probe-chain reported piment_bresilien's d10 as "DECAYING, almost certainly an
xfade tail" in two consecutive runs. It is nothing of the kind: d10 is a `mask
"<t f!7>"` riser — one cycle sounding, seven silent — and the sparkline showed it
plainly, dipping and coming back (|▇▇▇▇▇▅▃▇▇▇▆▄|). The classifier was reading
head-quartile vs tail-quartile, which is a monotonicity question answered with two
averages: exactly the missing-information mistake that made an aggregate unable to
tell a fade from a sparse part, one level up.

First attempt asked "does it recover after its lowest bin?" — which fails when the
dip lands at the END of the window, since there is no 'after' to recover into, and
that is precisely the real d10's shape. The right evidence is REPETITION: count
how many times the level crosses its own midpoint downward. **A monotonic fade
crosses once, by definition. Two or more is a cycle, and a cycle is a part.**

Validated against seven synthetic shapes before trusting it on real audio, and
they now separate cleanly: gated-riser-with-a-dip-at-the-end -> GATED/SPARSE,
spiky-sparse -> GATED/SPARSE (this one was misclassified as DECAYING even in my
own self-test and shipped that way), monotonic decay -> DECAYING, decay after a
steady head -> DECAYING, silent tail -> DIED, plus STEADY and RISING.

Why it matters more than the numbers suggest: a tool that cries wolf on a healthy
riser gets ignored on the night it is right. J-7 is the wrong week to teach PLN to
distrust the instrument.

Also lands tools/check-tracks.sh — the empirical pre-gig gate. There is no static
typechecker for a .tidal file (it is a GHCi fragment, not a module), so the only
honest question is "evaluate it and does sound come out". Three times this week a
silent rig was really a compile error, and each time the damage was TOTAL rather
than partial because a blank line is Tidal's block separator and these tracks have
almost none. All-orbits-silent is therefore diagnostic: the track did not compile.
Run it the day before a gig and after ANY BootTidal.hs edit, since a broken helper
silences the whole corpus at once. It distinguishes Tidal faults from Ardour faders
and refuses to let a mixer problem read as a track bug.