fix(metrics): sync Prometheus zhiyi_total_memories from LanceDB stats

- Stats handler now updates TotalMemories/TotalEpisodes gauges on each call
- Startup goroutine initializes metrics 1s after boot (waits for Rust sidecar)
- Fixes zhiyi_total_memories showing 0 instead of actual count

go/internal/api/routes/core.go

@@ -9,6 +9,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/xiaoxue/memoryweave/internal/metrics"
 	"github.com/xiaoxue/memoryweave/internal/models"
 	"github.com/xiaoxue/memoryweave/internal/selfoptimize"
 	"github.com/xiaoxue/memoryweave/internal/storage"
@@ -384,6 +385,13 @@ func (a *API) Stats(w http.ResponseWriter, r *http.Request) {
 		respondError(w, 500, "stats failed: "+err.Error())
 		return
 	}
+	// 同步 Prometheus 指标
+	if total, ok := s["total_memories"].(float64); ok {
+		metrics.TotalMemories.Set(total)
+	}
+	if total, ok := s["total_episodes"].(float64); ok {
+		metrics.TotalEpisodes.Set(total)
+	}
 	respond(w, 200, s)
 }
 

go/internal/api/server.go

@@ -76,6 +76,20 @@ func NewServer() http.Handler {
 	}
 	api := routes.NewAPI(ldb, emb, rerank)
 
+	// 启动时初始化 Prometheus 指标
+	go func() {
+		time.Sleep(1 * time.Second) // 等待 Rust sidecar 就绪
+		if stats, err := ldb.Stats(); err == nil {
+			if total, ok := stats["total_memories"].(float64); ok {
+				metrics.TotalMemories.Set(total)
+			}
+			if total, ok := stats["total_episodes"].(float64); ok {
+				metrics.TotalEpisodes.Set(total)
+			}
+			log.Printf("[metrics] 初始化指标: memories=%.0f", stats["total_memories"])
+		}
+	}()
+
 	// 图谱：SQLite (graph_nodes/graph_edges) — 设计要求，非 FileGraph JSON
 	graphPath := os.Getenv("GRAPH_PATH")
 	if graphPath == "" {