I set out to have a language model classify integration failures. I built an evaluation harness to prove it worked. The harness proved it wasn't worth using.

Final architecture: deterministic rules do the classification and structured extraction. The LLM does exactly one thing, writing plain-English incident summaries. Cheap rules to sort, AI to explain.

Harness is here: https://github.com/fissible/llm-triage-eval

Here are the numbers, then how I got them.

The headline