# Chicane

*When Claude Code can't go straight, take the chicane.*

A Slack bridge for [Claude Code](https://docs.anthropic.com/en/docs/claude-code) — send coding tasks from Slack, get results back.

## Why "Chicane"?

In motorsport, a **chicane** is a sequence of tight turns that forces drivers off the straight line — an engineered detour that still gets you to the finish. When you can't go straight to your Claude Code session (you're away from your desk, on your phone, or just prefer a chat interface), **Chicane** is the engineered path through Slack. The session continues, the context is preserved, you just took a different route.

## How it works

```
Slack (Socket Mode) → Chicane → Claude Agent SDK
                    ← streaming events ←
```

Each Slack thread gets its own Claude Code session. The session persists for the life of the thread, so follow-up messages have full context. If the bot restarts, it reconnects to existing threads by scanning thread history or resuming via session IDs.

## Prerequisites

- **Python 3.11+**
- **[Claude Code](https://docs.anthropic.com/en/docs/claude-code)** installed and authenticated (the SDK reads your existing credentials)
- A **Slack workspace** where you can create apps

## Installation

```bash
pip install chicane
```

Or install from source:

```bash
git clone https://github.com/dinnyosz/chicane.git
cd chicane
pip install -e .
```

## Setup

The fastest way to get started is the guided setup wizard:

```bash
chicane setup
```

This walks you through creating a Slack app, getting your tokens, and writing the `.env` file — all in one step. Run it again any time to update your config.

Alternatively, you can set things up manually:

### 1. Create a Slack app

Follow the [Slack app setup guide](docs/slack-setup.md) to create and install a Slack app. You'll need the **Bot Token** (`xoxb-...`) and **App-Level Token** (`xapp-...`).

### 2. Configure environment variables

Chicane reads its `.env` from the platform config directory:

- **macOS:** `~/Library/Application Support/chicane/.env`
- **Linux:** `~/.config/chicane/.env` (or `$XDG_CONFIG_HOME/chicane/.env`)
- **Windows:** `%APPDATA%\chicane\.env`

You can create it manually:

```bash
# macOS
mkdir -p ~/Library/Application\ Support/chicane
cat <<'EOF' > ~/Library/Application\ Support/chicane/.env
SLACK_BOT_TOKEN=xoxb-your-bot-token
SLACK_APP_TOKEN=xapp-your-app-token
EOF

# Linux
mkdir -p ~/.config/chicane
cat <<'EOF' > ~/.config/chicane/.env
SLACK_BOT_TOKEN=xoxb-your-bot-token
SLACK_APP_TOKEN=xapp-your-app-token
EOF
```

On Windows (PowerShell):
```powershell
New-Item -ItemType Directory -Force -Path "$env:APPDATA\chicane"
@"
SLACK_BOT_TOKEN=xoxb-your-bot-token
SLACK_APP_TOKEN=xapp-your-app-token
"@ | Set-Content "$env:APPDATA\chicane\.env"
```

Or just run `chicane setup` — it writes the file to the correct location for you.

See [Configuration reference](#configuration-reference) for all options.

### 3. Start the bot

```bash
chicane run
```

Chicane uses a persistent WebSocket connection (Slack Socket Mode) to receive events in real time. If your OS puts the machine to sleep, the connection drops and the bot goes offline. On macOS, use `caffeinate` to prevent sleep while the bot is running:

```bash
caffeinate -i chicane run
```

On Linux, use `systemd-inhibit`:

```bash
systemd-inhibit --what=idle chicane run
```

## Usage

- **@mention in a channel** &mdash; `@Chicane refactor the auth module` starts a new session in a thread
- **DM the bot** &mdash; send a message directly, no @mention needed
- **Thread follow-ups** &mdash; reply in the thread to continue the conversation with full context
- **Reconnect after restart** &mdash; Chicane automatically picks up existing threads when it restarts

## Handoff & MCP

Chicane supports handing off sessions between Claude Code on your desktop and Slack, and sending messages to Slack channels directly from Claude Code.

### MCP server (recommended)

Chicane ships with an MCP server that exposes `chicane_handoff` and `chicane_send_message` as tools Claude Code can call natively — no shell scripts or skills needed.

**If you installed from PyPI:**

```bash
claude mcp add chicane -- chicane-mcp
```

**For development (`pip install -e .`):**

A separate `chicane-mcp-dev` binary is provided so it can coexist with a PyPI-installed `chicane-mcp`:

```bash
claude mcp add chicane-dev -- chicane-mcp-dev
```

Once added, Claude Code discovers the tools automatically. You can say "hand this off to Slack" or "send an update to Slack" and Claude will use the MCP tools.

**Tools:**

| Tool | Description |
|---|---|
| `chicane_handoff` | Hand off the current session to Slack. Auto-detects session ID and channel from cwd. |
| `chicane_send_message` | Send a message to a Slack channel. Channel auto-resolved from cwd via `CHANNEL_DIRS`. |
| `chicane_init` | Install the Chicane skill and optionally auto-allow tools in `settings.local.json`. |

### CLI handoff

You can also hand off sessions via the CLI directly:

```bash
chicane handoff --summary "Refactoring the auth module, tests passing"
```

The session ID is auto-detected from Claude Code's history. The channel is resolved from your current working directory via the `CHANNEL_DIRS` mapping. When someone replies to the handoff message in Slack, Chicane resumes that exact Claude Code session with all prior context.

## CLI reference

```
chicane <command> [options]
```

| Command | Description |
|---|---|
| `setup` | Guided setup wizard (creates/updates `.env`) |
| `run` | Start the Slack bot |
| `handoff` | Post a handoff message to Slack |
| `help` | Show help message |

### `chicane setup`

Interactive setup wizard. Walks through creating a Slack app, collecting tokens, and writing `.env`. If a `.env` already exists, current values are shown as defaults — just press Enter to keep them.

### `chicane run`

Starts the Slack bot. Connects via Socket Mode and listens for messages.

### `chicane handoff`

| Flag | Required | Description |
|---|---|---|
| `--summary` | Yes | Summary text for the handoff message |
| `--session-id` | No | Claude session ID (auto-detected from `~/.claude/history.jsonl` if omitted) |
| `--channel` | No | Slack channel name (auto-resolved from cwd via `CHANNEL_DIRS` if omitted) |
| `--cwd` | No | Working directory to resolve channel from (defaults to `$PWD`) |
| `--questions` | No | Open questions to post as a thread reply |

## Configuration reference

All configuration is via environment variables, loaded from the `.env` file in the [platform config directory](#2-configure-environment-variables).

| Variable | Required | Default | Description |
|---|---|---|---|
| `SLACK_BOT_TOKEN` | Yes | &mdash; | Slack Bot User OAuth Token (`xoxb-...`) |
| `SLACK_APP_TOKEN` | Yes | &mdash; | Slack App-Level Token (`xapp-...`) with `connections:write` scope |
| `BASE_DIRECTORY` | No | &mdash; | Default working directory for Claude sessions |
| `ALLOWED_USERS` | Yes | (none) | Comma-separated Slack user IDs that can use the bot. If empty, all messages are blocked. |
| `CHANNEL_DIRS` | No | &mdash; | Map channels to directories. Simple: `magaldi,frontend` (name = dir under `BASE_DIRECTORY`). Custom: `web=frontend,infra=/opt/infrastructure` |
| `CLAUDE_MODEL` | No | SDK default | Claude model override (e.g. `sonnet`, `opus`) |
| `CLAUDE_PERMISSION_MODE` | No | `acceptEdits` | Permission mode (`acceptEdits`, `dontAsk`, `bypassPermissions`) |
| `CLAUDE_ALLOWED_TOOLS` | No | &mdash; | Comma-separated tool rules (e.g. `Bash(npm run *),Read`) |
| `CLAUDE_DISALLOWED_TOOLS` | No | &mdash; | Comma-separated tools to disallow |
| `CLAUDE_SETTING_SOURCES` | No | `user,project,local` | Which settings to load (`user`, `project`, `local`) |
| `CLAUDE_MAX_TURNS` | No | &mdash; | Maximum agentic turns per request |
| `CLAUDE_MAX_BUDGET_USD` | No | &mdash; | Maximum spend per request in USD |
| `RATE_LIMIT` | No | `10` | Max messages per user per minute |
| `VERBOSITY` | No | `verbose` | Notification level (`minimal`, `normal`, `verbose`) |
| `LOG_DIR` | No | &mdash; | Directory for log files (required for `--detach` mode) |
| `LOG_LEVEL` | No | `INFO` | Log level (`DEBUG`, `INFO`, `WARNING`, `ERROR`) |
| `CHICANE_CONFIG_DIR` | No | Platform default | Override the config directory path |

## Authentication & usage terms

Chicane uses the [Claude Agent SDK](https://github.com/anthropics/claude-code-sdk-python), which spawns the Claude Code CLI as a subprocess. The CLI handles all authentication — Chicane itself never touches API keys or tokens.

The SDK supports several authentication methods:

| Method | How to configure |
|---|---|
| **API key** (recommended) | Set `ANTHROPIC_API_KEY` in your environment or chicane `.env` |
| **Claude Code login** | Run `claude` and log in — the SDK inherits your session |
| **Amazon Bedrock** | Set `CLAUDE_CODE_USE_BEDROCK=1` + AWS credentials |
| **Google Vertex AI** | Set `CLAUDE_CODE_USE_VERTEX=1` + GCP credentials |

**Important:** Anthropic's [legal and compliance docs](https://code.claude.com/docs/en/legal-and-compliance) state that OAuth authentication from Free, Pro, and Max plans is "intended exclusively for Claude Code and Claude.ai" and that using these credentials with the Agent SDK "is not permitted." For production deployments, use an API key from [console.anthropic.com](https://console.anthropic.com) or a supported cloud provider.

## Security & risk model

Chicane gives your Slack workspace access to a Claude Code session running on your machine. Understand the implications before deploying.

### Multi-user access = shared machine access

Every user in `ALLOWED_USERS` can instruct Claude to read files, run commands, and edit code in the configured working directories. This is equivalent to giving them shell access to your machine (scoped by the permission mode). Only add users you trust at that level.

### One set of credentials, multiple users

All Slack users interact through a single set of Claude credentials — whoever runs the bot. If you're using an API key, all usage is billed to that key. This is **not subscription sharing** (each user doesn't get their own Claude session with your subscription), but it does mean your API spend scales with the number of active users and threads.

If you use consumer OAuth (Pro/Max login) instead of an API key, having multiple users send requests through your subscription likely violates [Anthropic's terms](https://code.claude.com/docs/en/legal-and-compliance), which state that consumer plan limits "assume ordinary, individual usage."

### Permission modes

| Mode | What Claude can do | Risk |
|---|---|---|
| `acceptEdits` (default) | Auto-approve file edits; shell commands require pre-approved tool patterns | Moderate — users can modify files but not run arbitrary commands |
| `dontAsk` | Only use explicitly allowed tools; deny everything else | Low — tightly scoped to your allowlist |
| `bypassPermissions` | Everything, including arbitrary shell commands | High — equivalent to unrestricted shell access; restricted to single-user configurations |

`bypassPermissions` with multiple `ALLOWED_USERS` is blocked at startup. Even with a single user, only use it in isolated environments (containers, VMs).

### Session handoff trust model

When a session is handed off from Claude Code to Slack, anyone in the channel can see the session alias. Any allowed user who replies in that thread resumes the session with access to the original working directory. There is no per-session authentication — access control relies entirely on `ALLOWED_USERS`.

### Thread history and prompt injection

When Chicane cannot find a mapped session for a thread (e.g. the bot restarted and the handoff alias is missing), it falls back to rebuilding context by injecting the Slack thread history into Claude's prompt. Messages from non-allowed users are excluded, and Claude is instructed to treat the history as untrusted data. This is a defense-in-depth measure, not a cryptographic guarantee — treat public channels accordingly. When a session is successfully resumed via handoff alias, thread history injection does not occur.

### Recommendations

- **Use API key auth** for any deployment with multiple users
- **Use `dontAsk` mode** with a tight `CLAUDE_ALLOWED_TOOLS` list for the most restrictive setup
- **Set `CLAUDE_MAX_TURNS` and `CLAUDE_MAX_BUDGET_USD`** to bound cost and runaway sessions
- **Keep `ALLOWED_USERS` minimal** — every user is effectively a shell user on your machine
- **Prefer private channels** for threads containing sensitive code or session handoffs

## License

[Apache 2.0](LICENSE)
