jev-dev: A UI Tool to Keep Run History When Experimenting with Jev

Melvin Vivas · X post · 2026-10-01 · Open on X

Topics: AI Dev Tools & Productivity, Prompt & Context Engineering · Level: intermediate

Summary

Melvin Vivas built jev-dev, an open-source UI tool for experimenting with Jev by Typesafe.ai. He built it because the Jev Playground doesn't keep a history of past runs. An experiments feature is still being built.

Key points

• The Jev Playground doesn't save a history of past runs.
• jev-dev (github.com/donvito/jev-dev) is a UI tool for experimenting with Jev by Typesafe.ai and keeps track of past runs.
• An 'experiments' feature is still in progress.
• Pattern: when a vendor playground lacks run history, a small local UI that logs prompts and outputs makes iteration easier.

Resources mentioned

• donvito/jev-dev · repo · github.com · free
  UI tool for experimenting with Jev by Typesafe.ai that keeps a history of past runs.
  Also in: Generating a Repo Promo Video with a Claude Skill on Sonnet 5.5 vs Opus 5.5 (Melvin Vivas on X · notes), JevDev: Open-Source UI Tool for Experimenting with Jev (Typesafe.ai) (Melvin Vivas on X · notes), JevDev: Open-Source UI for Experimenting with Jev by Typesafe.ai (Melvin Vivas on X · notes)
• Jev (TypeSafe AI) · tool · typesafe.ai · free
  TypeSafe's new post-training algorithm for calibrated, confidence-scored decisions, pitched as a replacement for RLHF.
  Also in: JevDev: Open-Source UI Tool for Experimenting with Jev (Typesafe.ai) (Melvin Vivas on X · notes), JevDev: Open-Source UI for Experimenting with Jev by Typesafe.ai (Melvin Vivas on X · notes), Building a Jev Session-History Tool with Codex and Astra (Melvin Vivas on X · notes), Model Routing: Fine-Tune Your Own Router on Your Prompts (Melvin Vivas on X · notes) and 7 more

Try this

• Try the jev-dev repo if you experiment with Jev.
• Build a small UI on top of an AI tool's playground that saves and compares the history of past runs.