Merge pth-w4-t2-velocity-deck-and-bipolar-curves: one VELOCITY deck, bipolar pitch and filter curves multiplying their depth knobs, and a drawn preview glyph

2026-07-31 20:27:56 -04:00
parent 4fecb58c0a 5e290119c5
commit a32ab4b5b2
42 changed files with 1245 additions and 344 deletions
@@ -243,10 +243,12 @@ anything for a trigger shape.
  reloads** via the instrument's own `ComponentState` (envelope-bumped), never via the
  extension's `persist` ext-state module (that would make it project-global rather than
  per-instance and leak an instrument concern into the extension's key space).
- **Velocity curve** — the one non-back-compat surface in S-VIEW: an
+- **Velocity curves** — three of them (amp, pitch, filter), all per-instance, edited from ONE
-  already-saved instance with no stored curve now plays every velocity at unity under the
+  deck group. The amp curve is the one non-back-compat surface in S-VIEW: an already-saved
-  flat-default (Option A), not bit-identical to the old linear `velocity/127` mapping —
+  instance with no stored curve now plays every velocity at unity under the flat-default
-  a deliberate, Daniel-approved behavior change (see `velocity_curve` in Modules).
+  (Option A), not bit-identical to the old linear `velocity/127` mapping — a deliberate,
  Daniel-approved behavior change. The pitch and filter curves are bipolar and off by default
  (see `velocity_curve` in Modules).
 ## Modules
@@ -260,13 +262,13 @@ anything for a trigger shape.
  - `voice_engine.h` / `voice_engine.cpp` — `VoiceEngine`: note routing, bounded-stealing allocation, user-parameterized voice count (1–32, default 16), `VoiceMode` Poly/Mono (last-note held-note stack, `MonoTrigger` Retrigger/Legato), two-tier panic (CC 123 = all-notes-off release, CC 120 = immediate hard-stop including Trigger one-shots), and the block render loops. Preview injects a synthetic note-on at the loaded capture's root note into the main `VoiceEngine` — no dedicated `PreviewCard`; preview obeys polyphony/mono/voice-stealing/envelopes.
 - `engine/loop/` — the sustain loop's ONE validity/clamp fold (`resolveLoop`) plus its pre-seam crossfade geometry and the editor's default handle span; see `engine/loop/CLAUDE.md`. The voice folds it once at note-on; the crossfade weight is header-inline because it rides the per-sample read.
 - `pitch_shift` — hand-rolled **correlation-aligned SOLA** (splice-overlap-add) pitch shifter for the Preserve playback mode: one active read tap chases the write head at the shift ratio; each splice jump is refined by a cross-correlation search so the new read point is waveform-aligned, then old and new taps are crossfaded (raised-cosine, amplitude-complementary). Replaces the prior dual-tap OLA whose fixed half-window tap offset caused anti-phase cancellation on many source frequencies. **GA2:** ring buffer **primed with the actual upcoming source** at note-on (was zero-filled) → gap-free frame-0 onset, ~25 ms Preserve onset latency eliminated (Preserve now speaks on frame 0, matching Varispeed), and real-content-bounded tail (last-window tail-truncation gone). No third-party dependencies; RT-discipline: no allocation in `process()`.
- `velocity_curve` — pure velocity→amp transfer curve: `VelocityCurve` evaluated by a Fritsch–Carlson monotone cubic Hermite spline (no overshoot outside [0,1]). `eval(velocity)` called once per note-on. `flat()` default (y=1, every velocity→unity) replaces the prior fixed `velocity/127` path — a deliberate non-back-compat behavior change (Daniel-approved).
+- `velocity_curve` — the pure velocity transfer curve shared by all THREE destinations: `VelocityCurve` evaluated by a Fritsch–Carlson monotone cubic Hermite spline (no overshoot). `eval(velocity)` called once per note-on. It carries its own y `CurveDomain`: UNIPOLAR [0,1] is the amp's GAIN, defaulting to `flat()` (y=1, every velocity→unity — a deliberate non-back-compat replacement of the old fixed `velocity/127` path, Daniel-approved); BIPOLAR [−1,1] is the signed modulation shape for pitch and filter, defaulting to `zero()` so velocity modulates neither until a curve is drawn. A bipolar curve does not imply the absence of a depth beside it: the filter keeps its `velAmount` knob and the two compose multiplicatively (`velAmount × curve.eval(v)`, `play_params.h`), while the pitch curve's throw is the fixed `kVelocityPitchRangeSemitones`.
 - `master_gain` — pure dB↔linear taper math (FB1): normalized [0,1] ↔ dB ↔ linear for the post-mixer master gain control (−∞…+24 dB, norm 0 = true silence, unity ≈ 0.714). Shared by the editor knob and the processor multiply so the needle, persisted value, and audio multiply cannot drift.
 ### `map/`
 - `sample_map` — the bank blob → selected capture resolve, the channel policy (downmix / dual-mono / L-R split), `InstrumentParams` (the ONE parameter set: root/loop/start overrides, keyTrack, velocity curve, `PlaySeconds`), the single override-beats-intrinsic fold (`resolveCapture`, shared by the bank and refs paths so they cannot drift), and the `SampleData` build. **Wall-clock times stored as rate-free SECONDS, resolved against the live project rate — NO hardcoded sample rates in `src/`** (Daniel's standing ruling, load-bearing). Deliberately does NOT link the voice engine: the build's product is plain `SampleData`.
- `component_state_io` (`core/instrument/map`) — the `ComponentState` envelope + params-payload binary codec (envelope v1…v11, params payload v1…v11), split out of `sample_map` (Q-W2v, T4-13 ≡ T2-07) so BOTH artifacts can link the codec without the extension pulling in the whole voice engine to serialize one preset blob — the extension's `instrument_drop` and the instrument's processor read/write the identical bytes, so the cross-artifact contract cannot drift. Payload v1…v7 are the RETIRED per-zone lists: still read, lifting by adopting zone one's capture + parameters (that first zone is what the old first-match resolve actually played, so it is also what supersedes the envelope's stored selection id). Payload v9 appends the per-voice filter tail; a v8 blob is a strict prefix of it and lifts to the off/neutral filter default. Every tail since is a strict suffix on the same discipline — v10 the staged curves, v11 the loop crossfade.
+- `component_state_io` (`core/instrument/map`) — the `ComponentState` envelope + params-payload binary codec (envelope v1…v11, params payload v1…v12), split out of `sample_map` (Q-W2v, T4-13 ≡ T2-07) so BOTH artifacts can link the codec without the extension pulling in the whole voice engine to serialize one preset blob — the extension's `instrument_drop` and the instrument's processor read/write the identical bytes, so the cross-artifact contract cannot drift. Payload v1…v7 are the RETIRED per-zone lists: still read, lifting by adopting zone one's capture + parameters (that first zone is what the old first-match resolve actually played, so it is also what supersedes the envelope's stored selection id). Payload v9 appends the per-voice filter tail; a v8 blob is a strict prefix of it and lifts to the off/neutral filter default. Every tail since is a strict suffix on the same discipline — v10 the staged curves, v11 the loop crossfade, v12 the velocity→pitch curve. v12 also RE-TAGS the y DOMAIN of one frozen slot inside the v9 filter tail — its velocity curve reads bipolar from v12 on, unipolar before — which needs no version branch, because a pre-v12 curve's y values are already valid bipolar ones; every other filter slot, `velAmount` included, keeps its meaning.
 - `params_payload` — the PARAMS-PAYLOAD half of that codec, split from the envelope half on the axis the format already has: the payload carries its own version and grows independently, so the two version ladders are two responsibilities. An INTERNAL seam — the public entry points stay `serialize`/`deserializeComponentState`. The prose ladder and every version constant stay in `component_state_io.h`, their one home.
 - `bank_sync` — generation change-detection + assignment-request consume: owns the yes/no decision logic so the rules are provable without a host. The processor shell owns cadence and side effects.
 - `bridge_marshal` — pure marshalling helper for the REAPER VST-host bridge read: interprets the `GetProjExtState` int return against its filled buffer.
@@ -276,7 +278,7 @@ anything for a trigger shape.
 - `editor_geometry` (`core/instrument/ui`) — the shared geometry VOCABULARY every instrument UI module speaks: the `core::ui::Rect` alias, `contains()`, and `OverlayArea` (a one-field `Rect` wrapper, no implicit conversion from `Rect`). Header-only (an INTERFACE CMake target), so it carries no layout of its own.
 - `sample_bands` — **THE band-stack allocator**, and the only module that owns the Sample face's vertical inventory — including `kEditorMinWidth`/`kEditorMinHeight`, the editor's client-area floor, which IS its default size (the shell's `checkSizeConstraint` and opening `ViewRect` both read it; the face grows, never shrinks below what the stack is laid out for). Three bands top-to-bottom (CHROME toolbar+control row / WAVEFORM elastic, floored at two stacked lanes / DECKS bottom-anchored at the knob deck's own wrapped height), plus the waveform band's lane split (`waveformLanes` takes a resolved `LaneSplit`, not a raw bool — only `waveformSurface` folds the source-channel-count decision in). A shared READ-ONLY surface for every band owner — a band's interior module lays out inside the rect it is handed and never re-allocates the stack.
- `sample_chrome` — the CHROME band's interior: the toolbar row (title + the whole right-anchored control run — preview, velocity knob cell, curve button, channel toggle, Browse) over the strip row, which the piano strip owns outright. The title takes what the run leaves; the strip takes its whole row, inset only by the shared band pad so it lines up with the waveform band beneath.
+- `sample_chrome` — the CHROME band's interior: the toolbar row (title + the whole right-anchored control run — preview, velocity knob cell, channel toggle, Browse) over the strip row, which the piano strip owns outright. The title takes what the run leaves; the strip takes its whole row, inset only by the shared band pad so it lines up with the waveform band beneath. Also `previewGlyph`, the preview button's play triangle — three vertices for one filled-triangle draw, so the button's label needs no font metric and no image asset.
 - `keyboard_strip` — piano-keyboard strip: true white/black key geometry (whites tiled at one width, blacks overlaid at one width and height, straddling their boundary), hit-test resolving black-over-white by zone, root-marker rect, the absolute-position drag resolver, and MIDI note naming under the C4 convention. **Same-class keys are one integer width by construction; the residue of an indivisible band width (`w % 75`, up to 74 px) lands in symmetric end margins, never in a key** — uniform widths and gap-free edge-to-edge tiling cannot both hold, and uniformity wins.
 - `waveform_view` — the WAVEFORM band's interior: `waveformSurface` resolves the drawn lane(s) (two stacked lanes, L over R, only when the mode is stereo AND the source has a second channel — a mono source under stereo mode is dual-mono and draws one lane) plus **the** overlay area, and `laneEnvelope` splits one multi-channel envelope pass per lane. Also maps frame span linearly across a rect; generic named draggable markers with drag-delta resolver, clamp, and zero-crossing snap, plus `markerHandleRect` — a top-strip grab tab distinct from a marker's full-height column, so two markers that share a frame stay independently grabbable (the column goes to the first in draw order; the tab, asked first, resolves the other).
  - **Overlay contract (consumed by later waveform work).** `WaveformSurface::overlay` — equivalently the standalone `waveformOverlayArea(band)` — is the FULL band in both modes. Everything riding the waveform (the amp-envelope trace and its node handles, the start/loop markers, the loop region) draws ONCE into it, spanning both stacked lanes; hit-testing resolves against the same area so a grab in the lower lane reaches them. Anything drawn or hit-tested per lane is a duplicate and a defect — structurally enforced: `overlay` is the distinct `OverlayArea` type (`editor_geometry`), not `Rect`, so every overlay-consuming API (`frameToX`/`markerAtPoint`/`resolveDragFrame`, `envelope_edit`'s `nodeAtPoint`/`resolveNodeDrag`, `envelope_overlay`'s `buildEnvelopePolyline`) rejects a lane rect at compile time rather than silently accepting one.
@@ -285,7 +287,7 @@ anything for a trigger shape.
 - `param_slider` — parameter control-panel: vertical stack of TOGGLE (two-segment selector) and SLIDER (horizontal track) rows; maps normalized value to/from handle pixel.
 - `embed_strip` — compact single-row control layout for embed mode in the track FX chain.
 - `knob_deck` — pure knob-deck layout + hit-test (FB1): group-box / caption-row / compact-toggle / knob-cell geometry, deterministic whole-group wrap, `DeckLayout` / `DeckHit`. Mirror of `action_bar`/`param_slider`; no LICE or REAPER types.
- `deck_groups` — also home to `isLiveDeckParam` and `liveCommitFor`, the editor's whole commit-tier routing decision (see "Live parameter delivery" above), and to `OverlayEnv` + `nextOverlaySelection`/`overlayEnvInert`, the whole overlay-selection state machine (exclusivity, the none resting state, and which selections a disabled group makes inert); WHICH groups the Sample face's deck carries, split from `knob_deck`'s HOW they lay out: the `DeckParam` control-id space (the editor's `ParamControl` is an alias of it), the `DeckGroupId` list, `sampleDeckGroups` in signal-flow order (**pitch → filter → amp**, then voice/master), and the deck's bipolar-knob law. Reads `PlayMode` for the AMP group's Gate/Trigger face, which is why this and not `knob_deck` is the module that touches the engine's value layer.
+- `deck_groups` — also home to `isLiveDeckParam` and `liveCommitFor`, the editor's whole commit-tier routing decision (see "Live parameter delivery" above), and to `OverlayEnv` + `nextOverlaySelection`/`overlayEnvInert`, the whole overlay-selection state machine (exclusivity, the none resting state, and which selections a disabled group makes inert); WHICH groups the Sample face's deck carries, split from `knob_deck`'s HOW they lay out: the `DeckParam` control-id space (the editor's `ParamControl` is an alias of it), the `DeckGroupId` list, `sampleDeckGroups` in signal-flow order (**pitch → filter → amp**, then velocity/voice/master), and the deck's bipolar-knob law. Reads `PlayMode` for the AMP group's Gate/Trigger face, which is why this and not `knob_deck` is the module that touches the engine's value layer. Also home to `CurveTarget` + `curveTargetFor` — the VELOCITY group's three cells are popup openers, not dials, and that predicate is the ONE place they are named, so paint, hit-test routing and the popup's title all agree. MASTER is reserved for post-voice-mixer concerns, which is why the curves sit in their own group immediately left of VOICE rather than there.
 - `curve_popup` — pure curve-popup geometry + dismissal test (FB1): centered sheet over the Sample face — width/height clamps, title row, Close button rect, curve-box rect, outside-sheet dismissal test. Mirror of `overflow_menu`; no LICE or REAPER types.
 - `envelope_overlay` — pure staged-envelope→polyline geometry for the Sample-view overlay (read from `envelope_overlay.h`): maps a `StageEnvelope` to a polyline inside a rect under whichever of TWO layout policies its `EnvKind` selects — an AHDSR draws a bounded param-domain schematic with its release RIGHT-ANCHORED to the canvas edge, an AHD draws 1:1 over the waveform's own time axis — plus a round mid-segment knot on every sloped stage that has a duration. Every vertex clamped in-canvas. Shares the `EnvNode`/`StageEnvelope`/`timeToX`/`levelToY` vocabulary with `envelope_edit` so the drawn handle and its grab region agree pixel-for-pixel. No VST3/REAPER/LICE types at the boundary.
 - `envelope_edit` — pure node hit-test + pixel-delta→clamped-param inverse map for the draggable envelope nodes and their curve knots (read from `envelope_edit.h`): `nodeAtPoint` resolves a grab to the nearest node within a pick radius (Chebyshev distance, draw-order tie-break, knots appended last so a coincident endpoint handle wins); `resolveNodeDrag` maps a pixel delta since grab to a new `StageEnvelope` under the same caller-supplied per-param clamp bounds the knobs use — a drag can never produce a param a knob couldn't. Mirror of `card_drag`/`waveform_view`; the inverse of `envelope_overlay`'s params→polyline forward map, so node-drag, knot-drag and knob-edit read/write one shared model and can never diverge.
@@ -9,6 +9,7 @@ LiveValues foldLive(const PlayParams& params) {
    LiveValues v;
    v.filterSettings = params.filter.settings;
    v.filterModAmount = params.filter.modAmount;
    v.filterVelAmount = params.filter.velAmount;
    v.filterKeyTrack = params.filter.keyTrack;
    v.filterEnv = params.filter.env;
    v.filterAhd = params.filter.trigEnv;
@@ -34,6 +34,10 @@ inline constexpr double kLiveRampSeconds = 0.020;
 struct LiveValues {
    filter::FilterSettings filterSettings{};
    double       filterModAmount = 0.0;
    // The DEPTH scaling the velocity curve, not the curve's value: the note's velocity is
    // latched, its depth is a control, exactly as filterKeyTrack is a control over a latched
    // note number.
    double       filterVelAmount = 0.0;
    double       filterKeyTrack = 0.0;
    AdsrParams   filterEnv{};
    AhdParams    filterAhd{};
@@ -116,25 +116,28 @@ struct FilterParams {
    bool enabled = false;
    instrument::engine::filter::FilterSettings settings;
    double modAmount = 0.0;   // bipolar [-1,+1], envelope -> cutoff
-    double velAmount = 0.0;   // bipolar [-1,+1], velocity -> cutoff
+    double velAmount = 0.0;   // bipolar [-1,+1], scales velocityCurve's output
    double keyTrack  = 0.0;   // octaves of cutoff per octave of (note - root)
    // The filter envelope takes the same shape the amp does under the active play mode:
    // AHDSR in Gate, AHD in Trigger. Both are stored, so a mode flip cannot lose either
    // mode's dialled values (see core/instrument/CLAUDE.md).
    AdsrParams env;           // Gate: the same staged AHDSR the amp runs; frames
    AhdParams  trigEnv;       // Trigger: the same staged AHD the amp runs; frames
-    // Shapes velocity before velAmount scales it. Linear rather than the amp's flat() default
+    // Velocity -> cutoff, in the normalized cutoff domain. The contribution is
-    // because a flat curve under a depth control would make every velocity the same offset;
+    // velAmount * velocityCurve.eval(velocity): the BIPOLAR curve carries the shape (and its
-    // the no-op at rest is velAmount == 0, not the curve. NOTE: this default only governs a
+    // own sign), the depth knob scales it, and BOTH apply. The curve is flat at 0 by default,
-    // FRESH FilterParams — the shared codec's corrupt/truncated-point-list repair
+    // so no depth setting produces velocity modulation until a curve is drawn.
-    // (VelocityCurve::fromPoints, used for both this curve and the amp's) still degrades to
+    VelocityCurve velocityCurve = VelocityCurve::zero();
    // flat() regardless, since that repair has no curve-specific fallback.
    VelocityCurve velocityCurve = VelocityCurve::linear();
 };
 // Full-scale of the velocity->pitch curve: y = +/-1 transposes by this many semitones. Shared
 // with the pitch envelope's own depth throw so the two pitch modulators speak one range.
 inline constexpr double kVelocityPitchRangeSemitones = 24.0;
 // Bundle a voice reads at start(). Defaults reproduce the bare engine (Gate, hold-0 AHDSR,
-// Varispeed, pitch envelope off, filter off) — core regression tests rely on this; the
+// Varispeed, pitch envelope off, filter off, no velocity->pitch) — core regression tests rely
-// Preserve product default is layered on at (de)serialization, see kDefaultPitchEngine.
+// on this; the Preserve product default is layered on at (de)serialization, see
 // kDefaultPitchEngine.
 struct PlayParams {
    PlayMode       playMode = PlayMode::Gate;
    AdsrParams     adsr;      // Gate amp
@@ -142,6 +145,10 @@ struct PlayParams {
    AhdParams      trigAhd;   // Trigger amp
    PitchEngine    pitchEngine = PitchEngine::Varispeed;
    PitchEnvParams pitchEnv;
    // Velocity -> pitch offset, scaled by kVelocityPitchRangeSemitones. Bipolar and flat at 0
    // by default, so it transposes nothing until a curve is drawn. Folded into the voice's
    // baseRatio_ at note-on — it is fixed for the note's lifetime, so it costs no per-frame work.
    VelocityCurve  pitchVelocityCurve = VelocityCurve::zero();
    FilterParams   filter;
 };
@@ -11,19 +11,19 @@ namespace reasampler::instrument::engine {
 namespace {
 double clampVelocity(double v) { return std::clamp(v, kVelMin, kVelMax); }
-double clampAmp(double a) { return std::clamp(a, kAmpMin, kAmpMax); }
+double clampValue(double a, CurveDomain d) { return std::clamp(a, curveYMin(d), kCurveYMax); }
-// X spans the width for [0,127]; Y spans (height-1) rows for amp [0,1] with amp 1 at the TOP
+// X spans the width for [0,127]; Y spans (height-1) rows for the domain's range with its max at
-// (pixel y increases downward, so this axis is inverted relative to amp).
+// the TOP (pixel y increases downward, so this axis is inverted relative to the value).
 double velPerPixel(const VelocityCurve::Box& box) {
    const int w = std::max(0, box.width);
    if (w <= 0) return 0.0;
    return (kVelMax - kVelMin) / static_cast<double>(w);
 }
-double ampPerPixel(const VelocityCurve::Box& box) {
+double valuePerPixel(const VelocityCurve::Box& box, CurveDomain d) {
    const int h = std::max(0, box.height);
    if (h <= 1) return 0.0;
-    return (kAmpMax - kAmpMin) / static_cast<double>(h - 1);
+    return (kCurveYMax - curveYMin(d)) / static_cast<double>(h - 1);
 }
 int velToX(const VelocityCurve::Box& box, double velocity) {
    const int w = std::max(0, box.width);
@@ -31,10 +31,11 @@ int velToX(const VelocityCurve::Box& box, double velocity) {
    const double frac = (clampVelocity(velocity) - kVelMin) / (kVelMax - kVelMin);
    return box.left + static_cast<int>(frac * static_cast<double>(w) + 0.5);
 }
-int ampToY(const VelocityCurve::Box& box, double amp) {
+int valueToY(const VelocityCurve::Box& box, double value, CurveDomain d) {
    const int h = std::max(0, box.height);
    if (h <= 1) return box.top;
-    const double frac = (clampAmp(amp) - kAmpMin) / (kAmpMax - kAmpMin);
+    const double lo = curveYMin(d);
    const double frac = (clampValue(value, d) - lo) / (kCurveYMax - lo);
    return box.top + static_cast<int>((1.0 - frac) * static_cast<double>(h - 1) + 0.5);
 }
@@ -42,39 +43,51 @@ int ampToY(const VelocityCurve::Box& box, double amp) {
 VelocityCurve VelocityCurve::flat() {
    VelocityCurve c;
-    c.points_ = {{kVelMin, kAmpMax}, {kVelMax, kAmpMax}};
+    const double n = curveNeutral(CurveDomain::Unipolar);
    c.points_ = {{kVelMin, n}, {kVelMax, n}};
    return c;
 }
 VelocityCurve VelocityCurve::linear() {
    VelocityCurve c;
-    c.points_ = {{kVelMin, kAmpMin}, {kVelMax, kAmpMax}};
+    c.points_ = {{kVelMin, 0.0}, {kVelMax, kCurveYMax}};
    return c;
 }
-VelocityCurve VelocityCurve::fromPoints(std::vector<VelocityPoint> pts) {
+VelocityCurve VelocityCurve::zero() {
    VelocityCurve c;
    c.domain_ = CurveDomain::Bipolar;
    const double n = curveNeutral(CurveDomain::Bipolar);
    c.points_ = {{kVelMin, n}, {kVelMax, n}};
    return c;
 }
 VelocityCurve VelocityCurve::fromPoints(std::vector<VelocityPoint> pts, CurveDomain domain) {
    // Stable sort so coincident-X points keep their wire order (eval stays well-defined for
    // duplicate-X knots).
    for (VelocityPoint& p : pts) {
        p.velocity = clampVelocity(p.velocity);
-        p.amp = clampAmp(p.amp);
+        p.value = clampValue(p.value, domain);
    }
    std::stable_sort(pts.begin(), pts.end(),
                     [](const VelocityPoint& a, const VelocityPoint& b) {
                         return a.velocity < b.velocity;
                     });
-    if (pts.size() < 2) return flat();
+    if (pts.size() < 2) {
        return domain == CurveDomain::Bipolar ? zero() : flat();
    }
    if (pts.front().velocity > kVelMin) {
-        pts.insert(pts.begin(), VelocityPoint{kVelMin, pts.front().amp});
+        pts.insert(pts.begin(), VelocityPoint{kVelMin, pts.front().value});
    } else {
        pts.front().velocity = kVelMin;
    }
    if (pts.back().velocity < kVelMax) {
-        pts.push_back(VelocityPoint{kVelMax, pts.back().amp});
+        pts.push_back(VelocityPoint{kVelMax, pts.back().value});
    } else {
        pts.back().velocity = kVelMax;
    }
    VelocityCurve c;
    c.domain_ = domain;
    c.points_ = std::move(pts);
    return c;
 }
@@ -84,7 +97,7 @@ namespace {
 // Fritsch-Carlson monotone-cubic tangent: a sign change (or flat) neighbour is a local extremum,
 // so the tangent pins to 0 to avoid overshoot; otherwise the weighted-harmonic-mean tangent,
 // which for collinear knots (dPrev==dNext) reduces exactly to the shared secant — this is what
-// makes the spline reproduce a straight line to ~1e-15 for linear()-style input.
+// makes the spline reproduce a straight line for linear()-style input.
 double fritschCarlsonTangent(double dPrev, double dNext, double spanPrev, double spanNext) {
    if (dPrev * dNext <= 0.0) return 0.0;
    const double w1 = 2.0 * spanNext + spanPrev;
@@ -95,29 +108,29 @@ double fritschCarlsonTangent(double dPrev, double dNext, double spanPrev, double
 }  // namespace
 double VelocityCurve::eval(double velocity) const {
-    if (points_.empty()) return kAmpMax;
+    if (points_.empty()) return curveNeutral(domain_);
-    if (points_.size() == 1) return clampAmp(points_[0].amp);
+    if (points_.size() == 1) return clampValue(points_[0].value, domain_);
    const double v = clampVelocity(velocity);
-    if (v <= points_.front().velocity) return clampAmp(points_.front().amp);
+    if (v <= points_.front().velocity) return clampValue(points_.front().value, domain_);
-    if (v >= points_.back().velocity) return clampAmp(points_.back().amp);
+    if (v >= points_.back().velocity) return clampValue(points_.back().value, domain_);
    for (std::size_t i = 0; i + 1 < points_.size(); ++i) {
        const VelocityPoint& a = points_[i];
        const VelocityPoint& b = points_[i + 1];
        if (v >= a.velocity && v <= b.velocity) {
            const double span = b.velocity - a.velocity;
            // Coincident-X neighbours (a step): zero-width segment, no interior to blend.
-            if (span <= 0.0) return clampAmp(b.amp);
+            if (span <= 0.0) return clampValue(b.value, domain_);
-            // Monotone cubic Hermite (Fritsch-Carlson): provably stays within [a.amp, b.amp]
+            // Monotone cubic Hermite (Fritsch-Carlson): provably stays within [a.value, b.value]
            // between the two knots (no overshoot), reproducing a straight line for collinear input.
-            const double d = (b.amp - a.amp) / span;
+            const double d = (b.value - a.value) / span;
            double mA = d;
            if (i > 0) {
                const VelocityPoint& prev = points_[i - 1];
                const double spanPrev = a.velocity - prev.velocity;
                if (spanPrev > 0.0) {
-                    const double dPrev = (a.amp - prev.amp) / spanPrev;
+                    const double dPrev = (a.value - prev.value) / spanPrev;
                    mA = fritschCarlsonTangent(dPrev, d, spanPrev, span);
                } else {
                    mA = 0.0;
@@ -128,7 +141,7 @@ double VelocityCurve::eval(double velocity) const {
                const VelocityPoint& next = points_[i + 2];
                const double spanNext = next.velocity - b.velocity;
                if (spanNext > 0.0) {
-                    const double dNext = (next.amp - b.amp) / spanNext;
+                    const double dNext = (next.value - b.value) / spanNext;
                    mB = fritschCarlsonTangent(d, dNext, span, spanNext);
                } else {
                    mB = 0.0;
@@ -142,15 +155,15 @@ double VelocityCurve::eval(double velocity) const {
            const double h10 = t3 - 2.0 * t2 + t;
            const double h01 = -2.0 * t3 + 3.0 * t2;
            const double h11 = t3 - t2;
-            const double y = h00 * a.amp + h10 * span * mA + h01 * b.amp + h11 * span * mB;
+            const double y = h00 * a.value + h10 * span * mA + h01 * b.value + h11 * span * mB;
-            return clampAmp(y);
+            return clampValue(y, domain_);
        }
    }
-    return clampAmp(points_.back().amp);  // unreachable (v is between the endpoints)
+    return clampValue(points_.back().value, domain_);  // unreachable (v is between the endpoints)
 }
-std::size_t VelocityCurve::addPoint(double velocity, double amp) {
+std::size_t VelocityCurve::addPoint(double velocity, double value) {
-    const VelocityPoint p{clampVelocity(velocity), clampAmp(amp)};
+    const VelocityPoint p{clampVelocity(velocity), clampValue(value, domain_)};
    // First index strictly greater, so a duplicate-X point lands immediately after the existing one.
    std::size_t i = 0;
    while (i < points_.size() && points_[i].velocity <= p.velocity) ++i;
@@ -158,12 +171,12 @@ std::size_t VelocityCurve::addPoint(double velocity, double amp) {
    return i;
 }
-VelocityPoint VelocityCurve::movePoint(std::size_t index, double velocity, double amp) {
+VelocityPoint VelocityCurve::movePoint(std::size_t index, double velocity, double value) {
    if (index >= points_.size()) return VelocityPoint{};  // no-op (out of range)
    const bool isFirst = (index == 0);
    const bool isLast  = (index + 1 == points_.size());
-    double newAmp = clampAmp(amp);
+    double newValue = clampValue(value, domain_);
    double newVel;
    if (isFirst) {
        newVel = kVelMin;
@@ -174,7 +187,7 @@ VelocityPoint VelocityCurve::movePoint(std::size_t index, double velocity, doubl
        const double hi = points_[index + 1].velocity;
        newVel = std::clamp(clampVelocity(velocity), lo, hi);
    }
-    points_[index] = VelocityPoint{newVel, newAmp};
+    points_[index] = VelocityPoint{newVel, newValue};
    return points_[index];
 }
@@ -185,12 +198,13 @@ bool VelocityCurve::deletePoint(std::size_t index) {
    return true;
 }
-VelocityCurve::CurvePixel VelocityCurve::pixelFromPoint(const Box& box, const VelocityPoint& p) {
+VelocityCurve::CurvePixel VelocityCurve::pixelFromPoint(const Box& box,
-    return CurvePixel{velToX(box, p.velocity), ampToY(box, p.amp)};
+                                                       const VelocityPoint& p) const {
    return CurvePixel{velToX(box, p.velocity), valueToY(box, p.value, domain_)};
 }
-VelocityPoint VelocityCurve::pointFromPixel(const Box& box, int x, int y) {
+VelocityPoint VelocityCurve::pointFromPixel(const Box& box, int x, int y) const {
-    // Exact inverse of velToX/ampToY (within one pixel); degenerate dims collapse the same way.
+    // Exact inverse of velToX/valueToY (within one pixel); degenerate dims collapse the same way.
    VelocityPoint p;
    const int w = std::max(0, box.width);
    const int h = std::max(0, box.height);
@@ -198,17 +212,19 @@ VelocityPoint VelocityCurve::pointFromPixel(const Box& box, int x, int y) {
        ? kVelMin
        : clampVelocity(kVelMin + static_cast<double>(x - box.left) / static_cast<double>(w) *
                                      (kVelMax - kVelMin));
-    p.amp = (h <= 1)
+    const double lo = curveYMin(domain_);
-        ? kAmpMax
+    p.value = (h <= 1)
-        : clampAmp(kAmpMax - static_cast<double>(y - box.top) / static_cast<double>(h - 1) *
+        ? kCurveYMax
-                                 (kAmpMax - kAmpMin));
+        : clampValue(kCurveYMax - static_cast<double>(y - box.top) / static_cast<double>(h - 1) *
                                      (kCurveYMax - lo),
                     domain_);
    return p;
 }
 int VelocityCurve::pointAtPixel(const Box& box, int x, int y) const {
    for (std::size_t i = 0; i < points_.size(); ++i) {
        const int px = velToX(box, points_[i].velocity);
-        const int py = ampToY(box, points_[i].amp);
+        const int py = valueToY(box, points_[i].value, domain_);
        if (std::abs(x - px) <= kCurveNodeGrabRadius && std::abs(y - py) <= kCurveNodeGrabRadius) {
            return static_cast<int>(i);
        }
@@ -221,22 +237,24 @@ VelocityCurve VelocityCurve::resolvePointDrag(const VelocityCurve& grabCurve, st
    VelocityCurve out = grabCurve;
    if (index >= out.points_.size()) return out;  // out of range -> no motion
    const double velPerPx = velPerPixel(box);
-    const double ampPerPx = ampPerPixel(box);
+    const double valPerPx = valuePerPixel(box, grabCurve.domain_);
-    if (velPerPx <= 0.0 || ampPerPx <= 0.0) return out;  // degenerate box -> no motion
+    if (velPerPx <= 0.0 || valPerPx <= 0.0) return out;  // degenerate box -> no motion
    const VelocityPoint& grab = grabCurve.points_[index];
    const double newVel = grab.velocity + static_cast<double>(dxPixels) * velPerPx;
-    // Y increases downward but amp increases upward, so a downward drag (positive dy) LOWERS amp.
+    // Y increases downward but the value increases upward, so a downward drag (positive dy)
-    const double newAmp = grab.amp - static_cast<double>(dyPixels) * ampPerPx;
+    // LOWERS the value.
-    out.movePoint(index, newVel, newAmp);  // applies box + neighbour-X + endpoint-pin clamps
+    const double newValue = grab.value - static_cast<double>(dyPixels) * valPerPx;
    out.movePoint(index, newVel, newValue);  // applies box + neighbour-X + endpoint-pin clamps
    return out;
 }
 bool VelocityCurve::equals(const VelocityCurve& other, double eps) const {
    if (domain_ != other.domain_) return false;
    if (points_.size() != other.points_.size()) return false;
    for (std::size_t i = 0; i < points_.size(); ++i) {
        if (std::fabs(points_[i].velocity - other.points_[i].velocity) > eps) return false;
-        if (std::fabs(points_[i].amp - other.points_[i].amp) > eps) return false;
+        if (std::fabs(points_[i].value - other.points_[i].value) > eps) return false;
    }
    return true;
 }
@@ -1,7 +1,8 @@
-// velocity_curve.h — velocity->amp transfer curve. eval(velocity) is called once per note-on
+// velocity_curve.h — the velocity->modulation transfer curve, shared by all three
-// in Voice::start(), never per frame. Editor hit-test/inverse-map take an explicit pixel Box
+// destinations (amp gain, pitch offset, filter cutoff offset). eval(velocity) is called once
-// rather than a Rect: this module sits below sampler_core in the link graph and must not gain
+// per note-on in Voice::start(), never per frame. Editor hit-test/inverse-map take an explicit
-// a transitive dependency on editor-layout types.
+// pixel Box rather than a Rect: this module sits below sampler_core in the link graph and must
 // not gain a transitive dependency on editor-layout types.
 #pragma once
@@ -10,17 +11,31 @@
 namespace reasampler::instrument::engine {
-// The MIDI velocity domain [0,127] and the amp range [0,1] — the box every point clamps into.
+// The MIDI velocity domain [0,127] — the X span every point clamps into.
 inline constexpr double kVelMin = 0.0;
 inline constexpr double kVelMax = 127.0;
-inline constexpr double kAmpMin = 0.0;
+inline constexpr double kCurveYMax = 1.0;
-inline constexpr double kAmpMax = 1.0;
+
 // The curve's Y range. UNIPOLAR [0,1] is a GAIN — the amp's domain, where the do-nothing
 // curve is flat at 1. BIPOLAR [-1,1] is a SIGNED modulation shape — the pitch and filter
 // domains, where the do-nothing curve is flat at 0 and the sign picks the direction. A
 // bipolar curve does not preclude a depth control beside it: the filter has one, and the two
 // compose multiplicatively (play_params.h).
 enum class CurveDomain { Unipolar, Bipolar };
 constexpr double curveYMin(CurveDomain d) { return d == CurveDomain::Bipolar ? -1.0 : 0.0; }
 // The value that changes nothing in each domain — unity gain, or zero modulation. THE one home
 // for that value: eval()'s own empty-curve fallback reads it directly, and flat()/zero() (what
 // fromPoints' sub-2-point fallback constructs) are built from it too, so a corrupt blob always
 // loses the shaping rather than inventing one, however the fallback is reached.
 constexpr double curveNeutral(CurveDomain d) { return d == CurveDomain::Bipolar ? 0.0 : 1.0; }
 // A raw-constructed point is NOT auto-clamped (the mutators own that invariant) — build curves
 // through the named constructors / addPoint rather than pushing raw points.
 struct VelocityPoint {
    double velocity = 0.0;   // X, [0,127]
-    double amp      = 0.0;   // Y, [0,1]
+    double value    = 0.0;   // Y, in the owning curve's domain
 };
 // Pick radius (px) around a node's drawn point for the editor hit-test.
@@ -28,44 +43,49 @@ inline constexpr int kCurveNodeGrabRadius = 6;
 // An X-ordered list of control points spanning [0,127], evaluated by a monotone cubic Hermite
 // spline (Fritsch-Carlson slope limiting) — a genuine curve, not a polyline, that provably never
-// overshoots a segment's amp range. For collinear knots the tangents reduce to the secant slope,
+// overshoots a segment's value range. For collinear knots the tangents reduce to the secant
-// so the spline reproduces linear()'s straight line to within ~1e-15. The two endpoints (velocity
+// slope, so the spline reproduces linear()'s straight line to within ~1e-15. The two endpoints
-// 0 and 127) are load-bearing: they keep eval total over the domain and are never deletable.
+// (velocity 0 and 127) are load-bearing: they keep eval total over the domain and are never
 // deletable.
 class VelocityCurve {
 public:
-    // flat() (endpoints (0,1)/(127,1), every velocity -> unity) is the default — see
+    // flat() (endpoints (0,1)/(127,1), every velocity -> unity) is the unipolar default — see
    // velocity_curve in the directory CLAUDE.md for why this isn't bit-identical to the
    // pre-existing linear() response.
    static VelocityCurve flat();
    static VelocityCurve linear();
    // The bipolar default: flat at 0, so velocity modulates nothing until a curve is drawn.
    static VelocityCurve zero();
    // Rebuilds from a deserialized point list, repairing the invariant defensively: box-clamps
-    // each point, stable-sorts by velocity, forces both endpoints present (synthesized if
+    // each point into `domain`, stable-sorts by velocity, forces both endpoints present
-    // missing), falls back to flat() if fewer than 2 usable points remain. A corrupt/truncated
+    // (synthesized if missing), falls back to the domain's neutral curve if fewer than 2 usable
-    // blob yields a well-formed curve, never an invariant-violating one.
+    // points remain. A corrupt/truncated blob yields a well-formed curve, never an
-    static VelocityCurve fromPoints(std::vector<VelocityPoint> pts);
+    // invariant-violating one.
    static VelocityCurve fromPoints(std::vector<VelocityPoint> pts, CurveDomain domain);
    CurveDomain domain() const { return domain_; }
    const std::vector<VelocityPoint>& points() const { return points_; }
    std::size_t size() const { return points_.size(); }
-    // Degenerate cases (shouldn't occur post-construction): empty curve returns kAmpMax; a
+    // Degenerate cases (shouldn't occur post-construction): empty curve returns the domain's
-    // one-point curve returns that point's amp.
+    // neutral; a one-point curve returns that point's value.
    double eval(double velocity) const;
    // Inserted at a velocity duplicating an existing point lands immediately after it, so a
    // subsequent move can separate them. Returns the inserted index.
-    std::size_t addPoint(double velocity, double amp);
+    std::size_t addPoint(double velocity, double value);
    // Box-clamped and X-clamped between immediate neighbours (monotonic-X grammar). The two
-    // endpoints are pinned in X (only their amp moves); out-of-range index is a no-op.
+    // endpoints are pinned in X (only their value moves); out-of-range index is a no-op.
-    VelocityPoint movePoint(std::size_t index, double velocity, double amp);
+    VelocityPoint movePoint(std::size_t index, double velocity, double value);
    // Endpoints (index 0 and last) are not deletable; that or an out-of-range index is a no-op
    // returning false.
    bool deletePoint(std::size_t index);
-    // The drawn box, in pixels: X = velocity across the width, Y = amp UP the height (amp 1 at
+    // The drawn box, in pixels: X = velocity across the width, Y = value UP the height (the
-    // top). Passed explicitly rather than a Rect — see header preamble.
+    // domain's max at top). Passed explicitly rather than a Rect — see header preamble.
    struct Box {
        int left = 0;
        int top = 0;
@@ -82,14 +102,15 @@ public:
        int x = 0;
        int y = 0;
    };
-    static CurvePixel pixelFromPoint(const Box& box, const VelocityPoint& p);
+    CurvePixel pixelFromPoint(const Box& box, const VelocityPoint& p) const;
-    // Exact inverse of pixelFromPoint (within the one-pixel quantum) — where an empty-space click
+    // Exact inverse of pixelFromPoint (within the one-pixel quantum) — where an empty-space
-    // lands as a new point. Degenerate box: zero-width reads velocity 0; height <= 1 reads amp 1.
+    // click lands as a new point. Degenerate box: zero-width reads velocity 0; height <= 1
-    static VelocityPoint pointFromPixel(const Box& box, int x, int y);
+    // reads the domain's max (the top row is what a collapsed box draws).
    VelocityPoint pointFromPixel(const Box& box, int x, int y) const;
    // `grabCurve` is the curve as of mouse-down (shell snapshots it so the delta is absolute).
-    // Maps the pixel delta to velocity/amp over the box, then applies movePoint's clamp. Zero
+    // Maps the pixel delta to velocity/value over the box, then applies movePoint's clamp. Zero
    // width/height box or out-of-range index returns grabCurve unchanged.
    static VelocityCurve resolvePointDrag(const VelocityCurve& grabCurve, std::size_t index,
                                          const Box& box, int dxPixels, int dyPixels);
@@ -97,9 +118,16 @@ public:
    bool equals(const VelocityCurve& other, double eps = 1e-9) const;
 private:
    // Private: an implicit-default curve is empty (no endpoints) and Unipolar, so a stray
    // default-construction wouldn't fail loudly — it would eval() to unity gain everywhere,
    // or a full +/-1 (a full-scale transpose / wide-open filter) if ever read as bipolar. Build
    // through flat()/linear()/zero()/fromPoints(), all of which establish the endpoint invariant.
    VelocityCurve() = default;
    // Always X-ordered with an endpoint at 0 and 127; constructors + deserialize establish the
    // invariant, mutators preserve it.
    std::vector<VelocityPoint> points_;
    CurveDomain domain_ = CurveDomain::Unipolar;
 };
 }  // namespace reasampler::instrument::engine
@@ -49,12 +49,14 @@ void Voice::start(int note, int velocity, const SampleData& sample, bool declick
    // Velocity->amp mapped once at note-on; the per-frame render just multiplies the cached
    // velocityGain_.
    velocityGain_ = sample.velocityCurve.eval(static_cast<double>(velocity));
    // Feeds both engines through baseRatio_ (Varispeed read-rate bias and Preserve shift
    // amount both derive from it below).
    baseRatio_ = keyTrackedRatio(note, sample.rootNote, sample.keyTrack);
    sample_ = &sample;
    const PlayParams& p = sample.play;
    // Velocity->pitch is fixed for the note's lifetime, so it folds into baseRatio_ here rather
    // than costing a per-frame multiply. Feeds both engines through baseRatio_ (Varispeed
    // read-rate bias and Preserve shift amount both derive from it below).
    velPitchRatio_ = velocityPitchRatio(p.pitchVelocityCurve, velocity);
    baseRatio_ = keyTrackedRatio(note, sample.rootNote, sample.keyTrack) * velPitchRatio_;
    playMode_ = p.playMode;
    pitchEngine_ = p.pitchEngine;
@@ -129,8 +131,8 @@ void Voice::start(int note, int velocity, const SampleData& sample, bool declick
        filterCutoffNorm_ = static_cast<double>(p.filter.settings.cutoffNorm);
        filterModAmount_ = p.filter.modAmount;
        filterKeyTrack_ = p.filter.keyTrack;
-        filterVelOffset_ =
+        filterVelCurve_ = p.filter.velocityCurve.eval(static_cast<double>(velocity));
-            p.filter.velAmount * p.filter.velocityCurve.eval(static_cast<double>(velocity));
+        filterVelOffset_ = p.filter.velAmount * filterVelCurve_;
        filterRate_ = static_cast<double>(sample.sampleRate);
        rModAmount_.set(p.filter.modAmount);
        rResonance_.set(static_cast<double>(p.filter.settings.resonanceNorm));
@@ -247,6 +249,9 @@ void Voice::applyLive(const instrument::engine::LiveValues& live, bool snap) {
    }
    filterCutoffNorm_ = static_cast<double>(live.filterSettings.cutoffNorm);
    filterKeyTrack_ = live.filterKeyTrack;
    // The note's curve value stays latched; only the depth over it is live. Both this and the
    // key-track depth land in the base cutoff, so they glide through rBaseCutoff_ below.
    filterVelOffset_ = live.filterVelAmount * filterVelCurve_;
    filterSettings_.morphLaw = live.filterSettings.morphLaw;
    const double baseTarget = filterCutoffBaseTarget(note_);
    if (snap) {
@@ -281,7 +286,9 @@ void Voice::retune(int note) {
    // Changes baseRatio_ without re-converting pitchEnv_'s already-configured span (the
    // baseRatio_ division in the note-on setup above), so a slide leaves that envelope on the
    // first note's domain — consistent with "touch nothing else," but the drift lives here.
-    baseRatio_ = keyTrackedRatio(note, sample_->rootNote, sample_->keyTrack);
+    // The velocity->pitch factor rides through the slide unchanged, matching velocityGain_ —
    // one gesture, one strike.
    baseRatio_ = keyTrackedRatio(note, sample_->rootNote, sample_->keyTrack) * velPitchRatio_;
    // Filter key-tracking follows the pitch: it is a function of the note, so a slide moves it
    // too. The velocity offset deliberately stays the first note's, matching velocityGain_.
    if (filterOn_) updateFilterCutoffBase(note);
@@ -48,6 +48,14 @@ inline double keyTrackedRatio(int note, int rootNote, double keyTrack) {
    return std::pow(2.0, semis / 12.0);
 }
 // 2^(curve(velocity) * kVelocityPitchRangeSemitones / 12): the velocity->pitch transpose, which
 // the voice folds into baseRatio_ once at note-on. A curve flat at 0 — the default — yields
 // EXACTLY 1.0 at every velocity and skips the pow, so an undrawn curve transposes nothing.
 inline double velocityPitchRatio(const VelocityCurve& curve, int velocity) {
    const double semis = curve.eval(static_cast<double>(velocity)) * kVelocityPitchRangeSemitones;
    return (semis == 0.0) ? 1.0 : std::pow(2.0, semis / 12.0);
 }
 // One octave expressed in the cutoff control's normalized domain, read out of the filter
 // module's OWN inverse rather than re-derived from its endpoints — the log law belongs to
 // filter_params, and a second copy here could drift from it. Evaluated at note-on only.
@@ -561,7 +569,8 @@ private:
    bool releasing_ = false;
    int note_ = 0;
    double velocityGain_ = 1.0;
-    double baseRatio_ = 1.0;     // 2^((note-root)/12): the un-modulated repitch ratio
+    double baseRatio_ = 1.0;     // key-tracked repitch ratio, with velocity->pitch folded in
    double velPitchRatio_ = 1.0; // the velocity->pitch factor alone; retune re-applies it
    double ratio_ = 1.0;         // fractional source frames advanced per output frame (this frame)
    double readPos_ = 0.0;       // fractional frame index into the sample
    const SampleData* sample_ = nullptr;
@@ -593,7 +602,10 @@ private:
    double filterRate_ = 0.0;
    double filterCutoffNorm_ = 1.0;
    double filterModAmount_ = 0.0;
-    double filterVelOffset_ = 0.0;   // velAmount * velocityCurve.eval(velocity), fixed per note
+    // The curve's value at THIS note's velocity — a fact about the note, latched at note-on —
    // and the product with the live depth, which a live depth move recomputes.
    double filterVelCurve_ = 0.0;
    double filterVelOffset_ = 0.0;
    double filterKeyTrack_ = 0.0;
    instrument::engine::filter::FilterSettings filterSettings_{};  // the note's tone controls
    float filterBaseCutoff_ = 1.0f;    // cutoff before the envelope, clamped
@@ -8,7 +8,7 @@
 // own links are velocity_curve + master_gain (wire value validation), never the engine.
 //
 // EVERY wire format below is FROZEN; the full version ladders (envelope v1..v11, params
-// payload v1..v11) must be preserved exactly. This header is the ONE home for both ladders
+// payload v1..v12) must be preserved exactly. This header is the ONE home for both ladders
 // and every version constant; the payload half is IMPLEMENTED in params_payload.
 #include <cstdint>
@@ -85,9 +85,24 @@ namespace reasampler::instrument::map {
 // AHDSR's attack/decay/release curve exponents; the filter's Trigger AHD (same five fields as
 // the amp's). A v9-or-older blob is a strict prefix and lifts to the neutral exponent 1.0.
 //
-// v11 (CURRENT WRITE FORMAT) is v10 PLUS one 8-byte LE int64: the loop crossfade in SOURCE
+// v11 is v10 PLUS one 8-byte LE int64: the loop crossfade in SOURCE frames (a source-timeline
-// frames (a source-timeline quantity like the loop points, so no rate resolves it). A v10-or-
+// quantity like the loop points, so no rate resolves it). A v10-or-older blob is a strict
-// older blob is a strict prefix and lifts to 0 — the hard seam it always played.
+// prefix and lifts to 0 — the hard seam it always played.
 //
 // v12 (CURRENT WRITE FORMAT) is v11 PLUS the velocity->PITCH transfer curve (count + points,
 // the same shape as v7's), appended after the loop crossfade. Its y is a normalized fraction
 // of kVelocityPitchRangeSemitones (play_params.h) — a full-scale constant that lives OUTSIDE
 // this frozen ladder, so retuning it re-tunes every saved v12 project's pitch-curve throw. It
 // also RE-TAGS the DOMAIN of one frozen slot inside the v9 filter tail: that curve's y is read
 // as BIPOLAR [-1,+1] from v12 on, having been UNIPOLAR [0,1] before. Every other filter slot,
 // velAmount included, keeps its meaning — the cutoff contribution is still
 // velAmount * curve(velocity).
 // PRE-v12 LIFT: a domain re-tag and nothing more. A pre-v12 curve's stored y values all lie in
 // [0,1], which is inside [-1,+1], so the widened box-clamp alters no knot and eval is unchanged
 // at every velocity — a pre-v12 project sounds identical without any rounding argument. A
 // pre-v12 blob carries no pitch curve at all and lifts to the bipolar flat-at-zero default,
 // which transposes nothing. A DOWNGRADE to a pre-v12 binary re-narrows the domain, so a curve
 // drawn into the negative half comes back with that half clamped to 0.
 //
 // The two int64 slots the v5 play tail spends on the RETIRED Trigger fade pair are frozen in
 // shape and still read: a pre-v10 blob's fade-in/fade-out become the Trigger AHD that replaced
@@ -120,7 +135,7 @@ inline constexpr std::uint32_t kPerformanceStateVersion = 2;
 // The params-payload format version and its detection marker. The marker is a high sentinel
 // no legitimate v1 zone count (bounded by 128 MIDI zones, always tiny) could ever equal, so
 // a reader detects record shape independent of the envelope version.
-inline constexpr std::uint32_t kParamsPayloadVersion = 11;  // v10 + the loop-crossfade tail
+inline constexpr std::uint32_t kParamsPayloadVersion = 12;  // v11 + the velocity->pitch curve
 inline constexpr std::uint32_t kParamsFormatMarker = 0xFFFFFF00u;
 // The first SINGLE-RECORD payload version. Everything below it is a retired zone list and
@@ -139,6 +154,11 @@ inline constexpr std::uint32_t kParamsCurveVersion = 10;
 // v10 + the loop-crossfade frame count.
 inline constexpr std::uint32_t kParamsLoopVersion = 11;
 // v11 + the velocity->pitch curve; the appended tail branches on THIS, never on
 // kParamsPayloadVersion. The filter curve's v12 domain re-tag needs no branch of its own — a
 // pre-v12 curve's y values are already valid bipolar ones.
 inline constexpr std::uint32_t kParamsVelocityVersion = 12;
 // (No nominal-rate constant.) The legacy v3 payload's wall-clock frame counts convert to
 // seconds at the v3 read boundary using the PROJECT sample rate threaded in as a parameter
 // (frames / projectRate = seconds) — the same rate the build already receives, so the
@@ -38,14 +38,15 @@ void putOverrides(std::vector<std::uint8_t>& out, const InstrumentParams& p) {
    if (p.startPoint) putLE(out, asU64(*p.startPoint));
 }
-// A velocity curve: 4-byte LE control-point count, then per point velocity + amp as doubles.
+// A velocity curve: 4-byte LE control-point count, then per point velocity + value as doubles.
-// The amp curve (v7) and the filter's own curve (v9) share this shape.
+// The amp curve (v7), the filter's own curve (v9) and the pitch curve (v12) share this shape;
 // the y DOMAIN is not on the wire — it is a property of the slot, so the reader supplies it.
 void putCurve(std::vector<std::uint8_t>& out, const VelocityCurve& curve) {
    const std::vector<VelocityPoint>& pts = curve.points();
    putLE(out, static_cast<std::uint32_t>(pts.size()));
    for (const VelocityPoint& pt : pts) {
        putLE(out, doubleToBits(pt.velocity));
-        putLE(out, doubleToBits(pt.amp));
+        putLE(out, doubleToBits(pt.value));
    }
 }
@@ -92,9 +93,11 @@ void readSecondsPlayTail(ByteReader& r, InstrumentParams& p, double projectRate)
    p.play.adsr.releaseSeconds = bitsToDouble(r.u64());
 }
-// Read a velocity curve tail into `curve`. fromPoints repairs the X-order/endpoint invariant
+// Read a velocity curve tail into `curve`, interpreting its y values in `domain` — the domain
-// defensively; a truncated read leaves `curve` at whatever default it came in with.
+// is not on the wire, it is a property of the slot. fromPoints repairs the X-order/endpoint
-void readCurveTail(ByteReader& r, VelocityCurve& curve) {
+// invariant defensively; a truncated read leaves `curve` at whatever default it came in with.
 void readCurveTail(ByteReader& r, VelocityCurve& curve,
                   reasampler::instrument::engine::CurveDomain domain) {
    const std::uint32_t ptCount = r.u32();
    std::vector<VelocityPoint> pts;
    // Bound the reserve to what the blob can hold (16 bytes/point) so a corrupt huge count
@@ -103,16 +106,18 @@ void readCurveTail(ByteReader& r, VelocityCurve& curve) {
    pts.reserve(std::min(static_cast<std::size_t>(ptCount), remaining / 16));
    for (std::uint32_t i = 0; i < ptCount && r.ok; ++i) {
        const double vel = bitsToDouble(r.u64());
-        const double amp = bitsToDouble(r.u64());
+        const double value = bitsToDouble(r.u64());
-        pts.push_back(VelocityPoint{vel, amp});
+        pts.push_back(VelocityPoint{vel, value});
    }
    if (r.ok) {
-        curve = reasampler::instrument::engine::VelocityCurve::fromPoints(std::move(pts));
+        curve = reasampler::instrument::engine::VelocityCurve::fromPoints(std::move(pts), domain);
    }
 }
 // Read the v9 filter tail into `p`. A blob that stops short leaves the off/neutral default,
-// which is what makes a v8 blob play bit-identically under the new codec.
+// which is what makes a v8 blob play bit-identically under the new codec. The curve reads as
 // bipolar at EVERY version — a pre-v12 blob's y values are already valid bipolar ones, so its
 // v12 domain re-tag needs no version branch (see component_state_io.h).
 void readFilterTail(ByteReader& r, InstrumentParams& p) {
    FilterSeconds& f = p.play.filter;
    f.enabled = (r.u8() != 0);
@@ -135,7 +140,7 @@ void readFilterTail(ByteReader& r, InstrumentParams& p) {
    f.env.decaySeconds   = bitsToDouble(r.u64());
    f.env.sustainLevel   = bitsToDouble(r.u64());
    f.env.releaseSeconds = bitsToDouble(r.u64());
-    readCurveTail(r, f.velocityCurve);
+    readCurveTail(r, f.velocityCurve, reasampler::instrument::engine::CurveDomain::Bipolar);
 }
 // A curve exponent off the wire. A corrupt/non-finite value degrades to the LINEAR neutral
@@ -240,7 +245,10 @@ PayloadRead readLegacyZonePayload(ByteReader& r, std::uint32_t pv, double projec
        // A pre-v6 payload leaves keyTrack = 1.0 (100% ET), so an already-saved instance
        // repitches BIT-IDENTICALLY. A pre-v7 payload leaves VelocityCurve::flat().
        if (keyTrackTail) p.keyTrack = bitsToDouble(r.u64());
-        if (curveTail) readCurveTail(r, p.velocityCurve);
+        if (curveTail) {
            readCurveTail(r, p.velocityCurve,
                          reasampler::instrument::engine::CurveDomain::Unipolar);
        }
        // Payload version 4 (a branch-only frames tail, never shipped) and any unknown pv
        // leave the seconds product defaults on p.play.
        if (!r.ok) break;  // truncated mid-record -> keep what parsed cleanly, drop the rest
@@ -321,6 +329,8 @@ void putParamsPayload(std::vector<std::uint8_t>& out, const InstrumentParams& p)
    putAhd(out, f.trigEnv);
    // v11: the loop crossfade, in SOURCE frames.
    putLE(out, asU64(p.loopCrossfadeFrames));
    // v12: the velocity->pitch curve.
    putCurve(out, pp.pitchVelocityCurve);
 }
 // Read whichever payload shape follows: the single-record shape (v8 onward, growing by
@@ -350,7 +360,7 @@ PayloadRead readParamsPayload(ByteReader& r, double projectRate) {
    if (hasStart) p.startPoint = r.i64();
    readSecondsPlayTail(r, p, projectRate);
    p.keyTrack = bitsToDouble(r.u64());
-    readCurveTail(r, p.velocityCurve);
+    readCurveTail(r, p.velocityCurve, reasampler::instrument::engine::CurveDomain::Unipolar);
    if (pv >= kParamsFilterVersion) readFilterTail(r, p);
    if (pv >= kParamsCurveVersion) readCurveStageTail(r, p);
    if (pv >= kParamsLoopVersion) {
@@ -359,6 +369,10 @@ PayloadRead readParamsPayload(ByteReader& r, double projectRate) {
        const std::int64_t xf = r.i64();
        p.loopCrossfadeFrames = xf > 0 ? xf : 0;
    }
    if (pv >= kParamsVelocityVersion) {
        readCurveTail(r, p.play.pitchVelocityCurve,
                      reasampler::instrument::engine::CurveDomain::Bipolar);
    }
    // A truncated record leaves whatever parsed plus construction defaults for the rest —
    // the same degrade-don't-throw contract the zone ladder always had.
    if (!r.ok) return PayloadRead{};
@@ -238,6 +238,7 @@ PlayParams resolvePlay(const PlaySeconds& stored, int sampleRate) {
    out.pitchEnv.enabled       = stored.pitchEnv.enabled;
    out.pitchEnv.peakSemitones = stored.pitchEnv.peakSemitones;  // depth, not a time
    out.pitchEnv.shape         = resolveAhd(stored.pitchEnv.shape);
    out.pitchVelocityCurve     = stored.pitchVelocityCurve;  // transfer curve, not a time
    // Filter: the control positions are already rate-free and carry through untouched; only
    // its envelope resolves to frames.
    out.filter.enabled   = stored.filter.enabled;
@@ -187,7 +187,7 @@ struct FilterSeconds {
    double keyTrack  = 0.0;
    AdsrSeconds env{0.0, 0.0, 0.0, 1.0, 0.0};  // Gate
    AhdSeconds  trigEnv;                       // Trigger
-    VelocityCurve velocityCurve = VelocityCurve::linear();
+    VelocityCurve velocityCurve = VelocityCurve::zero();
 };
 // The stored play bundle: wall-clock times in SECONDS, source-timeline quantities in
@@ -200,6 +200,7 @@ struct PlaySeconds {
    AhdSeconds      trigAhd;                              // Trigger amp: AHD (seconds + fraction)
    PitchEngine     pitchEngine = kDefaultPitchEngine;    // product default: Preserve
    PitchEnvSeconds pitchEnv;                             // AHD pitch modulation, off by default
    VelocityCurve   pitchVelocityCurve = VelocityCurve::zero();  // velocity -> pitch, off by default
    FilterSeconds   filter;                               // per-voice filter, off by default
 };
@@ -57,4 +57,6 @@ reasampler_pure_library(deck_groups
 reasampler_test(deck_groups LINK deck_groups sample_bands)
 reasampler_pure_library(curve_popup SOURCES curve_popup.cpp LINK PUBLIC editor_geometry)
-reasampler_test(curve_popup LINK curve_popup)
+# velocity_curve is linked for the test only: the sheet's geometry is domain-agnostic, and
 # proving that takes a curve of each domain mapped through the one curveBox.
 reasampler_test(curve_popup LINK curve_popup velocity_curve)
@@ -1,4 +1,5 @@
-// curve_popup.h — sheet geometry + dismissal test for the velocity-curve popup editor.
+// curve_popup.h — sheet geometry + dismissal test for the velocity-curve popup editor, shared
 // by all three curves: the sheet is domain-agnostic, and only the curve's own y map differs.
 // Mirror of overflow_menu; the shell draws through the L1 kit and routes clicks via
 // these rects.
 //
@@ -89,6 +89,17 @@ std::vector<DeckGroupDesc> sampleDeckGroups(PlayMode playMode) {
        }
        out.push_back(std::move(amp));
    }
    {
        // The three velocity transfer curves share one home, immediately left of VOICE: they
        // shape three different destinations but are one gesture, and MASTER is reserved for
        // post-voice-mixer concerns.
        DeckGroupDesc vel;
        vel.id = kGroupVelocity;
        vel.captionWidth = 54;
        vel.cellIds = {id(DeckParam::kAmpVelCurve), id(DeckParam::kPitchVelCurve),
                       id(DeckParam::kFilterVelCurve)};
        out.push_back(std::move(vel));
    }
    {
        DeckGroupDesc voice;
        voice.id = kGroupVoice;
@@ -108,6 +119,15 @@ std::vector<DeckGroupDesc> sampleDeckGroups(PlayMode playMode) {
    return out;
 }
 CurveTarget curveTargetFor(int controlId) {
    switch (static_cast<DeckParam>(controlId)) {
        case DeckParam::kAmpVelCurve:    return CurveTarget::kAmp;
        case DeckParam::kPitchVelCurve:  return CurveTarget::kPitch;
        case DeckParam::kFilterVelCurve: return CurveTarget::kFilter;
        default:                         return CurveTarget::kNone;
    }
 }
 DeckParam curveParamFor(DeckParam knob) {
    switch (knob) {
        case DeckParam::kAttack:            return DeckParam::kAttackCurve;
@@ -145,6 +165,7 @@ bool isLiveDeckParam(DeckParam id) {
        case DeckParam::kFilterQ:
        case DeckParam::kFilterDrive:
        case DeckParam::kFilterModAmt:
        case DeckParam::kFilterVel:
        case DeckParam::kFilterKeyTrack:
        case DeckParam::kFilterEnvAttack:
        case DeckParam::kFilterEnvHold:
@@ -176,7 +197,9 @@ bool isLiveDeckParam(DeckParam id) {
        case DeckParam::kPitchEnvEnable:
        case DeckParam::kKeyTrack:
        case DeckParam::kFilterEnable:
-        case DeckParam::kFilterVel:
+        case DeckParam::kAmpVelCurve:
        case DeckParam::kPitchVelCurve:
        case DeckParam::kFilterVelCurve:
        case DeckParam::kFilterLaw:
        case DeckParam::kAmpEnvSelect:
        case DeckParam::kPitchEnvSelect:
@@ -217,6 +240,37 @@ bool overlayEnvInert(OverlayEnv env, bool pitchEnvEnabled, bool filterEnabled) {
    return false;  // unreachable for a valid enumerator; silences a warning.
 }
 bool deckKnobInert(DeckParam id, bool pitchEnvEnabled, bool filterEnabled) {
    switch (id) {
        case DeckParam::kPitchEnvAttack:
        case DeckParam::kPitchEnvHold:
        case DeckParam::kPitchEnvDecay:
        case DeckParam::kPitchEnvDepth:
            return !pitchEnvEnabled;
        case DeckParam::kFilterMorph:
        case DeckParam::kFilterCutoff:
        case DeckParam::kFilterQ:
        case DeckParam::kFilterDrive:
        case DeckParam::kFilterModAmt:
        case DeckParam::kFilterVel:
        case DeckParam::kFilterKeyTrack:
        // The filter's velocity curve sits in the VELOCITY group but is a filter parameter:
        // it goes inert with every other one, so no surface can reach a param the knobs can't.
        case DeckParam::kFilterVelCurve:
        case DeckParam::kFilterEnvAttack:
        case DeckParam::kFilterEnvHold:
        case DeckParam::kFilterEnvDecay:
        case DeckParam::kFilterEnvSustain:
        case DeckParam::kFilterEnvRelease:
        case DeckParam::kFilterTrigAttack:
        case DeckParam::kFilterTrigHold:
        case DeckParam::kFilterTrigDecay:
            return !filterEnabled;
        default:
            return false;
    }
 }
 bool liveCommitFor(LiveDragKind kind, int paramId) {
    switch (kind) {
        case LiveDragKind::kDeckKnob:
@@ -40,7 +40,7 @@ enum class DeckParam {
    kFilterQ,        // resonance
    kFilterDrive,    // in-loop drive depth
    kFilterModAmt,   // filter envelope -> cutoff, +/-100%
-    kFilterVel,      // velocity -> cutoff, +/-100%
+    kFilterVel,      // velocity curve -> cutoff depth, +/-100%
    kFilterKeyTrack, // note -> cutoff, 0..200%
    kFilterLaw,      // morph law row toggle: HP-BP-LP | HP-notch-LP
    kFilterEnvAttack,   // filter AHDSR (Gate)
@@ -65,6 +65,11 @@ enum class DeckParam {
    kFilterEnvReleaseCurve,
    kFilterTrigAttackCurve,
    kFilterTrigDecayCurve,
    // VELOCITY: the three transfer-curve cells. Each opens the curve popup rather than
    // dragging a value — see curveTargetFor, which is also what tells a cell apart from a knob.
    kAmpVelCurve,
    kPitchVelCurve,
    kFilterVelCurve,
    // Overlay selection radios — transient view state, not parameters.
    kAmpEnvSelect,
    kPitchEnvSelect,
@@ -86,10 +91,19 @@ enum DeckGroupId {
    kGroupFilter,
    kGroupFilterEnv,
    kGroupAmpEnv,
    kGroupVelocity,
    kGroupVoice,
    kGroupMaster,
 };
 // Which velocity curve a deck cell edits, or kNone when the control is an ordinary knob. THE
 // one place a control id resolves to a curve target — paint (draw a curve thumbnail, not a
 // dial) and hit-test (open a popup, not start a drag) both read this predicate rather than
 // re-deriving which ids are curve cells. What each resolved target then shows (which stored
 // curve, which title) is a separate switch — see the shell's curveFor/curveTitle.
 enum class CurveTarget { kNone, kAmp, kPitch, kFilter };
 CurveTarget curveTargetFor(int controlId);
 // The deck's groups, left to right, in SIGNAL-FLOW order: pitch -> filter -> amp, then the
 // two instance-wide groups. `playMode` picks the AMP and FILTER ENV groups' faces — AHDSR in
 // Gate, AHD in Trigger — via knob_deck's blank-cell reservation (knob_deck.h) so a mode flip
@@ -113,9 +127,11 @@ DeckParam curveParamFor(DeckParam knob);
 //     name a different sound rather than a different setting of one;
 //   - the three capture-anchored overrides (root, loop span, start frame) name positions in
 //     the decoded PCM;
-//   - kKeyTrack and kFilterVel feed values a voice latches at note-on by design (the pitch
+//   - kKeyTrack and the three velocity-curve cells feed values a voice latches at note-on by
-//     ratio and the velocity-curve result), so live delivery would retune or re-gain a note
+//     design (the pitch ratio and the curve results), so live delivery would retune or re-gain
-//     already struck;
+//     a note already struck. kFilterVel is NOT one of them: it is the DEPTH over the filter
 //     curve's latched result, the exact shape kFilterKeyTrack already has over the latched note
 //     number, and it glides through the same base-cutoff ramp;
 //   - kTrigLength resolves playEnd_, a fact about the note, not a setting of it;
 //   - the overlay radios select what the editor DRAWS and reach no parameter at all.
 // Both amp shapes are live: the Trigger fade pair that used to reload folded into the AHD and
@@ -152,6 +168,13 @@ OverlayEnv nextOverlaySelection(OverlayEnv current, int radioId);
 // a param a knob couldn't (envelope_edit.h). Amp has no enable toggle and is never inert.
 bool overlayEnvInert(OverlayEnv env, bool pitchEnvEnabled, bool filterEnabled);
 // Whether a deck knob cell is drawn-but-dead: the pitch envelope's four knobs while it is
 // disabled, and the filter group's tone/modulation knobs (plus its VELOCITY cell, a filter
 // parameter that just sits in that group) while the filter is disabled. Every other id is
 // always live. Mirrors overlayEnvInert's group-toggle-gates-its-knobs shape for the deck's own
 // mouse-down/paint (the shell's deckKnobDisabled is a thin int-id wrapper over this).
 bool deckKnobInert(DeckParam id, bool pitchEnvEnabled, bool filterEnabled);
 // The deck's BIPOLAR knob law: 0.5 of the knob's travel is zero depth, the ends are -1 and
 // +1. Exact inverses, and exact at the centre detent (0.5 -> 0 -> 0.5), so a knob parked at
 // centre can never persist a hair of modulation. Out-of-range norm clamps to the endpoints.
@@ -20,7 +20,7 @@ inline constexpr int kEditorMinWidth = 840;
 inline constexpr int kEditorMinHeight = 620;
 // Chrome band: the toolbar row (title + nav) stacked over the control row (piano strip,
-// preview, velocity knob, curve button, channel toggle). sample_chrome partitions it.
+// preview, velocity knob, channel toggle). sample_chrome partitions it.
 inline constexpr int kTitleHeight = 26;
 inline constexpr int kChromeRowHeight = 52;
@@ -19,12 +19,15 @@ constexpr int kStripBandHeight = 30;
 constexpr int kRunGap = 6;  // between adjacent items of the toolbar run
 constexpr int kChanSegW = 52;
 constexpr int kChanSegH = 18;
 constexpr int kCurveBtnSize = 24;
 constexpr int kVelCellW = 44;
 constexpr int kVelLabelH = 12;
 constexpr int kPreviewBtnW = 64;
 constexpr int kRunButtonH = 24;  // Browse and Preview
 constexpr int kPreviewGlyphMinH = 6;
 constexpr int kPreviewGlyphMaxH = 14;
 constexpr int kPreviewGlyphPad = 4;  // clearance between the glyph and the button edge
 }  // namespace
 ChromeRects chromeRects(const Rect& chrome, int knobSize) {
@@ -39,7 +42,8 @@ ChromeRects chromeRects(const Rect& chrome, int knobSize) {
    const auto topFor = [&row](int h) { return row.y + (row.height - h) / 2; };
    const auto leftOf = [&row](int edge, int w) { return std::max(row.x, edge - w); };
-    // The fixed run, right to left: Browse, Mono|Stereo, curve, velocity cell, preview.
+    // The fixed run, right to left: Browse, Mono|Stereo, velocity cell, preview. The
    // velocity-curve button that used to sit here now lives in the deck's VELOCITY group.
    const int navH = std::min(kRunButtonH, row.height);
    const int navTop = topFor(navH);
    const int navRight = std::max(row.x, row.right() - kPad);
@@ -53,14 +57,9 @@ ChromeRects chromeRects(const Rect& chrome, int knobSize) {
    r.chanMono = Rect::ltrb(leftOf(r.chanStereo.x, kChanSegW), chanTop, r.chanStereo.x,
                            chanTop + kChanSegH);
    const int curveTop = topFor(kCurveBtnSize);
    const int curveRight = leftOf(r.chanMono.x, kRunGap);
    r.curveBtn = Rect::ltrb(leftOf(curveRight, kCurveBtnSize), curveTop, curveRight,
                            curveTop + kCurveBtnSize);
    const int cellH = std::min(row.height, knobSize + kVelLabelH);
    const int cellTop = topFor(cellH);
-    const int cellRight = leftOf(r.curveBtn.x, kRunGap);
+    const int cellRight = leftOf(r.chanMono.x, kRunGap);
    r.velCell = Rect::ltrb(leftOf(cellRight, kVelCellW), cellTop, cellRight, cellTop + cellH);
    const int knobLeft = r.velCell.x + (r.velCell.width - knobSize) / 2;
    r.velKnob = Rect::ltrb(knobLeft, r.velCell.y, knobLeft + knobSize,
@@ -89,4 +88,24 @@ ChromeRects chromeRects(const Rect& chrome, int knobSize) {
    return r;
 }
 PreviewGlyph previewGlyph(const Rect& button) {
    PreviewGlyph g;
    if (button.empty()) return g;
    // Even height so the apex lands exactly on the button's horizontal centre line rather
    // than a half-pixel off it.
    int h = std::min({kPreviewGlyphMaxH, button.height - 2 * kPreviewGlyphPad,
                      button.width - 2 * kPreviewGlyphPad});
    h -= h % 2;
    if (h < kPreviewGlyphMinH) return g;
    const int w = std::max(2, (h * 7) / 8);  // ~equilateral: the classic transport triangle
    const int cx = button.x + button.width / 2;
    const int cy = button.y + button.height / 2;
    g.leftX = cx - w / 2;
    g.apexX = g.leftX + w;
    g.topY = cy - h / 2;
    g.bottomY = g.topY + h;
    g.apexY = cy;
    return g;
 }
 }  // namespace reasampler::instrument::ui
@@ -21,7 +21,6 @@ struct ChromeRects {
    Rect velCell;     // preview-velocity knob cell (knob + label band)
    Rect velKnob;
    Rect velLabel;
    Rect curveBtn;    // opens the velocity-curve popup
    Rect chanMono;
    Rect chanStereo;
    Rect navBrowse;
@@ -32,4 +31,20 @@ struct ChromeRects {
 // `knobSize` is the deck knob square, passed in so this module does not depend on knob_deck.
 ChromeRects chromeRects(const Rect& chrome, int knobSize);
 // A right-pointing play triangle centered in the preview button: the button's whole label.
 // Three vertices, handed straight to one filled-triangle draw. Drawn rather than embedded as a
 // bitmap so it inherits the palette role of whatever interaction state the button is in.
 struct PreviewGlyph {
    int leftX = 0;   // the vertical edge
    int topY = 0;
    int bottomY = 0;
    int apexX = 0;   // the point, on the button's vertical centre line
    int apexY = 0;
    bool empty() const { return apexX <= leftX || bottomY <= topY; }
 };
 // Sized off the button's shorter dimension and clamped, so the glyph stays legible in a squat
 // button and never outgrows a generous one. An unusably small button yields an empty glyph.
 PreviewGlyph previewGlyph(const Rect& button);
 }  // namespace reasampler::instrument::ui
@@ -11,6 +11,7 @@
 #include <cstdint>
 #include <cstdio>   // snprintf (deck value labels)
 #include <string>
 #include <utility>  // std::as_const (the const/non-const editedCurve pair)
 #include <vector>
 #include "core/instrument/engine/filter/filter_params.h"  // the filter's own control laws
@@ -52,7 +53,9 @@ namespace {
 // The ceiling is READ from the overlay's schematic scale rather than restated: the AHDSR
 // schematic anchors a maxed knob at the canvas edge, which only holds while the two agree.
 constexpr double kEnvTimeMaxSeconds = instrument::ui::kGateStageMaxSeconds;
-constexpr double kPitchDepthMaxSemis = 24.0;          // pitch depth throw: +/-24 st, centered
+// Pitch depth throw: +/-kVelocityPitchRangeSemitones, centered. The one throw the pitch
 // envelope's peak and the velocity->pitch curve's full scale both speak (play_params.h).
 constexpr double kPitchDepthMaxSemis = kVelocityPitchRangeSemitones;
 constexpr double kKeyTrackMax = 2.0;                 // key-track slider ceiling (0..200%)
 // The raw stored curve exponent for a curve-dial control id, read DIRECTLY off the field —
@@ -513,6 +516,45 @@ void ReaSamplerEditor::unpackEnvelope(OverlayEnv which, const StageEnvelope& env
    }
 }
 const VelocityCurve& ReaSamplerEditor::curveFor(CurveTarget target) const {
    switch (target) {
        case CurveTarget::kPitch:  return params_.play.pitchVelocityCurve;
        case CurveTarget::kFilter: return params_.play.filter.velocityCurve;
        case CurveTarget::kAmp:
        case CurveTarget::kNone:
            // kNone reads as amp — a valid, harmless choice for a target-agnostic caller (a
            // disabled deck cell still needs SOME curve to draw). editedCurve()'s mutable
            // overload below refuses kNone rather than relying on this fallback to protect amp.
            return params_.velocityCurve;
    }
    return params_.velocityCurve;
 }
 VelocityCurve& ReaSamplerEditor::curveFor(CurveTarget target) {
    return const_cast<VelocityCurve&>(std::as_const(*this).curveFor(target));
 }
 const VelocityCurve& ReaSamplerEditor::editedCurve() const { return curveFor(curvePopup_); }
 VelocityCurve& ReaSamplerEditor::editedCurve() {
    // Refuses kNone rather than aliasing amp (see curvePopup_'s declaration for why); should be
    // unreachable now that every writer of kNone also cancels the drag, but this is the second,
    // independent line of defense.
    if (curvePopup_ == CurveTarget::kNone) {
        static VelocityCurve sink = VelocityCurve::flat();
        return sink;
    }
    return curveFor(curvePopup_);
 }
 void ReaSamplerEditor::closeCurvePopup() {
    curvePopup_ = CurveTarget::kNone;
    if (drag_ == DragKind::kCurveNode) {
        drag_ = DragKind::kNone;
        curvePointIndex_ = -1;
    }
 }
 void ReaSamplerEditor::applyParamControl(int id, double value, int segment) {
    if (id == static_cast<int>(ParamControl::kKeyTrack)) {
        // keyTrack sits beside the play bundle (0..200% over kKeyTrackMax); the knob maps 0..1.
@@ -121,7 +121,7 @@ void ReaSamplerEditor::onMouseUp(int x, int y) {
                         y < curveRect.y - kCurveDragOffMargin ||
                         y > curveRect.bottom() + kCurveDragOffMargin;
        if (off) {
-            params_.velocityCurve.deletePoint(static_cast<std::size_t>(curveIdx));
+            editedCurve().deletePoint(static_cast<std::size_t>(curveIdx));
            hover_ = HoverTarget{};  // stale kCurveNode index would light a shifted node
        }
    }
@@ -139,7 +139,7 @@ void ReaSamplerEditor::resolveHover(int x, int y) {
    HoverTarget h;  // kNone by default
    if (view_ == View::kBrowse) {
        h = hoverBrowse(w, hgt, x, y);
-    } else if (curvePopupOpen_) {  // modal over the face
+    } else if (curvePopup_ != CurveTarget::kNone) {  // modal over the face
        h = hoverCurvePopup(w, hgt, x, y);
    } else {
        const FaceLayout fl = faceLayout(w, hgt);
@@ -131,9 +131,12 @@ void ReaSamplerEditor::onMouseWheel(int delta) {
 void ReaSamplerEditor::onSearchChar(unsigned int ch) {
    // The curve popup: Esc dismisses (checked first — the popup is modal over the face, and
-    // the Browse search cannot hold focus under it).
+    // the Browse search cannot hold focus under it). Esc reaches here unconditionally
-    if (curvePopupOpen_ && ch == 27) {
+    // (editor_platform's WM_CHAR routing), including mid-drag on a curve node — closeCurvePopup
-        curvePopupOpen_ = false;
+    // cancels that drag too, or a subsequent WM_MOUSEMOVE would resolve editedCurve() with the
    // popup already closed.
    if (curvePopup_ != CurveTarget::kNone && ch == 27) {
        closeCurvePopup();
        invalidate();
        return;
    }
@@ -1,6 +1,6 @@
 // editor_input_chrome.cpp — the CHROME band's input: the Browse nav, the preview trigger,
-// the preview-velocity knob grab, the curve-button summon, the channel toggle, and the
+// the preview-velocity knob grab, the channel toggle, and the piano strip's root grab plus
-// piano strip's root grab plus its live drag. Windows-only.
+// its live drag. Windows-only.
 #include "shell/instrument/reasampler_editor.h"
@@ -51,12 +51,6 @@ bool ReaSamplerEditor::mouseDownChrome(const FaceLayout& fl, int x, int y) {
        invalidate();
        return true;
    }
    // The mini curve-preview button: summon the popup editor.
    if (contains(cr.curveBtn, x, y)) {
        curvePopupOpen_ = true;
        invalidate();
        return true;
    }
    if (contains(cr.chanMono, x, y)) {
        channelMode_ = ChannelMode::Mono;
        processor_->setChannelMode(ChannelMode::Mono);
@@ -105,7 +99,6 @@ ReaSamplerEditor::HoverTarget ReaSamplerEditor::hoverChrome(const FaceLayout& fl
    if (selectedId_.empty()) return {};  // empty state — no interactive surfaces beyond nav
    if (contains(cr.preview, x, y)) return {HoverKind::kPreview, -1};
    if (contains(cr.velCell, x, y)) return {HoverKind::kVelKnob, -1};
    if (contains(cr.curveBtn, x, y)) return {HoverKind::kCurveButton, -1};
    if (contains(cr.chanMono, x, y)) return {HoverKind::kChanMono, -1};
    if (contains(cr.chanStereo, x, y)) return {HoverKind::kChanStereo, -1};
    if (!cr.rootStrip.empty()) {
@@ -20,10 +20,10 @@ bool ReaSamplerEditor::handlePopupMouseDown(int w, int h, int x, int y) {
    // While open the sheet is modal over the face — it owns every left-click. Close click /
    // outside-wash click dismiss (outside only when no drag is in flight); in-box clicks
    // route to the curve machinery; anything else on the sheet is swallowed.
-    if (!curvePopupOpen_) return false;
+    if (curvePopup_ == CurveTarget::kNone) return false;
    const CurvePopupLayout pl = computeCurvePopup(w, h);
    if (contains(pl.close, x, y)) {
-        curvePopupOpen_ = false;
+        closeCurvePopup();
        invalidate();
        return true;
    }
@@ -32,7 +32,7 @@ bool ReaSamplerEditor::handlePopupMouseDown(int w, int h, int x, int y) {
        return true;
    }
    if (popupOutsideSheet(pl, x, y) && drag_ == DragKind::kNone) {
-        curvePopupOpen_ = false;
+        closeCurvePopup();
        invalidate();
    }
    return true;
@@ -42,12 +42,12 @@ void ReaSamplerEditor::handleCurveMouseDown(const Rect& r, int x, int y) {
    const VelocityCurve::Box box = curveBoxFromRect(r);
    if (box.width <= 0 || box.height <= 1) return;
-    int idx = params_.velocityCurve.pointAtPixel(box, x, y);
+    int idx = editedCurve().pointAtPixel(box, x, y);
    // Modifier-click (Alt) deletes an interior node — a discrete, final edit committed at once
    // (deletePoint refuses the two endpoints, so an Alt-click on them is a safe no-op).
    if (idx >= 0 && (GetKeyState(VK_MENU) & 0x8000) != 0) {
-        if (params_.velocityCurve.deletePoint(static_cast<std::size_t>(idx))) {
+        if (editedCurve().deletePoint(static_cast<std::size_t>(idx))) {
            hover_ = HoverTarget{};  // a stale kCurveNode index would light a shifted node
            commitAndReload();
        }
@@ -66,8 +66,8 @@ void ReaSamplerEditor::handleCurveMouseDown(const Rect& r, int x, int y) {
        const bool inBox = (x >= box.left && x < box.left + box.width &&
                            y >= box.top  && y < box.top  + box.height);
        if (inBox) {
-            const VelocityPoint p = VelocityCurve::pointFromPixel(box, x, y);
+            const VelocityPoint p = editedCurve().pointFromPixel(box, x, y);
-            idx = static_cast<int>(params_.velocityCurve.addPoint(p.velocity, p.amp));
+            idx = static_cast<int>(editedCurve().addPoint(p.velocity, p.value));
        }
    }
@@ -75,7 +75,7 @@ void ReaSamplerEditor::handleCurveMouseDown(const Rect& r, int x, int y) {
    drag_ = DragKind::kCurveNode;
    curvePointIndex_ = idx;
-    dragStartCurve_ = params_.velocityCurve;  // AFTER the add — resolvePointDrag's delta base
+    dragStartCurve_ = editedCurve();  // AFTER the add — resolvePointDrag's delta base
    dragCurveRect_ = r;
    dragStartX_ = x;
    dragStartY_ = y;
@@ -87,7 +87,7 @@ void ReaSamplerEditor::dragCurve(int x, int y) {
    // (box + neighbour-X + endpoint-pin clamps), against the grab-time curve + box (absolute
    // delta — the mirror of the envelope-node drag). Live feedback only; commit on release.
    if (curvePointIndex_ < 0) return;
-    params_.velocityCurve = VelocityCurve::resolvePointDrag(
+    editedCurve() = VelocityCurve::resolvePointDrag(
        dragStartCurve_, static_cast<std::size_t>(curvePointIndex_),
        curveBoxFromRect(dragCurveRect_), x - dragStartX_, y - dragStartY_);
    invalidate();
@@ -98,16 +98,16 @@ void ReaSamplerEditor::onMouseRDown(int x, int y) {
    // and drag-off remain as landed alternates. Commits immediately through the same path as
    // Alt-click; deletePoint's endpoint guard makes an endpoint right-click a safe no-op.
    // Right-clicks act only while the popup is open, and never during an in-flight left drag.
-    if (!processor_ || view_ == View::kBrowse || !curvePopupOpen_) return;
+    if (!processor_ || view_ == View::kBrowse || curvePopup_ == CurveTarget::kNone) return;
    if (drag_ != DragKind::kNone) return;
    RECT rc{};
    GetClientRect(childHwnd_, &rc);
    const CurvePopupLayout pl = computeCurvePopup(rc.right - rc.left, rc.bottom - rc.top);
    if (!contains(pl.curveBox, x, y)) return;
    const VelocityCurve::Box box = curveBoxFromRect(pl.curveBox);
-    const int idx = params_.velocityCurve.pointAtPixel(box, x, y);
+    const int idx = editedCurve().pointAtPixel(box, x, y);
    if (idx < 0) return;
-    if (params_.velocityCurve.deletePoint(static_cast<std::size_t>(idx))) {
+    if (editedCurve().deletePoint(static_cast<std::size_t>(idx))) {
        hover_ = HoverTarget{};  // a stale kCurveNode index would light a shifted node
        commitAndReload();
    }
@@ -120,7 +120,7 @@ ReaSamplerEditor::HoverTarget ReaSamplerEditor::hoverCurvePopup(int w, int h, in
    if (!contains(pl.curveBox, x, y)) return {};
    // A curve node under the pointer lights accent-hot.
    const int idx =
-        params_.velocityCurve.pointAtPixel(curveBoxFromRect(pl.curveBox), x, y);
+        editedCurve().pointAtPixel(curveBoxFromRect(pl.curveBox), x, y);
    if (idx < 0) return {};
    return {HoverKind::kCurveNode, idx};
 }
@@ -17,31 +17,10 @@ using namespace reasampler::ui;
 using namespace reasampler::instrument::ui;
 bool ReaSamplerEditor::deckKnobDisabled(int id) const {
-    switch (static_cast<ParamControl>(id)) {
+    // Thin int-id wrapper over the pure, CTest-covered predicate — see deckKnobInert
-        case ParamControl::kPitchEnvAttack:
+    // (deck_groups.h) for which cells go inert and why.
-        case ParamControl::kPitchEnvHold:
+    return deckKnobInert(static_cast<DeckParam>(id), params_.play.pitchEnv.enabled,
-        case ParamControl::kPitchEnvDecay:
+                         params_.play.filter.enabled);
        case ParamControl::kPitchEnvDepth:
            return !params_.play.pitchEnv.enabled;
        case ParamControl::kFilterMorph:
        case ParamControl::kFilterCutoff:
        case ParamControl::kFilterQ:
        case ParamControl::kFilterDrive:
        case ParamControl::kFilterModAmt:
        case ParamControl::kFilterVel:
        case ParamControl::kFilterKeyTrack:
        case ParamControl::kFilterEnvAttack:
        case ParamControl::kFilterEnvHold:
        case ParamControl::kFilterEnvDecay:
        case ParamControl::kFilterEnvSustain:
        case ParamControl::kFilterEnvRelease:
        case ParamControl::kFilterTrigAttack:
        case ParamControl::kFilterTrigHold:
        case ParamControl::kFilterTrigDecay:
            return !params_.play.filter.enabled;
        default:
            return false;
    }
 }
 bool ReaSamplerEditor::mouseDownDeck(const FaceLayout& fl, int x, int y) {
@@ -96,6 +75,13 @@ bool ReaSamplerEditor::mouseDownDeck(const FaceLayout& fl, int x, int y) {
    if (hit.kind == DeckHitKind::Knob) {
        // Knobs of a disabled group are drawn but inert.
        if (deckKnobDisabled(hit.id)) return true;
        // A VELOCITY cell summons the popup editor instead of starting a knob drag.
        const CurveTarget curveCell = curveTargetFor(hit.id);
        if (curveCell != CurveTarget::kNone) {
            curvePopup_ = curveCell;
            invalidate();
            return true;
        }
        // A grab on the inner disc drags the CURVE control instead, but only where the stage
        // is sloped; on a Hold or Sustain cell the inner region is just more of the knob.
        const ParamControl curve = curveParamFor(static_cast<ParamControl>(hit.id));
@@ -70,7 +70,7 @@ void ReaSamplerEditor::paintSample(LICE_IBitmap* bmp, int w, int h) {
    paintDeck(bmp, fl);
    // The curve popup: a centered sheet over the whole face, drawn last.
-    if (curvePopupOpen_) paintCurvePopup(bmp, w, h);
+    if (curvePopup_ != CurveTarget::kNone) paintCurvePopup(bmp, w, h);
    // The piano strip's note-name chip overhangs its band, so it goes on top of everything.
    paintChromeTooltip(bmp, fl, w, h);
@@ -1,7 +1,7 @@
 // editor_paint_chrome.cpp — the CHROME band's painter: the toolbar row (product title +
-// live readout, then the control run — preview, preview-velocity knob, curve button,
+// live readout, then the control run — preview, preview-velocity knob, Mono|Stereo, Browse)
-// Mono|Stereo, Browse) over the strip row, which the piano strip has to itself. Windows-only;
+// over the strip row, which the piano strip has to itself. Windows-only; all rects come from
-// all rects come from the pure sample_chrome interior and the pure keyboard_strip geometry.
+// the pure sample_chrome interior and the pure keyboard_strip geometry.
 #include "shell/instrument/reasampler_editor.h"
@@ -129,12 +129,23 @@ void ReaSamplerEditor::paintChrome(LICE_IBitmap* bmp, const FaceLayout& fl, bool
    if (empty) return;
    // Preview-trigger button (fires the loaded capture at root through the live voice engine).
    // A drawn play triangle rather than a label or an embedded image: it inherits the button's
    // own foreground role, so it stays legible in every interaction state at no build cost.
    {
        const KitButtonBox box{toKitBox(cr.preview)};
-        const InteractionState st = (previewingNote_ >= 0) ? InteractionState::Active
+        const bool active = (previewingNote_ >= 0);
        const InteractionState st = active ? InteractionState::Active
            : (isHovered(HoverKind::kPreview, -1) ? InteractionState::Hover
                                                  : InteractionState::Rest);
-        drawButton(bmp, box, "Preview", st, /*warn=*/false);
+        drawButton(bmp, box, nullptr, st, /*warn=*/false);
        const PreviewGlyph g = previewGlyph(cr.preview);
        if (!g.empty()) {
            // Same surface as the button label, so the glyph tracks drawButton's own rule
            // (buttonLabelRole) rather than a second copy of it that could desync from the kit.
            const LICE_pixel ink = toLice(roleColor(buttonLabelRole(st)));
            LICE_FillTriangle(bmp, g.leftX, g.topY, g.leftX, g.bottomY, g.apexX, g.apexY,
                              ink, 1.0f, 0);
        }
    }
    // Preview velocity: a radial knob cell (the deck cell grammar), bound to the same
@@ -156,9 +167,6 @@ void ReaSamplerEditor::paintChrome(LICE_IBitmap* bmp, const FaceLayout& fl, bool
        }
    }
    // The mini curve-preview button: opens the popup editor.
    paintCurveButton(bmp, cr.curveBtn);
    // Mono | Stereo output-mode toggle.
    {
        const bool isStereo = (channelMode_ == ChannelMode::Stereo);
@@ -1,6 +1,6 @@
-// editor_paint_curve.cpp — the velocity->amp curve surfaces: the chrome band's mini
+// editor_paint_curve.cpp — the velocity-curve surfaces: the VELOCITY deck group's mini
-// preview button and the modal popup sheet that hosts the full editor. Band-independent
+// thumbnails and the modal popup sheet that hosts the full editor. Band-independent (the
-// (the popup floats over the whole face). Windows-only.
+// popup floats over the whole face). Windows-only.
 #include "shell/instrument/reasampler_editor.h"
@@ -15,28 +15,53 @@ namespace reasampler::vst {
 using namespace reasampler::ui;              // kit vocabulary
 using namespace reasampler::instrument::ui;  // popup geometry
-void ReaSamplerEditor::paintCurveButton(LICE_IBitmap* bmp, const Rect& r) {
+namespace {
 const char* curveTitle(CurveTarget target) {
    switch (target) {
        case CurveTarget::kPitch:  return "VELOCITY -> PITCH";
        case CurveTarget::kFilter: return "VELOCITY -> FILTER";
        case CurveTarget::kAmp:
        case CurveTarget::kNone:
            return "VELOCITY -> AMP";
    }
    return "VELOCITY -> AMP";
 }
 }  // namespace
 void ReaSamplerEditor::paintCurveButton(LICE_IBitmap* bmp, const Rect& r, CurveTarget target,
                                        bool disabled, bool hovered) {
    if (r.width <= 0 || r.height <= 0) return;
    // A hairline-bordered bg/cell square with the live velocity curve traced in miniature
    // (no node markers at this scale). Hover lifts it; it draws Active (accent-primary
    // border) while its popup is open, and re-renders live as the popup edits the curve.
    const bool hov = isHovered(HoverKind::kCurveButton, -1);
    fillSurface(bmp, toKitBox(r), Role::BgCell,
-                hov ? InteractionState::Hover : InteractionState::Rest);
+                disabled ? InteractionState::Disabled
-    const KitColor border = curvePopupOpen_ ? roleColor(Role::AccentPrimary)
+                         : (hovered ? InteractionState::Hover : InteractionState::Rest));
-                                            : roleColor(Role::LineHairline);
+    const KitColor border = (!disabled && curvePopup_ == target)
                                ? roleColor(Role::AccentPrimary)
                                : roleColor(Role::LineHairline);
    LICE_DrawRect(bmp, r.x, r.y, r.width - 1, r.height - 1, toLice(border), 1.0f, 0);
-    const VelocityCurve& curve = params_.velocityCurve;
+    const VelocityCurve& curve = curveFor(target);
    const int inset = 3;
    const VelocityCurve::Box mini{r.x + inset, r.y + inset, r.width - 2 * inset,
                                  r.height - 2 * inset};
    if (mini.width > 1 && mini.height > 1) {
-        const LICE_pixel trace = toLice(roleColor(Role::AccentSecondary));
+        // A bipolar thumbnail gets its zero line, without which a flat-at-zero curve and a
        // flat-at-minimum one would draw identically at this scale.
        if (curve.domain() == instrument::engine::CurveDomain::Bipolar) {
            const int zy = curve.pixelFromPoint(mini, {0.0, 0.0}).y;
            LICE_Line(bmp, mini.left, zy, mini.left + mini.width, zy,
                      toLice(roleColor(Role::LineHairline)), 1.0f, 0, false);
        }
        const LICE_pixel trace =
            toLice(roleColor(disabled ? Role::LineHairline : Role::AccentSecondary));
        int prevX = 0, prevY = 0;
        for (int px = 0; px <= mini.width; ++px) {
            const int mx = mini.left + px;
-            const double vel = VelocityCurve::pointFromPixel(mini, mx, mini.top).velocity;
+            const double vel = curve.pointFromPixel(mini, mx, mini.top).velocity;
-            const int my = VelocityCurve::pixelFromPoint(mini, {vel, curve.eval(vel)}).y;
+            const int my = curve.pixelFromPoint(mini, {vel, curve.eval(vel)}).y;
            if (px > 0) LICE_Line(bmp, prevX, prevY, mx, my, trace, 1.0f, 0, true);
            prevX = mx;
            prevY = my;
@@ -52,7 +77,7 @@ void ReaSamplerEditor::paintCurvePopup(LICE_IBitmap* bmp, int w, int h) {
    fillSurface(bmp, toKitBox(pl.sheet), Role::BgPanel, InteractionState::Rest);
    LICE_DrawRect(bmp, pl.sheet.x, pl.sheet.y, pl.sheet.width - 1,
                  pl.sheet.height - 1, toLice(roleColor(Role::LineHairline)), 1.0f, 0);
-    kitText(bmp, pl.title, "VELOCITY -> AMP", Font::Micro, Role::TextDim);
+    kitText(bmp, pl.title, curveTitle(curvePopup_), Font::Micro, Role::TextDim);
    {
        const KitButtonBox box{toKitBox(pl.close)};
        const InteractionState st = isHovered(HoverKind::kPopupClose, -1)
@@ -69,26 +94,33 @@ void ReaSamplerEditor::paintVelocityCurve(LICE_IBitmap* bmp, const Rect& r) {
    if (r.width <= 0 || r.height <= 0) return;  // defensive (degenerate rect)
    // The bordered box: a panel surface + hairline border, drawn by palette role. No corner
-    // caption — the popup sheet's own "VELOCITY -> AMP" title labels this context (the popup
+    // caption — the popup sheet's own title labels this context (the popup is the only host).
    // is the only host).
    fillSurface(bmp, toKitBox(r), Role::BgPanel, InteractionState::Rest);
    LICE_DrawRect(bmp, r.x, r.y, r.width - 1, r.height - 1,
                  toLice(roleColor(Role::LineHairline)), 1.0f, 0);
    const VelocityCurve::Box box = curveBoxFromRect(r);
    if (box.width <= 0 || box.height <= 1) return;
-    const VelocityCurve& curve = params_.velocityCurve;
+    const VelocityCurve& curve = editedCurve();
    // A bipolar editor needs its zero axis drawn: it is the whole "off" reading, and without
    // it the default flat curve is indistinguishable from any other flat one.
    if (curve.domain() == instrument::engine::CurveDomain::Bipolar) {
        const int zy = curve.pixelFromPoint(box, {0.0, 0.0}).y;
        LICE_Line(bmp, box.left, zy, box.left + box.width, zy,
                  toLice(roleColor(Role::LineHairline)), 1.0f, 0, false);
    }
    // Trace the monotone spline — ONE eval per x column over the mapping box, in the categorical
    // secondary accent (the same grammar as the envelope trace over the waveform). The x ->
-    // velocity and amp -> y mappings both go through the pure module so the trace, the node
+    // velocity and value -> y mappings both go through the pure module so the trace, the node
    // handles, and the hit-test all share one coordinate system.
    const LICE_pixel line = toLice(roleColor(Role::AccentSecondary));
    int prevX = 0, prevY = 0;
    for (int px = 0; px <= box.width; ++px) {
        const int cx = box.left + px;
-        const double vel = VelocityCurve::pointFromPixel(box, cx, box.top).velocity;
+        const double vel = curve.pointFromPixel(box, cx, box.top).velocity;
-        const int cy = VelocityCurve::pixelFromPoint(box, {vel, curve.eval(vel)}).y;
+        const int cy = curve.pixelFromPoint(box, {vel, curve.eval(vel)}).y;
        if (px > 0) LICE_Line(bmp, prevX, prevY, cx, cy, line, 1.0f, 0, true);
        prevX = cx;
        prevY = cy;
@@ -108,7 +140,7 @@ void ReaSamplerEditor::paintVelocityCurve(LICE_IBitmap* bmp, const Rect& r) {
                               dragCurY_ < r.y - kCurveDragOffMargin ||
                               dragCurY_ > r.bottom() + kCurveDragOffMargin);
    for (std::size_t i = 0; i < curve.points().size(); ++i) {
-        const auto np = VelocityCurve::pixelFromPoint(box, curve.points()[i]);
+        const auto np = curve.pixelFromPoint(box, curve.points()[i]);
        const bool grabbed = (drag_ == DragKind::kCurveNode &&
                              curvePointIndex_ == static_cast<int>(i));
        const bool hot = grabbed || isHovered(HoverKind::kCurveNode, static_cast<int>(i));
@@ -78,6 +78,9 @@ void ReaSamplerEditor::paintDeck(LICE_IBitmap* bmp, const FaceLayout& fl) {
            case ParamControl::kFilterModAmt:   return "Mod";
            case ParamControl::kFilterVel:      return "Vel";
            case ParamControl::kFilterKeyTrack: return "Key Trk";
            case ParamControl::kAmpVelCurve:    return "Amp";
            case ParamControl::kPitchVelCurve:  return "Pitch";
            case ParamControl::kFilterVelCurve: return "Filter";
            case ParamControl::kFilterEnvAttack:  return "F.Att";
            case ParamControl::kFilterEnvHold:    return "F.Hold";
            case ParamControl::kFilterEnvDecay:   return "F.Dec";
@@ -102,6 +105,7 @@ void ReaSamplerEditor::paintDeck(LICE_IBitmap* bmp, const FaceLayout& fl) {
            case kGroupPitchEnv:  caption = "PITCH ENV"; break;
            case kGroupFilter:    caption = "FILTER"; break;
            case kGroupFilterEnv: caption = "FILTER ENV"; break;
            case kGroupVelocity:  caption = "VELOCITY"; break;
            case kGroupVoice:     caption = "VOICE"; break;
            case kGroupMaster:    caption = "MASTER"; break;
            default: break;
@@ -169,6 +173,16 @@ void ReaSamplerEditor::paintDeck(LICE_IBitmap* bmp, const FaceLayout& fl) {
        for (const DeckCellLayout& c : g.cells) {
            if (c.id < 0) continue;  // reserved blank cell (the Trigger face's spare)
            const bool disabled = deckKnobDisabled(c.id);
            // A VELOCITY cell is a popup opener, not a dial: it shows its curve in miniature
            // where a knob face would be, and its whole cell is the click target.
            const CurveTarget curveCell = curveTargetFor(c.id);
            if (curveCell != CurveTarget::kNone) {
                paintCurveButton(bmp, c.knob, curveCell, disabled,
                                 !disabled && isHovered(HoverKind::kControl, c.id));
                kitTextCentered(bmp, c.label, knobName(static_cast<ParamControl>(c.id)),
                                Font::Micro, Role::TextDim);
                continue;
            }
            const bool dragging = (drag_ == DragKind::kDeckKnob && dragParamId_ == c.id);
            const bool hov = !disabled && isHovered(HoverKind::kControl, c.id);
            const InteractionState st =
@@ -72,7 +72,7 @@ void ReaSamplerEditor::refreshFromBank() {
    monoTrigger_ = processor_->monoTrigger();
    // A refresh that emptied the selection closes the curve popup — an open-but-invisible
    // modal would otherwise swallow clicks on the empty state.
-    if (selectedId_.empty()) curvePopupOpen_ = false;
+    if (selectedId_.empty()) closeCurvePopup();
    // Drop a filter that names a bank no longer present.
    if (!activeFilterBankId_.empty()) {
        bool found = false;
@@ -86,6 +86,9 @@ private:
    // spelling.
    using OverlayEnv = instrument::ui::OverlayEnv;
    // Which of the three velocity curves a deck cell edits — also the popup's open state.
    using CurveTarget = instrument::ui::CurveTarget;
    // Controls on the setup surface. The int value is the opaque control id the pure
    // knob_deck hit-test returns; the shell maps it to the one parameter set or a
    // processor-side per-instance setter. The id space and the deck's group composition are
@@ -120,7 +123,6 @@ private:
        kCurveNode,       // a velocity-curve control point (index = point index)
        kVelKnob,         // the chrome preview-velocity radial knob
        kStripKey,        // a piano-strip key (index = MIDI note); carries the name tooltip
        kCurveButton,     // the chrome mini curve-preview button (opens the popup)
        kPopupClose,      // the curve popup's Close (x) button
    };
    struct HoverTarget {
@@ -148,7 +150,7 @@ private:
    // --- Band painters (one TU each, mirroring the input side) ---
    // Chrome: title band + Browse nav + the control row (root strip, preview, velocity knob,
-    // curve button, channel toggle).
+    // channel toggle).
    void paintChrome(LICE_IBitmap* bmp, const FaceLayout& fl, bool empty);
    // The hovered piano key's note-name chip. Drawn after every band — it overhangs the
    // chrome into whatever is below it.
@@ -159,11 +161,12 @@ private:
    // label<->value swap on hover/drag.
    void paintDeck(LICE_IBitmap* bmp, const FaceLayout& fl);
-    // The mini curve-preview button (chrome) and the modal curve editor it summons.
+    // A deck cell's mini curve thumbnail (the VELOCITY group) and the modal editor it summons.
-    void paintCurveButton(LICE_IBitmap* bmp, const Rect& r);
+    void paintCurveButton(LICE_IBitmap* bmp, const Rect& r, CurveTarget target, bool disabled,
                          bool hovered);
    void paintCurvePopup(LICE_IBitmap* bmp, int w, int h);
-    // The velocity->amp transfer-curve editor (X = velocity 0-127, Y = amp 0-1); its only
+    // The velocity transfer-curve editor (X = velocity 0-127, Y = the curve's own domain); its
-    // host is the popup sheet. `r` empty -> draws nothing.
+    // only host is the popup sheet. `r` empty -> draws nothing.
    void paintVelocityCurve(LICE_IBitmap* bmp, const Rect& r);
    // Traces the amp-envelope overlay + its draggable node handles over `waveArea`, ONCE at
    // full band height (never per lane).
@@ -456,8 +459,24 @@ private:
    // delta from this anchor, so a grab never jumps the value.
    double dragKnobStartValue_ = 0.0;
-    // Curve popup open flag, never persisted.
+    // Which velocity curve the popup is editing; kNone = closed. Never persisted. Every writer
-    bool curvePopupOpen_ = false;
+    // of kNone must also cancel a live curve-node drag (closeCurvePopup does both) — an Esc
    // mid-drag that closed the popup without cancelling the drag used to leave editedCurve()'s
    // mutable overload aliasing the amp curve underneath an in-flight pitch/filter drag.
    CurveTarget curvePopup_ = CurveTarget::kNone;
    void closeCurvePopup();
    // THE one switch from a CurveTarget to the parameter-set curve it names — paint (button
    // thumbnails, for every target) and edit (editedCurve, for curvePopup_ specifically) both
    // route through it, so a fourth curve or a moved field is a one-place edit.
    const VelocityCurve& curveFor(CurveTarget target) const;
    VelocityCurve& curveFor(CurveTarget target);
    // The curve curvePopup_ names — curveFor(curvePopup_), typed as its own pair because every
    // edit path needs the mutable overload and paint needs the const one. The mutable overload
    // refuses kNone (a closed popup has nothing open to edit) rather than aliasing amp.
    VelocityCurve& editedCurve();
    const VelocityCurve& editedCurve() const;
    // Peak-thumbnail cache (mirror of bank_panel), keyed by "id|binCount" so a resize
    // recomputes at the new width. Cleared on refresh so a stale sample never shows.
@@ -214,14 +214,15 @@ void drawButton(LICE_IBitmap* bmp, const KitButtonBox& button, const char* label
                   radius, toLice(borderCol), drawAlpha(borderCol), 0, true);
    if (label && *label) {
-        // Active fill is the accent — label goes in bg/base for contrast; else text/primary.
+        text(bmp, b, label, Font::Label, buttonLabelRole(state), Align::Center);
        const Role textRole = (state == InteractionState::Active)
                                  ? Role::BgBase
                                  : Role::TextPrimary;
        text(bmp, b, label, Font::Label, textRole, Align::Center);
    }
 }
 Role buttonLabelRole(InteractionState state) {
    // Active fill is the accent — the mark goes in bg/base for contrast; else text/primary.
    return state == InteractionState::Active ? Role::BgBase : Role::TextPrimary;
 }
 void drawSlider(LICE_IBitmap* bmp, const SliderGeometry& geom, InteractionState state) {
    if (!bmp || geom.track.empty()) return;
@@ -87,6 +87,11 @@ void fillSurface(LICE_IBitmap* bmp, const KitBox& box, Role role, InteractionSta
 void drawButton(LICE_IBitmap* bmp, const KitButtonBox& button, const char* label,
                InteractionState state, bool warn);
 // THE ink role drawButton's own label draws in, for `state` (see draw_kit.cpp). A non-text
 // button mark (e.g. a drawn glyph, not text()) that needs to sit legibly on a drawButton
 // surface should call this rather than re-deriving the rule.
 Role buttonLabelRole(InteractionState state);
 // A horizontal slider: track groove, accent-filled portion up to the handle, and the
 // handle itself. `geom` is the pure SliderGeometry the caller computed.
 void drawSlider(LICE_IBitmap* bmp, const SliderGeometry& geom, InteractionState state);
@@ -134,7 +134,7 @@ static void putRecordBody(std::vector<std::uint8_t>& out, const Zone& z, std::ui
        const std::vector<VelocityPoint> pts =
            z.curve.empty() ? std::vector<VelocityPoint>{{0.0, 1.0}, {127.0, 1.0}} : z.curve;
        u32v(out, static_cast<std::uint32_t>(pts.size()));
-        for (const VelocityPoint& p : pts) { f64v(out, p.velocity); f64v(out, p.amp); }
+        for (const VelocityPoint& p : pts) { f64v(out, p.velocity); f64v(out, p.value); }
    }
 }
@@ -281,7 +281,8 @@ static void testComponentStateRoundTrip() {
    in.params.startPoint = 5;
    in.params.keyTrack = 1.5;
    in.params.velocityCurve = reasampler::instrument::engine::VelocityCurve::fromPoints(
-        {VelocityPoint{0.0, 0.2}, VelocityPoint{64.0, 0.6}, VelocityPoint{127.0, 1.0}});
+        {VelocityPoint{0.0, 0.2}, VelocityPoint{64.0, 0.6}, VelocityPoint{127.0, 1.0}},
        reasampler::instrument::engine::CurveDomain::Unipolar);
    in.params.play.playMode = PlayMode::Trigger;
    in.params.play.adsr.attackSeconds = 0.01;
    in.params.play.adsr.holdSeconds = 0.05;
@@ -422,7 +423,8 @@ static void testGoldenFullBlobFixture() {
    in.params.startPoint = 250;
    in.params.keyTrack = 0.5;
    in.params.velocityCurve = reasampler::instrument::engine::VelocityCurve::fromPoints(
-        {VelocityPoint{0.0, 0.2}, VelocityPoint{64.0, 0.6}, VelocityPoint{127.0, 1.0}});
+        {VelocityPoint{0.0, 0.2}, VelocityPoint{64.0, 0.6}, VelocityPoint{127.0, 1.0}},
        reasampler::instrument::engine::CurveDomain::Unipolar);
    in.params.play.playMode = PlayMode::Trigger;
    in.params.play.adsr.attackSeconds = 0.01;
    in.params.play.adsr.holdSeconds = 0.05;
@@ -450,7 +452,7 @@ static void testGoldenFullBlobFixture() {
        0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0x00,0x00,
        0x00,0x05,0x00,0x00,0x00,0x53,0x6e,0x61,0x72,0x65,0x13,0x00,0x00,0x00,0x67,0x75,
        0x69,0x64,0x2d,0x31,0x32,0x33,0x34,0x2d,0x35,0x36,0x37,0x38,0x2d,0x61,0x62,0x63,
-        0x64,0x04,0x00,0x00,0x00,0x6b,0x69,0x63,0x6b,0x00,0xff,0xff,0xff,0x0b,0x00,0x00,
+        0x64,0x04,0x00,0x00,0x00,0x6b,0x69,0x63,0x6b,0x00,0xff,0xff,0xff,0x0c,0x00,0x00,
        0x00,0x01,0x24,0x00,0x00,0x00,0x01,0x01,0xe8,0x03,0x00,0x00,0x00,0x00,0x00,0x00,
        0x88,0x13,0x00,0x00,0x00,0x00,0x00,0x00,0x01,0xfa,0x00,0x00,0x00,0x00,0x00,0x00,
        0x00,0x01,0x9a,0x99,0x99,0x99,0x99,0x99,0xa9,0x3f,0x00,0x00,0x00,0x00,0x00,0x00,
@@ -479,11 +481,11 @@ static void testGoldenFullBlobFixture() {
        0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,         // env decay   0.0
        0x00,0x00,0x00,0x00,0x00,0x00,0xf0,0x3f,         // env sustain 1.0
        0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,         // env release 0.0
-        0x02,0x00,0x00,0x00,                             // filter curve: 2 points (linear)
+        0x02,0x00,0x00,0x00,                             // filter curve: 2 points (flat at zero)
        0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,         //   velocity   0.0
-        0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,         //   amp        0.0
+        0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,         //   value      0.0
        0x00,0x00,0x00,0x00,0x00,0xc0,0x5f,0x40,         //   velocity 127.0
-        0x00,0x00,0x00,0x00,0x00,0x00,0xf0,0x3f,         //   amp        1.0
+        0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,         //   value      0.0
        // --- payload v10 staged-curve tail, at its NEUTRAL default (this fixture sets no
        // curve or AHD field), in the header's documented order ---
        0x00,0x00,0x00,0x00,0x00,0x00,0xf0,0x3f,         // amp attack curve   1.0
@@ -507,6 +509,12 @@ static void testGoldenFullBlobFixture() {
        0x00,0x00,0x00,0x00,0x00,0x00,0xf0,0x3f,         // filt AHD dec curve 1.0
        // --- payload v11 loop-crossfade tail ---
        0x00,0x01,0x00,0x00,0x00,0x00,0x00,0x00,         // loopCrossfadeFrames 256
        // --- payload v12 velocity->pitch curve, at its off default (flat at zero) ---
        0x02,0x00,0x00,0x00,                             // 2 points
        0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,         //   velocity   0.0
        0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,         //   value      0.0
        0x00,0x00,0x00,0x00,0x00,0xc0,0x5f,0x40,         //   velocity 127.0
        0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,         //   value      0.0
    };
    // clang-format on
    CHECK(bytes.size() == sizeof(kGolden));
@@ -554,16 +562,17 @@ static void testEnvelopePrefixBytesFrozen() {
        CHECK(bytes[4] == 0);  // ChannelMode::Mono
    }
    CHECK(kComponentStateVersion == 11);
-    CHECK(kParamsPayloadVersion == 11);
+    CHECK(kParamsPayloadVersion == 12);
    CHECK(kParamsSingleRecordVersion == 8);
    CHECK(kParamsFormatMarker == 0xFFFFFF00u);
-    // The filter, staged-curve and loop tails rode PAYLOAD bumps, not envelope ones — the two
+    // The filter, staged-curve, loop and velocity tails rode PAYLOAD bumps, not envelope ones
-    // axes stay independent, so a future envelope field cannot collide with any of them on one
+    // — the two axes stay independent, so a future envelope field cannot collide with any of
-    // number.
+    // them on one number.
    CHECK(kParamsFilterVersion > kParamsSingleRecordVersion);
    CHECK(kParamsCurveVersion > kParamsFilterVersion);
    CHECK(kParamsLoopVersion > kParamsCurveVersion);
-    CHECK(kParamsPayloadVersion == kParamsLoopVersion);
+    CHECK(kParamsVelocityVersion > kParamsLoopVersion);
    CHECK(kParamsPayloadVersion == kParamsVelocityVersion);
 }
 // --- The filter tail (payload v9) --------------------------------------------
@@ -601,7 +610,7 @@ static void testV8RecordLiftsToTheOffNeutralFilter() {
    CHECK(f.settings.driveNorm == def.settings.driveNorm);
    CHECK(f.settings.morphLaw == reasampler::instrument::engine::filter::MorphLaw::HighBandLow);
    CHECK(f.modAmount == 0.0);
-    CHECK(f.velAmount == 0.0);
+    for (int v = 0; v <= 127; ++v) CHECK(f.velocityCurve.eval(v) == 0.0);
    CHECK(f.keyTrack == 0.0);
    CHECK(f.env.sustainLevel == 1.0);
    CHECK(f.env.attackSeconds == 0.0 && f.env.decaySeconds == 0.0 &&
@@ -628,15 +637,18 @@ static void testFilterTailRoundTripsLosslessly() {
    f.settings.driveNorm = 0.5f;
    f.settings.morphLaw = reasampler::instrument::engine::filter::MorphLaw::HighNotchLow;
    f.modAmount = -0.625;
-    f.velAmount = 0.5;
+    f.velAmount = 0.875;
    f.keyTrack = 1.5;
    f.env.attackSeconds = 0.031;
    f.env.holdSeconds = 0.062;
    f.env.decaySeconds = 0.125;
    f.env.sustainLevel = 0.25;
    f.env.releaseSeconds = 0.5;
    // Bipolar, and reaching into the negative half the retired unipolar shape could not
    // express: a codec that read this back through the old domain would clamp it to 0.
    f.velocityCurve = reasampler::instrument::engine::VelocityCurve::fromPoints(
-        {VelocityPoint{0.0, 0.1}, VelocityPoint{100.0, 0.4}, VelocityPoint{127.0, 0.9}});
+        {VelocityPoint{0.0, -0.75}, VelocityPoint{100.0, 0.4}, VelocityPoint{127.0, 0.9}},
        reasampler::instrument::engine::CurveDomain::Bipolar);
    // The amp's own curve stays different, so a codec that read one into the other fails here.
    in.params.velocityCurve = reasampler::instrument::engine::VelocityCurve::flat();
@@ -658,11 +670,41 @@ static void testFilterTailRoundTripsLosslessly() {
    CHECK(g.env.sustainLevel == f.env.sustainLevel);
    CHECK(g.env.releaseSeconds == f.env.releaseSeconds);
    CHECK(g.velocityCurve.size() == 3);
-    CHECK(g.velocityCurve.equals(f.velocityCurve));
+    CHECK(g.velocityCurve.domain() == reasampler::instrument::engine::CurveDomain::Bipolar);
    CHECK(g.velocityCurve.eval(0.0) == -0.75);   // the negative half survives the round trip
    CHECK(g.velocityCurve.eval(100.0) == 0.4);
    CHECK(g.velocityCurve.eval(127.0) == 0.9);
    CHECK(out.params.velocityCurve.equals(
        reasampler::instrument::engine::VelocityCurve::flat()));
 }
 // The velocity->PITCH curve (payload v12) is a third, independent slot: it round-trips whole,
 // and neither of the other two leaks into it.
 static void testPitchVelocityCurveRoundTripsIndependently() {
    ComponentState in;
    in.selectionId = "pad";
    in.params.play.pitchVelocityCurve = reasampler::instrument::engine::VelocityCurve::fromPoints(
        {VelocityPoint{0.0, -1.0}, VelocityPoint{64.0, 0.25}, VelocityPoint{127.0, 0.5}},
        reasampler::instrument::engine::CurveDomain::Bipolar);
    in.params.play.filter.velocityCurve = reasampler::instrument::engine::VelocityCurve::fromPoints(
        {VelocityPoint{0.0, 0.2}, VelocityPoint{127.0, -0.6}},
        reasampler::instrument::engine::CurveDomain::Bipolar);
    in.params.velocityCurve = reasampler::instrument::engine::VelocityCurve::linear();
    const ComponentState out =
        deserializeComponentState(serializeComponentState(in), 48000.0);
    const reasampler::instrument::engine::VelocityCurve& p = out.params.play.pitchVelocityCurve;
    CHECK(p.size() == 3);
    CHECK(p.domain() == reasampler::instrument::engine::CurveDomain::Bipolar);
    CHECK(p.eval(0.0) == -1.0);
    CHECK(p.eval(64.0) == 0.25);
    CHECK(p.eval(127.0) == 0.5);
    // The other two slots kept their own values — no cross-talk between the three curves.
    CHECK(out.params.play.filter.velocityCurve.eval(127.0) == -0.6);
    CHECK(out.params.velocityCurve.eval(127.0) == 1.0);
    CHECK(out.params.velocityCurve.eval(0.0) == 0.0);
 }
 // A non-finite modAmount/velAmount/keyTrack (a corrupt blob, or any writer that skipped the
 // same guard the v8 master gain already applies) must lift to the neutral default rather than
 // reach Voice::tickFilterCutoff, where both clamp compares are false against NaN and the
@@ -747,6 +789,7 @@ static void testNegativeCrossfadeOnTheWireLiftsToZero() {
 // output with version N stamped in and the (N+1..current) tails cut. Building the older blobs
 // that way exercises the tolerant-reader path rather than assuming it: if a tail ever stopped
 // being a pure suffix, these would decode as garbage instead of as the documented lift.
 static const std::size_t kVelocityTailBytes = 4 + 2 * 2 * 8;  // v12: the 2-pt pitch curve
 static const std::size_t kLoopTailBytes = 8;        // v11: crossfade, one int64
 static const std::size_t kCurveTailBytes = 19 * 8;  // v10: nineteen doubles
 static const std::size_t kFilterTailBytes =
@@ -775,8 +818,21 @@ static std::vector<std::uint8_t> payloadDowngradedTo(const ComponentState& state
    return bytes;
 }
-// A project saved before this change reopens sounding identical: its loop span still applies
+// Every knot of `lifted` equals `stored`'s BIT for bit — the whole claim of a domain re-tag,
-// and its seam is still hard, at EVERY prior single-record version.
+// which is why this compares with == rather than a tolerance.
 static bool knotsAreIdentical(const reasampler::instrument::engine::VelocityCurve& lifted,
                              const reasampler::instrument::engine::VelocityCurve& stored) {
    if (lifted.size() != stored.size()) return false;
    for (std::size_t i = 0; i < lifted.size(); ++i) {
        if (lifted.points()[i].velocity != stored.points()[i].velocity) return false;
        if (lifted.points()[i].value != stored.points()[i].value) return false;
    }
    return true;
 }
 // A project saved before this change reopens sounding identical: its loop span still applies,
 // its seam is still hard, and velocity still modulates pitch not at all, at EVERY prior
 // single-record version.
 static void testPriorPayloadVersionsLiftToAHardSeam() {
    ComponentState in;
    in.selectionId = "pad";
@@ -792,20 +848,39 @@ static void testPriorPayloadVersionsLiftToAHardSeam() {
    // it — proving the cuts land where the ladder says they do.
    in.params.play.adsr.attackCurve = 4.0;
    in.params.loopCrossfadeFrames = 777;  // present in the bytes only at v11
    // Present in the bytes only at v12: an off-default pitch curve, so a lift that leaked one
    // in from anywhere else fails rather than coincidentally matching the default.
    in.params.play.pitchVelocityCurve = reasampler::instrument::engine::VelocityCurve::fromPoints(
        {VelocityPoint{0.0, 0.5}, VelocityPoint{127.0, 1.0}},
        reasampler::instrument::engine::CurveDomain::Bipolar);
    // The filter's velocity pair, so EVERY version that carries a filter tail (v9..v11) walks
    // the v12 domain re-tag, not just v11 (see testPreV12FilterVelocityLiftsAsAPureDomainReTag
    // for the single-version proof). The knots stay inside [0,1] — what a pre-v12 unipolar
    // curve could actually hold.
    in.params.play.filter.enabled = true;
    in.params.play.filter.modAmount = -0.6251953125;
    in.params.play.filter.velAmount = -0.75;
    const reasampler::instrument::engine::VelocityCurve filterShape =
        reasampler::instrument::engine::VelocityCurve::fromPoints(
            {VelocityPoint{0.0, 0.0}, VelocityPoint{64.0, 0.25}, VelocityPoint{127.0, 1.0}},
            reasampler::instrument::engine::CurveDomain::Bipolar);
    in.params.play.filter.velocityCurve = filterShape;
    struct Case {
        std::uint32_t pv;
        std::size_t cut;
        bool keepsCurveTail;
        bool keepsFilterTail;
    };
    const Case cases[] = {
-        {10, kLoopTailBytes, true},
+        {11, kVelocityTailBytes, true, true},
-        {9, kLoopTailBytes + kCurveTailBytes, false},
+        {10, kVelocityTailBytes + kLoopTailBytes, true, true},
-        {8, kLoopTailBytes + kCurveTailBytes + kFilterTailBytes, false},
+        {9, kVelocityTailBytes + kLoopTailBytes + kCurveTailBytes, false, true},
        {8, kVelocityTailBytes + kLoopTailBytes + kCurveTailBytes + kFilterTailBytes, false, false},
    };
    for (const Case& c : cases) {
-        const ComponentState out =
+        const std::vector<std::uint8_t> bytes = payloadDowngradedTo(in, c.pv, c.cut);
-            deserializeComponentState(payloadDowngradedTo(in, c.pv, c.cut), 48000.0);
+        const ComponentState out = deserializeComponentState(bytes, 48000.0);
        // The span itself has been in the format since v2 and must survive untouched.
        CHECK(out.params.loopOverride && out.params.loopOverride->hasLoop);
        CHECK(out.params.loopOverride && out.params.loopOverride->start == 2000);
@@ -813,14 +888,92 @@ static void testPriorPayloadVersionsLiftToAHardSeam() {
        CHECK(out.params.startPoint && *out.params.startPoint == 128);
        CHECK(out.params.keyTrack == 0.5);
        CHECK(out.params.play.adsr.releaseSeconds == 0.25);
-        // The documented pre-change behaviour: a hard seam.
+        // The documented pre-change behaviour: a hard seam and no velocity->pitch at all.
-        CHECK(out.params.loopCrossfadeFrames == 0);
+        CHECK(out.params.loopCrossfadeFrames == (c.pv >= 11 ? 777 : 0));
        for (int v = 0; v <= 127; ++v) {
            CHECK(out.params.play.pitchVelocityCurve.eval(v) == 0.0);
        }
        // And the cut landed on the tail boundary the ladder claims, not somewhere inside it.
        CHECK(out.params.play.adsr.attackCurve ==
              (c.keepsCurveTail ? 4.0 : reasampler::util::kCurveNeutral));
        // The filter's velocity pair where the tail survives (v9..v11): the depth carries
        // forward untouched and the curve is re-tagged, not rescaled — so the cutoff
        // contribution, depth * curve(v), is exactly what the pre-change reader computed.
        // Where the tail was cut away entirely (v8) it is the off/neutral default.
        if (c.keepsFilterTail) {
            CHECK(out.params.play.filter.enabled);
            CHECK(out.params.play.filter.velAmount == in.params.play.filter.velAmount);
            CHECK(knotsAreIdentical(out.params.play.filter.velocityCurve, filterShape));
            for (int v = 0; v <= 127; ++v) {
                CHECK(out.params.play.filter.velAmount *
                          out.params.play.filter.velocityCurve.eval(v) ==
                      in.params.play.filter.velAmount * filterShape.eval(v));
            }
        } else {
            CHECK(!out.params.play.filter.enabled);
            CHECK(out.params.play.filter.velAmount == 0.0);
            for (int v = 0; v <= 127; ++v) {
                CHECK(out.params.play.filter.velocityCurve.eval(v) == 0.0);
            }
        }
    }
 }
 // The sharp edge of the bipolar change: v12 widened the filter curve's y domain, and the lift
 // is a pure DOMAIN RE-TAG — no rescaling, no rounding. A pre-v12 curve's y values all lie in
 // [0,1], which is inside [-1,+1], so every knot must come back bit-identical, the depth beside
 // it untouched, and the cutoff contribution equal to the pre-change product at every velocity.
 static void testPreV12FilterVelocityLiftsAsAPureDomainReTag() {
    // A shape confined to [0,1] — what a pre-v12 unipolar curve could actually store. The
    // reference reads the SAME knots through the old domain, so the comparison is against what
    // the pre-change reader built, not against another read of the new one.
    const std::vector<VelocityPoint> knots = {VelocityPoint{0.0, 0.0}, VelocityPoint{40.0, 0.125},
                                              VelocityPoint{64.0, 0.75}, VelocityPoint{127.0, 1.0}};
    const reasampler::instrument::engine::VelocityCurve asStored =
        reasampler::instrument::engine::VelocityCurve::fromPoints(
            knots, reasampler::instrument::engine::CurveDomain::Unipolar);
    for (const double depth : {-0.75, 0.5, 0.0}) {
        ComponentState in;
        in.selectionId = "pad";
        FilterSeconds& f = in.params.play.filter;
        f.enabled = true;
        f.modAmount = -0.6251953125;
        f.velAmount = depth;
        f.velocityCurve = reasampler::instrument::engine::VelocityCurve::fromPoints(
            knots, reasampler::instrument::engine::CurveDomain::Bipolar);
        const std::vector<std::uint8_t> bytes =
            payloadDowngradedTo(in, kParamsLoopVersion, kVelocityTailBytes);
        const ComponentState out = deserializeComponentState(bytes, 48000.0);
        const reasampler::instrument::engine::VelocityCurve& lifted =
            out.params.play.filter.velocityCurve;
        CHECK(lifted.domain() == reasampler::instrument::engine::CurveDomain::Bipolar);
        CHECK(knotsAreIdentical(lifted, asStored));       // bit-identical, not within a tolerance
        CHECK(out.params.play.filter.velAmount == depth);  // the depth carries forward untouched
        CHECK(out.params.play.filter.modAmount == f.modAmount);
        // Sound-identical, stated as the product the voice actually computes.
        for (int v = 0; v <= 127; ++v) {
            CHECK(out.params.play.filter.velAmount * lifted.eval(v) == depth * asStored.eval(v));
        }
    }
    // The v12 blob of the same state reads back the same way — the re-tag is what the reader
    // does at EVERY version, so the pre-v12 and current paths cannot diverge.
    ComponentState now;
    now.selectionId = "pad";
    now.params.play.filter.enabled = true;
    now.params.play.filter.velAmount = -0.75;
    now.params.play.filter.velocityCurve =
        reasampler::instrument::engine::VelocityCurve::fromPoints(
            knots, reasampler::instrument::engine::CurveDomain::Bipolar);
    const ComponentState back =
        deserializeComponentState(serializeComponentState(now), 48000.0);
    CHECK(knotsAreIdentical(back.params.play.filter.velocityCurve, asStored));
    CHECK(back.params.play.filter.velAmount == -0.75);
 }
 // The WRITER emits the CURRENT payload version, and the marker + version sit at the head of
 // the payload — the self-describing property every legacy branch depends on. Asserted
 // against the semantic constants, not literals.
@@ -1306,11 +1459,12 @@ static void testSampleRefsTruncatedMidEntry() {
    // The tail after the refs table is instanceGuid(4, empty) + selectionId(4+4="kick") +
    // the current params payload for DEFAULT params (marker4+version4 + overrides3 + the
    // 91-byte play tail + keyTrack8 + curve(4+2*16, the flat 2-point default) + the 134-byte
-    // v9 filter tail + the 160-byte v10 staged-curve tail) = 452 bytes; entry two is 47 bytes
+    // v9 filter tail + the 152-byte v10 staged-curve tail + the 8-byte v11 crossfade + the
-    // (id 4+3, path 4+7, root4, loop 1+8+8, channels4, name 4+0). Cutting 472 keeps the first
+    // 36-byte v12 pitch curve) = 488 bytes; entry two is 47 bytes (id 4+3, path 4+7, root4,
-    // 27 of entry two's 47 — mid loop.start (offset 23..31).
+    // loop 1+8+8, channels4, name 4+0). Cutting 508 keeps the first 27 of entry two's 47 —
-    CHECK(bytes.size() > 472);
+    // mid loop.start (offset 23..31).
-    bytes.resize(bytes.size() - 472);
+    CHECK(bytes.size() > 508);
    bytes.resize(bytes.size() - 508);
    const ComponentState back = deserializeComponentState(bytes, 44100.0);
    CHECK(back.sampleRefs.size() == 1);
    CHECK(back.sampleRefs.size() == 1 && back.sampleRefs[0].sampleId == "kick");
@@ -1393,6 +1547,7 @@ int main() {
    testLoopSpanAndCrossfadeRoundTrip();
    testNegativeCrossfadeOnTheWireLiftsToZero();
    testPriorPayloadVersionsLiftToAHardSeam();
    testPreV12FilterVelocityLiftsAsAPureDomainReTag();
    testWriterEmitsCurrentPayloadVersion();
    testSingleZoneMigrationIsLossless();
    testMigratedFadeContourTracksTheRetiredEqualPowerShape();
@@ -1415,6 +1570,7 @@ int main() {
    testTruncationDegradesCleanly();
    testV8RecordLiftsToTheOffNeutralFilter();
    testFilterTailRoundTripsLosslessly();
    testPitchVelocityCurveRoundTripsIndependently();
    testNonFiniteFilterFieldsLiftToTheNeutralDefault();
    testNonFiniteAhdSecondsLiftToZero();
    if (failures == 0) {
@@ -6,10 +6,15 @@
 #include "../src/core/instrument/ui/curve_popup.h"
 #include "../src/core/instrument/engine/velocity_curve.h"
 #include <algorithm>
 #include <cstdio>
 using namespace reasampler;
 using namespace reasampler::instrument::ui;
 using reasampler::instrument::engine::CurveDomain;
 using reasampler::instrument::engine::VelocityCurve;
 static int g_fail = 0;
 #define CHECK(cond) do { if(!(cond)) { \
@@ -80,7 +85,47 @@ static void testOutsideSheetDismissTest() {
    CHECK(!popupOutsideSheet(pl, pl.sheet.right() - 1, pl.sheet.bottom() - 1));
 }
 // The sheet hosts all three curves, and its box is domain-agnostic: the SAME curveBox drives a
 // unipolar and a bipolar editor, and only the curve's own y map differs. Asserted here, against
 // the popup's real geometry, because that is what makes one popup code path legitimate.
 static void testTheSameCurveBoxHostsBothDomains() {
    const CurvePopupLayout pl = computeCurvePopup(840, 620);
    // The editor never maps against the raw curveBox — shell/instrument/editor_internal.h's
    // curveBoxFromRect insets it first (kVelCurveInset == 14, mirrored here since this pure
    // target cannot link the shell). Applying it, not the raw rect, is what exercises the
    // actual box shape paint/hit-test/drag agree on.
    constexpr int kInset = 14;
    const VelocityCurve::Box box{pl.curveBox.x + kInset, pl.curveBox.y + kInset,
                                 std::max(0, pl.curveBox.width - 2 * kInset),
                                 std::max(0, pl.curveBox.height - 2 * kInset)};
    CHECK(box.width > 1 && box.height > 1);
    const VelocityCurve amp = VelocityCurve::flat();
    const VelocityCurve mod = VelocityCurve::zero();
    const int top = box.top;
    const int bottom = box.top + box.height - 1;
    // Both domains put their MAX on the top row and their MIN on the bottom row...
    CHECK(amp.pixelFromPoint(box, {0.0, 1.0}).y == top);
    CHECK(amp.pixelFromPoint(box, {0.0, 0.0}).y == bottom);
    CHECK(mod.pixelFromPoint(box, {0.0, 1.0}).y == top);
    CHECK(mod.pixelFromPoint(box, {0.0, -1.0}).y == bottom);
    // ...so value 0 is the FLOOR for the amp curve and the MIDLINE for a modulation curve. The
    // expected row replicates valueToY's own HALF-UP rounding on the inverted fraction (velocity_
    // curve.cpp) rather than a plain integer bisection of top/bottom: the two agree only when
    // box.height-1 is even, so a naive (top+bottom)/2 silently depends on this box's parity.
    const int midY = top + static_cast<int>(0.5 * static_cast<double>(box.height - 1) + 0.5);
    CHECK(mod.pixelFromPoint(box, {0.0, 0.0}).y == midY);
    // And a click at the vertical centre adds a point at 0 in the bipolar editor, at 0.5 in
    // the unipolar one — one hit-test path, two correct answers.
    CHECK(mod.pointFromPixel(box, box.left, midY).value == 0.0);
    CHECK(amp.pointFromPixel(box, box.left, midY).value > 0.49);
    CHECK(amp.pointFromPixel(box, box.left, midY).value < 0.51);
 }
 int main() {
    testTheSameCurveBoxHostsBothDomains();
    testDefaultWindowMidClamp();
    testMinClamp();
    testMaxClamp();
@@ -1,7 +1,9 @@
 // Standalone tests for reasampler::instrument::ui::deck_groups — no VST3, no REAPER, no
 // framework. knob_deck's own tests pin how a descriptor list LAYS OUT; these pin WHICH
 // descriptors the Sample face carries: the signal-flow group order (pitch -> filter -> amp),
-// the Filter group's contents, the wrapped deck height at the editor's floor width and its fit
+// the Filter group's contents, the VELOCITY group's exclusive ownership of the three curve
 // cells and its placement immediately left of VOICE, the wrapped deck height at the editor's
 // floor width and its fit
 // inside the floor window, the hit-test reaching the new filter controls, the bipolar knob
 // law's inverse pair, the commit-tier routing — which controls are live, and which drags take
 // the live tier — and the overlay-selection state machine (exclusivity, the none resting state,
@@ -48,13 +50,71 @@ static void testDeckReadsPitchThenFilterThenAmpLeftToRight() {
        CHECK(penv < filt);
        CHECK(filt < fenv);
        CHECK(fenv < amp);
-        // The two instance-wide groups stay at the end.
+        // VELOCITY then the two instance-wide groups at the end. Velocity sits IMMEDIATELY
-        CHECK(amp < indexOfGroup(g, kGroupVoice));
+        // left of VOICE — MASTER is reserved for post-voice-mixer concerns, so the curves
        // must not drift into it.
        const int vel = indexOfGroup(g, kGroupVelocity);
        CHECK(amp < vel);
        CHECK(vel + 1 == indexOfGroup(g, kGroupVoice));
        CHECK(indexOfGroup(g, kGroupVoice) < indexOfGroup(g, kGroupMaster));
    }
 }
-static void testFilterGroupCarriesItsFiveToneControlsPlusModulation() {
+// The three velocity curves live together in VELOCITY and nowhere else: no other group may
 // carry a curve cell, or the "one home" the group exists for is not one.
 static void testVelocityGroupOwnsTheThreeCurvesExclusively() {
    for (PlayMode mode : {PlayMode::Gate, PlayMode::Trigger}) {
        const std::vector<DeckGroupDesc> g = sampleDeckGroups(mode);
        const DeckGroupDesc& v =
            g[static_cast<std::size_t>(indexOfGroup(g, kGroupVelocity))];
        const std::vector<int> expected = {cell(DeckParam::kAmpVelCurve),
                                           cell(DeckParam::kPitchVelCurve),
                                           cell(DeckParam::kFilterVelCurve)};
        CHECK(v.cellIds == expected);
        CHECK(v.captionToggle.id == -1 && v.rowToggle.id == -1 && v.captionRadio.id == -1);
        for (const DeckGroupDesc& d : g) {
            if (d.id == kGroupVelocity) continue;
            for (int id : d.cellIds) CHECK(curveTargetFor(id) == CurveTarget::kNone);
            CHECK(curveTargetFor(d.captionToggle.id) == CurveTarget::kNone);
            CHECK(curveTargetFor(d.rowToggle.id) == CurveTarget::kNone);
        }
    }
 }
 // Each curve cell names its OWN destination, and an ordinary knob names none — the predicate
 // the shell uses to tell a popup opener from a dial.
 static void testCurveTargetNamesEachCellsOwnDestination() {
    CHECK(curveTargetFor(cell(DeckParam::kAmpVelCurve)) == CurveTarget::kAmp);
    CHECK(curveTargetFor(cell(DeckParam::kPitchVelCurve)) == CurveTarget::kPitch);
    CHECK(curveTargetFor(cell(DeckParam::kFilterVelCurve)) == CurveTarget::kFilter);
    CHECK(curveTargetFor(cell(DeckParam::kFilterCutoff)) == CurveTarget::kNone);
    CHECK(curveTargetFor(cell(DeckParam::kMasterGain)) == CurveTarget::kNone);
    CHECK(curveTargetFor(-1) == CurveTarget::kNone);   // a blank reserved cell
    CHECK(curveTargetFor(9999) == CurveTarget::kNone); // out of the id space
 }
 // The cells hit-test inside their own group, from the centre of each cell — the deck grammar
 // treats them as knob cells, so the popup routing rides an ordinary Knob hit.
 static void testVelocityCellsHitTestWithinTheirGroup() {
    const std::vector<DeckGroupDesc> g = sampleDeckGroups(PlayMode::Gate);
    const DeckLayout dl = layoutDeck(g, kPad, 40, kAvailAtMinWidth);
    const DeckGroupLayout& v =
        dl.groups[static_cast<std::size_t>(indexOfGroup(g, kGroupVelocity))];
    CHECK(v.cells.size() == 3);
    const CurveTarget want[] = {CurveTarget::kAmp, CurveTarget::kPitch, CurveTarget::kFilter};
    for (std::size_t i = 0; i < v.cells.size(); ++i) {
        const DeckCellLayout& c = v.cells[i];
        const DeckHit hit = hitTestDeck(dl, c.cell.x + c.cell.width / 2,
                                        c.cell.y + c.cell.height / 2);
        CHECK(hit.kind == DeckHitKind::Knob);
        CHECK(hit.id == c.id);
        CHECK(curveTargetFor(hit.id) == want[i]);
        // Inside its own group box, and the cell the hit resolved is this one.
        CHECK(c.cell.x >= v.box.x && c.cell.right() <= v.box.right());
    }
 }
 static void testFilterGroupCarriesItsToneControlsPlusModulation() {
    const std::vector<DeckGroupDesc>& g = sampleDeckGroups(PlayMode::Gate);
    const DeckGroupDesc& f = g[static_cast<std::size_t>(indexOfGroup(g, kGroupFilter))];
    const std::vector<int> expected = {
@@ -177,10 +237,13 @@ static void testAmpGroupWidthSurvivesAGateTriggerFlip() {
 static void testWrappedDeckHeightAtTheEditorFloorWidth() {
    const std::vector<DeckGroupDesc> g = sampleDeckGroups(PlayMode::Gate);
-    // At the floor (== default) 840 the deck takes two rows: PITCH + PITCH ENV + FILTER fill
+    // At the floor (== default) 840 the deck takes three rows: PITCH + PITCH ENV + FILTER fill
-    // the first, the remaining four fit the second.
+    // the first (818 of the 824 available — six px of headroom, so one more FILTER cell would
-    CHECK(deckRowCount(g, kAvailAtMinWidth) == 2);
+    // wrap the group and reflow everything under it), FILTER ENV + AMP + VELOCITY the second,
-    CHECK(deckHeight(g, kAvailAtMinWidth) == 2 * kDeckGroupH + kDeckRowGap);
+    // VOICE + MASTER the third. Two rows cannot hold the eight groups in ANY order at this
    // width: 1666 px of group plus 72 px of gaps against a 1648 px two-row capacity.
    CHECK(deckRowCount(g, kAvailAtMinWidth) == 3);
    CHECK(deckHeight(g, kAvailAtMinWidth) == 3 * kDeckGroupH + 2 * kDeckRowGap);
    // Whole groups only, never split: every group's box lies inside the available width or is
    // the first of its row.
@@ -272,11 +335,12 @@ static void testBipolarKnobLawRoundTripsAndIsExactAtCentre() {
 }
 static void testEveryDeckControlIsClassifiedLiveOrReloading() {
-    // The live set: the six filter tone/modulation knobs, plus every stage time, stage level,
+    // The live set: the seven filter tone/modulation knobs, plus every stage time, stage level,
    // hold fraction and curve exponent on all three envelopes — in BOTH mode shapes.
    const DeckParam live[] = {
        DeckParam::kFilterMorph, DeckParam::kFilterCutoff, DeckParam::kFilterQ,
-        DeckParam::kFilterDrive, DeckParam::kFilterModAmt, DeckParam::kFilterKeyTrack,
+        DeckParam::kFilterDrive, DeckParam::kFilterModAmt, DeckParam::kFilterVel,
        DeckParam::kFilterKeyTrack,
        DeckParam::kAttack, DeckParam::kHold, DeckParam::kDecay, DeckParam::kSustain,
        DeckParam::kRelease,
        DeckParam::kTrigAttack, DeckParam::kTrigHold, DeckParam::kTrigDecay,
@@ -298,7 +362,8 @@ static void testEveryDeckControlIsClassifiedLiveOrReloading() {
    // is excluded.
    const DeckParam reloads[] = {
        DeckParam::kPlayMode, DeckParam::kPitchEngine, DeckParam::kPitchEnvEnable,
-        DeckParam::kFilterEnable, DeckParam::kFilterLaw, DeckParam::kFilterVel,
+        DeckParam::kFilterEnable, DeckParam::kFilterLaw,
        DeckParam::kAmpVelCurve, DeckParam::kPitchVelCurve, DeckParam::kFilterVelCurve,
        DeckParam::kKeyTrack, DeckParam::kTrigLength,
        DeckParam::kAmpEnvSelect, DeckParam::kPitchEnvSelect, DeckParam::kFilterEnvSelect,
        DeckParam::kVoiceCount, DeckParam::kVoiceMode,
@@ -397,15 +462,36 @@ static void testOverlayIsInertExactlyWhenItsGroupToggleIsOff() {
    CHECK(!overlayEnvInert(OverlayEnv::kNone, false, false));
 }
 // A deck knob goes inert exactly with its group's own enable toggle — including the filter's
 // VELOCITY cell, which sits in the VELOCITY group visually but is a filter parameter and must
 // go inert with the rest of the filter (the reachable-through-the-deck route mouseDownDeck
 // checks before ever routing a curve-cell click to the popup).
 static void testDeckKnobIsInertExactlyWithItsGroupsEnableToggle() {
    CHECK(deckKnobInert(DeckParam::kFilterVelCurve, /*pitchEnv=*/true, /*filter=*/false));
    CHECK(!deckKnobInert(DeckParam::kFilterVelCurve, true, true));
    CHECK(deckKnobInert(DeckParam::kFilterCutoff, true, false));
    CHECK(!deckKnobInert(DeckParam::kFilterCutoff, true, true));
    CHECK(deckKnobInert(DeckParam::kPitchEnvDepth, /*pitchEnv=*/false, true));
    CHECK(!deckKnobInert(DeckParam::kPitchEnvDepth, true, true));
    // The amp's own velocity cell and every ordinary control are never inert here — inertness
    // is a filter/pitch-env-group-only concept.
    CHECK(!deckKnobInert(DeckParam::kAmpVelCurve, false, false));
    CHECK(!deckKnobInert(DeckParam::kAttack, false, false));
 }
 int main() {
    testOverlaySelectionIsExclusiveAcrossTheThreeEnvelopeDecks();
    testClickingTheActiveOverlayRadioClearsToNone();
    testANonRadioIdLeavesTheOverlaySelectionAlone();
    testOverlayIsInertExactlyWhenItsGroupToggleIsOff();
    testDeckKnobIsInertExactlyWithItsGroupsEnableToggle();
    testEveryDeckControlIsClassifiedLiveOrReloading();
    testOnlyALiveControlsDragTakesTheLiveTier();
    testDeckReadsPitchThenFilterThenAmpLeftToRight();
-    testFilterGroupCarriesItsFiveToneControlsPlusModulation();
+    testVelocityGroupOwnsTheThreeCurvesExclusively();
    testCurveTargetNamesEachCellsOwnDestination();
    testVelocityCellsHitTestWithinTheirGroup();
    testFilterGroupCarriesItsToneControlsPlusModulation();
    testOnlyTheThreeEnvelopeDecksCarryARadio();
    testGateAndTriggerFacesCarryTheirOwnShapes();
    testOnlySlopedStageKnobsCarryAnInnerCurveDial();
@@ -63,6 +63,10 @@ static SampleData filteredSine() {
    s.play.filter.settings.cutoffNorm = 0.8f;
    s.play.filter.settings.resonanceNorm = 0.9f;
    s.play.filter.settings.morphNorm = 1.0f;
    // A drawn velocity curve, so the velocity-DEPTH knob has something to scale. It costs
    // every other case nothing: the depth is 0 until a case moves it, so the product is 0.
    s.play.filter.velocityCurve = VelocityCurve::fromPoints(
        {{0.0, 0.0}, {127.0, -1.0}}, instrument::engine::CurveDomain::Bipolar);
    return s;
 }
@@ -601,6 +605,10 @@ static void testEveryLiveFilterControlMovesTheSoundingNote() {
        {"morph",  [](LiveValues& v) { v.filterSettings.morphNorm = 0.0f; }},
        {"drive",  [](LiveValues& v) { v.filterSettings.driveNorm = 1.0f; }},
        {"mod",    [](LiveValues& v) { v.filterModAmount = 1.0; }},
        // The velocity DEPTH is live even though the velocity itself is latched: the depth is
        // a control over the note's latched curve value, the same shape key-track has over the
        // note's latched number (deck_groups.h).
        {"velamount", [](LiveValues& v) { v.filterVelAmount = 1.0; }},
        {"keytrack", [](LiveValues& v) { v.filterKeyTrack = 2.0; }},
    };
@@ -644,7 +652,7 @@ static void testEveryLiveFilterControlMovesTheSoundingNote() {
        // The window is a FRACTION OF THE GLIDE, not a frame count: kLiveRampSeconds is the
        // full travel time, so at 1/240 of it a working glide has barely started when the
        // window closes. kGlideMargin then puts the bound at the geometric middle of the two
-        // MEASURED populations — with the ramp in place these six controls ratio 0.0005..0.060;
+        // MEASURED populations — with the ramp in place these seven controls ratio 0.0005..0.060;
        // with it defeated (every live move delivered as a snap, run) they ratio 0.52..1.10.
        // The bound lands at 0.175: ~3x above the worst glide, ~3x below the tamest snap.
        const std::size_t rampFrames =
@@ -745,6 +753,7 @@ static void testPitchRatioAndVelocityGainStayLatched() {
    hostile.filterKeyTrack = 2.0;
    hostile.filterSettings.cutoffNorm = 0.0f;
    hostile.filterModAmount = 1.0;
    hostile.filterVelAmount = 1.0;
    hostile.pitchEnv.shape.attackFrames = 4800;
    hostile.pitchEnv.shape.decayFrames = 4800;
    hostile.pitchEnv.peakSemitones = 24.0;
@@ -786,14 +795,13 @@ static void testPitchRatioAndVelocityGainStayLatched() {
 static void testVelocityGainSurvivesAHostilePublishThatReallyLands() {
    // Filter AND pitch envelope enabled, so every field the block carries actually reaches the
-    // voice. velAmount is 0, so velocity enters the render exactly once — as the amp gain
+    // voice. The filter and pitch velocity curves are left at their off defaults, so velocity
-    // latched at note-on — which makes two runs at different velocities exactly proportional
+    // enters the render exactly once — as the amp gain latched at note-on — which makes two
-    // unless the publish moved that gain (a re-derived gain would have to preserve the ratio
+    // runs at different velocities exactly proportional unless the publish moved that gain (a
-    // 100:64 to slip through).
+    // re-derived gain would have to preserve the ratio 100:64 to slip through).
    SampleData rig = periodicSine(200000, 64.0);
    rig.velocityCurve = VelocityCurve::linear();
    filterSweep(rig);
    rig.play.filter.velAmount = 0.0;
    rig.play.pitchEnv.enabled = true;
    rig.play.pitchEnv.shape.decayFrames = 24000;
    rig.play.pitchEnv.peakSemitones = 3.0;
@@ -2,10 +2,11 @@
 // test framework.
 //
 // Covers: the chrome band's two rows (toolbar over strip row, tiling the band exactly); the
-// toolbar's fixed right-anchored run in order (preview, velocity cell, curve button,
+// toolbar's fixed right-anchored run in order (preview, velocity cell, Mono|Stereo,
-// Mono|Stereo, Browse) with the title taking the remainder; the velocity knob centred in its
+// Browse) with the title taking the remainder; the velocity knob centred in its
 // cell above its label; the piano strip owning its whole row at every width; no rect on the
-// toolbar overlapping any other; and degenerate bands yielding no inverted rects.
+// toolbar overlapping any other; degenerate bands yielding no inverted rects; and the preview
 // button's play-triangle glyph, which sits inside the button without changing its rect.
 #include "../src/core/instrument/ui/sample_bands.h"
 #include "../src/core/instrument/ui/sample_chrome.h"
@@ -48,20 +49,19 @@ static void testRowsTileTheBandExactly() {
 static void testToolbarRunIsOrderedRightToLeftWithoutOverlap() {
    const Rect band = chromeBand();
    const ChromeRects r = chromeRects(band, kKnob);
-    // Rightmost first: Browse, stereo, mono, curve button, velocity cell, preview, title.
+    // Rightmost first: Browse, stereo, mono, velocity cell, preview, title.
    CHECK(r.navBrowse.right() == band.right() - kPad);
    CHECK(r.navBrowse.width == kNavButtonWidth);
    CHECK(r.chanStereo.right() <= r.navBrowse.x);
    CHECK(r.chanMono.right() == r.chanStereo.x);
-    CHECK(r.curveBtn.right() <= r.chanMono.x);
+    CHECK(r.velCell.right() <= r.chanMono.x);
    CHECK(r.velCell.right() <= r.curveBtn.x);
    CHECK(r.preview.right() <= r.velCell.x);
    CHECK(r.title.right() <= r.preview.x);
    CHECK(r.title.x == band.x + kPad);
    CHECK(r.title.width > 0);
    // Every toolbar rect sits inside the toolbar row.
-    const Rect items[] = {r.title, r.preview, r.velCell, r.curveBtn, r.chanMono,
+    const Rect items[] = {r.title, r.preview, r.velCell, r.chanMono,
                          r.chanStereo, r.navBrowse};
    for (const Rect& it : items) {
        CHECK(it.y >= r.toolbar.y && it.bottom() <= r.toolbar.bottom());
@@ -75,7 +75,7 @@ static void testChromePartsNeverOverlapAtAnyWidth() {
        // stay inside its own row, clear of every control.
        CHECK(!overlaps(r.toolbar, r.rootStrip));
        CHECK(r.rootStrip.y >= r.controls.y && r.rootStrip.bottom() <= r.controls.bottom());
-        const Rect items[] = {r.preview, r.velCell, r.curveBtn, r.chanMono, r.chanStereo,
+        const Rect items[] = {r.preview, r.velCell, r.chanMono, r.chanStereo,
                              r.navBrowse};
        for (const Rect& it : items) {
            CHECK(!overlaps(it, r.rootStrip));
@@ -83,8 +83,8 @@ static void testChromePartsNeverOverlapAtAnyWidth() {
        }
        // The run's own members are pairwise disjoint (velKnob/velLabel are inside velCell,
        // so they are checked against the cell's neighbours, not the cell).
-        for (int i = 0; i < 6; ++i) {
+        for (int i = 0; i < 5; ++i) {
-            for (int j = i + 1; j < 6; ++j) CHECK(!overlaps(items[i], items[j]));
+            for (int j = i + 1; j < 5; ++j) CHECK(!overlaps(items[i], items[j]));
        }
    }
 }
@@ -127,11 +127,38 @@ static void testDegenerateBandYieldsNoInvertedRects() {
    const ChromeRects tiny = chromeRects(Rect::ltrb(0, 0, 40, kTitleHeight + kChromeRowHeight),
                                         kKnob);
    const Rect items[] = {tiny.title, tiny.preview, tiny.velCell, tiny.velKnob, tiny.velLabel,
-                          tiny.curveBtn, tiny.chanMono, tiny.chanStereo, tiny.navBrowse,
+                          tiny.chanMono, tiny.chanStereo, tiny.navBrowse,
                          tiny.rootStrip};
    for (const Rect& it : items) CHECK(it.right() >= it.x && it.bottom() >= it.y);
 }
 static void testPreviewGlyphSitsInsideTheButtonAndPointsRight() {
    const ChromeRects r = chromeRects(chromeBand(), kKnob);
    const PreviewGlyph g = previewGlyph(r.preview);
    CHECK(!g.empty());
    // Wholly inside the button — the glyph replaces the label, it does not resize the target.
    CHECK(g.leftX >= r.preview.x && g.apexX <= r.preview.right());
    CHECK(g.topY >= r.preview.y && g.bottomY <= r.preview.bottom());
    // Right-pointing, and the apex on the button's own centre line so it reads as balanced.
    CHECK(g.apexX > g.leftX);
    CHECK(g.apexY == r.preview.y + r.preview.height / 2);
    CHECK(g.apexY - g.topY == g.bottomY - g.apexY);  // isosceles about the centre line
    // The button's rect is what the hit-test uses, and the glyph must not have moved it: the
    // preview button still sits at the run's fixed size, exactly where the text button did.
    CHECK(r.preview.width == 64 && r.preview.height == 24);
 }
 static void testPreviewGlyphDegradesRatherThanOverflowing() {
    // An unusably small button yields an empty glyph (draw nothing) rather than a triangle
    // spilling past the button edge.
    CHECK(previewGlyph(Rect{}).empty());
    CHECK(previewGlyph(Rect::ltrb(0, 0, 6, 6)).empty());
    // A tall, wide button caps the glyph instead of scaling without bound.
    const PreviewGlyph big = previewGlyph(Rect::ltrb(0, 0, 400, 200));
    CHECK(!big.empty());
    CHECK(big.bottomY - big.topY <= 14);
 }
 static void testToolbarOnlyBandStillPlacesTheNav() {
    // A band clipped to just the toolbar row: the strip row is empty but Browse still
    // resolves, so the empty state's call-to-action is never unreachable.
@@ -149,6 +176,8 @@ int main() {
    testStripOwnsItsWholeRowAndGrowsWithTheWindow();
    testVelocityKnobIsCentredInItsCellAboveTheLabel();
    testDegenerateBandYieldsNoInvertedRects();
    testPreviewGlyphSitsInsideTheButtonAndPointsRight();
    testPreviewGlyphDegradesRatherThanOverflowing();
    testToolbarOnlyBandStillPlacesTheNav();
    if (g_fail == 0) {
@@ -638,7 +638,9 @@ static void testResolvePlayCarriesTheFilterAndResolvesOnlyItsEnvelope() {
    st.filter.settings.driveNorm = 0.125f;
    st.filter.settings.morphLaw = reasampler::instrument::engine::filter::MorphLaw::HighNotchLow;
    st.filter.modAmount = -0.5;
-    st.filter.velAmount = 0.25;
+    st.filter.velAmount = -0.375;  // distinct from every neighbouring field, so a mis-wire shows
    st.filter.velocityCurve = VelocityCurve::fromPoints(
        {{0.0, 0.0}, {127.0, 0.25}}, reasampler::instrument::engine::CurveDomain::Bipolar);
    st.filter.keyTrack = 1.25;
    st.filter.env.attackSeconds = 0.01;
    st.filter.env.holdSeconds = 0.02;
@@ -654,7 +656,12 @@ static void testResolvePlayCarriesTheFilterAndResolvesOnlyItsEnvelope() {
    CHECK(at48.filter.settings.driveNorm == 0.125f);
    CHECK(at48.filter.settings.morphLaw == reasampler::instrument::engine::filter::MorphLaw::HighNotchLow);
    CHECK(at48.filter.modAmount == -0.5);
-    CHECK(at48.filter.velAmount == 0.25);
+    CHECK(at48.filter.velAmount == -0.375);
    // The transfer curve is dimensionless, so it crosses unchanged — asserted against the
    // straight line the two stored knots describe, not against the stored object.
    CHECK(at48.filter.velocityCurve.eval(0.0) == 0.0);
    CHECK(approx(at48.filter.velocityCurve.eval(127.0), 0.25));
    CHECK(approx(at48.filter.velocityCurve.eval(63.5), 0.125));
    CHECK(at48.filter.keyTrack == 1.25);
    CHECK(at48.filter.env.attackFrames == 480);
    CHECK(at48.filter.env.holdFrames == 960);
@@ -673,8 +680,25 @@ static void testResolvePlayCarriesTheFilterAndResolvesOnlyItsEnvelope() {
    CHECK(!bare.filter.enabled);
    CHECK(bare.filter.modAmount == 0.0);
    CHECK(bare.filter.velAmount == 0.0);
    for (int v = 0; v <= 127; ++v) CHECK(bare.filter.velocityCurve.eval(v) == 0.0);
    CHECK(bare.filter.keyTrack == 0.0);
    CHECK(bare.filter.env.sustainLevel == 1.0);
    // The velocity->pitch curve rides the same boundary and is off by the same default.
    for (int v = 0; v <= 127; ++v) CHECK(bare.pitchVelocityCurve.eval(v) == 0.0);
 }
 // The velocity->pitch curve is dimensionless like the filter's, so resolvePlay carries it
 // across the seconds->frames boundary untouched at any rate.
 static void testResolvePlayCarriesThePitchVelocityCurve() {
    PlaySeconds st;
    st.pitchVelocityCurve = VelocityCurve::fromPoints(
        {{0.0, -1.0}, {127.0, 1.0}}, reasampler::instrument::engine::CurveDomain::Bipolar);
    for (const int rate : {44100, 96000}) {
        const PlayParams p = resolvePlay(st, rate);
        CHECK(p.pitchVelocityCurve.eval(0.0) == -1.0);
        CHECK(p.pitchVelocityCurve.eval(127.0) == 1.0);
        CHECK(approx(p.pitchVelocityCurve.eval(63.5), 0.0));
    }
 }
 static void testResolvePlayRoundsAndFloorsNegatives() {
@@ -937,6 +961,7 @@ int main() {
    testLegacyLiftDecision();
    testResolvePlayConvertsWallClockAtTheRate();
    testResolvePlayCarriesTheFilterAndResolvesOnlyItsEnvelope();
    testResolvePlayCarriesThePitchVelocityCurve();
    testResolvePlayRoundsAndFloorsNegatives();
    testMigratedFadeStretchesWhenTheDecodeRateDiffersFromTheProjectRate();
    testResolveCaptureUsesIntrinsicsWhenNoOverride();
@@ -1766,7 +1766,8 @@ static SampleData twoLevelSample() {
    km.velocityCurve = VelocityCurve::fromPoints({{0.0, 0.0},
                                                  {static_cast<double>(kVelLow), 0.25},
                                                  {static_cast<double>(kVelHigh), 0.75},
-                                                  {127.0, 1.0}});
+                                                  {127.0, 1.0}},
                                                 instrument::engine::CurveDomain::Unipolar);
    return km;
 }
@@ -1966,6 +1967,65 @@ static SampleData rampSample(std::size_t frames, int rootNote) {
    return s;
 }
 // --- velocity -> pitch ---------------------------------------------------------
 //
 // A ramp sample reads its own position, so the value on frame N IS the accumulated read rate:
 // the transpose is directly observable rather than inferred from a spectrum.
 static void testVelocityPitchIsExactlyOffByDefault() {
    // The modulation VALUE at every velocity, not a rendered approximation of it: the default
    // bipolar curve must yield the identity ratio exactly, so nothing detunes by a hair.
    const PlayParams def;
    for (int v = 0; v <= 127; ++v) {
        CHECK(velocityPitchRatio(def.pitchVelocityCurve, v) == 1.0);
    }
    // And at the render: two strikes of very different velocity read the ramp identically.
    SampleData s = rampSample(4096, 60);
    Voice soft;
    Voice hard;
    soft.start(60, 1, s);
    hard.start(60, 127, s);
    for (int i = 0; i < 64; ++i) CHECK(soft.renderFrame() == hard.renderFrame());
 }
 static void testDrawnVelocityPitchCurveTransposesBothWays() {
    using instrument::engine::CurveDomain;
    SampleData s = rampSample(4096, 60);
    const double full = std::pow(2.0, kVelocityPitchRangeSemitones / 12.0);
    // A curve pinned at +1 across the domain: every velocity transposes UP by the full scale.
    s.play.pitchVelocityCurve =
        VelocityCurve::fromPoints({{0.0, 1.0}, {127.0, 1.0}}, CurveDomain::Bipolar);
    Voice up;
    up.start(60, 100, s);
    CHECK(approx(static_cast<double>(up.renderFrame()), 0.0, 1e-9));
    CHECK(approx(static_cast<double>(up.renderFrame()), full, 1e-4));
    // Pinned at -1: DOWN by the same scale — the half of the domain the old unipolar curve
    // could not express at all.
    s.play.pitchVelocityCurve =
        VelocityCurve::fromPoints({{0.0, -1.0}, {127.0, -1.0}}, CurveDomain::Bipolar);
    Voice down;
    down.start(60, 100, s);
    down.renderFrame();
    CHECK(approx(static_cast<double>(down.renderFrame()), 1.0 / full, 1e-4));
    // And it follows the curve: a rising ramp gives a soft hit less transpose than a hard one.
    s.play.pitchVelocityCurve =
        VelocityCurve::fromPoints({{0.0, 0.0}, {127.0, 1.0}}, CurveDomain::Bipolar);
    Voice q;
    Voice f;
    q.start(60, 20, s);
    f.start(60, 120, s);
    q.renderFrame();
    f.renderFrame();
    const double quiet = static_cast<double>(q.renderFrame());
    const double loud = static_cast<double>(f.renderFrame());
    CHECK(quiet > 1.0);
    CHECK(loud > quiet);
    CHECK(loud < full);  // velocity 120 is short of the +1 endpoint
 }
 // MAJOR-1 regression: MONO+LEGATO with a TRIGGER zone RE-ATTACKS after the last key is up.
 // Trigger ignores note-off (Voice::release() is a no-op, so releasing_ never latches), so a
 // legato guard keyed on `active && !releasing` saw a ringing one-shot as "still held" and
@@ -2801,6 +2861,8 @@ int main() {
    testRepitchObservedPeriod();
    testKeyTrackVarispeedObservedPeriod();
    testKeyTrackPreserveShiftCollapsesAtZero();
    testVelocityPitchIsExactlyOffByDefault();
    testDrawnVelocityPitchCurveTransposesBothWays();
    testAdsrShape();
    testAdsrReleaseBeforeSustain();
    testAdsrZeroAttackDecay();
@@ -117,6 +117,8 @@ static void testDisengagedFilterIsBitInertEvenWithExtremeSettingsStored() {
    stored.play.filter.settings.driveNorm = 1.0f;
    stored.play.filter.modAmount = 1.0;
    stored.play.filter.velAmount = -1.0;
    stored.play.filter.velocityCurve = VelocityCurve::fromPoints(
        {{0.0, 0.0}, {127.0, -1.0}}, instrument::engine::CurveDomain::Bipolar);
    stored.play.filter.keyTrack = 2.0;
    const std::vector<double> inert = render(stored, 60, 100, 1500);
    for (std::size_t i = 0; i < inert.size(); ++i) CHECK(inert[i] == bare[i]);
@@ -329,40 +331,91 @@ static void testAnUnmodulatedVoiceIsBitIdenticalToASinglePreparedFilter() {
 static void testVelocityAndKeyTrackingReachCutoffAndAreNoOpsAtTheirDefaults() {
    // Playback key-tracking off, so both notes read the source at the SAME rate and the only
    // note-dependent difference left is the filter's own key-tracking.
-    const auto tone = [](double velAmount, double keyTrack) {
+    const auto tone = [](double velAmount, double velTop, double keyTrack) {
        SampleData s = periodicSine(8000, 64);
        s.play.adsr = flatAdsr();
        s.keyTrack = 0.0;
        s.play.filter = engagedFilter(0.25f, 0.0f, 1.0f);
        s.play.filter.velAmount = velAmount;
        if (velTop != 0.0) {
            s.play.filter.velocityCurve = VelocityCurve::fromPoints(
                {{0.0, 0.0}, {127.0, velTop}}, instrument::engine::CurveDomain::Bipolar);
        }
        s.play.filter.keyTrack = keyTrack;
        return s;
    };
-    // Velocity: the default linear curve rises with velocity, so a positive depth opens the
+    // Velocity: a curve rising to +1 at full depth opens the filter for a hard hit. The amp's
-    // filter for a hard hit. The amp's own velocity curve is flat, so amplitude is unaffected.
+    // own velocity curve is flat, so amplitude is unaffected.
-    SampleData vel = tone(1.0, 0.0);
+    SampleData vel = tone(1.0, 1.0, 0.0);
    const std::vector<double> soft = render(vel, 60, 1, 6000);
    const std::vector<double> hard = render(vel, 60, 127, 6000);
    CHECK(rms(hard, 2000, 6000) > 2.0 * rms(soft, 2000, 6000));
    // Key tracking: two octaves up opens it by two octaves of cutoff.
-    SampleData key = tone(0.0, 1.0);
+    SampleData key = tone(0.0, 0.0, 1.0);
    const std::vector<double> low = render(key, 60, 100, 6000);
    const std::vector<double> high = render(key, 84, 100, 6000);
    CHECK(rms(high, 2000, 6000) > 2.0 * rms(low, 2000, 6000));
-    // Both neutral: neither velocity nor note may move the filter.
+    // Both neutral: neither velocity nor note may move the filter. `tone(_,0,0)` leaves the
-    SampleData neutral = tone(0.0, 0.0);
+    // DEFAULT velocity curve, so this is the off-by-default contract itself — and it holds at
-    const std::vector<double> a = render(neutral, 60, 1, 6000);
+    // EVERY depth setting, since the curve is what says "nothing", not the knob.
-    const std::vector<double> b = render(neutral, 60, 127, 6000);
+    for (const double depth : {-1.0, -0.5, 0.0, 0.5, 1.0}) {
-    const std::vector<double> c = render(neutral, 84, 100, 6000);
+        SampleData neutral = tone(depth, 0.0, 0.0);
-    for (std::size_t i = 0; i < a.size(); ++i) {
+        const std::vector<double> a = render(neutral, 60, 1, 6000);
-        CHECK(a[i] == b[i]);
+        const std::vector<double> b = render(neutral, 60, 127, 6000);
-        CHECK(a[i] == c[i]);
+        const std::vector<double> c = render(neutral, 84, 100, 6000);
        for (std::size_t i = 0; i < a.size(); ++i) {
            CHECK(a[i] == b[i]);
            CHECK(a[i] == c[i]);
        }
        // And the modulation VALUE itself is exactly zero at every velocity, not merely small
        // enough that the render came out equal — the render check alone would still pass
        // under a cutoff offset too small to survive the coefficient solve's float rounding.
        const FilterParams def;
        for (int v = 0; v <= 127; ++v) CHECK(depth * def.velocityCurve.eval(v) == 0.0);
    }
 }
 // The depth knob and the bipolar curve BOTH apply, as a product: flipping the depth's sign is
 // the same modulation as flipping the curve's, and it flips the audible sense with it.
 static void testFilterVelocityDepthAndCurveComposeMultiplicatively() {
    using instrument::engine::CurveDomain;
    using instrument::engine::VelocityPoint;
    const std::vector<VelocityPoint> rising = {{0.0, 0.0}, {64.0, 0.4}, {127.0, 1.0}};
    std::vector<VelocityPoint> mirrored = rising;
    for (VelocityPoint& p : mirrored) p.value = -p.value;
    const auto rig = [](double depth, const std::vector<VelocityPoint>& pts) {
        SampleData s = periodicSine(8000, 64);
        s.play.adsr = flatAdsr();
        s.keyTrack = 0.0;
        s.play.filter = engagedFilter(0.25f, 0.0f, 1.0f);
        s.play.filter.velAmount = depth;
        s.play.filter.velocityCurve = VelocityCurve::fromPoints(pts, CurveDomain::Bipolar);
        return s;
    };
    // A negative depth over a rising curve is the SAME cutoff offset as a positive depth over
    // the curve's mirror — frame for frame, not approximately.
    SampleData byDepth = rig(-0.75, rising);
    SampleData byCurve = rig(0.75, mirrored);
    const std::vector<double> viaDepth = render(byDepth, 60, 120, 6000);
    const std::vector<double> viaCurve = render(byCurve, 60, 120, 6000);
    for (std::size_t i = 0; i < viaDepth.size(); ++i) CHECK(viaDepth[i] == viaCurve[i]);
    // And the sense really inverts: over the same rising curve a positive depth opens the
    // filter for a hard hit while the negative one closes it.
    SampleData up = rig(0.75, rising);
    const std::vector<double> upSoft = render(up, 60, 1, 6000);
    const std::vector<double> upHard = render(up, 60, 120, 6000);
    CHECK(rms(upHard, 2000, 6000) > 2.0 * rms(upSoft, 2000, 6000));
    const std::vector<double> downSoft = render(byDepth, 60, 1, 6000);
    const std::vector<double> downHard = render(byDepth, 60, 120, 6000);
    CHECK(rms(downSoft, 2000, 6000) > 2.0 * rms(downHard, 2000, 6000));
 }
 static void testNoteOnResetsTheFilterSoAPreviousNoteCannotLeak() {
    SampleData s = periodicSine(8000, 64);
    s.play.adsr = flatAdsr();
@@ -432,6 +485,7 @@ int main() {
    testAModulationTooSmallToCrossTheRetiredQuantumStillMovesTheVoice();
    testAnUnmodulatedVoiceIsBitIdenticalToASinglePreparedFilter();
    testVelocityAndKeyTrackingReachCutoffAndAreNoOpsAtTheirDefaults();
    testFilterVelocityDepthAndCurveComposeMultiplicatively();
    testNoteOnResetsTheFilterSoAPreviousNoteCannotLeak();
    testStereoRenderOfAMonoSampleMirrorsTheMonoResultExactly();
    testStereoFilterChannel1MatchesChannel0ForIdenticalLRInput();
@@ -1,20 +1,24 @@
 // Standalone tests for reasampler::instrument::engine::velocity_curve — no VST3, no REAPER, no framework. Same fast
-// assert loop as the sibling pure tests. Assert the S-VIEW-9 velocity->amp transfer curve HARD:
+// assert loop as the sibling pure tests. Assert the velocity transfer curve HARD:
 //
-//  * eval — flat y=1 default (R10-F1 Option A: EVERY velocity -> 1.0), linear ramp, curved shape
+//  * eval — flat y=1 unipolar default (EVERY velocity -> 1.0), linear ramp, curved shape
 //    between points, box-clamp of an out-of-range velocity, monotonic-in-x over the whole domain.
 //  * the BIPOLAR domain — zero() is exactly 0 everywhere, the negative half evaluates and clamps
 //    at -1, knots inside [0,1] evaluate identically in either domain (what the codec's v12
 //    re-tag rests on), and the pixel maps put value 0 on the box's centre line, not its floor.
 //  * editing — addPoint keeps X-order + box-clamp; movePoint clamps an interior point between its
-//    neighbours (can't cross) and box-clamps amp; endpoints are X-pinned (velocity 0 / 127) with
+//    neighbours (can't cross) and box-clamps the value; endpoints are X-pinned (velocity 0 / 127)
-//    only amp mobile; deletePoint removes interior points but REFUSES the two endpoints.
+//    with only the value mobile; deletePoint removes interior points but REFUSES the two endpoints.
 //  * hit-test + inverse map — pointAtPixel grabs a drawn node; resolvePointDrag maps pixel delta to
 //    a clamped point (endpoint X-pinned; interior clamped to neighbours); degenerate box -> no motion.
 //  * fromPoints — the deserialization repair: sorts by X, box-clamps, forces endpoints, and falls
-//    back to flat() for a sub-2-point list.
+//    back to each domain's OWN neutral for a sub-2-point list.
 #include "../src/core/instrument/engine/velocity_curve.h"
 #include <cmath>
 #include <cstdio>
 #include <vector>
 using namespace reasampler;
 using namespace reasampler::instrument::engine;
@@ -27,6 +31,17 @@ static bool near(double a, double b, double eps = 1e-9) { return std::fabs(a - b
 using Box = VelocityCurve::Box;
 // The pixel maps are members (the y domain lives on the curve), so a mapping test speaks
 // through a curve of the domain under test rather than a free function.
 static const VelocityCurve& uni() {
    static const VelocityCurve c = VelocityCurve::flat();
    return c;
 }
 static const VelocityCurve& bip() {
    static const VelocityCurve c = VelocityCurve::zero();
    return c;
 }
 // --- eval ---------------------------------------------------------------------
 static void testFlatIsUnityEverywhere() {
@@ -151,11 +166,11 @@ static void testAddPointKeepsXOrderAndClamps() {
    const std::size_t i = c.addPoint(60.0, 0.3);
    CHECK(i == 1);  // inserted between the two endpoints
    CHECK(c.size() == 3);
-    CHECK(near(c.points()[1].velocity, 60.0) && near(c.points()[1].amp, 0.3));
+    CHECK(near(c.points()[1].velocity, 60.0) && near(c.points()[1].value, 0.3));
    // Out-of-box add clamps into [0,127] x [0,1].
    c.addPoint(500.0, 5.0);
    const VelocityPoint& last = c.points().back();
-    CHECK(near(last.velocity, 127.0) && near(last.amp, 1.0));
+    CHECK(near(last.velocity, 127.0) && near(last.value, 1.0));
    // Points remain X-ordered.
    for (std::size_t k = 1; k < c.size(); ++k)
        CHECK(c.points()[k - 1].velocity <= c.points()[k].velocity);
@@ -171,7 +186,7 @@ static void testMoveInteriorClampsToNeighbours() {
    // Try to drag idx 1 PAST idx 2 (velocity 200): clamps to idx 2's velocity (80), not beyond.
    const VelocityPoint r = c.movePoint(1, 200.0, 0.5);
    CHECK(near(r.velocity, 80.0));
-    CHECK(near(r.amp, 0.5));  // amp is free (box-clamped only)
+    CHECK(near(r.value, 0.5));  // amp is free (box-clamped only)
    // Try to drag idx 1 BELOW idx 0 (velocity -5): clamps to idx 0's velocity (0).
    const VelocityPoint r2 = c.movePoint(1, -5.0, 0.5);
    CHECK(near(r2.velocity, 0.0));
@@ -182,18 +197,18 @@ static void testMoveEndpointsArePinnedInX() {
    // Move the first endpoint: velocity argument ignored (pinned at 0), amp moves.
    const VelocityPoint f = c.movePoint(0, 50.0, 0.25);
    CHECK(near(f.velocity, 0.0));
-    CHECK(near(f.amp, 0.25));
+    CHECK(near(f.value, 0.25));
    // Move the last endpoint: pinned at 127, amp moves, and amp box-clamps.
    const VelocityPoint l = c.movePoint(1, 10.0, 5.0);
    CHECK(near(l.velocity, 127.0));
-    CHECK(near(l.amp, 1.0));
+    CHECK(near(l.value, 1.0));
 }
 static void testMoveOutOfRangeIndexIsNoOp() {
    VelocityCurve c = VelocityCurve::linear();
    c.movePoint(99, 50.0, 0.5);
    CHECK(c.size() == 2);
-    CHECK(near(c.points()[0].amp, 0.0) && near(c.points()[1].amp, 1.0));  // unchanged
+    CHECK(near(c.points()[0].value, 0.0) && near(c.points()[1].value, 1.0));  // unchanged
 }
 // --- editing: deletePoint -----------------------------------------------------
@@ -237,11 +252,11 @@ static void testResolveDragMovesAndClamps() {
    // Drag idx 1 right 10px, up 10px: velocity +10 (->70), amp +0.10 (up = higher amp -> 0.60).
    const VelocityCurve moved = VelocityCurve::resolvePointDrag(grab, 1, b, 10, -10);
    CHECK(near(moved.points()[1].velocity, 70.0, 1e-6));
-    CHECK(near(moved.points()[1].amp, 0.60, 1e-6));
+    CHECK(near(moved.points()[1].value, 0.60, 1e-6));
    // Dragging the first endpoint horizontally does not move it in X (pinned), only amp.
    const VelocityCurve movedEnd = VelocityCurve::resolvePointDrag(grab, 0, b, 40, -20);
    CHECK(near(movedEnd.points()[0].velocity, 0.0));
-    CHECK(near(movedEnd.points()[0].amp, 0.20, 1e-6));  // dragged up 20px = +0.20 from 0
+    CHECK(near(movedEnd.points()[0].value, 0.20, 1e-6));  // dragged up 20px = +0.20 from 0
 }
 static void testResolveDragDegenerateBoxNoMotion() {
@@ -255,7 +270,7 @@ static void testResolveDragDegenerateBoxNoMotion() {
 static void testFromPointsSortsClampsAndForcesEndpoints() {
    // Unsorted, out-of-box, missing endpoints -> repaired to a valid curve.
    std::vector<VelocityPoint> raw = {{80.0, 0.9}, {20.0, -1.0}, {50.0, 2.0}};
-    const VelocityCurve c = VelocityCurve::fromPoints(raw);
+    const VelocityCurve c = VelocityCurve::fromPoints(raw, CurveDomain::Unipolar);
    // X-ordered.
    for (std::size_t k = 1; k < c.size(); ++k)
        CHECK(c.points()[k - 1].velocity <= c.points()[k].velocity);
@@ -264,15 +279,98 @@ static void testFromPointsSortsClampsAndForcesEndpoints() {
    CHECK(near(c.points().back().velocity, 127.0));
    // Interior amps box-clamped (the -1 became 0, the 2 became 1).
    for (const VelocityPoint& p : c.points()) {
-        CHECK(p.amp >= 0.0 - 1e-12 && p.amp <= 1.0 + 1e-12);
+        CHECK(p.value >= 0.0 - 1e-12 && p.value <= 1.0 + 1e-12);
    }
 }
 static void testFromPointsSubTwoFallsBackToFlat() {
-    const VelocityCurve c0 = VelocityCurve::fromPoints({});
+    const VelocityCurve c0 = VelocityCurve::fromPoints({}, CurveDomain::Unipolar);
    CHECK(c0.equals(VelocityCurve::flat()));
-    const VelocityCurve c1 = VelocityCurve::fromPoints({{50.0, 0.3}});
+    const VelocityCurve c1 = VelocityCurve::fromPoints({{50.0, 0.3}}, CurveDomain::Unipolar);
    CHECK(c1.equals(VelocityCurve::flat()));
    // The bipolar fallback is the domain's OWN neutral, not the unipolar one: degrading a
    // corrupt pitch/filter curve to flat-at-unity would transpose or open the filter fully.
    const VelocityCurve b0 = VelocityCurve::fromPoints({}, CurveDomain::Bipolar);
    CHECK(b0.equals(VelocityCurve::zero()));
    const VelocityCurve b1 = VelocityCurve::fromPoints({{50.0, 0.3}}, CurveDomain::Bipolar);
    CHECK(b1.equals(VelocityCurve::zero()));
 }
 // --- the bipolar domain -------------------------------------------------------
 static void testZeroIsExactlyZeroAtEveryVelocity() {
    // The off-by-default contract: not "approximately zero" — EXACTLY zero, so a pitch or
    // cutoff offset derived from it cannot nudge anything.
    const VelocityCurve c = VelocityCurve::zero();
    CHECK(c.domain() == CurveDomain::Bipolar);
    for (int v = -20; v <= 200; ++v) CHECK(c.eval(v) == 0.0);
    CHECK(c.size() == 2);
 }
 static void testBipolarEvalSpansTheNegativeHalf() {
    // A ramp from -1 at velocity 0 to +1 at 127: collinear knots, so the spline is the exact
    // straight line through zero — the whole point of the widened domain.
    const VelocityCurve c =
        VelocityCurve::fromPoints({{0.0, -1.0}, {127.0, 1.0}}, CurveDomain::Bipolar);
    CHECK(near(c.eval(0), -1.0));
    CHECK(near(c.eval(127), 1.0));
    CHECK(near(c.eval(63.5), 0.0, 1e-12));
    for (int v = 0; v <= 127; ++v) CHECK(near(c.eval(v), 2.0 * v / 127.0 - 1.0, 1e-12));
 }
 static void testUnipolarClampsAtZeroWhereBipolarDoesNot() {
    // The same negative knot, read in the two domains: unipolar floors it at 0 (an amp gain
    // cannot be negative), bipolar keeps it.
    const std::vector<VelocityPoint> raw = {{0.0, -0.5}, {127.0, 0.5}};
    const VelocityCurve u = VelocityCurve::fromPoints(raw, CurveDomain::Unipolar);
    const VelocityCurve b = VelocityCurve::fromPoints(raw, CurveDomain::Bipolar);
    CHECK(near(u.eval(0), 0.0));
    CHECK(near(b.eval(0), -0.5));
    // Out-of-domain magnitudes clamp to each domain's own floor.
    const VelocityCurve b2 =
        VelocityCurve::fromPoints({{0.0, -9.0}, {127.0, 9.0}}, CurveDomain::Bipolar);
    CHECK(near(b2.eval(0), -1.0));
    CHECK(near(b2.eval(127), 1.0));
 }
 static void testTheSameKnotsEvaluateIdenticallyInEitherDomain() {
    // What the codec's v12 domain re-tag rests on: a curve whose y values all lie in [0,1] is
    // read the same way in either domain — the domain governs the CLAMP, not the evaluation.
    // Asserted against a CURVED (non-collinear) knot set, where the tangents are doing work,
    // and with ==: the re-tag is bit-identical, not merely close.
    const std::vector<VelocityPoint> knots = {
        {0.0, 0.1}, {30.0, 0.15}, {64.0, 0.9}, {100.0, 0.4}, {127.0, 1.0}};
    const VelocityCurve u = VelocityCurve::fromPoints(knots, CurveDomain::Unipolar);
    const VelocityCurve b = VelocityCurve::fromPoints(knots, CurveDomain::Bipolar);
    for (int v = 0; v <= 127; ++v) CHECK(b.eval(v) == u.eval(v));
 }
 static void testBipolarPixelMapPutsZeroOnTheCentreLine() {
    // The same box, read in the two domains: value 0 sits at the vertical centre for a bipolar
    // curve and at the bottom row for a unipolar one — the one mapping difference the shared
    // popup code path has to get right.
    const Box box{10, 20, 100, 101};   // 100 value rows: centre is 50 rows down
    CHECK(bip().pixelFromPoint(box, {0.0, 0.0}).y == 70);
    CHECK(uni().pixelFromPoint(box, {0.0, 0.0}).y == 120);
    // Each domain's floor lands on the bottom row, its ceiling on the top.
    CHECK(bip().pixelFromPoint(box, {0.0, -1.0}).y == 120);
    CHECK(bip().pixelFromPoint(box, {0.0, 1.0}).y == 20);
    // And the inverse agrees: the centre row reads back as 0 in bipolar, mid-scale in unipolar.
    CHECK(near(bip().pointFromPixel(box, 10, 70).value, 0.0, 1e-12));
    CHECK(near(uni().pointFromPixel(box, 10, 70).value, 0.5, 1e-12));
 }
 static void testBipolarDragCoversTwiceTheValueRange() {
    // A drag of N pixels moves twice as much value in bipolar as in unipolar over the same box
    // — the domain spans 2.0, not 1.0. Both still land inside their own domain.
    const Box box{0, 0, 127, 101};  // 100 value rows
    VelocityCurve u = VelocityCurve::flat();
    u.movePoint(0, 0.0, 0.5);
    VelocityCurve b = VelocityCurve::zero();
    const VelocityCurve uMoved = VelocityCurve::resolvePointDrag(u, 0, box, 0, -10);
    const VelocityCurve bMoved = VelocityCurve::resolvePointDrag(b, 0, box, 0, -10);
    CHECK(near(uMoved.points()[0].value, 0.60, 1e-6));
    CHECK(near(bMoved.points()[0].value, 0.20, 1e-6));
 }
 // --- S-VIEW-10 pixel maps (the editor draw/add seam) -----------------------------
@@ -282,29 +380,29 @@ static void testPixelFromPointMapsCornersAndMidpoint() {
    // (h - 1) rows with amp 1 at the top — assert the drawn corners land where the module's own
    // hit-test mapping puts them.
    const Box box{10, 20, 100, 51};
-    const auto tl = VelocityCurve::pixelFromPoint(box, {0.0, 1.0});
+    const auto tl = uni().pixelFromPoint(box, {0.0, 1.0});
    CHECK(tl.x == 10 && tl.y == 20);
-    const auto br = VelocityCurve::pixelFromPoint(box, {127.0, 0.0});
+    const auto br = uni().pixelFromPoint(box, {127.0, 0.0});
    CHECK(br.x == 110 && br.y == 70);
-    const auto mid = VelocityCurve::pixelFromPoint(box, {63.5, 0.5});
+    const auto mid = uni().pixelFromPoint(box, {63.5, 0.5});
    CHECK(mid.x == 60 && mid.y == 45);
    // Out-of-box values are clamped by the mapping (velocity 200 draws at the right edge).
-    const auto clamped = VelocityCurve::pixelFromPoint(box, {200.0, 2.0});
+    const auto clamped = uni().pixelFromPoint(box, {200.0, 2.0});
    CHECK(clamped.x == 110 && clamped.y == 20);
 }
 static void testPointFromPixelInvertsAndClamps() {
    const Box box{10, 20, 100, 51};
    // Exact corners invert exactly.
-    const VelocityPoint tl = VelocityCurve::pointFromPixel(box, 10, 20);
+    const VelocityPoint tl = uni().pointFromPixel(box, 10, 20);
-    CHECK(near(tl.velocity, 0.0) && near(tl.amp, 1.0));
+    CHECK(near(tl.velocity, 0.0) && near(tl.value, 1.0));
-    const VelocityPoint br = VelocityCurve::pointFromPixel(box, 110, 70);
+    const VelocityPoint br = uni().pointFromPixel(box, 110, 70);
-    CHECK(near(br.velocity, 127.0) && near(br.amp, 0.0));
+    CHECK(near(br.velocity, 127.0) && near(br.value, 0.0));
    // A pixel OUTSIDE the box clamps into the domain (never an invariant-violating point).
-    const VelocityPoint out = VelocityCurve::pointFromPixel(box, -50, 500);
+    const VelocityPoint out = uni().pointFromPixel(box, -50, 500);
-    CHECK(near(out.velocity, 0.0) && near(out.amp, 0.0));
+    CHECK(near(out.velocity, 0.0) && near(out.value, 0.0));
-    const VelocityPoint out2 = VelocityCurve::pointFromPixel(box, 500, -50);
+    const VelocityPoint out2 = uni().pointFromPixel(box, 500, -50);
-    CHECK(near(out2.velocity, 127.0) && near(out2.amp, 1.0));
+    CHECK(near(out2.velocity, 127.0) && near(out2.value, 1.0));
 }
 static void testPixelMapsRoundTripWithinOnePixelQuantum() {
@@ -315,10 +413,10 @@ static void testPixelMapsRoundTripWithinOnePixelQuantum() {
    const double ampQuantum = 1.0 / 119.0;
    const VelocityPoint pts[] = {{0.0, 1.0}, {127.0, 0.0}, {40.0, 0.25}, {90.5, 0.66}, {63.5, 0.5}};
    for (const VelocityPoint& p : pts) {
-        const auto px = VelocityCurve::pixelFromPoint(box, p);
+        const auto px = uni().pixelFromPoint(box, p);
-        const VelocityPoint back = VelocityCurve::pointFromPixel(box, px.x, px.y);
+        const VelocityPoint back = uni().pointFromPixel(box, px.x, px.y);
        CHECK(std::fabs(back.velocity - p.velocity) <= velQuantum);
-        CHECK(std::fabs(back.amp - p.amp) <= ampQuantum);
+        CHECK(std::fabs(back.value - p.value) <= ampQuantum);
    }
 }
@@ -328,15 +426,15 @@ static void testPixelFromPointAgreesWithPointAtPixel() {
    VelocityCurve c = VelocityCurve::linear();
    const std::size_t idx = c.addPoint(70.0, 0.3);
    const Box box{0, 0, 200, 100};
-    const auto px = VelocityCurve::pixelFromPoint(box, c.points()[idx]);
+    const auto px = uni().pixelFromPoint(box, c.points()[idx]);
    CHECK(c.pointAtPixel(box, px.x, px.y) == static_cast<int>(idx));
 }
 static void testPointFromPixelDegenerateBox() {
    // Zero width -> velocity 0; height <= 1 -> amp 1 (mirrors the forward map's degenerate pins).
    const Box flat{5, 5, 0, 0};
-    const VelocityPoint p = VelocityCurve::pointFromPixel(flat, 50, 50);
+    const VelocityPoint p = uni().pointFromPixel(flat, 50, 50);
-    CHECK(near(p.velocity, 0.0) && near(p.amp, 1.0));
+    CHECK(near(p.velocity, 0.0) && near(p.value, 1.0));
 }
 static void testFromPointsRoundTripsAValidCurve() {
@@ -344,7 +442,7 @@ static void testFromPointsRoundTripsAValidCurve() {
    orig.addPoint(40.0, 0.2);
    orig.addPoint(90.0, 0.7);
    // fromPoints over its OWN points reproduces it exactly (already valid, sort is stable no-op).
-    const VelocityCurve rebuilt = VelocityCurve::fromPoints(orig.points());
+    const VelocityCurve rebuilt = VelocityCurve::fromPoints(orig.points(), CurveDomain::Unipolar);
    CHECK(rebuilt.equals(orig));
 }
@@ -367,6 +465,12 @@ int main() {
    testResolveDragDegenerateBoxNoMotion();
    testFromPointsSortsClampsAndForcesEndpoints();
    testFromPointsSubTwoFallsBackToFlat();
    testZeroIsExactlyZeroAtEveryVelocity();
    testBipolarEvalSpansTheNegativeHalf();
    testUnipolarClampsAtZeroWhereBipolarDoesNot();
    testTheSameKnotsEvaluateIdenticallyInEitherDomain();
    testBipolarPixelMapPutsZeroOnTheCentreLine();
    testBipolarDragCoversTwiceTheValueRange();
    testPixelFromPointMapsCornersAndMidpoint();
    testPointFromPixelInvertsAndClamps();
    testPixelMapsRoundTripWithinOnePixelQuantum();