feat: support choice+open dual question generation with judgment anchors

- Add judgment and followupHints fields to QuestionBankItem entity
- Rewrite generateQuestions prompt for 3:7 choice:open ratio
- Extract parseGeneratedQuestion function with type-aware parsing
- Add 29 unit tests: 14 prompt content + 15 parse logic
- Total: 97 tests passing (59 baseline + 38 new)

server/src/assessment/entities/question-bank-item.entity.spec.ts

@@ -0,0 +1,85 @@
+import { QuestionBankItem, QuestionType, QuestionDifficulty, QuestionDimension, QuestionBankItemStatus } from './question-bank-item.entity';
+
+describe('QuestionBankItem entity', () => {
+  describe('existing fields', () => {
+    it('should create an instance with default questionType', () => {
+      const item = new QuestionBankItem();
+      expect(item.questionType).toBeUndefined();
+    });
+
+    it('should set and get basic fields', () => {
+      const item = new QuestionBankItem();
+      item.questionText = '【场景】你在编写代码... 【问题】请描述你会如何处理';
+      item.questionType = QuestionType.SHORT_ANSWER;
+      item.options = null;
+      item.correctAnswer = null;
+      item.keyPoints = ['规范文档化', '源头统一'];
+      item.difficulty = QuestionDifficulty.STANDARD;
+      item.dimension = QuestionDimension.PROMPT;
+      item.basis = '知识库原文依据';
+      item.status = QuestionBankItemStatus.PENDING_REVIEW;
+
+      expect(item.questionText).toBe('【场景】你在编写代码... 【问题】请描述你会如何处理');
+      expect(item.questionType).toBe(QuestionType.SHORT_ANSWER);
+      expect(item.options).toBeNull();
+      expect(item.correctAnswer).toBeNull();
+      expect(item.keyPoints).toEqual(['规范文档化', '源头统一']);
+      expect(item.difficulty).toBe(QuestionDifficulty.STANDARD);
+      expect(item.dimension).toBe(QuestionDimension.PROMPT);
+      expect(item.basis).toBe('知识库原文依据');
+      expect(item.status).toBe(QuestionBankItemStatus.PENDING_REVIEW);
+    });
+  });
+
+  describe('judgment field', () => {
+    it('should accept judgment text for choice question', () => {
+      const item = new QuestionBankItem();
+      item.judgment = 'B正确，因为提供了具体约束和角色设定。A错误在于过于笼统。C错误在于过度细节但缺乏核心约束。D错误在于错误建议。';
+      expect(item.judgment).toBe('B正确，因为提供了具体约束和角色设定。A错误在于过于笼统。C错误在于过度细节但缺乏核心约束。D错误在于错误建议。');
+    });
+
+    it('should accept judgment text for open question', () => {
+      const item = new QuestionBankItem();
+      item.judgment = '关键考点：会话管理——长对话导致上下文窗口膨胀 通过标准：说出"让AI总结之前内容+开新窗口"即通过';
+      expect(item.judgment).toContain('通过标准');
+      expect(item.judgment).toContain('会话管理');
+    });
+
+    it('should allow null judgment', () => {
+      const item = new QuestionBankItem();
+      item.judgment = null;
+      expect(item.judgment).toBeNull();
+    });
+  });
+
+  describe('followupHints field', () => {
+    it('should accept array of followup hints', () => {
+      const item = new QuestionBankItem();
+      item.followupHints = [
+        '如果只回答"开新窗口"没说怎么带上前情：追问"开新窗口后之前讨论的结论不就丢了吗？怎么把有用信息带过去？"',
+        '如果内容不完整：追问"还有没有更好的办法？"',
+      ];
+      expect(item.followupHints).toHaveLength(2);
+      expect(item.followupHints[0]).toContain('开新窗口');
+      expect(item.followupHints[1]).toContain('更好的办法');
+    });
+
+    it('should accept single followup hint', () => {
+      const item = new QuestionBankItem();
+      item.followupHints = ['追问如何保留之前结论'];
+      expect(item.followupHints).toHaveLength(1);
+    });
+
+    it('should accept empty array', () => {
+      const item = new QuestionBankItem();
+      item.followupHints = [];
+      expect(item.followupHints).toHaveLength(0);
+    });
+
+    it('should allow null followupHints', () => {
+      const item = new QuestionBankItem();
+      item.followupHints = null;
+      expect(item.followupHints).toBeNull();
+    });
+  });
+});

server/src/assessment/entities/question-bank-item.entity.ts

@@ -86,6 +86,12 @@ export class QuestionBankItem {
   @Column({ type: 'text', nullable: true })
   basis: string | null;
 
+  @Column({ type: 'text', nullable: true })
+  judgment: string | null;
+
+  @Column({ type: 'simple-json', nullable: true, name: 'followup_hints' })
+  followupHints: string[] | null;
+
   @Column({ name: 'created_by', nullable: true, type: 'text' })
   createdBy: string | null;