Show HN: Built a local guardrail layer for Claude Code

A developer released Mati, an Apache-2.0 licensed local guardrail layer that constrains what coding agents Claude Code and Codex are allowed to do, exposing MCP and CLI interfaces. The tool is designed to prevent agents from implementing changes that break hidden product constraints, hurt performance, expose data, or cause destructive actions. The name Mati comes from a Nahuatl verb meaning "to know" or "to think.

I built Mati to give me more control over what Claude Code and Codex are allowed to do. Many important product constraints live in an engineer's or product person's head. This isn't new for engineers. We've always had important constraints that only certain people know about, but with coding agents it gets worse because we can now delegate a lot more, sometimes without realizing how much context the agent is missing. Then we delegate changes and the agent implements a change that looks reasonable but breaks some hidden constraint, hurts performance, exposes data, or does something destructive. It’s a local, Apache-2.0 licensed tool. It works with Claude Code and Codex, and also exposes MCP and CLI interfaces. The name comes from a Nahuatl verb meaning “to know” or “to think.” It’s probably a bit over-engineered. Anyway, sharing it here in case it’s useful to someone. Comments URL: https://news.ycombinator.com/item?id=49767823 https://news.ycombinator.com/item?id=49767823 Points: 1 Comments: 0