# PR Reviewer

An on-demand pull request review workspace. Paste a GitHub PR URL in chat, and the reviewer fetches the code, analyzes it for bugs, security issues, and style problems, then posts an inline review directly on the PR.

When triggered, it:

- **Reads the PR** — fetches metadata: title, body, author, base/head branches, and changed files
- **Reads each changed file** — pulls the current file contents to understand full context, not just the diff
- **Analyzes the changes** for:
  - Correctness and logic bugs
  - Security issues (injection, auth, secret exposure)
  - Performance concerns
  - Code style and maintainability
  - Missing tests or edge cases
- **Posts an inline GitHub review** — specific comments at the relevant file and line, plus a summary verdict (APPROVE / REQUEST_CHANGES / COMMENT)

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![github-pr-reviewer output](https://raw.githubusercontent.com/friday-platform/friday-studio-examples/main/assets/github-pr-reviewer/output.png)

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## Setup

### 1. Download Friday

1. Go to [hellofriday.ai](https://hellofriday.ai) and download the macOS installer
2. Open the DMG and drag Friday to your Applications folder
3. Launch Friday and complete the initial setup

### 2. Import the workspace

1. Open Friday and go to **Discover Spaces**
2. Find this workspace and click it
3. Click **Add Space**

### 3. Connect GitHub

GitHub PR Reviewer uses the GitHub MCP server, which needs a personal access token to query your PRs and review requests.

**Generate a token**

1. Go to [github.com/settings/tokens](https://github.com/settings/tokens)
2. Click **Generate new token (classic)**
3. Give it a name (e.g. `friday-digest`)
4. Select the following scopes:
   - `repo` — to read pull requests across your repos
   - `read:user` — to resolve your GitHub username automatically
5. Click **Generate token** and copy it — you won't see it again

**Connect it in Friday**

1. Open the imported workspace and start a chat
2. Friday will detect that GitHub needs credentials and surface a **Connect GitHub** prompt
3. Paste your token when asked
4. You're connected — no further setup needed

### 4. Run your first review

Once GitHub is connected, open the workspace, start a chat, and paste in any PR URL. The reviewer will fetch the code, analyze it, and post the review directly to the PR.

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## What the review looks like

The reviewer posts directly to the GitHub PR as a formal review, with:

- Inline comments on specific lines with explanations and suggestions
- A summary comment with an overall verdict and key findings grouped by severity
- A clear APPROVE, REQUEST_CHANGES, or COMMENT review state

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## How to use it

Trigger the `review-pr` signal from the Friday UI and paste in the PR URL when prompted.

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## How it works

![github-pr-reviewer workspace overview in Friday](https://raw.githubusercontent.com/friday-platform/friday-studio-examples/main/assets/github-pr-reviewer/how-it-works.png)

| Component | Role |
|---|---|
| `pr-reviewer` agent | LLM agent (Claude Opus 4.6) that reads the PR, analyzes changes, and posts the inline review |
| `review-pr-job` job | Single-state FSM that runs the `pr-reviewer` agent with the provided PR URL |
| `review-pr` signal | HTTP signal that accepts a `pr_url` and starts the review job |
| `github` MCP server | Provides PR read, file contents, review write, and comment tools |

The `review-pr` HTTP signal fires the `review-pr-job` FSM, which immediately runs the `pr-reviewer` agent. The agent calls the GitHub MCP tools in sequence: read PR → read files → create pending review → add inline comments → submit.

### GitHub tools used

- `github/pull_request_read` — fetches PR metadata
- `github/list_commits` — lists commits in the PR
- `github/get_file_contents` — reads current file contents
- `github/pull_request_review_write` — creates and submits the review
- `github/add_comment_to_pending_review` — adds inline comments to the pending review
- `github/add_issue_comment` — posts general comments if needed
- `github/search_code` — searches the codebase for context when needed

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## Notes

- The reviewer uses **Claude Opus 4.6** at temperature 0.3 — thorough and consistent, not creative.
- It reads full file contents, not just the diff, so it can spot issues that only make sense in context.
- Reviews are posted under the GitHub account you connected — make sure that account has write access to the repo.
- The reviewer will not invent findings. If the code looks clean, it says so and approves.
- There is no schedule — every review is triggered manually via the signal or HTTP endpoint.