GitHub PR Reviewer

A ChatGPT app that helps you review GitHub Pull Requests directly from within ChatGPT conversations. Built using OpenAI's Apps SDK with the Model Context Protocol (MCP).

Features

• Connect GitHub - OAuth login to connect your GitHub account
• List Pull Requests - View PRs you authored, need to review, or are involved in
• Get PR Context - Full PR details including files changed, diffs, and metadata
• Post Comments - Add general comments or inline comments on specific files/lines
• Approve PRs - Approve pull requests with optional comment
• Request Changes - Request changes with feedback
• Idempotency Protection - Prevents duplicate comments on retries
• OAuth 2.1 Compliant - Full MCP authorization spec with PKCE and discovery endpoints

---

MCP Tools

1. check_github_auth_status

Connect and check GitHub authentication status.

Input: None

Output (not authenticated):

{
  "authenticated": false,
  "authUrl": "https://github.com/login/oauth/authorize?..."
}

Output (authenticated):

{
  "authenticated": true,
  "user": { "login": "username", "name": "Full Name" }
}

---

2. list_pull_requests

List pull requests with priority cascade.

Input:

{
  "username": "octocat"  // Optional: filter by author
}

Default behavior (no username):

1. First shows PRs where YOU are the author
2. If none, shows PRs where you are a reviewer
3. If none, shows PRs where you are involved

Output:

{
  "pullRequests": [...],
  "searchType": "authored" | "reviewing" | "involved" | "user_authored",
  "totalCount": 5
}

---

3. get_pr_context

Get full context for a PR including files changed and diffs.

Input:

{
  "pr_name": "owner/repo#123"
}

Output:

{
  "pr": { "number": 123, "title": "...", "author": "..." },
  "description": "PR description...",
  "files": [
    { "filename": "src/index.ts", "status": "modified", "additions": 10, "deletions": 5, "patch": "..." }
  ],
  "commits": 3,
  "additions": 50,
  "deletions": 20
}

---

4. post_review_comments

Post review comments to a PR. Supports general and inline comments.

Input:

{
  "pr_name": "owner/repo#123",
  "comments": [
    { "body": "Looks good!" },
    { "body": "Use async here", "path": "src/index.ts", "line": 42 }
  ],
  "event": "COMMENT" | "APPROVE" | "REQUEST_CHANGES",
  "idempotency_key": "unique-key-123"
}

Comment Types:

• General comment: Only body - appears in PR conversation
• Inline comment: body + path + line - appears on specific line

Output:

{
  "success": true,
  "reviewId": 12345,
  "prUrl": "https://github.com/owner/repo/pull/123",
  "commentsPosted": 2
}

---

Example Prompts

1. Connect GitHub

Prompt	Output
"Connect my GitHub"	Shows GitHub OAuth login button
"Login to GitHub"	Shows GitHub OAuth login button

2. List Pull Requests

Prompt	Output
"List my PRs"	Lists your PRs in priority: authored → reviewing → involved
"Show my PRs for review"	Lists PRs where you are a reviewer
"List m-musaz PRs"	Lists all open PRs by m-musaz

3. Get PR Context

Prompt	Output
"Review owner/repo#123"	Returns full PR details: title, description, files, diffs
"Get context for PR 123"	Returns full PR details with code changes

4. Post Review Comments

Prompt	Output
"Add comment: 'Looks good!'"	Posts general comment on PR
"Comment on line 42 of src/index.ts: 'Use async here'"	Posts inline comment
"Approve this PR"	Approves the PR
"Request changes: 'Please add tests'"	Requests changes with feedback

---

Project Structure

chatgpt-github-pr-reviewer/
├── package.json                 # Root package with npm workspaces
├── server/
│   └── src/
│       ├── index.ts             # Express server with OAuth endpoints
│       ├── mcp-server.ts        # MCP protocol handler
│       ├── mcp-oauth.ts         # OAuth 2.1 implementation
│       ├── github-auth.ts       # GitHub OAuth logic
│       ├── github-api.ts        # GitHub API integration
│       ├── idempotency-service.ts # Duplicate prevention
│       ├── token-store.ts       # GitHub token storage
│       └── types.ts             # TypeScript types
└── widget/
    └── src/
        ├── GitHubWidget.tsx     # Main widget component
        └── components/          # UI components

---

Environment Variables

# GitHub OAuth (from GitHub Developer Settings)
GITHUB_CLIENT_ID=your_github_client_id
GITHUB_CLIENT_SECRET=your_github_client_secret
GITHUB_REDIRECT_URI=http://localhost:3000/github/callback

# Server
PORT=3000
NODE_ENV=development

# MCP OAuth (for ChatGPT authentication)
MCP_OAUTH_CLIENT_ID=chatgpt-mcp-client
MCP_OAUTH_CLIENT_SECRET=chatgpt-mcp-secret-key-2024

# Widget Base URL
WIDGET_BASE_URL=https://your-app.railway.app

---

GitHub OAuth App Setup

Step 1: Create GitHub OAuth App

1. Go to GitHub Developer Settings
2. Click "OAuth Apps" → "New OAuth App"
3. Fill in:
   • Application name: ChatGPT PR Reviewer
   • Homepage URL: https://your-app.railway.app
   • Authorization callback URL: https://your-app.railway.app/github/callback
4. Copy Client ID and Client Secret to .env

Step 2: Required Scopes

Scope	Purpose
read:user	Read user profile
read:org	Read organization/team membership
repo	Full repository access (required for posting reviews)

---

Local Development

# Install dependencies
npm install

# Create .env file
cp .env.example .env
# Edit .env with your GitHub OAuth credentials

# Start development server
npm run dev

---

Deployment

Railway

1. Connect your GitHub repo to Railway
2. Add environment variables:

   GITHUB_CLIENT_ID=your_client_id
   GITHUB_CLIENT_SECRET=your_client_secret
   GITHUB_REDIRECT_URI=https://your-app.railway.app/github/callback
   PORT=3000
   NODE_ENV=production
   WIDGET_BASE_URL=https://your-app.railway.app
   

---

ChatGPT Integration

1. Create a new ChatGPT App
2. Configure MCP:
   • Discovery URL: https://your-app.railway.app/.well-known/oauth-authorization-server
3. Test with: "Connect my GitHub" or "List my PRs"

---

Credits

Built with:

• OpenAI Apps SDK
• Model Context Protocol (MCP)
• GitHub REST API
• React
• Vite

---

Happy PR Reviewing!