fix(clerk-js): Always pass domain to createFapiClient()

.changeset/chatty-lemons-hug.md

@@ -0,0 +1,5 @@
+---
+'@clerk/clerk-js': patch
+---
+
+Fixes an issue where Clerk's internal API client was using the incorrect domain for satellite apps.

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

@@ -2051,6 +2051,35 @@ describe('Clerk singleton', () => {
     });
   });
 
+  describe('Clerk multi-domain', () => {
+    describe('when development satellite', () => {
+      it('fapiClient should not use Clerk.domain as its baseUrl', async () => {
+        const sut = new Clerk(developmentPublishableKey, {
+          domain: 'satellite.dev',
+        });
+        await sut.load({
+          isSatellite: true,
+          signInUrl: 'https://primary.dev/sign-in',
+        });
+
+        expect(sut.getFapiClient().buildUrl({ path: '/me' }).href).toContain(`https://${sut.frontendApi}/v1/me`);
+      });
+    });
+
+    describe('when production satellite', () => {
+      test('fapiClient should use Clerk.domain as its baseUrl', async () => {
+        const sut = new Clerk(productionPublishableKey, {
+          domain: 'satellite.com',
+        });
+        await sut.load({
+          isSatellite: true,
+        });
+
+        expect(sut.getFapiClient().buildUrl({ path: '/me' }).href).toContain('https://clerk.satellite.com/v1/me');
+      });
+    });
+  });
+
   describe('buildUrlWithAuth', () => {
     it('builds an absolute url from a relative url in development', async () => {
       const sut = new Clerk(developmentPublishableKey);

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

@@ -75,6 +75,14 @@ describe('buildUrl(options)', () => {
     );
   });
 
+  it('uses domain from options if production', () => {
+    expect(
+      createFapiClient({ ...baseFapiClientOptions, domain: 'clerk.other.com', instanceType: 'production' }).buildUrl({
+        path: '/foo',
+      }).href,
+    ).toBe(`https://clerk.other.com/v1/foo?__clerk_api_version=${SUPPORTED_FAPI_VERSION}&_clerk_js_version=test`);
+  });
+
   it('adds _clerk_session_id as a query parameter if provided and path does not start with client or waitlist', () => {
     expect(fapiClient.buildUrl({ path: '/foo', sessionId: 'sess_42' }).href).toBe(
       `https://clerk.example.com/v1/foo?__clerk_api_version=${SUPPORTED_FAPI_VERSION}&_clerk_js_version=test&_clerk_session_id=sess_42`,

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

@@ -306,10 +306,11 @@ export class Clerk implements ClerkInterface {
     this.#instanceType = publishableKey.instanceType;
 
     this.#fapiClient = createFapiClient({
-      domain: (this.instanceType === 'development' && this.isSatellite && this.domain) || undefined,
+      domain: this.domain,
       frontendApi: this.frontendApi,
       // this.instanceType is assigned above
       instanceType: this.instanceType as InstanceType,
+      isSatellite: this.isSatellite,
       getSessionId: () => {
         return this.session?.id;
       },

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

@@ -67,6 +67,7 @@ type FapiClientOptions = {
   proxyUrl?: string;
   instanceType: InstanceType;
   getSessionId: () => string | undefined;
+  isSatellite?: boolean;
 };
 
 export function createFapiClient(options: FapiClientOptions): FapiClient {
@@ -114,7 +115,7 @@ export function createFapiClient(options: FapiClientOptions): FapiClient {
       searchParams.append('rotating_token_nonce', rotatingTokenNonce);
     }
 
-    if (options.domain) {
+    if (options.domain && options.instanceType === 'development' && options.isSatellite) {
       searchParams.append('__domain', options.domain);
     }
 
@@ -144,8 +145,6 @@ export function createFapiClient(options: FapiClientOptions): FapiClient {
   function buildUrl(requestInit: FapiRequestInit): URL {
     const { path, pathPrefix = 'v1' } = requestInit;
 
-    const domainOnlyInProd = options.instanceType === 'production' ? options.domain : '';
-
     if (options.proxyUrl) {
       const proxyBase = new URL(options.proxyUrl);
       const proxyPath = proxyBase.pathname.slice(1, proxyBase.pathname.length);
@@ -159,6 +158,9 @@ export function createFapiClient(options: FapiClientOptions): FapiClient {
       );
     }
 
+    // We only use the domain option in production, in development it should always match the frontendApi
+    const domainOnlyInProd = options.instanceType === 'production' ? options.domain : '';
+
     const baseUrl = `https://${domainOnlyInProd || options.frontendApi}`;
 
     return buildUrlUtil(