openai/gpt-chat-latest → B (5:1)

Side B performs a substantial architectural migration: it replaces many individual REST endpoints with a unified RPC batch API, introduces room-scoped commands and data structures (room/thread separation), updates the reducer and event model, and adapts the CLI, server, tests, and shared types to the new design. Side A adds useful infrastructure such as a Dockerfile, deployment config, an event log helper, and a persisted view counter, but these are comparatively isolated additions rather than a project-wide API and data model evolution.