diff --git a/js/app.js b/js/app.js
index 6374f47b..9636cfba 100644
--- a/js/app.js
+++ b/js/app.js
@@ -247,7 +247,16 @@ class Application {
   }
 
   constructor({ services = {}, ui = {}, helpers = {}, loadView: viewLoader } = {}) {
-    this.loadView = viewLoader || null;
+    this.loadView = typeof viewLoader === "function" ? viewLoader : null;
+    this._setupOptions = { services, ui, helpers };
+    this._isSetup = false;
+  }
+
+  setup() {
+    if (this._isSetup) return;
+    this._isSetup = true;
+
+    const { services = {}, ui = {}, helpers = {} } = this._setupOptions || {};
 
     const bootstrapServices = {
       ...services,
@@ -509,6 +518,8 @@ class Application {
     };
     onActiveSignerChanged(this.handleShareNostrSignerChange);
     this.updateShareNostrAuthState({ reason: "init" });
+
+    delete this._setupOptions;
   }
 
   /**
diff --git a/js/bootstrap.js b/js/bootstrap.js
index b8e82d8b..bcbfa1b3 100644
--- a/js/bootstrap.js
+++ b/js/bootstrap.js
@@ -30,10 +30,12 @@ function mergeServices(overrides = {}) {
 }
 
 export async function createApplication({ services, loadView: loadViewOverride } = {}) {
-  return new Application({
+  const app = new Application({
     services: mergeServices(services),
     loadView: typeof loadViewOverride === "function" ? loadViewOverride : loadView,
   });
+  app.setup();
+  return app;
 }
 
 export default createApplication;
diff --git a/js/embed.js b/js/embed.js
index a6f76577..fec5d152 100644
--- a/js/embed.js
+++ b/js/embed.js
@@ -102,6 +102,8 @@ app.showSuccess = (message) => {
   setStatus(message, "success");
 };
 
+app.setup();
+
 const resolvePlaybackPreference = (value) => {
   if (typeof value !== "string") {
     return null;
diff --git a/tests/video-modal-accessibility.test.mjs b/tests/video-modal-accessibility.test.mjs
index ebfaebfd..7401f3cf 100644
--- a/tests/video-modal-accessibility.test.mjs
+++ b/tests/video-modal-accessibility.test.mjs
@@ -599,6 +599,7 @@ async function setupPlaybackHarness() {
     helpers,
     ui: { videoModal: () => modalStub },
   });
+  app.setup();
 
   app.showError = () => {};
   app.showSuccess = () => {};
diff --git a/tests/video-modal-zap.test.mjs b/tests/video-modal-zap.test.mjs
index 0a1ae2bd..c529d0fd 100644
--- a/tests/video-modal-zap.test.mjs
+++ b/tests/video-modal-zap.test.mjs
@@ -143,7 +143,15 @@ if (typeof globalThis.WebSocket === "undefined") {
 }
 
 globalThis.document = documentStub;
-globalThis.navigator = windowStub.navigator;
+try {
+  Object.defineProperty(globalThis, "navigator", {
+    value: windowStub.navigator,
+    writable: true,
+    configurable: true,
+  });
+} catch (e) {
+  // Fallback for environments where navigator is read-only
+}
 globalThis.location = windowStub.location;
 
 if (typeof globalThis.fetch === "undefined") {
@@ -302,6 +310,7 @@ async function createApp({ splitAndZap }) {
       videoModal: () => modalStub,
     },
   });
+  app.setup();
 
   app.boundVideoModalZapOpenHandler = (event = {}) => {
     const requiresLogin = Boolean(event?.detail?.requiresLogin);