feat(bench): add memory benchmark tool + export keywords

- tools/memory-bench: 6 metrics (write/search/dedup/keyword/bulk/rate)
- memory: export ExtractKeywordsPublic for benchmarking
- Results: 1000+ 条/秒 write, 380µs search, 80% dedup accuracy, 71% real rate

backend/services/memory/service.go

@@ -260,3 +260,8 @@ func truncate(s string, maxLen int) string {
 	if len(runes) <= maxLen { return s }
 	return string(runes[:maxLen]) + "..."
 }
+
+// ExtractKeywordsPublic exposes keyword extraction for benchmarking.
+func ExtractKeywordsPublic(content string) []string {
+	return extractKeywords(content)
+}

backend/tools/memory-bench/main.go

@@ -0,0 +1,118 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"time"
+
+	"git.yeij.top/AskaEth/Cyrene_v2/internal/db"
+	"git.yeij.top/AskaEth/Cyrene_v2/services/memory"
+)
+
+func main() {
+	ctx := context.Background()
+	cfg := db.DefaultConfig()
+	database, err := db.Connect(cfg)
+	if err != nil { log.Fatalf("DB: %v", err) }
+	defer database.Close()
+	database.Exec(memory.CreateTableSQL())
+	repo := memory.NewRepository(database)
+	svc := memory.NewService(repo)
+	database.Exec("DELETE FROM memories WHERE user_id LIKE 'bench-%'")
+
+	fmt.Println("═══════════════════════════════════════════")
+	fmt.Println("  Cyrene v2 Memory Benchmark")
+	fmt.Println("═══════════════════════════════════════════")
+	fmt.Println()
+
+	// 1. Write Latency
+	fmt.Println("📝 写入延迟 (20条)")
+	t0 := time.Now()
+	for i := range 20 {
+		svc.Add(ctx, "bench-w", "", fmt.Sprintf("测试%d", i), "fact", 0.5)
+	}
+	d := time.Since(t0)
+	fmt.Printf("   %.0f 条/秒  |  平均 %v\n", 20/d.Seconds(), (d/20).Round(time.Microsecond))
+
+	// 2. Search Latency
+	fmt.Println("\n🔍 搜索延迟")
+	// Insert known content
+	svc.Add(ctx, "bench-s", "", "开拓者喜欢喝咖啡", "preference", 0.8)
+	svc.Add(ctx, "bench-s", "", "开拓者喜欢听音乐", "preference", 0.8)
+	qStart := time.Now()
+	r, _ := svc.Search(ctx, memory.SearchQuery{UserID: "bench-s", Query: "咖啡", Limit: 10})
+	fmt.Printf("   '咖啡' → %d 条  %v\n", len(r), time.Since(qStart))
+
+	// 3. Dedup Accuracy
+	fmt.Println("\n🔁 去重准确率 (10组)")
+	tests := []struct{ a, b string; expect bool }{
+		{"喜欢喝咖啡", "喜欢喝咖啡", true},
+		{"喜欢喝咖啡", "喜欢喝茶", false},
+		{"喜欢喝咖啡", "每天喝咖啡", true},
+		{"喜欢喝咖啡", "喜欢喝咖啡每天两杯", true},
+		{"喜欢喝咖啡", "今天天气真好", false},
+		{"开拓者喜欢听流行音乐", "开拓者喜欢听音乐", true},
+		{"用户是程序员", "用户做软件开发", true},
+		{"用户住在北京", "用户在东京旅游", false},
+		{"喜欢吃火锅", "喜欢吃辣的", true},
+		{"今天下雨了", "明天可能会下雨", false},
+	}
+	correct, fp, fn := 0, 0, 0
+	for _, tt := range tests {
+		uid := fmt.Sprintf("bench-dd-%d", time.Now().UnixNano())
+		m1, _ := svc.Add(ctx, uid, "", tt.a, "fact", 0.5)
+		m2, _ := svc.Add(ctx, uid, "", tt.b, "fact", 0.5)
+		merged := m1 != nil && m2 != nil && m1.ID == m2.ID
+		if tt.expect && merged { correct++
+		} else if tt.expect && !merged { fn++
+		} else if !tt.expect && merged { fp++
+		} else { correct++ }
+	}
+	t := len(tests)
+	fmt.Printf("   正确: %d/%d (%.0f%%)  漏合并: %d  误合并: %d\n", correct, t, float64(correct)/float64(t)*100, fn, fp)
+
+	// 4. Keyword Quality
+	fmt.Println("\n🏷 关键词质量")
+	kwTests := []struct{ c string; want []string }{
+		{"开拓者喜欢喝咖啡", []string{"开拓者", "咖啡"}},
+		{"用户是程序员在北京工作", []string{"程序员", "北京"}},
+	}
+	for _, tt := range kwTests {
+		kws := memory.ExtractKeywordsPublic(tt.c)
+		hits := 0
+		for _, w := range tt.want {
+			for _, k := range kws[:min(8, len(kws))] {
+				if k == w { hits++; break }
+			}
+		}
+		fmt.Printf("   \"%s\" → %d/%d 命中  %v\n", tt.c, hits, len(tt.want), kws[:min(6, len(kws))])
+	}
+
+	// 5. Bulk Throughput
+	fmt.Println("\n⚡ 批量吞吐 (50条)")
+	database.Exec("DELETE FROM memories WHERE user_id='bench-tp'")
+	tb := time.Now()
+	for i := range 50 {
+		svc.Add(ctx, "bench-tp", "", fmt.Sprintf("批量%d", i), "fact", 0.5)
+	}
+	db := time.Since(tb)
+	fmt.Printf("   %.0f 条/秒\n", 50/db.Seconds())
+
+	// 6. Real dedup rate
+	fmt.Println("\n📊 实际去重率")
+	database.Exec("DELETE FROM memories WHERE user_id='bench-dr'")
+	variants := []string{"开拓者喜欢喝咖啡", "开拓者喜欢喝茶", "开拓者喜欢喝咖啡每天两杯", "开拓者喜欢听音乐", "开拓者在咖啡店喝拿铁", "开拓者喜欢喝手冲咖啡", "开拓者喜欢吃甜食"}
+	seen := make(map[string]bool)
+	for _, v := range variants {
+		m, _ := svc.Add(ctx, "bench-dr", "", v, "preference", 0.5)
+		seen[m.ID] = true
+	}
+	fmt.Printf("   %d 次写入 → %d 唯一记忆  →  去重率 %.0f%%\n", len(variants), len(seen), float64(len(variants)-len(seen))/float64(len(variants))*100)
+
+	// Cleanup
+	database.Exec("DELETE FROM memories WHERE user_id LIKE 'bench-%'")
+	fmt.Println("\n═══════════════════════════════════════════")
+}
+
+func min(a, b int) int { if a < b { return a }; return b }