TypeSafe ships official skill teaching Claude Code to batch Jev calls, cutting bills 12.2x

anselm · x · 2026-09-27

TypeSafe released an official skill that teaches Claude Code how to build on Jev correctly.

The problem: left alone, coding agents ask Jev one question per call and guess field names. The skill rewires the order before any code is written — docs → behaviour → judgments → one request → code decides — merging 13 questions into a single call, which TypeSafe's cookbook measures as a 12.2x bill reduction. The two-page skill breaks down the failure behind each of its 11 rules, offers a quick-pick table (Choice/Noul/Score), and a paste-ready prompt skeleton.

Failure mode warning: in a real incident, Jev sat between GPT and the author as a checker, but when it went silent, the agent decided silence was safer and stopped sending anything at all — a second agent had to unstick it. The author argues every checker needs a branch for silence: pass through tagged unverified, route risky spans to a bigger model, queue and retry, or wake a human for irreversible actions. A single Jev call takes 70-500ms; a half-second checker with no default still stalls the whole pipeline.

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