/**
 * The fetch implementation used by the HTTP providers (zai/deepseek). A
 * neutral, provider-agnostic alias so shared call sites (e.g. the dispatcher
 * factory's test-injectable `fetchImpl`) don't have to borrow one provider's
 * name. Equal to undici's `fetch` type; `ZaiFetch`/`DeepseekFetch` are the
 * same type under provider-specific names. Uses a type-only `import()` so no
 * runtime dependency is added to this leaf module.
 */
export type ProviderFetch = typeof import('undici').fetch;
/**
 * Error thrown by a provider dispatcher, carrying whether the failure is
 * worth failing over to a secondary provider.
 *
 * `retryable: false` marks a PERMANENT failure the fallback must NOT swallow
 * — a bad/missing API key (401/403) or a malformed request (400) cannot be
 * fixed by a second provider, and a silent failover would hide the
 * misconfiguration and let the cron "succeed" without ever using the
 * intended primary provider.
 */
export declare class DispatcherError extends Error {
    readonly retryable: boolean;
    constructor(message: string, opts: {
        retryable: boolean;
    });
}
/**
 * Classify an HTTP status from a provider's chat-completions endpoint as
 * retryable (worth failing over) or not.
 *
 * - 408 (Request Timeout) and 429 (Too Many Requests) are transient → retry.
 * - 5xx are server-side and transient → retry.
 * - Any other 4xx (400/401/403/404/…) is a permanent client error
 *   (bad key, malformed request, wrong endpoint) → do NOT retry; surface it.
 *
 * In practice this is only ever called for a non-2xx status (the dispatchers
 * invoke it inside their `status < 200 || status >= 300` branch, and undici
 * follows 3xx redirects itself), so the final `< 400` fall-through is just a
 * safe "treat anything unexpected as retryable" default.
 */
export declare function isRetryableHttpStatus(status: number): boolean;
/**
 * Pull a useful message out of a thrown fetch error. undici wraps
 * transport-layer failures (DNS, connection reset, TLS) in a
 * `TypeError: fetch failed` whose `cause` carries the actionable detail
 * (ENOTFOUND, ECONNRESET, etc.). Without unwrapping `cause`, cron logs would
 * lose that detail and show only "fetch failed" — useless for triage. Shared
 * by the zai and deepseek dispatchers so the unwrapping logic lives in one
 * place.
 */
export declare function describeFetchError(err: unknown): string;
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