`run()` scope

```ts
run(() => {
const pid = seInterval(() => {
console.log("print every 1s")
}, 1 * s)
return () => clearInterval(pid)
}, when?: string)
```
Those that are wrapped in `run()` scope will run every time (not just once) current `` is in view and stop (call returned function) when out of view.

Locate the implementation or entry points for run() and , then read how view visibility is currently handled. Done means callbacks wrapped in run() execute each time the current render-scope enters view and the returned cleanup function is called when it leaves, with the optional when condition accounted for.

Written by the indexing model from the issue text.