reasampler/tests/test_deck_groups.cpp

// 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 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 pinned Gate widths and row assignment,
// that no face leaves slack where its dropped controls were and that a Gate/Spline/Gate round
// trip restores the layout exactly, 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,
// and which selections are inert).

#include "../src/core/instrument/ui/deck_groups.h"
#include "../src/core/instrument/ui/sample_bands.h"

#include <cmath>
#include <cstdio>
#include <vector>

using namespace reasampler;
using namespace reasampler::instrument::ui;

static int g_fail = 0;
#define CHECK(cond) do { if(!(cond)) { \
    std::printf("FAIL line %d: %s\n", __LINE__, #cond); ++g_fail; } } while(0)

// The editor's floor width, which is also its default (checkSizeConstraint clamps to it), less
// the band allocator's kPad inset on each side.
static constexpr int kAvailAtMinWidth = kEditorMinWidth - 2 * kPad;

static int indexOfGroup(const std::vector<DeckGroupDesc>& g, int id) {
    for (std::size_t i = 0; i < g.size(); ++i) {
        if (g[i].id == id) return static_cast<int>(i);
    }
    return -1;
}

static int cell(DeckParam p) { return static_cast<int>(p); }

static void testDeckReadsPitchThenFilterThenAmpLeftToRight() {
    for (PlayMode mode : {PlayMode::Gate, PlayMode::Trigger}) {
        const std::vector<DeckGroupDesc> g = sampleDeckGroups(mode);
        const int pitch  = indexOfGroup(g, kGroupPitch);
        const int penv   = indexOfGroup(g, kGroupPitchEnv);
        const int filt   = indexOfGroup(g, kGroupFilter);
        const int fenv   = indexOfGroup(g, kGroupFilterEnv);
        const int amp    = indexOfGroup(g, kGroupAmpEnv);
        CHECK(pitch >= 0 && penv >= 0 && filt >= 0 && fenv >= 0 && amp >= 0);
        // The signal flow, left to right. Each envelope group trails its own stage.
        CHECK(pitch < penv);
        CHECK(penv < filt);
        CHECK(filt < fenv);
        CHECK(fenv < amp);
        // VELOCITY then the two instance-wide groups at the end. Velocity sits IMMEDIATELY
        // 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));
    }
}

// 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 width reserve, not a control
    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 = {
        cell(DeckParam::kFilterMorph),  cell(DeckParam::kFilterCutoff),
        cell(DeckParam::kFilterQ),      cell(DeckParam::kFilterDrive),
        cell(DeckParam::kFilterModAmt), cell(DeckParam::kFilterVel),
        cell(DeckParam::kFilterKeyTrack)};
    CHECK(f.cellIds == expected);
    // Off by default is a state question, but reachability is a layout one: the enable
    // toggle is in the caption row and the morph law in the knob row.
    CHECK(f.captionToggle.id == cell(DeckParam::kFilterEnable));
    CHECK(f.rowToggle.id == cell(DeckParam::kFilterLaw));

    const DeckGroupDesc& fe = g[static_cast<std::size_t>(indexOfGroup(g, kGroupFilterEnv))];
    const std::vector<int> env = {
        cell(DeckParam::kFilterEnvAttack), cell(DeckParam::kFilterEnvHold),
        cell(DeckParam::kFilterEnvDecay),  cell(DeckParam::kFilterEnvSustain),
        cell(DeckParam::kFilterEnvRelease)};
    CHECK(fe.cellIds == env);
    // The filter envelope has no enable of its own — the FILTER group's toggle governs both.
    CHECK(fe.captionToggle.id == -1);
    CHECK(fe.rowToggle.id == -1);
}

// Exactly the three envelope decks carry an overlay-select radio, each its own, and no other
// group has one — the exclusivity the shell enforces is only meaningful if the id space is.
static void testOnlyTheThreeEnvelopeDecksCarryARadio() {
    for (PlayMode mode : {PlayMode::Gate, PlayMode::Trigger}) {
        const std::vector<DeckGroupDesc> g = sampleDeckGroups(mode);
        int radios = 0;
        for (const DeckGroupDesc& d : g) {
            if (d.captionRadio.id < 0) continue;
            ++radios;
            const int want = d.id == kGroupAmpEnv      ? cell(DeckParam::kAmpEnvSelect)
                           : d.id == kGroupPitchEnv    ? cell(DeckParam::kPitchEnvSelect)
                           : d.id == kGroupFilterEnv   ? cell(DeckParam::kFilterEnvSelect)
                                                       : -1;
            CHECK(d.captionRadio.id == want);
        }
        CHECK(radios == 3);
    }
}

// The mode-driven shape switch, on BOTH the amp and the filter envelope: Gate shows the
// AHDSR's five stages, Trigger the AHD's three (behind the play span on the amp deck), and
// neither mode leaks the other's controls onto the deck.
static void testGateAndTriggerFacesCarryTheirOwnShapes() {
    const std::vector<DeckGroupDesc> gate = sampleDeckGroups(PlayMode::Gate);
    const std::vector<DeckGroupDesc> trig = sampleDeckGroups(PlayMode::Trigger);
    const DeckGroupDesc& gAmp = gate[static_cast<std::size_t>(indexOfGroup(gate, kGroupAmpEnv))];
    const DeckGroupDesc& tAmp = trig[static_cast<std::size_t>(indexOfGroup(trig, kGroupAmpEnv))];
    const std::vector<int> gateAmp = {cell(DeckParam::kAttack), cell(DeckParam::kHold),
                                      cell(DeckParam::kDecay), cell(DeckParam::kSustain),
                                      cell(DeckParam::kRelease)};
    const std::vector<int> trigAmp = {cell(DeckParam::kTrigLength), cell(DeckParam::kTrigAttack),
                                      cell(DeckParam::kTrigHold), cell(DeckParam::kTrigDecay),
                                      -1};
    CHECK(gAmp.cellIds == gateAmp);
    CHECK(tAmp.cellIds == trigAmp);

    const DeckGroupDesc& gFe = gate[static_cast<std::size_t>(indexOfGroup(gate, kGroupFilterEnv))];
    const DeckGroupDesc& tFe = trig[static_cast<std::size_t>(indexOfGroup(trig, kGroupFilterEnv))];
    const std::vector<int> trigFe = {cell(DeckParam::kFilterTrigAttack),
                                     cell(DeckParam::kFilterTrigHold),
                                     cell(DeckParam::kFilterTrigDecay), -1, -1};
    CHECK(tFe.cellIds == trigFe);
    CHECK(gFe.cellIds != tFe.cellIds);
    // Same cell count either way, so the group's width — and its neighbours' placement —
    // survives a mode flip.
    CHECK(gFe.cellIds.size() == tFe.cellIds.size());
    CHECK(deckGroupWidth(gFe) == deckGroupWidth(tFe));
}

// Every SLOPED stage knob carries an inner curve dial; Hold, Sustain, and everything that is
// not a stage carries none. This is the "which segments are sloped" rule, asserted rather than
// read.
static void testOnlySlopedStageKnobsCarryAnInnerCurveDial() {
    const DeckParam sloped[] = {
        DeckParam::kAttack, DeckParam::kDecay, DeckParam::kRelease,
        DeckParam::kTrigAttack, DeckParam::kTrigDecay,
        DeckParam::kPitchEnvAttack, DeckParam::kPitchEnvDecay,
        DeckParam::kFilterEnvAttack, DeckParam::kFilterEnvDecay, DeckParam::kFilterEnvRelease,
        DeckParam::kFilterTrigAttack, DeckParam::kFilterTrigDecay,
    };
    for (DeckParam p : sloped) {
        const DeckParam c = curveParamFor(p);
        CHECK(c != DeckParam::kCount);
        // A curve control is itself flat — no inner dial on an inner dial.
        CHECK(curveParamFor(c) == DeckParam::kCount);
    }
    const DeckParam flat[] = {
        DeckParam::kHold, DeckParam::kSustain, DeckParam::kTrigHold,
        DeckParam::kPitchEnvHold, DeckParam::kFilterEnvHold, DeckParam::kFilterEnvSustain,
        DeckParam::kFilterTrigHold, DeckParam::kTrigLength, DeckParam::kPitchEnvDepth,
        DeckParam::kFilterCutoff, DeckParam::kMasterGain, DeckParam::kKeyTrack,
    };
    for (DeckParam p : flat) CHECK(curveParamFor(p) == DeckParam::kCount);

    // Every sloped knob maps to a DISTINCT curve control — a copy-paste that pointed two
    // stages at one exponent would tie two dials together silently.
    for (std::size_t i = 0; i < sizeof(sloped) / sizeof(sloped[0]); ++i) {
        for (std::size_t j = i + 1; j < sizeof(sloped) / sizeof(sloped[0]); ++j) {
            CHECK(curveParamFor(sloped[i]) != curveParamFor(sloped[j]));
        }
    }
}

static void testAmpGroupWidthSurvivesAGateTriggerFlip() {
    // The reserved blanks are what stop a mode flip reflowing the groups beside AMP.
    const std::vector<DeckGroupDesc> gate = sampleDeckGroups(PlayMode::Gate);
    const std::vector<DeckGroupDesc> trig = sampleDeckGroups(PlayMode::Trigger);
    const DeckGroupDesc& a = gate[static_cast<std::size_t>(indexOfGroup(gate, kGroupAmpEnv))];
    const DeckGroupDesc& b = trig[static_cast<std::size_t>(indexOfGroup(trig, kGroupAmpEnv))];
    CHECK(deckGroupWidth(a) == deckGroupWidth(b));
    CHECK(a.cellIds.size() == b.cellIds.size());
    CHECK(b.cellIds[4] == -1);  // the Trigger face's one reserved blank
    // Every other group is mode-independent, so the whole deck's height is too.
    CHECK(deckHeight(gate, kAvailAtMinWidth) == deckHeight(trig, kAvailAtMinWidth));
}

static void testWrappedDeckHeightAtTheEditorFloorWidth() {
    const std::vector<DeckGroupDesc> g = sampleDeckGroups(PlayMode::Gate);
    // At the floor (== default) 840 the deck takes three rows: PITCH + PITCH ENV + FILTER fill
    // the first (818 of the 824 available — six px of headroom, so one more FILTER cell would
    // wrap the group and reflow everything under it), FILTER ENV + AMP + VELOCITY the second,
    // 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.
    const DeckLayout dl = layoutDeck(g, kPad, 0, kAvailAtMinWidth);
    CHECK(dl.groups.size() == g.size());
    for (const DeckGroupLayout& gl : dl.groups) {
        CHECK(gl.box.x >= kPad);
        CHECK(gl.box.height == kDeckGroupH);
    }
}

// The guard the raised floor exists to provide: at the smallest window the host can produce,
// the deck band still lands inside the client area AND the waveform still gets its two-lane
// floor. Growing the deck past what 620 px can hold fails HERE instead of silently pushing
// FILTER ENV / AMP / VOICE / MASTER off-screen, where there is no scroll to reach them.
static void testDeckFitsInsideTheEnforcedMinimumWindow() {
    for (PlayMode mode : {PlayMode::Gate, PlayMode::Trigger}) {
        const std::vector<DeckGroupDesc> g = sampleDeckGroups(mode);
        const int h = deckHeight(g, kAvailAtMinWidth);
        const SampleBands b = computeSampleBands(kEditorMinWidth, kEditorMinHeight, h);
        CHECK(deckRowCount(g, kAvailAtMinWidth) == 3);  // either face, three rows at the floor
        CHECK(b.decks.height == h);
        // Bottom-anchored INSIDE the pad is the whole assertion: the degrade path pushes the
        // deck down until the waveform hits its floor, so any deck too tall to fit stops
        // landing on this exact line. A `<= kEditorMinHeight` bound would not catch it — the
        // degrade can still leave the deck ending at the window edge.
        CHECK(b.decks.bottom() == kEditorMinHeight - kPad);
        CHECK(b.waveform.height >= kWaveformMinHeight);
    }
}

static void testHitTestResolvesTheNewFilterControls() {
    const std::vector<DeckGroupDesc> g = sampleDeckGroups(PlayMode::Gate);
    const DeckLayout dl = layoutDeck(g, kPad, 40, kAvailAtMinWidth);
    const DeckGroupLayout& f =
        dl.groups[static_cast<std::size_t>(indexOfGroup(g, kGroupFilter))];

    // Every knob cell resolves to its own id, from the centre of its cell.
    for (const DeckCellLayout& c : f.cells) {
        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(f.cells.size() == 7);
    CHECK(f.cells[1].id == cell(DeckParam::kFilterCutoff));

    // The enable toggle's two segments and the morph-law row toggle's two.
    const DeckHit off = hitTestDeck(dl, f.captionToggle.seg0.x + 2,
                                    f.captionToggle.seg0.y + 2);
    CHECK(off.kind == DeckHitKind::CaptionToggle);
    CHECK(off.id == cell(DeckParam::kFilterEnable) && off.segment == 0);
    const DeckHit on = hitTestDeck(dl, f.captionToggle.seg1.x + 2,
                                   f.captionToggle.seg1.y + 2);
    CHECK(on.id == cell(DeckParam::kFilterEnable) && on.segment == 1);

    const DeckHit band = hitTestDeck(dl, f.rowToggle.seg0.x + 2, f.rowToggle.seg0.y + 2);
    CHECK(band.kind == DeckHitKind::RowToggle);
    CHECK(band.id == cell(DeckParam::kFilterLaw) && band.segment == 0);
    const DeckHit notch = hitTestDeck(dl, f.rowToggle.seg1.x + 2, f.rowToggle.seg1.y + 2);
    CHECK(notch.id == cell(DeckParam::kFilterLaw) && notch.segment == 1);

    // The filter-envelope knobs resolve too, and are distinct ids from the amp's.
    const DeckGroupLayout& fe =
        dl.groups[static_cast<std::size_t>(indexOfGroup(g, kGroupFilterEnv))];
    const DeckHit attack = hitTestDeck(dl, fe.cells[0].cell.x + 4, fe.cells[0].cell.y + 4);
    CHECK(attack.kind == DeckHitKind::Knob);
    CHECK(attack.id == cell(DeckParam::kFilterEnvAttack));
    CHECK(attack.id != cell(DeckParam::kAttack));
}

static void testBipolarKnobLawRoundTripsAndIsExactAtCentre() {
    // Centre is EXACT in both directions: a knob parked at 0.5 stores 0, and 0 reads back
    // 0.5 — no residual modulation from a rounding hair.
    CHECK(deckBipolarFromNorm(0.5) == 0.0);
    CHECK(deckNormFromBipolar(0.0) == 0.5);
    CHECK(deckBipolarFromNorm(0.0) == -1.0);
    CHECK(deckBipolarFromNorm(1.0) == 1.0);
    for (int i = 0; i <= 200; ++i) {
        const double norm = static_cast<double>(i) / 200.0;
        CHECK(std::fabs(deckNormFromBipolar(deckBipolarFromNorm(norm)) - norm) < 1e-12);
        const double value = -1.0 + static_cast<double>(i) / 100.0;
        CHECK(std::fabs(deckBipolarFromNorm(deckNormFromBipolar(value)) - value) < 1e-12);
    }
    // Out of range clamps rather than extrapolating.
    CHECK(deckBipolarFromNorm(-3.0) == -1.0);
    CHECK(deckBipolarFromNorm(3.0) == 1.0);
    CHECK(deckNormFromBipolar(-3.0) == 0.0);
    CHECK(deckNormFromBipolar(3.0) == 1.0);
}

static void testEveryDeckControlIsClassifiedLiveOrReloading() {
    // 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::kFilterVel,
        DeckParam::kFilterKeyTrack,
        DeckParam::kAttack, DeckParam::kHold, DeckParam::kDecay, DeckParam::kSustain,
        DeckParam::kRelease,
        DeckParam::kTrigAttack, DeckParam::kTrigHold, DeckParam::kTrigDecay,
        DeckParam::kFilterEnvAttack, DeckParam::kFilterEnvHold, DeckParam::kFilterEnvDecay,
        DeckParam::kFilterEnvSustain, DeckParam::kFilterEnvRelease,
        DeckParam::kFilterTrigAttack, DeckParam::kFilterTrigHold, DeckParam::kFilterTrigDecay,
        DeckParam::kPitchEnvAttack, DeckParam::kPitchEnvHold, DeckParam::kPitchEnvDecay,
        DeckParam::kPitchEnvDepth,
        DeckParam::kAttackCurve, DeckParam::kDecayCurve, DeckParam::kReleaseCurve,
        DeckParam::kTrigAttackCurve, DeckParam::kTrigDecayCurve,
        DeckParam::kPitchEnvAttackCurve, DeckParam::kPitchEnvDecayCurve,
        DeckParam::kFilterEnvAttackCurve, DeckParam::kFilterEnvDecayCurve,
        DeckParam::kFilterEnvReleaseCurve,
        DeckParam::kFilterTrigAttackCurve, DeckParam::kFilterTrigDecayCurve,
    };
    for (DeckParam p : live) CHECK(isLiveDeckParam(p));

    // Everything else reloads or rebuilds; deck_groups.h is the home for why each exclusion
    // is excluded.
    const DeckParam reloads[] = {
        DeckParam::kPlayMode, DeckParam::kPitchEngine, DeckParam::kPitchEnvEnable,
        DeckParam::kFilterEnable, DeckParam::kFilterLaw,
        DeckParam::kAmpVelCurve, DeckParam::kPitchVelCurve, DeckParam::kFilterVelCurve,
        DeckParam::kKeyTrack, DeckParam::kTrigLength,
        DeckParam::kAmpEnvSelect, DeckParam::kPitchEnvSelect, DeckParam::kFilterEnvSelect,
        DeckParam::kAmpEnvMode, DeckParam::kPitchEnvMode, DeckParam::kFilterEnvMode,
        DeckParam::kVoiceCount, DeckParam::kVoiceMode,
        DeckParam::kMonoTrigger, DeckParam::kMasterGain,
    };
    for (DeckParam p : reloads) CHECK(!isLiveDeckParam(p));

    // COVERAGE, not cardinality: every id appears in EXACTLY ONE of the two lists. A sum check
    // would stay green if an edit duplicated one id and dropped another, leaving that one
    // unclassified.
    for (int i = 0; i < static_cast<int>(DeckParam::kCount); ++i) {
        const DeckParam p = static_cast<DeckParam>(i);
        int seen = 0;
        for (DeckParam q : live) if (q == p) ++seen;
        for (DeckParam q : reloads) if (q == p) ++seen;
        if (seen != 1) std::printf("  (deck id %d classified %d times)\n", i, seen);
        CHECK(seen == 1);
    }
}

static void testOnlyALiveControlsDragTakesTheLiveTier() {
    // isLiveDeckParam alone is not what a user experiences — liveCommitFor is, at the editor's
    // commit site. Inverting it has to FAIL a test rather than merely read wrong.
    CHECK(liveCommitFor(LiveDragKind::kDeckKnob, static_cast<int>(DeckParam::kFilterCutoff)));
    CHECK(liveCommitFor(LiveDragKind::kDeckKnob, static_cast<int>(DeckParam::kAttack)));
    // The Trigger amp is live now that the fade pair folded into the AHD — the one behavioural
    // consequence of that consolidation.
    CHECK(liveCommitFor(LiveDragKind::kDeckKnob, static_cast<int>(DeckParam::kTrigAttack)));
    CHECK(liveCommitFor(LiveDragKind::kDeckKnob, static_cast<int>(DeckParam::kTrigDecayCurve)));
    CHECK(!liveCommitFor(LiveDragKind::kDeckKnob, static_cast<int>(DeckParam::kTrigLength)));
    CHECK(!liveCommitFor(LiveDragKind::kDeckKnob, static_cast<int>(DeckParam::kMasterGain)));
    CHECK(!liveCommitFor(LiveDragKind::kDeckKnob, static_cast<int>(DeckParam::kAmpEnvSelect)));
    // The shell's processor-side sentinels (preview velocity is -2) and any out-of-range id
    // are not parameter-set controls, so they must never reach the enum.
    CHECK(!liveCommitFor(LiveDragKind::kDeckKnob, -2));
    CHECK(!liveCommitFor(LiveDragKind::kDeckKnob, -1));
    CHECK(!liveCommitFor(LiveDragKind::kDeckKnob, static_cast<int>(DeckParam::kCount)));
    // Every stage value an envelope node can reach is live, in either mode shape.
    CHECK(liveCommitFor(LiveDragKind::kEnvNode, -1));
    // Every other drag (markers, scrollbar, curve nodes) commits through a reload.
    CHECK(!liveCommitFor(LiveDragKind::kOther, static_cast<int>(DeckParam::kFilterCutoff)));
}

// --- The overlay selection state machine ---------------------------------------

static int radio(DeckParam p) { return static_cast<int>(p); }

// EXCLUSIVITY: picking another deck's radio switches to it outright — two envelopes can never
// be overlay-active at once, whatever the previous selection was.
static void testOverlaySelectionIsExclusiveAcrossTheThreeEnvelopeDecks() {
    const OverlayEnv states[] = {OverlayEnv::kNone, OverlayEnv::kAmp, OverlayEnv::kPitch,
                                 OverlayEnv::kFilter};
    for (OverlayEnv from : states) {
        if (from != OverlayEnv::kAmp) {
            CHECK(nextOverlaySelection(from, radio(DeckParam::kAmpEnvSelect)) == OverlayEnv::kAmp);
        }
        if (from != OverlayEnv::kPitch) {
            CHECK(nextOverlaySelection(from, radio(DeckParam::kPitchEnvSelect)) ==
                  OverlayEnv::kPitch);
        }
        if (from != OverlayEnv::kFilter) {
            CHECK(nextOverlaySelection(from, radio(DeckParam::kFilterEnvSelect)) ==
                  OverlayEnv::kFilter);
        }
    }
}

// kNone is a RESTING STATE the user can get back to: clicking the active radio clears it.
static void testClickingTheActiveOverlayRadioClearsToNone() {
    CHECK(nextOverlaySelection(OverlayEnv::kAmp, radio(DeckParam::kAmpEnvSelect)) ==
          OverlayEnv::kNone);
    CHECK(nextOverlaySelection(OverlayEnv::kPitch, radio(DeckParam::kPitchEnvSelect)) ==
          OverlayEnv::kNone);
    CHECK(nextOverlaySelection(OverlayEnv::kFilter, radio(DeckParam::kFilterEnvSelect)) ==
          OverlayEnv::kNone);
}

// A control that is not one of the three radios selects nothing and clears nothing.
static void testANonRadioIdLeavesTheOverlaySelectionAlone() {
    CHECK(overlayEnvForRadio(radio(DeckParam::kFilterCutoff)) == OverlayEnv::kNone);
    CHECK(overlayEnvForRadio(-1) == OverlayEnv::kNone);
    CHECK(nextOverlaySelection(OverlayEnv::kFilter, radio(DeckParam::kFilterCutoff)) ==
          OverlayEnv::kFilter);
    CHECK(nextOverlaySelection(OverlayEnv::kAmp, 9999) == OverlayEnv::kAmp);
}

// The two group gates, spelled the way the predicates read them. Spline flags default off, so
// a case that says nothing about them is asserting the staged behaviour.
static DeckEnableState gates(bool pitchEnv, bool filter) {
    DeckEnableState s;
    s.pitchEnvEnabled = pitchEnv;
    s.filterEnabled = filter;
    return s;
}

// An overlay whose deck group is switched OFF is inert, matching the drawn-but-dead knobs on
// the same params: a node drag must not reach a value the knob refuses.
static void testOverlayIsInertExactlyWhenItsGroupToggleIsOff() {
    CHECK(overlayEnvInert(OverlayEnv::kPitch, gates(/*pitchEnv=*/false, /*filter=*/true)));
    CHECK(!overlayEnvInert(OverlayEnv::kPitch, gates(true, true)));
    CHECK(overlayEnvInert(OverlayEnv::kFilter, gates(true, /*filter=*/false)));
    CHECK(!overlayEnvInert(OverlayEnv::kFilter, gates(true, true)));
    // Amp has no enable toggle, so it is never inert; kNone draws nothing to grab.
    CHECK(!overlayEnvInert(OverlayEnv::kAmp, gates(false, false)));
    CHECK(!overlayEnvInert(OverlayEnv::kNone, gates(false, false)));

    // The enable gate alone, which the SPLINE overlay reads: it survives a mode switch, so a
    // disabled group's contour is as dead as its knobs.
    CHECK(!overlayEnvEnabled(OverlayEnv::kPitch, gates(false, true)));
    CHECK(overlayEnvEnabled(OverlayEnv::kAmp, gates(false, false)));
    // ...while the staged overlay additionally goes inert once the envelope is drawn: its
    // nodes are no longer what the overlay is editing.
    DeckEnableState drawn = gates(true, true);
    drawn.ampSpline = true;
    CHECK(overlayEnvInert(OverlayEnv::kAmp, drawn));
    CHECK(overlayEnvEnabled(OverlayEnv::kAmp, drawn));
}

// 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, gates(/*pitchEnv=*/true, /*filter=*/false)));
    CHECK(!deckKnobInert(DeckParam::kFilterVelCurve, gates(true, true)));
    CHECK(deckKnobInert(DeckParam::kFilterCutoff, gates(true, false)));
    CHECK(!deckKnobInert(DeckParam::kFilterCutoff, gates(true, true)));
    CHECK(deckKnobInert(DeckParam::kPitchEnvDepth, gates(/*pitchEnv=*/false, true)));
    CHECK(!deckKnobInert(DeckParam::kPitchEnvDepth, gates(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 until an envelope is drawn.
    CHECK(!deckKnobInert(DeckParam::kAmpVelCurve, gates(false, false)));
    CHECK(!deckKnobInert(DeckParam::kAttack, gates(false, false)));
}

// A drawn envelope's STAGED segment knobs go inert; the mode toggle itself and the depth knobs
// that scale either shape stay live. (Which segment knobs, per envelope, is pinned in
// spline_egs_tests alongside the rest of the spline rules.)
static void testAModeToggleIsNeitherLiveNorAnOverlayRadio() {
    CHECK(!isLiveDeckParam(DeckParam::kAmpEnvMode));
    CHECK(!isLiveDeckParam(DeckParam::kPitchEnvMode));
    CHECK(!isLiveDeckParam(DeckParam::kFilterEnvMode));
    CHECK(overlayEnvForModeToggle(radio(DeckParam::kAmpEnvMode)) == OverlayEnv::kAmp);
    CHECK(overlayEnvForModeToggle(radio(DeckParam::kPitchEnvMode)) == OverlayEnv::kPitch);
    CHECK(overlayEnvForModeToggle(radio(DeckParam::kFilterEnvMode)) == OverlayEnv::kFilter);
    // A mode toggle must not be mistaken for the overlay-select radio beside it.
    CHECK(overlayEnvForRadio(radio(DeckParam::kAmpEnvMode)) == OverlayEnv::kNone);
    CHECK(overlayEnvForModeToggle(radio(DeckParam::kAmpEnvSelect)) == OverlayEnv::kNone);
}

// The three mode toggles ride each env group's caption slack, so the deck's wrapped geometry
// is unchanged by them: raising their segment width past the caption headroom would reflow the
// first row and push the deck to a fourth one (see testDeckFitsInsideTheEnforcedMinimumWindow).
static void testTheModeTogglesCostNoGroupWidth() {
    for (PlayMode mode : {PlayMode::Gate, PlayMode::Trigger}) {
        for (const DeckGroupDesc& g : sampleDeckGroups(mode)) {
            if (g.captionToggle2.id < 0) continue;
            DeckGroupDesc without = g;
            without.captionToggle2 = DeckToggleDesc{};
            CHECK(deckGroupWidth(g) == deckGroupWidth(without));
        }
    }
}

// A typical larger window, to check the same properties once the deck has re-wrapped.
static constexpr int kAvailAtLargerWidth = 1100 - 2 * kPad;

// The gap fix as a property of the shipped descriptors, not a picture: whichever face a
// mode-dependent group shows, its knob row still spans the group's whole reserved run. The
// Trigger faces drop Sustain and Release and get wider cells for it — never a hole where the
// dropped control was. What the run does not cover is the indivisible residue alone, strictly
// under one pixel per cell.
static void testNoFaceLeavesSlackWhereItsDroppedControlsWere() {
    for (int avail : {kAvailAtMinWidth, kAvailAtLargerWidth}) {
        for (PlayMode mode : {PlayMode::Gate, PlayMode::Trigger}) {
            const std::vector<DeckGroupDesc> g = sampleDeckGroups(mode);
            const DeckLayout dl = layoutDeck(g, kPad, 0, avail);
            CHECK(dl.groups.size() == g.size());
            for (std::size_t i = 0; i < dl.groups.size(); ++i) {
                const DeckGroupLayout& lay = dl.groups[i];
                const int reserved = static_cast<int>(g[i].cellIds.size()) * kDeckCellW;
                const std::size_t present = lay.cells.size();
                CHECK(present > 0);
                for (std::size_t k = 0; k < present; ++k) {
                    const DeckCellLayout& c = lay.cells[k];
                    CHECK(c.id >= 0);  // a reserve yields width, never a dead rect
                    CHECK(c.cell.width == lay.cells[0].cell.width);
                    if (k > 0) CHECK(c.cell.x == lay.cells[k - 1].cell.right());
                }
                const int covered = lay.cells.back().cell.right() - lay.cells.front().cell.x;
                CHECK(reserved - covered < static_cast<int>(present));
                CHECK(lay.cells.front().cell.x >= lay.box.x + kDeckGroupPadX);
                CHECK(lay.cells.back().cell.right() <= lay.box.right() - kDeckGroupPadX);
            }
        }
    }
}

// The "residue lands in symmetric end margins" rule is knob_deck's own (layoutGroup), pinned
// once by its synthetic residue>=2 fixture in test_knob_deck.cpp rather than restated here.

// Gate is the common face and it already packs correctly: pin its group widths and row
// assignment at the floor so a later edit anywhere in the deck cannot reflow it silently.
// (Measured from the shipped descriptors, not copied out of a failing run.)
static void testGateModeWidthsAndRowAssignmentAreUnchanged() {
    const std::vector<DeckGroupDesc> g = sampleDeckGroups(PlayMode::Gate);
    const struct { int id; int width; int row; } want[] = {
        {kGroupPitch, 150, 0}, {kGroupPitchEnv, 204, 0}, {kGroupFilter, 440, 0},
        {kGroupFilterEnv, 252, 1}, {kGroupAmpEnv, 252, 1}, {kGroupVelocity, 156, 1},
        {kGroupVoice, 152, 2}, {kGroupMaster, 60, 2},
    };
    CHECK(g.size() == sizeof(want) / sizeof(want[0]));
    const DeckLayout dl = layoutDeck(g, kPad, 0, kAvailAtMinWidth);
    for (std::size_t i = 0; i < dl.groups.size(); ++i) {
        CHECK(dl.groups[i].id == want[i].id);
        CHECK(deckGroupWidth(g[i]) == want[i].width);
        CHECK(dl.groups[i].box.width == want[i].width);
        CHECK(dl.groups[i].box.y == want[i].row * (kDeckGroupH + kDeckRowGap));
        // Gate carries no reserves, so its cells are the deck's base size.
        for (const DeckCellLayout& c : dl.groups[i].cells) CHECK(c.cell.width == kDeckCellW);
    }
}

static bool sameToggle(const DeckToggleLayout& a, const DeckToggleLayout& b) {
    return a.id == b.id && a.seg0 == b.seg0 && a.seg1 == b.seg1;
}

static bool sameLayout(const DeckLayout& a, const DeckLayout& b) {
    if (a.rowCount != b.rowCount || a.height != b.height ||
        a.groups.size() != b.groups.size()) return false;
    for (std::size_t i = 0; i < a.groups.size(); ++i) {
        const DeckGroupLayout& x = a.groups[i];
        const DeckGroupLayout& y = b.groups[i];
        if (x.id != y.id || !(x.box == y.box) || !(x.caption == y.caption)) return false;
        if (x.captionRadio.id != y.captionRadio.id || !(x.captionRadio.box == y.captionRadio.box))
            return false;
        if (!sameToggle(x.captionToggle, y.captionToggle) ||
            !sameToggle(x.captionToggle2, y.captionToggle2) ||
            !sameToggle(x.rowToggle, y.rowToggle)) return false;
        if (x.cells.size() != y.cells.size()) return false;
        for (std::size_t k = 0; k < x.cells.size(); ++k) {
            const DeckCellLayout& c = x.cells[k];
            const DeckCellLayout& d = y.cells[k];
            if (c.id != d.id || !(c.cell == d.cell) || !(c.knob == d.knob) ||
                !(c.inner == d.inner) || !(c.label == d.label)) return false;
        }
    }
    return true;
}

// A Spline excursion is fully reversible at the layout level: the mode forcing swaps the amp
// and filter faces onto their wider cells and back, leaving no residue in the geometry. Driven
// through splineActive and the editor's own forcing rule, so the deck cannot agree with a
// forcing rule the shell does not use.
static void testGateSplineGateRoundTripsToTheSameLayout() {
    PlayParams p;  // Gate, all three envelopes staged
    const DeckLayout before = layoutDeck(sampleDeckGroups(p.playMode), kPad, 0, kAvailAtMinWidth);

    p.ampSpline.mode = EnvMode::Spline;
    if (splineActive(p)) p.playMode = PlayMode::Trigger;  // editor_controls' forcing, verbatim
    CHECK(p.playMode == PlayMode::Trigger);
    const DeckLayout drawn = layoutDeck(sampleDeckGroups(p.playMode), kPad, 0, kAvailAtMinWidth);
    // The excursion is real: the amp face's cells are strictly wider than Gate's.
    const DeckGroupLayout& gateAmp =
        before.groups[static_cast<std::size_t>(indexOfGroup(sampleDeckGroups(PlayMode::Gate),
                                                            kGroupAmpEnv))];
    const DeckGroupLayout& trigAmp =
        drawn.groups[static_cast<std::size_t>(indexOfGroup(sampleDeckGroups(PlayMode::Trigger),
                                                           kGroupAmpEnv))];
    CHECK(trigAmp.cells.size() < gateAmp.cells.size());
    CHECK(trigAmp.cells[0].cell.width > gateAmp.cells[0].cell.width);
    CHECK(!sameLayout(before, drawn));

    p.ampSpline.mode = EnvMode::Staged;
    CHECK(!splineActive(p));
    p.playMode = PlayMode::Gate;  // Gate is selectable again once nothing is drawn
    const DeckLayout after = layoutDeck(sampleDeckGroups(p.playMode), kPad, 0, kAvailAtMinWidth);
    CHECK(sameLayout(before, after));
}

int main() {
    testOverlaySelectionIsExclusiveAcrossTheThreeEnvelopeDecks();
    testClickingTheActiveOverlayRadioClearsToNone();
    testANonRadioIdLeavesTheOverlaySelectionAlone();
    testOverlayIsInertExactlyWhenItsGroupToggleIsOff();
    testDeckKnobIsInertExactlyWithItsGroupsEnableToggle();
    testAModeToggleIsNeitherLiveNorAnOverlayRadio();
    testTheModeTogglesCostNoGroupWidth();
    testEveryDeckControlIsClassifiedLiveOrReloading();
    testOnlyALiveControlsDragTakesTheLiveTier();
    testDeckReadsPitchThenFilterThenAmpLeftToRight();
    testVelocityGroupOwnsTheThreeCurvesExclusively();
    testCurveTargetNamesEachCellsOwnDestination();
    testVelocityCellsHitTestWithinTheirGroup();
    testFilterGroupCarriesItsToneControlsPlusModulation();
    testOnlyTheThreeEnvelopeDecksCarryARadio();
    testGateAndTriggerFacesCarryTheirOwnShapes();
    testOnlySlopedStageKnobsCarryAnInnerCurveDial();
    testAmpGroupWidthSurvivesAGateTriggerFlip();
    testWrappedDeckHeightAtTheEditorFloorWidth();
    testDeckFitsInsideTheEnforcedMinimumWindow();
    testNoFaceLeavesSlackWhereItsDroppedControlsWere();
    testGateModeWidthsAndRowAssignmentAreUnchanged();
    testGateSplineGateRoundTripsToTheSameLayout();
    testHitTestResolvesTheNewFilterControls();
    testBipolarKnobLawRoundTripsAndIsExactAtCentre();
    if (g_fail == 0) std::printf("deck_groups: all tests passed\n");
    return g_fail == 0 ? 0 : 1;
}