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

B removes a real bug-prone redirect flow (env-var-based URLs, full page reloads) in favor of a consistent SPA-like fragment morph pattern, unifying auth pages with the shared layout() and reducing duplicated markup via form_inner(). A is a well-tested, focused fix to a visual gradient bug, which is valuable but narrower in scope than B's structural simplification and consistency improvement across auth flow and CSS themes.