I can't prove what happened on site
Days move quickly, and the facts are being left to memory, messages and photographs with no shared order.
What's happening?
A site record works because it is made while the work, weather, deliveries, people and decisions can still be identified. Weeks later, photographs without a date or context and messages spread across phones rarely show the same clear sequence.
A short diary and dated photo log make the build easier to run as well as easier to look back on: they show what was done, what changed and what needs attention next. If keeping that record is one part of a wider need to control payments, changes and the budget, it needs an owner across the whole commercial routine.
The solution
Start a usable daily record now, and give the wider money and record routine proper control if it has outgrown your desk.
If you would rather it were done for you, Commercial Management is the service that does it.