feat(channels): add Mattermost channel support

README.md

@@ -308,7 +308,7 @@ That's it! You have a working AI assistant in 2 minutes.
 
 ## 💬 Chat Apps
 
-Talk to your picoclaw through Telegram, Discord, WhatsApp, Matrix, QQ, DingTalk, LINE, or WeCom
+Talk to your picoclaw through Telegram, Discord, WhatsApp, Matrix, Mattermost, QQ, DingTalk, LINE, or WeCom
 
 > **Note**: All webhook-based channels (LINE, WeCom, etc.) are served on a single shared Gateway HTTP server (`gateway.host`:`gateway.port`, default `127.0.0.1:18790`). There are no per-channel ports to configure. Note: Feishu uses WebSocket/SDK mode and does not use the shared HTTP webhook server.
 
@@ -321,6 +321,7 @@ Talk to your picoclaw through Telegram, Discord, WhatsApp, Matrix, QQ, DingTalk,
 | **QQ**       | Easy (AppID + AppSecret)           |
 | **DingTalk** | Medium (app credentials)           |
 | **LINE**     | Medium (credentials + webhook URL) |
+| **Mattermost** | Easy (bot token)                   |
 | **WeCom AI Bot** | Medium (Token + AES key)       |
 
 <details>
@@ -436,6 +437,47 @@ picoclaw gateway
 
 </details>
 
+<details>
+<summary><b>Mattermost</b></summary>
+
+**1. Create a bot account**
+
+* Go to your Mattermost instance → Integrations → Bot Accounts → Add Bot Account
+* Copy the bot token
+
+**2. Configure**
+
+```json
+{
+  "channels": {
+    "mattermost": {
+      "enabled": true,
+      "url": "https://your-mattermost-server.com",
+      "token": "YOUR_BOT_TOKEN",
+      "username": "picoclaw",
+      "reply_in_thread": true,
+      "allow_from": ["YOUR_USER_ID"]
+    }
+  }
+}
+```
+
+| Field            | Type   | Required | Description                                     |
+| ---------------- | ------ | -------- | ----------------------------------------------- |
+| enabled          | bool   | Yes      | Enable Mattermost channel                       |
+| url              | string | Yes      | Mattermost server URL                           |
+| token            | string | Yes      | Bot access token                                |
+| username         | string | No       | Bot username for @mention stripping             |
+| reply_in_thread  | bool   | No       | Auto-thread replies in channels (default: true) |
+| allow_from       | array  | No       | User ID allowlist (empty = allow all)           |
+| group_trigger    | object | No       | Group trigger config (mention_only, etc.)       |
+| typing           | object | No       | Typing indicator config (enabled, etc.)         |
+| placeholder      | object | No       | Placeholder config (enabled, text; default: "Thinking... 💭") |
+
+**3. Add the bot to channels** in Mattermost, then DM it or @mention it.
+
+</details>
+
 <details>
 <summary><b>WhatsApp</b> (native via whatsmeow)</summary>
 

cmd/picoclaw/internal/gateway/helpers.go

@@ -20,6 +20,7 @@ import (
 	_ "github.com/sipeed/picoclaw/pkg/channels/line"
 	_ "github.com/sipeed/picoclaw/pkg/channels/maixcam"
 	_ "github.com/sipeed/picoclaw/pkg/channels/matrix"
+	_ "github.com/sipeed/picoclaw/pkg/channels/mattermost"
 	_ "github.com/sipeed/picoclaw/pkg/channels/onebot"
 	_ "github.com/sipeed/picoclaw/pkg/channels/pico"
 	_ "github.com/sipeed/picoclaw/pkg/channels/qq"

docs/channels/mattermost/README.zh.md

@@ -0,0 +1,50 @@
+# Mattermost
+
+Mattermost 是一个开源的团队协作平台。PicoClaw 通过 WebSocket API v4 和 REST API v4 连接到 Mattermost 服务器，支持接收和发送消息、文件上传、线程回复和输入指示器。
+
+## 配置
+
+```json
+{
+  "channels": {
+    "mattermost": {
+      "enabled": true,
+      "url": "https://your-mattermost-server.com",
+      "token": "YOUR_BOT_TOKEN",
+      "username": "picoclaw",
+      "reply_in_thread": true,
+      "allow_from": ["YOUR_USER_ID"]
+    }
+  }
+}
+```
+
+| 字段             | 类型   | 必填 | 描述                                     |
+| ---------------- | ------ | ---- | ---------------------------------------- |
+| enabled          | bool   | 是   | 是否启用 Mattermost 频道                 |
+| url              | string | 是   | Mattermost 服务器地址                    |
+| token            | string | 是   | 机器人访问令牌                           |
+| username         | string | 否   | 机器人用户名（用于去除 @提及）           |
+| reply_in_thread  | bool   | 否   | 在频道中自动使用线程回复（默认：true）   |
+| allow_from       | array  | 否   | 用户ID白名单，空表示允许所有用户         |
+| group_trigger    | object | 否   | 群组触发设置                             |
+| typing           | object | 否   | 输入指示器设置                           |
+| placeholder      | object | 否   | 占位消息设置（默认启用，文本："Thinking... 💭"）|
+
+## 设置流程
+
+1. 前往 Mattermost 管理后台 → 集成 → 机器人帐户 → 添加机器人帐户
+2. 复制机器人令牌
+3. 将令牌填入配置文件中
+4. 将机器人添加到需要的频道
+5. 通过私信或 @提及 与机器人交互
+
+## 功能
+
+- **线程回复**：频道消息自动使用线程，私信保持平面结构
+- **自动重连**：WebSocket 断开后自动重连（指数退避 5s-60s）
+- **消息分割**：超长消息自动分割（上限 4000 字符）
+- **文件上传**：支持通过 MediaSender 接口上传文件
+- **输入指示器**：支持显示"正在输入"状态
+- **消息编辑**：支持编辑已发送的消息
+- **占位消息**：发送"思考中..."占位消息，完成后替换为实际回复

pkg/channels/manager.go

@@ -252,6 +252,12 @@ func (m *Manager) initChannels() error {
 		m.initChannel("matrix", "Matrix")
 	}
 
+	if m.config.Channels.Mattermost.Enabled &&
+		m.config.Channels.Mattermost.Token != "" &&
+		m.config.Channels.Mattermost.URL != "" {
+		m.initChannel("mattermost", "Mattermost")
+	}
+
 	if m.config.Channels.LINE.Enabled && m.config.Channels.LINE.ChannelAccessToken != "" {
 		m.initChannel("line", "LINE")
 	}

pkg/channels/mattermost/init.go

@@ -0,0 +1,13 @@
+package mattermost
+
+import (
+	"github.com/sipeed/picoclaw/pkg/bus"
+	"github.com/sipeed/picoclaw/pkg/channels"
+	"github.com/sipeed/picoclaw/pkg/config"
+)
+
+func init() {
+	channels.RegisterFactory("mattermost", func(cfg *config.Config, b *bus.MessageBus) (channels.Channel, error) {
+		return NewMattermostChannel(cfg.Channels.Mattermost, b)
+	})
+}