Code2World

Code2World-8B

Given a current GUI observation and an action, Code2World predicts the next screenshot via renderable code generation.

Quickstart

Below, we provide the main demo script for running one example case to show how to use Code2World with 🤗 Transformers.

To keep the demo clear and reusable, it relies on the following components:

• prompt_builder.py: builds the text prompt from the task instruction and action.
• visual_hint.py: adds visual action hints (e.g. click circles or swipe arrows) to the input screenshot.
• render_utils.py: post-processes generated HTML, renders it into an image, and saves outputs.

The code of Code2World has been in the latest Hugging Face transformers and we advise you to build from source with command:

pip install transformers==4.57.0

import torch
from PIL import Image
from transformers import AutoProcessor, Qwen3VLForConditionalGeneration

from prompt_builder import SYSTEM_PROMPT, build_user_prompt
from visual_hint import build_visual_hint
from render_utils import extract_clean_html, render_html_to_image, save_demo_outputs


# ============================================================
# 1. Load model
# ============================================================

MODEL_NAME = "GD-ML/Code2World"

model = Qwen3VLForConditionalGeneration.from_pretrained(
    MODEL_NAME,
    dtype=torch.bfloat16,
    attn_implementation="flash_attention_2",
    device_map="auto",
)

processor = AutoProcessor.from_pretrained(MODEL_NAME)


# ============================================================
# 2. Helper functions
# ============================================================

def build_messages(image, instruction, action):
    user_prompt = build_user_prompt(
        instruction_str=instruction,
        action=action,
    )

    messages = [
        {
            "role": "system",
            "content": [{"type": "text", "text": SYSTEM_PROMPT}],
        },
        {
            "role": "user",
            "content": [
                {"type": "image", "image": image.convert("RGB")},
                {"type": "text", "text": user_prompt},
            ],
        },
    ]
    return messages


@torch.inference_mode()
def generate_html(image, instruction, action, max_new_tokens=8192):
    messages = build_messages(
        image=image,
        instruction=instruction,
        action=action,
    )

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

    generated_ids = model.generate(
        **inputs,
        max_new_tokens=max_new_tokens,
    )

    generated_ids_trimmed = [
        out_ids[len(in_ids):]
        for in_ids, out_ids in zip(inputs.input_ids, generated_ids)
    ]

    output_text = processor.batch_decode(
        generated_ids_trimmed,
        skip_special_tokens=True,
        clean_up_tokenization_spaces=False,
    )[0]

    html = extract_clean_html(output_text)
    return html


def run_demo(case_data, output_dir="./demo_outputs"):
    """
    case_data：
    - images[0]
    - instruction
    - action
    """
    image_path = case_data["images"][0]
    instruction = case_data["instruction"]
    action = case_data["action"]

    image = Image.open(image_path).convert("RGB")
    hinted_image = build_visual_hint(image, action)

    html = generate_html(
        image=hinted_image,
        instruction=instruction,
        action=action,
    )

    rendered_image = render_html_to_image(html)

    save_demo_outputs(
        output_dir=output_dir,
        hinted_image=hinted_image,
        html=html,
        rendered_image=rendered_image,
    )

    return hinted_image, html, rendered_image


# ============================================================
# 3. Example case
# ============================================================

if __name__ == "__main__":
    case_data = {
        "images": [
            "demo_case.png"
        ],
        "instruction": "Click on the Search Omio button.",
        "action": {
            "action_type": "click",
            "x": 540,
            "y": 1470
        }
    }

    run_demo(case_data, output_dir="./demo_outputs")

Citation

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

@article{zheng2026code2world,
  title={Code2World: A GUI World Model via Renderable Code Generation},
  author={Zheng, Yuhao and Zhong, Li'an and Wang, Yi and Dai, Rui and Liu, Kaikui and Chu, Xiangxiang and Lv, Linyuan and Torr, Philip and Lin, Kevin Qinghong},
  journal={arXiv preprint arXiv:2602.09856},
  year={2026}
}