test(M-AI-05): enforce cross-user Feynman authorization

Scenario 7 E2E fix:
- Asset correct HTTP 403 (was 201 in earlier draft)
- Add before/after zero-side-effect verification (7 tables)
- Add model-call-count = 0 verification (via UsageLog)
- Add stable error structure assertion (no stack/Prisma/DATABASE_URL)
- Add Legacy path behavior documentation (known limitation:
  Legacy does not accept knowledgeItemId, no ownership check)

Real call chain:
  FeynmanExecutionRouter.evaluateFeynman():121
  → FeynmanSnapshotBuilder.build():102-110
  → knowledgeItem.userId !== input.userId → ForbiddenException
  → before AiJobCreationService.createJob():124
  → NestJS → HTTP 403

Co-Authored-By: Claude <noreply@anthropic.com>

test/m-ai-05-feynman.e2e-spec.ts

@@ -331,35 +331,134 @@ describe('M-AI-05 Feynman E2E (real infra)', () => {
   // 场景 7: 其他用户知识点请求被拒绝（权限）
   // ═══════════════════════════════════════════════════════════
 
-  describe('场景 7: 跨用户权限拒绝', () => {
+  // ═══════════════════════════════════════════════════════════
-    it('用户 2 尝试使用用户 1 的知识点 → 403 Forbidden', async () => {
+  // 场景 7: P0 跨用户权限拒绝
-      // 调用链：
-      //   Router.evaluateFeynman(userId='u-B')
-      //   → snapshotBuilder.build({ userId: 'u-B', knowledgeItemId: 'u-A的KI' })
-      //   → knowledgeItem.userId ('u-A') !== input.userId ('u-B')
-      //   → throw ForbiddenException → NestJS 全局异常过滤器 → HTTP 403
   //
-      // SnapshotBuilder 在 createJob 之前调用，ForbiddenException 在 DB 写入前传播
+  // Fixture:
+  //   User A (userId)     → JWT userToken
+  //   User B (userId2)    → JWT userToken2
+  //   KnowledgeItem A     → testKnowledgeItemId, userId=userId (User A)
+  //
+  // 请求:
+  //   User B (userToken2) + KnowledgeItem A (testKnowledgeItemId)
+  //
+  // 预期:
+  //   HTTP 403 Forbidden
+  //   SnapshotBuilder 检测 knowledgeItem.userId !== input.userId
+  //   异常在 AiJobCreationService.createJob() 之前传播
+  //   零数据库副作用  /  零模型调用
+  // ═══════════════════════════════════════════════════════════
 
-      await request(app.getHttpServer())
+  describe('场景 7: 跨用户权限拒绝', () => {
+    it('User B 提交 User A 的知识点 → 403 + 零副作用', async () => {
+      // ── 请求前计数 ──
+      const countsBefore = {
+        aiJob: await prisma.aiJob.count({ where: { userId: userId2 } }),
+        aiJobSnapshot: await prisma.aiJobSnapshot.count(),
+        outboxEvent: await (prisma as any).outboxEvent.count(),
+        aiUsageLog: await (prisma as any).aiUsageLog.count({ where: { userId: userId2 } }),
+        aiAnalysisResult: await prisma.aiAnalysisResult.count({ where: { userId: userId2 } }),
+        focusItem: await prisma.focusItem.count({ where: { userId: userId2 } }),
+        aiJobArtifact: await prisma.aiJobArtifact.count(),
+      };
+
+      // ── 跨用户请求 ──
+      // User B (userToken2) 使用 User A 的 KnowledgeItem ID
+      const res = await request(app.getHttpServer())
         .post('/api/ai-analysis/feynman')
         .set('Authorization', `Bearer ${userToken2}`)
         .send({
           knowledgeItemTitle: '光合作用',
           knowledgeItemContent: '植物利用光能的过程',
-          userExplanation: '测试解释',
+          userExplanation: 'User B 尝试评估 User A 的知识点',
-          knowledgeItemId: testKnowledgeItemId, // 属于 user1
+          knowledgeItemId: testKnowledgeItemId, // 属于 User A
+          sessionId: 'e2e-cross-user-session',
+          answerId: 'e2e-cross-user-answer',
         })
         .expect(403);
 
-      // 验证没有为 user2 创建使用 user1 知识点的 Job
+      // ── 错误响应结构 ──
-      const jobs = await prisma.aiJob.findMany({
+      // NestJS ForbiddenException → { statusCode: 403, message: 'Forbidden' }
-        where: {
+      expect(res.body).toBeDefined();
-          userId: userId2,
+      expect(res.body.statusCode || res.body.status).toBe(403);
-          targetId: testKnowledgeItemId,
+      // 不含内部堆栈
-        },
+      if (res.body.message) {
+        expect(typeof res.body.message).toBe('string');
+        expect(res.body.message).not.toContain('at ');
+        expect(res.body.message).not.toContain('node_modules');
+        expect(res.body.message).not.toContain('Prisma');
+        expect(res.body.message).not.toContain('DATABASE_URL');
+      }
+
+      // ── 请求后计数 ──
+      const countsAfter = {
+        aiJob: await prisma.aiJob.count({ where: { userId: userId2 } }),
+        aiJobSnapshot: await prisma.aiJobSnapshot.count(),
+        outboxEvent: await (prisma as any).outboxEvent.count(),
+        aiUsageLog: await (prisma as any).aiUsageLog.count({ where: { userId: userId2 } }),
+        aiAnalysisResult: await prisma.aiAnalysisResult.count({ where: { userId: userId2 } }),
+        focusItem: await prisma.focusItem.count({ where: { userId: userId2 } }),
+        aiJobArtifact: await prisma.aiJobArtifact.count(),
+      };
+
+      // ── 零副作用验证 ──
+      expect(countsAfter.aiJob).toBe(countsBefore.aiJob);                   // 0 new AiJob
+      expect(countsAfter.aiJobSnapshot).toBe(countsBefore.aiJobSnapshot);   // 0 new Snapshot
+      expect(countsAfter.outboxEvent).toBe(countsBefore.outboxEvent);       // 0 new Outbox
+      expect(countsAfter.aiUsageLog).toBe(countsBefore.aiUsageLog);         // 0 new UsageLog (≡ 0 model calls)
+      expect(countsAfter.aiAnalysisResult).toBe(countsBefore.aiAnalysisResult); // 0 new Result
+      expect(countsAfter.focusItem).toBe(countsBefore.focusItem);           // 0 new FocusItem
+      expect(countsAfter.aiJobArtifact).toBe(countsBefore.aiJobArtifact);   // 0 new Artifact
+
+      // ── 验证 User B 下绝对没有使用 User A 知识点的 Job ──
+      const crossJobs = await prisma.aiJob.findMany({
+        where: { userId: userId2, targetId: testKnowledgeItemId },
+      });
+      expect(crossJobs).toHaveLength(0);
+    });
+
+    it('Legacy 路径：User B 提交时 Router 回退到 Legacy（无 knowledgeItemId）', async () => {
+      // Legacy 路径不接受 knowledgeItemId，不执行所有权校验。
+      // 这是已知的 Legacy 设计限制 — 记录现状，不在本批修复。
+      // 生产默认保持 Legacy 时，依赖客户端不会伪造 knowledgeItemTitle/content。
+
+      // 临时关闭 Unified FeatureFlag
+      await prisma.featureFlag.update({
+        where: { name: 'FEYNMAN_ENGINE_MODE' },
+        data: { enabled: false },
+      });
+
+      const countsBefore = await prisma.aiJob.count({ where: { userId: userId2 } });
+
+      // Legacy 请求（不含 knowledgeItemId — Legacy 不支持此字段）
+      const res = await request(app.getHttpServer())
+        .post('/api/ai-analysis/feynman')
+        .set('Authorization', `Bearer ${userToken2}`)
+        .send({
+          knowledgeItemTitle: '光合作用',
+          knowledgeItemContent: '植物利用光能的过程',
+          userExplanation: 'Legacy 跨用户测试',
+        })
+        .expect(201);
+
+      // Legacy 接受请求（无所有权校验）
+      expect(res.body.jobId).toBeTruthy();
+      expect(res.body.engineMode).toBeUndefined(); // Legacy 不含此字段
+
+      const countsAfter = await prisma.aiJob.count({ where: { userId: userId2 } });
+      // Legacy 创建了 Job — 已知限制，不在本批修复
+      expect(countsAfter).toBeGreaterThan(countsBefore);
+
+      // 清理 Legacy 创建的 Job
+      if (res.body.jobId) {
+        try { await prisma.aiJob.delete({ where: { id: res.body.jobId } }); } catch {}
+      }
+
+      // 恢复 FeatureFlag
+      await prisma.featureFlag.update({
+        where: { name: 'FEYNMAN_ENGINE_MODE' },
+        data: { enabled: true, whitelist: userId },
       });
-      expect(jobs).toHaveLength(0);
     });
   });