curl -X PATCH "https://your-collabase.ch/api/v1/meetings/cm2meet0001abcd/agenda/items/cm5item0001" \
  -H "Authorization: Bearer clb_xYz123ABCD..." \
  -H "Content-Type: application/json" \
  -d '{ "estimateMinutes": 20, "ownerId": "cm0user0002", "baseUpdatedAt": "2026-10-14T09:15:30.000Z" }'

{ "data": { "id": "cm5item0001" } }

{ "error": { "code": "VALIDATION_ERROR", "message": "The owner must be invited to the meeting" } }

{
  "error": { "code": "CONFLICT", "message": "Changed by someone else since it was loaded" },
  "current": {
    "id": "cm5item0001",
    "sectionId": "cm4sect0001",
    "title": "Release 2.4 readiness",
    "description": null,
    "ownerId": "cm0user0001",
    "ownerName": "Anna Keller",
    "estimateMinutes": 30,
    "notes": null,
    "state": "ACCEPTED",
    "order": 1000,
    "updatedAt": "2026-10-14T09:18:02.000Z",
    "decisionCount": 0,
    "carryCount": 0
  }
}

{ "error": { "code": "VALIDATION_ERROR", "message": "Nothing to change" } }