writing-commit-messages

name	writing-commit-messages
description	Writes commit messages and applies commits for bobrvm. Activates when the user asks to commit, 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: the subsystem, determined from the changed file paths: hypervisor, virtio, pci, gic, gpu, renderer, net, machine, snapshot, cli, agent, guest-tools, p9, runtime, apprt, console. Changes to the macOS app use macos, the Linux frontends linux or gtk, packaging nix or brew, the build system build, CI ci, vendored GPU stack third-party.
• Summary: lowercase start, imperative mood, no trailing period. Keep the whole subject line under 60 characters.

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.
• Assume reader has no access to any agentic coding sessions

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.