Notes
Engineering write-ups from products we run in production. Specific problems, the approach we took, and the trade-offs we accepted.
Invalidating a graph of derived values with two counters instead of enumerating keys. A small technique that makes it structurally impossible to forget to invalidate something.
Event sourcing discipline without an event-sourcing framework — what it buys, what it costs, and the honest test for whether your domain actually needs it.
Sending a metered notification from a queue worker has three distinct failure modes, and retry logic fixes none of them. Modelling delivery as a row — claimed and budgeted in one transaction — fixes all three.
MCP servers, llms.txt, RFC 9727 API catalogues and well-known discovery documents — what we actually shipped to make a public data service consumable by machines, and which parts earned their keep.