Function assertDispatchNamesUnique

showcase/scripts/railway-envs.ts:2275–2307

(
  services: Record<string, { dispatchName?: string }> = SERVICES,
)

 * Accepts an injected map for testing; defaults to the real SERVICES map.
 */
export function assertDispatchNamesUnique(
  services: Record<string, { dispatchName?: string }> = SERVICES,
): void {
  const seen = new Map<string, string>(); // dispatchName -> first ssotKey
  const problems: string[] = [];
  for (const [key, entry] of Object.entries(services)) {
    const dn = entry.dispatchName;
    if (typeof dn !== "string" || dn.length === 0) continue;
    const prior = seen.get(dn);
    if (prior !== undefined) {
      problems.push(
        `  - duplicate dispatchName "${dn}" on SSOT keys: ${prior}, ${key}`,
      );
    } else {
      seen.set(dn, key);
    }
    // Own-property lookup (same rationale as elsewhere in this file): an
    // inherited Object.prototype key must not register as a collision.
    if (dn !== key && Object.hasOwn(services, dn)) {
      problems.push(
        `  - dispatchName "${dn}" on SSOT key "${key}" equals a DIFFERENT entry's SSOT key — resolveTargetServices resolves SSOT keys first, so this dispatch_name would silently misroute to "${dn}"`,
      );
    }
  }
  if (problems.length > 0) {
    throw new Error(
      `railway-envs SSOT invariant violated:\n${problems.join("\n")}\n` +
        `Fix: each Railway service must have a unique dispatchName that ` +
        `does not collide with another entry's SSOT key ` +
        `(or no dispatchName at all for out-of-band services).`,
    );
  }
}

/**
 * Throw on SSOT load if any `imageOf` is mis-wired. A dangling target,