify any referenced issues/PRs from the diff context or branch name.
• Draft the commit message following the format above.
• Apply the commit
• Don't push the commit; leave that to the user.