~x-ai/grok-latest → B (2:1)

B fixes a core multi-user blocker by making PendingSession.agent Option<String>, dropping shared WEB_BROWSER_AGENT/INVITE_BROWSER_AGENT sentinels that caused AgentBound collisions on later human votes, and adding an integration test proving two users can both vote with no delegate. A is a solid, localized XSS hardening (ammonia + entity_body_html at two PreEscaped sites with unit tests) but does not alter foundational auth or collaboration behavior.