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API ReferenceAI

Send Message

Non-streaming send: persists the user turn, waits for the full Claude reply, persists and returns both. For programmatic/API callers that don’t want to parse SSE. The interactive UI uses POST /threads/{id}/stream instead.

Authentication

AuthorizationBearer

Bearer authentication of the form Bearer <token>, where token is your auth token.

Path parameters

thread_idstringRequiredformat: "uuid"

Request

This endpoint expects an object.
contentstringRequired1-32000 characters
attachment_idslist of stringsOptional

Response

Successful Response
idstringformat: "uuid"
thread_idstringformat: "uuid"
sequenceinteger
rolestring
contentstring
statusstring
created_atdatetime
thinkingstring or nullOptional
modelstring or nullOptional
input_tokensinteger or nullOptional
output_tokensinteger or nullOptional
stop_reasonstring or nullOptional
errorstring or nullOptional
attachmentslist of objectsOptional

Errors

422
Unprocessable Entity Error