---
tags:
  - mic
  - test-artifact
base_model: answerdotai/ModernBERT-base
---

# Slim fixture: mic-modernbert-slim

A 3.4M-parameter fixture for the [modernbert MIC](https://huggingface.co/hf-internal-testing/modernbert-integration), covering [`answerdotai/ModernBERT-base`](https://huggingface.co/answerdotai/ModernBERT-base). It is a test artifact, not a usable model, tagged `test-artifact` to keep it out of candidate-model search.

- **Fixture key `d109ab451c9f`.** It covers every checkpoint whose processor files are byte-identical and whose config matches after shrinking.
- **Same architecture, smaller config:** `ModernBertForMaskedLM`, shrunk by the generic rule in [`sweep.py`](https://github.com/huggingface/model-integration-contracts/blob/main/experiments/sweep.py) (num_hidden_layers 2).
- **Processor files copied byte for byte** from `answerdotai/ModernBERT-base`: `special_tokens_map.json`, `tokenizer.json`, `tokenizer_config.json`.
- **Random weights (seed 17).** They passed the input-sensitivity gate: every perturbation of the contract's inputs moved the logits by at least 0.001 (weakest: `attention_mask:all_ones`, 0.00121), so no training was needed.
- **Same tensor names as the real checkpoint.** The real checkpoint has every parameter, and so does the fixture.
- **Saved in float32**, the dtype `answerdotai/ModernBERT-base` loads in by default.
- **Finite in float32, bfloat16, and float16** (forward, loss, gradients).

Built by [`build_fixtures.py`](https://github.com/huggingface/model-integration-contracts/blob/main/example/build_fixtures.py); [`build.json`](build.json) records the pinned sources, gate results, and file hashes. The source repository commits only `README.md` and `build.json`; rebuild the other files with `python example/build_fixtures.py --fixture mic-modernbert-slim`.