import type { MessageLike } from "./types";
/** Only old, verified successful tool outputs are eligible for projection. */
export interface DtcConfig {
    protectRecentSteps: number;
    protectRecentTokens: number;
    targetRatio: number;
    minimumSavingsTokens: number;
    /** Additional protected tool names; never expands the built-in candidate set. */
    protectedTools: string[];
}
export declare const DTC_DEFAULTS: DtcConfig;
export interface TransformStats {
    foldedTools: number;
    /** Subset folded before unique outputs because a later identical result was visible. */
    redundantTools: number;
    estimatedBefore: number | undefined;
    estimatedAfter: number | undefined;
    targetTokens: number;
    protectedSteps: number;
    overBudget: boolean;
    skipped?: "invalid-budget" | "unknown-content";
}
export interface ProjectionOptions {
    inputBudget: number;
    config: DtcConfig;
    /** This projection only: do not bypass protections or change future policy. */
    force?: boolean;
    now?: number;
}
export interface ProjectionResult {
    messages: MessageLike[];
    stats: TransformStats;
}
/** Approximate visible request payload, including full inputs of compacted tools.
 * Undefined means that media or an unfamiliar host shape cannot be estimated. */
export declare function estimateMessages(messages: readonly MessageLike[]): number | undefined;
/** Returns an independent request projection. Planning never mutates source;
 * publication belongs to the host adapter after this function succeeds.
 * Only native compacted markers change, and every protection outranks budget. */
export declare function projectMessages(messages: readonly MessageLike[], options: ProjectionOptions): ProjectionResult;
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