> ## Documentation Index
> Fetch the complete documentation index at: https://docs.langchain.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Join Run Stream

> Join a run stream. This endpoint streams output in real-time from a run similar to the /threads/__THREAD_ID__/runs/stream endpoint. If the run has been created with `stream_resumable=true`, the stream can be resumed from the last seen event ID.



## OpenAPI

````yaml /langsmith/agent-server-openapi.json get /threads/{thread_id}/runs/{run_id}/stream
openapi: 3.1.0
info:
  title: LangSmith Deployment
  version: 0.1.0
servers: []
security: []
tags:
  - name: Assistants
    description: An assistant is a configured instance of a graph.
  - name: Threads
    description: A thread contains the accumulated outputs of a group of runs.
  - name: Thread Runs
    description: >-
      A run is an invocation of a graph / assistant on a thread. It updates the
      state of the thread.
  - name: Stateless Runs
    description: >-
      A run is an invocation of a graph / assistant, with no state or memory
      persistence.
  - name: Crons
    description: >-
      A cron is a periodic run that recurs on a given schedule. The repeats can
      be isolated, or share state in a thread
  - name: Store
    description: >-
      Store is an API for managing persistent key-value store (long-term memory)
      that is available from any thread.
  - name: A2A
    description: >-
      Agent-to-Agent Protocol related endpoints for exposing assistants as
      A2A-compliant agents.
  - name: MCP
    description: >-
      Model Context Protocol related endpoints for exposing an agent as an MCP
      server.
  - name: System
    description: System endpoints for health checks, metrics, and server information.
paths:
  /threads/{thread_id}/runs/{run_id}/stream:
    get:
      tags:
        - Thread Runs
      summary: Join Run Stream
      description: >-
        Join a run stream. This endpoint streams output in real-time from a run
        similar to the /threads/__THREAD_ID__/runs/stream endpoint. If the run
        has been created with `stream_resumable=true`, the stream can be resumed
        from the last seen event ID.
      operationId: stream_run_http_threads__thread_id__runs__run_id__join_get
      parameters:
        - description: The ID of the thread.
          required: true
          schema:
            type: string
            format: uuid
            title: Thread Id
            description: The ID of the thread.
          name: thread_id
          in: path
        - description: The ID of the run.
          required: true
          schema:
            type: string
            format: uuid
            title: Run Id
            description: The ID of the run.
          name: run_id
          in: path
        - required: false
          schema:
            type: string
            title: Last Event ID
            description: >-
              The ID of the last event received. Set to -1 if you want to stream
              all events. Requires `stream_resumable=true` to be set when
              creating the run.
          name: Last-Event-ID
          in: header
        - required: false
          schema:
            type: string
            title: Stream Mode
            description: >-
              The mode to stream the run in. If not provided, the default mode
              will be used.
          name: stream_mode
          in: query
        - required: false
          schema:
            type: boolean
            title: Cancel On Disconnect
            description: If true, the run will be cancelled if the client disconnects.
            default: false
          name: cancel_on_disconnect
          in: query
      responses:
        '200':
          description: Success
          content:
            text/event-stream:
              schema:
                type: string
                description: |-
                  The server will send a stream of events in SSE format.

                  **Example event**:

                  id: 1

                  event: message

                  data: {}
        '404':
          description: Not Found
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
components:
  schemas:
    ErrorResponse:
      type: object
      required:
        - detail
      properties:
        detail:
          type: string
          description: Human-readable error message
      title: ErrorResponse
      description: Error response returned from the server

````