Application projects become expensive when the team starts coding before agreeing what “working” means. Discovery is the place to make the invisible rules visible.
Ask about the work
Who uses the application? What triggers a task? What information is required? Which decisions can be automated? What happens when data is missing or wrong? Who can view, edit, approve, export, or delete it? What must be retained?
Ask about the environment
Which systems need to connect? Are there limits from an existing API? What browsers and devices matter? Who will support the application after launch? What is the smallest release that would prove value?
These answers give a web application team something more useful than a feature wishlist: a problem worth solving.