openai/gpt-chat-latest → A (4:1)

Side A fixes a user-facing design flaw by removing shared sentinel browser delegates, changing pending sessions and browser posts to use no delegate, updating API types to `Option<String>`, and adding an integration test proving multiple human users can vote without conflicting `AgentBound` state. Side B is a good reducer bugfix that moves the zero-ratio guard before `ensure_item` and `voted_pairs` mutations to prevent ghost state, but it is narrower in scope and impact than the cross-cutting authentication and voting correctness fix in Side A.