Slack Channel for the Claude Code

Two-way Slack ↔ Claude Code bridge. Chat with Claude from Slack DMs and channels, just like you'd chat in the terminal.

Research Preview — Channels require Claude Code v2.1.80+ and claude.ai login.

How It Works

Slack workspace (cloud)
    ↕ WebSocket (Socket Mode — outbound only, no public URL)
server.ts (local MCP server, spawned by Claude Code)
    ↕ stdio (MCP transport)
Claude Code session

Socket Mode means no public URL needed — works behind firewalls, NAT, anywhere.

Quick Start

1. Create a Slack App

1. Go to api.slack.com/apps → Create New App → From scratch
2. Socket Mode: Settings → Socket Mode → Enable → Generate App-Level Token (xapp-...) with connections:write scope
3. Event Subscriptions: Enable → Subscribe to bot events:
   • message.im — DMs
   • message.channels — public channels
   • message.groups — private channels
   • app_mention — @ mentions
4. Bot Token Scopes (OAuth & Permissions):
   • chat:write — send messages
   • channels:history — read public channels
   • groups:history — read private channels
   • im:history — read DMs
   • reactions:write — add reactions
   • files:read — download shared files
   • files:write — upload files
   • users:read — resolve display names
5. Install to Workspace → Copy Bot Token (xoxb-...)

2. Configure Tokens

/slack-channel:configure xoxb-your-bot-token xapp-your-app-token

3. Run

Pick your runtime:

Option A: Bun (recommended)

cd slack && bun install
# Current (claude-code-plugins marketplace):
claude --channels plugin:slack-channel@claude-code-plugins
# Future (after upstream approval):
# claude --channels plugin:slack-channel@claude-plugins-official

Option B: Node.js / npx

cd slack && npm install
# In .mcp.json, change command to: "npx", args: ["tsx", "server.ts"]
claude --channels plugin:slack-channel@claude-code-plugins

Option C: Docker

cd slack && docker build -t claude-slack-channel .
# In .mcp.json, change command to: "docker", args: ["run", "--rm", "-i", "-v", "~/.claude/channels/slack:/state", "claude-slack-channel"]
claude --channels plugin:slack-channel@claude-code-plugins

4. Pair Your Account

1. DM the bot in Slack — you'll get a 6-character pairing code
2. In your terminal: /slack-channel:access pair <code>
3. You're connected. Chat away.

Access Control

See ACCESS.md for the full schema.

/slack-channel:access policy allowlist       # Only pre-approved users
/slack-channel:access add U12345678          # Add a user
/slack-channel:access remove U12345678       # Remove a user
/slack-channel:access channel C12345678      # Opt in a channel
/slack-channel:access channel C12345678 --mention  # Require @mention
/slack-channel:access status                 # Show current config

Security

• Sender gating: Every inbound message hits a gate. Ungated messages are silently dropped before reaching Claude.
• Outbound gate: Replies only work to channels that passed the inbound gate.
• File exfiltration guard: Cannot send .env, access.json, or other state files through the reply tool.
• Prompt injection defense: System instructions explicitly tell Claude to refuse pairing/access requests from Slack messages.
• Bot filtering: All bot_id messages are dropped (prevents bot-to-bot loops).
• Link unfurling disabled: All outbound messages set unfurl_links: false, unfurl_media: false.
• Token security: .env is chmod 0o600, never logged, never in tool results.
• Static mode: Set SLACK_ACCESS_MODE=static to freeze access at boot (no runtime mutation).

Development

# Dev mode (bypasses plugin allowlist):
claude --dangerously-load-development-channels server:slack

One-Pager & System Analysis

Full project one-pager and operator-grade system analysis

Contributors

• @jeremylongshore — author
• @maui-99 — security hardening (v0.3.0)

License

MIT