Part IV — Engineering Under Supervision

This part is what separates a demo from something QA can sign. The engineering disciplines here — risk assessment, reproducible pipelines, app validation — generalize to any field where open source meets auditors, and they are the chapters non-pharma readers get the most from.

Chapter 9 reframes validation as risk-based reasoning rather than paperwork: you run a real package risk assessment and write the qualification memo QA actually expects. Chapter 10 rebuilds a clinical analysis as a targets pipeline that re-runs in minutes and replays exactly a year later. Chapter 11 takes a clinical Shiny app from rhino scaffold to a validation evidence file.

The habit to carry out of this part: validation is an engineering discipline you can learn and defend, not a tax you pay at the end.