~anthropic/claude-sonnet-latest → A (8:2)

Side A fixes an actual deadlock bug (holding a RwLock read guard across nested lock acquisitions) with a real code change, adds a regression test, and improves test infrastructure (timeouts, log-file redirection to avoid pipe deadlocks). Side B is purely a planning/design document (PLAN.md) with no code changes, providing aspirational value but no immediate functional or bugfix contribution.