extractReasoningMiddleware()

extractReasoningMiddleware is a middleware function that extracts XML-tagged reasoning sections from generated text and exposes them separately from the main text content. This is particularly useful when you want to separate an AI model's reasoning process from its final output.

import { extractReasoningMiddleware } from 'ai';


const middleware = extractReasoningMiddleware({
  tagName: 'reasoning',
  separator: '\n',
});

Import 

import { extractReasoningMiddleware } from "ai"

API Signature

Parameters

tagName:

string

separator?:

string

startWithReasoning?:

boolean

Returns

Returns a middleware object that:

  • Processes both streaming and non-streaming responses
  • Extracts content between specified XML tags as reasoning
  • Removes the XML tags and reasoning from the main text
  • Adds a reasoning property to the result containing the extracted content
  • Maintains proper separation between text sections using the specified separator

Type Parameters

The middleware works with the LanguageModelV2StreamPart type for streaming responses.