diff --git a/internal/config/site_settings.go b/internal/config/site_settings.go
index 11fd894..f4abbe0 100644
--- a/internal/config/site_settings.go
+++ b/internal/config/site_settings.go
@@ -1,6 +1,7 @@
 package config
 
 import (
+	"log"
 	"strconv"
 	"sync"
 
@@ -73,15 +74,19 @@ func (s *SiteSettings) GetBool(key string, defaultVal bool) bool {
 // Set 写入设置（同步写 DB + 更新内存，使用 UPSERT 兼容首次保存）
 func (s *SiteSettings) Set(key, value string) error {
 	entry := model.SiteSetting{Key: key, Value: value}
-	if err := s.db.Clauses(clause.OnConflict{
+	result := s.db.Clauses(clause.OnConflict{
 		Columns:   []clause.Column{{Name: "key"}},
 		DoUpdates: clause.AssignmentColumns([]string{"value"}),
-	}).Create(&entry).Error; err != nil {
-		return err
+	}).Create(&entry)
+	if result.Error != nil {
+		log.Printf("[SiteSettings] Set FAIL key=%s value=%s err=%v", key, value, result.Error)
+		return result.Error
 	}
 	s.mu.Lock()
+	oldVal, existed := s.data[key]
 	s.data[key] = value
 	s.mu.Unlock()
+	log.Printf("[SiteSettings] Set OK key=%s old=%q new=%q existed=%v rows=%d", key, oldVal, value, existed, result.RowsAffected)
 	return nil
 }
 
diff --git a/internal/controller/admin/site_setting_controller.go b/internal/controller/admin/site_setting_controller.go
index dadb181..0157fb8 100644
--- a/internal/controller/admin/site_setting_controller.go
+++ b/internal/controller/admin/site_setting_controller.go
@@ -1,6 +1,7 @@
 package admin
 
 import (
+	"log"
 	"net/http"
 	"strconv"
 
@@ -87,6 +88,10 @@ func (sc *SiteSettingController) ThemePage(c *gin.Context) {
 func (sc *SiteSettingController) GetSettings(c *gin.Context) {
 	all := sc.settingService.GetSettings()
 	audit := sc.settingService.GetAuditSettings(sc.defaults)
+	log.Printf("[GetSettings] all=%d keys audit=%+v", len(all), audit)
+	if v, ok := all["registration.enabled"]; ok {
+		log.Printf("[GetSettings] registration.enabled=%q", v)
+	}
 	common.Ok(c, gin.H{
 		"all":   all,
 		"audit": audit,