/**
 * Context providing a DOM mount point into which a TimeframeRow's sticky
 * HeaderNameCell can be portaled so it paints above every other cell in
 * the tree (including other rows' sticky name cells).
 *
 * Why this is needed:
 *
 * StickyHeaderContainer uses `position: sticky` which unavoidably creates
 * a stacking context. That traps the TimeframeRow's HeaderNameCell inside
 * the sticky-header layer; its z-index becomes local and cannot compete
 * with z-indexes on sibling elements outside the sticky header (for
 * example, `SectionRow`'s sticky name cell at z:10).
 *
 * To satisfy the desired painting order:
 *
 *     TimeframeRow name  >  other-row name  >  TimeframeRow right section
 *                                             >  other-row right section
 *
 * we render an overlay twin of the HeaderNameCell into the mount exposed
 * by this context. The mount itself lives as a sibling of the virtualized
 * rows (inside `StickyInnerElement`) at a z-index above every other cell,
 * so the overlay paints on top of everything. The original HeaderNameCell
 * stays rendered inline for layout stability.
 *
 * Consumers that receive `null` (for example, tests or Storybook mounts
 * without the tree shell) simply skip the overlay.
 */
export declare const TimeframeNamePortalContext: import('react').Context<HTMLDivElement | null>;