/**
 * Default backend base URL — the operator-set fallback used when no specific
 * instance is active. Resolution order:
 *
 *   1. window.__APP_CONFIG__.apiBaseUrl  — runtime, injected by the container
 *      at start from $PUBLIC_API_BASE_URL (see public/config.js). Lets one
 *      prebuilt image point at any backend origin without rebuilding.
 *   2. import.meta.env.PUBLIC_API_BASE_URL — build-time default (rsbuild inlines
 *      PUBLIC_* vars). Used in local dev and as a baked fallback.
 *   3. '/api/v1' — same-origin relative path (works behind a reverse proxy).
 *
 * The user's chosen instance still wins over all of these — see
 * runtime-config.ts / instances.ts.
 */
function runtimeApiBaseUrl(): string | undefined {
  if (typeof window === 'undefined') return undefined;
  const value = window.__APP_CONFIG__?.apiBaseUrl;
  return value ? value : undefined;
}

export const DEFAULT_API_BASE_URL =
  runtimeApiBaseUrl() ?? import.meta.env.PUBLIC_API_BASE_URL ?? '/api/v1';