fix: Refined fix

Author: royanger

packages/react/src/__tests__/isomorphicClerk.test.ts

@@ -252,5 +252,37 @@ describe('isomorphicClerk', () => {
       // Should not attempt to load UI from CDN
       expect(loadClerkUIScript).not.toHaveBeenCalled();
     });
+
+    it('passes ui.ClerkUI to clerk.load even when standardBrowser is false', async () => {
+      const mockClerkUI = vi.fn();
+      const mockLoad = vi.fn().mockResolvedValue(undefined);
+      const mockClerkInstance = {
+        load: mockLoad,
+        loaded: false,
+      };
+
+      // Simulate chrome-extension with syncHost: Clerk instance + ui prop + standardBrowser: false
+      const clerk = new IsomorphicClerk({
+        publishableKey: 'pk_test_XXX',
+        Clerk: mockClerkInstance as any,
+        ui: { ClerkUI: mockClerkUI } as any,
+        standardBrowser: false,
+      });
+
+      (global as any).Clerk = mockClerkInstance;
+
+      await (clerk as any).getEntryChunks();
+
+      // clerk.load should have been called with ui.ClerkUI preserved
+      expect(mockLoad).toHaveBeenCalledWith(
+        expect.objectContaining({
+          ui: expect.objectContaining({
+            ClerkUI: mockClerkUI,
+          }),
+        }),
+      );
+      // Should not attempt to load UI from CDN
+      expect(loadClerkUIScript).not.toHaveBeenCalled();
+    });
   });
 });

packages/react/src/isomorphicClerk.ts

@@ -472,9 +472,11 @@ export class IsomorphicClerk implements IsomorphicLoadedClerk {
 
       if (!clerk.loaded) {
         this.beforeLoad(clerk);
-        // Load UI in standard browser environments, or when a bundled ClerkUI is provided via the ui prop
+        // Load UI when:
+        // - standard browser and no pre-created Clerk instance (normal CDN path), OR
+        // - a bundled ClerkUI was provided via the ui prop (e.g. chrome-extension, even with standardBrowser: false)
         const shouldLoadUi =
-          this.options.standardBrowser !== false && (!this.options.Clerk || this.options.ui?.ClerkUI);
+          (this.options.standardBrowser !== false && !this.options.Clerk) || !!this.options.ui?.ClerkUI;
         const ClerkUI = shouldLoadUi ? await this.getClerkUIEntryChunk() : undefined;
         await clerk.load({ ...this.options, ui: { ...this.options.ui, ClerkUI } });
       }