openai/gpt-chat-latest → B (3:2)

Side B removes the legacy GitDiscovery projection path and makes the evidence model authoritative by requiring emission metadata, deleting fallback lookup code, and simplifying epoch/commit pages to rely only on Evidence events. This is a substantive architectural cleanup that eliminates dual data paths and updates tests accordingly, whereas Side A is largely a large-scale refactor consolidating web posting into the `/ui` RPC flow with mostly equivalent behavior moved between modules.