fix: pin the waveform arbitration in a testable predicate, close round-4 review minors

Extracts resolveWaveformClaim (core/instrument/ui/spline_edit) so the shell's node/tab/marker click resolution is unit-tested directly, not just its input geometry; folds the staged-envelope node into it; fixes comment accuracy, a cost regression, and test fidelity issues.

src/core/instrument/engine/play_params.h

@@ -195,12 +195,10 @@ bool splineActive(const Play& p) {
            (p.filter.enabled && p.filterSpline.mode == EnvMode::Spline);
 }
 
-// The one enforcement of the rule above: forces `p` to Trigger the instant it goes
-// splineActive. Every path that can leave `p` in a state splineActive() would newly return true
-// for — resolving stored params toward the engine, or an editor control edit that can flip a
-// mode/enable toggle — routes through this, so none of them can reopen the Gate+spline hole
-// splineActive's own doc comment describes. Header-inline and allocation-free: play_params.h
-// sits on the per-voice-per-sample include path.
+// The one enforcement of splineActive's rule (see its doc above). Header-inline and
+// allocation-free: play_params.h sits on the per-voice-per-sample include path. Both callers —
+// resolvePlay (sample_map.cpp) and the editor's applyControl — route through here, so the two
+// cannot drift apart.
 template <class Play>
 void enforceGateUnavailableWhileDrawn(Play& p) {
     if (splineActive(p)) p.playMode = PlayMode::Trigger;

src/core/instrument/ui/CMakeLists.txt

@@ -24,10 +24,8 @@ reasampler_pure_library(waveform_view
     SOURCES waveform_view.cpp
     LINK PUBLIC editor_geometry peaks PRIVATE sample_bands)
 # sample_bands is linked directly here because the test exercises the lane metrics that
-# waveform_view does not re-export. velocity_curve is linked for the smallest-target-first
-# arbitration tests, which pin the geometric facts editor_input_waveform.cpp's node/tab/marker
-# resolution depends on (the shell itself has no test target).
-reasampler_test(waveform_view LINK waveform_view sample_bands velocity_curve)
+# waveform_view does not re-export.
+reasampler_test(waveform_view LINK waveform_view sample_bands)
 
 reasampler_pure_library(browser_scroll
     SOURCES browser_scroll.cpp
@@ -63,7 +61,12 @@ reasampler_test(deck_groups LINK deck_groups sample_bands)
 reasampler_pure_library(spline_edit
     SOURCES spline_edit.cpp
     LINK PUBLIC editor_geometry velocity_curve)
-reasampler_test(spline_edit LINK spline_edit)
+# waveform_view and sample_bands are linked for the test only: resolveWaveformClaim's
+# smallest-target-first tests build the real node/tab/marker geometry
+# editor_input_waveform.cpp's mouseDownWaveform composes (the shell that calls it has no test
+# target of its own), which needs waveform_view's marker/tab primitives and sample_bands'
+# kWaveformMinHeight floor.
+reasampler_test(spline_edit LINK spline_edit waveform_view sample_bands)
 
 reasampler_pure_library(curve_popup SOURCES curve_popup.cpp LINK PUBLIC editor_geometry)
 # velocity_curve is linked for the test only: the sheet's geometry is domain-agnostic, and

src/core/instrument/ui/spline_edit.cpp

@@ -26,4 +26,14 @@ VelocityCurve::Box splineOverlayBox(const OverlayArea& area) {
     return VelocityCurve::Box{area.rect.x, area.rect.y, area.rect.width, area.rect.height};
 }
 
+WaveformClaimant resolveWaveformClaim(const WaveformClaim& node, const WaveformClaim& tab,
+                                      const WaveformClaim& marker, SplineGesture gesture) {
+    if (gesture == SplineGesture::kControlLeft && node.hit) return WaveformClaimant::kNode;
+    if (node.hit && (!tab.hit || node.area <= tab.area) && (!marker.hit || node.area <= marker.area))
+        return WaveformClaimant::kNode;
+    if (tab.hit && (!marker.hit || tab.area <= marker.area)) return WaveformClaimant::kTab;
+    if (marker.hit) return WaveformClaimant::kMarker;
+    return WaveformClaimant::kNone;
+}
+
 }  // namespace reasampler::instrument::ui

src/core/instrument/ui/spline_edit.h

@@ -1,11 +1,13 @@
 // spline_edit.h — the point-editing grammar's CLICK resolution: add/grab/delete/toggle from a
-// single (x, y). Both spline consumers — the velocity-curve popup and the spline EG overlay —
-// route their mouse-down through it, so the two cannot drift into two click grammars. Two more
-// gesture rules complete the grammar but live in the shell (see the note near the bottom of this
-// file). Mirror of envelope_edit otherwise: decision logic only, no host types, no drawing.
+// single (x, y), plus resolveWaveformClaim, the waveform overlay's cross-affordance arbitration
+// (node vs. crossfade tab vs. marker). Both spline consumers — the velocity-curve popup and the
+// spline EG overlay — route their mouse-down through the click grammar, so the two cannot drift
+// apart. Decision logic only, no host types, no drawing; mirror of envelope_edit otherwise.
 
 #pragma once
 
+#include <cstdint>
+
 #include "core/instrument/engine/velocity_curve.h"
 #include "core/instrument/ui/editor_geometry.h"  // Rect / OverlayArea
 
@@ -51,4 +53,28 @@ VelocityCurve::Box splineOverlayBox(const OverlayArea& area);
 //   strictly in-box, since splineOverlayBox has no inset — editor_input_waveform.cpp's
 //   splineOverlayClick.
 
+// One arbitration candidate: whether the affordance was hit under the cursor, and its own
+// pick-target area (nominal, per its own module's constants — not the actual clipped pixel
+// count; see resolveWaveformClaim).
+struct WaveformClaim {
+    bool hit = false;
+    std::int64_t area = 0;
+};
+
+// Which affordance a waveform-overlay click claims.
+enum class WaveformClaimant { kNone, kNode, kTab, kMarker };
+
+// The overlay's cross-affordance arbitration: a contour node (or, mutually exclusively, a
+// staged envelope's drag node — both feed the same `node` slot), the loop crossfade tab, and a
+// marker's full-height column can all claim the same pixel. Hit gates a candidate out
+// entirely; among the ones that hit, the SMALLEST nominal area wins — the marker column is the
+// odd one out (its target is the whole overlay height), so it only wins where nothing narrower
+// also claims the click. Ties go to whichever is checked first: node, then tab, then marker —
+// no live geometry produces a tie except tab-vs-marker, which the tab correctly wins (see
+// editor_input_waveform.cpp's mouseDownWaveform for the live constants). A control-click has no
+// tab/marker meaning (they answer plain grabs only), so it resolves to the node whenever the
+// node is in the running, regardless of area.
+WaveformClaimant resolveWaveformClaim(const WaveformClaim& node, const WaveformClaim& tab,
+                                      const WaveformClaim& marker, SplineGesture gesture);
+
 }  // namespace reasampler::instrument::ui

src/shell/instrument/editor_input_waveform.cpp

@@ -39,88 +39,88 @@ bool ReaSamplerEditor::mouseDownWaveform(const FaceLayout& fl, int x, int y) {
                                       ? SplineGesture::kControlLeft
                                       : SplineGesture::kLeft;
 
-    // Envelope nodes first (they sit on top of the markers), then the wave markers. With no
-    // envelope overlay-active — or with its deck group's enable toggle off, which makes the
-    // same params' knobs inert — there are no grabbable nodes and the markers take every grab.
+    // The staged envelope's draggable node and the drawn contour's node are mutually exclusive
+    // (overlayEnvInert flips the staged one inert exactly when its envelope is in Spline mode),
+    // so at most one of the two hit-tests below is ever live for the same click — both feed the
+    // SAME arbitration slot below rather than either one getting its own check-order return.
     const double rate = liveSampleRate();
     const bool nodesLive =
         overlayEnv_ != OverlayEnv::kNone && !overlayEnvInert(overlayEnv_, gates);
+    NodeHit envNodeHit;
+    StageEnvelope env;
     if (rate > 0.0 && nodesLive) {
         const std::int64_t startFrame = params_.startPoint.value_or(0);
-        const StageEnvelope env = packEnvelope(overlayEnv_, params_.play, frames, startFrame);
+        env = packEnvelope(overlayEnv_, params_.play, frames, startFrame);
         const double totalSeconds = static_cast<double>(frames) / rate;
-        const NodeHit nh = nodeAtPoint(env, overlay, totalSeconds, x, y);
-        if (nh.hit) {
-            drag_ = DragKind::kEnvNode;
-            envNode_ = nh.node;
-            dragStartX_ = x;
-            dragStartY_ = y;
-            dragStartEnv_ = env;
-            dragSampleFrames_ = frames;
-            dragStartParams_ = params_;
-            return true;  // node moves once the cursor drags
-        }
+        envNodeHit = nodeAtPoint(env, overlay, totalSeconds, x, y);
     }
+
     const SetupMarkers m = pickedMarkers(frames);
     const std::int64_t markerFrames[3] = {m.start, m.loopStart, m.loopEnd};
 
-    // Three affordances can claim the same pixel: a contour node (a small fixed pick box), the
-    // crossfade tab (a small clipped top-strip tab), and a marker's full-height grab column
-    // (waveform_view.h's tab-vs-column split already keeps the tab apart from ITS OWN column;
-    // this is the cross-affordance case on top of that). Resolving by any fixed check order
-    // shadows whichever one loses the tie — this seam regressed twice from exactly that fix.
-    // Instead measure each claimant's own target area and let the SMALLEST hit win: the marker
-    // column is the odd one out (its target is the whole band height), so it only wins where
-    // nothing narrower also claims the pixel. Never add here (kAdd is only tried once nothing
-    // else has claimed the click, below).
-    struct Candidate {
-        bool hit = false;
-        std::int64_t area = 0;
-    };
-
-    Candidate node;
-    if (splineLive) {
+    // Three affordances can claim the same pixel: a node (the staged envelope's or the drawn
+    // contour's — a small fixed pick box either way), the crossfade tab (a small clipped
+    // top-strip tab), and a marker's full-height grab column (waveform_view.h's tab-vs-column
+    // split already keeps the tab apart from ITS OWN column; this is the cross-affordance case
+    // on top of that). resolveWaveformClaim (spline_edit.h) is the ONE arbitration: it measures
+    // each claimant's own NOMINAL target area and lets the smallest hit win, since a fixed check
+    // order shadows whichever one loses the tie — this seam regressed twice from exactly that
+    // fix. Never add here (kAdd is only tried once nothing else has claimed the click, below).
+    WaveformClaim node;
+    if (envNodeHit.hit) {
+        constexpr std::int64_t side = 2 * kNodeGrabRadius + 1;
+        node = {true, side * side};
+    } else if (splineLive) {
         const VelocityCurve::Box box = splineOverlayBox(overlay);
         // Also require strict in-box, matching splineOverlayClick's own narrowing (spline_edit.h's
         // grammar note) — otherwise this candidate could "win" the arbitration below for a click
         // splineOverlayClick would then refuse, silently swallowing it instead of falling through
         // to the tab/marker checks.
         if (contains(overlay.rect, x, y) && splineFor(overlayEnv_).pointAtPixel(box, x, y) >= 0) {
-            node.hit = true;
             constexpr std::int64_t side = 2 * kCurveNodeGrabRadius + 1;
-            node.area = side * side;
+            node = {true, side * side};
         }
     }
 
-    Candidate tab;
     const Rect tabRect =
         m.hasLoop ? markerHandleRect(overlay, frames, m.loopStart - m.crossfade) : Rect{};
-    if (m.hasLoop && contains(tabRect, x, y)) {
-        tab.hit = true;
-        tab.area = static_cast<std::int64_t>(tabRect.width) * tabRect.height;
-    }
+    const WaveformClaim tab = (m.hasLoop && contains(tabRect, x, y))
+                                  ? WaveformClaim{true, static_cast<std::int64_t>(tabRect.width) *
+                                                            tabRect.height}
+                                  : WaveformClaim{};
 
+    // Nominal, not actual: markerAtPoint clips the column at the overlay edges (a marker at
+    // frame 0 has 6 usable columns, not 11) and the node's fixed side clips too at a pick-box
+    // corner. Both overestimate in the direction that already produces the intended winner, so
+    // the arbitration runs on NOMINAL area, not the measured hit-testable pixel count.
     const int markerHit = markerAtPoint(overlay, frames, markerFrames, 3, x, y);
-    Candidate marker;
-    if (markerHit >= 0) {
-        marker.hit = true;
-        marker.area = static_cast<std::int64_t>(2 * kMarkerGrabWidth + 1) * overlay.rect.height;
-    }
+    const WaveformClaim marker =
+        (markerHit >= 0)
+            ? WaveformClaim{true, static_cast<std::int64_t>(2 * kMarkerGrabWidth + 1) *
+                                       overlay.rect.height}
+            : WaveformClaim{};
 
-    // Node checked before marker on an area tie so a degenerate (zero-height) overlay still
-    // prefers the node — unreachable in practice (sample_bands floors the band well above it),
-    // kept only so this arbitration has one well-defined answer for every input, not just the
-    // ones the current geometry constants happen to produce.
-    if (node.hit && (!tab.hit || node.area <= tab.area) && (!marker.hit || node.area <= marker.area)) {
-        return splineOverlayClick(overlay, x, y, gesture, /*addOnEmptySpace=*/false);
-    }
-    if (tab.hit && (!marker.hit || tab.area <= marker.area)) {
-        beginMarkerDrag(WaveMarker::kLoopXfade, m, frames, x);
-        return true;
-    }
-    if (marker.hit) {
-        beginMarkerDrag(static_cast<WaveMarker>(markerHit), m, frames, x);
-        return true;
+    switch (resolveWaveformClaim(node, tab, marker, gesture)) {
+        case WaveformClaimant::kNode:
+            if (envNodeHit.hit) {
+                drag_ = DragKind::kEnvNode;
+                envNode_ = envNodeHit.node;
+                dragStartX_ = x;
+                dragStartY_ = y;
+                dragStartEnv_ = env;
+                dragSampleFrames_ = frames;
+                dragStartParams_ = params_;
+                return true;  // node moves once the cursor drags
+            }
+            return splineOverlayClick(overlay, x, y, gesture, /*addOnEmptySpace=*/false);
+        case WaveformClaimant::kTab:
+            beginMarkerDrag(WaveMarker::kLoopXfade, m, frames, x);
+            return true;
+        case WaveformClaimant::kMarker:
+            beginMarkerDrag(static_cast<WaveMarker>(markerHit), m, frames, x);
+            return true;
+        case WaveformClaimant::kNone:
+            break;
     }
     // Nothing else wanted the click: now the drawn contour may take the empty space.
     if (splineLive) return splineOverlayClick(overlay, x, y, gesture, /*addOnEmptySpace=*/true);

src/shell/instrument/editor_session.cpp

@@ -186,8 +186,12 @@ ReaSamplerEditor::SetupMarkers ReaSamplerEditor::pickedMarkers(std::int64_t fram
     // Seed from the bank's intrinsic loop (fact about the file), then let the parameter set's
     // override win (the instrument's performance choice). Read the loop intrinsic from the
     // live bank blob (the same path selectSample uses); when that is not readable (extension
-    // absent / not yet parsed) the instance-owned ref carries the same intrinsics.
-    if (processor_) {
+    // absent / not yet parsed) the instance-owned ref carries the same intrinsics. Skipped
+    // entirely once an override is already set — it would just be overwritten below, and the
+    // bridge read + JSON parse it costs is real (mouseDownWaveform's arbitration calls this on
+    // every waveform click, not just marker grabs, to know whether a tab or marker candidate
+    // hits at all).
+    if (processor_ && !params_.loopOverride) {
         std::optional<SelectedSample> sel;
         auto banksJson =
             processor_->bridge().readReasamplerExtState(reasampler::kProjExtBanksKey);