Root cause for the lingering mulligan failure: the inline conditional
expression in MsgEnvelope.ToObject
JsonValueKind.Number => el.TryGetInt64(out var l) ? l : el.GetDouble(),
unified its branches to the common implicit-convertible type. long→double
is implicit, so both branches collapsed to double and the integer value
silently widened. Inside an array (idxList:[2]), each element came back
as boxed double; OfType<long> in ExtractIdxList then filtered every
entry out, so swapIndices arrived empty and BuildSwapResponse echoed
the unchanged hand — exactly the diff-against-Deal mismatch the client
flagged as "Card swap failed: AbandonCards[2]/DrawCards[]".
Extract a ParseNumber helper that returns object explicitly so each
branch boxes its own runtime type. Also harden ExtractIdxList to accept
any boxed numeric type (long/int/double/decimal/string) so a future
JSON-parser drift can't silently regress this path again.
Two regression tests:
- FromJson_NumericArray_PreservesLongTypeOnEachElement: confirms the
fix at the JSON-parse layer with a hardcoded "{\"idxList\":[2,3]}".
- Swap_WithIdxListContainingTwo_ProducesHandWithFreshIdxAtPosition1:
exercises the dispatch end-to-end with a Body holding a real boxed
long; asserts position 1 of the response hand is the fresh deck idx 4.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
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>
