import type { CompletionRequest } from '../../types/messages.js';
import type { AgentMiddleware } from '../create-agent.js';
/** One cleared result, for a custom placeholder. */
export interface ClearedToolResult {
    /** The tool whose result was cleared. */
    tool: string;
    /** How long the result was, in characters. */
    length: number;
}
/** What one edit did, for logs and for measuring what it saves. */
export interface ContextEdit {
    /** Tool results cleared. */
    cleared: number;
    /** The request's estimated tokens before. */
    tokensBefore: number;
    /** And after. */
    tokensAfter: number;
}
/** Options for `contextEditor()`. */
export interface ContextEditorOptions {
    /** Editing starts once the request's estimated tokens pass this. Defaults to 30,000. */
    triggerTokens?: number;
    /** The most recent tool results, kept whole. Defaults to 3. */
    keepToolResults?: number;
    /**
     * Results are cleared this many at a time, so the edited prefix stays the same for several calls
     * and a provider's prompt cache keeps working between edits. Defaults to 5.
     */
    batch?: number;
    /** Tools whose results are never cleared. */
    exclude?: readonly string[];
    /** Also empties the arguments of each call whose result is cleared, for tools that take large inputs. */
    clearArguments?: boolean;
    /** What a cleared result says instead. Defaults to a line naming the tool and how to get it back. */
    placeholder?: string | ((cleared: ClearedToolResult) => string);
    /** Estimates a request's tokens. Defaults to about four characters a token. */
    estimateTokens?: (request: CompletionRequest) => number;
    /** Called after each edit. */
    onEdit?: (edit: ContextEdit) => void;
}
/**
 * Clears old tool results from what the model is sent, once the request grows past a threshold.
 *
 * Tool output is most of a long agent's context, and the model rarely needs a result from twenty
 * steps ago verbatim. Every result but the most recent few is replaced by a short placeholder, in
 * batches, so the edited prefix stays the same between edits and a provider's prompt cache keeps
 * working. Only the request changes: the transcript in state keeps every result, and checkpoints,
 * events, and a later summary still see them.
 */
export declare function contextEditor(options?: ContextEditorOptions): AgentMiddleware;
/** About four characters a token, over the messages, the tool calls, and the tool schemas. */
export declare function estimateRequestTokens(request: CompletionRequest): number;