feat: 公共 API 基座化（v0.12.0，纯增量）— 类型/能力/设置 seam 全面补齐

- 类型生态：service 模块 re-export SidebarTab/SidebarState/SidebarStore/
  SidebarSnapshot/SidebarDiffRef/TabType/SessionScope/SidebarPrefs 等公共
  状态词汇（此前 TS2459 无法命名）；context-types 去 Node 依赖（结构镜像
  SidebarHttpRequest/Response/UpgradeSocket/Head），client 可达声明图零
  node:* 引用，外部消费者无 @types/node + skipLibCheck:false 可编译
  （scripts/check-consumer-types.sh 守护）
- 服务能力：version/features 版本与能力探测（单调只增）、getSnapshot/
  subscribeState 状态订阅、updateTab（title/path/meta）、activateTab、
  openFile（路径派生 id 与内置拦截一致）、openTab(seed, scope?) 定向到
  指定 session（store.reduceFor 不扰动 UI）
- TabDescriptor：badge 角标（99+ 封顶，抛错吞掉）、onOpen/onActivate/
  onClose 生命周期回调（service 路径派发，dedupe 聚焦触发 onActivate
  而非 onOpen，抛错不打断流程）；SidebarTab.meta JSON 可序列化跨刷新
  持久化（sanitize 宽松保留）
- 设置 seam 开放：PrefsSchema 增 pluginSettings 开放嵌套 map（z.dict），
  settings.pluginToggles（插件自有行，同 switch/text/number 控件）与
  settings.render（自定义面板，含 store/service/prefs/updatePluginSetting/
  close props）；viewer 卡片 v0.12.0 起也有齿轮设置弹窗
- FileViewerDescriptor.load 增第三参 AbortSignal（EditorHost 生命周期中止）
- UI 接线：tab 激活/关闭改走 service（跨树激活修复 + 回调触发）、+ 菜单
  传 scope、TabBar badge pill 渲染；active-session scope 走原 reduce 路径
  保证 notify
- 测试 +23：生命周期/定向打开/updateTab/activateTab/openFile/meta 持久化/
  reduceFor/能力常量（与 package.json 锁步）、consumer-types.ts 编译门、
  api-surface.spec.ts（client 图零 node 依赖守护）；既有 430 测试全绿
- 文档：AGENTS.md 修 available 三参示例并补全部新 API；external-plugin-
  guide.md 刷新至 v0.12.0（7 tab + 9 viewer、设置 seam 开放、类型导入
  路径建议）；README×2 服务化小节同步

未发版 npm（用户决定）；分支 feat/plugin-api-v012。

src/index.ts

@@ -15,8 +15,9 @@
 import { mkdir, open, readFile, rename, rm, stat, writeFile } from 'node:fs/promises'
 import { basename, dirname, extname, isAbsolute, join } from 'node:path'
 import type { IncomingMessage } from 'node:http'
+import type { Duplex } from 'node:stream'
 import { WebSocket, WebSocketServer } from 'ws'
-import type { Context } from './context-types.ts'
+import type { Context, SidebarHttpRequest } from './context-types.ts'
 import {
   Config,
   PrefsSchema,
@@ -436,7 +437,7 @@ export function apply(ctx: Context, config?: SidebarConfig): void {
   ensureSpawnHelper()
   const resolved = resolveSidebarConfig(config)
   const trustedHosts = trustedHostsOf(ctx)
-  const fence = (req: IncomingMessage): boolean => isTrustedApiRequest(req, trustedHosts)
+  const fence = (req: SidebarHttpRequest): boolean => isTrustedApiRequest(req, trustedHosts)
   const ptyManager = new PtyManager(defaultShell(), resolved.terminalsPerSession)
   // The agent-owned terminal registry: parallel to the UI-tab ptyManager,
   // keyed by uuid (the model's opaque handle) instead of `${sessionId}:${tabId}`,
@@ -669,7 +670,9 @@ export function apply(ctx: Context, config?: SidebarConfig): void {
         socket.destroy()
         return
       }
-      wss.handleUpgrade(req, socket, head, (ws) => {
+      // The structural request/socket/head faces satisfy the shared fence;
+      // the `ws` package wants the real Node types — cast at this boundary.
+      wss.handleUpgrade(req as unknown as IncomingMessage, socket as unknown as Duplex, head as Buffer, (ws) => {
         void attachTerminal(ctx, ptyManager, agentPtyRegistry, ws, req, resolved)
       })
     },
@@ -691,7 +694,7 @@ export function apply(ctx: Context, config?: SidebarConfig): void {
         socket.destroy()
         return
       }
-      agentListWss.handleUpgrade(req, socket, head, (ws) => {
+      agentListWss.handleUpgrade(req as unknown as IncomingMessage, socket as unknown as Duplex, head as Buffer, (ws) => {
         void attachAgentList(agentPtyRegistry, ws, req)
       })
     },
@@ -710,7 +713,7 @@ export function apply(ctx: Context, config?: SidebarConfig): void {
 async function attachAgentList(
   registry: AgentPtyRegistry,
   ws: WebSocket,
-  req: IncomingMessage,
+  req: SidebarHttpRequest,
 ): Promise<void> {
   try {
     const url = new URL(req.url ?? '/', 'http://dsh.internal')
@@ -750,7 +753,7 @@ async function attachTerminal(
   ptyManager: PtyManager,
   agentPtyRegistry: AgentPtyRegistry,
   ws: WebSocket,
-  req: IncomingMessage,
+  req: SidebarHttpRequest,
   resolved: ResolvedSidebarConfig,
 ): Promise<void> {
   try {