GROUP_CONTEXT

Injection token for providing group ancestry to mappers and components.

Re-provided in two places: 1. GroupFieldComponent provides a context whose groupPath() is the parent path extended by its own key (e.g. 'address' or 'user.address'). 2. createArrayItemInjector provides a sentinel with an empty groupPath, resetting the chain at array boundaries — descendants of an array item that re-enter a group compose paths INSIDE the array item, matching the property-derivation collector's keying.

mapFieldToInputs reads this to scope DOM IDs and override-store keys so the same leaf key can appear in different groups without colliding (#401).

Inject with { optional: true } because top-level fields with no group ancestor (and no enclosing array) won't have the token provided. The token IS present for fields inside an array even when no inner group exists — the array-boundary sentinel makes injection succeed with an empty groupPath.