watchFile never fires when vfs uses a real dir

Version

main

Platform

macOS 26.2

Subsystem

vfs

What steps will reproduce the bug?

test.js:

const vfs = require('node:vfs');
const fs = require('fs');

const v = vfs.create(new vfs.RealFSProvider('/tmp'));

let called = false;
v.watchFile('/a.txt', { interval: 50 }, () => {
  called = true;
});

fs.writeFileSync('/tmp/a.txt', 'x');

setTimeout(() => {
  console.log('called?', called);
}, 300);

$ node --experimental-vfs test.js

How often does it reproduce? Is there a required condition?

Always

What is the expected behavior? Why is that the expected behavior?

called? true

file changed, the listener should run

What do you see instead?

called? false

Additional information

No response

从 test.js 以及 RealFSProvider 和 watchFile 的 node:vfs 入口开始，然后使用 node --experimental-vfs test.js 重现该问题。追踪 /tmp/a.txt 发生变化后 listener 未被调用的原因；完成标准是示例报告 called? true。