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

# Update an event

> Partial update; JSON null clears a field (date, recur, start_time clears both times, notes, category, art). Sending recur clears date and vice versa, so schedule kinds swap cleanly.



## OpenAPI

````yaml https://youragentcal.com/openapi.json patch /v1/calendars/{calendarId}/events/{eventId}
openapi: 3.1.0
info:
  title: AgentCal API
  version: 0.5.0
  description: >-
    The AgentCal HTTP API: calendars for AI agents. Agents mint their own
    identity and credentials, create calendars, write events, share access with
    humans and other agents, and compose calendars as layers. Plain JSON over
    HTTPS; no SDK required.


    Agent-readable quickstart: https://youragentcal.com/start.md
  contact:
    url: https://youragentcal.com
servers:
  - url: https://youragentcal.com
security:
  - agentToken: []
tags:
  - name: Identity
    description: >-
      Minting and credentials. An agent mints once, keeps the token, and can
      manage extra keys.
  - name: Calendars
    description: >-
      Create calendars and manage their settings (name, slug, timezone,
      visibility, purpose, lenses).
  - name: Events
    description: One-off, recurring, and someday events on a calendar.
  - name: Grants
    description: 'Per-calendar access for other agents: owner, writer, or reader.'
  - name: Access requests
    description: Ask for access to someone else's calendar; owners approve or deny.
  - name: Share views
    description: Filtered, capability-URL projections of a calendar at /v/{slug}.
  - name: Layers
    description: Attach other calendars as layers to compose a project calendar.
paths:
  /v1/calendars/{calendarId}/events/{eventId}:
    patch:
      tags:
        - Events
      summary: Update an event
      description: >-
        Partial update; JSON null clears a field (date, recur, start_time clears
        both times, notes, category, art). Sending recur clears date and vice
        versa, so schedule kinds swap cleanly.
      operationId: updateEvent
      parameters:
        - $ref: '#/components/parameters/CalendarId'
        - $ref: '#/components/parameters/EventId'
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/EventPatch'
      responses:
        '200':
          description: Updated event.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Event'
        '400':
          $ref: '#/components/responses/BadRequest'
        '401':
          $ref: '#/components/responses/Unauthorized'
        '403':
          $ref: '#/components/responses/Forbidden'
        '404':
          $ref: '#/components/responses/NotFound'
components:
  parameters:
    CalendarId:
      name: calendarId
      in: path
      required: true
      schema:
        type: string
      description: cal_… public id.
    EventId:
      name: eventId
      in: path
      required: true
      schema:
        type: string
      description: evt_… public id.
  schemas:
    EventPatch:
      description: >-
        Same fields as EventInput, all optional; JSON null clears date, recur,
        start_time (clears both times), notes, category, or art.
      type: object
      properties:
        name:
          type: string
        date:
          type:
            - string
            - 'null'
          format: date
        recur:
          type:
            - object
            - 'null'
        start_time:
          type:
            - string
            - 'null'
        end_time:
          type:
            - string
            - 'null'
        notes:
          type:
            - string
            - 'null'
        category:
          type:
            - string
            - 'null'
        art:
          type:
            - string
            - 'null'
    Event:
      type: object
      properties:
        id:
          type: string
          examples:
            - evt_…
        name:
          type: string
        date:
          type: string
          format: date
        recur:
          type: object
        start_time:
          type: string
        end_time:
          type: string
        notes:
          type: string
        category:
          type: string
        art:
          type: string
        created_by:
          type: string
          description: agt_… id of the creating agent.
        created_by_name:
          type: string
        created_at:
          type: string
          format: date-time
        updated_at:
          type: string
          format: date-time
    Error:
      type: object
      properties:
        error:
          type: object
          properties:
            code:
              type: string
              examples:
                - invalid_request
                - unauthorized
                - insufficient_scope
                - not_found
                - slug_taken
                - last_owner
                - key_taken
            message:
              type: string
            details:
              type: object
              description: Optional extras, e.g. available slug suggestions on slug_taken.
              additionalProperties: true
  responses:
    BadRequest:
      description: >-
        Invalid request (invalid_json, invalid_request, invalid_event,
        missing_idempotency_key, last_owner, layer_depth…).
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    Unauthorized:
      description: Missing or invalid bearer token.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    Forbidden:
      description: >-
        The credential lacks a required scope, or the agent lacks a sufficient
        grant.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    NotFound:
      description: No such resource.
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
  securitySchemes:
    agentToken:
      type: http
      scheme: bearer
      description: >-
        Agent token from POST /v1/mint (format ac_agent_…). Scopes: agent:read,
        calendar:read, calendar:write, grants:manage.

````