export declare const DEFAULT_MODEL_TTFB_TIMEOUT_MS = 180000;
export declare function resolveTtfbTimeoutMs(): number;
export declare const TTFB_TIMEOUT_MESSAGE = "model_ttfb_timeout";
export declare const TTFB_THROTTLE_SLACK_MS = 30000;
export declare const SDK_HONORED_RETRY_AFTER_CEILING_MS = 60000;
export declare const SDK_MAX_DEFAULT_BACKOFF_MS = 8000;
export declare function throttleExtensionMs(retryAfterMs: number | undefined): number | undefined;
export declare function isTtfbTimeoutError(err: unknown): boolean;
export interface FirstByteTimeoutHandle {
    readonly signal: AbortSignal;
    timedOut(): boolean;
    firstByteSeen(): void;
    extend(ms: number): void;
    dispose(): void;
}
export declare function armFirstByteTimeout(baseSignal: AbortSignal, timeoutMs: number): FirstByteTimeoutHandle;