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

# Get the preview

> The latest generated preview — the proposed output, sheet-per-template. 404 until a generate/update run has produced one.



## OpenAPI

````yaml /api-reference/openapi.json get /migrations/{migration_id}/preview
openapi: 3.1.0
info:
  title: Vern Migration API
  version: 1.0.0
  description: >-
    Run Vern as a headless migration engine. Create a migration, upload a
    customer's files, run the managed agent to generate a preview, then execute
    and export clean data. See the Migration API guides for concepts and
    walkthroughs.
servers:
  - url: https://app.vern.so/api/v1
security:
  - apiKey: []
tags:
  - name: Catalog
    description: Discover the sources and templates you set up in the Vern UI.
  - name: Migrations
    description: Create a migration workspace and upload a customer's files.
  - name: Runs
    description: 'Drive the managed agent: generate, refine, execute, answer, and observe.'
  - name: Export
    description: Download a migration's validated data as CSV.
paths:
  /migrations/{migration_id}/preview:
    parameters:
      - $ref: '#/components/parameters/MigrationId'
    get:
      tags:
        - Runs
      summary: Get the preview
      description: >-
        The latest generated preview — the proposed output, sheet-per-template.
        404 until a generate/update run has produced one.
      operationId: getPreview
      responses:
        '200':
          description: The current preview.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Preview'
              example:
                status: awaiting_approval
                templates:
                  - slug: contacts
                    name: Contacts
                sheets:
                  - template:
                      slug: contacts
                      name: Contacts
                    rows:
                      - - Email
                        - First Name
                        - Last Name
                      - - jane@acme.com
                        - Jane
                        - Doe
                    invalid_cells: []
        '401':
          $ref: '#/components/responses/Unauthorized'
        '404':
          $ref: '#/components/responses/NotFound'
        '429':
          $ref: '#/components/responses/RateLimited'
components:
  parameters:
    MigrationId:
      name: migration_id
      in: path
      required: true
      description: The migration ID returned by Create a migration.
      schema:
        type: string
        format: uuid
      example: c0a8012e-4f1b-4d3a-9b2c-7e6f5a4b3c2d
  schemas:
    Preview:
      type: object
      properties:
        status:
          type: string
          example: awaiting_approval
        templates:
          type: array
          items:
            type: object
            properties:
              slug:
                type: string
              name:
                type: string
        sheets:
          type: array
          items:
            type: object
            properties:
              template:
                type: object
                properties:
                  slug:
                    type: string
                  name:
                    type: string
              rows:
                type: array
                items:
                  type: array
                  items:
                    type: string
                description: Rows as a grid, header row first.
              invalid_cells:
                type: array
                items: {}
    Error:
      type: object
      properties:
        error:
          type: string
          description: A human-readable error message.
      required:
        - error
  responses:
    Unauthorized:
      description: API key missing, malformed, or revoked.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    NotFound:
      description: The referenced resource isn't in your account.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    RateLimited:
      description: Rate limit hit — back off and retry.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
          example:
            error: Too many requests
  securitySchemes:
    apiKey:
      type: apiKey
      in: header
      name: x-api-key
      description: Your Vern API key. Create one at Settings → API keys.

````