Function formatKiloChatError

packages/kilo-chat/src/errors.ts:26–45

(err: unknown, fallback: string)

  | { kind: 'title-too-long'; limit: number }
  | { kind: 'message-empty' }
  | { kind: 'server'; message: string }
  | { kind: 'fallback' };

/**
 * Classify an error thrown by `KiloChatClient`.
 *
 * - Non-{@link KiloChatApiError} (network/abort/timeout) → `fallback`.
 * - 401/403 → `not-allowed` (avoids leaking server phrasing).
 * - 4xx with a zod `issues` array → classify the first known issue; otherwise
 *   surface the server's `error` string when present as `server`.
 * - 5xx / unknown → `fallback`.
 *
 * Callers that need custom branching (e.g. 409 edit conflicts) should check
 * `err instanceof KiloChatApiError` themselves before delegating here.
 */
export function classifyKiloChatError(err: unknown): KiloChatErrorKind {
  if (!(err instanceof KiloChatApiError)) return { kind: 'fallback' };

  if (err.status === 401 || err.status === 403) return { kind: 'not-allowed' };
  if (err.status >= 500) return { kind: 'fallback' };

  const body = err.body;
  if (!body || typeof body !== 'object') return { kind: 'fallback' };