Why is service worker at src/service-worker.js? instead of TLD?

[eettaa]

https://github.com/expo/fyi/blob/main/enabling-web-service-workers.md and associated example https://github.com/expo/examples/tree/cfb044b07385773fac2247be968cc5c0b13be8bf/with-workbox both put the service-worker.js file in src/.... does this interfere with the service worker's scope and control as defined here? https://developer.chrome.com/docs/workbox/service-worker-lifecycle/#control-and-scope? I think the end goal is for the service worker to have dominion over the entire app.

More generally, what is this 'src/' directory? In any case, my app/ directory (which is the app root containing e.g. webpack-config) doesn't already contain a src/ directory yet (just top level code including App.tsx)... I'm wondering if the 'src/' directory is a magic directory from the perspective of webpack or something?

Thanks!