Copperhead edits KiCad source directly instead of regenerating it

Copperhead runs an agent over KiCad projects by editing the s-expression source files directly rather than regenerating them from scratch. Regenerate the whole file and the diff becomes unreadable, so a reviewer can't tell what changed in a schematic or board file. Editing the source in place keeps that diff reviewable, which matters for anyone who has to sign off on a board before it goes to fab.

The tool outputs gerbers, firmware and documentation, and keeps schematics, docs and budgets in sync as it works. For verification, it doesn't ask an LLM to judge whether the board is correct. It hands that job to KiCad's own electrical rule check and design rule check.

Traction is small and reported without inflation: 195 GitHub stars, 513 monthly npm installs, 234 points on Show HN. The CLI is Apache-2.0 licensed. Cloud pricing is $49 per user per month, free for open hardware projects.

A lot of agent tooling reaches for an LLM to check its own work. Copperhead reaches for the domain's existing deterministic checker instead, so a passing run means something a human already trusts before the agent ever touched the file. That's the part worth copying for anyone building an agent over a structured source format. Ask whether the tool edits in place and verifies with the format's own checker, or regenerates and hopes an LLM catches what it broke.