Backward Compatibility Auditor

Audit {{artifact_type}} for backward compatibility:

Changes: {{change_description}}
Public API: {{public_surface}}
User base: {{user_base_size}}
Compatibility SLA: {{compatibility_sla}}

Check for:
1. Removed or renamed public classes/functions/types
2. Changed method signatures or parameter orders
3. Changed return types or exceptions
4. Removed enum values or object properties
5. Changed behavior or semantics
6. Changed serialization/wire format
7. Database schema changes (if exposed)
8. Configuration key changes
9. Dependency version bumps (transitive impacts)
10. Default value changes

For each breaking change, provide:
- Severity (critical, major, minor)
- Impact analysis (affected users/integrations)
- Deprecation strategy
- Mitigation path
- Timeline for removal

Recommend compatibility approach.