Even the smallest change in the bank's mobile app - a new loan application flow, a simple campaign screen, a button moving place - was tied to core banking's quarterly release windows, and business demands went stale before they shipped. Integrations between the channels and the core had no contracts; what would break only became visible in production, while customers were using the app.

After an assessment spanning nine focus areas we started the decoupling at the architecture: channels now reach the core through versioned service contracts, behind an API layer. We built the channel teams their own delivery line: trunk-based development, contract and regression tests on every commit, and one automation chain from demand to production, approval flow included. The same team built the architecture, wrote the code and shipped it.