tests/concurrency/ticket-status-race.test.ts fires 20 genuinely concurrent TicketsRepository.updateStatus calls from the same starting version against real Postgres. Passes on the first run, confirming (rather than assuming) 003-ticketing's existing atomic version-checked updateMany already holds under real concurrency — no implementation change needed (research.md §4). Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>