fix: option display + partial credit grading

- Option display: use slice(1) instead of regex to strip letter prefix
- Grader prompts: add explicit partial credit guidance (5-7 for partial, 0-2 only for off-target)

server/src/assessment/graph/nodes/grader.node.ts

@@ -107,6 +107,8 @@ export const graderNode = async (
 2. 完整性：他们是否遗漏了任何重要内容？
 3. 深度：解释是否充分？
 
+**重要：评分请给部分分数。不完全正确不等于0分——回答方向对、意思接近但不够完整时请给5-7分。完全不沾边才给0-2分。**
+
 请提供：
 1. 0 到 10 的评分。
 2. 建设性的反馈。
@@ -134,6 +136,8 @@ export const graderNode = async (
 2. 網羅性：重要な内容が欠落していませんか？
 3. 深さ：説明は十分ですか？
 
+**重要：点数は部分点をつけてください。完全に正解でなくても0点ではありません——方向性が合っていて、部分的に正しい場合は5〜7点を与えてください。全く見当違いの場合のみ0〜2点としてください。**
+
 以下を提供してください：
 1. 0 から 10 までのスコア。
 2. 建設的なフィードバック。
@@ -161,6 +165,8 @@ Evaluate:
 2. Completeness: Did they miss anything important?
 3. Depth: Is the explanation sufficient?
 
+**Important: Give partial credit. Incomplete answers are not 0 — if the direction is right and partially correct, give 5-7. Only give 0-2 for completely off-target answers.**
+
 Provide:
 1. A score from 0 to 10.
 2. Constructive feedback.

web/components/views/AssessmentView.tsx

@@ -610,7 +610,7 @@ export const AssessmentView: React.FC<AssessmentViewProps> = ({
                                     {currentQuestion.options.map((opt: string, i: number) => {
                                         const letter = optionLabels[i];
                                         const isSelected = selectedChoice === letter;
-                                        const displayText = opt.replace(/^[A-D][.)、]\s*/, '');
+                                        const displayText = opt.slice(1);
                                         return (
                                             <button
                                                 key={letter}
@@ -857,7 +857,7 @@ export const AssessmentView: React.FC<AssessmentViewProps> = ({
                                                                  {q.options?.map((opt: string, oi: number) => {
                                                                      const letter = String.fromCharCode(65 + oi);
                                                                      const isAnswer = letter === q.correctAnswer;
-                                                                     const displayText = opt.replace(/^[A-D][.)、]\s*/, '');
+                                                                     const displayText = opt.slice(1);
                                                                      return (
                                                                          <span key={oi} className={cn(
                                                                              "px-3 py-1 rounded-lg font-medium",

web/components/views/QuestionBankDetailView.tsx

@@ -405,7 +405,7 @@ export default function QuestionBankDetailView() {
                           {item.options.map((opt, i) => {
                             const letter = String.fromCharCode(65 + i);
                             const isCorrect = item.correctAnswer === letter;
-                            const displayText = opt.replace(/^[A-D][.)、]\s*/, '');
+                            const displayText = opt.slice(1);
                             return (
                               <div key={i} className={`flex items-center gap-2 px-3 py-2 rounded-xl text-sm ${isCorrect ? 'bg-emerald-50 border border-emerald-200' : 'bg-slate-50'}`}>
                                 <span className={`inline-flex items-center justify-center w-6 h-6 rounded-lg text-[10px] font-black shrink-0 ${isCorrect ? 'bg-emerald-500 text-white' : 'bg-slate-200 text-slate-500'}`}>{letter}</span>