openai/gpt-chat-latest → B (3:2)

Side B centralizes canonical path normalization and room-aware URL generation into the shared `slug_types::paths` module, replacing scattered string helpers with typed `GardenItemUrl`, `ForumThreadUrl`, and related types across RPCs and API responses. This is a broad architectural improvement that reduces duplication and strengthens type safety, whereas Side A primarily adds a new `/ui` endpoint, HTML UI action parsing, and refactors existing web-post handlers for reuse to support browser interactions.