resolveField marked every anonymous field embedded, so walkFields (mapping, field index, validate) and fillStruct (deserializer) flattened a json-tagged embedded struct, while conversions.To/encoding/json on the write path nests it under the tag, mapping and deserializing it at the wrong path. An anonymous field is now embedded only without a json tag name, matching encoding/json; fillStruct also recurses into a value nested struct. No current type has a tagged embedded struct, so runtime behavior is unchanged; this hardens the reflection walker.
Dominik Schmidt
69c517a8b2