/**
 * Cut point detection for compaction.
 *
 * Pure functions for finding valid compaction cut points and turn boundaries.
 */
import type { SessionEntry } from "../session-manager.js";
/**
 * Find the user message (or bashExecution) that starts the turn containing the given entry index.
 * Returns -1 if no turn start found before the index.
 * BashExecutionMessage is treated like a user message for turn boundaries.
 */
export declare function findTurnStartIndex(entries: SessionEntry[], entryIndex: number, startIndex: number): number;
export interface CutPointResult {
    /** Index of first entry to keep */
    firstKeptEntryIndex: number;
    /** Index of user message that starts the turn being split, or -1 if not splitting */
    turnStartIndex: number;
    /** Whether this cut splits a turn (cut point is not a user message) */
    isSplitTurn: boolean;
}
export interface FindCutPointOptions {
    /**
     * Explicit phase-boundary compaction should prefer the newest safe boundary
     * over retaining a large just-finished turn as the recent raw suffix.
     */
    phaseBoundary?: boolean;
    /**
     * When provided, use this entry id as a fixed cut point instead of walking
     * backwards from the newest entry. This lets request-time adapters freeze a
     * previously-computed cut without regenerating the summary.
     */
    anchorEntryId?: string;
    /**
     * When true, ensure the most recent user message is never folded into the
     * compaction summary — the cut point is pulled back to (or before) the
     * latest user message so it survives verbatim. This protects the current
     * task/brief from being reduced to a truncated excerpt mid-run.
     */
    pinLatestUserMessage?: boolean;
}
/**
 * Find the cut point in session entries that keeps approximately `keepRecentTokens`.
 *
 * Algorithm: Walk backwards from newest, accumulating estimated message sizes.
 * Stop when we've accumulated >= keepRecentTokens. Cut at that point.
 *
 * Can cut at user OR assistant messages (never tool results). When cutting at an
 * assistant message with tool calls, its tool results come after and will be kept.
 *
 * Returns CutPointResult with:
 * - firstKeptEntryIndex: the entry index to start keeping from
 * - turnStartIndex: if cutting mid-turn, the user message that started that turn
 * - isSplitTurn: whether we're cutting in the middle of a turn
 *
 * Only considers entries between `startIndex` and `endIndex` (exclusive).
 */
export declare function findCutPoint(entries: SessionEntry[], startIndex: number, endIndex: number, keepRecentTokens: number, options?: FindCutPointOptions): CutPointResult;
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