Step-3.5-Flash-Int4

pip install --upgrade "openai>=1.0"

# via Docker
docker pull vllm/vllm-openai:nightly

# or via pip (nightly wheels)
pip install -U vllm --pre \
  --index-url https://pypi.org/simple \
  --extra-index-url https://wheels.vllm.ai/nightly

### 6.2 SGLang

1. Install SGLang.

2. Launch the server.
  - For bf16 model

## 7. Using Step 3.5 Flash on Agent Platforms

### 7.1 Claude Code & Codex
It's straightforward to add Step 3.5 Flash to the list of models in most coding environments. See below for the instructions for configuring Claude Code and Codex to use Step 3.5 Flash.

#### 7.1.1 Prerequisites
Sign up at StepFun.ai or OpenRouter and grab an API key, as mentioned in the Quick Start.

#### 7.1.2 Environment setup
Claude Code and Codex rely on Node.js. We recommend installing Node.js version > v20. You can install Node via nvm.

**Mac/Linux**:

**Windows**:
You can download the installation file (`nvm-setup.exe`) from [https://github.com/coreybutler/nvm-windows/releases](https://github.com/coreybutler/nvm-windows/releases). Follow the instructions to install nvm. Run nvm commands to make sure it is installed.

#### 7.1.3 Use Step 3.5 Flash on Claude Code

1. Install Claude Code.

2. Configure Claude Code.

  To accommodate diverse workflows in Claude Code, we support both **Anthropic-style** and **OpenAI-style** APIs. 

  **Option A: Anthropic API style**:

  > If you intend to use the **OpenRouter** API, refer to the OpenRouter integration guide.  

  Step 1: Edit Claude Settings. Update `~/.claude/settings.json`.
  > You only need to modify the fields shown below. Leave the rest of the file unchanged.

**Option B: OpenAI API style**

  > Note: OpenAI API style here refers to the `chat/completions/` format.

  > We recommend using `claude-code-router`. For details, see [https://github.com/musistudio/claude-code-router](https://github.com/musistudio/claude-code-router).

  After Claude Code is installed, install `claude-code-router` :

Add the following configurations to `~/.claude-code-router/config.json`.

#### 7.1.4 Use Step 3.5 Flash on Codex
1. Install Codex

2. Configure Codex
Add the following settings to `~/.codex/config.toml`, keeping the rest of the settings as they are.