Bake window derives itself: %-knob fold, declick pad, Gate held to exhaustion, preview velocity; Hold is the one knob a loop needs

src/shell/instrument/reasampler_editor.h

@@ -99,6 +99,11 @@ private:
     // the pure deck_groups module's — this alias keeps the shell's spelling.
     using ParamControl = instrument::ui::DeckParam;
 
+    // The chrome knobs are drags of kind kDeckKnob with no place in the deck's id space, so
+    // they take negative sentinels (-2 is the preview velocity). Being outside
+    // [0, DeckParam::kCount) is what keeps liveCommitFor answering "not a live control".
+    static constexpr int kBakeHoldKnobId = -3;
+
     // The waveform markers on the waveform band: start-point + the sustain loop's two ends,
     // in draw + hit order, then the crossfade handle. The crossfade is NOT part of the
     // full-height column hit-test — it answers only in its top-strip handle (waveform_view's
@@ -127,6 +132,7 @@ private:
         kEnvRadio,        // an envelope deck's overlay-select radio (index = radio control id)
         kCurveNode,       // a velocity-curve control point (index = point index)
         kVelKnob,         // the chrome preview-velocity radial knob
+        kHoldKnob,        // the chrome bake-Hold radial knob
         kStripKey,        // a piano-strip key (index = MIDI note); carries the name tooltip
         kPopupClose,      // the curve popup's Close (x) button
     };
@@ -334,6 +340,11 @@ private:
     };
     SetupMarkers pickedMarkers(std::int64_t frames) const;
 
+    // Whether the loaded sound's bake window needs the user's Hold — the pure predicate
+    // (bake_plan.h) answered against the markers this face is showing. Decodes and reads the
+    // bank, so it is called on the sync tick, not per paint.
+    bool resolveBakeHoldNeeded();
+
     // Writes `m` into params_ as the loop/start override. Does NOT call commitAndReload —
     // callers decide live-drag vs final commit.
     void applyMarkers(const SetupMarkers& m);
@@ -378,6 +389,8 @@ private:
     double liveSampleRate() const;
     // Persisted preview velocity as a 0..1 slider value (MIDI 1..127 -> [0,1]).
     double previewVelocity01() const;
+    // The bake Hold division as a 0..1 knob position, via the pure bake_hold map.
+    double bakeHoldNorm() const;
 
     // The normalized [0,1] value a deck knob shows — parameter-set ids route through
     // controlValue/keyTrack; processor-side ids (voice count, master gain, preview velocity
@@ -430,6 +443,10 @@ private:
     // Whether the extension's bake action is registered, resolved on the same tick that
     // governs the button's paint, so the control is never enabled and then refusing.
     bool bakeAvailable_ = false;
+    // Whether the bake's window still needs the Hold control (bake_plan.h's
+    // bakeWindowNeedsHold). Resolved on the same tick as bakeAvailable_ rather than per paint:
+    // answering it costs a bridge read + bank parse whenever no loop override is set.
+    bool bakeHoldNeeded_ = false;
     std::string bakeMessage_;   // last outcome, shown in the title band
     int bakeMessageTicks_ = 0;  // sync ticks the message survives