JJ Commit Message Generator

Generate conventional commit messages for Jujutsu (jj) by analyzing diffs.

Instructions

When the user asks to create a commit message or commit changes:

1. Run tests first:

   • Detect test framework from project (package.json, Cargo.toml, pyproject.toml, etc.)
   • Run appropriate test command:
     • npm/yarn: npm test or yarn test
     • Rust: cargo test
     • Python: pytest or python -m pytest
     • Go: go test ./...
   • If tests fail:
     • Show failures to user
     • Ask: "Tests failing. Fix before commit, skip tests, or commit anyway?"
     • Only proceed with commit if user explicitly chooses to skip/ignore
   • If no test command found, proceed without testing

2. Gather context:

   • Run jj diff to see current changes
   • Run jj log -r @ to see the current change description
   • If working with specific revisions, use jj diff -r <revision>

3. Analyze changes:

   • Identify the type: feat, fix, refactor, docs, test, chore, style, perf
   • Determine scope if clear from file paths
   • Summarize the "why" (intent) not just "what" changed

4. Generate message: Format: <type>(<scope>): <subject>

   • Subject: imperative mood, lowercase, no period, < 72 chars
   • Body (optional): explain why, not what
   • Favor precision over verbosity

   Examples:

   • feat(ui): add dark mode toggle
   • fix(auth): prevent token refresh loop
   • refactor(api): simplify error handling

5. Handle immutable commits: If you get error: Commit ... is immutable:

   • Explain that the commit is immutable
   • Suggest running the command with --ignore-immutable flag
   • Ask user if they want to proceed with the flag

6. Execute commit:

   • Use jj describe -m "message" for current change
   • Or jj describe -r <revision> -m "message" for specific revision
   • If immutable and user approves, add --ignore-immutable

Tool access

allowed-tools:

• Bash
• Read
• Grep

Notes

• Keep messages concise and clear
• Focus on intent, not implementation details
• Follow conventional commit format strictly