Incremental migration pattern popularised by Martin Fowler. Instead of a big-bang cut-over, a proxy or routing layer is introduced in front of the old system and functionality is migrated piece by piece, 'strangling' the legacy system until nothing is left. Recommended by Chikahiro Tokoro for rolling out modular-monolith refactorings without downtime; he points to a Shopify blog post as a real-world worked example with real code.