Top Repos· OSS alternatives· Eval· Last updated 2026-09-21

mithalouni / system-one-open

OSS alternative — not TypeSafe Jev. This is a public GitHub System One–class / typed-decision replica. It is not Jev and not endorsed. Closed or no-repo competitors stay on Comparisons.

“Open replica of TypeSafe's Jev: typed calibrated decisions in one forward pass, on Gemma 4 E2B / Gemma 3 270M (Modal)”

OSS alternatives rank #26In Eval #26

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TL;DR

mithalouni/system-one-open is an independent System One–class decision engine or interface clone. Useful to study. Not TypeSafe Jev, not RLCD, not a calibration transfer.

The author describes it as: “Open replica of TypeSafe’s Jev: typed calibrated decisions in one forward pass, on Gemma 4 E2B / Gemma 3 270M (Modal)” That is their claim, not a bench this site ran.

Who it’s for

• Researchers comparing a local or open decision engine to hosted Jev — never as a silent substitute
• Anyone who needs the unofficial line: jev.pro does not issue keys and is not TypeSafe

What’s inside

Top-level entries on GitHub at generation time: .gitignore, LICENSE, README.md, build_data.py, build_emails.py, demo_client.sh, emu_check.py, evaluate.py, games.py, hf_upload.py, make_report.py, mario_data.py, media, report.html. Read those before you trust a one-line install.

How to use

1. Clone and follow the author’s Python toolchain. Do not invent a package name.

git clone https://github.com/mithalouni/system-one-open.git
cd system-one-open

2. If you compare to Jev, keep a processor label so replica rows never read as Jev scores.
3. Send a complete state and typed questions. Code owns control flow after the probabilities.

This repository is not TypeSafe Jev. Hosted Jev, for comparison only, still looks like a function call:

{
  model: "jev-1.13.0",
  state: { source: "mithalouni/system-one-open", brief: "..." },
  questions: {
    gate: { type: "noul", instructions: "Should we act on this state?" },
    route: { type: "choice", instructions: "Pick one next system.", criteria: ["code", "review", "human"] },
  },
}

Try this

Label a side-by-side, do not merge floors

Compare mithalouni/system-one-open and hosted jev-1.13.0 on my 50 labeled tickets. Report agreement. Do not copy thresholds. Tag every row with processor=replica or processor=jev.

Schema-safe ≠ correct

On a case mithalouni/system-one-open gets wrong, write down the schema-legal answer it returned and the human label. Do not “fix” it by asking Jev to generate an explanation.

FAQ

Can I treat these scores as Jev?

No. Label them as replica or local-engine results. Calibration does not transfer.

Does TypeSafe endorse it?

Their public docs index does not list it as Jev. We do not either.