feat(openapi3): add @pageIndex decorator support for x-ms-list-page-index extension

[Copilot]

The OpenAPI3 importer now recognizes the x-ms-list-page-index extension on parameters and generates the corresponding @pageIndex decorator in TypeSpec output.

Changes

• Importer enhancement: Modified getParameterDecorators() to detect x-ms-list-page-index: true and emit @pageIndex decorator
• Test coverage: Added 4 test cases verifying decorator emission for true/false/missing extension values

Example

OpenAPI input:

parameters:
  - name: idx
    in: query
    required: true
    schema:
      type: integer
      format: int32
    x-ms-list-page-index: true

Generated TypeSpec:

@extension("x-ms-list-page-index", true)
@pageIndex
@query
idx: int32

The extension decorator is preserved for round-trip fidelity while the semantic @pageIndex decorator enables proper paging behavior in downstream emitters.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Add support for adding the pageIndex decorator based on the relevant openapi extension</issue_title>
<issue_description>### Clear and concise description of the problem

Related https://github.com/microsoft/openai-openapi-pr/issues/568

Based on the following OpenAPI description, we should get the following TypeSpec definition imported

openapi: 3.0.0
info:
  title: Widget Service
  version: 0.0.0
tags:
  - name: Widgets
paths:
  /widgets:
    get:
      operationId: Widgets_list
      description: List widgets
      parameters:
        - name: idx
          in: query
          required: true
          schema:
            type: integer
            format: int32
          #this is the extension that matters
          x-ms-list-page-index: true
          explode: false
      responses:
        '200':
          description: The request has succeeded.
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Widget'
        default:
          description: An unexpected error response.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
      tags:
        - Widgets
    post:
      operationId: Widgets_create
      description: Create a widget
      parameters: []
      responses:
        '200':
          description: The request has succeeded.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Widget'
        default:
          description: An unexpected error response.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
      tags:
        - Widgets
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/Widget'
  /widgets/{id}:
    get:
      operationId: Widgets_read
      description: Read widgets
      parameters:
        - name: id
          in: path
          required: true
          schema:
            type: string
            readOnly: true
      responses:
        '200':
          description: The request has succeeded.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Widget'
        default:
          description: An unexpected error response.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
      tags:
        - Widgets
    patch:
      operationId: Widgets_update
      description: Update a widget
      parameters:
        - name: id
          in: path
          required: true
          schema:
            type: string
            readOnly: true
      responses:
        '200':
          description: The request has succeeded.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Widget'
        default:
          description: An unexpected error response.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
      tags:
        - Widgets
      requestBody:
        required: true
        content:
          application/merge-patch+json:
            schema:
              $ref: '#/components/schemas/WidgetMergePatchUpdate'
    delete:
      operationId: Widgets_delete
      description: Delete a widget
      parameters:
        - name: id
          in: path
          required: true
          schema:
            type: string
            readOnly: true
      responses:
        '204':
          description: 'There is no content to send for this request, but the headers may be useful. '
        default:
          description: An unexpected error response.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
      tags:
        - Widgets
  /widgets/{id}/analyze:
    post:
      operationId: Widgets_analyze
      description: Analyze a widget
      parameters:
        - name: id
          in: path
          required: true
          schema:
            type: string
            readOnly: true
      responses:
        '200':
          description: The request has succeeded.
          content:
            text/plain:
              schema:
                type: string
        default:
          description: An unexpected error response.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
      tags:
        - Widgets
components:
  schemas:
    Error:
      type: object
      required:
        - code
        - message
      properties:
        code:
          type: integer
          format: int32
        message:
        ...

</details>



<!-- START COPILOT CODING AGENT SUFFIX -->

- Fixes microsoft/typespec#9610

<!-- START COPILOT CODING AGENT TIPS -->
---

💬 We'd love your input! Share your thoughts on Copilot coding agent in our [2 minute survey](https://gh.io/copilot-coding-agent-survey).

[pkg-pr-new]

Open in StackBlitz

npm i https://pkg.pr.new/microsoft/typespec/@typespec/openapi@9611

npm i https://pkg.pr.new/microsoft/typespec/@typespec/openapi3@9611

commit: 29576cc

[github-actions]

All changed packages have been documented.

• ✅ @typespec/openapi3

Show changes

@typespec/openapi3 - feature ✏️

importer - Add support for x-ms-list-page-index extension to add @pageIndex decorator

[azure-sdk]

You can try these changes here

🛝 Playground	🌐 Website	🛝 VSCode Extension