Week 7 (Blockchain track, Vyper): Low-scaffolding build, continued#

Goal#

Extend Week 6's project rather than starting a new one. Practice under low scaffolding before the safety net comes off entirely in Week 8. This is not new material.

Scope#

Add retry logic and idempotency to the backend service.
Handle a second event type from the contract.
Write a small test suite that would catch it if the service double-processed an event.

Note#

A learner who finds this week easy is ready for Week 8. A learner still fighting the tools here should stay another few days rather than move on.

Same project, still#

You're extending the exact backend service you built in Week 6, against the exact AssetRegistry contract from Week 5. Nothing new gets deployed. Nothing gets rewritten from scratch. This week adds robustness to a service that already works, which is a meaningfully different (and, for what it's worth, more true-to-real-engineering) task than building something new.

This week's outcome maps directly onto what the Week 8 acceptance-gate capstone will assume you can already do without re-teaching it: a service that sends transactions defensively, doesn't act twice on the same trigger, and can be trusted because you can point at a test that proves it.

Do this in order#

Steps 1-2 are required. Steps 3-4 are optional; skipping them leaves no gap in what Week 8 assumes you know.

notes/01-idempotency-and-retries.md through 03-organizing-under-more-weight.md, in order.
project/README.md's goal: retry logic, idempotency, a second event type, and a test suite that would catch double-processing. No numbered steps, on purpose.
Optional, before step 2, if idempotency or writing a real test feels unfamiliar: exercises/00-practice-seen-it-before.md and 01-practice-catch-the-regression.md, fake data only, no network.
Optional, after step 2: project/README.md's stretch goal, a processed-versus-skipped metrics counter and a third event type.