Code Change Guardian

A Codex skill that shows what may break before a code change, guides behavior-preserving refactors, and records the proof in a native Markdown report that opens directly in Codex.

What it does

• Maps direct, transitive, contractual, operational, and test impact
• Finds callers, consumers, side effects, implicit contracts, and blind spots
• Scores credible failure modes with an explainable risk model
• Creates an ordered, reversible change plan
• Requires approval before changing project files
• Uses characterization tests and baseline evidence for safe refactors
• Verifies an existing diff without rewriting it
• Maintains one CODE-CHANGE-REPORT.md from analysis through final proof

Three modes

• impact — analyze a proposed change without editing code
• refactor — analyze, approve, protect behavior, change incrementally, and verify
• verify — inspect an existing diff, branch, commit, or pull request for regressions

Install

npx --yes codex-code-change-guardian@latest

Example prompts

Use $code-change-guardian to analyze what could break if we replace JWT authentication with sessions. Do not edit code.

Use $code-change-guardian to safely extract Voice Mode from this large React component. Create the report first and ask before changing files.

Use $code-change-guardian to verify my current diff and identify unprotected regressions.

Output

The skill creates CODE-CHANGE-REPORT.md in the repository root. The report contains:

• executive verdict and scope;
• blast-radius map;
• failure modes and risk scores;
• contracts to preserve;
• safe change sequence;
• exact verification commands and results;
• unknowns, blind spots, and rollback strategy.

All generated report content is in English.

License

MIT