ChatBerry-1.2

🍰 ChatBerry-1.2

ChatBerry-1.2 is a fine-tuned version of artindnr/strawberry-1, converted from a reasoning ("thinking") model into a direct-answer chat model. Reasoning traces are disabled — ChatBerry-1.2 responds directly, without emitting a separate chain-of-thought / analysis channel. This release scales up training data ~6x over ChatBerry-1, resulting in the strongest response quality and consistency in the ChatBerry line so far.

What's New in 1.2

• Trained on ~6x more data than ChatBerry-1
• Best response quality and instruction-following in the ChatBerry family to date, improving further on ChatBerry-1.1
• Same direct-chat behavior: no visible reasoning/analysis channel

<!-- TODO: add specific benchmark numbers or qualitative comparisons vs ChatBerry-1 and ChatBerry-1.1 -->

Model Details

• Base model: artindnr/strawberry-1 (itself fine-tuned from openai/gpt-oss-20b, 21B parameters)
• Architecture: gpt_oss
• Fine-tuned by: artindnr
• License: Apache 2.0
• Languages: Farsi (Persian), English, and multilingual support
• Model type: Causal decoder-only chat language model (reasoning disabled)

Training

ChatBerry-1.2 was fine-tuned from artindnr/strawberry-1 on a further expanded version of the direct chat-style (non-reasoning) SFT data used for ChatBerry-1 — roughly 6x the number of training examples. As with earlier ChatBerry releases, this SFT pass overrides Strawberry-1's reasoning behavior, teaching the model to skip the analysis channel and go straight to a final answer.

<!-- TODO: add exact dataset name/link, training hardware, number of epochs, learning rate, effective batch size, LoRA vs full fine-tune details -->

How to Use

ChatBerry-1.2 uses the gpt-oss chat template (Harmony format) shipped with the base model, so it works with 🤗 Transformers.

Installation

pip install torch --index-url https://download.pytorch.org/whl/cu128
pip install "trl>=0.20.0" "peft>=0.17.0" "transformers>=4.55.0" "kernels>=0.12.0"

This has been verified to work with:

Generation

import torch
from transformers import AutoModelForCausalLM, AutoTokenizer

MODEL_ID = "artindnr/chatberry-1.2"

tokenizer = AutoTokenizer.from_pretrained(MODEL_ID)
model = AutoModelForCausalLM.from_pretrained(
    MODEL_ID,
    torch_dtype=torch.bfloat16,
    device_map="auto",
)

USER_PROMPT = "تو کی هستی و اسمت چیه؟"

messages = [
    {"role": "user", "content": USER_PROMPT},
]

inputs = tokenizer.apply_chat_template(
    messages,
    add_generation_prompt=True,
    tokenize=True,
    return_dict=True,
    return_tensors="pt",
).to(model.device)

outputs = model.generate(
    **inputs,
    max_new_tokens=512,
    temperature=0.6,
    do_sample=True,
)

print(tokenizer.decode(outputs[0][inputs["input_ids"].shape[-1]:], skip_special_tokens=True))

As with earlier ChatBerry releases, there's no need to set a reasoning language system message or parse out separate analysis / final channels — ChatBerry-1.2 goes straight to its final answer, so decoding just the newly generated tokens with skip_special_tokens=True gives you the plain-text response directly.

Intended Use

ChatBerry-1.2 is intended for:

• General-purpose Farsi and multilingual chat assistants
• Applications where direct, low-latency responses are preferred over visible reasoning traces
• Use cases that want the highest-quality ChatBerry checkpoint released so far

Limitations

• ChatBerry-1.2 trades away Strawberry-1's explicit chain-of-thought reasoning; for tasks that benefit from visible step-by-step reasoning, artindnr/strawberry-1 may be a better fit.
• As with any fine-tune, ChatBerry-1.2 inherits the general capabilities and limitations of the gpt-oss-20b base model and the strawberry-1 checkpoint it was built from, including the possibility of hallucinated facts.
• No formal safety fine-tuning beyond what is inherited from the base model and Strawberry-1 has been applied; use appropriate safeguards in production settings.

License

This model is released under the Apache 2.0 license, consistent with the base gpt-oss-20b model and strawberry-1.

Citation

If you use ChatBerry-1.2 in your work, please cite:

@misc{chatberry12,
  title  = {ChatBerry-1.2: A Direct-Answer Chat Fine-tune of Strawberry-1},
  author = {artindnr},
  year   = {2026},
  url    = {https://huggingface.co/artindnr/chatberry-1.2}
}

Acknowledgements

Built on top of artindnr/strawberry-1, itself fine-tuned from openai/gpt-oss-20b.