Changes a classic proposal while it is a draft or sent; accepted and rejected proposals are locked.

Send the fields inside a proposal object: title, status, notes, valid_until, tax_rate, target_margin_pct and address_id, and proposal_line_items_attributes to add, change (with id) or remove (with _destroy: true) lines. Each line takes description, category, tier, quantity, unit, product_unit_id, unit_price, unit_cost, product_id and position.

The token's role must be allowed to prepare estimates, and must either have access to all records or be the sales rep assigned to the deal.