Ask for the cruise, not the date
POST /api/v1/coaches/availability now takes a sailing_id instead of a date, and answers with exactly two results: that sailing's outbound coach and its inbound coach, each priced on its own with its own rate_reference and labelled leg. No other cruises, no other dates, no other routes. Every departure's sailings now carry a sailing_id, and passing the same one to /bookings/quote takes the coach home from the sailing itself. This matters when one run feeds two cruises that come home on different days: a return_date names a coach, not a cruise, so it could not tell them apart. Add sailing to a normal date search to narrow it to one cruise.
See the reference