Arcanum
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Embeddings · Level 3 · 7 min
How do I tune a threshold when I only logged the matches?
A similarity score was recorded every time two support cases were grouped and discarded every time they were not, so every number available for tuning was, by construction, above the threshold. The three near-misses that moved it were invisible until one column kept them.
Retrieval · Level 1 · 3 min
How do I get a model to answer from my own documents?
A model has never seen your documents, so asking it about them produces fluent, confident invention. The fix is not to teach it — it is to hand it the right passages at the moment you ask, which is the whole idea behind retrieval.
Evaluation · Level 2 · 4 min
How do you evaluate a retriever without labels?
Everyone agrees retrieval should be measured, and almost nobody has a labelled set to measure against. Twenty questions written by hand beat two thousand generated ones — a synthetic question is written from the passage it is meant to find, and shares its vocabulary in a way a real one never does.
Embeddings · Level 2 · 4 min
What similarity threshold should I use to group things by meaning?
Five support cases about the identical problem scored between 0.49 and 0.82 against each other, while unrelated pairs reached 0.66. The distributions overlap, so no single threshold separates them — and the system that got it wrong reported no error at all.
Context engineering · Level 2 · 6 min
How do you design a schema a language model can emit reliably?
An agent emitting JSON is the most demanding user your schema will ever have — no backspace, no documentation to consult, deciding mid-stream. Putting the contract in front of a model before you build anything behind it is the cheapest design review available, and almost nobody does it.
Agents · Level 3 · 5 min
How do you render UI an agent invented without trusting it?
An agent that returns interface instead of text is describing a tree your renderer will build. Everything upstream of that model — retrieved documents, tool output, other users' text — is now upstream of your DOM.