claude-code-proxy/shared/frontend/backend.ts

export const DEFAULT_BACKEND_ORIGIN = 'http://localhost:3001';

export function resolveBackendOrigin(env: Record<string, string | undefined>): string {
  return (env.BACKEND_URL || env.PROXY_BACKEND_URL || DEFAULT_BACKEND_ORIGIN).replace(/\/$/, '');
}

export function buildBackendURL(origin: string, path: string, searchParams?: URLSearchParams): string {
  const url = new URL(path, `${origin}/`);
  if (searchParams) {
    url.search = searchParams.toString();
  }
  return url.toString();
}