# Mellow AI: mev

> Mellow AI's Jev-inspired decision model: a fine-tune of Qwen3.5-4B on Together's open Tev1 recipe that reads a state, a question and 2 to 24 options and returns one option letter. Option probabilities come from the first generated token.

- Page: https://systemonemodels.ai/mellow-ai/mev
- API: https://api.systemonemodels.ai/v1/models/mellow-ai/mev
- Download: `pip install systemonemodels && systemone pull mellow-ai/mev`

## Facts

| | |
|---|---|
| Maker | Mellow AI (https://systemonemodels.ai/mellow-ai) |
| Decides | choice, noul, classify, route |
| Architecture | mev |
| Base model | qwen/qwen3.5-4b |
| Parameters | 4.0B |
| Licence | apache-2.0 |
| Availability | Open weights |
| Released | 2026-09-25 |
| Latest version | 2026.09 |

## Reported evaluation

Suite: Tev1 recipe main decisions development set (1,000 decisions; shaped the recipe, not held out), Mellow AI's own run. Numbers are the publisher's own.

- Decision accuracy: 86.7%
- Calibration error (ECE): 0.038

## Model card

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# mev

Mellow AI's Jev-inspired decision model: a fine-tune of Qwen3.5-4B on Together's open Tev1 recipe that reads a state, a question and 2 to 24 options and returns one option letter. Option probabilities come from the first generated token.

It keeps the language-model head and emits a single option letter, so it is Jev-inspired rather than a non-autoregressive decision head, the same approach as Together's Tev1; the card says it does not reproduce Jev's runtime and was not trained on Jev outputs. A rank-8 LoRA on all linear modules, one epoch on the 37,840-example Tev1 recipe mixture, published merged. The maker's numbers are on development sets reused from that recipe, not held out: 86.7% on the main decisions set against Tev1's 88.0% on the same set, with ECE 0.038. Yes/no maps to two options; score is computed client-side. English only; no hosted API. Training-data sources keep their own terms.

## What it decides

- **choice** — picks one option from a set
- **noul** — answers a yes/no question with one probability
- **classify** — assigns a category from a fixed taxonomy
- **route** — sends the input to one of several destinations

## At a glance

| | |
|---|---|
| Parameters | 4B |
| Base model | `qwen/qwen3.5-4b` |
| Maker | Mellow AI |
| Released | 2026-09-25 |
| License | apache-2.0 |
| Reported accuracy | 86.7% |

## Get the weights

```bash
pip install systemonemodels
systemone pull mellow-ai/mev
```

The files are served from the maker's Hugging Face repository, [`stay-mellow-ai/mev`](https://huggingface.co/stay-mellow-ai/mev), and verified against the checksums recorded here.

## Read more

- [Model card](https://huggingface.co/stay-mellow-ai/mev)

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