breaking-change-detector

# Breaking Change Detector ## What this skill does This skill directs the agent to compare two versions of a codebase, API schema, or interface definition and systematically identify every change that could break existing callers. It classifies each change by severity, explains why it is breaking, and provides a concrete migration hint so consumers know exactly what they need to update. Use this before publishing a new package version, before deploying an API change that existing clients depend on, or during a code review to catch unintended contract changes. ## How to use ### Claude Code / Cline Copy this file to `.agents/skills/breaking-change-detector/SKILL.md` in your project root. Then ask: - *"Use the Breaking Change Detector skill to compare the old and new versions of our API."* - *"I changed `src/auth/index.ts`. Use the Breaking Change Detector skill to find any breaking changes."* Provide: the old version (paste, file path, or git ref) and the new version. ### Cursor Add the instructions below to your `.cursorrules` or paste them into the Cursor AI pane. Then share both the old and new code side by side. ### Codex Paste both versions clearly labeled as "OLD VERSION" and "NEW VERSION" and ask Codex to follow the instructions below. ## The Prompt / Instructions for the Agent When asked to detect breaking changes, follow this process: ### Step 1 — Establish what constitutes the public contract Before comparing, identify what is "public" — i.e., what ext...