fix(management): ensure management.html is available synchronously and improve asset sync handling

go.mod

@@ -22,6 +22,7 @@ require (
 	golang.org/x/crypto v0.45.0
 	golang.org/x/net v0.47.0
 	golang.org/x/oauth2 v0.30.0
+	golang.org/x/sync v0.18.0
 	gopkg.in/natefinch/lumberjack.v2 v2.2.1
 	gopkg.in/yaml.v3 v3.0.1
 )
@@ -69,7 +70,6 @@ require (
 	github.com/twitchyliquid64/golang-asm v0.15.1 // indirect
 	github.com/ugorji/go/codec v1.2.12 // indirect
 	golang.org/x/arch v0.8.0 // indirect
-	golang.org/x/sync v0.18.0 // indirect
 	golang.org/x/sys v0.38.0 // indirect
 	golang.org/x/text v0.31.0 // indirect
 	google.golang.org/protobuf v1.34.1 // indirect

internal/api/server.go

@@ -655,15 +655,18 @@ func (s *Server) serveManagementControlPanel(c *gin.Context) {
 
 	if _, err := os.Stat(filePath); err != nil {
 		if os.IsNotExist(err) {
-			go managementasset.EnsureLatestManagementHTML(context.Background(), managementasset.StaticDir(s.configFilePath), cfg.ProxyURL, cfg.RemoteManagement.PanelGitHubRepository)
+			// Synchronously ensure management.html is available with a detached context.
+			// Control panel bootstrap should not be canceled by client disconnects.
+			if !managementasset.EnsureLatestManagementHTML(context.Background(), managementasset.StaticDir(s.configFilePath), cfg.ProxyURL, cfg.RemoteManagement.PanelGitHubRepository) {
 				c.AbortWithStatus(http.StatusNotFound)
 				return
 			}
-
+		} else {
 			log.WithError(err).Error("failed to stat management control panel asset")
 			c.AbortWithStatus(http.StatusInternalServerError)
 			return
 		}
+	}
 
 	c.File(filePath)
 }

internal/managementasset/updater.go

@@ -21,6 +21,7 @@ import (
 	"github.com/router-for-me/CLIProxyAPI/v6/internal/util"
 	sdkconfig "github.com/router-for-me/CLIProxyAPI/v6/sdk/config"
 	log "github.com/sirupsen/logrus"
+	"golang.org/x/sync/singleflight"
 )
 
 const (
@@ -41,6 +42,7 @@ var (
 	currentConfigPtr    atomic.Pointer[config.Config]
 	schedulerOnce       sync.Once
 	schedulerConfigPath atomic.Value
+	sfGroup             singleflight.Group
 )
 
 // SetCurrentConfig stores the latest configuration snapshot for management asset decisions.
@@ -171,8 +173,8 @@ func FilePath(configFilePath string) string {
 }
 
 // EnsureLatestManagementHTML checks the latest management.html asset and updates the local copy when needed.
-// The function is designed to run in a background goroutine and will never panic.
+// It coalesces concurrent sync attempts and returns whether the asset exists after the sync attempt.
-func EnsureLatestManagementHTML(ctx context.Context, staticDir string, proxyURL string, panelRepository string) {
+func EnsureLatestManagementHTML(ctx context.Context, staticDir string, proxyURL string, panelRepository string) bool {
 	if ctx == nil {
 		ctx = context.Background()
 	}
@@ -180,9 +182,11 @@ func EnsureLatestManagementHTML(ctx context.Context, staticDir string, proxyURL
 	staticDir = strings.TrimSpace(staticDir)
 	if staticDir == "" {
 		log.Debug("management asset sync skipped: empty static directory")
-		return
+		return false
 	}
+	localPath := filepath.Join(staticDir, managementAssetName)
 
+	_, _, _ = sfGroup.Do(localPath, func() (interface{}, error) {
 		lastUpdateCheckMu.Lock()
 		now := time.Now()
 		timeSinceLastAttempt := now.Sub(lastUpdateCheckTime)
@@ -193,12 +197,11 @@ func EnsureLatestManagementHTML(ctx context.Context, staticDir string, proxyURL
 				timeSinceLastAttempt.Round(time.Second),
 				managementSyncMinInterval,
 			)
-		return
+			return nil, nil
 		}
 		lastUpdateCheckTime = now
 		lastUpdateCheckMu.Unlock()
 
-	localPath := filepath.Join(staticDir, managementAssetName)
 		localFileMissing := false
 		if _, errStat := os.Stat(localPath); errStat != nil {
 			if errors.Is(errStat, os.ErrNotExist) {
@@ -210,7 +213,7 @@ func EnsureLatestManagementHTML(ctx context.Context, staticDir string, proxyURL
 
 		if errMkdirAll := os.MkdirAll(staticDir, 0o755); errMkdirAll != nil {
 			log.WithError(errMkdirAll).Warn("failed to prepare static directory for management asset")
-		return
+			return nil, nil
 		}
 
 		releaseURL := resolveReleaseURL(panelRepository)
@@ -229,17 +232,17 @@ func EnsureLatestManagementHTML(ctx context.Context, staticDir string, proxyURL
 			if localFileMissing {
 				log.WithError(err).Warn("failed to fetch latest management release information, trying fallback page")
 				if ensureFallbackManagementHTML(ctx, client, localPath) {
-				return
+					return nil, nil
 				}
-			return
+				return nil, nil
 			}
 			log.WithError(err).Warn("failed to fetch latest management release information")
-		return
+			return nil, nil
 		}
 
 		if remoteHash != "" && localHash != "" && strings.EqualFold(remoteHash, localHash) {
 			log.Debug("management asset is already up to date")
-		return
+			return nil, nil
 		}
 
 		data, downloadedHash, err := downloadAsset(ctx, client, asset.BrowserDownloadURL)
@@ -247,12 +250,12 @@ func EnsureLatestManagementHTML(ctx context.Context, staticDir string, proxyURL
 			if localFileMissing {
 				log.WithError(err).Warn("failed to download management asset, trying fallback page")
 				if ensureFallbackManagementHTML(ctx, client, localPath) {
-				return
+					return nil, nil
 				}
-			return
+				return nil, nil
 			}
 			log.WithError(err).Warn("failed to download management asset")
-		return
+			return nil, nil
 		}
 
 		if remoteHash != "" && !strings.EqualFold(remoteHash, downloadedHash) {
@@ -261,10 +264,15 @@ func EnsureLatestManagementHTML(ctx context.Context, staticDir string, proxyURL
 
 		if err = atomicWriteFile(localPath, data); err != nil {
 			log.WithError(err).Warn("failed to update management asset on disk")
-		return
+			return nil, nil
 		}
 
 		log.Infof("management asset updated successfully (hash=%s)", downloadedHash)
+		return nil, nil
+	})
+
+	_, err := os.Stat(localPath)
+	return err == nil
 }
 
 func ensureFallbackManagementHTML(ctx context.Context, client *http.Client, localPath string) bool {