feat(fsapp): add /llm command support for model switching

- Add /llm command to list available models
- Add /llm [n] command to switch to specific model
- Improve /status command to show current LLM info with emoji indicators
- Update /help text to include /llm command
- Unify command parsing logic using parts and op variables

This brings fsapp.py (Feishu/Lark) frontend in line with other chat frontends (QQ, DingTalk, WeCom) that already support all slash commands.

frontends/fsapp.py

@@ -588,18 +588,32 @@ def handle_command(open_id, cmd, chat_id=None):
             send_message(chat_id, content, receive_id_type="chat_id")
         else:
             send_message(open_id, content)
-    if cmd == "/stop":
+    parts = (cmd or "").split()
+    op = (parts[0] if parts else "").lower()
+    if op == "/stop":
         if open_id in user_tasks:
             user_tasks[open_id]["running"] = False
         agent.abort()
         _send_cmd_response("正在停止...")
-    elif cmd == "/new":
+    elif op == "/new":
         _send_cmd_response(reset_conversation(agent))
-    elif cmd == "/help":
-        _send_cmd_response("命令列表:\n/stop - 停止当前任务\n/status - 查看状态\n/restore - 恢复上次对话历史\n/continue - 列出可恢复会话\n/continue [n] - 恢复第 n 个会话\n/new - 开启新对话并清空当前上下文\n/help - 显示帮助")
-    elif cmd == "/status":
-        _send_cmd_response(f"状态: {'空闲' if not agent.is_running else '运行中'}")
-    elif cmd == "/restore":
+    elif op == "/help":
+        _send_cmd_response("命令列表:\n/stop - 停止当前任务\n/status - 查看状态\n/llm - 查看当前模型列表\n/llm [n] - 切换到第 n 个模型\n/restore - 恢复上次对话历史\n/continue - 列出可恢复会话\n/continue [n] - 恢复第 n 个会话\n/new - 开启新对话并清空当前上下文\n/help - 显示帮助")
+    elif op == "/status":
+        llm = agent.get_llm_name() if agent.llmclient else "未配置"
+        _send_cmd_response(f"状态: {'🔴 运行中' if agent.is_running else '🟢 空闲'}\nLLM: [{agent.llm_no}] {llm}")
+    elif op == "/llm":
+        if not agent.llmclient:
+            return _send_cmd_response("❌ 当前没有可用的 LLM 配置")
+        if len(parts) > 1:
+            try:
+                agent.next_llm(int(parts[1]))
+                return _send_cmd_response(f"✅ 已切换到 [{agent.llm_no}] {agent.get_llm_name()}")
+            except Exception:
+                return _send_cmd_response(f"用法: /llm <0-{len(agent.list_llms()) - 1}>")
+        lines = [f"{'→' if cur else '  '} [{i}] {name}" for i, name, cur in agent.list_llms()]
+        _send_cmd_response("LLMs:\n" + "\n".join(lines))
+    elif op == "/restore":
         try:
             restored_info, err = format_restore()
             if err:
@@ -610,7 +624,7 @@ def handle_command(open_id, cmd, chat_id=None):
             _send_cmd_response(f"已恢复 {count} 轮对话\n来源: {fname}\n(仅恢复上下文，请输入新问题继续)")
         except Exception as e:
             _send_cmd_response(f"恢复失败: {e}")
-    elif cmd.startswith("/continue"):
+    elif op == "/continue" or cmd.startswith("/continue"):
         _send_cmd_response(handle_continue_frontend(agent, cmd))
     else:
         _send_cmd_response(f"未知命令: {cmd}")