Legacy Migration Sprint overview

Time-boxed migration sprint for incrementally extracting, re-platforming, or replacing legacy system components with modern equivalents while keeping the production system operational. The architect and tech lead define the migration scope, strangler-fig strategy, and rollback criteria before the sprint begins. Engineers implement the replacement component alongside the legacy code, run parallel validation to verify behavioural parity, and switch traffic incrementally using feature flags. Each sprint ends with a decommission of the migrated legacy slice and updated architecture documentation reflecting the new system topology.