/**
 * window/options — validate a window strategy's options ONCE, at build time.
 *
 * Pattern: Guard functions returning a resolved config.
 * Role:    core/ layer. Every message here takes a `label`, because the same
 *          option bag arrives through two doors — `.compaction({...})` and
 *          `summarizeOldest({...})` — and an error should name the door the
 *          caller actually used. One implementation, so the two doors can
 *          never drift into validating differently.
 * Emits:   N/A.
 *
 * Everything fails at `.build()`, never mid-run. A window policy that turns
 * out to be nonsense on iteration 40 of a paid run is a policy that cost you
 * money to discover.
 */
import type { CompactionOptions, CompactionRetention, ResolvedCompaction, SlidingWindowOptions, TokenBudgetOptions } from './types.js';
/** Default depth of the "never touch this" recent window. */
export declare const DEFAULT_KEEP_RECENT_TURNS = 6;
/**
 * How many tools' most recent results the window holds beyond
 * `keepRecentTurns` when nobody said (9.57.0). ON by default, at 2.
 *
 * On by default for the same reason 9.55.0's anchor is: the counterfactual to
 * a pinned 5,800-character tool result is not 5,800 bytes saved, it is a
 * fabricated id, a refusal, a wasted action out of a small budget, and the
 * same 5,800 bytes fetched again. That is a correctness failure the framework
 * caused, and those are fixed on by default.
 *
 * TWO rather than one because the ceiling is spent newest-first among STALE
 * candidates: a one-word acknowledgement from an actuator the model has
 * stopped using can occupy a slot ahead of an older load-bearing observation.
 * Two slots absorb that. `false` or `0` switches the pin off entirely.
 */
export declare const DEFAULT_KEEP_LAST_TOOL_RESULTS = 2;
/**
 * Validate the `keepLastToolResults` dial. Refused at construction, never
 * mid-run — the house rule for every window option.
 */
export declare function requireKeepLastToolResults(value: unknown, label: string): void;
/**
 * What happens to folded messages when nobody said. The originals ride with
 * the conversation: losing them has to be a choice somebody typed, not a
 * default they inherited.
 */
export declare const DEFAULT_RETENTION: CompactionRetention;
/**
 * Validate `.compaction()` / `summarizeOldest()` options.
 *
 * @param label the door being used, so the error names it
 */
export declare function resolveCompactionOptions(options: CompactionOptions, label: string): ResolvedCompaction;
/** Validate `slidingWindow()` options. */
export declare function resolveSlidingWindowOptions(options: SlidingWindowOptions, label: string): {
    readonly keepRecentTurns: number;
};
/** Validate `tokenBudget()` options. */
export declare function resolveTokenBudgetOptions(options: TokenBudgetOptions, label: string): {
    readonly thresholdTokens: number;
    readonly keepRecentTurns: number;
};