refactor: establish standalone application boundary

app/frontend/pages/runtime.js

@@ -2,6 +2,7 @@
   "use strict";
 
   const definitions = new Map();
+  const featureBindings = new Map();
   let sealed = false;
 
   function register(feature, viewIds, lifecycle = {}) {
@@ -9,6 +10,13 @@
     if (!feature || !Array.isArray(viewIds) || !viewIds.length) {
       throw new Error("Page modules require a feature and at least one view ID");
     }
+    if (typeof lifecycle.bind === "function") {
+      const existing = featureBindings.get(feature);
+      if (existing && existing !== lifecycle.bind) {
+        throw new Error(`Duplicate feature binding owner: ${feature}`);
+      }
+      featureBindings.set(feature, lifecycle.bind);
+    }
     viewIds.forEach((viewId) => {
       if (definitions.has(viewId)) throw new Error(`Duplicate page module: ${viewId}`);
       definitions.set(viewId, Object.freeze({
@@ -26,6 +34,13 @@
     const actions = Object.freeze({ ...(options.actions || {}) });
     const missing = pages.all.filter((page) => !definitions.has(page.id)).map((page) => page.id);
     if (missing.length) throw new Error(`Missing page modules: ${missing.join(", ")}`);
+    let eventsBound = false;
+
+    function bind() {
+      if (eventsBound) return;
+      eventsBound = true;
+      featureBindings.forEach((handler) => handler());
+    }
 
     function run(actionNames, context) {
       actionNames.forEach((actionName) => {
@@ -51,6 +66,7 @@
     return Object.freeze({
       afterMount,
       beforeMount,
+      bind,
       get: (viewId) => definitions.get(viewId) || null,
       has: (viewId) => definitions.has(viewId),
     });