~x-ai/grok-latest → B (2:5)

B fixes a core multi-user correctness bug: shared WEB_BROWSER_AGENT/INVITE_BROWSER_AGENT sentinels caused AgentBound on the first browser vote and blocked later humans; making PendingSession.agent optional and posting votes with no delegate restores real multi-user voting, backed by an integration test of two principals. A is a solid product feature (pool query, child pair picking, nav threading, UI button) but builds on voting rather than unblocking it.