修复自动模式优先使用后台默认生图模型

lib/ai/auto-agent-graph.ts

@@ -427,6 +427,17 @@ async function refineRouteWithAgent(
   }
 
   try {
+    const { db } = await import("@/lib/db");
+    const { siteSettings } = await import("@/lib/db/schema");
+    const [settings] = await db.select().from(siteSettings).limit(1);
+    const configuredDefaultModelId = settings?.canvasAutoModeDefaultModelId || null;
+    if (configuredDefaultModelId && baseRoute.id === configuredDefaultModelId) {
+      console.log(
+        `[Auto Agent] Keep admin default model for auto mode: ${baseRoute.displayName}`
+      );
+      return baseRoute;
+    }
+
     const {
       getEnabledAiModelsWithProvider,
       getAgentAiModelWithProvider,