Abstract

An agent platform is usually costed as though an agent were a process, which sets the per-agent floor at a container runtime's minimum reservation — 128–512 MB on commodity platforms. At that floor a fleet of a million agents is a datacenter, and every design decision downstream of the estimate is made in its shadow. We take the estimate apart. An idle agent is three separable things: the state it will resume from, the execution context that holds its loop, and the isolation boundary its code runs behind. These have no reason to cost the same, and measured on one laptop they differ by five orders of magnitude. State at rest is a row: 477 bytes on disk, so a million dormant agents occupy 454.6 MiB, written at 309,789 agents/s and resumed in 0.034 ms in-process. Execution at rest is a goroutine: 601 bytes of heap, identical on every run, so a million live loops are 573.0 MB and each starts in 125 ns. Isolation is the expensive one, and it is expensive for a reason: an in-process V8 context costs 0.13 ms but runs only JavaScript, while a microVM costs 309 ms — 2377× more — and is the only one of the two that can run a test suite, a package manager or a shell. The conclusion is not that containers are wasteful. It is that a fleet pays for isolation per running agent, not per registered one, while the industry estimate charges the isolation price to every agent whether or not it is doing anything. We give the capacity model this implies, and we are explicit about what 601 bytes is: a floor for an agent holding nothing, not a forecast for an agent holding a conversation.