1. Do not open a public issue for a security problem.
2. Report privately via GitHub Security Advisories.
3. Include a description, steps to reproduce, impact, and a suggested fix if you have one.

You will get an acknowledgement within 48 hours and a timeline for a fix.

TestGuard is a local CLI with a deliberately small surface:

• One runtime dependency, exact-pinned: ajv, which validates every document the tool reads or writes against the spec. Install scripts are disabled (.npmrc). vitest is development-only.
• No network access. Nothing is uploaded, fetched, or reported anywhere.
• No credentials. There is nothing to authenticate to.
• Writes are confined to .testguard/ in the probed project and to scratch git worktrees under the system temp directory, which are removed after each run. With --in-place, the mutated files are restored — on success, on failure, and on SIGINT/SIGTERM.
• Publishing uses OIDC Trusted Publishing to npm and PyPI, so the release pipeline holds no registry tokens and npm provenance attestations are generated automatically. Homebrew publishing uses a dedicated SSH deploy key scoped only to raccioly/homebrew-tap; it cannot access this repository or any other repository.

testguard.claims.json contains replace strings that are written into your source and then executed by your test runner, inside a worktree of your repository. Treat the file exactly as you treat source:

• Review changes to it in pull requests.
• In CI, a pull request that edits the claims file has the same power as a pull request that edits a test — no more, no less. Do not run probe on untrusted pull requests with secrets in the environment, for the same reason you would not run their tests that way.
• The schema rejects absolute paths and .. traversal in fault targets, so a fault cannot address files outside the probed project.

• Keep Node.js ≥ 20 and current.
• Prefer the default worktree mode; use --in-place only when you need uncommitted changes probed.
• Read .testguard/evidence.json before sharing it: it contains file paths, test names, and content hashes of your project.