"I'll pay half the cost, for the loft" - From Searching to Agreeing on Group Property Rentals

Rental property group booking is often a complex, asynchronous, multi-day, collaborative task that requires more than just support for search. With diverse preferences and possibly conflicting requirements, collaborative booking tools must also promote agreement. Informed by effective mediation principles, we design CREST to drive users through the stages of group booking: search, discuss and agree. Templated messages inserted by CREST-bot, a rule-driven agent that embodies one of many mediator roles, nudge users to consider certain properties, engage in conversations, negotiate better terms through house rules, and finally sign a contract to conclude the process. Through a mixed-methods user study, we evaluate how CREST's novel, mediation-inspired features lead to more satisfying outcomes over a baseline that implements state-of-the-art collaborative search features.