Updates an existing contract.

Currency fields (e.g., amount) can be numbers ("amount": 1500, uses org default currency) or objects to set a different currency: "amount": { "value": 23000000, "currency": "EUR" }. Cannot set currency as a top-level field.

Optional lineItems are appended to the contract's existing line items (each needs a description; the same optional value fields as on create). Items cannot carry an id (400), existing items are never modified or removed here, and omitting lineItems leaves them unchanged. Removing a line item is done in the Torii web app. Read them back with GET /contracts/{idContract}?fields=lineItems.

• Rate limit: 400 requests per minute