diff --git a/src/components/image-editor/model3d-generation/Model3dGenerationSubmission.ts b/src/components/image-editor/model3d-generation/Model3dGenerationSubmission.ts
index 9a09340e1..4a79d1940 100644
--- a/src/components/image-editor/model3d-generation/Model3dGenerationSubmission.ts
+++ b/src/components/image-editor/model3d-generation/Model3dGenerationSubmission.ts
@@ -207,6 +207,10 @@ export function buildModel3dSubmissionPlan({
     return finishImageToModel({ source, generation, ...placement });
   }
 
+  // 契约以后新增端点时在这里显式失败：否则它会静默走成文生请求，丢掉新端点的输入。
+  if (dialog.mode !== 'model3d-text-to-model') {
+    return { ok: false, message: MODEL3D_MODE_UNSUPPORTED_REASON };
+  }
   const prompt = dialog.prompt.trim();
   if (!prompt) {
     return { ok: false, message: MODEL3D_TEXT_PROMPT_REQUIRED_MESSAGE };