#architecture

The queue, the cache, the search index, the vector store, the job scheduler and the analytics table for a product with 40,000 daily users all live in one Postgres 18 instance. That is not a compromise. It is the design. Here is what each piece looks like, what it costs, and the three specific signals that would make me move one of them out.

A client asked me to take over a product that had been built in four months by two people and an agent. It worked. Sixty thousand lines, no human had read most of them, and the first bug took a week to find because there was nobody to ask. This is what it is like to inherit vibe coded software, and what I would have done differently in the four months.

A million token context window did not make the long-running agent problem go away. It moved it. The model still forgets the thing you told it an hour ago, only now it forgets it after paying for it forty times. The techniques that work, compaction, retrieval, memory files, all turn out to be the same techniques we use to manage a cache.