rover manager improvements and event bus

server/src/services/eventBus.js

@@ -0,0 +1,55 @@
+const EventEmitter = require('events');
+const logger = require('../globals/logger').child('eventBus');
+
+const eventBus = new EventEmitter();
+
+/**
+ * Publish a structured event onto the server-wide bus.
+ * @param {object} options
+ * @param {string} options.source - Origin module identifier.
+ * @param {string} options.type - Event type name.
+ * @param {any} [options.payload] - Optional event payload.
+ */
+function publishEvent({ source, type, payload = null }) {
+  if (!source) {
+    throw new Error('eventBus.publishEvent requires source');
+  }
+  if (!type) {
+    throw new Error('eventBus.publishEvent requires type');
+  }
+  const event = {
+    source,
+    type,
+    payload,
+    ts: Date.now(),
+  };
+  logger.debug('Publishing event', { source, type });
+  eventBus.emit(type, event);
+  eventBus.emit('*', event);
+}
+
+/**
+ * Subscribe to events of a given type.
+ * @param {string} type
+ * @param {(event: object) => void} handler
+ */
+function subscribe(type, handler) {
+  eventBus.on(type, handler);
+  return () => eventBus.off(type, handler);
+}
+
+/**
+ * Subscribe to all events on the bus.
+ * @param {(event: object) => void} handler
+ */
+function subscribeAll(handler) {
+  eventBus.on('*', handler);
+  return () => eventBus.off('*', handler);
+}
+
+module.exports = {
+  eventBus,
+  publishEvent,
+  subscribe,
+  subscribeAll,
+};