Go hard on agents, not on your filesystem

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jaiGo hard on agents, not on your filesystem.

Use jai for effortless containment of AI agents on Linux.

People are already reporting lost files, emptied working trees, and wiped home directories after giving AI tools ordinary machine access.

There's a gap between giving an agent your real account and stopping everything to build a container or VM. jai fills that gap. One command, no images, no Dockerfiles — just a light-weight boundary for the workflows you're already running: quick coding help, one-off local tasks, running installer scripts you didn't write.

Use AI agents without handing over your whole account. jai gives your working directory full access and keeps the rest of your home behind a copy-on-write overlay — or hidden entirely.

One-line installer scripts, AI-generated shell commands, unfamiliar CLIs — stop running them against your real home directory. Drop jai

in front and the worst case gets a lot smaller.

No images to build, no Dockerfiles to maintain, no 40-flag bwrap invocations. Just jai your-agent

. If containment isn't easier than YOLO mode, nobody will bother.

One command. No setup required.

Prefix your commandjai codex

, jai claude

, or just jai

for a shell.

CWD stays writable

Your working directory keeps full read/write access inside the jail.

Home is an overlay

Changes to your home directory are captured copy-on-write. Originals are untouched.

Rest is locked down/tmp

and /var/tmp

are private. All other files are read-only.

Pick the level of isolation that fits your workflow.

| Casual | Strict | Bare | | |---|---|---|---| | Home directory | Copy-on-write overlay | Empty private home | Empty private home | | Process runs as | Your user | Unprivileged jai user | Your user | | Confidentiality | Weak — most files readable | Strong — separate UID | Medium — your UID, but home hidden | | Integrity | Overlay protects originals | Full isolation | Full isolation | | NFS home support | Yes | No | Yes |

jai is free software, brought to you by the Stanford Secure Computer Systems research group and the Future of Digital Currency Initiative. The goal is to get people using AI more safely.

jai is not trying to replace containers. It fills a different niche.

Great for reproducible, image-based environments. Heavier to set up for ad-hoc sandboxing of host tools. No overlay-on-home workflow.

Powerful namespace sandbox. Requires explicitly assembling the filesystem view — oft

Not a security mechanism. No mount isolation, no PID namespace, no credential separation. Linux documents it as not intended for sandboxing.

jai is a casual sandbox — it reduces the blast radius, but does not eliminate all the ways AI agents can harm you or your system. Casual mode does not protect confidentiality. Even strict mode is not equivalent to a hardened container runtime or VM. When you need strong multi-tenant isolation or defense against a determined adversary, use a proper container or virtual machine. Read the full security model →