Reported: no activity in the master meter.
Cause: `MasterLevel` measures the buffer the ENCODER receives, and that buffer only exists while the
mix is being pulled — streaming or recording. Idle, nothing fills it, so the master read zero while
the bays below it moved. A master that is dead between sessions is a gap in the design.
Now: while a session runs the master shows the measured mix (unchanged); idle it shows an estimate
computed from the same measured sources and the same gains the mix applies
(`MeterScale.MonitorFraction`, pure + tested). Two ladders can therefore never tell contradictory
stories about whether audio exists.
Guard: MeterScaleTests pins the estimate — silence reads zero, a quiet source at unity is visible,
two sources add, and gain is applied in the LINEAR domain like the mix (scaling the display fraction
would be a different, wrong curve).
gramps
e92ce4bb63