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FluffBuzz includes a bundled StepFun provider plugin with two provider ids:
  • stepfun for the standard endpoint
  • stepfun-plan for the Step Plan endpoint
Standard and Step Plan are separate providers with different endpoints and model ref prefixes (stepfun/... vs stepfun-plan/...). Use a China key with the .com endpoints and a global key with the .ai endpoints.

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Region and endpoint overview

EndpointChina (.com)Global (.ai)
Standardhttps://api.stepfun.com/v1https://api.stepfun.ai/v1
Step Planhttps://api.stepfun.com/step_plan/v1https://api.stepfun.ai/step_plan/v1
Auth env var: STEPFUN_API_KEY

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Built-in catalog

Standard (stepfun):
Model refContextMax outputNotes
stepfun/step-3.5-flash262,14465,536Default standard model
Step Plan (stepfun-plan):
Model refContextMax outputNotes
stepfun-plan/step-3.5-flash262,14465,536Default Step Plan model
stepfun-plan/step-3.5-flash-2603262,14465,536Additional Step Plan model

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Getting started

Choose your provider surface and follow the setup steps.
Best for: general-purpose use via the standard StepFun endpoint.
1

Choose your endpoint region

Auth choiceEndpointRegion
stepfun-standard-api-key-intlhttps://api.stepfun.ai/v1International
stepfun-standard-api-key-cnhttps://api.stepfun.com/v1China
2

Run onboarding

fluffbuzz onboard --auth-choice stepfun-standard-api-key-intl
Or for the China endpoint:
fluffbuzz onboard --auth-choice stepfun-standard-api-key-cn
3

Non-interactive alternative

fluffbuzz onboard --auth-choice stepfun-standard-api-key-intl \
  --stepfun-api-key "$STEPFUN_API_KEY"
4

Verify models are available

fluffbuzz models list --provider stepfun

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Model refs

  • Default model: stepfun/step-3.5-flash

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Advanced configuration

{
  env: { STEPFUN_API_KEY: "your-key" },
  agents: { defaults: { model: { primary: "stepfun/step-3.5-flash" } } },
  models: {
    mode: "merge",
    providers: {
      stepfun: {
        baseUrl: "https://api.stepfun.ai/v1",
        api: "openai-completions",
        apiKey: "${STEPFUN_API_KEY}",
        models: [
          {
            id: "step-3.5-flash",
            name: "Step 3.5 Flash",
            reasoning: true,
            input: ["text"],
            cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
            contextWindow: 262144,
            maxTokens: 65536,
          },
        ],
      },
    },
  },
}

{
  env: { STEPFUN_API_KEY: "your-key" },
  agents: { defaults: { model: { primary: "stepfun-plan/step-3.5-flash" } } },
  models: {
    mode: "merge",
    providers: {
      "stepfun-plan": {
        baseUrl: "https://api.stepfun.ai/step_plan/v1",
        api: "openai-completions",
        apiKey: "${STEPFUN_API_KEY}",
        models: [
          {
            id: "step-3.5-flash",
            name: "Step 3.5 Flash",
            reasoning: true,
            input: ["text"],
            cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
            contextWindow: 262144,
            maxTokens: 65536,
          },
          {
            id: "step-3.5-flash-2603",
            name: "Step 3.5 Flash 2603",
            reasoning: true,
            input: ["text"],
            cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
            contextWindow: 262144,
            maxTokens: 65536,
          },
        ],
      },
    },
  },
}
  • The provider is bundled with FluffBuzz, so there is no separate plugin install step.
  • step-3.5-flash-2603 is currently exposed only on stepfun-plan.
  • A single auth flow writes region-matched profiles for both stepfun and stepfun-plan, so both surfaces can be discovered together.
  • Use fluffbuzz models list and fluffbuzz models set <provider/model> to inspect or switch models.
For the broader provider overview, see Model providers.

Model selection

Overview of all providers, model refs, and failover behavior.

Configuration reference

Full config schema for providers, models, and plugins.

Model selection

How to choose and configure models.

StepFun Platform

StepFun API key management and documentation.