fix: restore main runtime sources and cache consistency

exam_pkg/grader.py

@@ -219,6 +219,41 @@ def grade_fill_blank(answer: Dict) -> Dict:
     student_answers = answer.get('student_answer', [])
     max_score = answer.get('max_score', 4.0)
 
+    if not isinstance(student_answers, list):
+        logger.warning(
+            "填空题学生答案格式错误: 期望列表，实际为 %s",
+            type(student_answers).__name__,
+        )
+        return {
+            "question_id": answer.get('question_id'),
+            "score": 0,
+            "max_score": max_score,
+            "grading_status": "failed",
+            "details": {
+                "error": f"学生答案格式错误，期望列表，实际为 {type(student_answers).__name__}"
+            },
+        }
+
+    for index, student_answer in enumerate(student_answers):
+        if not isinstance(student_answer, str):
+            logger.warning(
+                "填空题学生答案第 %s 项格式错误: 期望字符串，实际为 %s",
+                index + 1,
+                type(student_answer).__name__,
+            )
+            return {
+                "question_id": answer.get('question_id'),
+                "score": 0,
+                "max_score": max_score,
+                "grading_status": "failed",
+                "details": {
+                    "error": (
+                        f"填空题学生答案第 {index + 1} 项格式错误，期望字符串，"
+                        f"实际为 {type(student_answer).__name__}"
+                    )
+                },
+            }
+
     # 归一化答案格式（修复 LLM 生成的扁平数组问题）
     blank_count = question_content.get('data', {}).get('blank_count', 0)
     correct_answers = _normalize_fill_blank_answer(correct_answers, blank_count)