/**
 * The item half of the SS4 client fold: upsert-by-revision plus delta
 * accumulation (spec 14990 FR-007, INV-003/INV-004).
 *
 * WHY THIS IS GENERIC. The concrete wire item type (`Item`, `ItemDeltaParams`,
 * …) is rendered by `crates/protocol` and is not yet in the committed
 * declarations — the session-view plane is enrolled by #14953. INV-001
 * forbids hand-writing a protocol type to fill the gap, so this module states
 * only the *algebraic precondition* its rules need — an item has an identity
 * and a revision — and takes the payload as a type parameter. When #14953
 * lands, `SessionFold` binds `T` to `@muse-code/msp`'s `Item` with no change here
 * and no protocol shape ever restated locally.
 */
/** The minimum an upsert needs: identity plus the monotonic ordering guard. */
export interface RevisionedItem {
    readonly itemId: string;
    readonly revision: number;
}
/** What an apply did — enough for a consumer to render without re-diffing. */
export type ItemApplyOutcome = {
    readonly kind: "inserted";
    readonly itemId: string;
} | {
    readonly kind: "replaced";
    readonly itemId: string;
    readonly from: number;
    readonly to: number;
}
/** A stale or replayed re-emission. The store did not change (INV-003). */
 | {
    readonly kind: "ignoredStaleRevision";
    readonly itemId: string;
    readonly held: number;
    readonly offered: number;
};
/** What a delta did. Deltas bump no revision (tdd SS4.4.1). */
export type DeltaApplyOutcome = {
    readonly kind: "appended";
    readonly itemId: string;
    readonly field: string;
    readonly length: number;
}
/**
 * A delta for an item the store does not hold. Deltas are a streaming
 * optimization and are never a fold's only source of a fact (tdd SS4.7.3),
 * so this is buffered against the item's arrival rather than dropped or
 * treated as an error.
 */
 | {
    readonly kind: "bufferedForAbsentItem";
    readonly itemId: string;
    readonly field: string;
};
/** Client-only annotation required when an ephemeral host dies abnormally. */
export interface TerminalUnknownItemAnnotation {
    readonly kind: "terminalUnknown";
    readonly itemId: string;
}
/**
 * Items in first-opened order (the order tdd SS4.9.1 requires of a snapshot),
 * each held at its latest revision, with per-field delta accumulators.
 */
export declare class ItemStore<T extends RevisionedItem> {
    #private;
    /**
     * Apply an `item/started` | `item/updated` | `item/completed` payload.
     * Replace iff the incoming revision is strictly higher (INV-003).
     */
    apply(item: T): ItemApplyOutcome;
    /**
     * Apply an `item/delta`: a UTF-8-safe append to the open item's field named
     * by `field` (default `"text"`), contiguous and lossless in cursor order.
     * The concatenation of all deltas for a field path equals that field's
     * value on the final `item/completed` object (INV-004, tdd SS4.3.1).
     */
    applyDelta(itemId: string, delta: string, field?: string): DeltaApplyOutcome;
    /** The accumulated delta text for a field path, or `undefined` if none. */
    accumulated(itemId: string, field?: string): string | undefined;
    /** Every field path that has accumulated deltas for this item. */
    accumulatedFields(itemId: string): readonly string[];
    get(itemId: string): T | undefined;
    has(itemId: string): boolean;
    /** Items in first-opened order (tdd SS4.9.1). */
    list(): readonly T[];
    /** The id of the most recently opened item, or `undefined` when empty. */
    lastOpenedItemId(): string | undefined;
    get size(): number;
    /**
     * Seed from a snapshot's `state.items` (tdd SS4.9.1): every item at its
     * latest revision at the snapshot cursor, in first-opened order. Seeding
     * REPLACES the store — a snapshot is authoritative (tdd SS4.9), never
     * merged into stale local state.
     *
     * Delta accumulators are intentionally NOT seeded: a snapshot carries
     * streamed fields at their accumulated-so-far values on the item itself,
     * and `view/page` never replays ephemeral-sourced deltas (tdd SS4.7.3).
     */
    seed(items: Iterable<T>): void;
    /**
     * Permanently discard an ephemeral session after abnormal host death.
     *
     * The last wire item remains byte-for-byte intact: terminal-unknown is a
     * client display annotation, never a fabricated `item/completed` or wire
     * status (SS2.13.3b / SS4.4.3). Further events and snapshot seeding are
     * refused because this session has no resume surface.
     */
    markEphemeralHostDeath(isInProgress: (item: T) => boolean): readonly TerminalUnknownItemAnnotation[];
    isTerminalUnknown(itemId: string): boolean;
    get ephemeralSessionDiscarded(): boolean;
}