mattermost

Mattermost Channel for Claude Code

Bridge Mattermost messages to your Claude Code session. Self-hosted, private, two-way chat.

DM your Mattermost bot, and the message arrives in your Claude Code terminal. Claude reads it, does the work, and replies back in Mattermost.

Prerequisites

• Claude Code v2.1.80+ with channels support
• Bun runtime
• A Mattermost instance with a bot account and personal access token

Setup

1. Create a Mattermost bot

1. Go to System Console > Integrations > Bot Accounts and enable bot accounts
2. Go to Integrations > Bot Accounts > Add Bot Account
3. Give it a username (e.g., claude-bot) and role
4. Copy the generated access token

Alternatively, create a personal access token:

1. Go to Account Settings > Security > Personal Access Tokens
2. Create a token and copy it

2. Install the plugin

/plugin install mattermost@claude-plugins-official

Or for local development:

cd ~/claude-channel-mattermost
bun install

3. Configure credentials

/mattermost:configure https://mm.example.com xoxb-your-token-here

This saves to ~/.claude/channels/mattermost/.env.

4. Start with channels enabled

# Published plugin
claude --channels plugin:mattermost@claude-plugins-official

# Local development
claude --dangerously-load-development-channels server:mattermost

5. Pair your account

1. DM the bot on Mattermost — it replies with a 6-char code
2. In Claude Code: /mattermost:access pair <code>
3. Lock down access: /mattermost:access policy allowlist

Tools

Tool	Description
reply	Post a message (with optional threading and file attachments)
react	Add an emoji reaction (use names like thumbsup, no colons)
edit_message	Edit a previously sent post
download_attachment	Download a file attachment to local inbox
fetch_messages	Retrieve recent channel history

Access Control

See ACCESS.md for full documentation.

• DM policy: pairing (default), allowlist, or disabled
• Group channels: opt-in per channel with optional mention-gating
• Sender allowlist: only approved user IDs can push messages

State Directory

~/.claude/channels/mattermost/
  .env          — MATTERMOST_URL and MATTERMOST_TOKEN
  access.json   — allowlist, groups, pending pairings
  inbox/        — downloaded attachments
  approved/     — pairing approval signal files