Driftless field notes
Practical guides for LLM workflows that move.
Model deprecations, changing labels, cheaper inference, RAG, and agents. Each guide shows how to keep the model, prompt, and eval data in sync with a reproducible example.
You run a support product that routes every inbound ticket through an LLM classifier before a human ever sees it. The model returns a small JSON object like {"category": "billing"}. Downstream code parses that JSON…
Same support classifier as post 1: every ticket gets a gold category so you can measure quality offline. For a long time, tickets like "Please reverse the payment on my latest invoice" are labeled billing — the team…
Read guide → Prompt repair that doesn’t wait on memoryYour LLM app already looks "done" from a git perspective: prompts live in the repo, gold labels live in JSONL, and a harness command can score quality offline. You can migrate a model or refine after a label change…
Read guide → Finance wants cheaper inference, same barYour classifier (or similar LLM workflow) runs on a frontier model — say gpt-4o — because that is what cleared quality when you launched. Volume grew. Finance now wants 20%+ inference savings. A cheaper model like…
You trust your offline eval. Macro-F1 on a few hundred labeled tickets is how you decide whether a model migration or prompt refine is safe. After a labeling policy change (or a messy annotation pass), you run…
Read guide → Free-form answers graded by an LLM judgeNot every LLM workflow is a classifier with gold categories. You might summarize support tickets, rewrite answers for tone, or grade free-form responses for faithfulness. There is no single label_field to compute…
You ship a retrieval-augmented QA feature: user asks a question, the app retrieves chunks from a knowledge base, and an LLM writes an answer that should stay grounded in those chunks and cite them. Quality is…
Read guide → Tool-calling agent: new planner, same toolsYou run a support-style agent that must use tools — look up an order, check a policy, create a ticket — before it answers the user. Success is not only a polite final message. The agent must call the right tools in a…
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