Lab: Traces, replay and alerts for every run

Module 14 · Lab · About 80 minutes · Needs: the Module 3 lab's tools.py, lessons 1 (tracing, cost, logs, OpenTelemetry) and 2 (replay, diffs, alerts)

What you are building

It is Monday 22 June 2026, week 11 (simulated). Dev's prompt change for tomorrow is ready and will skip the eval gate; trace it before it ships. This lab moves both lessons' code into returns_desk/tracing.py: Lesson 1's tracer around Module 5's loop, with tokens, cost and time per span, the JSON Lines log, Lesson 2's replay, first divergence, diff and alerts, and an OpenTelemetry exporter. Tool calls still go through Module 3's call. You follow Aisha's R-1001, then her kettle request, R-1003, under tomorrow's change. Everything is simulated.