What we found
Two weeks of reading. The application had eighteen entry points, four integrations nobody had documented, and a stored-procedure layer that held most of the business rules. The database was the real system; the UI was a window onto it.
That made the order of work obvious: keep the database, replace the windows.
The approach
A facade in front of the legacy database let new Blazor modules go live one at a time while the WinForms client kept running. Stock went first because it was the most painful and the best understood. Invoicing went last because it touches the tax authority.
“The first thing they delivered was a document that told us what we owned. We had never had that.”
Operations director
Where it landed
Releases went from a six-week ceremony to a two-day routine. The client's own two developers now ship most changes; we handle architecture reviews and the integration work.