gustajunq/openFable-4B-general

OpenFable-4B

"The US banned Fable 5 outside America. I'm outside America. So I made my own."

OpenFable-4B is a fine-tune of Qwen3-4B designed to replicate the conversational style, reasoning depth, and structured output quality of Claude Fable 5 — built entirely from scratch by a solo developer in Brazil.

This is not a generic instruction-tuned model. It's a deliberate attempt to bring Fable-style responses to the open-source ecosystem, with a custom-built dataset and a personality baked into the chat template.

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What makes it different

• Style-first fine-tune — trained to match Claude Fable 5's tone: direct, warm, structured, and non-verbose
• Custom dataset — ~300 hand-curated examples across coding, math, agentic planning, and cybersecurity. No public synthetic datasets that leak CoT preambles
• Custom chat template — default system prompt embedded in tokenizer_config.json: "You are OpenFable, created by SynastrIA Networks"
• GGUF quantized — Q4_K_M, ready for local inference via llama.cpp, LM Studio, PocketPal, or Jan

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Benchmarks

MMLU — Zero-shot (no few-shot)

OpenFable-4B was evaluated on MMLU with zero-shot prompting, achieving an overall score of 68.48%.

Strongest in Social Sciences. Weakest in Humanities — expected given the dataset skew toward technical and reasoning tasks.

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GSM8K — Comparison with 4B-class models

OpenFable-4B holds its own against the competitive 4B landscape on grade-school math reasoning:

OpenFable matches top-tier 4B models on math reasoning despite being a style fine-tune, not a reasoning-optimized model. The base Qwen3-4B it's built on scores ~76% — OpenFable closes that gap significantly through LoRA training.

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Model details

Property	Value
Base model	Qwen/Qwen3-4B
Fine-tuning method	LoRA (via Unsloth)
Dataset size	~300 examples
Quantization	Q4_K_M (GGUF)
Context length	32768
Language	English
License	Apache 2.0

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Usage

llama.cpp

./llama-cli \
  -m OpenFable-4B-Q4_K_M.gguf \
  -p "You are OpenFable, created by SynastrIA Networks." \
  --ctx-size 4096 \
  -i

Python (llama-cpp-python)

from llama_cpp import Llama

llm = Llama(
    model_path="OpenFable-4B-Q4_K_M.gguf",
    n_ctx=4096,
    chat_format="chatml",
)

response = llm.create_chat_completion(
    messages=[
        {"role": "system", "content": "You are OpenFable, created by SynastrIA Networks."},
        {"role": "user", "content": "Explain how LoRA fine-tuning works."},
    ]
)

print(response["choices"][0]["message"]["content"])

LM Studio / Jan / PocketPal

Download the .gguf file and load it directly. The system prompt is already embedded in the tokenizer config — no manual setup required.

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Downloads

Format	Link
GGUF (Q4_K_M)	gustajunq/OpenFable-4B-GGUF
Org page	SynastrIA Networks on HuggingFace

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Known limitations

• Humanities performance lags behind other categories (~59.5% MMLU) — reflective of dataset composition
• Style fine-tune, not RLHF-aligned — may occasionally drift on edge-case prompts
• Not optimized for multilingual use — English only

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About

Built by Gustavo at SynastrIA Networks — a one-person AI startup from Brazil.

OpenFable is part of the broader SynastrIA ecosystem, which includes Lucian, an AI agent platform for creators.

Follow the build-in-public journey: @synastriadev · @openfable

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V2 — June 2026