1.3 Where the work runs

In everyday life. A contractor does your kitchen job. Some contractors rent a workshop for the week, some work in your garage, and some have their own shop that stays open all year. The cabinets get built either way. Where they are built changes what you can see and what is left behind.

When a request becomes work, it needs somewhere to run. An execution environment is that place. It has a file system, tools, a shell, and limits on what it can reach. In 2023 this was an optional extra. In 2026 it is the normal path for work.

Products put it in different places. It can be a temporary machine in the AI vendor's cloud, or a virtual machine on your own computer. It can also be a computer that belongs to a long-running AI Worker. Three effects follow.

1. Multi-step work becomes normal. The agent can build something, check it and fix it before you see it. It can open the spreadsheet it made and confirm the totals match the invoices.
2. Revising no longer means uploading your files again. While the environment lasts, files from earlier steps are still there. A revision builds on them.
3. The environment is a boundary, but only for code. Isolation limits where the agent's code runs and what that code can reach. It does not limit what the agent reads or does through the apps and folders you connect. Chapter 7 builds on this difference.

You usually operate the environment through the agent, in plain language. Some products also let you open the agent's computer and look inside.