fix: shuffle choice options per session + clean followup hints

- Options shuffled with correctAnswer remapped at session creation
- Followup hints strip conditional prefix (如果只说了XX，追问：)

server/src/assessment/assessment.service.ts

@@ -505,18 +505,35 @@ private async getModel(tenantId: string): Promise<ChatOpenAI> {
               targetCount,
             );
 
-            questionsFromBank = selectedItems.map(item => ({
-              id: item.id,
-              questionText: item.questionText,
-              questionType: item.questionType,
-              options: item.options,
-              correctAnswer: item.correctAnswer,
-              judgment: item.judgment,
-              keyPoints: item.keyPoints,
-              difficulty: item.difficulty,
-              dimension: item.dimension,
-              basis: item.basis,
-            }));
+            questionsFromBank = selectedItems.map(item => {
+              let options = item.options;
+              let correctAnswer = item.correctAnswer;
+              if (item.questionType === 'MULTIPLE_CHOICE' && options && options.length > 0 && correctAnswer) {
+                const labels = ['A', 'B', 'C', 'D'];
+                const optTexts = options.map((o: string) => o.replace(/^[A-D][.)、]\s*/, ''));
+                const correctIdx = correctAnswer.charCodeAt(0) - 65;
+                const correctText = correctIdx >= 0 && correctIdx < optTexts.length ? optTexts[correctIdx] : null;
+                const indices = optTexts.map((_: any, i: number) => i);
+                for (let i = indices.length - 1; i > 0; i--) {
+                  const j = Math.floor(Math.random() * (i + 1));
+                  [indices[i], indices[j]] = [indices[j], indices[i]];
+                }
+                options = indices.map((origIdx: number, newPos: number) => `${labels[newPos]}${optTexts[origIdx]}`);
+                correctAnswer = correctText ? labels[indices.indexOf(correctIdx)] : correctAnswer;
+              }
+              return {
+                id: item.id,
+                questionText: item.questionText,
+                questionType: item.questionType,
+                options,
+                correctAnswer,
+                judgment: item.judgment,
+                keyPoints: item.keyPoints,
+                difficulty: item.difficulty,
+                dimension: item.dimension,
+                basis: item.basis,
+              };
+            });
 
             const answerKey: Record<string, { correctAnswer?: string | null; judgment?: string | null; followupHints?: string[] | null }> = {};
             selectedItems.forEach(item => {

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

@@ -254,7 +254,8 @@ Format your response as JSON:
 
     let followupHintMsg: AIMessage | null = null;
     if (shouldFollowUp && followupHints.length > 0) {
-      const hint = followupHints[Math.min(currentFollowUpCount, followupHints.length - 1)];
+      let hint = followupHints[Math.min(currentFollowUpCount, followupHints.length - 1)];
+      hint = hint.replace(/^如果[^，,]*[，,]\s*追问[：:]\s*/i, '').replace(/^如果[^。]*[。]\s*/i, '');
       const hintLabel = isZh
         ? `让我帮你完善一下：${hint}`
         : isJa