fix(clerk-js): use custom signInUrl for factor-one and factor-two URLs in OAuth callbacks

.changeset/fix-factor-one-custom-signin-url.md

@@ -0,0 +1,5 @@
+---
+"@clerk/clerk-js": patch
+---
+
+fix(clerk-js): OAuth callbacks now respect custom sign-in URLs when routing to factor-one or factor-two. When a custom `signInUrl` is provided via `handleRedirectCallback`, the factor selection pages will be built from that URL instead of the dashboard-configured default, ensuring a consistent sign-in experience for custom integrations.

packages/clerk-js/src/core/__tests__/clerk.test.ts

@@ -2515,6 +2515,46 @@ describe('Clerk singleton', () => {
       });
     });
 
+    it('builds the factor-two URL from the signInUrl param when provided', async () => {
+      mockEnvironmentFetch.mockReturnValue(
+        Promise.resolve({
+          authConfig: {},
+          userSettings: mockUserSettings,
+          displayConfig: mockDisplayConfig,
+          isSingleSession: () => false,
+          isProduction: () => false,
+          isDevelopmentOrStaging: () => true,
+          onWindowLocationHost: () => false,
+        }),
+      );
+
+      mockClientFetch.mockReturnValue(
+        Promise.resolve({
+          signedInSessions: [],
+          signIn: new SignIn({
+            status: 'needs_second_factor',
+            first_factor_verification: {
+              status: 'verified',
+              strategy: 'oauth_google',
+              external_verification_redirect_url: null,
+              error: null,
+            },
+            second_factor_verification: null,
+          } as any as SignInJSON),
+          signUp: new SignUp(null),
+        }),
+      );
+
+      const sut = new Clerk(productionPublishableKey);
+      await sut.load(mockedLoadOptions);
+
+      await sut.handleRedirectCallback({ signInUrl: '/custom-sign-in' });
+
+      await waitFor(() => {
+        expect(mockNavigate.mock.calls[0][0]).toBe('/custom-sign-in#/factor-two');
+      });
+    });
+
     it('redirects an existing user to a custom 2fa page if 2fa is enabled and secondFactorUrl is passed during sign in', async () => {
       mockEnvironmentFetch.mockReturnValue(
         Promise.resolve({
@@ -2858,6 +2898,42 @@ describe('Clerk singleton', () => {
       });
     });
 
+    it('builds the factor-one URL from the signInUrl param when provided', async () => {
+      mockEnvironmentFetch.mockReturnValue(
+        Promise.resolve({
+          authConfig: {},
+          userSettings: mockUserSettings,
+          displayConfig: mockDisplayConfig,
+          isSingleSession: () => false,
+          isProduction: () => false,
+          isDevelopmentOrStaging: () => true,
+        }),
+      );
+
+      mockClientFetch.mockReturnValue(
+        Promise.resolve({
+          signedInSessions: [],
+          signIn: new SignIn({
+            status: 'needs_first_factor',
+            supported_first_factors: [
+              { strategy: 'enterprise_sso', enterprise_connection_id: 'ec_1', enterprise_connection_name: 'A' },
+              { strategy: 'enterprise_sso', enterprise_connection_id: 'ec_2', enterprise_connection_name: 'B' },
+            ],
+          } as unknown as SignInJSON),
+          signUp: new SignUp(null),
+        }),
+      );
+
+      const sut = new Clerk(productionPublishableKey);
+      await sut.load(mockedLoadOptions);
+
+      await sut.handleRedirectCallback({ signInUrl: '/custom-sign-in' });
+
+      await waitFor(() => {
+        expect(mockNavigate.mock.calls[0][0]).toBe('/custom-sign-in#/factor-one');
+      });
+    });
+
     it('redirects user to sign-in when a single bare enterprise_sso factor needs the first factor', async () => {
       mockEnvironmentFetch.mockReturnValue(
         Promise.resolve({

packages/clerk-js/src/core/clerk.ts

@@ -2688,12 +2688,12 @@ export class Clerk implements ClerkInterface {
 
     const navigateToFactorOne = makeNavigate(
       params.firstFactorUrl ||
-        buildURL({ base: displayConfig.signInUrl, hashPath: '/factor-one' }, { stringify: true }),
+        buildURL({ base: params.signInUrl || displayConfig.signInUrl, hashPath: '/factor-one' }, { stringify: true }),
     );
 
     const navigateToFactorTwo = makeNavigate(
       params.secondFactorUrl ||
-        buildURL({ base: displayConfig.signInUrl, hashPath: '/factor-two' }, { stringify: true }),
+        buildURL({ base: params.signInUrl || displayConfig.signInUrl, hashPath: '/factor-two' }, { stringify: true }),
     );
 
     const navigateToResetPassword = makeNavigate(