Takes a GitHub PR URL or the current branch and writes a plain-English explanation of what it does and why, then posts it as a PR comment. Use when asked to explain a PR, summarize a pull request, write a plain-English description of a PR, add a summary comment to a PR, or understand what a PR changes. Trigger when a user says "explain this PR", "summarize this pull request", "what does this PR do", "add a comment explaining the PR", or shares a GitHub PR URL and asks what it does.
Takes a GitHub PR URL or the current branch and writes a plain-English explanation of what it does and why, then posts it as a PR comment. Use when asked to explain a PR, summarize a pull request, write a plain-English description of a PR, add a summary comment to a PR, or understand what a PR changes. Trigger when a user says "explain this PR", "summarize this pull request", "what does this PR do", "add a comment explaining the PR", or shares a GitHub PR URL and asks what it does.
compatibility
["claude-code","gemini-cli","github-copilot"]
author
OpenDirectory
version
1.0.0
Explain This PR
Read a GitHub pull request, understand what it changes, and write a plain-English explanation. Post it as a PR comment so reviewers have instant context.
Step 1: Check Setup
Confirm gh is authenticated:
gh auth status
If not authenticated: gh auth login and follow the prompts.
Confirm input. The user must provide one of:
A GitHub PR URL (e.g. https://github.com/owner/repo/pull/123)
A PR number in the current repo (e.g. )
#123
The keyword "current" to use the PR for the current branch
If no input, ask: "Which PR should I explain? Share the URL, PR number, or say 'current' for the active branch."
Write two paragraphs. Read each rule before writing.
Paragraph 1: What it does (technical)
One sentence per major change
Name the specific files, functions, or systems that changed
State the before/after if the diff makes it clear
Include concrete numbers if present in the diff (lines removed, tables dropped, endpoints added)
Active voice, present tense
Example:
Replaces the in-memory session cache in auth.middleware.ts with a Redis-backed cache (src/cache/redis.ts). Adds get, set, and invalidate methods to the new Redis module and wraps UserService.getById() with a 5-minute TTL. Removes the Map-based cache that was limited to a single process and caused session drift across multiple instances.
Paragraph 2: Why it matters (business/product impact)
Who benefits and how
What problem this solves or what risk it reduces
If the commit messages contain a "why", use that context
If there is no clear "why" in the diff or commits, omit this paragraph rather than guessing
Example:
Users hitting the /api/me endpoint under load were getting inconsistent session data across server instances, causing intermittent 401 errors. This change makes session state consistent across all instances and reduces database load by eliminating one query per authenticated request.
Rules for both paragraphs:
No em dashes — use a comma or period
No filler: "this PR", "this change", "as you can see"
No invented outcomes. Only state impacts that are directly visible in the diff or commit messages
If the PR is a pure refactor with no behavior change, say that explicitly: "Refactors X to Y with no change in observable behavior."
Under 150 words total
Step 4: Self-QA
Before posting, check:
Paragraph 1 names specific files or functions from the diff
No invented metrics or outcomes
No em dashes
No filler phrases
Under 150 words total
If no clear "why" exists, paragraph 2 is omitted rather than guessing
Fix any violation before posting.
Step 5: Post as PR Comment
Present the explanation to the user. Ask: "Ready to post this as a PR comment, or would you like to edit it first?"
On confirmation, pass the body via stdin to handle backticks, quotes, and newlines safely:
