# API Breaking Change Review

> Use when performing api breaking change review — aPI backwards compatibility review template for detecting breaking changes in REST, GraphQL, and gRPC APIs. Covers endpoint modifications, schema changes, response format changes, deprecation policy enforcement, and versioning strategy validation to prevent disruption to API consumers.

- Skill: `cloudthinker-ai/api-breaking-change-review` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cloudthinker-ai/api-breaking-change-review`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cloudthinker-ai/api-breaking-change-review/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Integrations & APIs
- Author: cloudthinker-ai (https://skillmd.com/u/cloudthinker-ai)
- Updated: 2026-09-08
- Page: https://skillmd.com/skills/cloudthinker-ai/api-breaking-change-review

---


# API Breaking Change Review Skill

Review PR **#{{ pr_number }}** in **{{ repository }}** for **{{ api_type }}** breaking changes.

## Workflow

### Phase 1 — Breaking Change Detection

```
BREAKING CHANGE ANALYSIS
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
[ ] Endpoint/field removal:
    [ ] No existing endpoints removed without deprecation
    [ ] No required fields removed from responses
    [ ] No existing enum values removed
[ ] Type changes:
    [ ] No response field type changes (string -> int)
    [ ] No narrowing of accepted input types
    [ ] No changes to nullable/required status
[ ] Behavioral changes:
    [ ] No changes to default values
    [ ] No changes to error codes for existing scenarios
    [ ] No changes to pagination behavior
    [ ] No changes to sorting/filtering defaults
[ ] Authentication/Authorization:
    [ ] No new auth requirements on existing endpoints
    [ ] No scope/permission changes for existing operations
```

### Phase 2 — Versioning Strategy

```
VERSIONING CHECK
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
[ ] Versioning approach:
    - URL path versioning: /v1/, /v2/
    - Header versioning: Accept-Version
    - Query parameter: ?version=2
[ ] Version bump required: YES / NO
[ ] Previous version still supported: YES / NO
[ ] Version sunset timeline defined: ___
[ ] Consumer migration guide provided: YES / NO
```

### Phase 3 — Deprecation Policy

```
DEPRECATION REVIEW
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
[ ] Deprecated items marked with:
    [ ] Deprecation header in responses
    [ ] Documentation annotation
    [ ] OpenAPI/schema deprecated flag
    [ ] Sunset date communicated
[ ] Deprecation timeline:
    - Deprecation announced: ___
    - Migration deadline: ___
    - Removal date: ___
[ ] Affected consumers notified: YES / NO
[ ] Usage metrics for deprecated endpoints: ___
```

### Phase 4 — Consumer Impact

```
CONSUMER IMPACT ASSESSMENT
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
[ ] Known consumers identified: ___
[ ] Consumer contract tests exist: YES / NO
[ ] Contract tests pass with changes: YES / NO
[ ] SDK updates required: YES / NO
[ ] Documentation updated: YES / NO
[ ] Changelog entry added: YES / NO
```

## Counter-Rationalizations

| Shortcut | Counter | Why |
|----------|---------|-----|
| "We can skip some steps for this case" | Adapt the workflow steps, don't skip them | Skipped steps are where incidents and oversights originate |
| "The user seems to already know what to do" | Complete all workflow phases with the user | The workflow catches blind spots that experience alone misses |
| "This is a minor case, full process is overkill" | Scale the process down, don't turn it off | Minor cases become major when unstructured; the process scales, not disappears |
| "I'll fill in the details later" | Complete each section before moving on | Deferred details are forgotten; real-time capture is more accurate |
| "The template output isn't necessary" | Always produce the structured output format | Structured output enables comparison, audit trails, and handoff to other teams |

## Output Format

Produce a breaking change report with:
1. **Breaking changes found** (list with severity)
2. **Backwards-compatible alternatives** for each breaking change
3. **Versioning recommendation** (bump version or make additive)
4. **Consumer migration plan** if breaking changes are necessary
5. **API contract test results**