The static UntrustedData options are gone. An assembly declares its formatter
resolvers with [assembly: CultCacheFormatterResolver(typeof(R))];
CultDocumentMessagePackSerialization.OptionsFor(assembly) composes them ahead
of CultDocumentResolver and StandardResolver, once per assembly, and hands
assemblies that declare nothing the base Options. Generated codecs and the
reflective SerializeUntyped/DeserializeUntyped path both read
OptionsFor(typeof(X).Assembly). No registration call, no mutable options, no
load order.
CultMessagePackSecurity copies UntrustedData and supplies a collision-resistant
comparer over CultRecordRef<T>.Key.Value, so ref-keyed dictionaries
deserialize.
Tests: RefKeyedDictionaryRoundTrips failed on 825b4f7 ("No hash-resistant
equality comparer available"); DeclaredResolverEncodesValueTypeAsPositionalArray
and UnknownAssemblyGetsBaseOptions did not compile there (new API);
InteropNoteBytesUnchanged is a pin whose payload constant was captured on
825b4f7. BenchItem, the one unkeyed [CultDocument] in any consumer (in-memory
benchmark, no store), gains [Key]s in its existing slot order.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>