Designs by Duhart
Writing Bugs that were interesting, and the reasoning that found them. Every post here comes out of something that actually ran in production. No post is a tutorial for a thing I have not done.
15 September 2026 8 min Breach Protocol: a Transformer You Can Read, Running on the Codes You Type I wrote a small Transformer in C++, taught it a trick in 85 seconds, compiled the same code to run in your browser, and drew what it thinks in 3D. Here is how, in plain words. MachineLearning SoftwareEngineering SystemDesign WebAssembly 5 September 2026 4 min The working directory is part of the deploy A build that passes, a deploy that exits zero, and a site that serves every page while its API returns 404. The fault was in neither the build nor the deploy. It was in where they ran. Cloudflare Pages CI/CD wrangler 24 August 2026 3 min The outbox is not a queue A Cloudflare Worker cannot open a TCP socket, which sounds like a limitation and is actually a design forcing function. What it forced, and what it cost. Go Kafka Postgres edge 18 August 2026 3 min Cassandra UPDATE is an upsert, and it cost us a phantom partition per user A ranking loop wrote scores using the region it was iterating rather than the region the row lived in. In a relational database that is zero rows affected. In Cassandra it is a new partition. Cassandra Go data modeling 11 August 2026 3 min 952 messages nobody was ever going to read A Redis consumer group's pending-entries list had been growing for weeks. Nothing was broken, no alert fired, and every message in it was permanently stuck. Redis Go operations