Batch 9 refused any overlap between two types' ids, which forbade the migration
CompatibleSchemaIds exists for: v2 declares v1's id while v1's class stays
registered (Soul F8). The rule is now owner beats lister. A type owns its own
schema id; any number of types may list an id as compatible beside its owner,
registering in either order. A record under an id resolves to its owner, else to
the one type listing it. An id no type owns and several list names no single
type, so a record under it is refused, typed (CultSchemaConflictException naming
the id and the listers), where it resolves: refusing at registration would
depend on whether the owner had registered yet.
A second owner of one id is still refused at registration, typed. A schema id
hashes the schema's name and version, so the only second owner is a type of the
same name and version, which the name-and-version check already meets; the
separate own-id lookup could never fire and is gone.
Tests: an owner and a lister register in both orders, the owner's id resolves to
the owner, the lister's own id to the lister, and without the owner to the
lister; two listers register in both orders, a record under their id is refused
typed with no owner and resolves to the owner with one, registered before or
after them; a cache with v1 beside v2 reads each version's records as its own
type, in both registration orders. The emitted-fixture note says why a fixture
is emitted now that v1/v2 pairs no longer need hiding from the shared registry.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
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