📄 ai-sdk/docs/reference/ai-sdk-core/default-settings-middleware

defaultSettingsMiddleware is a middleware function that applies default settings to language model calls. This is useful when you want to establish consistent default parameters across multiple model invocations.

import { defaultSettingsMiddleware } from 'ai';
const middleware = defaultSettingsMiddleware({  settings: {    temperature: 0.7,    maxOutputTokens: 1000,    // other settings...  },});

Import

import { defaultSettingsMiddleware } from "ai"

API Signature

Parameters

The middleware accepts a configuration object with the following properties:

settings: An object containing default parameter values to apply to language model calls. These can include any valid LanguageModelV2CallOptions properties and optional provider metadata.

Returns

Returns a middleware object that:

Merges the default settings with the parameters provided in each model call
Ensures that explicitly provided parameters take precedence over defaults
Merges provider metadata objects

Usage Example

import { streamText } from 'ai';import { wrapLanguageModel } from 'ai';import { defaultSettingsMiddleware } from 'ai';import { openai } from 'ai';
// Create a model with default settingsconst modelWithDefaults = wrapLanguageModel({  model: openai.ChatTextGenerator({ model: 'gpt-4' }),  middleware: defaultSettingsMiddleware({    settings: {      temperature: 0.5,      maxOutputTokens: 800,      providerMetadata: {        openai: {          tags: ['production'],        },      },    },  }),});
// Use the model - default settings will be appliedconst result = await streamText({  model: modelWithDefaults,  prompt: 'Your prompt here',  // These parameters will override the defaults  temperature: 0.8,});

How It Works

The middleware: