fix(memory): add bounded hybrid recall

memory-v2-pgvector.test.mjs

@@ -1,7 +1,10 @@
 import assert from 'node:assert/strict';
 import test from 'node:test';
 import { createMemoryV2 } from './memory-v2.mjs';
-import { createPgvectorMemoryBackend } from './memory-v2-pgvector.mjs';
+import {
+  createPgvectorMemoryBackend,
+  pgvectorMemoryBackendInternals,
+} from './memory-v2-pgvector.mjs';
 
 test('pgvector backend is disabled by default and does not query storage', async () => {
   let queried = false;
@@ -85,7 +88,9 @@ test('pgvector backend performs parameterized vector lookup when explicitly enab
 
   assert.equal(queries.length, 1);
   assert.match(queries[0].sql, /FROM memory_embeddings/);
-  assert.deepEqual(queries[0].params, ['user-1', '[0.25,0.5,0.75]', 5]);
+  assert.match(queries[0].sql, /WITH vector_candidates/);
+  assert.match(queries[0].sql, /recent_candidates/);
+  assert.deepEqual(queries[0].params, ['user-1', '[0.25,0.5,0.75]', 50]);
   assert.deepEqual(result.semanticMemories, ['用户关注 Memory V2 的 facade 边界']);
   assert.deepEqual(result.memories, [
     {
@@ -94,10 +99,68 @@ test('pgvector backend performs parameterized vector lookup when explicitly enab
       text: '用户关注 Memory V2 的 facade 边界',
       score: 0.87,
       createdAt: '2026-07-02T00:00:00.000Z',
+      updatedAt: '2026-07-02T00:00:00.000Z',
     },
   ]);
 });
 
+test('pgvector hybrid ranking recovers a recent Chinese memory missed by vector top-k', async () => {
+  const marker = 'MEM-RECALL-NEW';
+  const backend = createPgvectorMemoryBackend({
+    enabled: true,
+    pool: {
+      async query() {
+        return {
+          rows: [
+            {
+              id: 1,
+              content: '用户以前关注贵州旅游攻略',
+              type: 'interest',
+              score: 0.91,
+              created_at: '2026-06-01T00:00:00.000Z',
+              updated_at: '2026-06-01T00:00:00.000Z',
+            },
+            {
+              id: 2,
+              content: `用户的记忆召回灰度测试代号是 ${marker}`,
+              type: 'fact',
+              score: -0.49,
+              created_at: '2026-07-22T00:00:00.000Z',
+              updated_at: '2026-07-22T00:00:00.000Z',
+            },
+            {
+              id: 3,
+              content: '用户偏好简洁回答',
+              type: 'preference',
+              score: 0.3,
+              created_at: '2026-07-21T00:00:00.000Z',
+              updated_at: '2026-07-21T00:00:00.000Z',
+            },
+          ],
+        };
+      },
+    },
+    embedQuery: async () => [0.25, 0.5, 0.75],
+  });
+
+  const result = await backend.resolve({
+    userId: 'user-1',
+    query: '我之前让你记住的记忆召回灰度测试代号是什么？请只回答完整代号。',
+    limit: 3,
+  });
+
+  assert.match(result.memories[0].text, new RegExp(marker));
+});
+
+test('pgvector hybrid ranking keeps vector order when query has no lexical overlap', () => {
+  const ranked = pgvectorMemoryBackendInternals.rankHybridCandidates([
+    { id: 1, content: 'alpha', score: 0.2 },
+    { id: 2, content: 'beta', score: 0.8 },
+  ], '完全无关的中文查询', 2);
+  assert.equal(ranked[0].id, '2');
+  assert.equal(ranked[1].id, '1');
+});
+
 test('pgvector backend validates table names before building SQL', () => {
   assert.throws(
     () => createPgvectorMemoryBackend({ tableName: 'memory_embeddings;DROP TABLE users' }),