On November 3, 2026, Google Cloud announced plans to donate Agent Substrate and gVisor to the Cloud Native Computing Foundation (CNCF) in Sandbox status, alongside OpenRL. The CNCF’s Agent Substrate project page lists Agent Substrate at Sandbox maturity. Google’s announcement describes the runtime as a way to preserve AI agents’ session state while freeing up compute between tasks.
How Agent Substrate separates session state from compute
Google describes Agent Substrate as a Kubernetes-based control and data plane. Each Actor holds an agent session’s filesystem, environment variables, memory state and network rules. A shared pool of pre-warmed Kubernetes Pods, called Workers, supplies compute when an Actor needs to run.
In Google’s account, the system parks requests for suspended Actors. When a request arrives, a controller assigns a warm Worker, restores the Actor’s memory and disk state from tiered storage, then routes the request to it. Once the Actor is idle, its state is snapshotted and the Worker slot is freed.
That design targets a common mismatch in interactive agent workloads: Google says a typical session may spend 90–95% of its time waiting for model inference, external APIs or human review. In the waiting scenario it describes, the agent retains its state while using zero CPU. Keeping a dedicated Pod running avoids a cold start but leaves compute allocated during that idle time; scaling a container to zero frees compute, but may require rebuilding its environment when it wakes.
Isolation options and Google’s performance claims
Google describes gVisor as a user-space application kernel that intercepts system calls to isolate untrusted code from the host kernel. For workloads that need hardware virtualization or custom kernel modules, Google says Agent Substrate also supports Cloud Hypervisor microVMs through the same API.
Google claims Agent Substrate can restore an Actor’s memory and disk state in under 500 milliseconds. It contrasts that with conventional cold-storage wake-ups that, in its account, can exceed 20 seconds when a container must clone repositories, reinstall packages and rebuild memory. The announcement presents these as Google’s performance claims, not as an independently reported benchmark. Google also says the system can activate, suspend and resume thousands of agents per second without creating a new Kubernetes Pod object for each operation.
Google described Agent Substrate as open source and ready for testing, and called version 1.0 its latest release at the time of the announcement. It also listed Agent Substrate sessions and demonstrations for KubeCon + CloudNativeCon North America in Salt Lake City, scheduled for November 9–12, 2026.
