# Breaking Changes

> Detect breaking changes in Codex updates by comparing current API surface against changelog. Maps impacts to specific plugin files.

- Skill: `fusengine/breaking-changes-3` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add fusengine/breaking-changes-3`
- Raw SKILL.md: https://api.skillmd.com/api/skills/fusengine/breaking-changes-3/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Integrations & APIs
- Author: fusengine (https://skillmd.com/u/fusengine)
- Updated: 2026-09-22
- Page: https://skillmd.com/skills/fusengine/breaking-changes-3

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# Breaking Changes Detection Skill

## Overview

Compares Codex API changes against our plugin ecosystem to detect compatibility issues.

## API Surface File

The `api-surface.md` reference contains our current known API:
- Hook types and their matchers
- Agent frontmatter fields
- Plugin manifest schema
- Skill SKILL.md format
- Script CLI flags used

## Detection Workflow

1. **Load** current api-surface.md
2. **Fetch** latest Codex API docs
3. **Diff** for added/changed/removed APIs
4. **Grep** our plugins for each changed API
5. **Report** with file:line impact mapping

## Impact Assessment

| Change Type | Severity | Example |
|-------------|----------|---------|
| Removed API | BREAKING | Hook type deleted |
| Changed schema | BREAKING | Frontmatter field renamed |
| New required field | BREAKING | Mandatory new param |
| Deprecated API | DEPRECATED | Old hook still works |
| New optional API | NEW | New hook type added |

## References

- [API Surface](references/api-surface.md)
- [Migration Guide Template](references/templates/migration-guide.md)