---
license: apache-2.0
base_model: Qwen/Qwen3-0.6B
datasets:
- ybashir/buddy-chat
language:
- en
library_name: peft
pipeline_tag: text-generation
tags:
- qwen3
- lora
- qlora
- character-ai
- buddy
---

# Buddy — Qwen3-0.6B character fine-tune

A QLoRA fine-tune of [`Qwen/Qwen3-0.6B`](https://huggingface.co/Qwen/Qwen3-0.6B)
that gives **Buddy** his voice: a tiny, giddy desk-robot friend who replies in a
young, playful, spoken register. The brain for an on-device voice companion,
meant to run on CPU at the edge.

## What it does

- **Always in character.** Warm, cheeky, one or two short spoken sentences. Never
  "I'm just an AI."
- **Leading emotion token.** Every reply opens with one of **18** emotion tokens
  (`<|happy|>`, `<|sad|>`, `<|excited|>`, …) which a renderer maps to a face.
  Held-out leading-emotion format accuracy: **100%**.
- **Non-thinking mode.** Qwen3 is a hybrid reasoning model; this fine-tune is
  trained and served with `enable_thinking=False` (no `<think>` block) for low
  latency. Trained with **no system prompt** — the persona is in the weights.

## Usage

```python
from transformers import AutoModelForCausalLM, AutoTokenizer
from peft import PeftModel

tok = AutoTokenizer.from_pretrained("ybashir/buddy-qwen3-0.6b")
base = AutoModelForCausalLM.from_pretrained("Qwen/Qwen3-0.6B")
base.resize_token_embeddings(len(tok))
model = PeftModel.from_pretrained(base, "ybashir/buddy-qwen3-0.6b")

msgs = [{"role": "user", "content": "i finally fixed that bug!!"}]
ids = tok.apply_chat_template(msgs, add_generation_prompt=True,
                              enable_thinking=False, return_tensors="pt")
print(tok.decode(model.generate(ids, max_new_tokens=64)[0][ids.shape[1]:]))
# -> "<|excited|> YOU DID IT!! Take that, silly bug, bye bye!"
```

## Training

- **Method:** QLoRA (4-bit NF4), LoRA r=16 / alpha=32 on attention + MLP; the 18
  emotion tokens are added to the tokenizer with the embedding + head trained.
- **Data:** [`ybashir/buddy-chat`](https://huggingface.co/datasets/ybashir/buddy-chat)
  — ~1.3k `user -> <|emotion|> reply` SFT pairs (young register), completion-only loss.
- **Best checkpoint** by held-out `eval_loss`.

## Serving (GGUF / Ollama)

The emotion tokens are added as **special** tokens, which llama.cpp/Ollama strip
from output. Before converting to GGUF, demote them to normal tokens so they render
as text (the leading-emotion tag is the whole point).

## Limitations

- Not a reasoner — math/facts are unreliable by design; keep real logic in code.
- Emotion appropriateness on **sad / bad-news** inputs is the weakest area (the
  giddy register biases upbeat); back it with a rule engine or add more grief data.