import type { ProviderAgentInputItem, ProviderAgentOutputItem } from '../../lib/providers';
import type { AttachmentCache, AttachmentReferenceMap, ChatMessage } from './useChatAgent.types';
export type LegacyAgentMessage = {
    role: 'user' | 'assistant';
    content: string;
};
/**
 * Transforms chat history into both modern agent items and legacy fallbacks for compatibility layers.
 */
export declare const buildThreadVariants: (history: ChatMessage[]) => {
    modern: Array<ProviderAgentInputItem | ProviderAgentOutputItem>;
    legacy: LegacyAgentMessage[];
};
/**
 * Collects attachment metadata indexed by id so the agent can resolve cached files during a run.
 */
export declare const collectAttachmentContext: (history: ChatMessage[], cache: AttachmentCache) => AttachmentReferenceMap;
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