Side A adds a genuinely useful diagnostic script (sample-fixture) and cleanly refactors the monolithic forum.rs into cohesive submodules (access, ingest, nav, new_thread, room_members), improving maintainability with minimal behavioral risk. Side B merely deletes an entire feature (the tree view UI, its routes, and its well-covered test suite) with no replacement or migration path, which removes functionality and prior test coverage rather than adding lasting value.
A modularizes the live forum HTML stack into focused modules (nav, ingest, access, new_thread, room_members), which is lasting structure on core product code, plus adds a reusable sample-fixture helper. B only deletes the abandoned tree UI (~819 lines) and its exports—valuable cleanup, but pure subtraction without improving design of what remains.
Side A performs a substantial architectural refactor by splitting the forum code into focused modules (such as access, ingest, navigation, room members, and new-thread handling), while preserving behavior and introducing reusable helpers like ThreadNav and permission checks. It also adds a useful developer profiling script (`sample-fixture`) for diagnosing fixture processes, whereas Side B primarily removes the entire tree feature (`tree.rs`) and its exports, which is mostly feature deletion rather than an enduring improvement to the codebase.