// Tiny event bus for cross-component state (pending count, agent toggle, etc.).
// No reactive framework — just publish/subscribe with last-value semantics.

const subs = new Map();   // event → Set<fn>
const last = new Map();   // event → last value

export function on(event, fn) {
  if (!subs.has(event)) subs.set(event, new Set());
  subs.get(event).add(fn);
  if (last.has(event)) fn(last.get(event));
  return () => subs.get(event).delete(fn);
}

export function emit(event, value) {
  last.set(event, value);
  const set = subs.get(event);
  if (set) for (const fn of set) fn(value);
}

export function get(event) { return last.get(event); }