Pathless layout with standard layout

Hi there! I'm new to TSR and a bit puzzled by the routing syntax compared to simpler ones like in Astro. Basically, I want to achieve this:

/auth/register
/auth/login

/auth/register
/auth/login

Both routes should share a layout but accessing

/auth

/auth

should throw a 404. Currently, I have

/auth
/auth/_auth.tsx
/auth/_auth/register.tsx
/auth/_auth/login.tsx

/auth
/auth/_auth.tsx
/auth/_auth/register.tsx
/auth/_auth/login.tsx

But accessing

/auth

/auth

does not throw a 404.

Thanks a lot!