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Channels

Channels let Builder-created agents reach users outside the Mastra server. Register a channel provider on Mastra.channels and the Builder exposes the channel as an integration option for every agent.

Slack is currently the only supported channel.

Quickstart​

Install the Slack provider:

npm install @mastra/slack

Register SlackProvider on Mastra.channels:

TypeScriptsrc/mastra/index.ts
import { Mastra } from '@mastra/core/mastra'
import { MastraEditor } from '@mastra/editor'
import { createBuilderAgent } from '@mastra/editor/ee'
import { SlackProvider } from '@mastra/slack'

export const mastra = new Mastra({
  storage,
  channels: {
    slack: new SlackProvider({
      refreshToken: process.env.SLACK_APP_CONFIG_REFRESH_TOKEN,
      baseUrl: process.env.SLACK_BASE_URL,
    }),
  },
  agents: { builderAgent: createBuilderAgent() },
  editor: new MastraEditor({
    builder: { enabled: true },
  }),
})

The Slack provider handles app creation, OAuth, slash commands, and message routing for every Builder-created agent that opts in.

Configuration​

SlackProvider requires one environment variable and accepts one optional override:

  • SLACK_APP_CONFIG_REFRESH_TOKEN (required): The refresh token from your Slack app configuration tokens, available under Your App Configuration Tokens on api.slack.com/apps. The refresh token doesn't expire, but the access tokens it issues rotate every 12 hours and are auto-persisted to Mastra.storage.
  • baseUrl (optional): The public URL Slack should send events and OAuth callbacks to. Defaults to the running Mastra server's host and port (for example, http://localhost:4111 in local development). Pass baseUrl explicitly when the public URL differs from the server's resolved address: typically a tunnel for local development (cloudflared tunnel --url http://localhost:4111) or a deployed URL in production.

Storage requirement​

SlackProvider requires a persistent storage backend on the Mastra instance. Without storage, rotated tokens and app installations are lost on restart.