Stepfun

AISDK provides first-class support for Stepfun with fully typed model APIs. Model capabilities are enforced at compile time using Rust's type system. This prevents model capability mismatches and guarantees the selected model is valid for the task (e.g. tool calling).

Installation

Enable the Stepfun provider feature:

cargo add aisdk --features stepfun

This installs AISDK with the Stepfun provider enabled. Once you have enabled the Stepfun provider, you can use all aisdk features with it.

Create a Provider Instance

To create a provider instance, call Stepfun::model_name(), where model_name is the Stepfun model you want to use. Model names are exposed as snake-case methods.

use aisdk::providers::Stepfun;

let stepfun = Stepfun::step_1_32k();

This initializes the provider with:

Model: "step-1-32k"
API key from environment (if set with STEPFUN_API_KEY)
Stepfun's default base URL (https://api.stepfun.com/v1)

Basic Text Generation

Example using LanguageModelRequest for text generation.

use aisdk::{
    core::LanguageModelRequest,
    providers::Stepfun,
};

#[tokio::main]
async fn main() -> Result<(), Box<dyn std::error::Error>> {

    let stepfun = Stepfun::step_1_32k();

    let response = LanguageModelRequest::builder()
        .model(stepfun)
        .prompt("Write a short poem about Rust.")
        .build()
        .generate_text()
        .await?;

    println!("Response text: {:?}", response.text());
    Ok(())
}

Provider Settings

You can customize provider configuration using Stepfun::builder()

API Key

let stepfun = Stepfun::<Step132k>::builder()
    .api_key("your-api-key")
    .build()?;

If not specified, AISDK uses the STEPFUN_API_KEY environment variable.

Base URL

Useful when routing through a proxy, gateway, or self-hosted compatible endpoint.

let stepfun = Stepfun::<Step132k>::builder()
    .base_url("https://api.stepfun.com/v1")
    .build()?;

Path (Full URL Override)

Use .path(...) to override the full request URL instead of only the base URL.

let stepfun = Stepfun::<Step132k>::builder()
    .path("https://full-url.example/v1/chat/completions")
    .build()?;

Provider Name

For logging, analytics, and observability.

let stepfun = Stepfun::<Step132k>::builder()
    .provider_name("Stepfun")
    .build()?;

Full Custom Configuration Example

let stepfun = Stepfun::<Step132k>::builder()
    .api_key("your-api-key")
    .base_url("https://api.stepfun.com/v1")
    .path("https://full-url.example/v1/chat/completions")
    .provider_name("Stepfun")
    .build()?;

Dynamic Model Selection

For runtime model selection (e.g., loading models from config files), use DynamicModel:

Using model_name() Method with Default Settings

use aisdk::providers::Stepfun;

// Specify model as a string at runtime
let stepfun = Stepfun::model_name("step-1-32k");

Using Builder Pattern with Custom Settings

use aisdk::{
    core::DynamicModel,
    providers::Stepfun,
};

let stepfun = Stepfun::<DynamicModel>::builder()
	.model_name("step-1-32k")
	.api_key("your-api-key")
	.base_url("https://api.stepfun.com/v1")
	.path("https://full-url.example/v1/chat/completions")
	.provider_name("Stepfun")
	.build()?;

Warning: When using DynamicModel, model capabilities are not validated at compile time. This means there's no guarantee the model supports requested features (e.g., tool calls, structured output). For compile-time safety, use the typed methods like Stepfun::step_1_32k().

Next Steps

Take a deeper look at text generation features Generating Text / Streaming Text
Explore Structured Output for reliable agent data.
Learn how to create Custom Tools.
Learn more about Agents.

Stepfun

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