pr-summary

name	pr-summary
description	Generate a PR summary from all commits since the branch diverged from a given parent branch, written to pr-summary.msg
allowed-tools	Bash, Read, Grep, Glob

/pr-summary — Generate PR Summary

Analyze all commits on the current branch since it diverged from the parent branch and write a summary to pr-summary.msg.

Arguments: $ARGUMENTS — the parent/base branch to diff against (e.g. main, dev, master). This argument is required.

Steps

1. Determine the fork point

If $ARGUMENTS is empty, ask the user to provide the parent branch (e.g. /pr-summary main). Do not assume a default.

Ensure pr-summary.msg is in the .gitignore in root of repo:

if [ ! -f .gitignore ] || ! grep -qF "pr-summary.msg" .gitignore; then
  echo "pr-summary.msg" >> .gitignore
fi

Find where the current branch forked from the provided parent branch:

BASE=$(git merge-base HEAD $ARGUMENTS)

2. Gather all commits since fork point

git log --reverse --pretty=format:"%h %s%n%b" $BASE..HEAD

Also run git diff $BASE..HEAD --stat to get a file-level change summary.

3. Read changed files for context

Read key changed files to understand what the commits actually do. Use git diff $BASE..HEAD for the full diff if needed, but focus on understanding the intent, not reciting code.

4. Write pr-summary.msg

Delete any existing pr-summary.msg first. Write the summary with this structure:

## Problems to Solve
<Describe the problems this PR addresses, based on commit messages and changed files. Focus on the "why" and "what", not the "how".>

## Summary
<1-3 bullet points describing the high-level purpose of this branch>

## Changes
<Bulleted list of specific changes, grouped logically>

## Test plan
<How to verify these changes work — mention relevant test commands, manual steps, or areas to check>

Keep it concise. Focus on why and what, not how. Group related commits into logical changes rather than listing every commit verbatim.

5. Open a pull request

After writing the summary, open a pull request on GitHub or your git hosting provider. Use the contents of pr-summary.msg as the PR description to provide reviewers with context and an overview of the changes. Create the PR with gh CLI tool. For example, if the current branch is feature-branch and the parent branch is main, you can run:

gh pr create --base main --head feature-branch --title "PR Summary" --body-file pr-summary.msg