While testing adonis-modal I ran into a typing issue worth raising here, and I think it shows that Macroable on its own won't cover everything.

Right now I set up the type augmentation like this:

declare module '@adonisjs/inertia' {
  interface Inertia<Pages> {
    modal(...): ModalResponse
  }
}

It works fine in a normal server tsconfig, but it breaks around the barrel. In a second TS program that type-checks a caller of inertia.modal(...) without importing the @adonisjs/inertia barrel, say a Tuyau client tsconfig that pulls controllers in through the generated registry, the merge silently no-ops. The Inertia class is only nameable through the barrel re-export, while HttpContext.inertia references the class by an internal path, so a third-party interface Inertia merge only attaches when the barrel is actually loaded in that program. The only workaround I found is force-loading the barrel with a type-only import, kept alive by a dummy marker export so tsc doesn't drop it, which is a hack.

Macroable would clean up the runtime side, but not this. The class stays reachable only through the re-export, so the merge keeps failing in programs that don't load the barrel. Compare that with Request/Response, which are declared and exported from the same public module they're augmented on, so third-party augmentation just works.

Would it make sense to also expose an augmentable Inertia interface from the public entry (or anchor the class the way @adonisjs/core/http does with Request), so declare module '@adonisjs/inertia' attaches without consumers having to force-load the barrel?