Add model card for Parcae-medium-370m

This PR adds a model card for the `parcae-medium-370m` model. The model card includes:
- Metadata for the `text-generation` pipeline.
- Links to the [paper](https://arxiv.org/abs/2604.12946), [GitHub repository](https://github.com/sandyresearch/parcae), and [project page](https://sandyresearch.github.io/parcae/).
- A brief overview of the Parcae architecture.
- Instructions for installation and sample usage code.
- Model architecture specifications and citation information.

README.md

@@ -0,0 +1,52 @@
+---
+pipeline_tag: text-generation
+---
+
+# Parcae-medium-370m
+
+Parcae is a novel stable, looped language model architecture introduced in the paper [Parcae: Scaling Laws For Stable Looped Language Models](https://arxiv.org/abs/2604.12946).
+
+Looped architectures scale compute by passing activations through a block of layers multiple times. Parcae addresses common instability issues in looped models (such as residual explosion and loss spikes) by recasting looping as a nonlinear time-variant dynamical system and constraining the spectral norm of injection parameters.
+
+- **Paper:** [https://arxiv.org/abs/2604.12946](https://arxiv.org/abs/2604.12946)
+- **Repository:** [https://github.com/sandyresearch/parcae](https://github.com/sandyresearch/parcae)
+- **Project Page:** [https://sandyresearch.github.io/parcae/](https://sandyresearch.github.io/parcae/)
+
+## Installation
+
+To use this model, you can install the `parcae-lm` package:
+
+```bash
+pip install parcae-lm
+```
+
+## Usage
+
+You can instantiate the model and load the pretrained weights using the following code:
+
+```python
+import parcae_lm
+
+# Load the pretrained model from HuggingFace
+model = parcae_lm.from_pretrained("SandyResearch/parcae-medium-370m")
+```
+
+## Model Dimensions
+
+| Model | Parameters | Prelude | Core | Coda | Model dim. | Recurrence |
+|-------|-----------|---------|------|------|-----------|------------|
+| Parcae-medium-370M | 370M | 4 | 4 | 4 | 1024 | 8 |
+
+## Citation
+
+```bibtex
+@misc{prairie2026parcaescalinglawsstable,
+      title={Parcae: Scaling Laws For Stable Looped Language Models}, 
+      author={Hayden Prairie and Zachary Novack and Taylor Berg-Kirkpatrick and Daniel Y. Fu},
+      year={2026},
+      eprint={2604.12946},
+      archivePrefix={arXiv},
+      primaryClass={cs.LG},
+      url={https://arxiv.org/abs/2604.12946}, 
+}
+```