Jev Mode
Skills for Claude Code and Codex, and a study course, for building with Jev, TypeSafe's System One model. In the Ratings folder find the list of rated Jev projects and our eval methodology for user safety and quality.
Not every skill calls Jev: some are guides and LLM evaluators for building with it.
| Name | What it does | Calls Jev | Status |
|---|
| Jevaluate | Reads a Jev project's code and rates how well it uses Jev, with provenance for every finding | No: an LLM rates, and code checks the rating | Available |
| Jevaluate, privately | Rates a project you can't publish, such as a client's code or a local folder, with the same rubric, and keeps the rating private. Run /jevaluate-private <link or folder> | No | Available |
| Jevaluate Harness | Runs rating rounds, re-rates and rubric tuning for Jevaluate | No | Available |
| Jevaluate Eval | Tests whether Jevaluate's rubric leads graders to the right answers, before a rubric change reaches any rating | No | Available |
| Jev Sources | Finds the TypeSafe docs, patterns, cookbook and blog sections that answer a Jev question, by keyword and by meaning, and tells your coding agent (Claude or Codex) to read them before any claim | No | Available. Updated for Jev 1.14, including image input and Box questions |
| Jev Best Practices Study | A five-level course: summaries of TypeSafe's cookbooks and docs, then quizzes on the concepts and new glossary terms | No: a web course, nothing to install | Open the Claude artifact (recommended, Claude grades your definitions)Open in GitHub Pages |
| Jev Lens | Turns images into a neutral JSON state that Jev can read, one shared schema across the set | Only for an optional check of the finished state | Legacy. Don't use it: Jev reads images directly when a request sends the TypeSafe-Danger-Zone-Images: true header |
Take the course as the Claude artifact when you can: Claude grades your glossary definitions on meaning, while the GitHub Pages copy uses an untested keyword check.
How the Jevaluate skills work together, with diagrams: the system page.
Install
This repo is a plugin marketplace for Claude Code and Codex. It has three plugins:
jevaluate: the Jevaluate, Jevaluate Privately and Jevaluate Harness skillsjev-lens: the Jev Lens skilljev-sources: the Jev Sources skill and its hooks
In Claude Code:
claude plugin marketplace add tiffygk/jev-mode
claude plugin install jevaluate@jev-mode
claude plugin install jev-lens@jev-mode
claude plugin install jev-sources@jev-mode
After installing Jev Sources, ask your agent to refresh Jev Sources once: it runs refresh.sh --fetch, which downloads TypeSafe's docs, cookbooks and blog posts into ~/.claude/jev-sources-data.
In Codex:
codex plugin marketplace add tiffygk/jev-mode
codex plugin add jevaluate@jev-mode
codex plugin add jev-lens@jev-mode
codex plugin add jev-sources@jev-mode
Pull later changes with claude plugin marketplace update jev-mode or codex plugin marketplace upgrade jev-mode.
To install without the plugin system, copy a skill's folder into ~/.claude/skills/ for Claude Code, or ~/.agents/skills/ for Codex:
git clone https://github.com/tiffygk/jev-mode
mkdir -p ~/.claude/skills
cp -r jev-mode/jevaluate ~/.claude/skills/
cp -r jev-mode/jevaluate-private ~/.claude/skills/
cp -r jev-mode/jev-lens ~/.claude/skills/
cp -r jev-mode/jevaluate-harness ~/.claude/skills/
cp -r jev-mode/jevaluate-eval ~/.claude/skills/
cp -r jev-mode/jev-sources ~/.claude/skills/
cp -r jev-mode/shared ~/.claude/skills/
Any other coding harness that loads skills can run them with small changes.
Ratings of community Jev projects are in ratings/, released under CC0: use and change them freely.
Not affiliated with TypeSafe. The skills are licensed under PolyForm Noncommercial 1.0.0: free for personal and noncommercial use, with credit. Company or paid use needs a commercial license: open an issue.
