File size: 2,281 Bytes
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license: mit
base_model: microsoft/FastContext-1.0-4B-SFT
pipeline_tag: text-generation
tags:
- core-ai
- coreml
- on-device
- ios
- iphone
- qwen3
language:
- en
---
> [!WARNING]
> ## Deprecated (2026-07-21)
>
> This port is retired. Two independent reasons:
>
> 1. Microsoft removed the upstream model (`microsoft/FastContext-1.0-4B-SFT`) from
> Hugging Face and GitHub on 2026-06-30 without explanation, so the original weights are
> no longer available.
> 2. The shipped `.aimodelc` here was compiled from a `coreai-torch` 0.4.0 conversion and
> fails to load on iOS/macOS 27 beta 2+. Rebuilding it requires the original weights (see 1).
>
> The repo is kept for reference. Every other model in the
> [zoo](https://github.com/john-rocky/coreai-model-zoo) has been recovered.
# FastContext-1.0-4B-SFT — Core AI (on-device, iPhone)
[microsoft/FastContext-1.0-4B-SFT](https://huggingface.co/microsoft/FastContext-1.0-4B-SFT)
converted to Apple **Core AI** for on-device inference, served by the **CoreAIChat** app.
FastContext is a long-context **repository-exploration agent** (Qwen3-4B-Instruct
backbone, supervised-fine-tuned on exploration traces: broad first-turn search,
multi-turn evidence gathering, and precise file:line citation generation).
## Contents
- `gpu/` — AOT-compiled **GPU (MPSGraph)** bundle, 4-bit linear-INT4, **h18p**
(iPhone 17 / iPhone 18 class). ~2.1 GB. Drop-in for CoreAIChat's
`Documents/models/fastcontext_4b_gpu`.
> **Device class:** this is an **AOT h18p** bundle (iPhone 17 / 18 class). On-device
> specialization of a 4B graph is not viable, so the bundle is precompiled for the
> h18p GPU — the same approach Core AI uses for the Gemma-4B bundle.
## Verified on iPhone 17 Pro (iOS 27)
- **Parity** vs HF fp16 (teacher-forced): **23/24 argmax**, perplexity 1.41 — the
single flip is a near-tie quant-noise position.
- **On-device GPU:** ~**334 tok/s** prefill, ~**16.5 tok/s** decode (512-prompt /
1024-gen), load ~8 s cold, ~0.3 GB resident (weights memory-mapped).
## Use
Install **CoreAIChat**, open the model picker, and select **FastContext 4B**.
## License
MIT, inherited from the base model
[microsoft/FastContext-1.0-4B-SFT](https://huggingface.co/microsoft/FastContext-1.0-4B-SFT).
See `LICENSE`.
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