diff --git a/backend/internal/models/models.go b/backend/internal/models/models.go
index b07924c..e83680b 100644
--- a/backend/internal/models/models.go
+++ b/backend/internal/models/models.go
@@ -41,6 +41,15 @@ func (p SessionConfigPatch) Apply(cfg *SessionConfig) {
 	}
 }
 
+// User 用户。
+type User struct {
+	ID           string    `json:"id"`
+	Username     string    `json:"username"`
+	PasswordHash string    `json:"-"`
+	CreatedAt    time.Time `json:"created_at"`
+	UpdatedAt    time.Time `json:"updated_at"`
+}
+
 // Message 对话消息。
 type Message struct {
 	Role    string `json:"role"` // "user" | "assistant"