[Init] Initial commit - NetMesh terminal manager

application/app/appHandlersBridge.ts

@@ -0,0 +1,64 @@
+/**
+ * Stable accessor bridge for App-local handlers that Host islands need when
+ * assembling domain bags. `AppSideEffects` registers the live glue via
+ * `useLayoutEffect`; Hosts call `getAppHandlers()` instead of receiving mega
+ * props from App.
+ *
+ * Keep this intentionally loose (`Record<string, unknown>`): the handler set
+ * tracks App glue, not a frozen public API.
+ */
+
+type Listener = () => void;
+
+export type AppHandlers = Record<string, unknown>;
+
+function handlersShallowEqual(prev: AppHandlers, next: AppHandlers): boolean {
+  const prevKeys = Object.keys(prev);
+  const nextKeys = Object.keys(next);
+  if (prevKeys.length !== nextKeys.length) return false;
+  for (const key of nextKeys) {
+    if (prev[key] !== next[key]) return false;
+  }
+  return true;
+}
+
+class AppHandlersBridge {
+  private handlers: AppHandlers | null = null;
+  private listeners = new Set<Listener>();
+
+  get = (): AppHandlers | null => this.handlers;
+
+  subscribe = (listener: Listener): (() => void) => {
+    this.listeners.add(listener);
+    return () => {
+      this.listeners.delete(listener);
+    };
+  };
+
+  set(next: AppHandlers | null): void {
+    if (this.handlers === next) return;
+    if (
+      this.handlers
+      && next
+      && handlersShallowEqual(this.handlers, next)
+    ) {
+      return;
+    }
+    this.handlers = next;
+    for (const listener of this.listeners) listener();
+  }
+}
+
+const bridge = new AppHandlersBridge();
+
+export function registerAppHandlers(handlers: AppHandlers | null): void {
+  bridge.set(handlers);
+}
+
+export function getAppHandlers(): AppHandlers | null {
+  return bridge.get();
+}
+
+export function subscribeAppHandlers(listener: Listener): () => void {
+  return bridge.subscribe(listener);
+}