preflight

# preflight

A local code review tool for AI-generated changes. Review diffs in the browser, comment on specific lines, and let your AI agent explain code and apply revisions — all before the work reaches formal review.

Preflight calls no LLM APIs. It exposes an [MCP](https://modelcontextprotocol.io/) server that your existing AI agent (Claude Code, Codex, OpenCode, etc.) connects to, so the agent can participate in review conversations directly.

## How It Works

```
You (browser) <-> Preflight <-> MCP <-> Your AI Agent
```

1. Start the server
2. Your agent creates a review via MCP (or you create one from the browser)
3. Review diffs, leave comments, ask for explanations
4. The agent responds, submits revisions, and the diff updates in place

## Install

**macOS (Homebrew):**

```bash
brew install winstanley-industries/preflight/preflight
```

**Linux:** Download a binary from [GitHub Releases](https://github.com/winstanley-industries/preflight/releases).

**From source:**

```bash
cargo build --release -p preflight-server
```

## Quick Start

```bash
# Start the server (default port 3000)
preflight serve

# Start on a different port
preflight serve --port 8080

# Discard existing state and start fresh
preflight serve --fresh
```

Then open http://127.0.0.1:3000 in your browser.

## MCP Configuration

The MCP server connects to a running preflight web server (default port 3000).

### Claude Code

**Via plugin (recommended):**

```bash
claude plugin marketplace add winstanley-industries/preflight
claude plugin install -s user preflight@preflight
```

**Via MCP manually:**

```bash
claude mcp add --scope user --transport stdio preflight -- preflight mcp
```

Or add to `.mcp.json`:

```json
{
  "mcpServers": {
    "preflight": {
      "command": "preflight",
      "args": ["mcp"]
    }
  }
}
```

### Codex

Add to `~/.codex/config.toml` (or `.codex/config.toml` in your project):

```toml
[mcp_servers.preflight]
command = "preflight"
args = ["mcp"]
```

### OpenCode

Add to `opencode.json`:

```json
{
  "mcp": {
    "preflight": {
      "type": "local",
      "command": ["preflight", "mcp"]
    }
  }
}
```

To use a non-default port, append `"--port", "8080"` to the args/command for any of the above.

## Usage

Once configured, ask your AI agent to create a review:

> "Send my changes to preflight for review"
>
> "Create a preflight review"

The agent will create a review via MCP. Open the preflight UI to review diffs, leave comments, and ask questions. The agent can respond to your comments and submit revisions.

**Tip:** Ask your agent to monitor the review in the background so it responds to your comments automatically.

### Claude Code Plugin

The plugin registers the MCP server and adds a `/preflight:review` slash command. Install it once and every Claude Code session will know how to participate in reviews without additional configuration.

```bash
claude plugin marketplace add winstanley-industries/preflight
claude plugin install -s user preflight@preflight
```

Running `/preflight:review` in Claude Code will:

1. Create (or resume) a review for your current branch
2. Optionally annotate non-trivial changes with explanations
3. Launch a background agent that monitors comments and responds to your questions in the Preflight UI
4. When you click "Request Revision" in the UI, the agent compiles the requested changes and applies them
5. Loop back — each revision starts a new round of discussion until you close the review

## Features

- Browser-based diff viewer with syntax highlighting
- Inline comment threads between you and your AI agent
- Agent-submitted revisions with interdiff to see what changed
- Revision timeline for navigating review history
- Real-time updates via WebSocket
- Single binary, no external dependencies

## CLI Reference

```
preflight serve [OPTIONS]    Start the web server (default command)
  --port <PORT>              Port to listen on [default: 3000]
  --fresh                    Discard existing state and start fresh

preflight mcp [OPTIONS]      Start the MCP stdio server
  --port <PORT>              Port of the running web server [default: 3000]
```

## Tech Stack

Rust (Axum) backend, Svelte 5 frontend, bundled into one binary via rust-embed.

## License

Apache-2.0