Implementing a Multi-Channel Payment Callback Framework: Unified Entry, Verify Adapters, and Compensation
Write one callback endpoint for the first channel and it is thirty lines. Copy it for the second. By the third the code has spiraled: verification logic scattered, response formats diverging, idempotency reimplemented three ways, and lost notifications untraceable. This article lays out a reusable framework with a unified entry point, verify adapters, an idempotency middle layer, and scheduled query compensation.