instrument: snap live params onto a fresh voice, roll a live drag back on capture loss, serialize the seqlock's two writers

src/shell/instrument/CLAUDE.md

@@ -68,7 +68,8 @@ scattered `#ifdef`s in the VST shell, except the one described below).
   (`DEF_CLASS2` / `INLINE_UID` / `FUID` from `pluginfactory.h` + `funknown.h`).
 
 **The three commit tiers (Θ-W3).** An edit reaches the audio by exactly one of three routes, and
-which route a control takes is decided once, by the pure `isLiveDeckParam` predicate — see
+which route a control takes is decided once, by the pure `isLiveDeckParam` / `liveCommitFor` pair
+(`core/instrument/ui/deck_groups`) that the editor's `dragCommitsLive` only maps onto — see
 `core/instrument/CLAUDE.md`'s "Live parameter delivery" for the rule and its rationale.
 1. **Full reload** — `reloadInstrument`: bridge read, WAV re-decode, fresh engine, snapshot swap.
 2. **Engine rebuild** — `rebuildVoiceEngine`: same drain-slot swap around the already-decoded
@@ -76,10 +77,9 @@ which route a control takes is decided once, by the pure `isLiveDeckParam` predi
 3. **Live** — `publishLiveParams` (and `masterGain_`, the original of the shape): a lock-free
    publish the audio thread observes at block boundaries. No rebuild, no snapshot, no disk.
 
-`liveParams_` is declared ahead of the instrument slots so it outlives every snapshot pointing at
-it. The editor's `commitLive` is the tier-3 peer of `commitAndReload` and still writes the
-parameter set, so persistence is unchanged — `getState` serializes `params_`, never a reload
-artifact, and the reload was never the persistence trigger.
+The editor's `commitLive` is the tier-3 peer of `commitAndReload`; why it still writes the
+parameter set is recorded at its declaration in `reasampler_editor.h`, and why `liveParams_` is
+declared ahead of the instrument slots at that member in `reasampler_processor.h`.
 
 **Non-goals / guardrails.**
 - The instrument never captures and never inserts into the arrange. Playback is a