# SinkSeal: git-hook guardrails for AI coding agents

> Source: <https://dev.to/kurotomo/sinkseal-git-hook-guardrails-for-ai-coding-agents-2d9i>
> Published: 2026-09-02 05:23:23+00:00

I built this after watching an AI-agent-built demo feature get wired straight to a live SMS/voice vendor — no guard, no synthetic-tenant check, just the same code path production used. A routine demo session produced real phone charges.

SinkSeal is a set of git hooks (bash, no runtime dependency beyond git + grep/sed) that catch three things on every commit and push, regardless of which agent (Claude Code, Cursor, Codex, or a human) writes the code:

CI catches a bad diff *after* it's already pushed. A git hook catches it before the commit even lands, regardless of which coding agent (or human) wrote the code — the enforcement lives in the hook, not in any one tool's configuration or system prompt.

```
git clone https://github.com/kuro-tomo/sinkseal
./sinkseal/install.sh /path/to/your/repo
```

This copies the hooks self-contained into `<repo>/.githooks/`

, so it survives even if you later delete the sinkseal checkout, and it's inherited automatically by any git worktree of that repo.

Free and MIT-licensed: [https://github.com/kuro-tomo/sinkseal](https://github.com/kuro-tomo/sinkseal)

Feedback especially welcome on the pattern-matching approach — it's inherently a probabilistic safety net (regex-based), not a completeness guarantee, and I'd rather know where it's weak than oversell it.