diff --git a/backend/internal/auth/middleware.go b/backend/internal/auth/middleware.go
index a932240..c563f6d 100644
--- a/backend/internal/auth/middleware.go
+++ b/backend/internal/auth/middleware.go
@@ -5,6 +5,8 @@ import (
 	"strings"
 
 	"github.com/gin-gonic/gin"
+
+	"github.com/hhs/camtalk/internal/trace"
 )
 
 // contextKey 用于在 Gin context 中存储 Claims 的 key。
@@ -17,8 +19,13 @@ const (
 // 校验成功后将 user_id 和 username 写入 Gin Context。
 func AuthMiddleware(tokenMgr *TokenManager) gin.HandlerFunc {
 	return func(c *gin.Context) {
+		log := trace.FromContext(c.Request.Context())
 		authHeader := c.GetHeader("Authorization")
 		if authHeader == "" {
+			log.Warnw("auth rejected",
+				"client_ip", c.ClientIP(),
+				"path", c.Request.URL.Path,
+				"reason", "missing authorization header")
 			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{
 				"code":    "INVALID_TOKEN",
 				"message": "missing authorization header",
@@ -29,6 +36,10 @@ func AuthMiddleware(tokenMgr *TokenManager) gin.HandlerFunc {
 		// 提取 Bearer token
 		parts := strings.SplitN(authHeader, " ", 2)
 		if len(parts) != 2 || !strings.EqualFold(parts[0], "Bearer") {
+			log.Warnw("auth rejected",
+				"client_ip", c.ClientIP(),
+				"path", c.Request.URL.Path,
+				"reason", "invalid authorization format")
 			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{
 				"code":    "INVALID_TOKEN",
 				"message": "invalid authorization format",
@@ -38,6 +49,11 @@ func AuthMiddleware(tokenMgr *TokenManager) gin.HandlerFunc {
 
 		claims, err := tokenMgr.ValidateAccess(parts[1])
 		if err != nil {
+			log.Warnw("auth rejected",
+				"client_ip", c.ClientIP(),
+				"path", c.Request.URL.Path,
+				"reason", "invalid or expired token",
+				"error", err)
 			c.AbortWithStatusJSON(http.StatusUnauthorized, gin.H{
 				"code":    "INVALID_TOKEN",
 				"message": "invalid or expired token",