fix(boot): an UNTOUCHED "^NN" yields no events, not 0 — the real mute-bomb (#55)
The bug behind "no sound on d5 in perfect.tidal, meter moves, master silent,
plays a bar then slowly fades to zero, then crackles". Also, finally, the
true root of #21 — which was diagnosed as a missing `djfbus` and fixed as
"safe at rest (0)", when the actual defect was one layer deeper.
FINDING, proven by queryArc against an empty controls map (not by ear):
gF1 $ sound "bd", knob never touched -> SILENT (no events)
gMask untouched -> SILENT
gMute3 untouched -> SILENT
gain ("^77" * 1.3) untouched -> SILENT
gPanic untouched -> SILENT
A bare `"^NN"` whose CC has never arrived does NOT default to 0 — it yields
NO EVENTS AT ALL. And `#` (i.e. `|>`) cannot emit without a value on its
right-hand side, so the entire stream disappears. Every g*-wrapped stream in
the corpus is therefore silent until that physical control is moved once.
This is why "move all the controls" was always step one of a gig, and why
PLN's rig felt fine for months: the habit was masking a mute-bomb. Today's
BootTidal restart (to pick up the 77903244 DJF fix) wiped the control map and
re-armed it across the whole surface at once — so the fix appeared to make
things worse.
It also explains the odd "plays one bar then slowly fades to zero": `dN` is
`xfade N`, which crossfades the outgoing pattern out over 4 cycles while
fading the new one in. The new one had no events, so what PLN heard was the
OLD pattern dying gracefully into nothing — meter moving throughout, master
quiet once the fade completed. The symptom looked like a filter closing;
it was a crossfade to silence.
TWO-LAYER FIX, because one layer cannot reach everything:
1. `orDef` in the helper let-block — substitutes a default when a control
pattern is empty. Applied to gDJF (0.5 = centre = true bypass),
midiOn/midiOff/midiNo/midiBoth (0/1/1/0 = "not pressed"), midiGGlobal
(0.769, so *1.3 == unity rather than 0), and gPanic (0 = normal, not
silent). It must live at the HELPER level, not per call site, because
tracks combine controls arithmetically — `midiOn ("^34" - "^18")` in
perfect.tidal:63 — and `touched - untouched` is itself empty, so a
per-CC default could never catch it.
2. Boot-time control seeding via `setF` — the corpus-wide half. `orDef`
cannot reach the 1860 sites across 343 track files that apply controls
directly (`# crushbus 41 (range 16 3.5 "^53")`). Editing those is
#46-scale work. Seeding every LCXL control at boot fixes all of them at
once while touching no track file; a real CC overwrites its seed the
instant the knob moves.
Seed policy follows the authoring convention `range <neutral> <extreme>`,
so 0 == neutral: A/B knobs 0, C1-C3 0.5 (DJF centre), C4-C8 0, fader 77
0.769 (unity), faders 78-84 1.0 (gains open = audible), all buttons 0.
Seed coverage was verified by set-difference, not assumed: 49 seeded vs 54
distinct "^NN" in live/. The 5 stragglers were each resolved rather than
waved off — ^45 needs no seed (it flows through midiOn, so orDef covers
it), ^6 and ^61 are commented out at their only call sites, and ^1 (an
external keyboard modwheel) and ^21 were added explicitly.
Verification of the fix, all four knob positions, via an explicit controls
map — untouched now bypasses and NO touched behaviour changed:
untouched -> cutoff=20000 hcutoff=20 (was: SILENT)
at 0.0 -> cutoff=180 hcutoff=20 (low-pass to subbass)
at 0.5 -> cutoff=20000 hcutoff=20 (bypass)
at 1.0 -> cutoff=20000 hcutoff=8000 (high-pass to superhigh)
gMute3 pressed -> SILENT (mute still mutes)
gPanic armed -> gain 0.0 (panic still panics)
tools/check-boot.sh gains a second pass over the seed block (pinning the
`streamSetF :: Stream -> String -> Pattern Double -> IO ()` signature it
calls through), so neither half of this can rot silently. Its own first
attempt at that pass was itself broken — a sed that produced
`_seed = _seed = concat` — and the checker caught it. Same lesson as
77903244: run the guard, don't trust that you wrote it correctly.
prelude.tidal (the stale-boot rescue sheet) carries the matching orDef form
plus a ready-to-eval `_seedNow` list, for the case where a gig laptop boots
silent and the cheapest fix is one paste rather than sweeping 40 controls.
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