import type { Usage } from "../types.js";
export type CacheLayer = "tools" | "system" | "project" | "messages";
export declare const CACHE_LAYER_ORDER: readonly CacheLayer[];
export type CacheRetention = "long" | "short" | "none";
export interface LayerBlock {
    layer: CacheLayer;
    /** Canonical UTF-8 bytes that form the layer's stable prefix. */
    bytes: string;
    /** At most one breakpoint per layer on breakpoint-capable providers. */
    breakpoint?: boolean;
}
export interface CachePolicy {
    retention: CacheRetention;
    /** If true, the provider supports explicit breakpoints (Anthropic-style). */
    supportsBreakpoints: boolean;
}
export interface LayeredPayload {
    layers: LayerBlock[];
    policy: CachePolicy;
}
export declare function defaultPolicy(): CachePolicy;
export interface CacheUsageReport {
    cachedInputTokens: number;
    cacheWriteTokens: number;
    uncachedInputTokens: number;
}
export declare function totalInputTokens(u: CacheUsageReport): number;
export interface RetentionResolveContext {
    roleDefault: CacheRetention;
    /** CLI flag --cache=long|short|none overrides role default. */
    cliFlag?: CacheRetention;
    /** CaveKit phase override takes precedence over role default but
     *  is still overridden by an explicit CLI flag. */
    cavekitPhaseOverride?: CacheRetention;
}
export declare function resolveRetention(ctx: RetentionResolveContext): CacheRetention;
/** Enforce R1: at most one breakpoint per layer, layers in canonical order. */
export declare function validateLayers(layers: LayerBlock[]): void;
export declare function usageToCacheReport(usage: Usage): CacheUsageReport;
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