Initial commit: OpenClaw Skill Collection

6 custom skills (assign-task, dispatch-webhook, daily-briefing,
task-capture, qmd-brain, tts-voice) with technical documentation.
Compatible with Claude Code, OpenClaw, Codex CLI, and OpenCode.

openclaw-knowhow-skill/docs/channels/mattermost.md

@@ -0,0 +1,64 @@
+# Mattermost Plugin
+
+## Overview
+
+OpenClaw integrates with Mattermost, a self-hostable team messaging platform, via a plugin.
+
+## Installation
+
+The plugin requires separate installation:
+
+```bash
+openclaw plugins install @openclaw/mattermost
+```
+
+## Core Configuration
+
+The minimal setup requires three elements:
+
+- A bot token
+- Base URL
+- A DM policy
+
+Mattermost responds to DMs automatically, with channel interactions governed by the `chatmode` setting.
+
+## Chat Modes
+
+Three response patterns are available:
+
+- **oncall** (default): responds only to @mentions
+- **onmessage**: replies to all channel messages
+- **onchar**: triggers on specific prefix characters like `>` or `!`
+
+## Access Controls
+
+### DM Security
+
+Uses a pairing code system by default, allowing administrators to approve unknown senders.
+
+### Channel Access
+
+Controlled via allowlists using the `groupAllowPolicy` setting.
+
+## Multi-Account Support
+
+Multiple Mattermost instances can be configured simultaneously under separate account identifiers, each with independent tokens and base URLs.
+
+## Message Delivery Targets
+
+Outbound messages use standardized formats:
+
+- `channel:<id>` - Channel messages
+- `user:<id>` - Direct messages by user ID
+- `@username` - Direct messages by username
+
+## Environment Variables
+
+Environment variable alternatives are available for the default account configuration.
+
+## Troubleshooting
+
+Common issues involve:
+
+- Channel visibility
+- Authentication issues