Three separate errors, each of which quietly threw away good material.

**Where it looked.** Evenly-spaced probe windows sample the gaps. A stem is not
stationary — measured on ANGIE, even windows read HIHATS at -60.9 dBFS / 1.4%
active where the full file says -48.8 / 9.7%, and missed PAD STUFF's material
entirely (0.0% vs 6.9%) because that stem only plays in two sections. Windows are
now ranked by energy and chosen where the stem is actually playing.

**What it measured.** Usability was gated on overall RMS, which on a sparse stem
measures how much silence it contains, not whether it has material in it. ANGIE's
HIHATS stem is -48.8 dBFS RMS and a perfectly good hi-hat stem peaking at -14.7.
Level and activity now come from the whole file (it is only a frame-RMS pass) and
the gate is peak plus activity relative to the stem's own peak. Three ANGIE stems
and two MAREA stems come back from the dead.

**What it concluded.** "Mostly low energy, low centroid ⇒ bass" fires on a drum bus,
because a modern kick carries most of a drum mix's energy: ALL DRUMS reads lf 0.86,
centroid 216 Hz, indistinguishable from BASS on those features. So ALL DRUMS was
being filed into the bass kit AND mono-summed, and KICK with it. Onset density is
asked first now (ALL DRUMS 5.5/s vs BASS 1.1/s), and a `hits` claim survives a bass
measurement, because a kick IS low and slow and only the label says it is one hit.

And the authority question underneath all of it. The house rule is that a sound's
role is never INFERRED from its name; it is not that a producer's label about their
own stem is worthless. Those have very different evidential weight. Presence and
bass are decided by measurement — a stem under -40 dBFS peak has nothing in it, and
"all energy under 150 Hz, nothing above 2 kHz" is unambiguous. Everything else keeps
the label, because onset density cannot separate a rhythmic rhodes from a drum bus:
MAREA's KEYS2 reads 5.1 onsets/s and its sparse CLAP reads 1.0, so measurement alone
files both in the wrong kit, silently. Disagreements are reported, not resolved.

Also: register_fred_rights.py records a freshly cut third-party kit in the rights
ledger as third_party WITH its provenance, at the moment of cutting. Left alone it
would land as `unknown` at the next --init, which blocks correctly but blocks with
no reason attached.