Sandboxes for AI Agents

A guide to designing sandboxes that let AI coding agents test and validate their own changes, covering seven sandbox designs (Island, Local Dev, Devbox, Ephemeral, Preview Environment, Hybrid, Shadow) and their trade-offs between realistic, safe, and fast/cheap. It also covers multi-repo sandbox patterns, seeding test data, dev-only login, and having agents leave "receipts" on PRs as proof of validation.