I asked Lovable only this vague question:

Build a web app that implements the GASB87 Lessee and Lessor standard for calculating leases. Take as input a lease, keep a record of all leases, calculate all schedules and disclosures and journal entries.

And it responded, with only one change request from me (switching from monthly to annual journal entries) with a fully built site with authentication, database etc.:

As a developer this would have taken me a week to get to this level of polish.