Sandboxes and Worktrees: My secure Agentic AI Setup in 2026

I’ve been using AI tools since early 2021 when I was invited to test out the Copilot internal alpha at GitHub (where I spent 10 years). I’ve maintained Homebrew since 2009. I’ve now personally hit the “AI writes 90% of my code” (Dario Amodei’s early 2025 prediction for late 2025). I’ve been asked by a few folks to detail my current setup so: here it is. TL;DR: Agents bring a step change from code completion to code generation and are good enough now to one-shot many problems Sandboxing improves security and productivity by letting agents run wild without babysitting permission prompts Git worktrees parallelise work so more tokens/spend directly translates to more velocity 🤖 Agents If you’re still using AI in “code completion mode” or only GitHub Copilot, you’re missing out. Mid-to-late 2025 was when agentic tools like Claude Code and OpenAI Codex got good enough that prompting became quicker than editing, even when you’re anal about it. My experience of Claude Code and OpenAI Codex…