Session 15. Defend the capstone — Fri 02 Oct

Quick quiz (ungraded)

Q1: The judge draws the tampered-bytes card, and your buyer prints `STOP` at verify instead of `NO`. What is the best answer?

Run it again until it says NO
A refusal that appears on the third attempt is evidence about the first two.
Read the line: STOP means a step could not reach what it needed. Say nothing was submitted, and switch to the recorded lane
Correct. Nothing was sent either way, and naming the difference between STOP and NO is the diagnosis being judged.
Say the network is flaky and move on
It might be. But the room heard a claim you did not show.

Q2: What makes an architecture decision defensible?

A benchmark showing the chosen option is faster
Useful, but a benchmark is the evidence, not the decision.
Naming the measurement or event that would reverse it
Correct. A decision with no reversal condition is a preference wearing a decision's clothes.
Following the approach the course used
Then it is the course's decision, not yours.

Q3: Your buyer printed `submit ... slot 506053275`. Is that proof the purchase landed as asked?

Yes, a slot means it confirmed
It means something confirmed. It does not say what moved, or to whom.
Only with the receipt: two ledger reads, the deltas, and total_purchases going from n to n+1
Correct. The ledger, read before and after, is what says what moved.
Yes, if the explorer link opens
The link shows the transaction exists, not that it matches what was pinned.

Q4: Which of these is NOT evidence that your buyer works?

A refusal file naming the field and both values
That is evidence.
A receipt with the ledger deltas and the explorer link
That is evidence.
A polished interface and a smooth run-through
Correct. Evidence is what your repository and your buyer's output show, not polish.