Locking the monthly trend formula

First fix: the net-revenue trend chart. Each time someone asks for it, the monthly numbers shift slightly, because Genie rebuilds the time-series logic from scratch every run. Leadership can't trust a chart that won't sit still.

This is a loose-formula problem, so the fix is a SQL example: the same lever you used for net revenue, now applied to a monthly time series.

Note: If your session was restarted, or you want to jump straight to the solution, open the Ch3 - Complete - Wanderbricks Sales Analytics space.