openai/gpt-5.2-chat → A (3:2)

Side A introduces a comprehensive URL canonicalization system with a new url_rules module, restructures ItemId semantics around full canonical URLs, updates parsing, parent/breadcrumb logic, Reddit/YouTube normalization, and propagates these changes across the server, tests, and projection logic. This is a deep architectural shift affecting identity, storage, and routing. Side B adds meaningful features (external garden index fix, resolver refactor, GitHub import cards with rendering and tests), but it is more feature-scoped. Overall, Side A has broader and more foundational impact on the codebase.