更新：models/routes/services/templates/docs

app/routes/problems.py

@@ -18,23 +18,15 @@ def get_student_problems(student_id):
 @main_bp.route("/api/students/<int:student_id>/problems", methods=["POST"])
 @login_required_json
 def add_student_problem(student_id):
-    """为学员添加问题（同步模式：先删再加）"""
+    """为学员添加问题（增量模式：只添加或更新，不删除已有）"""
     student = Student.query.get_or_404(student_id)
     data = request.get_json()
 
     problems = data.get("problems", [])
-    submitted_ids = set()
 
-    # 删除旧的问题（如果勾选被取消）
-    existing = StudentProblem.query.filter_by(student_id=student_id).all()
-    for e in existing:
-        if e.problem_id not in [p.get("problem_id") for p in problems]:
-            db.session.delete(e)
-
-    # 添加或更新问题
+    # 添加或更新问题（不删除已有的）
     for p in problems:
         problem_id = p.get("problem_id")  # 这是 problems.id
-        submitted_ids.add(problem_id)
 
         # 检查是否已存在
         existing = StudentProblem.query.filter_by(