feat(server): memory v2 tests and search_memory tool

apps/server/src/services/memory/__tests__/bm25.test.ts

@@ -0,0 +1,37 @@
+import { describe, it, expect } from 'vitest';
+import { Bm25Ranker } from '../bm25.js';
+
+describe('Bm25Ranker', () => {
+  it('scores documents by term frequency', () => {
+    const ranker = new Bm25Ranker();
+    ranker.fit(['the cat sat on the mat', 'the dog chased the cat', 'the bird flew over the mat']);
+    const results = ranker.rank('cat mat');
+    expect(results.length).toBeGreaterThan(0);
+    expect(results[0]!.score).toBeGreaterThan(0);
+  });
+
+  it('returns empty for no matches', () => {
+    const ranker = new Bm25Ranker();
+    ranker.fit(['aaa bbb', 'ccc ddd']);
+    const results = ranker.rank('zzz');
+    expect(results).toHaveLength(0);
+  });
+
+  it('handles single document corpus', () => {
+    const ranker = new Bm25Ranker();
+    ranker.fit(['only document here']);
+    const results = ranker.rank('document');
+    expect(results).toHaveLength(1);
+  });
+
+  it('ranks relevant docs higher', () => {
+    const ranker = new Bm25Ranker();
+    ranker.fit([
+      'javascript is a programming language',
+      'python is also a programming language',
+      'the weather is nice today',
+    ]);
+    const results = ranker.rank('javascript programming');
+    expect(results[0]!.index).toBe(0);
+  });
+});

apps/server/src/services/memory/__tests__/recall.test.ts

@@ -13,3 +13,15 @@ describe('rankByRelevance', () => {
     expect(result[0].title).toBe('Style');
   });
 });
+
+describe('rankByHybrid', () => {
+  it('falls back to BM25 when embeddings unavailable', async () => {
+    const entries: MemoryEntry[] = [
+      { id: '1', topic: 'project', title: 'Style', content: 'Use two-space indentation', tags: ['style'] },
+      { id: '2', topic: 'project', title: 'Tests', content: 'Use vitest for testing', tags: ['testing'] },
+    ];
+    const { rankByHybrid } = await import('../recall.js');
+    const result = await rankByHybrid('indentation style', entries);
+    expect(result.length).toBeGreaterThan(0);
+  });
+});