Function routeTreeKey

packages/core/src/runtime/router/tree.ts:36–240

(event: ZrevEvent, ctx: TreeRoutingCtx<T>)

 *   - Asterisk (*): Expand all siblings
 */
export function routeTreeKey<T>(event: ZrevEvent, ctx: TreeRoutingCtx<T>): TreeRoutingResult {
  if (event.kind !== "key") return Object.freeze({ consumed: false });
  if (event.action !== "down") return Object.freeze({ consumed: false });
  if (!ctx.keyboardNavigation) return Object.freeze({ consumed: false });

  const { treeId, flatNodes, expanded, state } = ctx;
  const { focusedKey } = state;
  const nodeCount = flatNodes.length;

  if (nodeCount === 0) return Object.freeze({ consumed: false });

  // Find current focused index
  const currentIndex = focusedKey !== null ? findNodeIndex(flatNodes, focusedKey) : -1;
  const currentNode = currentIndex >= 0 ? flatNodes[currentIndex] : undefined;

  // Arrow Up - move to previous visible node
  if (event.key === ZR_KEY_UP) {
    const nextIndex = currentIndex > 0 ? currentIndex - 1 : 0;
    if (nextIndex === currentIndex && currentIndex >= 0) {
      return Object.freeze({ consumed: true });
    }

    const nextNode = flatNodes[nextIndex];
    if (nextNode) {
      return Object.freeze({
        nextFocusedKey: nextNode.key,
        nodeToSelect: nextNode.key,
        consumed: true,
      });
    }
    return Object.freeze({ consumed: true });
  }

  // Arrow Down - move to next visible node
  if (event.key === ZR_KEY_DOWN) {
    const nextIndex = currentIndex < nodeCount - 1 ? currentIndex + 1 : nodeCount - 1;
    if (nextIndex === currentIndex) {
      return Object.freeze({ consumed: true });
    }

    const nextNode = flatNodes[nextIndex];
    if (nextNode) {
      return Object.freeze({
        nextFocusedKey: nextNode.key,
        nodeToSelect: nextNode.key,
        consumed: true,
      });
    }
    return Object.freeze({ consumed: true });
  }

  // Arrow Right - expand or move to first child
  if (event.key === ZR_KEY_RIGHT) {
    if (!currentNode) return Object.freeze({ consumed: true });

    const isExpanded = expanded.includes(currentNode.key);

    if (currentNode.hasChildren) {