// Cross-window session-list sync. Each desktop window is its own renderer
// process with its own gateway socket and session store, so a mutation in one
// (e.g. a new chat started in the compact pop-out) never reaches another
// window. This bus pings every window to re-pull the shared session list; the
// data already lives in the backend, the other window just doesn't know to look.
const CHANNEL = 'hermes:sessions'

const channel = typeof BroadcastChannel === 'undefined' ? null : new BroadcastChannel(CHANNEL)

// A window that mutated the session list (created / titled a chat) tells the
// others to refresh. A BroadcastChannel never delivers to its own poster, so the
// caller refreshes locally as it already does.
export function broadcastSessionsChanged(): void {
  channel?.postMessage(1)
}

export function onSessionsChanged(handler: () => void): () => void {
  if (!channel) {
    return () => {}
  }

  channel.addEventListener('message', handler)

  return () => channel.removeEventListener('message', handler)
}