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

# Check Hub Handoff Session

> Whether this browser already holds the User's linked Contact session for a preview.

The admin Preview asks before it starts a ``preview`` handoff, and skips the
handoff only on ``signed_in: true``. Same User, Admin-origin and eligibility
checks as a ``preview`` launch (and the same refusals). The browser's Contact
refresh cookie is validated read-only, exactly like the hub's SSR read
(jti liveness, revocation watermark, token_version, handoff authority), and
never rotated. The answer names no Contact and grants nothing.



## OpenAPI

````yaml /openapi/mio-openapi.json post /api/v1/contact-auth/handoff/session-checks
openapi: 3.1.0
info:
  description: >-
    Production API reference for Membership.io. Use the authored guides for
    workflows and the generated endpoint pages for exact parameters and schemas.
  title: Membership.io API
  version: 0.1.0
servers:
  - description: Production
    url: https://api.member.dev
security:
  - bearerAuth: []
paths:
  /api/v1/contact-auth/handoff/session-checks:
    post:
      tags:
        - contact-auth
      summary: Check Hub Handoff Session
      description: >-
        Whether this browser already holds the User's linked Contact session for
        a preview.


        The admin Preview asks before it starts a ``preview`` handoff, and skips
        the

        handoff only on ``signed_in: true``. Same User, Admin-origin and
        eligibility

        checks as a ``preview`` launch (and the same refusals). The browser's
        Contact

        refresh cookie is validated read-only, exactly like the hub's SSR read

        (jti liveness, revocation watermark, token_version, handoff authority),
        and

        never rotated. The answer names no Contact and grants nothing.
      operationId: contact_auth.post_contact_auth_post_contact_auth_handoff_session_checks
      requestBody:
        content:
          application/vnd.api+json:
            schema:
              $ref: '#/components/schemas/HubHandoffSessionCheckEnvelope'
        required: true
      responses:
        '200':
          content:
            application/vnd.api+json:
              schema:
                $ref: '#/components/schemas/HubHandoffSessionCheckResponse'
          description: Successful Response
        '422':
          content:
            application/vnd.api+json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
          description: Validation Error
      security:
        - HTTPBearer: []
components:
  schemas:
    HubHandoffSessionCheckEnvelope:
      additionalProperties: false
      properties:
        data:
          $ref: '#/components/schemas/HubHandoffSessionCheckRequestResource'
      required:
        - data
      title: HubHandoffSessionCheckEnvelope
      type: object
    HubHandoffSessionCheckResponse:
      additionalProperties: false
      properties:
        data:
          $ref: '#/components/schemas/HubHandoffSessionCheckResource'
      required:
        - data
      title: HubHandoffSessionCheckResponse
      type: object
    HTTPValidationError:
      properties:
        detail:
          items:
            $ref: '#/components/schemas/ValidationError'
          title: Detail
          type: array
      title: HTTPValidationError
      type: object
    HubHandoffSessionCheckRequestResource:
      additionalProperties: false
      properties:
        attributes:
          $ref: '#/components/schemas/_HubHandoffSessionCheckRequestAttributes'
        type:
          const: hub_handoff_session_checks
          title: Type
          type: string
      required:
        - type
        - attributes
      title: HubHandoffSessionCheckRequestResource
      type: object
    HubHandoffSessionCheckResource:
      additionalProperties: false
      properties:
        attributes:
          $ref: '#/components/schemas/HubHandoffSessionCheckAttributes'
        id:
          title: Id
          type: string
        type:
          const: hub_handoff_session_checks
          default: hub_handoff_session_checks
          title: Type
          type: string
      required:
        - id
        - attributes
      title: HubHandoffSessionCheckResource
      type: object
    ValidationError:
      properties:
        ctx:
          title: Context
          type: object
        input:
          title: Input
        loc:
          items:
            anyOf:
              - type: string
              - type: integer
          title: Location
          type: array
        msg:
          title: Message
          type: string
        type:
          title: Error Type
          type: string
      required:
        - loc
        - msg
        - type
      title: ValidationError
      type: object
    _HubHandoffSessionCheckRequestAttributes:
      additionalProperties: false
      properties:
        hub_id:
          maxLength: 36
          minLength: 1
          title: Hub Id
          type: string
      required:
        - hub_id
      title: _HubHandoffSessionCheckRequestAttributes
      type: object
    HubHandoffSessionCheckAttributes:
      additionalProperties: false
      properties:
        signed_in:
          description: >-
            True only when this browser's Contact refresh cookie is a live
            session of the Contact linked to the calling User, and that Contact
            could be signed in to this hub's preview by a handoff. Names no
            Contact; grants nothing.
          title: Signed In
          type: boolean
      required:
        - signed_in
      title: HubHandoffSessionCheckAttributes
      type: object
  securitySchemes:
    bearerAuth:
      bearerFormat: JWT or mio_sk API key
      description: >-
        Send platform JWTs, contact JWTs, or team API keys as `Authorization:
        Bearer <token>`.
      scheme: bearer
      type: http
    HTTPBearer:
      scheme: bearer
      type: http

````

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