Qwen-2.5-7B-ConsistentChat

1. Introduction

Qwen-2.5-7B-ConsistentChat is a 7B instruction-tuned chat model focused on multi-turn consistency. It is fine-tuned from the Qwen/Qwen2.5-7B base model on the ConsistentChat dataset, which is built with a skeleton-guided pipeline that explicitly models human conversational intent to reduce topic drift and improve goal completion in long dialogues. The dataset contains ~15K multi-turn conversations and ~224K utterances.

Compared with generic SFT data, ConsistentChat emphasizes cross-turn consistency: it first models one of nine conversation intent trajectories, then generates a query “skeleton,” and finally fills responses, leading to substantially better consistency and task success on Light, TopDial, and MT-Eval benchmarks.

This repo contains the instruction-tuned 7B ConsistentChat model, with the following base specs inherited from Qwen2.5-7B:

• Type: Causal Language Model
• Training Stage: Pretraining + Supervised Fine-Tuning (this repo)
• Architecture: Transformers with RoPE, SwiGLU, RMSNorm, and Attention QKV bias
• Parameters: 7.61B (6.53B non-embedding)
• Layers: 28
• Attention Heads (GQA): 28 for Q, 4 for KV
• Context Length: up to 131,072 tokens

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2. What makes “ConsistentChat” different?

• Skeleton-Guided Multi-Turn Synthesis. Conversations are generated by first modeling human intent and information flow, then building a query skeleton, and finally generating responses. This reduces topic drift across turns.
• Nine intent trajectories. The dataset covers nine common interaction patterns (summarizing from real conversational dataset, including problem-solving, educational tutoring), each with curated information flow rules that enforce global coherence.
• Empirically better consistency & success. Fine-tuning with ConsistentChat yields 20–30% consistency gains and up to +15% task-success improvements on multi-turn benchmarks vs. common SFT datasets(ShareGPT, ChatAlpaca, UltraChat, LmsysChat...).

Representative MT-Eval (judge: Qwen-2.5-72B-Instruct) results:

• Qwen-2.5-7B-ConsistentChat: ST avg 8.07, MT avg 8.38
• Outperforms variants trained on ShareGPT / UltraChat / LMSYS-Chat for both single-turn and multi-turn settings.

The improvements in commonsense tasks are more pronounced, with particularly strong gains in reasoning (↑ 30.4%) and coding (↑ 33.7%).

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3. Requirements

We recommend the latest transformers. Using transformers < 4.37.0 will raise:

KeyError: 'qwen2'

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4. Quickstart

Below shows how to load the tokenizer and model and chat via apply_chat_template.

from transformers import AutoModelForCausalLM, AutoTokenizer
import torch

model_name = "jiawei-ucas/Qwen-2.5-7B-ConsistentChat"

model = AutoModelForCausalLM.from_pretrained(
    model_name,
    torch_dtype="auto",
    device_map="auto"
)
tokenizer = AutoTokenizer.from_pretrained(model_name)

prompt = "Plan a weekend trip to Kyoto, and remember I’m vegetarian."
messages = [
    {"role": "user", "content": prompt},
]

text = tokenizer.apply_chat_template(
    messages,
    tokenize=False,
    add_generation_prompt=True
)
model_inputs = tokenizer([text], return_tensors="pt").to(model.device)

generated_ids = model.generate(
    **model_inputs,
    max_new_tokens=512
)
generated_ids = [
    output_ids[len(input_ids):] for input_ids, output_ids in zip(model_inputs.input_ids, generated_ids)
]

response = tokenizer.batch_decode(generated_ids, skip_special_tokens=True)[0]

vLLM

We recommend using vLLM for more efficient inference.

pip install vllm==0.8.5.post1

vllm serve /path/to/Qwen-2.5-7B-ConsistentChat --port 8080 --served-model-name Qwen-2.5-7B-ConsistentChat

API endpoint

By default, the OpenAI-compatible server is exposed at: http://<server-ip>:8080/v1

Use with Open-WebUI (recommended for visual chat)

1. Launch Open-WebUI.
2. Go to Settings → Connections / Providers → Add OpenAI-Compatible.
3. Set Base URL to http://<server-ip>:8080/v1.
4. Set API Key to any non-empty string (e.g., sk-local).

You can also test via cURL:

curl http://<server-ip>:8080/v1/chat/completions \
  -H "Authorization: Bearer sk-local" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "Qwen-2.5-7B-ConsistentChat",
    "messages": [
      {"role": "user", "content": "Say hello in one sentence."}
    ],
    "max_tokens": 128
  }'

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5. Intended Use

• Use cases: Assistants requiring stable behavior across many turns (planning, tutoring, troubleshooting, role-play with consistent persona or constraints).
• Out-of-scope: Safety-critical advice, legal/medical counsel, or contexts where factual guarantees and up-to-date knowledge are required.

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Citation

If you find our work helpful, feel free to give us a cite.

@misc{chen2025consistentchat,
      title={ConsistentChat: Building Skeleton-Guided Consistent Dialogues for Large Language Models from Scratch}, 
      author={Jiawei Chen and Xinyan Guan and Qianhao Yuan and Guozhao Mo and Weixiang Zhou and Yaojie Lu and Hongyu Lin and Ben He and Le Sun and Xianpei Han},
      year={2025},
      eprint={2506.03558},
      archivePrefix={arXiv},
      primaryClass={cs.CL},
      url={https://arxiv.org/abs/2506.03558}, 
}