/**
 * tokenBudget — compaction's trigger discipline, without the summarizer.
 *
 * Pattern: WindowStrategy implementation. Its own module, registering
 *          nothing at import.
 * Role:    core/ layer.
 * Emits:   N/A — the stage emits, records and costs; this file decides.
 *
 * The market's other familiar policy: cap the window at a token budget
 * (Mastra's `TokenLimiter` is the closest sibling). What is different here is
 * the same thing that is different about compaction — the number is COUNTED,
 * never guessed:
 *
 *   • the trigger reads the input tokens the PROVIDER reported for the last
 *     call, not a character estimate and not a divide-by-four heuristic;
 *   • a provider that reports no usage gets `CompactionUnmeasurableError` by
 *     name, the same refusal `.compaction()` makes, rather than an invented
 *     window size or a configured budget that silently never applies.
 *
 * When over budget it drops the oldest contiguous removable span — the same
 * span compaction would have folded, chosen by the same refusal engine — and
 * writes no summary at all. Nothing is claimed about what left, because
 * nothing was read: the record and the eviction events name it, and the
 * commit log still has it verbatim.
 *
 * Use it over `summarizeOldest` when you would rather lose the old turns than
 * pay a summarizer to paraphrase them, and over `slidingWindow` when the
 * thing you are actually defending is a token bill rather than a turn depth.
 */
import type { WindowStrategy } from '../strategy.js';
import type { TokenBudgetOptions } from '../types.js';
/** `WindowRecord.strategy` written by every record this strategy files. */
export declare const TOKEN_BUDGET = "token-budget";
/**
 * Drop the oldest turns whenever the last call's adapter-reported input
 * tokens exceed `thresholdTokens`.
 *
 * @example
 * ```ts
 * import { Agent, tokenBudget } from 'agentfootprint';
 *
 * const agent = Agent.create({ provider: anthropic(), model: 'claude-sonnet-4-5' })
 *   .window(tokenBudget({ thresholdTokens: 120_000 }))
 *   .build();
 * ```
 */
export declare function tokenBudget(options: TokenBudgetOptions): WindowStrategy;