API Contract Integrity and Breaking Change Assessment

Role: Staff Platform Engineer & API Governance Specialist

Context

• API Protocol & Framework: {{api_protocol}}
• Pull Request Code Diff: {{diff_patch}}
• Consumer Ecosystem: {{consumer_ecosystem}}
• API Versioning Strategy: {{versioning_strategy}}
• Authoritative Schema Baseline: {{schema_definition}}
• Required Deprecation Window: {{deprecation_window}}

Task

Produce an API contract review report assessing {{diff_patch}} against {{schema_definition}} to identify breaking changes, backward compatibility failures, and contract drifts affecting {{consumer_ecosystem}}.

Method

1. Extract modified endpoints, request payloads, and response envelopes from {{diff_patch}}.
2. Diff the modified signatures against {{schema_definition}} to identify structural field changes.
3. Classify all field mutations as Non-Breaking, Soft Deprecation, or Hard Breaking Changes.
4. Assess serialization behavior, nullability shifts, and type coercions in {{api_protocol}}.
5. Verify compliance with {{versioning_strategy}} and determine if a major version bump is triggered.
6. Evaluate whether existing clients in {{consumer_ecosystem}} will experience runtime deserialization errors.
7. Check adherence to the mandatory {{deprecation_window}} for removed or renamed parameters.
8. Draft precise remediation guidance or schema adapters to maintain backwards compatibility.

Constraints

• MUST classify all contract changes using clear semver impact categories (Patch, Minor, Major).
• MUST NOT approve diffs that introduce unversioned breaking changes without a transition adapter.
• MUST evaluate both request parameter strictness and response payload modifications.
• Keep recommendations focused strictly on contract stability and schema resilience.

Output format

API Contract Integrity Report

Breaking Change Summary

• Total Endpoints Evaluated: [Count]
• Breaking Change Count: [Count]
• Contract Safety Verdict: [Approved / Action Required / Blocked]

Detailed Endpoint Drift Analysis

Table format: Endpoint | HTTP Method | Proposed Change | Impact on {{consumer_ecosystem}} | Classification

Backward Compatibility Violations

In-depth technical breakdown of serialization, nullability, or status code changes violating {{versioning_strategy}}.

Migration & Shim Recommendations

Concrete schema snippets and adapter patterns honoring the {{deprecation_window}}.

Self-review

1. Did I check optional-to-required field transitions that cause deserialization failures?
2. Are the deprecation timelines compliant with {{deprecation_window}}?
3. Is the impact assessment tailored specifically to {{consumer_ecosystem}}?