stack/apps/backend/src/stack.tsx

import { StackServerApp } from '@stackframe/stack';
import { getEnvVariable } from '@stackframe/stack-shared/dist/utils/env';

export function getStackServerApp() {
  // Fail fast if the backend self-URL env var is missing — without it the SDK
  // would silently inherit `defaultBaseUrl` (https://api.stack-auth.com), which
  // is almost never what we want for backend self-calls.
  //
  // We deliberately do NOT pass it as an explicit `baseUrl` to the SDK: doing
  // so collapses `resolveApiUrls` to a single-element URL list, which short-
  // circuits `_withFallback` (`apiUrls.length <= 1` branch). The SDK reads the
  // same env var internally and additionally appends its hardcoded fallback
  // URLs, which is what the e2e-fallback-tests workflow relies on so backend
  // self-calls (quota debits in email-queue-step, send-test-email, analytics
  // events batch, etc.) survive a primary-port outage.
  getEnvVariable('NEXT_PUBLIC_STACK_API_URL');
  return new StackServerApp({
    projectId: 'internal',
    tokenStore: null,
    publishableClientKey: getEnvVariable('STACK_INTERNAL_PROJECT_PUBLISHABLE_CLIENT_KEY'),
    secretServerKey: getEnvVariable('STACK_INTERNAL_PROJECT_SECRET_SERVER_KEY'),
  });
}