---
license: apache-2.0

license_link: https://huggingface.co/Qwen/Qwen2.5-0.5B/blob/main/LICENSE
language:

    - en

pipeline_tag: text-generation

library_name: transformers
---

---
license: apache-2.0

base_model: Qwen/Qwen2.5-0.5B

tags:

    - qwen
    - schema-aware
    - structured-output
    - preweb
---
# Qwen2.5-0.5B-Preweb-Base

This model is a **derivative base model** of `Qwen/Qwen2.5-0.5B`.

It extends the tokenizer vocabulary with schema/control special tokens

---
## 🔧 What’s Changed

Added the following special tokens to the tokenizer:

    - `<|domain_start|>`, `<|domain_end|>`
    - `<|intent_start|>`, `<|intent_end|>`
    - `<|slot_type_start|>`, `<|slot_type_end|>`
    - `<|slot_span_start|>`, `<|slot_span_end|>`
    - `<|canonical_start|>`, `<|canonical_end|>`

As a result:
    - Tokenizer vocabulary size is increased.
---

## 🎯 Intended Usage

This model is intended to be used as a **base model** for:

    - schema-aware prompting
    - structured information extraction
    - slot / intent / domain prediction

All downstream **LoRA adapters must be trained with the same tokenizer**.

---
## 🚫 Compatibility Notes
    - Vocabulary shapes are **fixed**
    - Do NOT add or remove tokens at runtime
    - Designed for **vLLM / TensorRT-LLM** serving
    - Safe for multi-LoRA dynamic loading
---

## 📜 License

Apache-2.0
This model is a derivative work of `Qwen/Qwen2.5-0.5B`.