Agent Substrate enters the CNCF Sandbox: idle agent sessions are checkpointed out, with the project claiming 10x container density
NVIDIA has donated Agent Substrate, an open-source runtime for running large numbers of sandboxed AI agents on Kubernetes, to the CNCF Sandbox. Agents spend most of their time waiting on a prompt, a tool result or a model response; keeping one Pod per session holds memory for idle sessions, while creating Pods on demand pays a multi-second cold start at every step and loses state. Agent Substrate multiplexes many sessions over a small pool of warm worker Pods, checkpointing idle sessions including memory and filesystem and restoring them onto whichever worker is free, and the project reports 10x higher density than standard containers.