The wire format has no attribute-level patch, so an element with an async attribute (attr=@{future} in html!, or Node::element_with_pending_attributes) renders its fallback immediately and gets replaced whole once the attribute resolves. A live skeleton of the element's children tracks resolved holes and preserves marker ids for still-pending ones, so that replacement never re-runs or orphans a nested @{...}/@*{...} hole — only the documented cost (a one-time full DOM remount of the element) is unavoidable. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>