Add spec, plan, and tasks for 016-cancel-event feature

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

specs/016-cancel-event/contracts/patch-event-endpoint.yaml

@@ -0,0 +1,78 @@
+# OpenAPI additions for Cancel Event feature
+# To be merged into backend/src/main/resources/openapi/api.yaml
+
+# PATCH method added to existing /events/{eventToken} path
+# Under paths./events/{eventToken}:
+
+# --- Add PATCH method to existing path ---
+# /events/{eventToken}:
+#   patch:
+#     operationId: patchEvent
+#     summary: Update an event (currently: cancel)
+#     description: |
+#       Partial update of an event resource. Currently the only supported operation
+#       is cancellation (setting cancelled to true). Requires the organizer token.
+#       Cancellation is irreversible.
+#     tags: [Events]
+#     parameters:
+#       - $ref: '#/components/parameters/EventToken'
+#     requestBody:
+#       required: true
+#       content:
+#         application/json:
+#           schema:
+#             $ref: '#/components/schemas/PatchEventRequest'
+#     responses:
+#       '204':
+#         description: Event updated successfully
+#       '403':
+#         description: Invalid organizer token
+#         content:
+#           application/json:
+#             schema:
+#               $ref: '#/components/schemas/ErrorResponse'
+#       '404':
+#         description: Event not found
+#         content:
+#           application/json:
+#             schema:
+#               $ref: '#/components/schemas/ErrorResponse'
+#       '409':
+#         description: Event is already cancelled
+#         content:
+#           application/json:
+#             schema:
+#               $ref: '#/components/schemas/ErrorResponse'
+
+# --- New schemas ---
+
+# PatchEventRequest:
+#   type: object
+#   required: [organizerToken, cancelled]
+#   properties:
+#     organizerToken:
+#       type: string
+#       format: uuid
+#       description: The organizer token proving ownership of the event
+#       example: "550e8400-e29b-41d4-a716-446655440001"
+#     cancelled:
+#       type: boolean
+#       description: Set to true to cancel the event (irreversible)
+#       example: true
+#     cancellationReason:
+#       type: string
+#       maxLength: 2000
+#       description: Optional cancellation reason
+#       example: "Unfortunately the venue is no longer available."
+
+# --- Extended schema: GetEventResponse ---
+# Add to existing GetEventResponse properties:
+#   cancelled:
+#     type: boolean
+#     description: Whether the event has been cancelled
+#     example: false
+#   cancellationReason:
+#     type: string
+#     nullable: true
+#     description: Reason for cancellation, if provided
+#     example: null