fix(api): share base-domain API host

Tenant subdomains route through api.<base-domain>; nginx forwards the exact storefront host derived from the validated browser origin.

src/app/core/config/api-config.service.spec.ts

@@ -9,8 +9,9 @@ describe('ApiConfigService', () => {
   beforeEach(() => {
     tenantResolver = jasmine.createSpyObj<TenantResolverService>(
       'TenantResolverService',
-      ['getHostname', 'getProtocol', 'getTenantKey', 'isLocalhost']
+      ['getHostname', 'getBaseDomain', 'getProtocol', 'getTenantKey', 'isLocalhost']
     );
+    tenantResolver.getBaseDomain.and.returnValue('gorbushka.market');
     tenantResolver.getTenantKey.and.returnValue('gorbushka');
     tenantResolver.getProtocol.and.returnValue('https:');
     tenantResolver.isLocalhost.and.returnValue(false);
@@ -31,16 +32,17 @@ describe('ApiConfigService', () => {
     expect(service.getBaseUrl()).toBe('https://api.gorbushka.market');
   });
 
-  it('preserves every storefront subdomain in the API hostname', () => {
+  it('uses the shared base-domain API for a tenant subdomain', () => {
     tenantResolver.getHostname.and.returnValue('store1.example.com');
+    tenantResolver.getBaseDomain.and.returnValue('example.com');
 
-    expect(service.getBaseUrl()).toBe('https://api.store1.example.com');
+    expect(service.getBaseUrl()).toBe('https://api.example.com');
   });
 
-  it('preserves www like any other storefront subdomain', () => {
+  it('uses the shared base-domain API for www', () => {
     tenantResolver.getHostname.and.returnValue('www.gorbushka.market');
 
-    expect(service.getBaseUrl()).toBe('https://api.www.gorbushka.market');
+    expect(service.getBaseUrl()).toBe('https://api.gorbushka.market');
   });
 
   it('preserves the API namespace when targeting a tenant backend', () => {

src/app/core/config/api-config.service.ts

@@ -8,6 +8,7 @@ export class ApiConfigService {
 
   getBaseUrl(): string {
     const hostname = this.tenantResolver.getHostname();
+    const baseDomain = this.tenantResolver.getBaseDomain();
     const protocol = this.tenantResolver.getProtocol();
     const tenantKey = this.tenantResolver.getTenantKey();
     const tenantMap = (environment as any).tenantApiBaseUrls as Record<string, string> | undefined;
@@ -25,6 +26,7 @@ export class ApiConfigService {
     } else if (apiTemplate && hostname) {
       url = apiTemplate
         .replace('{protocol}', protocol)
+        .replace('{baseDomain}', baseDomain)
         .replace('{hostname}', hostname)
         .replace('{tenant}', tenantKey);
     }

src/app/core/config/tenant-resolver.service.spec.ts

@@ -0,0 +1,33 @@
+import { DOCUMENT } from '@angular/common';
+import { TestBed } from '@angular/core/testing';
+import { TenantResolverService } from './tenant-resolver.service';
+
+describe('TenantResolverService', () => {
+  function resolveBaseDomain(hostname: string): string {
+    TestBed.resetTestingModule();
+    TestBed.configureTestingModule({
+      providers: [
+        TenantResolverService,
+        {
+          provide: DOCUMENT,
+          useValue: { location: { hostname, protocol: 'https:' } }
+        }
+      ]
+    });
+
+    return TestBed.inject(TenantResolverService).getBaseDomain();
+  }
+
+  it('keeps a root storefront domain', () => {
+    expect(resolveBaseDomain('example.com')).toBe('example.com');
+  });
+
+  it('removes tenant and www subdomains from the API domain', () => {
+    expect(resolveBaseDomain('store1.example.com')).toBe('example.com');
+    expect(resolveBaseDomain('www.example.com')).toBe('example.com');
+  });
+
+  it('keeps a country-code second-level domain', () => {
+    expect(resolveBaseDomain('store1.example.co.uk')).toBe('example.co.uk');
+  });
+});

src/app/core/config/tenant-resolver.service.ts

@@ -15,6 +15,20 @@ export class TenantResolverService {
     return this.document?.location?.protocol ?? 'https:';
   }
 
+  getBaseDomain(): string {
+    const segments = this.getHostname().split('.').filter(Boolean);
+    if (segments.length <= 2) {
+      return segments.join('.');
+    }
+
+    const topLevelDomain = segments.at(-1) ?? '';
+    const secondLevelDomain = segments.at(-2) ?? '';
+    const usesCountryCodeSecondLevel =
+      topLevelDomain.length === 2 && secondLevelDomain.length <= 3;
+
+    return segments.slice(usesCountryCodeSecondLevel ? -3 : -2).join('.');
+  }
+
   isLocalhost(): boolean {
     const hostname = this.getHostname();
     return hostname === 'localhost' || hostname === '127.0.0.1' || hostname === '::1';

src/environments/environment.production.ts

@@ -4,7 +4,7 @@ export const environment = {
   useMockBootstrapOnLocal: false,
   fallbackTenantKey: 'default',
   localhostApiUrl: '/api',
-  tenantApiTemplate: '{protocol}//api.{hostname}',
+  tenantApiTemplate: '{protocol}//api.{baseDomain}',
   tenantApiBaseUrls: {},
   brandName: 'Marketplace',
   brandFullName: 'Marketplace',

src/environments/environment.ts

@@ -5,7 +5,7 @@ export const environment = {
   useMockBootstrapOnLocal: true,
   fallbackTenantKey: 'default',
   localhostApiUrl: '/api',
-  tenantApiTemplate: '{protocol}//api.{hostname}',
+  tenantApiTemplate: '{protocol}//api.{baseDomain}',
   tenantApiBaseUrls: {},
   brandName: 'Marketplace',
   brandFullName: 'Marketplace',