diff --git a/.changeset/prepare-specialized-app-signin-flow.md b/.changeset/prepare-specialized-app-signin-flow.md
index 03f37b7107..31d5bb1b8d 100644
--- a/.changeset/prepare-specialized-app-signin-flow.md
+++ b/.changeset/prepare-specialized-app-signin-flow.md
@@ -3,4 +3,4 @@
 '@backstage/frontend-defaults': patch
 ---
 
-Adds `prepareSpecializedApp` as a new two-phase app wiring API for rendering a sign-in page before full app finalization. The existing `createSpecializedApp` API is now deprecated and backed by `prepareSpecializedApp().finalize()`, while `createApp` has been updated to use the same prepare/finalize flow.
+Adds `prepareSpecializedApp` as a new two-phase app wiring API for rendering a sign-in page before full app finalization. Session preparation now resolves to an opaque reusable `sessionState`, which is returned from `getSignIn().ready` and from `finalize()`, and can be passed into a future `prepareSpecializedApp` call to skip sign-in and reuse the prepared session. The existing `createSpecializedApp` API is now deprecated and backed by `prepareSpecializedApp().finalize()`, while `createApp` has been updated to use the same prepare/finalize flow.
diff --git a/packages/frontend-app-api/src/wiring/createSpecializedApp.test.tsx b/packages/frontend-app-api/src/wiring/createSpecializedApp.test.tsx
index 788fc6bbc2..cd1356d4cb 100644
--- a/packages/frontend-app-api/src/wiring/createSpecializedApp.test.tsx
+++ b/packages/frontend-app-api/src/wiring/createSpecializedApp.test.tsx
@@ -1731,107 +1731,6 @@ describe('createSpecializedApp', () => {
       );
     });
 
-    it('should reuse predicate context gathered during sign-in completion', async () => {
-      const identityApi = {
-        getProfileInfo: async () => ({ displayName: 'Test User' }),
-        getBackstageIdentity: async () => ({
-          type: 'user' as const,
-          userEntityRef: 'user:default/test-user',
-          ownershipEntityRefs: ['user:default/test-user'],
-        }),
-        getCredentials: async () => ({ token: 'token' }),
-        signOut: async () => {},
-      };
-      const featureFlagsApi = {
-        isActive: jest.fn((name: string) => name === 'test-flag'),
-        registerFlag: jest.fn(),
-        getRegisteredFlags: () => [],
-        save: jest.fn(),
-      } as unknown as typeof featureFlagsApiRef.T;
-      const gatedAppPlugin = appPluginOriginal.withOverrides({
-        extensions: [
-          appPluginOriginal.getExtension('app/layout').override({
-            if: { featureFlags: { $contains: 'test-flag' } },
-            factory: () => [
-              coreExtensionData.reactElement(<div>Flagged Layout</div>),
-            ],
-          }),
-        ],
-      });
-
-      const preparedApp = prepareSpecializedApp({
-        features: [
-          gatedAppPlugin,
-          createFrontendModule({
-            pluginId: 'app',
-            extensions: [
-              ApiBlueprint.make({
-                params: defineParams =>
-                  defineParams({
-                    api: featureFlagsApiRef,
-                    deps: {},
-                    factory: () => featureFlagsApi,
-                  }),
-              }),
-              gatedAppPlugin.getExtension('sign-in-page:app').override({
-                factory: () => {
-                  function SignInPage(props: {
-                    onSignInSuccess(identity: IdentityApi): void;
-                  }) {
-                    useEffect(() => {
-                      props.onSignInSuccess(identityApi);
-                    }, [props]);
-                    return <div>Custom Sign In</div>;
-                  }
-
-                  return [signInPageComponentDataRef(SignInPage)];
-                },
-              }),
-            ],
-          }),
-        ],
-      });
-
-      const signIn = preparedApp.getSignIn();
-      render(signIn!.element);
-      await expect(
-        screen.findByText('Custom Sign In'),
-      ).resolves.toBeInTheDocument();
-
-      await signIn!.complete;
-      expect(featureFlagsApi.isActive).toHaveBeenCalledWith('test-flag');
-      expect(featureFlagsApi.isActive).toHaveBeenCalledTimes(1);
-
-      const finalizedApp = preparedApp.finalize();
-      render(
-        finalizedApp.tree.root.instance!.getData(
-          coreExtensionData.reactElement,
-        ),
-      );
-
-      expect(screen.getByText('Flagged Layout')).toBeInTheDocument();
-    });
-
-    it('should reject bootstrap-visible extensions that use if predicates', () => {
-      expect(() =>
-        prepareSpecializedApp({
-          features: [
-            appPluginOriginal,
-            createFrontendModule({
-              pluginId: 'app',
-              extensions: [
-                appPluginOriginal.getExtension('sign-in-page:app').override({
-                  if: { featureFlags: { $contains: 'test-flag' } },
-                }),
-              ],
-            }),
-          ],
-        }),
-      ).toThrow(
-        "Extension 'sign-in-page:app' uses 'if' before the session boundary at 'app/root.children'. Move it behind the session boundary or remove the predicate.",
-      );
-    });
-
     it('should gate finalize behind internal async sign-in finalization', async () => {
       const identityApi = {
         getProfileInfo: async () => ({ displayName: 'Test User' }),
diff --git a/packages/frontend-defaults/src/createApp.tsx b/packages/frontend-defaults/src/createApp.tsx
index 50f8db64f7..75d33282e7 100644
--- a/packages/frontend-defaults/src/createApp.tsx
+++ b/packages/frontend-defaults/src/createApp.tsx
@@ -126,17 +126,18 @@ export function createApp(options?: CreateAppOptions): {
       bindRoutes: options?.bindRoutes,
       advanced: options?.advanced,
     });
+    const signIn = preparedApp.getSignIn();
 
-    if (preparedApp.getSignIn()) {
+    if (signIn.element) {
       return {
         default: () => <PreparedAppRoot preparedApp={preparedApp} />,
       };
     }
 
-    await preparedApp.buildPredicateContext();
+    const { sessionState } = await signIn.ready;
 
     return {
-      default: () => renderFinalizedApp(preparedApp.finalize()),
+      default: () => renderFinalizedApp(preparedApp.finalize(sessionState)),
     };
   }
 
@@ -166,15 +167,11 @@ function PreparedAppRoot(props: {
     let cancelled = false;
     const runFinalize = async () => {
       try {
-        if (signIn) {
-          await signIn.complete;
-        } else {
-          await props.preparedApp.buildPredicateContext();
-        }
+        const { sessionState } = await signIn.ready;
         if (cancelled) {
           return;
         }
-        setFinalizedApp(props.preparedApp.finalize());
+        setFinalizedApp(props.preparedApp.finalize(sessionState));
       } catch (error) {
         if (cancelled) {
           return;
@@ -193,7 +190,7 @@ function PreparedAppRoot(props: {
   }
 
   if (!finalizedApp) {
-    return signIn?.element ?? <></>;
+    return signIn.element ?? <></>;
   }
 
   return renderFinalizedApp(finalizedApp);