pr-summarizer

name	pr-summarizer
description	Use when opening a PR — produces a clean PR description (what / why / how to verify / risks) from a branch diff against base.
version	0.1.0
status	experimental
risk	low
tags	["engineering","read-only","writes-files"]

PR Summarizer

When to use

• Just before opening a PR
• After force-pushing a substantive update to an existing PR (refresh description)

When NOT to use

• Drafts the user is still iterating on (the summary will go stale immediately)
• Massive diffs (> 1000 lines) — ask the user to scope first

Inputs

Name	Type	Required	Notes
base	string	no	default origin/main
branch	string	no	default current HEAD

Outputs

A markdown PR body with sections: Summary, Why, How tested, Risks, Linked.

Workflow

1. git diff <base>...HEAD --stat and git log <base>..HEAD --oneline to see scope
2. git diff <base>...HEAD for content
3. Group changes by area (one bullet per logical concern, not per file)
4. Pull "why" from commit messages + linked tickets if mentioned
5. Identify test artifacts touched; surface as How tested (or flag if none)
6. Risks: any High-risk paths touched? auth, billing, migrations? mention.
7. Linked: parse Fixes # / Refs # from commits

References

• references/pr-template.md

Success criteria

• Description ≤ 25 lines
• Every "why" claim is supported by a commit message or visible in the diff
• Risks section honest about unknowns ("untested in production data shape")

Failure modes

• No commit messages worth quoting → "Why" sourced from diff only; flag this
• Diff touches secrets / .env* → STOP and surface; PR shouldn't include them