import type { Message } from '../session/session-jsonl.js';
export interface PromptPrefixStabilityIssue {
    kind: 'shorter' | 'changed' | 'role_changed' | 'content_modified';
    previousLength: number;
    currentLength: number;
    firstChangedIndex?: number;
    detail?: string;
}
export interface PromptCacheEligibility {
    eligible: boolean;
    reason: 'disabled' | 'missing_stable_prefix' | 'stable_prefix_too_short' | 'dynamic_suffix_too_large' | 'eligible';
    stableChars: number;
    dynamicChars: number;
    minStableChars: number;
    maxDynamicCharsRatio: number;
}
export interface PromptCacheEligibilityOptions {
    enabled?: boolean;
    minStableChars?: number;
    maxDynamicCharsRatio?: number;
}
export declare const DEFAULT_PROMPT_CACHE_MIN_STABLE_CHARS = 2048;
export declare const DEFAULT_PROMPT_CACHE_MAX_DYNAMIC_CHARS_RATIO = 0.25;
export declare function isPromptPrefixDebugEnabled(): boolean;
export declare function assessPromptCacheEligibility(parts: {
    stable?: string;
    dynamic?: string;
} | undefined, options?: PromptCacheEligibilityOptions): PromptCacheEligibility;
export declare function snapshotMessagesForPrefixCheck(messages: readonly Message[]): Message[];
export declare function checkPromptPrefixStable(previous: readonly Message[] | null, current: readonly Message[]): PromptPrefixStabilityIssue | null;
export declare function checkToolOrderConsistency(previousToolNames: readonly string[] | null, currentToolNames: readonly string[]): {
    consistent: boolean;
    detail?: string;
};
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