Stream a thread run

Start a run on a thread and stream output as server-sent events. The request must use agent_id; assistant_id is reserved for server-side forwarding and is rejected.

POST /threads/{threadID}/runs/stream

Stream a thread run

cURL

curl --request POST \
  --url https://api.smith.langchain.com/v1/deepagents/threads/{threadID}/runs/stream \
  --header 'Content-Type: application/json' \
  --header 'X-Api-Key: <api-key>' \
  --data '
{
  "agent_id": "11111111-1111-1111-1111-111111111111",
  "messages": [
    {
      "role": "user",
      "content": "Research recent approaches to agent memory and summarize the main tradeoffs."
    }
  ],
  "stream_mode": [
    "updates"
  ],
  "stream_subgraphs": true,
  "user_timezone": "America/Los_Angeles"
}
'

200

Example

"<string>"

Authorizations

X-Api-Key · string · header · default: LANGSMITH_API_KEY · required

Path Parameters

threadID · string · required

Thread ID.

Body

application/json

agent_id · string<uuid> · required

Managed Deep Agent ID. The server forwards this upstream as assistant_id.

messages · object[] · required

Input messages for the run.

Minimum array length: 1

Show child attributes

stream_mode · enum<string>[]

Stream modes to return.

Available options: values, updates, messages-tuple

stream_subgraphs · boolean

Whether to stream subgraph events.

user_timezone · string

IANA timezone name (for example, America/Los_Angeles) for this run. The runtime uses it to inject a localized current-date line into the agent's system prompt, so the agent reasons about dates in the user's local time. Optional. Defaults to the timezone stamped on the agent (or UTC if none was set); invalid values fall back to UTC.

Example:

"America/Los_Angeles"

Response

200

text/event-stream

Server-sent event stream.

The response is of type string.