Structured Field Values ownership and compatibility

Ownership and Equality

Bare values have value equality and no mutable state. Byte sequences copy incoming arrays, and copy-out operations cannot change the stored bytes or hash. Boolean singletons are safe to reuse as bare values.

Items, inner lists, parameters, and collections are mutable and use reference equality. Item/inner-list constructors copy supplied parameter collections. Mutate parameters through their owning node; a StructuredFieldMember does not introduce a second collection. Explicitly sharing a mutable item between lists is possible, so modifying that item is visible to both lists.

Breaking Changes

• Scalar classes now derive from BareItem, not StructuredFieldItem. Wrap values in new StructuredFieldItem(bareValue) before attaching parameters; inspect parsed scalars through item.Value.
• Replace ListMember and DictionaryMember with StructuredFieldMember. Supply parameters to the item or inner-list constructor, not FromItem.
• Replace null-valued parameters with BooleanItem.True. TryGetValue returning true always yields a non-null bare value.
• Replace mutable byte-array access with .Bytes for reading or .ToArray() for a copy.
• Replace TokenMember, TokenValue, TokenParameter, TokenElements, and TokenInnerList with the corresponding ordinary method and type: ItemType.Token.
• Mapper models and nested models must be classes; propagate class, new() constraints through generic helpers. Invalid mappings fail at construction.
• Empty list/dictionary input can now succeed in TryParse. HTTP helpers distinguish a missing header from a present empty value.
• Explicit Boolean true parameters serialize in shorthand. ToString() remains diagnostic-only and must not be used as a substitute for serialization.