FA2: bounded-schematic Gate envelope (15% sustain reserve, in-bounds release) + zero-fade-out grabbable via nearest-node hit-test; all nodes clamp in-canvas

src/vst/envelope_edit.cpp

@@ -23,6 +23,15 @@ double secondsPerPixel(const Rect& area, double totalSeconds) {
     return totalSeconds / static_cast<double>(w);
 }
 
+// Seconds per pixel in the GATE timed region (FA2): the Gate schematic maps A/H/D/R onto
+// gateTimedWidth(area) px, not the full canvas, so a Gate time-node drag must use this scale for
+// the handle to track the cursor. Matches envelope_overlay::gatePolyline.
+double gateSecondsPerPixel(const Rect& area, double totalSeconds) {
+    const int w = gateTimedWidth(area);
+    if (w <= 0 || totalSeconds <= 0.0) return 0.0;
+    return totalSeconds / static_cast<double>(w);
+}
+
 // Level (0..1) represented by one vertical pixel. levelToY spans (height-1) rows for [0,1], so one
 // pixel is 1/(height-1). Zero when degenerate. Matches envelope_overlay::levelToY.
 double levelPerPixel(const Rect& area) {
@@ -46,14 +55,23 @@ bool isDraggable(EnvNode n) {
 
 NodeHit nodeAtPoint(const AmpEnvelope& env, const Rect& area, double totalSeconds, int x, int y) {
     const std::vector<EnvVertex> poly = buildEnvelopePolyline(env, area, totalSeconds);
-    // First-match in draw order (deterministic tie-break), skipping non-draggable anchors.
+    // NEAREST draggable node within the pick radius wins (Chebyshev distance — the square grab
+    // box); ties break to the earlier draw-order node (FA2). Nearest-wins keeps every handle
+    // grabbable when nodes sit close (e.g. a short hold), while the draw-order tie-break makes
+    // exactly-coincident nodes deterministic: at zero fade-out, FadeOutStart overlays LengthEnd
+    // and WINS the tie, so the fade-out handle is grabbable at the right edge and can be dragged
+    // inward from zero.
+    NodeHit best;
+    int bestDist = kNodeGrabRadius + 1;
     for (const EnvVertex& v : poly) {
         if (!isDraggable(v.node)) continue;
-        if (std::abs(x - v.x) <= kNodeGrabRadius && std::abs(y - v.y) <= kNodeGrabRadius) {
-            return NodeHit{true, v.node};
+        const int dist = std::max(std::abs(x - v.x), std::abs(y - v.y));
+        if (dist < bestDist) {  // strictly closer only: earlier draw order keeps ties
+            bestDist = dist;
+            best = NodeHit{true, v.node};
         }
     }
-    return NodeHit{false, EnvNode::Origin};
+    return best;
 }
 
 AmpEnvelope resolveNodeDrag(const AmpEnvelope& grabEnv, EnvNode node, const Rect& area,
@@ -65,21 +83,28 @@ AmpEnvelope resolveNodeDrag(const AmpEnvelope& grabEnv, EnvNode node, const Rect
     const double secPerPx = secondsPerPixel(area, totalSeconds);
     if (secPerPx <= 0.0) return out;  // degenerate area / duration — no motion
     const double dSec = static_cast<double>(dxPixels) * secPerPx;
+    // Gate time nodes live in the TIMED region of the Gate schematic (FA2), which is narrower
+    // than the canvas by the sustain-plateau reserve — their px->seconds scale differs so the
+    // dragged handle tracks the cursor 1:1. gateTimedWidth >= 1 whenever the area is non-empty,
+    // so gateDSec is well-defined past the degenerate guard above.
+    const double gateDSec =
+        static_cast<double>(dxPixels) * gateSecondsPerPixel(area, totalSeconds);
 
     switch (node) {
         // --- Gate: each cumulative-time node edits its OWN segment duration. Non-negative
         //     durations ARE the monotonic-in-time guarantee (a node can never cross a neighbour
         //     because every segment stays >= 0), so the [0, max] clamp is the whole constraint.
         case EnvNode::AttackEnd:
-            out.attackSeconds = clamp(grabEnv.attackSeconds + dSec, 0.0, bounds.maxAttackSeconds);
+            out.attackSeconds =
+                clamp(grabEnv.attackSeconds + gateDSec, 0.0, bounds.maxAttackSeconds);
             break;
         case EnvNode::HoldEnd:
-            out.holdSeconds = clamp(grabEnv.holdSeconds + dSec, 0.0, bounds.maxHoldSeconds);
+            out.holdSeconds = clamp(grabEnv.holdSeconds + gateDSec, 0.0, bounds.maxHoldSeconds);
             break;
         case EnvNode::DecayEnd: {
             // Sustain node: X sets decay time, Y sets sustain level (drag DOWN = higher y = lower
             // level, so subtract the level delta).
-            out.decaySeconds = clamp(grabEnv.decaySeconds + dSec, 0.0, bounds.maxDecaySeconds);
+            out.decaySeconds = clamp(grabEnv.decaySeconds + gateDSec, 0.0, bounds.maxDecaySeconds);
             const double lvlPerPx = levelPerPixel(area);
             const double dLevel = -static_cast<double>(dyPixels) * lvlPerPx;
             out.sustainLevel = clamp(grabEnv.sustainLevel + dLevel, 0.0, 1.0);
@@ -87,7 +112,7 @@ AmpEnvelope resolveNodeDrag(const AmpEnvelope& grabEnv, EnvNode node, const Rect
         }
         case EnvNode::ReleaseEnd:
             out.releaseSeconds =
-                clamp(grabEnv.releaseSeconds + dSec, 0.0, bounds.maxReleaseSeconds);
+                clamp(grabEnv.releaseSeconds + gateDSec, 0.0, bounds.maxReleaseSeconds);
             break;
 
         // --- Trigger: fades + length are FRACTIONS. X pixels convert to a fraction of the PLAYED

src/vst/envelope_edit.h

@@ -20,11 +20,16 @@
 //     CALLER-SUPPLIED here (EnvClampBounds): the shell passes the same maxima it feeds the slider,
 //     so the two surfaces share one clamp by construction.
 //
-// WHICH AXES. Time-only nodes (attack-end, hold-end, release-end; fade-in-end, length-end,
-// fade-out-end) drag on X only. The sustain node (DecayEnd) drags on BOTH axes — its X sets the
+// WHICH AXES. Time-only nodes (AttackEnd, HoldEnd, ReleaseEnd; FadeInEnd, FadeOutStart,
+// LengthEnd) drag on X only. The sustain node (DecayEnd) drags on BOTH axes — its X sets the
 // decay time, its Y sets the sustain level (the standard ADSR-editor grammar). Origin and the
 // drawing-only ReleaseStart vertex are NOT draggable.
 //
+// GATE DRAG SCALE (FA2). Gate time nodes live in the Gate schematic's TIMED region
+// (gateTimedWidth(area) px — the canvas minus the sustain-plateau reserve), so their px->seconds
+// conversion uses that width, not the full canvas; Trigger nodes keep the full-canvas scale.
+// Both match the forward map in envelope_overlay, so a dragged handle tracks the cursor 1:1.
+//
 // Reuses editor_geometry's Rect + the EnvNode / AmpEnvelope / EnvMode types from
 // envelope_overlay (one shared node vocabulary across draw + edit), and the shared timeToX /
 // levelToY maps so the handle the overlay drew and the grab region here agree pixel-for-pixel.
@@ -64,9 +69,11 @@ struct EnvClampBounds {
 // Which node a grab at (x, y) lands on, given the CURRENT envelope + overlay rect + sample
 // duration (the same inputs buildEnvelopePolyline drew from, so the grab tests the drawn handles).
 // Returns EnvNode::Origin's NON-membership as a miss via the bool return: `hit` is false for a
-// point off every DRAGGABLE node. Origin and ReleaseStart are never returned (not draggable). On a
-// tie (two handles within the radius) the earlier draw-order node wins (deterministic, mirroring
-// waveform_view::markerAtPoint's first-match). Pure.
+// point off every DRAGGABLE node. Origin and ReleaseStart are never returned (not draggable).
+// The NEAREST node within the radius wins (Chebyshev distance); an exact tie goes to the earlier
+// draw-order node (FA2 — deterministic, and it makes coincident nodes grabbable: at zero
+// fade-out, FadeOutStart overlays LengthEnd, wins the tie, and can be dragged inward from the
+// right edge; at zero hold, AttackEnd wins over HoldEnd). Pure.
 struct NodeHit {
     bool    hit  = false;
     EnvNode node = EnvNode::Origin;  // meaningful only when hit == true

src/vst/envelope_overlay.cpp

@@ -10,13 +10,22 @@ int timeToX(const Rect& area, double totalSeconds, double t) {
     const int w = std::max(0, area.width());
     if (w <= 0 || totalSeconds <= 0.0) return area.left;
     if (t < 0.0) t = 0.0;
-    // Linear map, NOT clamped on the high side: t past totalSeconds maps past area.right (the Gate
-    // release tail, drawn after the sample end by design). Round to the nearest pixel.
+    // Linear map, clamped on BOTH sides (FA2 bounds invariant): t past totalSeconds pins to the
+    // last in-bounds column area.right-1. Round to the nearest pixel.
     const double frac = t / totalSeconds;
-    const long xi = static_cast<long>(frac * static_cast<double>(w) + 0.5);
+    long xi = static_cast<long>(frac * static_cast<double>(w) + 0.5);
+    if (xi > w - 1) xi = w - 1;
     return area.left + static_cast<int>(xi);
 }
 
+int gateTimedWidth(const Rect& area) {
+    const int w = std::max(0, area.width());
+    if (w <= 0) return 0;
+    const int sustainPx =
+        static_cast<int>(kGateSustainDisplayFraction * static_cast<double>(w) + 0.5);
+    return std::max(1, w - sustainPx);
+}
+
 int levelToY(const Rect& area, double level) {
     const int h = std::max(0, area.height());
     if (h <= 0) return area.top;
@@ -46,6 +55,22 @@ EnvVertex vtx(EnvNode node, const Rect& area, double totalSeconds, double t, dou
     return v;
 }
 
+// One Gate vertex from a pixel offset inside the area (the Gate schematic works in px space —
+// timed px + the fixed sustain-plateau reserve — not through the plain timeToX map). Clamps x to
+// the last in-bounds column (FA2 bounds invariant).
+EnvVertex gateVtx(EnvNode node, const Rect& area, double px, double level) {
+    const int w = std::max(1, area.width());
+    long xi = static_cast<long>(px + 0.5);
+    if (xi < 0) xi = 0;
+    if (xi > w - 1) xi = w - 1;
+    EnvVertex v;
+    v.node = node;
+    v.x = area.left + static_cast<int>(xi);
+    v.y = levelToY(area, level);
+    v.level = level;
+    return v;
+}
+
 std::vector<EnvVertex> gatePolyline(const AmpEnvelope& env, const Rect& area, double totalSeconds) {
     // Non-negative segment durations (a stored negative would be an upstream bug; clamp defensively).
     const double a = std::max(0.0, env.attackSeconds);
@@ -54,23 +79,27 @@ std::vector<EnvVertex> gatePolyline(const AmpEnvelope& env, const Rect& area, do
     const double r = std::max(0.0, env.releaseSeconds);
     const double sus = clamp01(env.sustainLevel);
 
-    // Cumulative wall-clock times of each breakpoint from t=0.
-    const double tAttack = a;
-    const double tHold   = tAttack + h;
-    const double tDecay  = tHold + d;
-    // The sustain plateau runs to the sample end; if the pre-sustain stages already overrun the
-    // sample, the plateau collapses to zero width (its end clamps up to tDecay).
-    const double tSustainEnd = std::max(tDecay, totalSeconds);
-    const double tRelease    = tSustainEnd + r;  // release trails PAST the sample end, by design
+    // BOUNDED SCHEMATIC (FA2): A/H/D and R map onto the TIMED region (canvas minus the reserved
+    // sustain-plateau width) at the sample's time scale; the sustain plateau is the fixed reserve
+    // between DecayEnd and ReleaseStart. Cumulative px, clamped in gateVtx, stay monotonic.
+    const int timedW    = gateTimedWidth(area);
+    const int sustainPx = std::max(0, area.width()) - timedW;
+    const double pxPerSec = static_cast<double>(timedW) / totalSeconds;
+
+    const double pxAttack  = a * pxPerSec;
+    const double pxHold    = (a + h) * pxPerSec;
+    const double pxDecay   = (a + h + d) * pxPerSec;
+    const double pxPlateau = pxDecay + static_cast<double>(sustainPx);  // schematic note-off
+    const double pxRelease = pxPlateau + r * pxPerSec;
 
     std::vector<EnvVertex> pts;
     pts.reserve(6);
-    pts.push_back(vtx(EnvNode::Origin,       area, totalSeconds, 0.0,         0.0));
-    pts.push_back(vtx(EnvNode::AttackEnd,    area, totalSeconds, tAttack,     1.0));
-    pts.push_back(vtx(EnvNode::HoldEnd,      area, totalSeconds, tHold,       1.0));
-    pts.push_back(vtx(EnvNode::DecayEnd,     area, totalSeconds, tDecay,      sus));  // sustain node
-    pts.push_back(vtx(EnvNode::ReleaseStart, area, totalSeconds, tSustainEnd, sus));  // plateau end
-    pts.push_back(vtx(EnvNode::ReleaseEnd,   area, totalSeconds, tRelease,    0.0));
+    pts.push_back(gateVtx(EnvNode::Origin,       area, 0.0,       0.0));
+    pts.push_back(gateVtx(EnvNode::AttackEnd,    area, pxAttack,  1.0));
+    pts.push_back(gateVtx(EnvNode::HoldEnd,      area, pxHold,    1.0));
+    pts.push_back(gateVtx(EnvNode::DecayEnd,     area, pxDecay,   sus));  // sustain node
+    pts.push_back(gateVtx(EnvNode::ReleaseStart, area, pxPlateau, sus));  // plateau end
+    pts.push_back(gateVtx(EnvNode::ReleaseEnd,   area, pxRelease, 0.0));
     return pts;
 }
 

src/vst/envelope_overlay.h

@@ -4,16 +4,37 @@
 // the DAW, while the editor shell (reasampler_editor.cpp) traces the polyline in an accent hue
 // and draws the node handles (via envelope_edit's hit-test).
 //
-// WHAT IT DRAWS. The amp envelope over the Sample view's hero waveform at accurate wall-clock
-// time (Simpler / Phase-Plant grammar):
+// WHAT IT DRAWS. The amp envelope over the Sample view's hero waveform (Simpler / Phase-Plant
+// grammar):
 //   * Gate    -> the AHDSR shape: attack ramp 0->1, hold plateau at 1, decay 1->sustain,
-//                sustain plateau, release sustain->0.
+//                sustain plateau, release sustain->0. Since there is no held note-off to draw
+//                against, Gate is a BOUNDED SCHEMATIC (FA2): a fixed fraction of the canvas
+//                width (kGateSustainDisplayFraction) is RESERVED for the sustain plateau, and
+//                the remaining "timed" width carries A/H/D AND the release at the sample's time
+//                scale — so A -> (H) -> D -> S-plateau -> R all render INSIDE the canvas and the
+//                release is a visible, draggable segment (it no longer trails past area.right).
 //   * Trigger -> the fade/%-length shape: fade-in 0->1, unity plateau, fade-out 1->0 anchored
-//                to playEnd (= lengthFraction of the post-start span).
-// The horizontal axis is wall-clock TIME across the waveform rect; the vertical axis is LEVEL
-// (0 at rect bottom, 1 at rect top). The overlay shares the waveform's time base so the drawn
-// shape lines up with the PCM under it: the same [0, frameCount] span waveform_view maps, so the
-// envelope's own duration is placed at the SAME frames the voice plays it over.
+//                to playEnd (= lengthFraction of the post-start span). Trigger keeps the
+//                waveform's exact time base so the shape lines up with the PCM under it.
+// The horizontal axis is TIME (Gate: schematic, see above; Trigger: wall-clock across the rect);
+// the vertical axis is LEVEL (0 at rect bottom, 1 at rect top).
+//
+// BOUNDS INVARIANT (FA2). EVERY vertex of EVERY polyline is clamped inside the canvas:
+// x in [area.left, area.right-1], y in [area.top, area.bottom-1] (half-open rect convention).
+// No node and no drawn segment ever exceeds the canvas — paint-time clipping of handles is no
+// longer needed (and never fires) in the shell.
+//
+// FA2 CONTRACT CHANGE — WAVE B SHELL AUTHOR, READ THIS:
+//   * The EnvNode enum is UNCHANGED (same node set, same draggable set — Origin + ReleaseStart
+//     remain the only non-draggable anchors).
+//   * ALL vertices are now in-bounds (see above). The shell's previous "skip handle when
+//     v.x >= waveArea.right" clip is dead code: ReleaseEnd (Gate) and FadeOutStart/LengthEnd
+//     (Trigger, at full length / zero fade-out) now land at area.right-1 and MUST get handles.
+//   * Gate's x-axis is schematic, not PCM-aligned (the sustain reserve compresses the timed
+//     region); Trigger's x-axis is still PCM-aligned.
+//   * nodeAtPoint (envelope_edit) now resolves to the NEAREST node within the grab radius,
+//     draw-order tie-break — coincident nodes (zero fade-out at the right edge, zero hold) are
+//     deterministically grabbable.
 //
 // DELIBERATELY ENGINE-FREE (house pattern — param_slider does the same). It does NOT depend on
 // sample_map / sampler_core (which would drag bank_book / wav_trim in). The shell reads the
@@ -44,7 +65,8 @@ enum class EnvMode { Gate, Trigger };
 //
 // Gate nodes:    Origin -> AttackEnd -> HoldEnd -> DecayEnd(=sustain corner) -> ReleaseStart
 //                -> ReleaseEnd. The sustain node is DecayEnd (its Y is the sustain level);
-//                ReleaseStart is a drawing-only plateau-end vertex.
+//                ReleaseStart is a drawing-only plateau-end vertex (the schematic note-off);
+//                release is edited by dragging ReleaseEnd.
 // Trigger nodes: Origin -> FadeInEnd -> FadeOutStart -> LengthEnd(playEnd, level 0). The fade-out
 //                ramp is the FadeOutStart->LengthEnd segment; LengthEnd is the playEnd terminal.
 enum class EnvNode {
@@ -55,7 +77,8 @@ enum class EnvNode {
                    //       Y sets sustainLevel)
     ReleaseStart,  // Gate: end of the sustain plateau / start of the release (sustain level) —
                    //       a DRAWING vertex only, not a draggable handle (release is edited at
-                   //       ReleaseEnd; this vertex tracks its X = sample end, Y = sustain level)
+                   //       ReleaseEnd; this vertex sits a fixed sustain-plateau width right of
+                   //       DecayEnd — the schematic note-off — Y = sustain level)
     ReleaseEnd,    // Gate: end of the release tail (level 0) — X sets releaseSeconds
     FadeInEnd,     // Trigger: top of the fade-in (level 1) — X sets fadeInFraction
     FadeOutStart,  // Trigger: end of the unity plateau / start of the fade-out (level 1) —
@@ -121,36 +144,46 @@ struct EnvVertex {
     }
 };
 
+// The fraction of the canvas width RESERVED for the Gate sustain-plateau display (FA2). The
+// plateau is a fixed-width schematic region between DecayEnd and ReleaseStart; the remaining
+// width is the "timed" region A/H/D/R map onto at the sample's time scale. One constant shared
+// by the forward map (here) and the inverse map (envelope_edit) so a drag tracks the cursor.
+inline constexpr double kGateSustainDisplayFraction = 0.15;
+
+// The pixel width of the Gate timed region: area.width() minus the sustain-plateau reserve,
+// floored at 1 px so the px<->seconds scale never degenerates for a non-empty area. Returns 0
+// for a zero/negative-width area. Shared by gatePolyline and envelope_edit's gate drag scale.
+int gateTimedWidth(const Rect& area);
+
 // Map an amp envelope to its polyline vertices inside `area`, over a sample of `totalSeconds`
 // wall-clock duration. `area` is the waveform rect (left/top inclusive, right/bottom exclusive);
-// x maps time 0..totalSeconds across [area.left, area.right], y maps level 0..1 across
-// [area.bottom-1 .. area.top] (level 1 at the TOP). The polyline reads left-to-right in draw
-// order, Origin first.
+// y maps level 0..1 across [area.bottom-1 .. area.top] (level 1 at the TOP). The polyline reads
+// left-to-right in draw order, Origin first.
 //
-// TIME BASE. The envelope's own segment durations are placed on the SAME time axis the waveform
-// occupies, so the curve lines up with the PCM:
-//   * Gate: attack/hold/decay run from t=0; the sustain plateau runs to the note-off. Since the
-//     overlay has no held note-off to draw against, the sustain plateau is drawn to the END of
-//     the sample (totalSeconds) and the release tail is drawn AFTER that boundary — i.e. the
-//     release is appended past the sample end (the standard "release after key-up at end of
-//     view" convention). When attack+hold+decay already exceed totalSeconds the plateau collapses
-//     to zero width (nodes clamp to the sample end) and release still trails past it.
-//   * Trigger: the played span is lengthFraction * totalSeconds; fade-in/out are fractions OF
-//     that played span. Nodes past the played span never appear (LengthEnd/FadeOutEnd sit at the
-//     played span's right edge).
+// TIME BASE (FA2).
+//   * Gate: a bounded schematic. The canvas splits into a TIMED region of gateTimedWidth(area)
+//     px — where attack/hold/decay run from t=0 and the release ramp runs after the plateau, all
+//     at totalSeconds-over-timed-width scale — plus a FIXED sustain plateau of
+//     (width - timedWidth) px between DecayEnd and ReleaseStart (the schematic note-off). Every
+//     vertex x clamps to area.right-1, so when the stages overrun the visible span the trailing
+//     nodes pile up (still monotonic, still in-bounds, still draggable back left).
+//   * Trigger: the waveform's exact time base (PCM-aligned). The played span is
+//     lengthFraction * totalSeconds; fade-in/out are fractions OF that played span. Nodes past
+//     the played span never appear (FadeOutStart/LengthEnd sit at the played span's right edge).
 //
-// A time beyond totalSeconds (the Gate release tail) maps past area.right — the shell clips at
-// paint time (the same way waveform_view lets a frame past the count pin the marker). A degenerate
-// area (zero width/height) or totalSeconds <= 0 yields the two-point flat baseline [Origin, end at
-// level 0] so the shell always has a drawable line. Pure — same inputs, same polyline.
+// BOUNDS: every vertex is inside the canvas — x in [area.left, area.right-1], y in
+// [area.top, area.bottom-1]. Nothing maps past area.right (the pre-FA2 release tail is gone). A
+// degenerate area (zero width/height) or totalSeconds <= 0 yields the two-point flat baseline
+// [Origin, end at level 0] so the shell always has a drawable line. Pure — same inputs, same
+// polyline.
 std::vector<EnvVertex> buildEnvelopePolyline(const AmpEnvelope& env, const Rect& area,
                                              double totalSeconds);
 
-// Map a time (seconds) to a pixel x inside `area`: t=0 -> area.left, t=totalSeconds -> area.right,
-// linear. t is NOT clamped on the high side (a Gate release past the sample end maps past
-// area.right, by design — see buildEnvelopePolyline); t < 0 pins to area.left. A zero-width area
-// or totalSeconds <= 0 yields area.left. Pure — the shared time->x map both the polyline and the
-// node hit-test (envelope_edit) use, so the drawn handle and its grab region agree.
+// Map a time (seconds) to a pixel x inside `area`: t=0 -> area.left, t=totalSeconds ->
+// area.right-1, linear, CLAMPED on both sides (t < 0 pins to area.left; t past totalSeconds pins
+// to area.right-1 — the in-bounds invariant, FA2). A zero-width area or totalSeconds <= 0 yields
+// area.left. Pure — the shared time->x map the Trigger polyline and the node hit-test
+// (envelope_edit) use, so the drawn handle and its grab region agree.
 int timeToX(const Rect& area, double totalSeconds, double t);
 
 // Map a level (0..1) to a pixel y inside `area`: level 1 -> area.top, level 0 -> area.bottom-1