import type { HarnessStepResult } from "#harness/step-hooks.js";
/** How a recovery reissues the call. */
type RecoveryCall = (options: {
    readonly disabledProviderTools?: ReadonlySet<string>;
    readonly extraSystemNote?: string;
    readonly retryReason?: "empty-response";
    readonly suppressStepStartedEmission?: boolean;
    readonly trailingUserNote?: string;
}) => Promise<HarnessStepResult>;
/**
 * Recovers a failed model call, each recovery at most once and within the current step, so the
 * reissue suppresses a second `step.started`:
 *
 * 1. The host rejected a provider-specific tool it can't serve (an AI Gateway fallback provider,
 *    or an OpenAI-compatible endpoint without OpenAI web search): the call is reissued without
 *    it, and a system note tells the model which capability went away. Only known provider tools
 *    are dropped, never an authored one.
 * 2. The response was empty (see {@link EmptyModelResponseError}), including the first
 *    recovery's: the call is reissued with {@link EMPTY_RESPONSE_NUDGE}, repeating what the first
 *    recovery removed.
 *
 * Each reissue goes through `call` so it gets fresh step hooks: the failed attempt's one-shot
 * `stepResult` already resolved. Returns the error that remains when nothing recovered.
 */
export declare function recoverModelCall(input: {
    readonly error: unknown;
    readonly call: RecoveryCall;
    readonly sessionId: string;
    readonly turnId: string;
}): Promise<{
    readonly result: HarnessStepResult;
} | {
    readonly error: unknown;
}>;
/**
 * True when a step produced no assistant text and no tool calls. A blank
 * response is ambiguous and must be retried instead of silently dropping a
 * HITL reply.
 */
export declare function isEmptyModelResponse(step: HarnessStepResult): boolean;
/**
 * Rethrows the AI SDK's `NoOutputGeneratedError` as
 * {@link EmptyModelResponseError}. Since `ai@7.0.0-canary.169`
 * (vercel/ai#15938) a stream that closes after metadata without output or
 * a finish chunk rejects — the SDK enqueues the error onto `fullStream`
 * (so `emitStreamContent` throws it) and never emits `finish-step`, so
 * `onStepEnd` does not fire and the step hooks' `stepResult` promise
 * would never settle. The same condition previously completed as an empty
 * step caught by {@link isEmptyModelResponse}; normalizing here funnels
 * both shapes into the one-shot empty-response reissue.
 */
export declare function rethrowNoOutputAsEmptyResponse(error: unknown): never;
export {};