E039: Link contact to entity

POST /api/contacts/:id/links

Associates an existing contact with a customer, vendor, or other entity. Triggered from Customer Detail or Vendor Detail, "Add contact" with an existing contact.

Authentication

Standard tenant route. Requires Authorization: Bearer <firebase-id-token> and X-Org-Id: <org-id>. Access: Member.

Request

{
  "entityType": "customer",
  "entityId": "uuid",
  "role": "billing",
  "isPrimary": true
}

entityType is "customer" or "vendor" (the polymorphic set in v1.0.0).

Response — 201 Created

{
  "id": "uuid",
  "contactId": "uuid",
  "entityType": "customer",
  "entityId": "uuid",
  "role": "billing",
  "isPrimary": true,
  "createdAt": "..."
}

Errors

HTTP	code	Condition
404	not_found	Contact or entity not found.
409	invalid_transition	Contact already linked to that entity with the same role.
422	validation_failed	Shape invalid.

Workflow

Calls W039 Link contact to entity.