Channel Bridge MCP

An independent messaging-channel bridge for Claude Code, built on MCP. The first adapter is Slack Socket Mode; Discord, Telegram, and Lark adapters are planned behind the same channel interface.

Architecture

Slack Events API (Socket Mode)
          |
          v
Access policy + thread gate
          |
          v
notifications/claude/channel ---> Claude Code
          ^                           |
          |                           v
      Slack Web API <--------- MCP tools

This is a channel MCP server, not a model proxy. Inbound messages are emitted with the experimental claude/channel capability. Outbound actions are MCP tools: reply, react, edit_message, fetch_messages, and download_attachment.

Related MCP server: Herald

Current behavior

• Only allowlisted Slack users and channels can trigger the bridge.

• A top-level channel message must mention the bot by default.

• Follow-up messages inside a thread started with the bot do not need another mention.

• Direct messages are accepted only from allowlisted users.

• Attachment metadata is delivered immediately; bytes are downloaded only when Claude calls download_attachment.

• Tokens and runtime state stay outside the repository.

Slack application

Create a Slack app with Socket Mode enabled.

Bot scopes:

• app_mentions:read

• channels:history

• chat:write

• files:read

• reactions:read

• reactions:write

• users:read

Bot events:

• app_mention

• message.channels

• message.im

Create an App-Level Token with connections:write.

Install

npm install
npm run build

Create the state directory:

mkdir -p ~/.claude/channels/channel-bridge
chmod 700 ~/.claude/channels/channel-bridge

Create ~/.claude/channels/channel-bridge/.env:

SLACK_BOT_TOKEN=xoxb-REPLACE_ME
SLACK_APP_TOKEN=xapp-REPLACE_ME

Then protect it:

chmod 600 ~/.claude/channels/channel-bridge/.env

Copy config/access.example.json to ~/.claude/channels/channel-bridge/access.json, replace the sample Slack IDs, and set mode 600.

Run with Claude Code

For local development, add this repository as a Claude Code plugin or register its .mcp.json, then launch Claude Code with the channel enabled:

claude --channels plugin:channel-bridge@your-marketplace

The exact install command depends on the marketplace/repository publishing method. During development, npm run dev can validate Slack connectivity and npm test validates the access gate.

Roadmap

• MCP channel capability and inbound Slack notifications

• Slack reply/react/edit/history/attachment tools

• Allowlist and mention/thread policy

• Pairing command and runtime access management

• Permission-request buttons from phone

• Discord adapter

• Telegram adapter

• Lark/Feishu adapter

• Adapter contract and conformance test suite

• Installable Claude Code marketplace package

Security

Never commit .env, bot tokens, downloaded attachments, or runtime state. Use a dedicated low-privilege bot for development. The bridge enforces both a user allowlist and a channel allowlist before delivering content to Claude.

License

MIT