/**
 * Where a reconnecting consumer left off in a session log, and whether the
 * kernel can honour it.
 *
 * The shortfall is a VALUE here, not a sentence in a document. A consumer that
 * asks for everything after seq 400 and silently receives a splice from a
 * different generation of the log is wrong and has no way to find out; a
 * consumer handed `{ status: 'unavailable', reason: 'cursor_ahead' }` re-derives
 * from the log and is right.
 */
import type { SessionLogHead } from '../../store/session-log/index.js';
import type { FencingToken } from './durable.js';
import type { SessionRecord } from './records.js';
/** What a consumer holds when it comes back. */
export interface SessionLogCursor {
    /** The last record `seq` the consumer received. Zero means "from the beginning". */
    readonly sinceSeq: number;
    /**
     * The lease fence (`gen`) of the records the consumer received, when it
     * tracked one. Compared for equality only.
     */
    readonly generation?: FencingToken;
}
/** Why a cursor could not be honoured. */
export type SessionLogReplayRefusal = 
/** The consumer claims to have seen more than the log holds. */
'cursor_ahead'
/** The session has been taken over since; the consumer's position belongs to an older holding. */
 | 'generation_changed'
/** The first record returned is not the one right after the cursor. */
 | 'gap';
/** What came of a cursor. */
export type SessionLogReplay = 
/** The cursor is already at the log's head. Nothing was missed. */
{
    readonly status: 'complete';
}
/** Contiguous from `sinceSeq + 1`, oldest first. */
 | {
    readonly status: 'replayed';
    readonly records: readonly SessionRecord[];
}
/** Nothing is delivered. The consumer re-derives from the log. */
 | {
    readonly status: 'unavailable';
    readonly reason: SessionLogReplayRefusal;
};
/**
 * Decide what a cursor is owed, given the log's head and the records read
 * after `cursor.sinceSeq`.
 *
 * Pure. The generation check runs FIRST: a takeover invalidates the position,
 * so comparing sequences across generations would be arithmetic on two
 * different scales. A `null` head is an empty log.
 */
export declare function resolveSessionLogReplay(cursor: SessionLogCursor, head: SessionLogHead | null, records: readonly SessionRecord[]): SessionLogReplay;
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