Acknowledge and incent the exit plan from the beginning
Incrementally, it might make sense to hire an independent audit on occasion. This might be hiring a senior to jump into the codebase for a week or two to see if they can make sense of it or see any glaring red flags. The important part is them knowing this will take place and them not knowing exactly when or by whom.
The important part is them knowing this will take place and them not knowing exactly when or by whom.
I recommend caution with this kind of approach. Even if you're bringing in a team of freelancers instead of hiring employees trust is still an essential foundation for the relationship. Clients who play silly games tend to get fired abruptly because it creates a toxic working relationship that isn't good for anyone involved.
You should be able to have an open and ongoing conversation with your team of freelancers about the long-term intentions for the system they are building for you and they should transparently and proactively work towards your goals without being nannied. If that's not happening then you don't need some kind of surprise audit - you need to find different freelancers who are on the same wavelength as you.
Incrementally, it might make sense to hire an independent audit on occasion. This might be hiring a senior to jump into the codebase for a week or two to see if they can make sense of it or see any glaring red flags. The important part is them knowing this will take place and them not knowing exactly when or by whom.