State synchronization via localStorage

• Mechanism: The DM and Player views sync using the browser localStorage API and usehooks-ts useLocalStorage.
• Flow: The DM updates the state, the app writes it to local storage, and a storage event triggers an instant re-render in the Player tab.

Why not WebSockets?

• Local play: Designed for in-room sessions on the same machine.
• Offline support: If the internet drops, combat tracking continues locally.
• Simplicity: No persistent backend connection needed.

Why not BroadcastChannel?

• Persistence: localStorage retains the current state. If you accidentally close the Player tab, it reads the latest state instantly on reload. BroadcastChannel is ephemeral and requires explicit state requests.

Implementation details

• Library: usehooks-ts handles all storage event listeners automatically.
• Data access: The DM view accesses all data. The Player view receives the same payload but strictly filters it, displaying only initiative order, names, active turns, conditions, and timers.