From fork() to Fleet: Designing an Agent Sandbox Cloud — Abhishek Bhardwaj, OpenAI
Jul 13, 2026 · 44:34
Abhishek Bhardwaj from OpenAI explains the design of a secure, scalable agent sandbox cloud, arguing that microVMs (like Firecracker and Cloud Hypervisor) provide the strongest isolation for running untrusted AI-generated code despite performance trade-offs, and that persistent disk storage is the next frontier for unlocking long-running, stateful agent tasks. He compares runtime isolation technologies from simple fork-exec to containers (with namespaces and cgroups) to gVisor, and advocates for hardware-backed virtualization via microVMs to prevent guest exploits from reaching the host kernel. For persistence, he details incremental block-level snapshotting using copy-on-write filesystems and always-on distributed filesystems, enabling reliable checkpointing and Monte Carlo-style exploration. Orchestration challenges include low-latency sandbox creation through pre-warming or memory snapshots, and intelligent routing based on cached snapshot layers to minimize restore time. The talk positions storage and fast snapshot restore as key enablers for advanced agent capabilities, such as long-horizon tasks and failure recovery.
