What it is
JevLoop is an open-source Python agent runtime for tool-using agents. Jev makes fast typed tool decisions, an LLM authors text and reviews low-confidence choices, and deterministic code owns execution, safety, durability, and state.
How it uses Jev
Jev decides operations and compatible targets via typed probability distributions compiled from mounted ToolSpec declarations. Code consumes only the target head matching the selected operation. Low-confidence decisions escalate to an LLM review; Jev may also bind observation references or choose LLM_PARAMETERS.
Primitives:choice
Technique worth stealing
Compile tool specs into one Jev request with an operation question plus speculative target questions, consuming only the compatible target head.
Try it
cd backend && uv sync && uv run jevloop smoke
Evidence
Each line is one question put to Jev about the README. ≥ 0.60 reads as yes, ≤ 0.40 as no; in between Jev is not making a call.
- Jev-centricyes0.96
- Shows a System One patternyes0.94
- Handles uncertaintyyes0.80
- Measuredno0.05
- Runnableyes0.84
- Worth recommendingyes0.62
- Model replicano0.06
- Problem scopescore on a 0–2 scale1.66
- About Jevyes0.98
Signals by Jev jev-1.13.0, card written by DeepSeek V4.1 Flash from the README on 23 Sept 2026.