4cc8b3c01c
ToJson now throws ArgumentException when a Body key collides with a reserved envelope field (uri/viewerId/uuid/bid/try/cat/pubSeq/playSeq); FromJson reuses the same shared ReservedEnvelopeKeys HashSet. ReceiveNodeResultCode expanded from 9 to 31 codes to mirror the full enums.md catalog. Two regression tests added for the collision guard and PascalCase uri serialization. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>