- Coordinator subscribes to account.state_changed over Redis pub/sub: going
live marks the account claimable at once; disabled/deleted/error tears the
owning runner down immediately (≤30s) instead of waiting for the lease TTL.
- delete_account now publishes account.state_changed:deleted after dropping the
account from sync:live, so teardown is event-driven, not just fencing.
- AccountRunner gains a verify loop (defense in depth): it periodically confirms
the account is still live and flags itself dead if not; the coordinator reaps
dead runners and releases their lease. Zombie loops are structurally impossible.
- New core event user.active (SPEC §8.3), published on login and on every WS
connect; consumed for tier promotion in step 5.
- Acceptance: added event-driven teardown test (isolated from fencing/verify).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>