MLX local inference
This is the 4-bit MLX version of NeoHorse-1-4B for Apple Silicon. Converted from the original BF16 weights with MLX-LM, using affine quantization (group size 64). Benchmark scores below refer to the original model, not a separate evaluation of this quantized version.
The model downloads automatically from Hugging Face. The original chat template is preserved. See Deployment for local checkpoints, the chat API, and tool calling.
NeoHorse-1-4B
Towards Recursive Self-Improvement via Agentic Post-Training with Routing Harness.
Technical Report
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NeoHorse-1-4B is a 4B causal language model and an initial prototype on the path toward recursive self-improvement (RSI). It is post-trained from Qwen3.5-4B for text-based agent harnesses, tool use, coding, and instruction following.
Derived from Qwen/Qwen3.5-4B and fine-tuned by TokenRhythm. The source checkpoint was repackaged for text-only inference. This repository contains language-model weights only, converted for the MLX runtime with 4-bit affine weight quantization (group size 64).
Highlights
- Path toward RSI: the routing harness assigns tasks to a heterogeneous model pool, records tool interactions and outcomes, estimates capability demand, and uses capability-level feedback to shape the next training mixture. Updated models can return to the harness, closing a prototype evaluation–selection–update loop; extending this loop across successive iterations is the next step toward RSI.
- Agentic post-training framework: the associated research explores routing-guided curriculum SFT and routing-guided on-policy distillation to turn execution trajectories into training signal while preserving execution and harness context around each response.
- Data quality: exact and near-duplicate removal, evaluation decontamination, structural validation, six-dimensional semantic evaluation, and subscene-level Scene/Goal/Outcome labeling.
- Broad gains: 64.87 macro average across ten benchmarks versus 58.94 for Qwen3.5-4B (+5.93).
Model Details
Evaluation
The 4B track compares NeoHorse-1-4B with five representative open-weight models. Results are grouped by capability in the table below. Higher is better; Δ is NeoHorse-1-4B minus Qwen3.5-4B. Bold marks the best available result; underlining marks the second-best.
* Nanbeige-4.2-3B LiveCodeBench v6 result is reported in the corresponding model's official blog post or technical report.
Reported protocol: SGLang v0.5.17 · temperature=1.0 · top_p=0.95 · top_k=20 · min_p=0.0 · presence_penalty=1.5 · repetition_penalty=1.0 · thinking mode enabled with enable_thinking=true and force_nonempty_content=true. QwenClawBench, WorkBuddy Bench, and tau2-Bench use three runs; PinchBench and VitaBench use one run; the remaining benchmarks follow their official protocols. VitaBench uses the DeepSeek-V4-Flash simulator and judge.
Deployment
Use MLX-LM on an Apple Silicon Mac to run this checkpoint.
Install and select a local checkpoint
Set MODEL_PATH to the downloaded MLX directory containing config.json, tokenizer files, chat_template.jinja, and model weights. You can also use TokenRhythm/NeoHorse-1-4B-MLX-4bit as the model path to download it automatically from Hugging Face.
Chat locally
Start an API server
The server exposes an OpenAI-compatible /v1/chat/completions endpoint. In the requests below, default_model refers to the checkpoint selected with --model.
Basic Usage
After the server starts, run this request in another terminal:
The generated reply is returned in choices[0].message.content.
Tool Calling
Pass function definitions in the tools field:
MLX-LM reads the preserved chat template to format tool requests and parse generated calls. When the model chooses to call a tool, the call is returned in choices[0].message.tool_calls. Your application executes the function, appends the assistant message and a role: "tool" result with the matching tool_call_id, then sends the conversation back to the same endpoint for the final answer.
License
NeoHorse-1-4B is released under the Apache License 2.0.
The upstream model is Qwen/Qwen3.5-4B. Its original copyright notice, Copyright 2026 Alibaba Cloud, is retained in the license file. TokenRhythm fine-tuned and repackaged the source checkpoint for text-only inference. This repository provides its MLX conversion with 4-bit affine weight quantization (group size 64).
Citation
For questions or issue reports, use the NeoHorse project repository.