/**
 * cache-first — Immutable prefix + append-only log for DeepSeek prefix-cache stability.
 *
 * Harvested from reasonix Pillar 1 (Cache-First Loop).
 *
 * DeepSeek's automatic prefix caching activates only when the exact byte prefix
 * of the previous request matches. Most agent loops reorder, rewrite, or inject
 * fresh timestamps each turn — cache hit rate in practice: <20%.
 *
 * This module tracks the system prefix and ensures messages are serialized in
 * append-only order so the prefix stays byte-stable across turns.
 */
import type { DeepSeekChatMessage } from "./types.js";
/**
 * Compute a stable hash for a value using a fast non-crypto algorithm.
 * DeepSeek's cache is byte-prefix based, so we just need a deterministic
 * fingerprint to detect changes.
 */
export declare function fastHash(value: string): string;
/**
 * Detect whether a provider URL targets DeepSeek.
 */
export declare function isDeepSeekProvider(baseUrl: string): boolean;
/**
 * Immutable prefix tracker.
 *
 * Tracks the prefix derived from the system prompt + tool definitions.
 * These are what determine DeepSeek's prefix-cache matching — the rest of
 * the conversation history just appends after the stable prefix.
 *
 * Message truncation (context window compaction) does NOT affect prefix
 * stability, because the prefix hash only considers:
 *   1. The system message content
 *   2. The tool-call definitions (assistant messages with tool_calls)
 *
 * If neither changes across turns, the prefix is "stable" and DeepSeek's
 * automatic disk cache will hit on every repeat of the same prefix bytes.
 */
export declare class PrefixGuard {
    private _systemHash;
    private _toolsHash;
    private _prevPrefixHash;
    private _prefixHash;
    private _stabiliseCount;
    /** Stabilise messages array: system first, stable prefix hash. */
    stabilise(messages: DeepSeekChatMessage[]): {
        messages: DeepSeekChatMessage[];
        prefixHash: string;
    };
    /** Current prefix hash for cache-diagnostics headers. */
    get prefixHash(): string;
    /**
     * True when the prefix hash is stable across at least 2 successive calls.
     * First call always returns false (no baseline for comparison).
     * Seed calls after reset return false until a second comparison.
     */
    isStable(): boolean;
    /** Whether the guard has been initialized (computed at least once). */
    isInitialized(): boolean;
    /** Times stabilise() has been called since last reset. */
    get callCount(): number;
    /** Reset (new session or context cleared). */
    reset(): void;
}
/**
 * Append-only log tracker.
 *
 * Ensures that conversation history is only ever appended, never mutated or
 * reordered. This preserves the prefix for subsequent turns.
 */
export declare class AppendOnlyLog {
    private _entryCount;
    /** Validate that the messages log has only grown (no deletions / reorders). */
    validate(entries: DeepSeekChatMessage[]): boolean;
    reset(): void;
}