Notes on software engineering, system design, and the craft of building.
New payment confirmation code ran in production on Joytop for a week in shadow mode — deciding nothing, only watching. Tomorrow it becomes the one that decides. What shadow mode actually does, what it protects against, and why you can't turn it on without watching it.
Stanford tracks the payroll of five million Americans a month. Employment for 22-to-25-year-olds in AI-exposed jobs sits nineteen percent below where it should be. Nobody is being laid off — they are simply not being hired. Those are entirely different problems.
A retry is not a duplicate request — until it is. How idempotency keys actually work, why the naive version still double-charges, and the exact Postgres constraint that makes the guarantee real.
A 27-year-old pretraining researcher quit Anthropic this week, saying the industry is 'gambling with our lives.' He is the second senior departure this year. What the pattern actually tells us — and what it doesn't.
Prompt engineering was about wording. Context engineering is about deciding which tokens deserve a place in a limited window — and it is now the skill that separates agents that work from agents that almost work.
Strip away the marketing and an agent is a loop with three parts. Understanding those parts tells you exactly why agents fail in production — and which of the failures are worth fixing.
Node 24 strips types at runtime, so `node server.ts` just works. That is genuinely useful — and it is not the same thing as Node supporting TypeScript. Here is where the line actually falls.
The joke says it's one of the two hard problems. The reality is that most teams never write an invalidation strategy at all — they write a TTL and hope. Here is what the alternatives actually cost.
