/**
 * Prompt caching — the static/dynamic system-prompt split. The TypeScript port
 * of the Rust reference `smooth-operator-core::conversation::PromptCache`.
 *
 * A system prompt has two halves with very different churn rates: role
 * instructions and tool schemas barely change, while project context
 * (AGENTS.md / CLAUDE.md, the working set) changes every turn. Anthropic's
 * prompt cache keys on a PREFIX, so putting the volatile half first invalidates
 * the whole thing. {@link PROMPT_CACHE_BOUNDARY} splits them: everything above
 * the marker is static and hashed once for cache-key dedup, everything below is
 * dynamic and can be swapped without busting the static prefix.
 *
 * Feed the result to the agent as its instructions:
 *
 * ```ts
 * const cache = new PromptCache(`${rules}${PROMPT_CACHE_BOUNDARY}${projectContext}`);
 * new SmoothAgent(provider, { instructions: cache.fullPrompt() });
 * ```
 */
/**
 * Marker that splits a system prompt into a cacheable static portion and a
 * frequently-changing dynamic portion.
 */
export declare const PROMPT_CACHE_BOUNDARY = "__PROMPT_CACHE_BOUNDARY__";
/** A system prompt split at {@link PROMPT_CACHE_BOUNDARY}. */
export declare class PromptCache {
    /** The cacheable half (above the marker). */
    readonly staticPortion: string;
    /** The frequently-changing half (below the marker). */
    dynamicPortion: string;
    private readonly _staticHash;
    private readonly _staticTokens;
    /**
     * Split a system prompt at the boundary marker. With no marker the entire
     * prompt is treated as dynamic — nothing is claimed cacheable that the
     * caller didn't mark.
     */
    constructor(prompt: string);
    /**
     * Reassemble static + boundary + dynamic. With no static portion the dynamic
     * half is returned alone, so a prompt that was never split round-trips
     * unchanged rather than gaining a stray marker.
     */
    fullPrompt(): string;
    /**
     * Swap the dynamic half, leaving the static half and its hash untouched —
     * the whole point of the split.
     */
    updateDynamic(dynamic: string): void;
    /**
     * Identifies the static portion for cache-key deduplication.
     *
     * Process-local only: it is compared against other hashes from THIS engine,
     * never sent on the wire, so it deliberately does not match the Rust
     * reference's value (Rust uses `DefaultHasher`, which is not reproducible
     * across languages — or even across Rust releases). The ported contract is
     * the behavior: same static text hashes the same, different static text
     * hashes differently, and `updateDynamic` never changes it.
     */
    staticHash(): string;
    /** Estimated tokens the static portion saves on a cache hit. */
    cachedTokens(): number;
}
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