---
license: apache-2.0
tags:
  - yev
  - decision-model
---

# yev

The client for [Yev-Decision-1](https://huggingface.co/HallD/Yev-Decision-1), a local **System One**
decision model. Give it a state, which can be text, images or both, plus named questions. It returns
a typed probability distribution for each one: a **Choice** between options, a **Score** on an
ordered scale, or a **Noul** (yes or no). It generates no text and nothing leaves the machine.

## Install

```sh
uv add "yev[inference] @ git+https://huggingface.co/HallD/yev"
```

`pip install "yev[inference] @ git+https://huggingface.co/HallD/yev"` works the same way. Python 3.13
or later.

| Extra | Brings | For |
| --- | --- | --- |
| *(none)* | pydantic, huggingface-hub, numpy | Question and answer types only |
| `inference` | torch, transformers, peft, accelerate, pillow | Answering questions with a model |
| `quantized` | `inference` plus bitsandbytes | `quantize4bit=True` on a CUDA GPU |

## Use

```python
from yev import Choice, Image, Noul, Score, YevClient

with YevClient() as client:   # YEV_DEFAULT_MODEL, else HallD/Yev-Decision-1
    response = client.system_one(
        state="I was charged twice. Please fix this ASAP.",
        questions={
            "billing": Noul(instructions="Is this ticket about billing?"),
            "tone": Choice(instructions="What is the customer's tone?",
                           criteria={"calm": None, "frustrated": None, "angry": None}),
            "urgency": Score(instructions="How urgent is this ticket?",
                             criteria=["can wait", "this week", "today"]),
        },
    )
print(response.nouls["billing"].noul, response.choices["tone"].probabilities)
```

The first call downloads the model and its backbone,
[`Qwen/Qwen3.5-4B-Base`](https://huggingface.co/Qwen/Qwen3.5-4B-Base) at a pinned revision, into the
Hugging Face cache. After that it runs offline (`HF_HUB_OFFLINE=1`). The backbone runs in bfloat16;
its weights and the adapter take about 10.4 GB.

The call shape follows the TypeSafe SDK (0.7.5): `YevClient` and `AsyncYevClient` take its
`system_one(state, questions, model=, assets=, response_model=)`, its question objects (TypeSafe's
own are accepted), and return its answer and response types. It runs in-process, so there are no
API keys, retries or timeouts; Box questions are refused, and a Score takes at most 10 levels.

`yev --export HallD/Yev-Decision-1 --state "I was charged twice." --noul billing "Is this ticket about billing?"`
asks from the command line.

## JevBench

`examples/jevbench_adapter.py` is an adapter for the
[JevBench](https://github.com/fstandhartinger/jevbench) harness: it sends the harness's own question
to `system_one` and returns the probabilities, with the input tokens the model read as `usage`
(output tokens are always 0).