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

# Stream a chat turn

> SSE tail of a chat turn.

`text/event-stream`. Resume with `Last-Event-ID`. This is the read half of [Start a chat turn](/api-reference/chats/start-turn).


## OpenAPI

````yaml GET /api/v2/chats/{thread_id}/messages/{msg_id}/stream/
openapi: 3.1.0
info:
  title: Abacus Docs API
  version: 1.0.0
  description: |
    REST + SSE surface for Abacus Docs on the same host as the web app
    (`https://abacusdocs.com`). Paths are `/api/v2/…`.

    Authenticate with an organisation API key (`sk-abacus-*`) as a Bearer
    token, or an Auth0 access token. Cross-tenant reads return **404**, not
    403. Page-based lists use `?page=` and `?page_size=`.

    Extraction, reprocess, schema tests, and chat turns spend credits.
    See the help centre Credits pages for rates.
  contact:
    name: Abacus Docs
    url: https://abacusdocs.com/contact
servers:
  - url: https://abacusdocs.com
    description: Production (Extract)
security: []
paths:
  /api/v2/chats/{thread_id}/messages/{msg_id}/stream/:
    get:
      tags:
        - v2/chats
      summary: Stream a chat turn over SSE
      description: >-
        When durable turns are enabled (AD-404): tails the Redis Stream for
        `msg_id` (= `turn_id`). Each frame carries the Redis entry id as SSE
        `id:` so EventSource can resume via `Last-Event-ID`. Concurrent
        subscribers are allowed. Expired streams synthesize a terminal sequence
        from the ChatMessage row. When the flag is off: consumes the legacy
        one-shot buffer and runs the graph inline.
      operationId: v2_chats_messages_stream_retrieve
      parameters:
        - in: query
          name: format
          schema:
            type: string
            enum:
              - event-stream
              - json
        - in: path
          name: msg_id
          schema:
            type: string
          required: true
        - in: path
          name: thread_id
          schema:
            type: string
          required: true
      responses:
        '200':
          content:
            application/json:
              schema:
                type: string
                format: binary
            text/event-stream:
              schema:
                type: string
                format: binary
          description: ''
        '404':
          content:
            application/json:
              schema:
                type: object
                additionalProperties: {}
            text/event-stream:
              schema:
                type: object
                additionalProperties: {}
          description: ''
      security:
        - extractApiKey: []
        - bearerAuth: []
        - cookieAuth: []
components:
  securitySchemes:
    extractApiKey:
      type: http
      scheme: bearer
      bearerFormat: API Key
      description: |
        Organisation API key from Settings → API / `/api/keys/`. The secret is
        shown once. Send `Authorization: Bearer sk-abacus-…`. One active key
        per organisation. Ingest (`/api/v2/ingest/*`) refuses API keys — that
        surface is Auth0-only with `ingest:read` / `ingest:write` scopes.
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: JWT
      description: >
        Auth0 access token for a signed-in user. Send `Authorization: Bearer
        <token>`.

        The SPA and desktop agent use this. Prefer an organisation API key for

        server-to-server integrations.
    cookieAuth:
      type: apiKey
      in: cookie
      name: sessionid
      description: |
        Django session cookie from a browser login. Present so the web app can
        call `/api/v2` without a header. Do not rely on this for integrations.

````