name: pr-description
description: Write GitHub Pull Request descriptions from branch commits. Use when user asks to write a PR description, create a PR summary, or document changes for a pull request. Analyzes git commits and diffs to produce structured PR documentation.

PR Description Writer

Generate structured PR descriptions from branch commits.

Workflow

1. Get commits: git log --oneline origin/main..HEAD (fallback to HEAD~10..HEAD)
2. Get each commit's details: git show <hash> --stat --format="%H%n%s%n%b"
3. Get each commit's diff: git diff <hash>^..<hash>
4. Write PR description following the output format below

Output Format

1. Title

Single line. Use most meaningful commit subject or synthesize one. Keep short and technical.

2. Summary (2-5 bullets)

High-level changes. Each bullet concrete and verifiable.

3. Why (1-4 bullets)

Motivation, problem, or user impact. Tie to reliability, security, performance, DX, or product needs.

4. Commit-by-commit details

For EACH commit, add subsection with exact subject as heading:

What:
1-3 bullets describing concrete changes

Why:
1-2 bullets explaining motivation/tradeoffs

Notes: (optional) only for risk, migration, follow-up, or nuance

Rules:
- Preserve commit subject exactly as written
- If commit has a meaningful description use that
- If commit is noisy (formatting, rename), say so briefly
- Related commits: document each, keep later ones shorter ("follow-up", "fixup")

5. Testing

Checklist of what was done. If none provided, infer likely checks and label "Suggested".

6. Risk and rollout (2-6 bullets)

• What could break
• Where to watch
• Rollback plan (1 line)
• If breaking change, include BREAKING CHANGE callout

7. Screenshots/logs (optional)

Only if UI, behavior, or observability changed.

Style

• Direct and technical. No marketing tone.
• No fluff or jokes.
• Short sentences. Prefer bullets over paragraphs.
• Do not invent facts. Say "Likely" or "Inferred" if uncertain.