AI-Agent Code Review for GitHub Pull Requests

Description:

This n8n workflow automates the process of reviewing code changes in GitHub pull requests using an OpenAI-powered agent.

It connects your GitHub repo, extracts modified files, analyzes diffs, and uses an AI agent to generate a code review based on your internal code best practices (fed from a Google Sheet).

It ends by posting the review as a comment on the PR and tagging it with a visual label like ✅ Reviewed by AI.

🔧 What It Does

1. Triggered on PR creation

2. Extracts code diffs from the PR

3. Formats and feeds them into an OpenAI prompt

4. Enriches the prompt using a Google Sheet of Swift best practices

5. Posts an AI-generated review as a comment on the PR

6. Applies a PR label to visually mark reviewed PRs

✅ Prerequisites

Before deploying this workflow, ensure you have the following:

• n8n Instance (Self-hosted or Cloud)
• GitHub Repository with PR activity
• OpenAI API Key for GPT-4o, GPT-4-turbo, or GPT-3.5
• GitHub OAuth App (or PAT) connected to n8n to post comments and access PR diffs
• (Optional) Google Sheets API credentials if using the code best practices lookup node.

⚙️ Setup Instructions

1. Import the Workflow in n8n, click on Workflows → Import from file or JSON Paste or upload the JSON code of this template

2. Configure Triggers and Connections

🔁 GitHub Trigger

• Node: PR Trigger
• Repository: Select the GitHub repo(s) to monitor
• Events: Set to pull_request
• Auth: Use GitHub OAuth2 credentials

📥 HTTP Request

Node: Get file's Diffs from PR

No authentication needed; it uses dynamic path from trigger

🧠 OpenAI Model

• Node: OpenAI Chat Model

• Model: Select gpt-4o, gpt-4-turbo, or gpt-3.5-turbo

• Credential: Provide your OpenAI API Key

🧑‍💻 Code Review Agent

Node : Code Review Agent Connected to OpenAI and optionally to tools like Google Sheets

💬 GitHub Comment Poster

Uses GitHub API to post review comments back on PR Node: GitHub Robot Credential: Use the agent Github account (OAuth or PAT) Repo : Pick your owen Github Repository

🏷️ PR Labeler (optional)

Adds label ReviewedByAI after successful comment

Node: Add Label to PR Label : you ca customize the label text of your owen tag.

📊 Google Sheet Best Practices config (optional)

Connects to a Google Sheet for coding guideline lookups, we can replace Google sheet by another tool or data base

• First prepare your best practices list with the clear description and the code bad/good examples
• Add al the best practices in your Google Sheet
• Configure the Code Best Practices node in the template :

Credential : Use your Google Sheet account by OAuth2

URL : Add your Google Sheet document URL

Sheet : Add the name of the best practices sheet