ExtractReasoningMiddleware

Namespace: Vercel.AI

public sealed class ExtractReasoningMiddleware : LanguageModelMiddleware, ILanguageModelMiddleware

Splits delimited reasoning, such as <think>...</think>, out of text. Maps to extractReasoningMiddleware.

Inheritance: object → LanguageModelMiddleware

Implements: ILanguageModelMiddleware

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Constructors

ExtractReasoningMiddleware(string, string, bool)

public ExtractReasoningMiddleware(string tagName = "think", string separator = "\n", bool startWithReasoning = false)

Creates middleware for the XML tags <tagName> and </tagName>.

Parameters

Name	Type	Description
tagName	string	Tag name without angle brackets.
separator	string	Joins reasoning blocks, and the text around them.
startWithReasoning	bool	Prepends the opening tag when the model omits it.

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ExtractReasoningMiddleware((string Opening, string Closing), string, bool)

public ExtractReasoningMiddleware((string Opening, string Closing) tagName, string separator = "\n", bool startWithReasoning = false)

Creates middleware for literal delimiters, such as Gemma’s thought channel.

Parameters

Name	Type	Description
tagName	(string Opening, string Closing)	Literal opening and closing delimiters.
separator	string	Joins reasoning blocks, and the text around them.
startWithReasoning	bool	Prepends the opening delimiter when the model omits it.

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Methods

WrapGenerateAsync(LanguageModelCallOptions, Func<LanguageModelCallOptions, CancellationToken, Task<LanguageModelGenerateResult>>, CancellationToken)

public override Task<LanguageModelGenerateResult> WrapGenerateAsync(LanguageModelCallOptions options, Func<LanguageModelCallOptions, CancellationToken, Task<LanguageModelGenerateResult>> next, CancellationToken cancellationToken)

Wraps a generate call.

Parameters

Name	Type	Description
options	LanguageModelCallOptions
next	Func<LanguageModelCallOptions, CancellationToken, Task<LanguageModelGenerateResult>>
cancellationToken	CancellationToken

Returns: Task<LanguageModelGenerateResult>

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WrapStreamAsync(LanguageModelCallOptions, Func<LanguageModelCallOptions, CancellationToken, Task<LanguageModelStreamResult>>, CancellationToken)

public override Task<LanguageModelStreamResult> WrapStreamAsync(LanguageModelCallOptions options, Func<LanguageModelCallOptions, CancellationToken, Task<LanguageModelStreamResult>> next, CancellationToken cancellationToken)

Wraps a stream call.

Parameters

Name	Type	Description
options	LanguageModelCallOptions
next	Func<LanguageModelCallOptions, CancellationToken, Task<LanguageModelStreamResult>>
cancellationToken	CancellationToken

Returns: Task<LanguageModelStreamResult>

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