Gradient AI Text Detector, ONNX (fp32 + fp16 + q4)

ONNX exports of ShantanuT01/gradient-ai-text-detector, a DeBERTa-v3-large binary classifier producing P(AI). Built for transformers.js so the model can run in a browser with no server.

q4 is the default: weight-only 4-bit, so it is both half of fp16 and within 0.06 of the reference, with no verdict flips at a 0.5 threshold across the 12 fixture passages. Use fp16 when closer-to-exact scores matter more than download size.

An int8 build (onnx/model_quantized.onnx, 612 MB) previously shipped here and was removed. Dynamic int8 drifted 0.30 mid-range: larger and roughly five times less accurate than q4. Its error comes from quantizing activations, which is also why calibrated static int8 measured worse still (0.63-0.99).

Usage

import { AutoModelForSequenceClassification, AutoTokenizer } from '@huggingface/transformers';

const repo = 'batmac/gradient-ai-text-detector-onnx';
const tokenizer = await AutoTokenizer.from_pretrained(repo);
const model = await AutoModelForSequenceClassification.from_pretrained(repo, { dtype: 'q4' });

const text = "In today's rapidly evolving digital landscape, organizations must leverage synergistic strategies.";
const inputs = await tokenizer(text, { padding: true, truncation: true, max_length: 512 });
const { logits } = await model(inputs);
const pAi = 1 / (1 + Math.exp(-logits.tolist()[0][0])); // sigmoid

num_labels is 1: the model emits a single logit and the caller applies sigmoid. Do not use the text-classification pipeline, which applies softmax to that single logit and returns score: 1 for every input.

Export and quantization

Exports were produced with optimum at opset 17, dynamic batch and sequence dims, inputs input_ids and attention_mask only. fp16 is a straight convert_float_to_float16 with keep_io_types.

q4 composes three steps, all weight-only, so activations stay at higher precision:

1. MatMulNBits int4 (RTN, group size 32) for the matmuls;
2. quantize_dynamic restricted to Gather for the embedding table in int8;
3. convert_float_to_float16 for the remainder, with the int8/QDQ ops and MatMulNBits blocked.

Results are validated against the fp32 logits of the original PyTorch model: the fp32 export matches to 1.5e-05, and the quantized variants are checked for score drift and for verdict flips on passages that sit near the 0.5 decision boundary.

P(AI) is not a calibrated authorship probability, and the upstream card warns against sole reliance on it for high-stakes decisions. MIT, inherited from the original model.