every command
Nothing here is made up. Every block below is a real recording from a running copy of kosa8, with a plain explanation of what it means underneath.
the sealed room
A machine is a whole separate computer running on your laptop. It has its own operating system. You choose what it can see and where it can connect.
Start a new machine. You can set how much memory it gets, which folder it can see, and whether it's allowed on the internet at all.
$ kosa8 sandbox create web --memory 2048
sandbox web ready in 729msList your machines. The last column shows which machine a copy came from.
$ kosa8 sandbox ls
SANDBOX STATE CPUS MEMORY PARENT
web running 2 2048MiB -Run a program inside one of your machines.
$ kosa8 sandbox run web alpine:latest sh -c echo "isolated: $(hostname)"
isolated: kosa8-guestthe main idea
This is the part other tools don't do. Saving keeps the whole running machine, not just its files. Everything that was open is still open when you bring it back.
Save a machine exactly as it is right now, including whatever it's part-way through doing.
$ kosa8 snapshot create web --id before-change
snapshot before-change created in 1196ms (118MiB)Bring a saved machine back. Programs carry on from the moment you saved.
$ kosa8 snapshot restore before-change --name restored
restored restored in 1059msMake several copies of a running machine at once. Each copy is independent.
$ kosa8 fork web -n 3 --prefix trial
forked web into 3 sandboxes in 14640ms
trial1 192.168.127.2
trial2 192.168.127.2
trial3 192.168.127.2Try several different things at the same time, each in its own copy. kosa8 tells you which worked.
$ kosa8 explore web --variant echo "esm loader" && exit 1 --variant echo "vm-modules" && true --variant echo "babel" && sleep 1 && true
forked 3 branches in 6379ms
BRANCH RESULT TIME VARIANT
web-explore-624461 failed 356ms echo "esm loader" && exit 1
*web-explore-624462 ok 371ms echo "vm-modules" && true
web-explore-624463 ok 1360ms echo "babel" && sleep 1 && true
winner: web-explore-624462
other branches removed; --keep-all keeps them for inspectionwhat it's for
kosa8 ships with ready-made setups for eight coding assistants. It can also let an assistant control kosa8 by itself.
See the ready-made setups. Each one lists exactly which websites that assistant may use.
$ kosa8 agent kits
KIT IMAGE NETWORK DESCRIPTION
azmx node:22-alpine api.azmx.ai,api.anthropic.com,ap.. AZMX AI agent CLI in an isolated sandbox
claude node:22-alpine api.anthropic.com,registry.npmjs.. Claude Code in an isolated sandbox
codex node:22-alpine api.openai.com,registry.npmjs.org OpenAI Codex CLI in an isolated sandbox
copilot node:22-alpine api.githubcopilot.com,api.github.. GitHub Copilot CLI in an isolated sandbox
cursor node:22-alpine api2.cursor.sh,api.cursor.sh,reg.. Cursor CLI (cursor-agent) in an isolated sandbox
gemini node:22-alpine generativelanguage.googleapis.co.. Gemini CLI in an isolated sandbox
opencode node:22-alpine api.anthropic.com,api.openai.com.. OpenCode in an isolated sandbox
shell alpine:latest none A plain shell with the workspace mounted and no network
kits in ~/.kosa8/kits override built-ins of the same nameThe things an AI assistant can ask kosa8 to do on its own.
$ kosa8 mcp tools
container_exec Run a command inside a running container and return its output.
container_list List containers with their image, state and id.
container_logs Fetch a container's accumulated output.
container_run Run a container to completion and return its output. Auto-pulls the image if absent.
container_stats Report CPU, memory and pid usage for a running container.
container_stop Stop a running container (SIGTERM, then SIGKILL).
image_build Build an image from a Dockerfile in a host directory.
image_list List images available in the engine.
image_pull Pull an image from a registry into the engine.
kosa8_status Check whether the kosa8 daemon is running and report its version.
network_create Create an isolated bridge network with its own subnet.
network_list List container networks.
sandbox_create Boot an isolated microVM sandbox with its own kernel and container engine. Use this to run untrusted or experimental work away from the host.
sandbox_delete Stop and delete a sandbox and its VM.
sandbox_explore Best-of-N exploration. Forks a sandbox once per candidate command, runs each in its own branch concurrently, and reports which succeeded with timings and output. Keeps the fastest successful branch and removes the rest unless keep_all is set. Use this when several approaches are plausible and you want the answer rather than running them one at a time: branches resume with process state intact, so setup already done in the parent is shared by every branch.
sandbox_fork Fork a running sandbox into N independent copies. Every fork resumes from the parent's exact state, with processes intact, then diverges. Use this to explore several approaches in parallel from one starting point.
sandbox_list List sandboxes, including which parent each fork came from.
sandbox_pull Pull an image into a sandbox's private engine.
sandbox_run Run a container inside a sandbox's private engine, isolated from the host.
sandbox_snapshot Capture a sandbox's full state, including running processes and memory, as a snapshot.
snapshot_list List saved sandbox snapshots.
snapshot_restore Boot a sandbox from a snapshot, resuming its processes in place.
snapshot_rm Delete a snapshot (its state file, disk clone, and manifest).
volume_create Create a named volume for persistent container data.
volume_list List named volumes.familiar ground
If you already use Docker, most of what you know works here unchanged. 42 of the 48 commands behave the same way.
Run a program in a container. It downloads what it needs the first time.
$ kosa8 run alpine echo hello from a microVM
hello from a microVMSee what's currently running.
$ kosa8 ps
CONTAINER ID IMAGE STATUS NAMESproof, not promises
Everything kosa8 does is written down in a way that can't be quietly edited afterwards.
Check the record hasn't been tampered with.
$ kosa8 audit verify
audit chain intact: 908 entries verifiedSee how much you've used. This is what a bill would be based on.
$ kosa8 usage --days 30
usage since 2026-06-28 (908 audit entries)
forks 22
peak concurrent forks 3
snapshots 14
restores 23
sandbox runs 86
audit chain verified — these figures are reproducibleSee your plan and how many copies you can run at once.
$ kosa8 license status
plan: Trial (14-day trial)
concurrent forks: 4
trial: 14 days left — subscribe at https://kosa8.com/#pricingCheck your computer can run kosa8 before anything goes wrong.
$ kosa8 doctor
✓ platform darwin/arm64
✓ macOS >= 14 (save/restore) macOS 26.0.1
✓ hypervisor support kern.hv_support=1
✓ Xcode command line tools /Library/Developer/CommandLineTools
✓ kosa8d daemon reachable