import { SystemPrompt } from '../system-prompts.js';
import { ModelMessage } from '../types.js';
/**
 * Remove lone surrogates from the text `chat()` sends to a provider. A lone
 * surrogate is invalid UTF-8 / JSON on the wire, so providers reject the
 * whole request.
 */
export declare function sanitizeProviderRequest(messages: Array<ModelMessage>, systemPrompts: Array<SystemPrompt> | undefined): {
    messages: {
        toolCalls?: Array<import('..').ToolCall>;
        content: string | (import('..').ImagePart<unknown> | import('..').AudioPart<unknown> | import('..').VideoPart<unknown> | import('..').DocumentPart<unknown> | {
            content: string;
            type: "text";
            metadata?: unknown;
        })[] | null;
        role: "user" | "assistant" | "tool";
        name?: string;
        toolCallId?: string;
        thinking?: Array<{
            content: string;
            signature?: string;
            redacted?: boolean;
        }>;
        error?: string;
        metadata?: Record<string, any>;
        structuredOutput?: import('..').StructuredOutputPart;
        id?: string;
        createdAt?: Date;
    }[];
    systemPrompts: (string | {
        content: string;
        metadata?: unknown;
    })[] | undefined;
};