New Base func

lib/events/bus.ts

@@ -0,0 +1,71 @@
+import type { CoreEvent, CoreEventType, EventHandler } from './types'
+
+// Internal handler type — loose enough for the Map, but type-safe at the public API
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+type AnyHandler = (payload: any) => Promise<void> | void
+
+/**
+ * In-process event bus.
+ *
+ * - Handlers run concurrently via Promise.allSettled (failing handler never crashes emitter)
+ * - Module-level singleton (persists across requests in same process)
+ * - One-way: core services emit, extensions subscribe
+ */
+class EventBus {
+  private handlers = new Map<string, Set<AnyHandler>>()
+
+  /**
+   * Subscribe to an event type.
+   * Returns an unsubscribe function.
+   */
+  on<T extends CoreEventType>(
+    eventType: T,
+    handler: EventHandler<T>
+  ): () => void {
+    if (!this.handlers.has(eventType)) {
+      this.handlers.set(eventType, new Set())
+    }
+
+    const handlerSet = this.handlers.get(eventType)!
+    handlerSet.add(handler as AnyHandler)
+
+    return () => {
+      handlerSet.delete(handler as AnyHandler)
+      if (handlerSet.size === 0) {
+        this.handlers.delete(eventType)
+      }
+    }
+  }
+
+  /**
+   * Emit an event to all registered handlers.
+   * Uses Promise.allSettled so a failing handler never crashes the emitter.
+   */
+  async emit(event: CoreEvent): Promise<void> {
+    const handlerSet = this.handlers.get(event.type)
+    if (!handlerSet || handlerSet.size === 0) return
+
+    const results = await Promise.allSettled(
+      [...handlerSet].map((handler) => handler(event.payload))
+    )
+
+    for (const result of results) {
+      if (result.status === 'rejected') {
+        console.error(
+          `[EventBus] Handler failed for "${event.type}":`,
+          result.reason
+        )
+      }
+    }
+  }
+
+  /**
+   * Remove all handlers (useful for testing).
+   */
+  clear(): void {
+    this.handlers.clear()
+  }
+}
+
+/** Module-level singleton */
+export const eventBus = new EventBus()