~anthropic/claude-sonnet-latest → B (6:4)

B introduces a clean, testable URL scheme change (`/~/` browse routing) with new ItemId methods, unit tests, integration tests, and removes dead theme-switching machinery, yielding a simpler and more maintainable routing model. A adds real but narrower value (sorting vote history, morph preview card, fullscreen layout) with a good test, but includes large speculative CSS duplication across three theme files and a doc rewrite, which is more surface area for less structural payoff than B's URL refactor.