Give route-shaped dev server strings distinct types
Turbopack's entrypoints keep routes in maps keyed by string namespaces that
look alike but rarely equal each other: the routes map is keyed by route
pathname ("/blog"), and the app entrypoints map by entry name
("/blog/page"). Mixing them up compiles fine and silently never matches —
which is how the dev server came to announce every app route as added on
every update (fixed at the bottom of this stack).
Brand the two namespaces (TurbopackRouteKey, AppEntryName) the way EntryKey
already guards entry keys: a plain string can't be used where a branded key
is expected, and the brands can't be used in each other's place. Reverting
the announcement fix no longer compiles:
error TS2345: Argument of type 'TurbopackRouteKey' is not assignable to
parameter of type 'AppEntryName'.
error TS2345: Argument of type 'string' is not assignable to parameter
of type 'TurbopackRouteKey'.
Strings enter the namespaces at the NAPI boundary (route construction in
swc/index.ts) and leave through message payloads, where the brands widen
back to plain strings. normalizedPageToTurbopackStructureRoute returns an
entry name — per its own comment it maps a normalized page path back to
Turbopack's entry key — and is typed accordingly.
No runtime change.
