Executable capacity envelopes and assumption sensitivity

This required 20–30-hour package strengthens guided Labs 2–3: lessons/predictions 5–7 hours, implementation and experiments 9–15, assessment/repair 6–8. Reuse outputs in the original design packet; do not count the same calculations twice. Estimates await semester reconciliation and learner pilots.

Prerequisite bridge

Review dimensional analysis, fractions, ceiling and conservation from foundations; backlog/failure behavior from systems; and Semester 07 claim/evidence discipline. Distinguish offered, admitted, completed and rejected work. Bring the prior semester's scenarios, ownership map and unresolved risks.

Sequence

1. Unit contracts.
2. Burst and backlog.
3. Assumption sensitivity.
4. Implement capacity-envelope-contracts.zip in Python 3 standard library. Run python3 -B check.py starter before reference calibration.
5. Complete SD1–SD6.

The finite harness checks 2,916 queue traces with an independent object-queue oracle, 945 sizing cases using feasibility/minimality inequalities, conservation, input preservation and invalid inputs. It does not simulate individual latency, network behavior, retries or realistic failure placement. Preserve original timed design, two deep dives, full read/write failure walkthrough and review-ready document. The 45-minute exercise is a framing drill, not a production design certification.