The end-to-end gate result, plus the two findings that arrived after the log was
first written: the mixer is clean LIVE (zero "Ardour eats it" across all 10 tracks,
after PLN raised the physical faders mid-session), and the rig does not xrun under
musical load — zero across 60s at maximum event density, scsynth ERR = 1 all session.

Also records the fourth instrument error, which is the best story of the day: the
xrun counter that climbed +816 in 25 seconds and looked exactly like "heavy patterns
cause dropouts on gig week" was probe-chain's own capture streams. Remove the probes,
repeat the identical musical load, get zero. Every probe run creates and destroys ~18
PipeWire nodes and each renegotiation costs Ardour an xrun.

The pattern across all four: the arithmetic was never wrong. Three of them answered a
question about SHAPE with a pair of summary statistics; the fourth measured a system
that included the measurement. What makes them dangerous is that a perturbing
instrument produces PLAUSIBLE numbers pointing at the wrong subsystem, and
confirmation bias supplies the rest — I was looking for a crackle cause and was
handed one.