openai/gpt-5.3-chat → A (8:1)

Side A introduces substantial new functionality: deterministic and typed block masking, a full prose tokenizer for item references, improved URL parsing (including punctuation trimming and newline handling), stricter DSL validation rules, and integration into HTML linkification. It also adds extensive tests and refactors multiple components to support these features. Side B is comparatively minor, mainly removing a wrapper element in a template and adding CSS refinements. The scope, complexity, and impact of A are significantly greater.