UseContainerReveal

A headless hover/focus reveal primitive. Gives a container a scoped trigger that reveals (or conceals) content inside it when the container is hovered or receives keyboard focus: the classic "row actions appear on hover" pattern. The reveal is CSS-only: no hover state lives in React and hovering never triggers a re-render. The caller authors no StyleX for the reveal itself; the hook hands out the container and content styles, and a nested container shadows its ancestor, so nested containers never leak hover/focus into one another. Accessible by construction: revealed content is visually hidden at rest with position and opacity (never display:none), so it stays mounted, keeps its place in the tab order, and is announced to assistive technology; it reveals on :focus-within so keyboard users see it when tabbing in, stays visible on touch (never gated behind hover on coarse pointers), and honors prefers-reduced-motion.