GuardedBy

Which field of the model records its owner, written as a selector so the compiler checks it.

inline, because the field's name is what db renders into the owner condition of four statements, and the only place that name exists as something a compiler can check is the selector's own tree. Read at compile time it is the model's field; typed by hand it is a string that is right until somebody renames the field.

The body calls owningField and reaches nothing private, which is what an inline method expanded in a user's companion object is allowed to do.

owning's body, after the selector has given up its name.

Public only because an inline method's expansion has to be able to call it from wherever the declaration is written. A caller who writes the name by hand gets what they asked for, which is the thing owning exists to make unnecessary.

What one handwritten route becomes in the table: the guard's own pages, and that route wrapped.

A handwritten route has no Action, so there is nothing to test actions against and the wrapper reaches it directly. A page is guarded or it is public, which is the same rule Guarded[Index.type] = Guarded.public states in the other direction, and public wraps nothing and carries nothing, so an unguarded application's table is exactly what it was.

The login page comes out of every declaration rather than being mounted once somewhere else, because the two have to arrive together: a route that redirects to a page nobody mounted is a 404 at the end of every refusal. The table takes distinct afterwards, which is safe only because one guard builds its routes once and hands the same instances to every declaration it makes.