# CURSOR_CONTRACT (v1, frozen) Cursor is client-owned coordination state over server-rendered, identity-bearing children. It is the one place JavaScript owns interaction state; everything else is delegated or observed. ## Contract A conforming Cursor MUST: 1. **Use `aria-activedescendant` as the primary strategy.** Focus stays on a persistent input or container; the active option is referenced by logical id. 2. **Not use roving tabindex as the default.** A focused non-form element is blurred to `` when a LiveView patch touches its subtree — LiveView's focus preservation covers form inputs only. Roving tabindex is therefore not patch-safe and MUST NOT be the default strategy. (It may be offered only where the item set is known never to be server-patched while focused — a narrow case.) 3. **Keep the active descendant pointed at a live node, or collapse deterministically.** After any result/child change, `aria-activedescendant` must either reference an existing node or be cleared by a documented, deterministic policy. It MUST NEVER reference a removed or stale node. 4. **Never re-assert focus on every patch.** Re-focusing the active item in `updated()` is the focus-stealing anti-pattern; it is forbidden. This is *why* the aria-activedescendant model is mandated — it needs no per-patch focus assertion. ## Focus handoff (cross-browser) — allowed vs forbidden The `aria-activedescendant` model requires the keyboard target (the input or the trigger/container the hook listens on) to **hold focus**, or the arrow/Enter keydowns never arrive. **WebKit does not move focus to a `