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Stream Session Thread Events

get/v1/sessions/{session_id}/threads/{thread_id}/stream?beta=true

Path parameters

session_idstring required

Path parameter session_id

thread_idstring required

Path parameter thread_id

Query parameters

event_deltas[]BetaManagedAgentsEventDeltaType[]

When set, this connection also receives streaming deltas (event_start, event_delta) while an event is being produced, before the event itself arrives. Deltas are best-effort; when the final event is produced it carries the complete content. A model request that ends early (an error or interrupt) produces no final event — its terminal span.model_request_end closes the preview. Accepts one or more event types to preview and may be repeated: agent.message streams content_delta fragments; agent.thinking is start-only — a signal that the agent has begun extended thinking, concluded by the agent.thinking event itself. Only previews of the requested event types are sent.

Headers

x-api-keystring
anthropic-versionstring
anthropic-betastring

Response

Successful response (OK)

OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR
OR

Example response

{
  "type": "user.message",
  "id": "sevt_011CZkZGOp0iBcp4kaQSihUmy",
  "content": [
    {
      "type": "text",
      "text": "Where is my order #1234?"
    }
  ],
  "processed_at": "2026-03-15T10:00:00Z"
}

Changes

Changed in 16 of the 68 revisions of this API.7367

  • d1d189d791d12See the full diff
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      added subschema #2 to the ////////// response property anyOf list for the response status

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      added subschema #2 to the ///////////////////////// response property anyOf list for the response status

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    This revision also has 1 change that name no endpoint, such as unreferenced schemas being removed. See the revision's changelog

  • 0042750ea1ee82See the full diff
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      added to the /////////////////////////////// response property oneOf list for the response status

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      removed the required property ///////////////// from the response with the status

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      added discriminator to /////////////////////////////// response property for the response status

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      added discriminator to //////////////// response property for the response status

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      response property oneOf[BetaManagedAgentsAgentCustomToolUseEvent]/session_thread_id list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsAgentMcpToolResultEvent]/content/items/oneOf[BetaManagedAgentsDocumentBlock]/context list-of-types was widened by adding types null to media type application/json of response 200

      response-property-list-of-types-widened

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      response property oneOf[BetaManagedAgentsAgentMcpToolResultEvent]/content/items/oneOf[BetaManagedAgentsDocumentBlock]/title list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsAgentMcpToolResultEvent]/is_error list-of-types was widened by adding types null to media type application/json of response 200

      response-property-list-of-types-widened

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      response property oneOf[BetaManagedAgentsAgentMcpToolUseEvent]/session_thread_id list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsAgentThreadMessageReceivedEvent]/content/items/oneOf[BetaManagedAgentsDocumentBlock]/context list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsAgentThreadMessageReceivedEvent]/content/items/oneOf[BetaManagedAgentsDocumentBlock]/title list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsAgentThreadMessageReceivedEvent]/from_agent_name list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsAgentThreadMessageSentEvent]/content/items/oneOf[BetaManagedAgentsDocumentBlock]/context list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsAgentThreadMessageSentEvent]/content/items/oneOf[BetaManagedAgentsDocumentBlock]/title list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsAgentThreadMessageSentEvent]/to_agent_name list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsAgentToolResultEvent]/content/items/oneOf[BetaManagedAgentsDocumentBlock]/context list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsAgentToolResultEvent]/content/items/oneOf[BetaManagedAgentsDocumentBlock]/title list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsAgentToolResultEvent]/is_error list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsAgentToolUseEvent]/session_thread_id list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsSessionUpdatedEvent]/title list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsSpanModelRequestEndEvent]/is_error list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsUserCustomToolResultEvent]/content/items/oneOf[BetaManagedAgentsDocumentBlock]/context list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsUserCustomToolResultEvent]/content/items/oneOf[BetaManagedAgentsDocumentBlock]/title list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsUserCustomToolResultEvent]/is_error list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsUserCustomToolResultEvent]/session_thread_id list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsUserDefineOutcomeEvent]/max_iterations list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsUserInterruptEvent]/session_thread_id list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsUserMessageEvent]/content/items/oneOf[BetaManagedAgentsDocumentBlock]/context list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsUserMessageEvent]/content/items/oneOf[BetaManagedAgentsDocumentBlock]/title list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsUserToolConfirmationEvent]/deny_message list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsUserToolConfirmationEvent]/session_thread_id list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsUserToolResultEvent]/content/items/oneOf[BetaManagedAgentsDocumentBlock]/context list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsUserToolResultEvent]/content/items/oneOf[BetaManagedAgentsDocumentBlock]/title list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsUserToolResultEvent]/is_error list-of-types was widened by adding types null to media type application/json of response 200

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      response property oneOf[BetaManagedAgentsUserToolResultEvent]/session_thread_id list-of-types was widened by adding types null to media type application/json of response 200

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      the //// response property's maxLength was unset from 10000 for the response status

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      removed from the //// response property allOf list for the response status

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      added subschema #2 to the //// response property anyOf list for the response status

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      added subschema #2 to the //// response property anyOf list for the response status

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      added subschema #2 to the //// response property anyOf list for the response status

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      added subschema #2 to the ///////// response property anyOf list for the response status

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      added subschema #2 to the ///////// response property anyOf list for the response status

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      added subschema #2 to the //// response property anyOf list for the response status

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      added subschema #2 to the //// response property anyOf list for the response status

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      added subschema #2 to the //// response property anyOf list for the response status

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      added subschema #2 to the //// response property anyOf list for the response status

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      added subschema #2 to the //// response property anyOf list for the response status

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      added subschema #2 to the //// response property anyOf list for the response status

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  • 93d8fd7d64932110See the full diff
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      added to the response body oneOf list for the response status

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      the /////////////////// response's property type changed from object to no type for status

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      removed the required property ////// from the response with the status

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      removed the required property //////////////////// from the response with the status

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      added session.usage mapping keys to the response discriminator for the response status

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      added the optional property ////////// to the response with the status

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      added the optional property //// to the response with the status

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      added discriminator to ///// response property for the response status

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      added discriminator to /////////////////// response property for the response status

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      added budget_reached discriminator mapping keys to the //// response property for the response status

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      added budget_reached discriminator mapping keys to the //// response property for the response status

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      added redacted discriminator mapping keys to the ///// response property for the response status

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      added redacted discriminator mapping keys to the ///// response property for the response status

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      added redacted discriminator mapping keys to the ///// response property for the response status

      response-property-discriminator-mapping-added

    This revision also has 1 change that name no endpoint, such as unreferenced schemas being removed. See the revision's changelog

  • a97790bd7f184See the full diff
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      added subschema #4 subschema #5 subschema #6 subschema #7 subschema #11 subschema #12 to the ////////// response property anyOf list for the response status

      response-property-any-of-added

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      added subschema #4 subschema #5 subschema #6 subschema #7 subschema #11 subschema #12 to the ///////////////////// response property anyOf list for the response status

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      removed subschema #4 subschema #5 subschema #6 subschema #10 subschema #11 from the ////////// response property anyOf list for the response status

      response-property-any-of-removed

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      removed subschema #4 subschema #5 subschema #6 subschema #10 subschema #11 from the ///////////////////// response property anyOf list for the response status

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  • 5e4a8830793b3See the full diff
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      added the new optional query request parameter event_deltas[]

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      added the optional property ////////// to the response with the status

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    • ○

      added the optional property ///////////////////// to the response with the status

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    This revision also has 7 changes that name no endpoint, such as unreferenced schemas being removed. See the revision's changelog

  • 26335fd8487a11See the full diff
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      added to the response body oneOf list for the response status

      response-body-one-of-added

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      added event_start event_delta mapping keys to the response discriminator for the response status

      response-body-discriminator-mapping-added

    This revision also has 20 changes that name no endpoint, such as unreferenced schemas being removed. See the revision's changelog

  • 7caa9a75ddbc2See the full diff
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      added subschema #2 to the ////////// response property anyOf list for the response status

      response-property-any-of-added

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      added subschema #2 to the ///////////////////// response property anyOf list for the response status

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  • 2336fecb081b22See the full diff
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      added to the response body oneOf list for the response status

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      added to the //// response property oneOf list for the response status

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      added system.message mapping keys to the response discriminator for the response status

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      added credential_host_unreachable_error discriminator mapping keys to the //// response property for the response status

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  • 00259327305f2See the full diff
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      added subschema #2 to the ////////// response property anyOf list for the response status

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      added subschema #2 to the ///////////////////// response property anyOf list for the response status

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