Write PR

Turn the current branch's changes into a PR title and body that match the project's existing conventions. Analyze git history and diffs for intent, not just file names.

Use this skill when

• Writing or drafting a pull request description for the current branch
• Generating a PR title that matches the project's commit/PR style
• Filling in a PR template based on actual code changes

Do not use this skill when

• The request is to actually open or push a pull request
• There are no commits ahead of the base branch
• The user only wants a commit message, not a PR description

This skill is read-only. Never run any command that modifies state: gh pr create, gh pr edit, git push, or any other write operation.

Context

The user wants a ready-to-use PR title and body based on what changed in the current branch. Focus on intent and impact, not raw diff output. Respect the project's existing PR style.

Instructions

Step 1: Detect Base Branch

If $ARGUMENTS is provided, use it as the base branch.

Otherwise, auto-detect in this order:

1. Run git symbolic-ref refs/remotes/origin/HEAD 2>/dev/null — extract branch name (e.g., origin/main → main)
2. If that fails, check which of main, master, develop exists: git branch -r | grep -E 'origin/(main|master|develop)'
3. Use the first match found

Step 2: Collect Change Information

Run these commands in order:

git log <base>..<HEAD> --oneline
git diff <base>...<HEAD> --stat
git diff <base>...<HEAD> --shortstat

Use --shortstat output (e.g., 12 files changed, 340 insertions(+), 50 deletions(-)) to determine diff size:

• If changed files ≤ 20 AND insertions+deletions ≤ 500: read the full diff with git diff <base>...<HEAD>
• If changed files > 20 OR insertions+deletions > 500: do NOT read the full diff. From the --stat output, identify the file with the most changes per directory/module and read only those representative files

Step 3: Find PR Template

This step is mandatory. Do not skip or assume the file does not exist.

Attempt to read all paths below in parallel using a file read tool:

• .github/PULL_REQUEST_TEMPLATE.md
• .github/pull_request_template.md
• docs/pull_request_template.md
• PULL_REQUEST_TEMPLATE.md

Also check if .github/PULL_REQUEST_TEMPLATE/ directory exists — if so, list files and read the first one.

Use the first path that successfully returns content.

If a template file is successfully read:

• Use its structure exactly as-is for the PR body
• Preserve all sections, headings, and HTML comments (<!-- ... -->) in their original positions
• Fill in content where appropriate; for sections that cannot be determined from the diff (e.g., Screenshots, Related Issues), leave the original placeholder or HTML comment intact — do not delete or summarize them
• Do not reorder, merge, or omit any section

If all paths fail (file not found): use this default structure:

## Summary
<!-- What does this PR do and why? -->

## Changes
<!-- Key changes made -->

## Test Plan
<!-- How was this tested? -->

Step 4: Identify PR Title Style

Run:

gh pr list --state merged --limit 10 --json title 2>/dev/null

If gh returns results, analyze the title patterns (e.g., feat: ..., [PROJ-123] ..., Fix: ...).

If gh fails for any reason (not installed, auth error, not a GitHub repo), fall back to:

git log --oneline -20

Extract the dominant pattern from commit messages.

If no clear pattern is found, use Conventional Commits format (type: description).

Step 5: Write PR Content

Title:

• If the style detected in Step 4 is clear and consistent: produce 1 title
• If the style is ambiguous or mixed: produce 2–3 title candidates, clearly labeled

PR Body:

• Use the template structure from Step 3
• Fill each section based on the change analysis from Step 2
• Focus on why the change was made, not just what files changed
• Flag these explicitly if present in the diff:
  • Breaking changes (API/interface changes, removed fields)
  • New dependencies added
  • Architecture or structural changes
• Do not paste raw diff or file lists into the body
• For sections that cannot be filled (e.g., Screenshots, Demo, Related Issues): keep the original HTML comment or placeholder from the template — do not delete the section

Output Format

Present the output in this order:

Title

<single best title>

(If ambiguous, list alternatives labeled Alt 1, Alt 2)

PR Body

<filled-in PR body — exact template structure preserved>

Branch: <base> ← <current> · Commits: N · Files changed: N