diff --git a/internal/registry/model_registry.go b/internal/registry/model_registry.go
index f5af06f4..1fb307be 100644
--- a/internal/registry/model_registry.go
+++ b/internal/registry/model_registry.go
@@ -4,6 +4,7 @@
 package registry
 
 import (
+	"fmt"
 	"sort"
 	"strings"
 	"sync"
@@ -800,6 +801,9 @@ func (r *ModelRegistry) convertModelToMap(model *ModelInfo, handlerType string)
 		if model.Type != "" {
 			result["type"] = model.Type
 		}
+		if model.Created != 0 {
+			result["created"] = model.Created
+		}
 		return result
 	}
 }
@@ -821,3 +825,47 @@ func (r *ModelRegistry) CleanupExpiredQuotas() {
 		}
 	}
 }
+
+
+// GetFirstAvailableModel returns the first available model for the given handler type.
+// It prioritizes models by their creation timestamp (newest first) and checks if they have
+// available clients that are not suspended or over quota.
+//
+// Parameters:
+//   - handlerType: The API handler type (e.g., "openai", "claude", "gemini")
+//
+// Returns:
+//   - string: The model ID of the first available model, or empty string if none available
+//   - error: An error if no models are available
+func (r *ModelRegistry) GetFirstAvailableModel(handlerType string) (string, error) {
+	r.mutex.RLock()
+	defer r.mutex.RUnlock()
+
+	// Get all available models for this handler type
+	models := r.GetAvailableModels(handlerType)
+	if len(models) == 0 {
+		return "", fmt.Errorf("no models available for handler type: %s", handlerType)
+	}
+
+	// Sort models by creation timestamp (newest first)
+	sort.Slice(models, func(i, j int) bool {
+		// Extract created timestamps from map
+		createdI, okI := models[i]["created"].(int64)
+		createdJ, okJ := models[j]["created"].(int64)
+		if !okI || !okJ {
+			return false
+		}
+		return createdI > createdJ
+	})
+
+	// Find the first model with available clients
+	for _, model := range models {
+		if modelID, ok := model["id"].(string); ok {
+			if count := r.GetModelCount(modelID); count > 0 {
+				return modelID, nil
+			}
+		}
+	}
+
+	return "", fmt.Errorf("no available clients for any model in handler type: %s", handlerType)
+}
diff --git a/internal/util/provider.go b/internal/util/provider.go
index 8c36ae8c..15351354 100644
--- a/internal/util/provider.go
+++ b/internal/util/provider.go
@@ -9,6 +9,7 @@ import (
 
 	"github.com/router-for-me/CLIProxyAPI/v6/internal/config"
 	"github.com/router-for-me/CLIProxyAPI/v6/internal/registry"
+	log "github.com/sirupsen/logrus"
 )
 
 // GetProviderName determines all AI service providers capable of serving a registered model.
@@ -59,6 +60,30 @@ func GetProviderName(modelName string) []string {
 	return providers
 }
 
+// ResolveAutoModel resolves the "auto" model name to an actual available model.
+// It uses an empty handler type to get any available model from the registry.
+//
+// Parameters:
+//   - modelName: The model name to check (should be "auto")
+//
+// Returns:
+//   - string: The resolved model name, or the original if not "auto" or resolution fails
+func ResolveAutoModel(modelName string) string {
+	if modelName != "auto" {
+		return modelName
+	}
+
+	// Use empty string as handler type to get any available model
+	firstModel, err := registry.GetGlobalRegistry().GetFirstAvailableModel("")
+	if err != nil {
+		log.Warnf("Failed to resolve 'auto' model: %v, falling back to original model name", err)
+		return modelName
+	}
+
+	log.Infof("Resolved 'auto' model to: %s", firstModel)
+	return firstModel
+}
+
 // IsOpenAICompatibilityAlias checks if the given model name is an alias
 // configured for OpenAI compatibility routing.
 //
diff --git a/sdk/api/handlers/handlers.go b/sdk/api/handlers/handlers.go
index 0a1df939..07edad11 100644
--- a/sdk/api/handlers/handlers.go
+++ b/sdk/api/handlers/handlers.go
@@ -295,11 +295,14 @@ func (h *BaseAPIHandler) ExecuteStreamWithAuthManager(ctx context.Context, handl
 }
 
 func (h *BaseAPIHandler) getRequestDetails(modelName string) (providers []string, normalizedModel string, metadata map[string]any, err *interfaces.ErrorMessage) {
-	providerName, extractedModelName, isDynamic := h.parseDynamicModel(modelName)
+	// Resolve "auto" model to an actual available model first
+	resolvedModelName := util.ResolveAutoModel(modelName)
+	
+	providerName, extractedModelName, isDynamic := h.parseDynamicModel(resolvedModelName)
 
 	// First, normalize the model name to handle suffixes like "-thinking-128"
 	// This needs to happen before determining the provider for non-dynamic models.
-	normalizedModel, metadata = normalizeModelMetadata(modelName)
+	normalizedModel, metadata = normalizeModelMetadata(resolvedModelName)
 
 	if isDynamic {
 		providers = []string{providerName}