> ## Documentation Index
> Fetch the complete documentation index at: https://docs.hill90.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Add or remove agent participants

> Add or remove agent participants from a group thread. Only the thread owner
or admin can modify participants. Removing an agent sets left_at and marks
any pending messages from that agent as error.




## OpenAPI

````yaml /ai-app/openapi.yaml put /chat/threads/{id}/participants
openapi: 3.0.3
info:
  title: Hill90 API
  description: Hill90 platform API — agent management and lifecycle operations.
  version: 0.1.0
servers:
  - url: /
    description: Relative (behind Traefik reverse proxy)
security: []
paths:
  /chat/threads/{id}/participants:
    parameters:
      - name: id
        in: path
        required: true
        schema:
          type: string
          format: uuid
    put:
      summary: Add or remove agent participants
      description: >
        Add or remove agent participants from a group thread. Only the thread
        owner

        or admin can modify participants. Removing an agent sets left_at and
        marks

        any pending messages from that agent as error.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: object
              properties:
                add:
                  type: array
                  items:
                    type: string
                    format: uuid
                  description: Agent UUIDs to add
                remove:
                  type: array
                  items:
                    type: string
                    format: uuid
                  description: Agent UUIDs to remove
      responses:
        '200':
          description: Updated participant list
          content:
            application/json:
              schema:
                type: object
                properties:
                  participants:
                    type: array
                    items:
                      type: object
        '400':
          description: Exceeds max agents per group
        '403':
          description: Elevated scope requires admin role
        '404':
          description: Thread not found or not owner
      security:
        - bearerAuth: []
components:
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: JWT

````