Architectural Evolution and Refactoring Questions

Discuss leading large scale refactoring and architectural evolution efforts. Candidates should describe criteria for when to refactor versus rearchitect, incremental migration strategies that reduce risk, approaches for preserving backward compatibility and managing breaking changes, data migration techniques, and testing and rollout strategies such as staged deployments and canary releases. Cover coordination across teams, rollback and recovery plans, and how to measure the impact of architecture changes on velocity, reliability and maintainability. Interviewers evaluate pragmatic judgment, planning, and risk mitigation.