M0-M11 狩夜人笔记初始实现：11里程碑+86测试

tests/unit/atomic-write.test.ts

@@ -0,0 +1,41 @@
+import { describe, it, expect, afterEach } from 'vitest';
+import nodePath from 'node:path';
+import os from 'node:os';
+import { promises as fs } from 'node:fs';
+import { writeFileAtomic, withFileLock } from '../../apps/desktop/src/main/safe/atomic-write';
+
+const dir = nodePath.join(os.tmpdir(), 'dsh-atomic-test');
+afterEach(async () => { await fs.rm(dir, { recursive: true, force: true }); });
+
+describe('writeFileAtomic (FR-S5)', () => {
+  it('写入内容并回读一致', async () => {
+    const p = nodePath.join(dir, 'a.md');
+    await writeFileAtomic(p, '# 标题\n内容');
+    expect(await fs.readFile(p, 'utf8')).toBe('# 标题\n内容');
+  });
+  it('不残留临时文件', async () => {
+    const p = nodePath.join(dir, 'b.md');
+    await writeFileAtomic(p, 'x');
+    const files = await fs.readdir(dir);
+    expect(files).toEqual(['b.md']);
+  });
+  it('覆盖已有文件', async () => {
+    const p = nodePath.join(dir, 'c.md');
+    await writeFileAtomic(p, 'old');
+    await writeFileAtomic(p, 'new');
+    expect(await fs.readFile(p, 'utf8')).toBe('new');
+  });
+});
+
+describe('withFileLock 并发安全', () => {
+  it('同文件请求串行执行', async () => {
+    const p = nodePath.join(dir, 'lock.md');
+    const order: number[] = [];
+    const t = (id: number, delay: number) => withFileLock(p, async () => {
+      order.push(id);
+      await new Promise(r => setTimeout(r, delay));
+    });
+    await Promise.all([t(1, 20), t(2, 1), t(3, 1)]);
+    expect(order).toEqual([1, 2, 3]);
+  });
+});