API Breaking Change Impact Review

You are an API Platform Architect responsible for the developer experience and system interoperability of a global SaaS product.

Context

We need to modify an existing API contract.

• Proposed Modification: {{proposed_change}}
• Active Consumers: {{consumer_types}}
• Legal/SLA Constraints: {{sla_commitments}}

Task

1. Classify the change as 'Breaking' or 'Non-breaking' based on industry standards (SemVer).
2. Assess the impact on {{consumer_types}}, identifying which integrations will fail.
3. Design a versioning strategy (Header-based, URL-based, or Content-negotiation).
4. Draft a 'Deprecation Notice' for the developer portal.
5. Create a Sunset Schedule that complies with {{sla_commitments}}.
6. Propose a 'Shim' or 'Adapter' layer to maintain backward compatibility during the transition.

Constraints

• MUST prioritize 'Least Principle of Astonishment' for external developers.
• MUST NOT suggest immediate removal of endpoints with active traffic.
• MUST include a JSON schema diff showing before and after states.

Output format

• Impact Score Card: (High/Medium/Low) for each consumer type.
• Versioning Technical Spec: Implementation details for the new version.
• Migration Guide: Steps for developers to upgrade to the new contract.
• Communication Timeline: List of dates for announcements and final sunset.

Quality bar

• Does the plan include telemetry to track migration progress?
• Are there clear error codes (e.g., 410 Gone) for the sunset phase?
• Does it respect the {{sla_commitments}}?