GitHub PR Review

Post structured code review feedback using the GitHub API with inline comments on specific lines.

Key Rule: One API Call

Bundle ALL comments into a single review API call. Do not post comments individually.

Posting a Review

Use the GitHub CLI (gh) with a JSON input file. The GITHUB_TOKEN is automatically available.

Important: Always use --input with a JSON file instead of -F flags. This avoids shell quoting issues with special characters in comment bodies (quotes, backticks, newlines, etc.) and eliminates the need for complex heredoc scripts.

Step 1: Create a JSON file

cat > /tmp/review.json << 'EOF'
{
  "commit_id": "{commit_sha}",
  "event": "COMMENT",
  "body": "Brief 1-3 sentence summary.",
  "comments": [
    {
      "path": "path/to/file.py",
      "line": 42,
      "side": "RIGHT",
      "body": "🟠 Important: Your comment here."
    },
    {
      "path": "another/file.js",
      "line": 15,
      "side": "RIGHT",
      "body": "🟡 Suggestion: Another comment."
    }
  ]
}
EOF

Step 2: Post the review

gh api -X POST repos/{owner}/{repo}/pulls/{pr_number}/reviews --input /tmp/review.json

Parameters

Parameter	Description
`commit_id`	Commit SHA to comment on (use `git rev-parse HEAD`)
`event`	`COMMENT`, `APPROVE`, or `REQUEST_CHANGES`
`path`	File path as shown in the diff
`line`	Line number in the NEW version (right side of diff)
`side`	`RIGHT` for new/added lines, `LEFT` for deleted lines
`body`	Comment text with priority label

Multi-Line Comments

For comments spanning multiple lines, add start_line to specify the range:

{
  "path": "path/to/file.py",
  "start_line": 10,
  "line": 12,
  "side": "RIGHT",
  "body": "🟡 Suggestion: Refactor this block:\n\n```suggestion\nline_one = \"new\"\nline_two = \"code\"\nline_three = \"here\"\n```"
}

Important: The suggestion must have the same number of lines as the range (e.g., lines 10-12 = 3 lines).

Priority Labels

Start each comment with a priority label. Minimize nits - leave minor style issues to linters.

Label	When to Use
🔴 Critical	Must fix: security vulnerabilities, bugs, data loss risks
🟠 Important	Should fix: logic errors, performance issues, missing error handling
🟡 Suggestion	Worth considering: significant improvements to clarity or maintainability
🟢 Nit	Optional: minor style preferences (use sparingly)
🟢 Acceptable	Pragmatic choice: acknowledged trade-off that is reasonable given constraints or out of scope for this PR

Example:

🟠 Important: This function doesn't handle None, which could cause an AttributeError.

```suggestion
if user is None:
    raise ValueError("User cannot be None")


## GitHub Suggestions

For small code changes, use the suggestion syntax for one-click apply:

~~~
```suggestion
improved_code_here()


Use suggestions for: renaming, typos, small refactors (1-5 lines), type hints, docstrings.

Avoid for: large refactors, architectural changes, ambiguous improvements.

## Finding Line Numbers

```bash
# From diff header: @@ -old_start,old_count +new_start,new_count @@
# Count from new_start for added/modified lines

grep -n "pattern" filename     # Find line number
head -n 42 filename | tail -1  # Verify line content
```

## Fallback: curl

If `gh` is unavailable, use curl with the JSON file:

```bash
curl -X POST \
  -H "Authorization: token $GITHUB_TOKEN" \
  -H "Accept: application/vnd.github+json" \
  "https://api.github.com/repos/{owner}/{repo}/pulls/{pr_number}/reviews" \
  -d @/tmp/review.json
```

## Summary

1. Analyze the code and identify important issues (minimize nits)
2. Write review data to a JSON file (e.g., `/tmp/review.json`)
3. Post **ONE** review using `gh api --input /tmp/review.json`
4. Use priority labels (🔴🟠🟡🟢) on every comment
5. Mark pragmatic trade-offs as 🟢 **Acceptable** - don't block PRs for out-of-scope improvements
6. Use suggestion syntax for concrete code changes
7. Keep the review body brief (details go in inline comments)
8. If no issues: post a short message

github-pr-review