test: 目录对齐赛道二成果物规范（tests/ 迁移+实验报告+提效测量脚本）

- src/test 迁移至根目录 tests/（16 测试 + fixtures/manual），导入改为 ../src/
- 新增 tsconfig.test.json 独立编译测试；.vscode-test.mjs / package.json / .gitignore 同步
- 新增 tests/test-execution-log.md、tests/test-cases.md（116 用例清单）
- 新增 tests/measure/measure-review-time.mjs + performance-comparison.md（提效测量）
- 重命名 3 个中文报告文件为 demo-*-coverage-report.md
- git rm --cached 解除 vsix 跟踪；README 标注演示视频进行中

tests/ai-empty-response.test.ts

@@ -0,0 +1,100 @@
+import * as assert from 'assert';
+import { parseJsonResponse, chatWithRetry } from '../src/ai/engine';
+import { EmptyContentError } from '../src/ai/providers/base';
+import type { AIProvider } from '../src/ai/providers/base';
+import type { ChatOptions } from '../src/ai/providers/base';
+import { OpenAICompatibleProvider } from '../src/ai/providers/openai-compatible';
+
+const OPTIONS: ChatOptions = {
+  model: 'test',
+  temperature: 0,
+  maxTokens: 1024,
+  timeoutMs: 5000,
+};
+
+suite('AI Empty Response Handling', () => {
+  test('parseJsonResponse throws empty-response error on blank input', () => {
+    assert.throws(() => parseJsonResponse(''), /空响应|empty response/);
+    assert.throws(() => parseJsonResponse('   \n\t '), /空响应|empty response/);
+  });
+
+  test('parseJsonResponse parses valid JSON normally', () => {
+    const parsed = parseJsonResponse('{"findings":[]}') as { findings: unknown[] };
+    assert.deepStrictEqual(parsed.findings, []);
+  });
+
+  test('chatWithRetry retries once on EmptyContentError', async () => {
+    const calls: string[] = [];
+    const provider = {
+      chat: async (system: string): Promise<string> => {
+        calls.push(system);
+        if (calls.length === 1) {
+          throw new EmptyContentError('finish_reason=length');
+        }
+        return '{"findings":[]}';
+      },
+    } as unknown as AIProvider;
+
+    const result = await chatWithRetry(provider, 'sys', 'user', OPTIONS);
+    assert.strictEqual(result, '{"findings":[]}');
+    assert.strictEqual(calls.length, 2);
+  });
+
+  test('chatWithRetry propagates error when retry also returns empty', async () => {
+    const provider = {
+      chat: async (): Promise<string> => {
+        throw new EmptyContentError('finish_reason=length');
+      },
+    } as unknown as AIProvider;
+
+    await assert.rejects(
+      () => chatWithRetry(provider, 'sys', 'user', OPTIONS),
+      EmptyContentError
+    );
+  });
+
+  test('chatWithRetry does not retry on non-empty-content errors', async () => {
+    let calls = 0;
+    const provider = {
+      chat: async (): Promise<string> => {
+        calls++;
+        throw new Error('boom');
+      },
+    } as unknown as AIProvider;
+
+    await assert.rejects(() => chatWithRetry(provider, 'sys', 'user', OPTIONS), /boom/);
+    assert.strictEqual(calls, 1);
+  });
+
+  test('openai-compatible reports max_tokens truncation clearly', async () => {
+    const originalFetch = globalThis.fetch;
+    globalThis.fetch = (async () => ({
+      ok: true,
+      json: async () => ({
+        choices: [{ message: { content: null }, finish_reason: 'length' }],
+      }),
+      text: async () => '',
+    })) as unknown as typeof fetch;
+
+    try {
+      const provider = new OpenAICompatibleProvider('key', 'http://localhost', 'test', 'Test');
+      await assert.rejects(
+        () =>
+          provider.chat('sys', 'user', {
+            model: 'm',
+            temperature: 0,
+            maxTokens: 8192,
+            timeoutMs: 5000,
+          }),
+        (err: unknown) => {
+          assert.ok(err instanceof EmptyContentError);
+          assert.match((err as Error).message, /max_tokens/);
+          assert.match((err as Error).message, /8192/);
+          return true;
+        }
+      );
+    } finally {
+      globalThis.fetch = originalFetch;
+    }
+  });
+});