aistwin https://aistwin.online/ Notes on building a personal AI assistant that answers from my own notes. en Evaluating answers without fooling myself https://aistwin.online/posts/evaluating-answers/ https://aistwin.online/posts/evaluating-answers/ Thu, 29 Oct 2026 18:00:00 +0000 It's easy to feel that answers got better after a change. A small, boring test set tells me whether they actually did. SQLite is enough for vector search at my scale https://aistwin.online/posts/sqlite-is-enough/ https://aistwin.online/posts/sqlite-is-enough/ Mon, 19 Oct 2026 18:00:00 +0000 Twenty thousand chunks, 384-dimensional embeddings, brute-force cosine similarity. It takes 9 milliseconds. I don't need a vector database. Chunking notes for retrieval: what actually mattered https://aistwin.online/posts/chunking-notes/ https://aistwin.online/posts/chunking-notes/ Thu, 08 Oct 2026 18:00:00 +0000 I tried fixed-size chunks, sentence windows and heading-based splits. Headings won, by a lot, and the reason is obvious in hindsight. Why I'm building a twin instead of using a chatbot https://aistwin.online/posts/why-a-twin/ https://aistwin.online/posts/why-a-twin/ Sun, 27 Sep 2026 18:00:00 +0000 General chat assistants know everything except the things I actually need. So I'm building a small one that only knows my own notes.