DSL typing: name-less 3-arg path(pattern, component, childrenFn) collapses the route map to never #642

Symptom

Adding a single name-less route using the 3-arg children-function form:

path("/section/stream", StreamPage, () => [
  loader(StreamLoader),
  loading(<div>Loading...</div>),
])

collapses the entire app's generated route map: Rango.Path resolves to never, producing cascading never type errors across every href/Link.to/named-route usage in the app — not just at the offending route.

Expected

Unnamed routes are deliberately excluded from the route map — ExtractRoutesFromItem maps TName extends UnnamedRoute to {} (src/urls/type-extraction.ts:85) — so a name-less route in any call form should contribute {} and leave sibling routes' types intact. The 2-arg form (path(pattern, component)) and the named 3-arg form both behave correctly.

Actual

With the name-less children-fn overload, the item's inferred type apparently falls through the TypedRouteItem conditional chain in ExtractRoutesFromItem (src/urls/type-extraction.ts:79), and the UnionToIntersection in ExtractRoutesFromItems (:127-135) absorbs the result into never for the whole tuple, wiping the map.

Workaround

Name the route: path("name", "/section/stream", StreamPage, () => [...]) — restores correct inference. (Matches repo conventions anyway, which is why this stayed latent.)

Pointers

• Extraction: src/urls/type-extraction.ts (ExtractRoutesFromItem :79, ExtractRoutesFromItems :127)
• Overload types: src/urls/path-helper-types.ts (the children-fn overload's inference is the suspect)
• Runtime (fine, unaffected): src/urls/path-helper.ts

Discovery context

Hit while adding e2e routes for PPR shell caching (#641) in both tests/cloudflare-basic and e2e/test-app — reproduced identically in two independent apps, so it is the overload, not app-specific augmentation. Likely fix territory: the name-less children-fn overload's TypedRouteItem type parameters (or a defensive never-absorbing guard in ExtractRoutesFromItems so one bad item can never nuke the map — arguably worth doing regardless as a blast-radius fix).