/**
 * Layout store — per-session persistence of entry layout data.
 *
 * Stores a layout snapshot (entry id → row height / char count / term width)
 * in memory during the session and persists it to disk alongside the session
 * data so a resumed session can reconstruct the virtual scroll viewport
 * without mounting every entry just to discover its height.
 *
 * Threading: designed for single-threaded use in the TUI's React render
 * cycle. Disk writes use atomic-write (temp-file + rename) for crash safety.
 * Calls should be batched; writes are debounced (500ms idle after last set).
 */
import type { EntryLayout } from './layout-engine.js';
export interface LayoutStoreOptions {
    /** Directory where the session's layout snapshot is stored. */
    sessionDataDir: string | undefined;
    /** When true, skip all disk I/O (for testing / no-session mode). */
    ephemeral?: boolean;
}
export declare class LayoutStore {
    /** In-memory map: entry id → layout data. */
    private readonly layouts;
    /** Current terminal width used for layout computations. */
    private currentTermWidth;
    /** Session data directory path, or undefined for ephemeral mode. */
    private readonly sessionDataDir;
    /** When true, skip all disk I/O. */
    private readonly ephemeral;
    /** Debounce timer handle for pending disk writes. */
    private debounceTimer;
    /** Pending dirty flag — set when in-memory state diverges from disk. */
    private dirty;
    constructor(options: LayoutStoreOptions);
    /** Set the terminal width used for layout computation. */
    setTermWidth(width: number): void;
    /** Get the current terminal width. */
    get termWidth(): number;
    /** Number of entries tracked. */
    get size(): number;
    /** Get the cached layout for an entry id, or undefined. */
    get(id: number): EntryLayout | undefined;
    /** Get the cached row height for an entry id. Returns fallback if unknown. */
    getRows(id: number): number;
    /**
     * True when every entry id in the set has a measured (non-estimated) layout.
     */
    allMeasured(ids: Iterable<number>): boolean;
    /**
     * Record or update the layout for an entry. Idempotent when both the
     * terminal width and row count are unchanged. Marks the store dirty and
     * schedules a debounced disk write.
     */
    set(id: number, layout: EntryLayout): void;
    /**
     * Batch-set multiple layouts at once. More efficient than calling `set()`
     * in a loop because it only triggers one debounced flush.
     */
    setMany(entries: Iterable<EntryLayout>): void;
    /**
     * Promote a layout from 'estimated' to 'measured' once the real component
     * has been mounted and its actual height is known.
     *
     * Also updates the stored `termWidth` to the current terminal width: after a
     * resize, entries are re-seeded with the new width as estimates, and the
     * post-render measurement pass needs to stamp the actual width so the store
     * is consistent. Without this, a subsequent render sees `stored.termWidth`
     * mismatch the current width and re-seeds estimates, discarding the
     * measurement and corrupting the virtual scroll viewport.
     */
    markMeasured(id: number, actualRows: number, termWidth?: number): void;
    /**
     * Remove entries no longer in the active set (after history retention).
     */
    retain(entryIds: Set<number>): void;
    /** Reset all in-memory state (on /clear). */
    clear(): void;
    /**
     * Load layout data from disk. Returns the number of entries restored, or 0
     * when no data exists or the version has changed (caller should regenerate).
     *
     * Call once at session start, before the first render cycle, so the entry
     * height cache can be seeded with accurate (measured) layouts instead of
     * fallback estimates.
     */
    load(): Promise<number>;
    /**
     * Force an immediate disk write. Normally writes are debounced; call this
     * before session end to ensure the latest layout data is persisted.
     */
    flushNow(): Promise<void>;
    /** Schedule a debounced flush to disk. */
    private scheduleFlush;
    /** Cancel any pending flush. */
    private cancelFlush;
}
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