Fork session

POST/live/sessions/{session_id}/fork

Fork a stored Live session onto a new WebRTC connection.

Path ParametersExpand Collapse

session_id: string

Body ParametersJSONExpand Collapse

transport: object { sdp, type }

WebRTC transport with an SDP offer for the new connection to the forked session.

sdp: string

Session Description Protocol message for the WebRTC connection.

minLength1

type: "webrtc"

The transport used for the Live session. Always webrtc.

session: optional MediaSessionForkConfig { client, delegation, store }

Optional configuration overrides for the new Live session. Omit this object or send an empty object to inherit the stored session’s settings.

client: optional ClientConfig { data_channel }

Startup-only capabilities for an untrusted frontend attached to a unified WebRTC session. Trusted sideband connections are unaffected.

data_channel: DataChannelConfig { allowed_client_events, allowed_server_events }

Client and server event permissions for the WebRTC frontend data channel.

allowed_client_events: optional "all" or array of string

Client event types that the frontend data channel may send. Use ‘all’ to allow every client event; an empty array allows none. Omission preserves the existing allow-all behavior.

One of the following:

"all"

array of string

allowed_server_events: optional "all" or array of ServerEventSelector { type, response_event }

Server events that may be sent to the frontend data channel. Use ‘all’ to allow every server event; an empty array allows none. Omission preserves the existing allow-all behavior. Responses events use an object with type ‘response.event’ and a response_event selector.

One of the following:

"all"

array of ServerEventSelector { type, response_event }

type: string

The outer Live server event type. Use ‘response.event’ for Responses events.

minLength1

maxLength256

response_event: optional string

The nested Responses event type. Required when type is ‘response.event’; forbidden for other event types.

minLength1

maxLength256

delegation: optional object { type, responses }

Update the Responses backend for an existing Live session without changing delegation ownership.

type: "responses"

The delegation owner. Always responses for tasks handled by the Responses API.

responses: optional ResponsesDelegationUpdateConfig { instructions, max_output_tokens, model, 6 more }

Responses backend settings to update. Omitted settings keep their existing values.

instructions: optional string or null

Instructions for the delegated Responses model, separate from Live instructions. See backend prompting.

max_output_tokens: optional number or null

Maximum number of output tokens for each delegated response.

minimum16

model: optional string

The Responses backend model to use for subsequent delegated requests. Omit to keep the current backend model.

parallel_tool_calls: optional boolean or null

Whether the delegated Responses model may request multiple tool calls in a single response.

reasoning: optional object { effort, summary } or null

Reasoning settings passed to each delegated Responses request.

effort: optional "none" or "minimal" or "low" or 3 more or null

How much reasoning effort the delegated Responses model should use. Supported values depend on the backend model.

One of the following:

"none"

"minimal"

"low"

"medium"

"high"

"xhigh"

summary: optional "concise" or "detailed" or "auto" or null

The reasoning summary to request from the delegated Responses model, when supported.

One of the following:

"concise"

"detailed"

"auto"

service_tier: optional "auto" or "default" or "fast_tier_temp_pilot" or 3 more or null

Service tier for delegated Responses requests.

One of the following:

"auto"

"default"

"fast_tier_temp_pilot"

"flex"

"priority"

"ultrafast"

text: optional object { verbosity } or null

Text generation settings passed to each delegated Responses request.

verbosity: optional "low" or "medium" or "high" or null

The amount of detail in text generated by the Responses backend. This does not configure the Live model’s spoken delivery.

One of the following:

"low"

"medium"

"high"

tool_choice: optional "auto" or "none" or "required" or object { name, type } or object { name, server_label, type }

Controls which tool the Responses backend uses when handling a task delegated by the Live model.

One of the following:

LiveToolChoiceEnum = "auto" or "none" or "required"

One of the following:

"auto"

"none"

"required"

LiveFunctionToolChoiceParam object { name, type }

minLength1

maxLength64

type: "function"

LiveMCPToolChoiceParam object { name, server_label, type }

minLength1

maxLength64

server_label: string

minLength1

maxLength64

type: "mcp"

tools: optional array of FunctionTool { name, type, description, 2 more } or object { type }

Tools available to the Responses backend while it handles tasks delegated by the Live model.

One of the following:

FunctionTool object { name, type, description, 2 more }

A function tool available to the Responses backend when the Live model delegates a task.

The name the delegated Responses model uses when calling this function.

type: "function"

The tool type. Always function.

description: optional string or null

What the function does and when the delegated Responses model should call it.

parameters: optional map[unknown] or null

A JSON Schema object describing the arguments accepted by the function.

strict: optional boolean or null

Whether the delegated Responses model must follow the function’s parameter schema exactly.

WebSearch object { type }

A web search tool available to the Live session’s Responses backend.

type: "web_search"

The tool type. Always web_search.

store: optional boolean

Whether to store the forked session. Omission inherits the stored session’s setting.

ReturnsExpand Collapse

session: object { id }

The newly created Live session. Use its ID for session controls and sideband connections.

id: string

Opaque session identifier. Preserve the returned value unchanged, including its prefix.

transport: object { sdp, type }

WebRTC transport with the SDP answer.

sdp: string

Session Description Protocol message for the WebRTC connection.

minLength1

type: "webrtc"

The transport used for the Live session. Always webrtc.

Fork session

curl https://api.openai.com/v1/live/sessions/live_123/fork \
  -H "Authorization: Bearer $OPENAI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"session":{},"transport":{"type":"webrtc","sdp":"<SDP offer>"}}'

{
  "session": {
    "id": "id"
  },
  "transport": {
    "sdp": "x",
    "type": "webrtc"
  }
}

Returns Examples

{
  "session": {
    "id": "id"
  },
  "transport": {
    "sdp": "x",
    "type": "webrtc"
  }
}

Suggested

Suggested

Fork session

Path ParametersExpand Collapse

Body ParametersJSONExpand Collapse

ReturnsExpand Collapse

Fork session

Returns Examples