/**
 * Token-aware conversation compaction (sliding window).
 *
 * Phase-1 sibling of the reference engines' compaction. When a conversation's
 * estimated token count exceeds a budget, drop the oldest non-system messages
 * (keeping the system prompt and most recent turns) so the next model call stays
 * within context. A coarse char/4 token estimate is used.
 *
 * Safety: the kept window never *starts* on a `tool` message (which would orphan
 * a tool result whose preceding `assistant` tool_call was trimmed).
 */
type Message = Record<string, unknown>;
export declare function estimateTokens(message: Message): number;
/**
 * Return `messages` trimmed to roughly `maxTokens`, preserving system messages
 * and the most recent turns. Returns the input unchanged when already within
 * budget or when `maxTokens` is non-positive (disabled).
 */
export declare function compact(messages: Message[], maxTokens: number): Message[];
export {};
//# sourceMappingURL=compaction.d.ts.map