Overview
What this challenge is about.
Read the current Go webhook-sender code and 30 days of duplicate-delivery incident logs. Design the idempotency scheme: server-generated key per event (UUID v7 — time-ordered), an idempotency table in Postgres with at-most-once semantics, a delivery-deduplication window of 24 hours. Implement the sender, the storage, and an HTTP middleware merchants can use for safe receive. Write a chaos-test harness simulating network retries, partial failures, and merchant-side restarts. Prove zero duplicate side-effects across 100k simulated events. Deliver the Go implementation, the chaos-test report, an updated OpenAPI spec with the Idempotency-Key header documented, and a 4-page merchant migration guide.
The Brief
What you'll do, and what you'll demonstrate.
Design and implement an end-to-end idempotency-key mechanism for the merchant webhook system that proves zero duplicates under realistic retry storms.
Earning criteria — what you'll demonstrate
- Design an end-to-end idempotency scheme for a payment system
- Implement at-most-once semantics with Postgres-backed storage
- Validate idempotency under chaos-test conditions
- Communicate a public-API contract change to external partners
Program Fit
Where this fits in your program.
Sharpens the same skills your degree expects you to demonstrate.
Skills
Skills you'll demonstrate.
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Careers
Roles this prepares you for.
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Career mappings coming soon.