Simple really.
I had a query with the flight so I phoned a very helpful AI rep in the UK. Told her the plan.
She noticed we had a long layover on the return journey and was I aware? I acknowledged that I was aware of this and I planned to stay in the transit hotel.
She then mentioned that the airline will pay for the hotel.
A couple of days later we received a hotel confirmation.
I have to say - the AI girl we spoke to was really excellent. Pleasant, helpful, proactive and very thorough.
I think it's part of the standard AI service. Not sure if there's a minimum time you need to be in transit though. We land in Delhi at about 19.00 and depart the following day at around midday.