/**
 * Layout decision for the thread quick-jump navigator rail.
 *
 * The rail is absolutely positioned at the far-left edge of the thread. In
 * roomy layouts it renders dock-style magnifying bars plus a large hover
 * preview card. In constrained thread/mobile widths those would overlap the
 * message content, so the rail collapses to a compact strip of dots/ticks and
 * uses a narrower hover preview card.
 *
 * Full-width content additionally gets modest symmetric horizontal spacing on
 * the message rows (see MessageThread) so the left rail/timeline and the right
 * edge both have breathing room; the rail itself always stays on the left.
 */
export interface ThreadNavigatorLayout {
    /** Whether the rail should render in its compact (dots/ticks) form. */
    compact: boolean;
    /** Total interactive width reserved for the rail, in px. */
    railWidth: number;
    /** Minimum marker width (px). */
    barMinWidth: number;
    /** Maximum marker width on hover magnification (px). */
    barMaxWidth: number;
    /** Whether the large hover preview card may be shown. */
    showPreviewCard: boolean;
}
/**
 * Thread widths below this (px) are treated as constrained. Mirrors the
 * `< 640` breakpoint already used for compact thread density so the rail and
 * the message rows switch modes together.
 */
export declare const RAIL_COMPACT_MAX_WIDTH = 640;
/** Interactive rail width (px) in the roomy layout. */
export declare const ROOMY_RAIL_WIDTH = 15;
/** Interactive rail width (px) in the compact (dots/ticks) layout. */
export declare const COMPACT_RAIL_WIDTH = 7;
/** Default vertical slot height (px) for each navigator marker. */
export declare const DEFAULT_NAVIGATOR_ROW_HEIGHT = 14;
/**
 * Resolve the vertical slot height for each navigator marker.
 *
 * @param turnCount - Number of rendered navigator markers.
 * @param availableHeight - Measured vertical space available to the rail.
 */
export declare function getThreadNavigatorRowHeight(turnCount: number, availableHeight: number): number;
/**
 * Resolve the navigator rail layout for a given measured thread width.
 *
 * A width of `0` means the container has not been measured yet; in that case
 * the roomy layout is assumed to avoid a flash of the compact rail on mount.
 *
 * @param threadWidth - Measured thread width in px (0 until first measure).
 */
export declare function getThreadNavigatorLayout(threadWidth: number): ThreadNavigatorLayout;
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