Api contract diff

Skill sisodiabhumca/agent-skills/skills/api-contract-diff

Production-Ready Agent Skills : product analytics, growth experiments, CRM, research synthesis, postmortems, data contracts, SaaS spend, compliance, architecture maps, and LLM eval and many more.

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npx -y skills add sisodiabhumca/agent-skills --skill api-contract-diff

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Vendor-neutral skill to compare two OpenAPI 3 specifications and produce a structured contract change report with breaking-change detection.

SKILL.md

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When to invoke

When you need to assess API changes between two versions of an OpenAPI 3.x spec.
When you need to flag likely breaking changes (removed paths, removed operations, removed/changed required request fields, response schema removals).

Inputs needed

--old: Path to the older OpenAPI 3 JSON file.
--new: Path to the newer OpenAPI 3 JSON file.
Optional --out: Path to write a JSON report.

Workflow

Load both OpenAPI documents (JSON).
Extract operations indexed by (path, method).
Compare:
- Added/removed paths and operations.
- Parameter additions/removals (path/query/header).
- Request body requiredness and JSON schema required properties.
- Response status codes present/removed.
Label changes as breaking, non_breaking, or unknown_risk.

Output format

JSON with:

summary: counts of breaking/non-breaking/unknown.
breaking_changes: list of items with kind, location, and details.
non_breaking_changes: list of items.
unknown_risk_changes: list of items.

Guardrails

Do not assume semantic meaning beyond what is expressed in OpenAPI.
Mark schema-type changes as unknown_risk unless clearly breaking (e.g., removed required property).
Prefer false positives over false negatives for breaking changes.

Reference code

api_contract_diff.py