import type { Message, MessagesPage } from '../types/api';
export declare function sameMessageList(left: readonly Message[], right: readonly Message[]): boolean;
/** Total persisted parts a page currently holds. Mirrors the route's partCount. */
export declare function countPageParts(items: readonly Message[]): number;
/**
 * Flattens newest-first pages into one chronological thread with a single
 * entry per message. Pages hold whole turns, so this is a concatenation in
 * page order; ids seen more than once (only possible after a widened refetch
 * of the newest page) are collapsed into one message that keeps the position
 * of its oldest copy and the newest copy's metadata.
 */
export declare function mergeMessagePages(pages: readonly MessagesPage[] | undefined): Message[];
/**
 * Reconciles a refetched newest page against the copy already in the cache.
 * The refetch window is capped, so a page that grew past the cap could
 * otherwise drop parts (or whole messages) that are still loaded and still
 * persisted. Fresh parts win; anything the server no longer returns but the
 * cache still holds is kept, oldest first, so nothing already rendered
 * disappears. Optimistic entries are excluded here and re-appended separately.
 */
export declare function reconcileRefetchedPage(cached: MessagesPage | undefined, fresh: MessagesPage): MessagesPage;
/**
 * Writes a merged, flat thread back into the page shape. A message lives on
 * exactly one page — the page it was loaded from — and carries all of its
 * parts, so this is a bucketed pass with no part-level splitting. Messages the
 * cache has not seen before (optimistic sends, a turn that started streaming
 * after the last fetch) join the newest page.
 *
 * Untouched pages are returned by identity, so an update at the live edge never
 * invalidates the older pages above it.
 *
 * Returns `null` when nothing changed.
 */
export declare function distributeMessagesToPages(pages: readonly MessagesPage[], next: readonly Message[]): MessagesPage[] | null;
//# sourceMappingURL=messagePageMerge.d.ts.map