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

# Dry-run a dynamic transfer-destination lookup (no persist)

> Resolve a transfer target's destination exactly as the voice host would.

Powers the authoring UI's "what number would this resolve to?" preview: the
request's ``input_mapping`` is rendered against sample ``context_vars`` and
executed through the same shared lookup core as a live transfer (same
renderer, same revalidation gates, same extraction), so preview and runtime
cannot drift. Verifies the revision belongs to the caller's org AND to
``tool_id`` (404 otherwise). Persists nothing; API inputs, response bodies,
and the resolved destination are never logged.



## OpenAPI

````yaml /api-reference/openapi.json post /v1/tools/{tool_id}/revisions/{revision_id}/preview-transfer-destination
openapi: 3.1.0
info:
  title: Feather API
  description: >-
    Unified customer experience platform API. Manages identity, conversations,
    memory, agents, procedures, policies, model routing, knowledge bases,
    integrations, and runtime execution.
  version: 1.87.0
servers:
  - url: https://api-sandbox.featherhq.com
    description: Sandbox
  - url: http://localhost:8000
    description: Local dev
security: []
paths:
  /v1/tools/{tool_id}/revisions/{revision_id}/preview-transfer-destination:
    post:
      tags:
        - tools
      summary: Dry-run a dynamic transfer-destination lookup (no persist)
      description: >-
        Resolve a transfer target's destination exactly as the voice host would.


        Powers the authoring UI's "what number would this resolve to?" preview:
        the

        request's ``input_mapping`` is rendered against sample ``context_vars``
        and

        executed through the same shared lookup core as a live transfer (same

        renderer, same revalidation gates, same extraction), so preview and
        runtime

        cannot drift. Verifies the revision belongs to the caller's org AND to

        ``tool_id`` (404 otherwise). Persists nothing; API inputs, response
        bodies,

        and the resolved destination are never logged.
      operationId: previewTransferDestination
      parameters:
        - name: tool_id
          in: path
          required: true
          schema:
            type: string
            format: uuid
            title: Tool Id
        - name: revision_id
          in: path
          required: true
          schema:
            type: string
            format: uuid
            title: Revision Id
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/TransferDestinationPreviewRequest'
      responses:
        '200':
          description: Successful Response
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/TransferDestinationPreviewResponse'
        '400':
          description: Bad request
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '401':
          description: Authentication required
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '404':
          description: Resource not found
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ErrorResponse'
        '422':
          description: Validation Error
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/HTTPValidationError'
      security:
        - APIKeyHeader: []
components:
  schemas:
    TransferDestinationPreviewRequest:
      properties:
        input_mapping:
          additionalProperties: true
          type: object
          title: Input Mapping
        response_path:
          type: string
          title: Response Path
        context_vars:
          additionalProperties: true
          type: object
          title: Context Vars
      additionalProperties: false
      type: object
      required:
        - response_path
      title: TransferDestinationPreviewRequest
      description: >-
        Authoring dry-run of a dynamic transfer-destination lookup.


        Renders ``input_mapping`` against sample ``context_vars`` and drives the

        referenced api_call revision through the SAME shared lookup core the
        voice

        host uses at transfer time — so the preview and a live transfer cannot

        drift. Nothing is persisted; API inputs, response bodies, and the
        resolved

        destination are never logged.
    TransferDestinationPreviewResponse:
      properties:
        resolved:
          type: boolean
          title: Resolved
        destination:
          anyOf:
            - type: string
            - type: 'null'
          title: Destination
        subcode:
          anyOf:
            - type: string
            - type: 'null'
          title: Subcode
        missing_inputs:
          items:
            type: string
          type: array
          title: Missing Inputs
        problems:
          items:
            $ref: '#/components/schemas/TransferDestinationPreviewProblem'
          type: array
          title: Problems
      type: object
      required:
        - resolved
      title: TransferDestinationPreviewResponse
      description: >-
        Result of a dynamic transfer-destination preview.


        ``resolved`` is ``True`` iff a dialable destination was extracted from
        the

        lookup response. Otherwise ``subcode`` carries the runtime failure
        reason;

        ``missing_inputs`` and ``problems`` surface pre-execution (render /
        shape)

        failures independently.
    ErrorResponse:
      properties:
        error:
          type: string
          title: Error
        message:
          type: string
          title: Message
        retryable:
          anyOf:
            - type: boolean
            - type: 'null'
          title: Retryable
        retry_after:
          anyOf:
            - type: integer
            - type: 'null'
          title: Retry After
      type: object
      required:
        - error
        - message
      title: ErrorResponse
      description: Standard error response returned by all API error handlers.
    HTTPValidationError:
      properties:
        detail:
          items:
            $ref: '#/components/schemas/ValidationError'
          type: array
          title: Detail
      type: object
      title: HTTPValidationError
    TransferDestinationPreviewProblem:
      properties:
        kind:
          type: string
          title: Kind
        message:
          type: string
          title: Message
      type: object
      required:
        - kind
        - message
      title: TransferDestinationPreviewProblem
      description: One structured problem from a preview run (pure authoring finding).
    ValidationError:
      properties:
        loc:
          items:
            anyOf:
              - type: string
              - type: integer
          type: array
          title: Location
        msg:
          type: string
          title: Message
        type:
          type: string
          title: Error Type
        input:
          title: Input
        ctx:
          type: object
          title: Context
      type: object
      required:
        - loc
        - msg
        - type
      title: ValidationError
  securitySchemes:
    APIKeyHeader:
      type: apiKey
      in: header
      name: x-api-key

````