| name | pr-review |
| description | Review a GitHub PR by fetching its diff, analyzing it with momus (expert reviewer), and producing structured inline comments with file paths, line numbers, and severity levels. MUST USE when the user shares a GitHub PR link and asks for a review, says "review this PR", "look at this pull request", "give me feedback on PR |
PR Review Skill
You review a GitHub PR end-to-end: fetch the diff, get expert analysis from momus, and post every review comment directly on the PR as inline GitHub comments. You do NOT stop after showing the summary — you MUST post the comments on GitHub before you are done.
Workflow
Step 1: Extract PR Information
Parse the PR identifier from the user's message:
- Full URL:
https://github.com/org/repo/pull/123 → extract number 123 and repo org/repo
- Short form:
PR #123 or #123 → use number directly
- If just a number with no repo context, infer from
gh repo view --json nameWithOwner -q '.nameWithOwner'
Step 2: Fetch PR Diff and Metadata
Run these commands (use --repo org/repo if the PR is in a different repo):
gh pr view <NUMBER> --json title,body,baseRefName,headRefName,files,additions,deletions,changedFiles,headRefOid
gh pr diff <NUMBER>
gh pr diff <NUMBER> --stat
gh repo view --json nameWithOwner -q '.nameWithOwner'
Save these for later — you need them to post comments:
PR_NUMBER = the PR numberCOMMIT_SHA = headRefOid from the metadataOWNER_REPO = nameWithOwner (e.g. juspay/hyperswitch-control-center)
Step 3: Send to Momus for Expert Review
Invoke momus synchronously (do NOT run in background — you need the result):
task(subagent_type="momus", run_in_background=false, load_skills=[], ...)
Prompt momus with:
Review the following GitHub Pull Request.
## PR Metadata
- Title: <title>
- Description: <body>
- Base: <baseRefName> → Head: <headRefName>
- Files changed: <changedFiles>, +<additions> -<deletions>
## Changed Files
<file list with stats>
## Full Diff
<complete diff>
## Instructions
For each issue found, return:
- file_path: exact relative path (e.g. src/components/Button.tsx)
- line_number: line in the NEW file (right side of diff, added/modified lines only)
- severity: critical | warning | suggestion | nitpick
- comment: clear, actionable description
- suggested_code: (optional) corrected snippet
Also return:
- summary: 2-3 sentence assessment
- verdict: approve | request_changes | comment_only
Return as JSON:
{
"summary": "...",
"verdict": "...",
"comments": [
{ "file_path": "...", "line_number": N, "severity": "...", "comment": "...", "suggested_code": "..." }
]
}
Step 4: Validate Momus Output
- Parse the JSON from momus
- Verify each comment has
file_path, line_number, severity, comment
- Drop comments referencing files not in the PR's changed files list
- Sort by severity: critical → warning → suggestion → nitpick
Step 5: Show Review Summary
Display to the user:
## PR Review: <title>
**Verdict**: <approve/request_changes/comment_only>
**Summary**: <summary>
### Critical (N)
- `file:line` — comment
### Warnings (N)
- `file:line` — comment
### Suggestions (N)
- `file:line` — comment
### Nitpicks (N)
- `file:line` — comment
Step 6: Post All Comments on GitHub
THIS STEP IS NOT OPTIONAL. After showing the summary, you MUST post every comment on the PR. Do not ask the user for confirmation — just post them.
6a. Validate lines are in the diff
For each comment, check the line is actually in the diff:
gh pr diff <PR_NUMBER> -- <FILE_PATH>
- Line appears as a
+ line on the right side → post as inline comment (Step 6b)
- Line is NOT in the diff → post as PR-level comment instead (Step 6c)
6b. Post inline comments
Comment bodies often contain backticks, pipes, quotes, newlines, and code fences that WILL break shell parsing if passed as -f body="...". You MUST write the JSON payload to a temp file and use --input to avoid parse errors.
For each comment, write a JSON file and post it:
cat > /tmp/pr_comment.json << 'JSONEOF'
{
"body": "<COMMENT_BODY>",
"commit_id": "<COMMIT_SHA>",
"path": "<FILE_PATH>",
"line": <LINE_NUMBER>,
"side": "RIGHT"
}
JSONEOF
gh api repos/<OWNER_REPO>/pulls/<PR_NUMBER>/comments \
--method POST \
--input /tmp/pr_comment.json
Building the body string: Construct <COMMENT_BODY> as a properly JSON-escaped string. Remember to escape:
" → \"- newlines →
\n
- backslashes →
\\
- tabs →
\t
For a comment WITH suggested_code, the body should be:
**[<SEVERITY>]** <COMMENT>\n\n```suggestion\n<SUGGESTED_CODE>\n```
For a comment WITHOUT suggested_code, the body is simply:
**[<SEVERITY>]** <COMMENT>
CRITICAL: Always use the heredoc + --input pattern. NEVER pass the body as a -f body="..." argument — it will break on any comment containing backticks, pipes, or quotes.
6c. Post PR-level comments
For comments where the line is NOT in the diff, or that have no file/line, also use a temp file:
cat > /tmp/pr_comment.json << 'JSONEOF'
{
"body": "**[<SEVERITY>]** `<FILE_PATH>:<LINE_NUMBER>` — <COMMENT>"
}
JSONEOF
gh api repos/<OWNER_REPO>/issues/<PR_NUMBER>/comments \
--method POST \
--input /tmp/pr_comment.json
6d. Post the overall review summary
After all inline comments are posted, post the verdict as a PR comment:
cat > /tmp/pr_comment.json << 'JSONEOF'
{
"body": "## Review Summary\n\n**Verdict**: <VERDICT>\n\n<SUMMARY>\n\n---\n_Automated review via momus_"
}
JSONEOF
gh api repos/<OWNER_REPO>/issues/<PR_NUMBER>/comments \
--method POST \
--input /tmp/pr_comment.json
Step 7: Report Results
After posting, show what happened:
## Comments Posted
### Inline Comments
- `src/Button.tsx:42` — "[critical] ..." ✓
- `src/helpers.js:15` — "[warning] ..." ✓
### PR-Level Comments
- Review summary ✓
### Downgraded (line not in diff)
- `src/client.ts:200` — posted as PR comment instead
### Failed
- `src/api.ts:30` — error: <reason>
If a comment fails to post, log the error and continue with the rest.
Error Handling
gh not authenticated → tell user to run gh auth login- Invalid PR number or repo → report error clearly
- Momus returns unparseable response → show raw output, ask to retry
- Individual comment fails to post → log error, continue with remaining
- All comments fail → suggest checking GitHub permissions
- Very large PR (50+ files / 2000+ lines) → split into batches, tell the user
Important
- Line numbers MUST be from the NEW file (right side of diff) — that's what GitHub expects
commit_id MUST be headRefOid — not any other commit- Preserve exact file paths from the diff — no normalizing
- Fetch the FULL diff, not just filenames — momus needs actual code to review
