Kingpin

The build log

Real bugs, real incidents, and the design calls behind Kingpin — written up as they happen, dead ends included, not cleaned up after the fact.

• Sep 15, 2026

  A cache with no way back to the source

  A founder's own paid listing showed no usable name in their own dashboard — the story of a denormalized field nobody remembered to keep in sync.

  dynamodbdata-design

• Sep 15, 2026

  A variable that looked in scope, and wasn't

  A one-line fix that compiled, passed lint, and threw ReferenceError the instant a real browser touched it — plus a card with a mysterious hole in the middle.

  frontendreactdebugging

• Sep 14, 2026

  Two mechanisms that look redundant, and why only one of them was

  Decay and downvotes look like they do the same job. They answer different questions — and nearly deleting one would have silently killed a revenue model.

  productranking-design