CodeTwo roads
Big-bang: freeze the old system, build the new one in parallel, cut over on a big day. Strangler-fig: grow the new system around the old one, replacing it piece by piece until the old one can be removed.
Big-bang is seductive and dangerous. The cutover day slips, the parallel build drifts from the moving original, and the whole bet rides on one release.
Why strangler-fig wins
Incremental migration keeps you shipping the whole time, limits the blast radius of any mistake to one slice, and lets you learn as you go. The catch: you need to know the dependencies, or you'll strangle the wrong thing first.
Dependencies, mapped
CodeIQ Pro carves the app into dependency-safe slices and orders them least-depended-on first — so you migrate leaves before trunks and never pull the rug out from under code you haven't moved yet.
Proof at every step
Each slice migrates against a known contract, and the parity gate verifies the new code preserves it. Strangler-fig stops being an act of faith and becomes a sequence of verified, reversible steps — modernization you can defend to the board.