desire.tidal measured 0/9 orbits: every declared channel SILENT AT SOURCE, master
bus at -inf. Not the sample-buffer bug (b4f62757 fixed that), not a fader — the
file simply never compiled.

    off 0.125 (|+ note 12 . (|* gain 0.6))

`.` binds tighter than the section, so this parses as `|+ (note 12 . (|* gain
0.6))` — composing a function into a ValueMap. GHC's own words: "'(.)' is applied
to too few arguments". The fix is one pair of parens: `(|+ note 12) . (|* gain
0.6)`. After it, 9/9 orbits measure STEADY through SC and Ardour.

WHY IT COST A WHOLE TRACK. desire.tidal has ZERO blank lines, and a blank line is
Tidal's block separator — so the file is ONE block, and a block either compiles
entirely or not at all. One character took nine orbits. This is the third track
this week where "the rig is silent" was really "the code did not compile", and it
was only visible because the editor stopped deleting the word "error" from GHC
messages (fork commit 374d8a3): PLN read the EVAL ERROR notification off his
screen and forwarded it. Blank lines between orbits are free gig insurance.

Also lands tools/control-lens.py, the instrument for the other half of the
question. probe-chain proves an orbit makes LEVEL; it cannot prove a control
WORKS, because rms is blind to a DJ filter or a bit-crusher — those move timbre
at roughly constant loudness. So control-lens measures the right quantity per
control kind: spectral centroid + band energies for filter/crush, rms for
gain/mute, onset rate for ply/density. It drives the CC through the same path a
physical knob takes (aseqsend -> SC MIDIFunc.cc -> /ctrl -> sStateMV, reused from
lcxl-init rather than reinvented), captures before and after, and refuses to
guess: a contaminated tap is DISCARDED, a silent baseline is SKIPPED (else one
dead fader reads as twelve dead knobs), and "no measured change" is reported as
NO CHANGE, never softened to "subtle". It also hard-refuses CC 77-84, which are
MIDI-learned to Ardour's track gains.