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

# Replace an extension namespace

> Replaces the JSON payload for one extension namespace on the item. Body size is capped at 100KB — over-size payloads belong in a custom type with attachments or a `derived-from` edge, not in an extension. Requires `write` on the namespace in `extension_permissions`. Reserved namespaces (e.g. `connection.runtime`) carry additional write constraints — see the reserved-namespace list in the server's extension policy.



## OpenAPI

````yaml /openapi.json put /items/{id}/extensions/{namespace}
openapi: 3.1.0
info:
  title: Marfa API
  version: 4.2.0
  description: Typed data layer for structured personal data
servers: []
security: []
paths:
  /items/{id}/extensions/{namespace}:
    put:
      tags:
        - Extensions
      summary: Replace an extension namespace
      description: >-
        Replaces the JSON payload for one extension namespace on the item. Body
        size is capped at 100KB — over-size payloads belong in a custom type
        with attachments or a `derived-from` edge, not in an extension. Requires
        `write` on the namespace in `extension_permissions`. Reserved namespaces
        (e.g. `connection.runtime`) carry additional write constraints — see the
        reserved-namespace list in the server's extension policy.
      parameters:
        - schema:
            type: string
          required: true
          name: id
          in: path
        - schema:
            type: string
          required: true
          name: namespace
          in: path
      requestBody:
        content:
          application/json:
            schema:
              type: object
              additionalProperties:
                nullable: true
      responses:
        '200':
          description: Updated extensions
          content:
            application/json:
              schema:
                type: object
                properties:
                  extensions:
                    type: object
                    additionalProperties:
                      type: object
                      additionalProperties:
                        nullable: true
                required:
                  - extensions
        '400':
          description: Validation error
          content:
            application/json:
              schema:
                type: object
                properties:
                  error:
                    type: object
                    properties:
                      code:
                        type: string
                        enum:
                          - validation_error
                          - missing_required_field
                          - invalid_id
                      message:
                        type: string
                      details:
                        type: object
                        additionalProperties:
                          nullable: true
                    required:
                      - code
                      - message
                required:
                  - error
        '401':
          description: Unauthorized
          content:
            application/json:
              schema:
                type: object
                properties:
                  error:
                    type: object
                    properties:
                      code:
                        type: string
                        enum:
                          - unauthorized
                      message:
                        type: string
                      details:
                        type: object
                        additionalProperties:
                          nullable: true
                    required:
                      - code
                      - message
                required:
                  - error
        '403':
          description: No write access to namespace
          content:
            application/json:
              schema:
                type: object
                properties:
                  error:
                    type: object
                    properties:
                      code:
                        type: string
                        enum:
                          - forbidden
                      message:
                        type: string
                      details:
                        type: object
                        additionalProperties:
                          nullable: true
                    required:
                      - code
                      - message
                required:
                  - error
        '404':
          description: Item not found
          content:
            application/json:
              schema:
                type: object
                properties:
                  error:
                    type: object
                    properties:
                      code:
                        type: string
                        enum:
                          - item_not_found
                      message:
                        type: string
                      details:
                        type: object
                        additionalProperties:
                          nullable: true
                    required:
                      - code
                      - message
                required:
                  - error
      security:
        - bearerAuth: []
components:
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      bearerFormat: API Key or OAuth Token
      description: Pass an API key (marfa_k1_...) or OAuth access token (marfa_at_...)

````