docs(workspace): explain component state and async ownership

src/components/workspace/canvas-runtime-host.tsx

@@ -23,6 +23,7 @@ const Renderers=createContext(defaultCanvasRenderers);
 export function useCanvasRenderers(){return useContext(Renderers);}
 /** extensions仅在useState惰性初始化时捕获；后续prop换引用不会热替换已打开项目的schema/renderer。 */
 export function CanvasRuntimeHost({ children,extensions=[] }: { children: ReactNode;extensions?:readonly CanvasRuntimeExtension[] }) {
+  // 惰性初始化只装配对象/工厂，不在 render 直接打开项目；实际账户绑定和持久化租约由后续调用取得。
   const [{host,renderers}] = useState(() => {
     // 先组合内置与扩展模型，再按精确版本/结构验证renderer，冲突在打开项目之前失败。
     const registry = createRegistry([...builtinComponents(),...extensions.flatMap(extension=>extension.components??[])]),renderers=createReactRenderers([...defaultCanvasRenderers.definitions,...extensions.flatMap(extension=>extension.renderers??[])],registry);
@@ -51,6 +52,7 @@ export function CanvasRuntimeHost({ children,extensions=[] }: { children: ReactN
    * 真正卸载才发起host.close，保存失败由宿主错误回调/日志报告，不在此丢弃根或强行释放leader。 */
   useEffect(() => {
     const generation = ++lifetime.current;
+    // cleanup 不等待 close 完成，也不主动重试；异步失败经 host 的错误通道和此处 catch 报告。
     // Strict Mode replays effects synchronously; only a real detach retires the host.
     return () => { queueMicrotask(() => { if (lifetime.current === generation) void host.close().catch(error => console.error("[canvas-host]", error.message)); }); };
   }, [host]);