Toggling `isolatedModules` in `tsconfig.json` while running the compiler in `watch` mode, doesn't re-emit `const enums`, unlike toggling `preserveConstEnums`, which does

まだ誰も着手していません。

### 🔎 Search Terms

isolatedModules enums not re-emitted on watch mode

### 🕗 Version & Regression Information

Tested on `6.0.1-rc` and `6.0.0-dev.20260309`

I didn't research if this is a regression or not. It may have always been like this but never reported.

### ⏯ Playground Link

_No response_

### 💻 Code

```ts
const enum TestEnum {
a = 1,
b = 3,
c = 5,
}

const x = TestEnum.b
```

### 🙁 Actual behavior

Toggling `isolatedModules` doesn't change the emitted code when running `tsc` in `watch` mode. However, if the compilation is redone, it does re-emit correctly.

### 🙂 Expected behavior

Should modify the emitted code for `const enums` when the option is changed on `watch` mode, since it does change when re-compiling from scratch.

### Additional information about the issue

For comparison, toggling `preserveConstEnums` in `tsconfig.json` does correctly modify the emitted code in `watch` mode.

Clarification: the issue occurs when `preserveConstEnums` is not defined at all in `tsconfig.json`, so the emit behavior for `const enum`s is implicit from it.

提供された const enum の例を tsc の watch モードで再現し、まず tsconfig.json の isolatedModules を切り替え、次に preserveConstEnums を切り替えます。出力された結果を新規コンパイルの結果と比較し、その後、watch モードの構成と emit の無効化パスを追跡します。isolatedModules の変更によって、完全な再起動を必要とせずに const enums が再度 emit されれば完了です。

索引モデルが issue の本文から書いたものです。