/**
 * Provider-neutral agent-loop reclaim policy.
 *
 * Every native provider loop grows its own history as the model calls tools,
 * and every one of them can overflow the model's window mid-turn. The policy
 * for reclaiming that budget is identical regardless of message shape:
 *
 *   Stage 1 — shrink old tool outputs to head/tail previews.
 *   Stage 2 — drop the oldest complete tool batches, as units, when previews
 *             are not enough (or when outputs are already small enough that
 *             truncation buys nothing).
 *
 * What differs per provider is only the message SHAPE. So this module owns the
 * decision and adapters own the mechanics: map your history onto
 * `LoopGuardEntry[]`, call `planLoopGuardReclaim`, apply the returned indices.
 *
 * Two invariants the policy never violates:
 *   - entry 0 (the task) is never touched
 *   - a tool batch is dropped whole or not at all, so a `tool_call` never
 *     loses its `tool_result` (providers hard-reject the orphan)
 */
import type { LoopGuardEntry, LoopGuardPlan, LoopGuardPolicy } from "../types/index.js";
/**
 * Fraction of the window the guard reclaims DOWN TO once it fires.
 *
 * The threshold decides *when*; this decides *how far*. Reclaiming only back to
 * the threshold means the next step — which appends an assistant turn plus its
 * tool results — crosses it again, so the guard rewrites the oldest messages on
 * every single step. That mutation invalidates the provider's cached prompt
 * prefix each time. One deeper reclaim every N steps saves the same tokens and
 * leaves the prefix stable in between.
 */
export declare const DEFAULT_LOOP_GUARD_LOW_WATER_RATIO = 0.6;
/** Newest entries the guard never modifies. */
export declare const DEFAULT_LOOP_GUARD_PROTECTED_TAIL = 4;
/**
 * Decide what to reclaim, if anything.
 *
 * Returns `fire: false` when the projected request is within threshold — the
 * caller must then leave its history completely untouched, so a loop that fits
 * never pays a cache invalidation.
 */
export declare function planLoopGuardReclaim(entries: readonly LoopGuardEntry[], policy: LoopGuardPolicy): LoopGuardPlan;