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Structured Output & Schema EnforcementHigh ReliabilityHigh-Risk Workflow

API Contract Diff Checker

Compares old/new API specifications and produces deterministic breaking-change reports suitable for CI and release gates.

Version

0.1.0

Last Updated

Apr 22, 2026

Verification Type

schema validation, manual review required

Downloads

0

Required inputs

  • old_contract (json)

    Previous stable API specification.

  • new_contract (json)

    Proposed updated API specification.

Expected outputs

  • contract_diff_report (markdown)

    Human-readable summary of contract changes.

  • breaking_changes (json)

    Machine-readable breaking change list.

Included checks and assets

  • scripts/compare_openapi.py (script)

    Compares OpenAPI path/method surfaces and flags deterministic breaking changes.

  • references/breaking-change-rules.md (reference)

    Ruleset for classifying contract diffs as breaking or non-breaking.

  • references/versioning-guidance.md (reference)

    Version bump guidance for breaking API revisions.

Failure modes

  • Spec drift from runtime behavior can hide real breakage.
  • Complex schema changes may require manual semantic review.
  • Policy exceptions can reduce reliability if overused.

Ideal use cases

  • OpenAPI pull request checks
  • Release compatibility gates
  • SDK stability reviews

Example runs

User endpoint contract update

Validated sample run

Detects deleted method and required request field addition.

Input preview

old_openapi.json + new_openapi.json

Output preview

2 breaking changes and version bump recommendation

Changelog summary

  • 0.1.0 · Apr 22, 2026

    Initial release for deterministic API compatibility diffing.

Links

Inspect the source, read authored documentation, or download the published skill bundle.

DownloadSourceDocs