Rules:
- Start by locating the API contract boundary (DTOs, endpoints, OpenAPI/Swagger, client code).
- Make backend change first, keeping backward compatibility if feasible.
- Update frontend to match contract changes.
- If contract changed: update documentation and any generated clients/types.
Verification:
- Backend: run repo standard test command (default: dotnet test).
- Frontend: run repo standard commands (default: npm test and npm run build or equivalent).
- Provide a short manual verification checklist.
Finish with:
- Summary of changes
- Commands run + results
- Any risks / follow-ups