We Gave an Agent Production Code Access and Then Tried to Sleep at Night — Moritz Johner, Form3
Jul 20, 2026 · 21:57
Moritz Johner of Form3 explains that giving a coding agent production code access turns it into a supply chain actor, and the blast radius is an architecture decision. His team built PatchPilot to automate CVE patching across thousands of repositories, splitting it into a deterministic Go layer that handles dangerous operations (GitHub write access, CI triggering) and an agent layer that only edits files. The agent remediates vulnerabilities by bumping dependencies, verifying builds, and fixing CI failures, but a prompt injection could escape via the Docker socket, which kept him up at night. To contain that, they moved the agent into a firecracker microVM with its own kernel and separate network policies per layer. Johner argues that where you draw the line between deterministic and agentic code defines your security model, and warns that existing agent sandboxes are worthless when a Docker socket is involved.
