Lesson 5: Evaluate the whole system, then keep it honest
26 min read·13 Oct 2026
Module 10 · Lesson 5 · About 50 minutes · Needs: Lesson 1 (cases,check, the regression suite); Lesson 2 helps (intervals, paired comparison); Module 5 Lesson 1 (decide)
The situation
It is Wednesday 12 August 2026, week 11. Yesterday Ravi approved a German draft for T-1187, from the admin of Brandt Logistik, whose annual plan renewed 30 days ago: "Sie erhalten eine volle Rückerstattung innerhalb von 5 bis 10 Werktagen." Joel refused the refund, so no money moved, but the customer was promised it. Maya apologised this morning.
Maya asks three things. Which part of the assistant got it wrong? Why did the eval suite not stop it? And how do we make sure it never ships again? This lesson answers all three, with T-1187 as the running example.