Chapter 46 — Engineering capstone II
Lesson map
Lesson 46 published. Map, example, EX091.
flowchart TD
N0["Learning outcomes"]
N1["46.1 Scope of Capstone II"]
N2["46.2 Verification and validation"]
N3["46.3 Agility demonstration"]
N4["Engineering note"]
N5["46.6 Handing the capstone to operations"]
N6["Synthesis"]
N0 --> N1 --> N2 --> N3 --> N4 --> N5 --> N6
N6 --> EX["Worked example"]
EX --> Q["Exercise EX091"]
Logical drawing
flowchart LR
N0["Learning outcomes"]
N1["46.1 Scope of Capstone II"]
N2["46.2 Verification and validation"]
N3["46.3 Agility demonstration"]
N4["Engineering note"]
N5["46.6 Handing the capstone to operations"]
N6["Synthesis"]
N0 --> N1 --> N2 --> N3 --> N4 --> N5 --> N6 --> Q["EX091"]
[Learning outcomes]
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[46.1 Scope of Capstone II]
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[46.2 Verification and validation]
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[46.3 Agility demonstration]
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v
[Engineering note]
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v
[46.6 Handing the capstone to operations]
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[Synthesis]
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[Worked example] --> [Exercise EX091]
Learning outcomes
You will (1) complete the capstone implementation across domains; (2) execute verification and validation; (3) demonstrate agility; and (4) prepare evidence for the dossier. It follows the review of Chapter 45.
46.1 Scope of Capstone II
Complete hybrid key exchange on edge and partner VPNs (or interim PSK where appliances lack support), dual-signed bills of lading with timestamps, dual-recipient customs exports, CBOM coverage ≥ 95% with unknowns reported, and an agility demonstration.
Each item continues work begun in Capstone I and is measured against its baseline. The 95% CBOM coverage target matches REQ-INV-01, so the capstone tests the same requirement as production. The agility demonstration is included because it is the one item that shows the system can change again after the capstone ends.
46.2 Verification and validation
Run Verification Laboratories I and II test suites against the completed system; collect partner acceptance; produce the residual-risk statement. Address every review finding with evidence.
The suites from both verification laboratories are run unchanged, so results can be compared with the earlier runs. Partner acceptance is collected per partner with dates. The residual-risk statement lists what remains classical and when it will change. Every review finding from Capstone I needs evidence of its resolution; an open finding prevents completion unless the risk is explicitly accepted by the programme owner.
46.3 Agility demonstration
Demonstrate replacing one algorithm through policy within the target time — for example, switching the edge's preferred hybrid group from X25519MLKEM768 to SecP256r1MLKEM768 for a compliance scenario, then back, measuring time-to-replace and confirming telemetry follows.
Switching and then switching back proves that the change is reversible and that telemetry tracks it in both directions. The timer starts at the policy change request and stops when telemetry shows the new group negotiated by all clients that support it. Any manual step needed along the way is recorded, because each one is a place where a real emergency change could stall.
46.4 Worked example
Model results: edge hybrid share 71%; VPNs — 9 of 14 partners with ML-KEM additional key exchange, 5 with PSK mixing; bills of lading dual-signed since month 14; exports dual-recipient, agency acceptance pending; CBOM coverage 96%, unknown 4%; agility demonstration: policy change to full negotiation in 3 days.
The figures are consistent with earlier stages: edge hybrid share rose from 64% to 71%, CBOM coverage from 94% to 96%, and the VPN split matches the decision table's interim PSK option for older appliances. The agency acceptance remains pending and is reported as such.
46.5 Common errors and limits
- Claiming completion with unresolved review findings.
- Agility demonstrated only on a test bench.
- Residual risk omitted.
Claiming completion with open review findings hides known problems from the people who will operate the system. An agility demonstration only on a test bench does not prove the production pipeline can change algorithms, so it runs in the replica environment with production configuration. Omitting residual risk leaves operations unaware of what still needs attention after handover. The handover to operations later in the capstone depends on all three being right.
Engineering note
Capstone II is also the moment to rehearse handover. Write the operations runbook, the CBOM maintenance procedure and the agility procedure as if a different team will run the system tomorrow, then ask a peer who did not work on the project to perform one routine task — rotating a fallback expiry, adding a partner, changing the preferred group — using only the documents. Every question they ask marks a gap to close before the dossier is assembled.
46.6 Handing the capstone to operations
The Capstone II package goes to BPA's operations team with the configuration changes, the test evidence, the rollback steps and a list of what remains classical and why. An operations engineer replays the agility demonstration without the student present; only when that replay succeeds does the capstone count as transferable rather than a one-person result, and any step that needed the student's help is rewritten.
The replay also tests the runbook's assumptions, such as access rights the student had but operations staff lack.
Exercises
- EX091 — Agility demo plan. Write the agility demonstration plan with success criteria. Rubric: 3 = start/end events, telemetry evidence, rollback.
- EX092 — Findings closure. Produce a findings-closure table for Chapter 45's review. Rubric: 3 = each finding with evidence of closure or accepted risk.
Synthesis
Capstone II completes the migration increment by increment, verifies and validates it, demonstrates agility and closes review findings with evidence.
Continue studying — chapter 46 of 50
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