openai/gpt-chat-latest → B (3:1)

Side B implements a substantial identity model change: OAuth providers become private links to a canonical UUID account, adds Reddit OAuth alongside GitHub, updates login/account flows, introduces provider-link conflict handling, persists linked providers, and fixes trust-weight application during batched projection updates. Side A mainly adds persistent theme selection across pages and login plus correct room-aware URL generation in RPC responses, which are useful UX and API improvements but are narrower in architectural impact than the new authentication and identity design.