feat(core): add event bus integration for automatic metrics

Phase 1.4: Event-driven metrics persistence
- Updated IndexUpdatedEvent to include DetailedIndexStats & isIncremental flag
- Added optional eventBus parameter to RepositoryIndexer constructor
- Emit index.updated events after index() and update() complete
- Fire-and-forget pattern (waitForHandlers: false) to avoid blocking
- Fixed event bus test to include required stats field

Event payload includes:
- type: 'code' | 'github'
- documentsCount, duration, path
- stats: Full DetailedIndexStats snapshot
- isIncremental: Whether this was an update vs full index

This enables automatic snapshot recording via MetricsStore listeners.

Next: CLI integration for MetricsStore

Author: prosdev

packages/core/src/events/__tests__/event-bus.test.ts

@@ -3,6 +3,7 @@
  */
 
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { createDetailedIndexStats } from '../../indexer/__tests__/test-factories';
 import { AsyncEventBus, createTypedEventBus } from '../event-bus';
 import type { SystemEventMap } from '../types';
 
@@ -352,11 +353,19 @@ describe('createTypedEventBus', () => {
     const handler = vi.fn();
     bus.on('index.updated', handler);
 
+    const stats = createDetailedIndexStats({
+      filesScanned: 100,
+      documentsIndexed: 100,
+      duration: 1000,
+      repositoryPath: '/test',
+    });
+
     await bus.emit('index.updated', {
       type: 'code',
       documentsCount: 100,
       duration: 1000,
       path: '/test',
+      stats,
     });
     await new Promise((resolve) => setTimeout(resolve, 10));
 
@@ -365,6 +374,7 @@ describe('createTypedEventBus', () => {
       documentsCount: 100,
       duration: 1000,
       path: '/test',
+      stats,
     });
   });
 

packages/core/src/events/types.ts

@@ -5,6 +5,8 @@
  * Designed for Node.js async patterns.
  */
 
+import type { DetailedIndexStats } from '../indexer/types.js';
+
 /**
  * Event handler function type
  * All handlers are async to support non-blocking operations
@@ -141,6 +143,10 @@ export interface IndexUpdatedEvent {
   documentsCount: number;
   duration: number;
   path: string;
+  /** Full statistics snapshot */
+  stats: DetailedIndexStats;
+  /** Whether this was an incremental update (vs full index) */
+  isIncremental?: boolean;
 }
 
 export interface IndexErrorEvent {

packages/core/src/indexer/index.ts

@@ -5,6 +5,7 @@
 import * as crypto from 'node:crypto';
 import * as fs from 'node:fs/promises';
 import * as path from 'node:path';
+import type { EventBus } from '../events/types.js';
 import { scanRepository } from '../scanner';
 import type { Document } from '../scanner/types';
 import { getCurrentSystemResources, getOptimalConcurrency } from '../utils/concurrency';
@@ -40,8 +41,9 @@ export class RepositoryIndexer {
   private readonly config: Required<IndexerConfig>;
   private vectorStorage: VectorStorage;
   private state: IndexerState | null = null;
+  private eventBus?: EventBus;
 
-  constructor(config: IndexerConfig) {
+  constructor(config: IndexerConfig, eventBus?: EventBus) {
     this.config = {
       statePath: path.join(config.repositoryPath, DEFAULT_STATE_PATH),
       embeddingModel: 'Xenova/all-MiniLM-L6-v2',
@@ -57,6 +59,8 @@ export class RepositoryIndexer {
       embeddingModel: this.config.embeddingModel,
       dimension: this.config.embeddingDimension,
     });
+
+    this.eventBus = eventBus;
   }
 
   /**
@@ -271,6 +275,22 @@ export class RepositoryIndexer {
         this.state.lastUpdate = endTime;
       }
 
+      // Emit index.updated event (fire-and-forget)
+      if (this.eventBus) {
+        void this.eventBus.emit(
+          'index.updated',
+          {
+            type: 'code',
+            documentsCount: documentsIndexed,
+            duration: stats.duration,
+            path: this.config.repositoryPath,
+            stats,
+            isIncremental: false,
+          },
+          { waitForHandlers: false }
+        );
+      }
+
       return stats;
     } catch (error) {
       errors.push({
@@ -410,7 +430,7 @@ export class RepositoryIndexer {
     const warning = this.getStatsWarning(incrementalUpdatesSince);
 
     // Return incremental stats (what changed) with metadata
-    return {
+    const stats: DetailedIndexStats = {
       filesScanned: filesToReindex.length,
       documentsExtracted,
       documentsIndexed,
@@ -431,6 +451,24 @@ export class RepositoryIndexer {
         warning,
       },
     };
+
+    // Emit index.updated event (fire-and-forget)
+    if (this.eventBus) {
+      void this.eventBus.emit(
+        'index.updated',
+        {
+          type: 'code',
+          documentsCount: documentsIndexed,
+          duration: stats.duration,
+          path: this.config.repositoryPath,
+          stats,
+          isIncremental: true,
+        },
+        { waitForHandlers: false }
+      );
+    }
+
+    return stats;
   }
 
   /**