diff --git a/backend/internal/api/auth.go b/backend/internal/api/auth.go
index 3404d58..f7add06 100644
--- a/backend/internal/api/auth.go
+++ b/backend/internal/api/auth.go
@@ -9,6 +9,7 @@ import (
 	"github.com/hhs/camtalk/internal/auth"
 	apperr "github.com/hhs/camtalk/internal/errors"
 	"github.com/hhs/camtalk/internal/ratelimit"
+	"github.com/hhs/camtalk/internal/trace"
 )
 
 // AuthHandler 提供认证相关的 REST 端点。
@@ -53,6 +54,9 @@ func (h *AuthHandler) RegisterRoutes(rg *gin.RouterGroup, limiter ratelimit.Limi
 
 // Register POST /api/auth/register — 用户注册。
 func (h *AuthHandler) Register(c *gin.Context) {
+	log := trace.FromContext(c.Request.Context())
+	clientIP := c.ClientIP()
+
 	var req auth.RegisterRequest
 	if err := c.ShouldBindJSON(&req); err != nil {
 		c.JSON(http.StatusBadRequest, gin.H{
@@ -72,15 +76,25 @@ func (h *AuthHandler) Register(c *gin.Context) {
 
 	resp, err := h.authService.Register(c.Request.Context(), req)
 	if err != nil {
+		log.Warnw("register failed",
+			"username", req.Username,
+			"client_ip", clientIP,
+			"error", err)
 		handleAuthError(c, err)
 		return
 	}
 
+	log.Infow("register success",
+		"username", req.Username,
+		"client_ip", clientIP)
 	c.JSON(http.StatusCreated, resp)
 }
 
 // Login POST /api/auth/login — 用户登录。
 func (h *AuthHandler) Login(c *gin.Context) {
+	log := trace.FromContext(c.Request.Context())
+	clientIP := c.ClientIP()
+
 	var req auth.LoginRequest
 	if err := c.ShouldBindJSON(&req); err != nil {
 		c.JSON(http.StatusBadRequest, gin.H{
@@ -100,15 +114,24 @@ func (h *AuthHandler) Login(c *gin.Context) {
 
 	resp, err := h.authService.Login(c.Request.Context(), req)
 	if err != nil {
+		log.Warnw("login failed",
+			"username", req.Username,
+			"client_ip", clientIP,
+			"error", err)
 		handleAuthError(c, err)
 		return
 	}
 
+	log.Infow("login success",
+		"username", req.Username,
+		"client_ip", clientIP)
 	c.JSON(http.StatusOK, resp)
 }
 
 // Refresh POST /api/auth/refresh — 刷新令牌。
 func (h *AuthHandler) Refresh(c *gin.Context) {
+	log := trace.FromContext(c.Request.Context())
+
 	var req auth.RefreshRequest
 	if err := c.ShouldBindJSON(&req); err != nil {
 		c.JSON(http.StatusBadRequest, gin.H{
@@ -128,15 +151,21 @@ func (h *AuthHandler) Refresh(c *gin.Context) {
 
 	resp, err := h.authService.Refresh(c.Request.Context(), req)
 	if err != nil {
+		log.Warnw("token refresh failed",
+			"client_ip", c.ClientIP(),
+			"error", err)
 		handleAuthError(c, err)
 		return
 	}
 
+	log.Infow("token refresh success",
+		"client_ip", c.ClientIP())
 	c.JSON(http.StatusOK, resp)
 }
 
 // Logout POST /api/auth/logout — 登出（需要认证）。
 func (h *AuthHandler) Logout(c *gin.Context) {
+	log := trace.FromContext(c.Request.Context())
 	userID := c.GetString(auth.ContextKeyUserID)
 
 	var req struct {
@@ -159,6 +188,9 @@ func (h *AuthHandler) Logout(c *gin.Context) {
 	}
 
 	if err := h.authService.Logout(c.Request.Context(), userID, req.RefreshToken); err != nil {
+		log.Errorw("logout failed",
+			"user_id", userID,
+			"error", err)
 		c.JSON(http.StatusInternalServerError, gin.H{
 			"code":    apperr.CodeInternalError,
 			"message": "failed to logout",
@@ -166,6 +198,8 @@ func (h *AuthHandler) Logout(c *gin.Context) {
 		return
 	}
 
+	log.Infow("logout success",
+		"user_id", userID)
 	c.JSON(http.StatusOK, gin.H{
 		"message": "logged out successfully",
 	})