diff --git a/README.md b/README.md
index 20ab2c9b..1060f3d3 100644
--- a/README.md
+++ b/README.md
@@ -8,7 +8,6 @@
 [![CodeQL](https://github.com/microsoft/RD-Agent/actions/workflows/github-code-scanning/codeql/badge.svg)](https://github.com/microsoft/RD-Agent/actions/workflows/github-code-scanning/codeql)
 [![Dependabot Updates](https://github.com/microsoft/RD-Agent/actions/workflows/dependabot/dependabot-updates/badge.svg)](https://github.com/microsoft/RD-Agent/actions/workflows/dependabot/dependabot-updates)
 [![Lint PR Title](https://github.com/microsoft/RD-Agent/actions/workflows/pr.yml/badge.svg)](https://github.com/microsoft/RD-Agent/actions/workflows/pr.yml)
-[![Readthedocs Preview](https://github.com/microsoft/RD-Agent/actions/workflows/readthedocs-preview.yml/badge.svg)](https://github.com/microsoft/RD-Agent/actions/workflows/readthedocs-preview.yml)
 [![Release.yml](https://github.com/microsoft/RD-Agent/actions/workflows/release.yml/badge.svg)](https://github.com/microsoft/RD-Agent/actions/workflows/release.yml)
 [![Platform](https://img.shields.io/badge/platform-Linux-blue)](https://pypi.org/project/rdagent/#files)
 [![PyPI](https://img.shields.io/pypi/v/rdagent)](https://pypi.org/project/rdagent/)
@@ -18,6 +17,7 @@
 [![pre-commit](https://img.shields.io/badge/pre--commit-enabled-brightgreen?logo=pre-commit)](https://github.com/pre-commit/pre-commit)
 [![Checked with mypy](https://www.mypy-lang.org/static/mypy_badge.svg)](http://mypy-lang.org/)
 [![Ruff](https://img.shields.io/endpoint?url=https://raw.githubusercontent.com/astral-sh/ruff/main/assets/badge/v2.json)](https://github.com/astral-sh/ruff)
+[![Readthedocs Preview](https://github.com/microsoft/RD-Agent/actions/workflows/readthedocs-preview.yml/badge.svg)](https://github.com/microsoft/RD-Agent/actions/workflows/readthedocs-preview.yml) <!-- this badge is too long, please place it in the last one to make it pretty --> 
 
 # 📰 News
 | 🗞️ News        | 📝 Description                 |
diff --git a/rdagent/core/conf.py b/rdagent/core/conf.py
index 8cb2e055..202ac1ea 100644
--- a/rdagent/core/conf.py
+++ b/rdagent/core/conf.py
@@ -38,7 +38,7 @@ class RDAgentSettings(BaseSettings):
     chat_openai_api_key: str = ""
     chat_azure_api_base: str = ""
     chat_azure_api_version: str = ""
-    chat_model: str = ""
+    chat_model: str = "gpt-4-turbo"
     chat_max_tokens: int = 3000
     chat_temperature: float = 0.5
     chat_stream: bool = True