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Represents individual Server-Sent Events (SSE) streamed when stream: true. Each event shows incremental progress during response generation.

Event Types

Response Lifecycle Events

response.created

Emitted when response generation begins.

Show properties

event string - Always response.created

status string - Always in_progress

thread_id string - Thread identifier

is_summarized boolean - Whether conversation was summarized

assistant_id string optional - Assistant ID if thread has one

output_mode string optional - Output format mode (text, plain, blocks)

response.completed

Emitted when response generation completes successfully.

Show properties

event string - Always response.completed

status string - Always completed

thread_id string - Thread identifier

response_id string - Unique response identifier

is_summarized boolean - Whether conversation was summarized

response string optional - Complete response text (not present when using blocks mode)

response_blocks array optional - Structured response blocks (present in blocks mode or when tools are used)

assistant_id string optional - Assistant ID if thread has one

reasoning_content string optional - Complete reasoning content if reasoning was enabled

tools object optional - Tool information if requested via include parameter

response.error

Emitted when an error occurs during response generation.

Show properties

event string - Always response.error

status string - Always failed

message string - Error message

Content Generation Events

response.content_delta

Emitted for each chunk of generated text.

Show properties

event string - Always response.content_delta

delta string - Text chunk

response.block

Emitted for each response block (tool calls, tool results) in blocks mode.

Show properties

event string - Always response.block

block object - Block object with type and content

Block types:

  • text - Text content block
  • tool_call - Tool invocation block
  • tool_result - Tool execution result block

Reasoning Events

reasoning.started

Emitted when model enters reasoning phase.

Show properties

event string - Always reasoning.started

reasoning.content

Emitted for each chunk of reasoning content.

Show properties

event string - Always reasoning.content

content string - Reasoning text chunk

reasoning.completed

Emitted when reasoning phase completes.

Show properties

event string - Always reasoning.completed

{
  "event": "response.created",
  "thread_id": "thread_xyz789",
  "status": "in_progress",
  "is_summarized": false,
  "output_mode": "text"
}