Logs a new activity record of the given activity type against exactly one parent entity.

Parent entity. At least one of employerId, leadId, workflowId, customerId or meetingId must be set. If several are set, only the first non-null one in that order is used (e.g. employerId wins over customerId). When the parent is a lead, the lead's customer is also linked; when it is a workflow or meeting, the related customer (and, for a meeting, lead) is linked as well.

Authorization. The caller must be able to access the parent entity and hold the user permission matching its type: employers:write, leads:update, workflows:update, customers:update or meetings:update. No OAuth2 scope beyond a valid token is required.

Content. htmlContent is sanitized (formatting, blocks, styles, images, links and tables are kept; scripts and other markup are stripped). A plain-text copy is stored for search. jsonContent, if set, is stored alongside it. mentions may only reference users of the caller's tenant.

Side effects. Publishes an ActivityCreated event (which notifies the mentioned users). The response is 200 OK with the created record.

Errors. 404 if the activity type, the parent entity or a mentioned user does not exist in the caller's tenant; 400 if the request is invalid (no parent entity, missing type, empty content, invalid mentions), and 400 with error code 40000 if the caller lacks the required permission or access to the parent entity.

{
  "typeId": "6f1c2a7e-3b4d-4e8f-9a01-2c3d4e5f6a7b",
  "employerId": "9a8b7c6d-5e4f-4a3b-8c2d-1e0f9a8b7c6d",
  "customerId": "b2e4c6d8-1a3b-4c5d-8e7f-9a0b1c2d3e4f",
  "leadId": "0d9e8f7a-6b5c-4d3e-8f2a-1b0c9d8e7f6a",
  "workflowId": "4e5f6a7b-8c9d-4e0f-a1b2-c3d4e5f6a7b8",
  "meetingId": "7b8c9d0e-1f2a-4b3c-9d4e-5f6a7b8c9d0e",
  "htmlContent": "<p>Spoke with the customer about renewing the car insurance policy.</p>",
  "mentions": [
    {
      "type": "user",
      "entityId": "123e4567-e89b-12d3-a456-426614174000",
      "label": "John Doe",
      "order": 0
    }
  ]
}

{
  "id": "3c8a1f2e-5d4b-4a9c-b7e6-1f2a3b4c5d6e",
  "typeId": "6f1c2a7e-3b4d-4e8f-9a01-2c3d4e5f6a7b",
  "employerId": "9a8b7c6d-5e4f-4a3b-8c2d-1e0f9a8b7c6d",
  "customerId": "b2e4c6d8-1a3b-4c5d-8e7f-9a0b1c2d3e4f",
  "leadId": "0d9e8f7a-6b5c-4d3e-8f2a-1b0c9d8e7f6a",
  "workflowId": "4e5f6a7b-8c9d-4e0f-a1b2-c3d4e5f6a7b8",
  "meetingId": "7b8c9d0e-1f2a-4b3c-9d4e-5f6a7b8c9d0e",
  "activityDate": "2026-03-15T09:30:00Z",
  "htmlContent": "<p>Spoke with the customer about renewing the car insurance policy.</p>",
  "lastEditedAt": "2026-03-16T14:05:00Z",
  "lastEditedBy": "5d6e7f8a-9b0c-4d1e-a2f3-4a5b6c7d8e9f"
}