When we joined, it ran on .NET Framework, its parts talked over WCF, and much of the business logic was hidden in stored procedures. Every change took a long time and could easily break something.
Andor designed the architecture and the path of the modernisation, recorded the decisions in technical designs and ADRs, and had them approved by the client. Following that plan, we went step by step: in line with the strangler fig pattern, new modules gradually took over the work of the old code until a modular monolith took shape, its modules talking to each other through a mediator.
Andor also built the team: designed the hiring process and the take-home assignment, ran the technical interviews, reviewed the solutions and mentored new colleagues as the team grew.
The way of working followed Andor's lead too: an internal MCP server built for the project lets AI coding agents retrieve the relevant parts of the codebase and project context from a task's description, and the team used GitHub Copilot and Claude every day.
New modules came along the way. Access control was built as a reusable module and went into three of the company's other products; the reporting module loaded its data with Azure Data Factory. On these two modules we then built a new product from scratch.
We also replaced manual data entry from paper: a separate Azure Functions service used Azure OpenAI to read structured data from uploaded documents and write it straight into the database.