Mattermost (plugin)

Status: supported via plugin (bot token + WebSocket events). Channels, groups, and DMs are supported. Mattermost is a self-hostable team messaging platform; see the official site at mattermost.com for product details and downloads.

Plugin required

Mattermost ships as a plugin and is not bundled with the core install.

Install via CLI (npm registry):

openclaw plugins install @openclaw/mattermost

Local checkout (when running from a git repo):

openclaw plugins install ./path/to/local/mattermost-plugin

If you choose Mattermost during setup and a git checkout is detected, OpenClaw will offer the local install path automatically.

Quick setup

1. Install the Mattermost plugin.
2. Create a Mattermost bot account and copy the bot token.
3. Copy the Mattermost base URL (e.g., https://chat.example.com).
4. Configure OpenClaw and start the gateway.

Minimal config:

{
  channels: {
    mattermost: {
      enabled: true,
      botToken: "mm-token",
      baseUrl: "https://chat.example.com",
      dmPolicy: "pairing",
    },
  },
}

Native slash commands

Native slash commands are opt-in. When enabled, OpenClaw registers oc_* slash commands via the Mattermost API and receives callback POSTs on the gateway HTTP server.

{
  channels: {
    mattermost: {
      commands: {
        native: true,
        nativeSkills: true,
        callbackPath: "/api/channels/mattermost/command",
        // Use when Mattermost cannot reach the gateway directly (reverse proxy/public URL).
        callbackUrl: "https://gateway.example.com/api/channels/mattermost/command",
      },
    },
  },
}

Notes:

• native: "auto" defaults to disabled for Mattermost. Set native: true to enable.
• If callbackUrl is omitted, OpenClaw derives one from gateway host/port + callbackPath.
• For multi-account setups, commands can be set at the top level or under channels.mattermost.accounts.<id>.commands (account values override top-level fields).
• Command callbacks are validated with per-command tokens and fail closed when token checks fail.
• Reachability requirement: the callback endpoint must be reachable from the Mattermost server.
• Mattermost egress allowlist requirement:

Environment variables (default account)

Set these on the gateway host if you prefer env vars:

• MATTERMOST_BOT_TOKEN=...
• MATTERMOST_URL=https://chat.example.com

Env vars apply only to the default account (default). Other accounts must use config values.

Chat modes

Mattermost responds to DMs automatically. Channel behavior is controlled by chatmode:

• oncall (default): respond only when @mentioned in channels.
• onmessage: respond to every channel message.
• onchar: respond when a message starts with a trigger prefix.

Config example:

{
  channels: {
    mattermost: {
      chatmode: "onchar",
      oncharPrefixes: [">", "!"],
    },
  },
}

Notes:

• onchar still responds to explicit @mentions.
• channels.mattermost.requireMention is honored for legacy configs but chatmode is preferred.

Threading and sessions

Use channels.mattermost.replyToMode to control whether channel and group replies stay in the main channel or start a thread under the triggering post.

• off (default): only reply in a thread when the inbound post is already in one.
• first: for top-level channel/group posts, start a thread under that post and route the conversation to a thread-scoped session.
• all: same behavior as first for Mattermost today.
• Direct messages ignore this setting and stay non-threaded.

Config example:

{
  channels: {
    mattermost: {
      replyToMode: "all",
    },
  },
}

Notes:

• Thread-scoped sessions use the triggering post id as the thread root.
• first and all are currently equivalent because once Mattermost has a thread root, follow-up chunks and media continue in that same thread.

Access control (DMs)

• Default: channels.mattermost.dmPolicy = "pairing" (unknown senders get a pairing code).
• Approve via:
• Public DMs: channels.mattermost.dmPolicy="open" plus channels.mattermost.allowFrom=["*"].

Channels (groups)

• Default: channels.mattermost.groupPolicy = "allowlist" (mention-gated).
• Allowlist senders with channels.mattermost.groupAllowFrom (user IDs recommended).
• @username matching is mutable and only enabled when channels.mattermost.dangerouslyAllowNameMatching: true.
• Open channels: channels.mattermost.groupPolicy="open" (mention-gated).
• Runtime note: if channels.mattermost is completely missing, runtime falls back to groupPolicy="allowlist" for group checks (even if channels.defaults.groupPolicy is set).

Targets for outbound delivery

Use these target formats with openclaw message send or cron/webhooks:

• channel:<id> for a channel
• user:<id> for a DM
• @username for a DM (resolved via the Mattermost API)

Bare opaque IDs (like 64ifufp...) are ambiguous in Mattermost (user ID vs channel ID).

OpenClaw resolves them user-first:

• If the ID exists as a user (GET /api/v4/users/<id> succeeds), OpenClaw sends a DM by resolving the direct channel via /api/v4/channels/direct.
• Otherwise the ID is treated as a channel ID.

If you need deterministic behavior, always use the explicit prefixes (user:<id> / channel:<id>).

DM channel retry

When OpenClaw sends to a Mattermost DM target and needs to resolve the direct channel first, it retries transient direct-channel creation failures by default.

Use channels.mattermost.dmChannelRetry to tune that behavior globally for the Mattermost plugin, or channels.mattermost.accounts.<id>.dmChannelRetry for one account.

{
  channels: {
    mattermost: {
      dmChannelRetry: {
        maxRetries: 3,
        initialDelayMs: 1000,
        maxDelayMs: 10000,
        timeoutMs: 30000,
      },
    },
  },
}

Notes:

• This applies only to DM channel creation (/api/v4/channels/direct), not every Mattermost API call.
• Retries apply to transient failures such as rate limits, 5xx responses, and network or timeout errors.
• 4xx client errors other than 429 are treated as permanent and are not retried.

Reactions (message tool)

• Use message action=react with channel=mattermost.
• messageId is the Mattermost post id.
• emoji accepts names like thumbsup or :+1: (colons are optional).
• Set remove=true (boolean) to remove a reaction.
• Reaction add/remove events are forwarded as system events to the routed agent session.

Examples:

message action=react channel=mattermost target=channel:<channelId> messageId=<postId> emoji=thumbsup
message action=react channel=mattermost target=channel:<channelId> messageId=<postId> emoji=thumbsup remove=true

Config:

• channels.mattermost.actions.reactions: enable/disable reaction actions (default true).
• Per-account override: channels.mattermost.accounts.<id>.actions.reactions.

Interactive buttons (message tool)

Send messages with clickable buttons. When a user clicks a button, the agent receives the selection and can respond.

Enable buttons by adding inlineButtons to the channel capabilities:

{
  channels: {
    mattermost: {
      capabilities: ["inlineButtons"],
    },
  },
}

Use message action=send with a buttons parameter. Buttons are a 2D array (rows of buttons):

message action=send channel=mattermost target=channel:<channelId> buttons=[[{"text":"Yes","callback_data":"yes"},{"text":"No","callback_data":"no"}]]

Button fields:

• text (required): display label.
• callback_data (required): value sent back on click (used as the action ID).
• style (optional): "default", "primary", or "danger".

When a user clicks a button:

1. All buttons are replaced with a confirmation line (e.g., "✓ Yes selected by @user").
2. The agent receives the selection as an inbound message and responds.

Notes:

• Button callbacks use HMAC-SHA256 verification (automatic, no config needed).
• Mattermost strips callback data from its API responses (security feature), so all buttons are removed on click — partial removal is not possible.
• Action IDs containing hyphens or underscores are sanitized automatically (Mattermost routing limitation).

Config:

• channels.mattermost.capabilities: array of capability strings. Add "inlineButtons" to enable the buttons tool description in the agent system prompt.
• channels.mattermost.interactions.callbackBaseUrl: optional external base URL for button callbacks (for example https://gateway.example.com). Use this when Mattermost cannot reach the gateway at its bind host directly.
• In multi-account setups, you can also set the same field under channels.mattermost.accounts.<id>.interactions.callbackBaseUrl.
• If interactions.callbackBaseUrl is omitted, OpenClaw derives the callback URL from gateway.customBindHost + gateway.port, then falls back to http://localhost:<port>.
• Reachability rule: the button callback URL must be reachable from the Mattermost server. localhost only works when Mattermost and OpenClaw run on the same host/network namespace.
• If your callback target is private/tailnet/internal, add its host/domain to Mattermost ServiceSettings.AllowedUntrustedInternalConnections.

Direct API integration (external scripts)

External scripts and webhooks can post buttons directly via the Mattermost REST API instead of going through the agent's message tool. Use buildButtonAttachments() from the extension when possible; if posting raw JSON, follow these rules:

Payload structure:

{
  channel_id: "<channelId>",
  message: "Choose an option:",
  props: {
    attachments: [
      {
        actions: [
          {
            id: "mybutton01", // alphanumeric only — see below
            type: "button", // required, or clicks are silently ignored
            name: "Approve", // display label
            style: "primary", // optional: "default", "primary", "danger"
            integration: {
              url: "https://gateway.example.com/mattermost/interactions/default",
              context: {
                action_id: "mybutton01", // must match button id (for name lookup)
                action: "approve",
                // ... any custom fields ...
                _token: "<hmac>", // see HMAC section below
              },
            },
          },
        ],
      },
    ],
  },
}

Critical rules:

1. Attachments go in props.attachments, not top-level attachments (silently ignored).
2. Every action needs type: "button" — without it, clicks are swallowed silently.
3. Every action needs an id field — Mattermost ignores actions without IDs.
4. Action id must be alphanumeric only ([a-zA-Z0-9]). Hyphens and underscores break Mattermost's server-side action routing (returns 404). Strip them before use.
5. context.action_id must match the button's id so the confirmation message shows the button name (e.g., "Approve") instead of a raw ID.
6. context.action_id is required — the interaction handler returns 400 without it.

HMAC token generation:

The gateway verifies button clicks with HMAC-SHA256. External scripts must generate tokens that match the gateway's verification logic:

1. Derive the secret from the bot token: HMAC-SHA256(key="openclaw-mattermost-interactions", data=botToken)
2. Build the context object with all fields except _token.
3. Serialize with sorted keys and no spaces (the gateway uses JSON.stringify with sorted keys, which produces compact output).
4. Sign: HMAC-SHA256(key=secret, data=serializedContext)
5. Add the resulting hex digest as _token in the context.

Python example:

import hmac, hashlib, json

secret = hmac.new(
    b"openclaw-mattermost-interactions",
    bot_token.encode(), hashlib.sha256
).hexdigest()

ctx = {"action_id": "mybutton01", "action": "approve"}
payload = json.dumps(ctx, sort_keys=True, separators=(",", ":"))
token = hmac.new(secret.encode(), payload.encode(), hashlib.sha256).hexdigest()

context = {**ctx, "_token": token}

Common HMAC pitfalls:

• Python's json.dumps adds spaces by default ({"key": "val"}). Use separators=(",", ":") to match JavaScript's compact output ({"key":"val"}).
• Always sign all context fields (minus _token). The gateway strips _token then signs everything remaining. Signing a subset causes silent verification failure.
• Use sort_keys=True — the gateway sorts keys before signing, and Mattermost may reorder context fields when storing the payload.
• Derive the secret from the bot token (deterministic), not random bytes. The secret must be the same across the process that creates buttons and the gateway that verifies.

Directory adapter

The Mattermost plugin includes a directory adapter that resolves channel and user names via the Mattermost API. This enables #channel-name and @username targets in openclaw message send and cron/webhook deliveries.

No configuration is needed — the adapter uses the bot token from the account config.

Multi-account

Mattermost supports multiple accounts under channels.mattermost.accounts:

{
  channels: {
    mattermost: {
      accounts: {
        default: { name: "Primary", botToken: "mm-token", baseUrl: "https://chat.example.com" },
        alerts: { name: "Alerts", botToken: "mm-token-2", baseUrl: "https://alerts.example.com" },
      },
    },
  },
}

Troubleshooting

• No replies in channels: ensure the bot is in the channel and mention it (oncall), use a trigger prefix (onchar), or set chatmode: "onmessage".
• Auth errors: check the bot token, base URL, and whether the account is enabled.
• Multi-account issues: env vars only apply to the default account.
• Buttons appear as white boxes: the agent may be sending malformed button data. Check that each button has both text and callback_data fields.
• Buttons render but clicks do nothing: verify AllowedUntrustedInternalConnections in Mattermost server config includes 127.0.0.1 localhost, and that EnablePostActionIntegration is true in ServiceSettings.
• Buttons return 404 on click: the button id likely contains hyphens or underscores. Mattermost's action router breaks on non-alphanumeric IDs. Use [a-zA-Z0-9] only.
• Gateway logs invalid _token: HMAC mismatch. Check that you sign all context fields (not a subset), use sorted keys, and use compact JSON (no spaces). See the HMAC section above.
• Gateway logs missing _token in context: the _token field is not in the button's context. Ensure it is included when building the integration payload.
• Confirmation shows raw ID instead of button name: context.action_id does not match the button's id. Set both to the same sanitized value.
• Agent doesn't know about buttons: add capabilities: ["inlineButtons"] to the Mattermost channel config.