fix: 完善Agent系统信息上报

- 持续上报系统元数据并动态更新运行时长
- 兼容旧版心跳补齐资产运行时长
- 修复监控指标当前值重复显示单位

backend/controller/agent.go

@@ -150,6 +150,10 @@ func (h *AgentHandler) ReceiveReport(c *gin.Context) {
 			updates["uptime"] = req.System.Uptime
 		}
 	}
+	// 兼容旧版 Agent：系统信息缺席时使用心跳中的运行时长补齐资产元数据。 // Logan.Li
+	if _, ok := updates["uptime"]; !ok && req.Heartbeat.UptimeSec > 0 {
+		updates["uptime"] = req.Heartbeat.UptimeSec
+	}
 	var result *gorm.DB
 	if assetMatched {
 		result = h.db.Model(&model.Server{}).Where("id = ?", matchedServer.ID).Updates(updates)
@@ -162,19 +166,32 @@ func (h *AgentHandler) ReceiveReport(c *gin.Context) {
 	// 避免 Agent 每次上报（10s）都新建记录导致资产越来越多。
 	if result.Error == nil && result.RowsAffected == 0 {
 		osName := ""
+		kernel := ""
+		uptime := req.Heartbeat.UptimeSec
 		if req.System != nil {
 			osName = req.System.OSVersion
+			kernel = req.System.Kernel
+			if req.System.Uptime > 0 {
+				uptime = req.System.Uptime
+			}
 		}
 		var existing model.Server
 		if h.db.Where("hostname = ?", req.Hostname).Take(&existing).Error == nil {
 			// 已自动注册过 → 仅更新实时指标，不重复创建
-			h.db.Model(&existing).Updates(map[string]interface{}{
+			existingUpdates := map[string]interface{}{
 				"ip": matchIP, "os": osName, "cpu": req.CPU.CoreCount,
 				"memory": memMB, "disk": diskGB, "status": "running",
 				"agent_status": "online", "agent_version": req.AgentVersion,
 				"cpu_usage": req.CPU.UsagePercent, "memory_usage": req.Memory.UsagePercent,
 				"disk_usage": diskAvg,
-			})
+			}
+			if kernel != "" {
+				existingUpdates["kernel"] = kernel
+			}
+			if uptime > 0 {
+				existingUpdates["uptime"] = uptime
+			}
+			h.db.Model(&existing).Updates(existingUpdates)
 		} else {
 			// 真正的新主机 → 注册，hostname 无唯一索引时不使用 OnConflict。 // Logan.Li
 			newServer := model.Server{
@@ -190,6 +207,8 @@ func (h *AgentHandler) ReceiveReport(c *gin.Context) {
 				Status:       "running",
 				AgentStatus:  "online",
 				AgentVersion: req.AgentVersion,
+				Kernel:       kernel,
+				Uptime:       uptime,
 				CPUUsage:     req.CPU.UsagePercent,
 				MemoryUsage:  req.Memory.UsagePercent,
 				DiskUsage:    diskAvg,

backend/controller/agent_report_test.go

@@ -79,6 +79,51 @@ func TestReceiveReportMatchesExistingAssetByIP(t *testing.T) {
 	}
 }
 
+func TestReceiveReportUsesHeartbeatUptimeWithoutSystemPayload(t *testing.T) {
+	gin.SetMode(gin.TestMode)
+	db, err := gorm.Open(sqlite.Open("file:agent_report_heartbeat_uptime?mode=memory&cache=shared"), &gorm.Config{
+		Logger: gormlogger.Default.LogMode(gormlogger.Silent),
+	})
+	if err != nil {
+		t.Fatalf("打开测试数据库失败: %v", err)
+	}
+	if err := db.AutoMigrate(&model.Server{}, &model.AgentReport{}, &model.HealthProbe{}); err != nil {
+		t.Fatalf("迁移测试表失败: %v", err)
+	}
+
+	server := model.Server{Hostname: "c-monitor", IP: "172.19.16.113", Status: "running"}
+	if err := db.Create(&server).Error; err != nil {
+		t.Fatalf("创建测试资产失败: %v", err)
+	}
+
+	body := []byte(`{
+		"hostname":"c-monitor",
+		"ip":"172.19.16.113",
+		"agent_version":"v2.1.0",
+		"cpu":{"usage_percent":1.5,"core_count":4},
+		"memory":{"total_gb":15.1,"used_gb":1.8,"available_gb":13.3,"usage_percent":11.9},
+		"heartbeat":{"uptime_sec":7200}
+	}`)
+	req := httptest.NewRequest(http.MethodPost, "/api/v1/agent/report", bytes.NewReader(body))
+	req.Header.Set("Content-Type", "application/json")
+	recorder := httptest.NewRecorder()
+	c, _ := gin.CreateTestContext(recorder)
+	c.Request = req
+
+	NewAgentHandler(db, nil, nil).ReceiveReport(c)
+	if recorder.Code != http.StatusOK {
+		t.Fatalf("上报返回码 = %d, body=%s", recorder.Code, recorder.Body.String())
+	}
+
+	var gotServer model.Server
+	if err := db.Take(&gotServer, server.ID).Error; err != nil {
+		t.Fatalf("读取资产失败: %v", err)
+	}
+	if gotServer.Uptime != 7200 {
+		t.Fatalf("心跳运行时长未写入资产: got=%d want=7200", gotServer.Uptime)
+	}
+}
+
 func TestGetLatestReportsUsesUTCTimeBoundary(t *testing.T) {
 	gin.SetMode(gin.TestMode)
 	db, err := gorm.Open(sqlite.Open("file:agent_latest_utc?mode=memory&cache=shared"), &gorm.Config{