function mountViewer() { const unsub = eventBus.subscribe('mode-change', handler); onUnmount(() => unsub()); } Versioned async operations:

This treatise explains and prescribes handling the “viewerframe mode refresh hot” problem — an issue that appears when an app’s viewer frame (the UI component that displays content) needs to update its mode quickly and reliably, especially under hot-reload or fast-refresh conditions. It covers root causes, design patterns, concrete implementations, troubleshooting, and practical tips for robust behavior.

let currentInitId = null;

const setModeDebounced = debounce((m) => setMode(m), 150); Unique instance IDs:

// atomically set mode in store store.setMode(instanceId, mode);