Expand description
OP#12 - Schema-vs-schema derivation admission.
Given a chained GTS schema ID like gts.A~B~C~, this module validates that
each derived schema may be admitted under its base:
- B (derived from A) must be admissible under A
- C (derived from A~B) must be admissible under A~B
Admission requires Valid(derived) ⊆ Valid(base) - every valid instance of
the derived schema is also a valid instance of the base. That is the same
accepted-instance-set inclusion that schema evolution checks, so this module
owns no keyword semantics of its own: it calls the checker in
crate::schema_evolution and adds the two admission rules that inclusion alone
does not express.