feat: v4.3 生态扩展 — 诊断系统 + Heartbeat + 子代理 + MCP

新增功能：

1. 🩺 一键诊断系统
   - 设置面板添加「一键诊断」按钮
   - 检查项：Ollama 连接、模型可用性、模型能力（Tools/Vision/Think）、
     SQLite 数据库、技能系统、应用版本信息
   - 实时渲染诊断结果，✅/⚠️/❌ 状态标识

2. 💓 Heartbeat 后台检查
   - 设置面板添加开关 + 间隔选择（10分/30分/1小时/2小时）
   - 定时检查 Ollama 连接，异常时系统通知
   - 配置持久化到 settings，启动时自动恢复
   - startHeartbeat/stopHeartbeat/restoreHeartbeat 三件套

3. 🤖 子代理委派（spawn_task）
   - 新增 spawn_task 工具（26 个工具）
   - 子 Agent 独立运行（独立消息上下文，5 轮上限，2 分钟超时）
   - 不支持工具调用，专注于文本推理任务
   - 主 Agent 可传入附加上下文
   - 结果返回主 Agent Loop

4. 🔌 MCP Client 框架
   - mcp-client.ts: MCP 服务器配置管理（增删改查、启用禁用）
   - 配置存储在 settings.mcp_servers
   - 工具注册框架就绪，待主进程 MCP bridge 实现协议通信

新增文件：mcp-client.ts, sub-agent.ts
修改文件：settings-modal.ts, index.html, main.ts, tool-registry.ts

src/renderer/components/settings-modal.ts

@@ -117,6 +117,40 @@ export function initSettingsModal(): void {
     });
   });
 
+  // ── v4.3 诊断系统 ──
+  document.querySelector('#btnDoctor')!.addEventListener('click', runDoctor);
+
+  // ── v4.3 Heartbeat 后台检查 ──
+  const toggleHB = document.querySelector<HTMLInputElement>('#toggleHeartbeat')!;
+  const selectHBInterval = document.querySelector<HTMLSelectElement>('#selectHeartbeatInterval')!;
+
+  toggleHB.addEventListener('change', async () => {
+    const enabled = toggleHB.checked;
+    state.set('heartbeatEnabled', enabled);
+    const db = state.get<ChatDB | null>(KEYS.DB);
+    if (db) await db.saveSetting('heartbeatEnabled', enabled);
+    if (enabled) {
+      startHeartbeat(parseInt(selectHBInterval.value));
+      showToast('后台检查已启用', 'success');
+    } else {
+      stopHeartbeat();
+      showToast('后台检查已关闭', 'info');
+    }
+    logSetting('后台检查', enabled ? '已启用' : '已关闭');
+  });
+
+  selectHBInterval.addEventListener('change', async () => {
+    const ms = parseInt(selectHBInterval.value);
+    state.set('heartbeatInterval', ms);
+    const db = state.get<ChatDB | null>(KEYS.DB);
+    if (db) await db.saveSetting('heartbeatInterval', ms);
+    if (state.get<boolean>('heartbeatEnabled', false)) {
+      stopHeartbeat();
+      startHeartbeat(ms);
+    }
+    logSetting('检查间隔', `${ms / 60000} 分钟`);
+  });
+
   document.querySelector('#btnReleaseVRAM')!.addEventListener('click', async () => {
     const api = state.get<OllamaAPI>(KEYS.API);
     const model = (document.querySelector('#modelSelect') as HTMLSelectElement).value;
@@ -402,3 +436,149 @@ async function importSessions(filePath: string): Promise<void> {
     logError('导入失败', (err as Error).message);
   }
 }
+
+// ══════════════════════════════════════════════
+// v4.3 诊断系统
+// ══════════════════════════════════════════════
+
+async function runDoctor(): Promise<void> {
+  const resultsEl = document.querySelector('#doctorResults')!;
+  resultsEl.style.display = '';
+  resultsEl.innerHTML = '<div>🩺 正在诊断...</div>';
+
+  const checks: Array<{ name: string; status: 'ok' | 'warn' | 'error'; detail: string }> = [];
+
+  // 1. Ollama 连接
+  const api = state.get<OllamaAPI>(KEYS.API);
+  try {
+    const version = await api!.getVersion();
+    checks.push({ name: 'Ollama 连接', status: 'ok', detail: `v${version.version}` });
+  } catch (err) {
+    checks.push({ name: 'Ollama 连接', status: 'error', detail: `无法连接: ${(err as Error).message}` });
+  }
+
+  // 2. 模型可用性
+  try {
+    const models = await api!.listModels();
+    const count = models.models?.length || 0;
+    checks.push({ name: '已安装模型', status: count > 0 ? 'ok' : 'warn', detail: `${count} 个模型` });
+  } catch {
+    checks.push({ name: '已安装模型', status: 'error', detail: '无法获取模型列表' });
+  }
+
+  // 3. 当前模型能力
+  const model = (document.querySelector('#modelSelect') as HTMLSelectElement)?.value;
+  if (model) {
+    try {
+      const detail = await api!.showModel(model);
+      const caps = detail.capabilities || [];
+      const hasTools = caps.includes('tools');
+      const hasVision = caps.includes('vision');
+      const hasThink = caps.includes('thinking');
+      checks.push({
+        name: `模型能力 (${model})`,
+        status: hasTools ? 'ok' : 'warn',
+        detail: `Tool Calling: ${hasTools ? '✅' : '❌'} | Vision: ${hasVision ? '✅' : '❌'} | Think: ${hasThink ? '✅' : '❌'}`
+      });
+    } catch {
+      checks.push({ name: '模型能力', status: 'warn', detail: '无法检测模型能力' });
+    }
+  } else {
+    checks.push({ name: '当前模型', status: 'warn', detail: '未选择模型' });
+  }
+
+  // 4. SQLite 数据库
+  const db = state.get<ChatDB | null>(KEYS.DB);
+  if (db) {
+    try {
+      const sessions = await db.getAllSessions();
+      checks.push({ name: 'SQLite 数据库', status: 'ok', detail: `${sessions.length} 个会话` });
+    } catch (err) {
+      checks.push({ name: 'SQLite 数据库', status: 'error', detail: `错误: ${(err as Error).message}` });
+    }
+  } else {
+    checks.push({ name: 'SQLite 数据库', status: 'error', detail: '未初始化' });
+  }
+
+  // 5. 技能系统
+  try {
+    if (db && (db as any).getAllSkills) {
+      const skills = await (db as any).getAllSkills();
+      checks.push({ name: '技能系统', status: 'ok', detail: `${skills.length} 个技能` });
+    } else {
+      checks.push({ name: '技能系统', status: 'ok', detail: '已就绪' });
+    }
+  } catch {
+    checks.push({ name: '技能系统', status: 'warn', detail: '无法获取技能列表' });
+  }
+
+  // 6. 版本信息
+  const bridge = (window as any).metonaDesktop;
+  if (bridge?.info) {
+    try {
+      const info = await bridge.info();
+      checks.push({ name: '应用信息', status: 'ok', detail: `v${info.version} | Electron ${info.electronVersion} | ${info.platform} ${info.arch}` });
+    } catch {
+      checks.push({ name: '应用信息', status: 'warn', detail: '无法获取' });
+    }
+  }
+
+  // 渲染结果
+  const statusIcon = (s: string) => s === 'ok' ? '✅' : s === 'warn' ? '⚠️' : '❌';
+  const allOk = checks.every(c => c.status === 'ok');
+
+  resultsEl.innerHTML = `
+    <div style="margin-bottom:6px;font-weight:600;">${allOk ? '✅ 所有检查通过' : '⚠️ 发现问题'}</div>
+    ${checks.map(c => `<div style="margin:4px 0;">${statusIcon(c.status)} <strong>${c.name}</strong>: ${c.detail}</div>`).join('')}
+  `;
+
+  logInfo('系统诊断完成', `${checks.filter(c => c.status === 'ok').length}/${checks.length} 项通过`);
+}
+
+// ══════════════════════════════════════════════
+// v4.3 Heartbeat 后台检查
+// ══════════════════════════════════════════════
+
+let heartbeatTimer: ReturnType<typeof setInterval> | null = null;
+
+export function startHeartbeat(intervalMs: number): void {
+  stopHeartbeat();
+  heartbeatTimer = setInterval(async () => {
+    const api = state.get<OllamaAPI>(KEYS.API);
+    if (!api) return;
+
+    try {
+      await api.getVersion();
+      // 连接正常，静默
+    } catch {
+      // 连接异常，通知用户
+      const bridge = (window as any).metonaDesktop;
+      if (bridge?.notify) {
+        bridge.notify('Metona Ollama', '⚠️ Ollama 服务连接异常，请检查是否正在运行');
+      }
+      logWarn('Heartbeat: Ollama 连接异常');
+    }
+  }, intervalMs);
+  logInfo(`Heartbeat 已启动`, `间隔: ${intervalMs / 60000} 分钟`);
+}
+
+export function stopHeartbeat(): void {
+  if (heartbeatTimer) {
+    clearInterval(heartbeatTimer);
+    heartbeatTimer = null;
+  }
+}
+
+/** 应用启动时恢复 heartbeat */
+export function restoreHeartbeat(): void {
+  const enabled = state.get<boolean>('heartbeatEnabled', false);
+  const interval = state.get<number>('heartbeatInterval', 3600000);
+  if (enabled) {
+    startHeartbeat(interval);
+    // 同步 UI 状态
+    const toggle = document.querySelector<HTMLInputElement>('#toggleHeartbeat');
+    if (toggle) toggle.checked = true;
+    const select = document.querySelector<HTMLSelectElement>('#selectHeartbeatInterval');
+    if (select) select.value = String(interval);
+  }
+}

src/renderer/index.html

@@ -322,6 +322,31 @@
                 </div>
                 <p class="text-muted" style="margin-top:6px;font-size:11px;">导出格式为 JSON，可备份后在其他设备导入恢复。</p>
             </div>
+            <div class="setting-group">
+                <label class="setting-label">💓 后台检查（Heartbeat）</label>
+                <div style="display:flex;align-items:center;gap:10px;">
+                    <label class="toggle-label" style="margin:0;">
+                        <input type="checkbox" id="toggleHeartbeat">
+                        <span class="toggle-slider"></span>
+                    </label>
+                    <span style="font-size:13px;">启用后台定时检查</span>
+                </div>
+                <div style="display:flex;gap:8px;align-items:center;margin-top:8px;">
+                    <label style="font-size:12px;color:var(--text-muted);">检查间隔</label>
+                    <select id="selectHeartbeatInterval" class="setting-input" style="width:auto;margin-bottom:0;padding:4px 8px;">
+                        <option value="600000">10 分钟</option>
+                        <option value="1800000">30 分钟</option>
+                        <option value="3600000" selected>1 小时</option>
+                        <option value="7200000">2 小时</option>
+                    </select>
+                </div>
+                <p class="text-muted" style="margin-top:4px;font-size:11px;">定期检查 Ollama 连接状态和模型可用性，异常时通过系统通知提醒。</p>
+            </div>
+            <div class="setting-group">
+                <label class="setting-label">🩺 系统诊断</label>
+                <button class="btn btn-outline" id="btnDoctor" style="margin-bottom:8px;">🩺 一键诊断</button>
+                <div id="doctorResults" style="display:none;margin-top:8px;padding:10px;background:var(--bg-layer);border-radius:var(--radius-control);font-size:12px;max-height:200px;overflow-y:auto;"></div>
+            </div>
         </div>
     </div>
 </div>

src/renderer/main.ts

@@ -22,6 +22,7 @@ import { initHistoryModal, closeHistoryModal } from './components/history-modal.
 import { initMemoryModal } from './components/memory-modal.js';
 import { initToolsModal, closeToolsModal } from './components/tools-modal.js';
 import { initMemoryManager } from './services/memory-manager.js';
+import { restoreHeartbeat } from './components/settings-modal.js';
 import { setToolEnabled, setRunCommandMode } from './services/tool-registry.js';
 import { initToolConfirmModal } from './components/tool-confirm-modal.js';
 import { initWorkspacePanel } from './components/workspace-panel.js';
@@ -378,10 +379,19 @@ async function init(): Promise<void> {
       }
     });
 
+    // ── v4.3 Heartbeat 恢复 ──
+    const heartbeatEnabled = await db.getSetting('heartbeatEnabled', false);
+    const heartbeatInterval = await db.getSetting('heartbeatInterval', 3600000);
+    state.set('heartbeatEnabled', heartbeatEnabled);
+    state.set('heartbeatInterval', heartbeatInterval);
+
     (document.querySelector('#chatInput') as HTMLElement)?.focus();
     updateTotalTokens();
 
     logSuccess('应用初始化完成');
+
+    // Heartbeat 在 UI 就绪后启动
+    restoreHeartbeat();
   } catch (err) {
     logError('初始化失败', (err as Error).message);
     if (!api!) {

src/renderer/services/mcp-client.ts

@@ -0,0 +1,90 @@
+/**
+ * MCP Client - Model Context Protocol 客户端 (v4.3)
+ * 轻量级实现：管理 MCP Server 配置，提供工具注册框架
+ *
+ * MCP Server 配置存储在 settings.mcp_servers 中，格式：
+ * [
+ *   { "name": "filesystem", "command": "npx", "args": ["-y", "@anthropic/mcp-filesystem"], "enabled": true },
+ *   { "name": "sqlite", "command": "npx", "args": ["-y", "@anthropic/mcp-sqlite", "./data.db"], "enabled": false }
+ * ]
+ */
+
+import { state, KEYS } from '../state/state.js';
+import { logInfo, logWarn } from './log-service.js';
+import type { ToolDefinition } from '../types.js';
+
+export interface MCPServerConfig {
+  name: string;
+  command: string;
+  args: string[];
+  enabled: boolean;
+  description?: string;
+}
+
+/** 获取所有 MCP 服务器配置 */
+export async function getMCPServers(): Promise<MCPServerConfig[]> {
+  const db = state.get<any>(KEYS.DB);
+  if (!db) return [];
+  try {
+    return await db.getSetting('mcp_servers', []);
+  } catch {
+    return [];
+  }
+}
+
+/** 保存 MCP 服务器配置 */
+export async function saveMCPServers(servers: MCPServerConfig[]): Promise<void> {
+  const db = state.get<any>(KEYS.DB);
+  if (db) await db.saveSetting('mcp_servers', servers);
+}
+
+/** 添加 MCP 服务器 */
+export async function addMCPServer(config: MCPServerConfig): Promise<void> {
+  const servers = await getMCPServers();
+  const existing = servers.findIndex(s => s.name === config.name);
+  if (existing >= 0) {
+    servers[existing] = config;
+  } else {
+    servers.push(config);
+  }
+  await saveMCPServers(servers);
+  logInfo(`MCP Server 已${existing >= 0 ? '更新' : '添加'}: ${config.name}`);
+}
+
+/** 删除 MCP 服务器 */
+export async function removeMCPServer(name: string): Promise<void> {
+  const servers = await getMCPServers();
+  await saveMCPServers(servers.filter(s => s.name !== name));
+  logInfo(`MCP Server 已删除: ${name}`);
+}
+
+/** 切换 MCP 服务器启用状态 */
+export async function toggleMCPServer(name: string): Promise<boolean> {
+  const servers = await getMCPServers();
+  const server = servers.find(s => s.name === name);
+  if (!server) return false;
+  server.enabled = !server.enabled;
+  await saveMCPServers(servers);
+  logInfo(`MCP Server ${server.enabled ? '已启用' : '已禁用'}: ${name}`);
+  return server.enabled;
+}
+
+/** 获取已启用的 MCP 服务器 */
+export async function getEnabledMCPServers(): Promise<MCPServerConfig[]> {
+  const servers = await getMCPServers();
+  return servers.filter(s => s.enabled);
+}
+
+/**
+ * 获取 MCP 工具定义（供 Agent 使用）
+ * 目前返回占位工具定义，实际 MCP 协议通信需通过主进程实现
+ */
+export async function getMCPToolDefinitions(): Promise<ToolDefinition[]> {
+  const enabled = await getEnabledMCPServers();
+  // MCP 工具通过主进程的 MCP bridge 动态注册
+  // 这里返回空数组，工具定义由 MCP bridge 在 IPC 层注入
+  if (enabled.length > 0) {
+    logInfo(`MCP: ${enabled.length} 个服务器已启用`, enabled.map(s => s.name).join(', '));
+  }
+  return [];
+}

src/renderer/services/sub-agent.ts

@@ -0,0 +1,112 @@
+/**
+ * SubAgent - 子代理委派系统 (v4.3)
+ * 允许主 Agent 将独立任务委派给子 Agent 执行
+ * 子 Agent 独立运行，完成后将结果返回给主 Agent
+ */
+
+import { state, KEYS } from '../state/state.js';
+import { OllamaAPI } from '../api/ollama.js';
+import { logInfo, logWarn, logError, logAgentLoop } from './log-service.js';
+import type { ToolResult } from '../types.js';
+
+const SUB_AGENT_TIMEOUT = 120000; // 2 分钟超时
+const SUB_AGENT_MAX_LOOPS = 5;    // 子 Agent 最多 5 轮
+
+/**
+ * 执行子 Agent 任务
+ * @param task 子任务描述
+ * @param context 附加上下文（主 Agent 提供的参考信息）
+ * @returns 子 Agent 的执行结果
+ */
+export async function executeSubAgent(task: string, context?: string): Promise<ToolResult> {
+  const api = state.get<OllamaAPI>(KEYS.API);
+  const model = state.get<string>('_defaultModel', '');
+
+  if (!api || !model) {
+    return { success: false, error: '未选择模型，无法执行子任务' };
+  }
+
+  logInfo(`子 Agent 启动`, `任务: ${task.slice(0, 80)}`);
+
+  const systemPrompt = `你是一个子任务执行 Agent。你的任务是高效完成指定的单一任务，然后给出简洁的结果报告。
+不要闲聊，不要说废话。直接执行任务，完成后给出结果。
+${context ? `\n附加上下文：\n${context}` : ''}`;
+
+  const messages: Array<{ role: string; content: string }> = [
+    { role: 'system', content: systemPrompt },
+    { role: 'user', content: task }
+  ];
+
+  let resultContent = '';
+  let loopCount = 0;
+  const startTime = Date.now();
+
+  try {
+    while (loopCount < SUB_AGENT_MAX_LOOPS) {
+      loopCount++;
+
+      if (Date.now() - startTime > SUB_AGENT_TIMEOUT) {
+        logWarn('子 Agent 超时', `${loopCount} 轮`);
+        break;
+      }
+
+      let content = '';
+      let toolCalls: Array<{ name: string; arguments: Record<string, unknown> }> = [];
+
+      await api.chatStream({
+        model,
+        messages,
+        stream: true,
+        think: false,
+        options: { num_ctx: 8192, temperature: 0.3 }
+      } as any, (chunk: any) => {
+        if (chunk.message?.content) content += chunk.message.content;
+        if (chunk.message?.tool_calls?.length) {
+          for (const tc of chunk.message.tool_calls) {
+            if (tc.function?.name) {
+              toolCalls.push({ name: tc.function.name, arguments: tc.function.arguments || {} });
+            }
+          }
+        }
+      });
+
+      resultContent = content;
+
+      if (toolCalls.length === 0) {
+        // 子 Agent 完成
+        logInfo(`子 Agent 完成`, `${loopCount} 轮, ${resultContent.length} 字`);
+        return {
+          success: true,
+          content: resultContent,
+          loops: loopCount,
+          duration: Date.now() - startTime
+        };
+      }
+
+      // 子 Agent 调用了工具（不支持，提示直接回答）
+      messages.push({ role: 'assistant', content });
+      messages.push({
+        role: 'user',
+        content: '你无法调用工具。请基于已有信息直接给出回答。如果需要工具才能完成，请说明你无法完成此任务及原因。'
+      });
+    }
+
+    // 达到最大轮次
+    logWarn('子 Agent 达到最大轮次', `${loopCount} 轮`);
+    return {
+      success: true,
+      content: resultContent || '（子任务执行超时）',
+      loops: loopCount,
+      duration: Date.now() - startTime,
+      partial: true
+    };
+  } catch (err) {
+    logError('子 Agent 错误', (err as Error).message);
+    return {
+      success: false,
+      error: (err as Error).message,
+      loops: loopCount,
+      duration: Date.now() - startTime
+    };
+  }
+}

src/renderer/services/tool-registry.ts

@@ -415,6 +415,24 @@ export const TOOL_DEFINITIONS: ToolDefinition[] = [
         }
       }
     }
+  },
+  // ══════════════════════════════════════════════
+  // v4.3 新增工具：子代理委派
+  // ══════════════════════════════════════════════
+  {
+    type: 'function',
+    function: {
+      name: 'spawn_task',
+      description: 'Spawn a sub-agent to independently execute a task. The sub-agent runs in isolation without tool access and returns a result. Use this to parallelize independent sub-tasks or delegate focused work.',
+      parameters: {
+        type: 'object',
+        required: ['task'],
+        properties: {
+          task: { type: 'string', description: 'The task description for the sub-agent to execute.' },
+          context: { type: 'string', description: 'Optional additional context or reference data for the sub-agent.' }
+        }
+      }
+    }
   }
 ];
 
@@ -446,7 +464,7 @@ let enabledTools: Set<string> = new Set([
   'move_file', 'copy_file', 'web_fetch', 'web_search', 'append_file', 'edit_file',
   'get_file_info', 'tree', 'download_file', 'diff_files', 'replace_in_files',
   'read_multiple_files', 'git', 'compress',
-  'memory_search', 'memory_add', 'session_list', 'session_read'
+  'memory_search', 'memory_add', 'session_list', 'session_read', 'spawn_task'
 ]);
 
 export function setToolEnabled(toolName: string, enabled: boolean): void {
@@ -539,6 +557,18 @@ export async function executeTool(toolName: string, args: Record<string, unknown
       return { success: true, session: { id: session.id, title: session.title, model: session.model }, messages: msgs, total: messages.length };
     }
 
+    // v4.3 spawn_task 走子代理
+    if (toolName === 'spawn_task') {
+      const { executeSubAgent } = await import('./sub-agent.js');
+      const task = args.task as string;
+      const context = args.context as string | undefined;
+      if (!task) return { success: false, error: '缺少 task 参数' };
+      logInfo(`子代理委派: ${task.slice(0, 80)}`);
+      const result = await executeSubAgent(task, context);
+      logToolResult('spawn_task', result.success, result.success ? `完成, ${(result as any).loops} 轮` : result.error);
+      return result;
+    }
+
     // run_command 走 workspace IPC
     if (toolName === 'run_command') {
       const command = args.command as string;
@@ -581,7 +611,7 @@ export function getToolIcon(name: string): string {
     edit_file: '✂️', get_file_info: 'ℹ️', tree: '🌳', download_file: '⬇️',
     diff_files: '🔀', replace_in_files: '🔄', read_multiple_files: '📚',
     git: '🔖', compress: '🗜️', web_search: '🔍',
-    memory_search: '🧠', memory_add: '💾', session_list: '📋', session_read: '📖'
+    memory_search: '🧠', memory_add: '💾', session_list: '📋', session_read: '📖', spawn_task: '🤖'
   };
   return icons[name] || '🔧';
 }
@@ -595,7 +625,7 @@ export function formatToolName(name: string): string {
     get_file_info: '文件信息', tree: '目录树', download_file: '下载文件',
     diff_files: '文件对比', replace_in_files: '批量替换', read_multiple_files: '批量读取',
     git: 'Git 操作', compress: '压缩/解压', web_search: '联网搜索',
-    memory_search: '搜索记忆', memory_add: '添加记忆', session_list: '会话列表', session_read: '读取会话'
+    memory_search: '搜索记忆', memory_add: '添加记忆', session_list: '会话列表', session_read: '读取会话', spawn_task: '子代理委派'
   };
   return names[name] || name;
 }