fix(playground): resolve auto group model listing (#6163)

* fix(playground): resolve auto group model listing

- merge and deduplicate available models in configured auto group order.
- reuse special usable group rules and add model filtering regression coverage.

* refactor: extract GetGroupsEnabledModels to dedupe group model expansion

controller/user.go

@@ -647,38 +647,26 @@ func GetUserModels(c *gin.Context) {
 	}
 	groups := service.GetUserUsableGroups(user.Group)
 	group := c.Query("group")
-	if group != "" {
-		if _, ok := groups[group]; !ok {
-			c.JSON(http.StatusOK, gin.H{
-				"success": true,
-				"message": "",
-				"data":    []string{},
-			})
-			return
+	var groupsToQuery []string
+	switch {
+	case group == "":
+		for g := range groups {
+			groupsToQuery = append(groupsToQuery, g)
 		}
-
-		c.JSON(http.StatusOK, gin.H{
-			"success": true,
-			"message": "",
-			"data":    model.GetGroupEnabledModels(group),
-		})
-		return
-	}
-
-	var models []string
-	for group := range groups {
-		for _, g := range model.GetGroupEnabledModels(group) {
-			if !common.StringsContains(models, g) {
-				models = append(models, g)
-			}
+	case group == "auto":
+		if _, ok := groups[group]; ok {
+			groupsToQuery = service.GetUserAutoGroup(user.Group)
+		}
+	default:
+		if _, ok := groups[group]; ok {
+			groupsToQuery = []string{group}
 		}
 	}
 	c.JSON(http.StatusOK, gin.H{
 		"success": true,
 		"message": "",
-		"data":    models,
+		"data":    service.GetGroupsEnabledModels(groupsToQuery),
 	})
-	return
 }
 
 func UpdateUser(c *gin.Context) {