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 group widths, the editor
// floor derived from the deck's width budget and each group's categorical row,
// 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: BOTH toggles now
    // ride the caption row, which is what takes the group from 524 to 432.
    CHECK(f.captionToggle.id == cell(DeckParam::kFilterEnable));
    CHECK(f.captionToggle2.id == cell(DeckParam::kFilterLaw));
    CHECK(f.rowToggle.id == -1);

    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 a SELECTABLE overlay radio, each its own, and no
// other group has one — the exclusivity the shell enforces is only meaningful if the id space
// is. MASTER occupies the same corner slot with a PASSIVE lamp, which is a different thing:
// it must never be counted as, or reachable as, a selector.
static void testOnlyTheThreeEnvelopeDecksCarryASelectableRadio() {
    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;
            if (d.captionRadio.passive) {
                CHECK(d.id == kGroupMaster);
                CHECK(d.captionRadio.id == cell(DeckParam::kMasterGr));
                // A passive slot names no overlay, so no click on it could select one even if
                // the hit-test ever handed it through.
                CHECK(overlayEnvForRadio(d.captionRadio.id) == OverlayEnv::kNone);
                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) == deckHeight(trig));
}

// TWO rows plus the spanning deck, BY CONSTRUCTION: the row count is read off the group
// inventory's own row assignment, not observed as a pack outcome, so it holds at every width.
static void testTheDeckIsTwoRowsPlusTheSpanningDeckByConstruction() {
    for (PlayMode mode : {PlayMode::Gate, PlayMode::Trigger}) {
        const std::vector<DeckGroupDesc> g = sampleDeckGroups(mode);
        CHECK(deckRowCount(g) == 2);
        CHECK(deckHeight(g) == 2 * kDeckGroupH + kDeckRowGap);
        CHECK(deckHeight(g) == 216);

        for (int avail : {kAvailAtMinWidth, kAvailAtMinWidth + 200, 4000}) {
            const DeckLayout dl = layoutDeck(g, kPad, 0, avail);
            CHECK(dl.rowCount == 2);
            CHECK(dl.height == 216);
            CHECK(dl.groups.size() == g.size());
            int rowTops[2] = {0, kDeckGroupH + kDeckRowGap};
            for (const DeckGroupLayout& gl : dl.groups) {
                const DeckRow row = deckRowFor(static_cast<DeckGroupId>(gl.id));
                if (row == DeckRow::Spanning) {
                    CHECK(gl.box.y == 0);
                    CHECK(gl.box.height == kDeckSpanningH);
                    CHECK(gl.box.right() == kPad + avail);  // right-anchored at every width
                } else {
                    CHECK(gl.box.y == rowTops[row == DeckRow::Contour ? 1 : 0]);
                    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 the floor height 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);
        const SampleBands b = computeSampleBands(kEditorMinWidth, kEditorMinHeight, h);
        CHECK(deckRowCount(g) == 2);  // either face
        CHECK(b.decks.height == h);
        // The reflow's 112 px land in the waveform: at two rows the deck band is 216 and the
        // waveform 358, against 328/246 before. Pinned now that both are reached by
        // construction rather than by a pack outcome.
        CHECK(b.decks.height == 2 * kDeckGroupH + kDeckRowGap);
        CHECK(b.waveform.height == 358);
        // 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);
    }
}

// The floor is a DERIVED number, and this is the one place the derivation is written down —
// sample_bands stays independent of knob_deck, so neither header can hold it. This fixture is
// the only one that includes both.
static void testTheEditorFloorIsDerivedFromTheDeckWidthBudget() {
    CHECK(kDeckRowBlockW + kDeckGroupGap + kDeckSpanningW + 2 * kPad == kEditorMinWidth);
    // The budget: what is left between the derived floor and the hard ceiling, and it is spent
    // once. A cell costs 60 of it.
    CHECK(kEditorCeilingWidth - kEditorMinWidth == 90);
    // The reflow's 112 px goes entirely to the waveform, so the height does not move.
    CHECK(kEditorMinHeight == 680);
    // The floor did not move to make the reflow fit — the reflow was fitted to the floor. This
    // wave spends the budget it was handed; it does not widen it.
    CHECK(kEditorMinWidth == 1190);
    CHECK(kEditorMinWidth <= kEditorCeilingWidth);
    CHECK(kEditorMinHeight <= 720);
    // And the row block really is what the two rows justify inside — derived from the floor
    // and the spanning reserve, not restated.
    CHECK(kEditorMinWidth - 2 * kPad - kDeckSpanningW - kDeckGroupGap == kDeckRowBlockW);
}

static void testEveryDeckGroupBelongsToExactlyOneRow() {
    CHECK(deckRowFor(kGroupPitch) == DeckRow::Sound);
    CHECK(deckRowFor(kGroupFilter) == DeckRow::Sound);
    CHECK(deckRowFor(kGroupVelocity) == DeckRow::Sound);
    CHECK(deckRowFor(kGroupVoice) == DeckRow::Sound);
    CHECK(deckRowFor(kGroupPitchEnv) == DeckRow::Contour);
    CHECK(deckRowFor(kGroupFilterEnv) == DeckRow::Contour);
    CHECK(deckRowFor(kGroupAmpEnv) == DeckRow::Contour);
    CHECK(deckRowFor(kGroupMaster) == DeckRow::Spanning);

    // Totality against the descriptor list the deck actually carries, not just against the
    // enum: a group that shipped without a row would land here as a miscount.
    for (PlayMode mode : {PlayMode::Gate, PlayMode::Trigger}) {
        int sound = 0, contour = 0, spanning = 0;
        for (const DeckGroupDesc& d : sampleDeckGroups(mode)) {
            switch (deckRowFor(static_cast<DeckGroupId>(d.id))) {
                case DeckRow::Sound:    ++sound;    break;
                case DeckRow::Contour:  ++contour;  break;
                case DeckRow::Spanning: ++spanning; break;
            }
        }
        CHECK(sound == 4 && contour == 3 && spanning == 1);
    }
}

// Both rows now fit their block, in BOTH play modes. Row 1's fit is the one this track closes:
// it was 1030, +42 from PITCH/RATE's third cell and −92 from FILTER's Band|Notch caption move
// take it to 980. Row 2's 876 is mode-stable because FILTER ENV's and AMP's reserve slots hold
// them at 312 in Trigger too — asserted here rather than assumed.
static void testBothRowsAndTheSpanningDeckFitTheBudget() {
    for (PlayMode mode : {PlayMode::Gate, PlayMode::Trigger}) {
        const std::vector<DeckGroupDesc> g = sampleDeckGroups(mode);
        int width[3] = {0, 0, 0};
        int count[3] = {0, 0, 0};
        for (const DeckGroupDesc& d : g) {
            const int r = static_cast<int>(deckRowFor(static_cast<DeckGroupId>(d.id)));
            width[r] += deckGroupWidth(d);
            ++count[r];
        }
        const int sound = static_cast<int>(DeckRow::Sound);
        const int contour = static_cast<int>(DeckRow::Contour);
        const int spanning = static_cast<int>(DeckRow::Spanning);

        CHECK(count[sound] == 4);
        CHECK(width[sound] == 980);   // 192 + 432 + 192 + 164
        CHECK(count[contour] == 3);
        CHECK(width[contour] == 876);  // 252 + 312 + 312
        CHECK(count[spanning] == 1);
        CHECK(width[spanning] == kDeckSpanningW);  // 142 exactly — the reserve is now spent

        for (int r : {sound, contour}) {
            CHECK(width[r] <= kDeckRowBlockW);
            // Slack enough that no gutter in the row falls under the minimum.
            CHECK(kDeckRowBlockW - width[r] >= (count[r] - 1) * kDeckGroupGap);
        }
    }
}

// The gutters the justification law produces at the floor, and the alignment they buy. The
// SPEC (instrument-control-surface.md §1.2/§1.3) states row 1 as 12/14/14 with both filter
// edges at x = 636; equal division of 40 px over three gutters cannot produce that, so what is
// pinned here is what the LAW produces — 14/13/13, filter edge 638 — with row 2 exact at
// 72/72 and 636. The 2 px is flagged for review; a row block of 1028 (floor 1198, still under
// the 1280 ceiling) is the width at which the law puts both edges on 640.
static void testGutterArithmeticAndTheFilterTieLineAtTheFloor() {
    const std::vector<DeckGroupDesc> g = sampleDeckGroups(PlayMode::Gate);
    const DeckLayout dl = layoutDeck(g, kPad, 0, kAvailAtMinWidth);

    const auto box = [&](int id) {
        return dl.groups[static_cast<std::size_t>(indexOfGroup(g, id))].box;
    };
    // Row 1: flush left, flush right on the block, gutters 14/13/13.
    CHECK(box(kGroupPitch).x == kPad);
    CHECK(box(kGroupFilter).x - box(kGroupPitch).right() == 14);
    CHECK(box(kGroupVelocity).x - box(kGroupFilter).right() == 13);
    CHECK(box(kGroupVoice).x - box(kGroupVelocity).right() == 13);
    CHECK(box(kGroupVoice).right() == kPad + kDeckRowBlockW);

    // Row 2: flush left, flush right, and its two gutters exactly equal — the property the
    // 1020 block was chosen for, and the one it does deliver.
    CHECK(box(kGroupPitchEnv).x == kPad);
    CHECK(box(kGroupFilterEnv).x - box(kGroupPitchEnv).right() == 72);
    CHECK(box(kGroupAmpEnv).x - box(kGroupFilterEnv).right() == 72);
    CHECK(box(kGroupAmpEnv).right() == kPad + kDeckRowBlockW);

    // The filter tie-line, block-relative. Row 2 lands on the specified 636; row 1 lands 2 px
    // past it. See this test's header.
    CHECK(box(kGroupFilterEnv).right() - kPad == 636);
    CHECK(box(kGroupFilter).right() - kPad == 638);

    // MASTER is right-anchored outside the block, one kDeckGroupGap clear of it.
    CHECK(box(kGroupMaster).x - box(kGroupVoice).right() == kDeckGroupGap);
    CHECK(box(kGroupMaster).right() == kPad + kAvailAtMinWidth);
}

// No gutter is ever narrower than kDeckGroupGap at or above the floor, and both rows stay
// flush at every width — the property the exact-at-the-floor numbers above are one point of.
// Above the floor the tie-line DRIFTS, which is accepted and deliberate (§1.3): row 1 divides
// its slack over three gutters and row 2 over two, so row 2's filter edge pulls right past
// row 1's and the gap widens monotonically. Encoded as EXPECTED, not as a failure.
static void testGuttersHoldTheirMinimumAndTheTieLineDriftsAboveTheFloor() {
    for (PlayMode mode : {PlayMode::Gate, PlayMode::Trigger}) {
        const std::vector<DeckGroupDesc> g = sampleDeckGroups(mode);
        int lastDrift = 1 << 20;  // sentinel above any real drift
        for (int avail = kAvailAtMinWidth; avail <= kAvailAtMinWidth + 600; avail += 37) {
            const DeckLayout dl = layoutDeck(g, kPad, 0, avail);
            const DeckGroupLayout* prev = nullptr;
            DeckRow prevRow = DeckRow::Spanning;
            for (const DeckGroupLayout& gl : dl.groups) {
                const DeckRow row = deckRowFor(static_cast<DeckGroupId>(gl.id));
                if (row != DeckRow::Spanning && prev && row == prevRow) {
                    CHECK(gl.box.x - prev->box.right() >= kDeckGroupGap);
                }
                prev = &gl;
                prevRow = row;
            }
            const auto right = [&](int id) {
                return dl.groups[static_cast<std::size_t>(indexOfGroup(g, id))].box.right();
            };
            // Flush right on the block at every width, both rows.
            CHECK(right(kGroupVoice) == right(kGroupAmpEnv));
            // Monotone in width rather than oscillating: row 2's two gutters absorb slack
            // faster than row 1's three, so the gap only ever opens.
            const int drift = right(kGroupFilter) - right(kGroupFilterEnv);
            CHECK(drift <= lastDrift);
            lastDrift = drift;
        }
        // It really does open up, and by far more than the 2 px it starts at — separation
        // above the floor is the accepted outcome, not a near-miss to be pinned back.
        CHECK(lastDrift < -50);
    }
}

// MASTER's interior, exact to the pixel (§1.4). The two left slots sit on the two rows' own
// knob baselines — that is what "stitched to both rows" means — and the meter is ONE rect
// across both, never a readout per row.
static void testTheMasterDeckInteriorLandsOnBothRowBaselines() {
    const std::vector<DeckGroupDesc> g = sampleDeckGroups(PlayMode::Gate);
    const DeckLayout dl = layoutDeck(g, kPad, 0, kAvailAtMinWidth);
    const DeckGroupLayout& m =
        dl.groups[static_cast<std::size_t>(indexOfGroup(g, kGroupMaster))];

    CHECK(m.box.width == 142);
    CHECK(m.box.height == 216);
    // 6 + 60 + 8 + 62 + 6 — the decomposition, not just the total.
    CHECK(kDeckGroupPadX + kDeckCellW + kDeckColumnGap + 62 + kDeckGroupPadX == 142);

    // One cell drawn (gain) and one slot RESERVED below it: the reserve is height at a fixed
    // position and draws nothing.
    CHECK(m.cells.size() == 1);
    CHECK(m.cells[0].id == cell(DeckParam::kMasterGain));
    CHECK(m.cells[0].cell.y - m.box.y == 26);
    const int reserveTop = m.cells[0].cell.y + kDeckGroupH + kDeckRowGap;
    CHECK(reserveTop - m.box.y == 138);

    // The two baselines are row 1's and row 2's own.
    const DeckGroupLayout& filter =
        dl.groups[static_cast<std::size_t>(indexOfGroup(g, kGroupFilter))];
    const DeckGroupLayout& amp =
        dl.groups[static_cast<std::size_t>(indexOfGroup(g, kGroupAmpEnv))];
    CHECK(m.cells[0].cell.y == filter.cells[0].cell.y);
    CHECK(reserveTop == amp.cells[0].cell.y);

    // The meter: one rect spanning both baselines, 62 x 186.
    CHECK(m.column.id == cell(DeckParam::kMasterMeter));
    CHECK(m.column.box.width == 62);
    CHECK(m.column.box.height == 186);
    CHECK(m.column.box.y == m.cells[0].cell.y);
    CHECK(m.column.box.bottom() - m.box.y == 212);
}

// The regression guard for the rule most likely to be "generalised" wrongly: MASTER's left
// column is FIXED slots at the two baselines, NOT knob_deck's horizontal run-division law
// applied vertically — which would stretch the one gain knob over the whole 186 px.
static void testTheMasterColumnDoesNotDivideItsRunVertically() {
    const std::vector<DeckGroupDesc> g = sampleDeckGroups(PlayMode::Gate);
    const DeckLayout dl = layoutDeck(g, kPad, 0, kAvailAtMinWidth);
    const DeckGroupLayout& m =
        dl.groups[static_cast<std::size_t>(indexOfGroup(g, kGroupMaster))];
    CHECK(m.cells[0].cell.height == kDeckCellH);
    CHECK(m.cells[0].cell.width == kDeckCellW);
    // Under the run-division law the lone present cell would take the whole two-slot run;
    // here it takes exactly one slot and leaves the rest empty.
    CHECK(m.cells[0].cell.height < m.column.box.height);
    CHECK(m.cells[0].cell.bottom() < m.column.box.bottom());
    CHECK(m.cells[0].knob.width == kDeckKnobSize && m.cells[0].knob.height == kDeckKnobSize);
    // And dropping the reserve does not move the gain knob or the meter — the slot below it is
    // reserved height, so nothing above it depends on whether it is there.
    std::vector<DeckGroupDesc> noReserve = g;
    for (DeckGroupDesc& d : noReserve) {
        if (d.id == kGroupMaster) d.cellIds = {cell(DeckParam::kMasterGain)};
    }
    const DeckLayout dl2 = layoutDeck(noReserve, kPad, 0, kAvailAtMinWidth);
    const DeckGroupLayout& m2 =
        dl2.groups[static_cast<std::size_t>(indexOfGroup(noReserve, kGroupMaster))];
    CHECK(m2.cells[0].cell == m.cells[0].cell);
    CHECK(m2.column.box == m.column.box);
}

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);

    // The morph law answers from its NEW home in the caption row, and as a CaptionToggle —
    // the shell's toggle branch handles both kinds, so the move must not change the id or the
    // segment either.
    const DeckHit band = hitTestDeck(dl, f.captionToggle2.seg0.x + 2,
                                     f.captionToggle2.seg0.y + 2);
    CHECK(band.kind == DeckHitKind::CaptionToggle);
    CHECK(band.id == cell(DeckParam::kFilterLaw) && band.segment == 0);
    const DeckHit notch = hitTestDeck(dl, f.captionToggle2.seg1.x + 2,
                                      f.captionToggle2.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 testEveryDeckControlIsClassifiedIntoOneOfTheThreeCommitTiers() {
    // The live set: the seven filter tone/modulation knobs, the baseline pitch offset, plus
    // every stage time, stage level, hold fraction and curve exponent on all three envelopes —
    // in BOTH mode shapes.
    const DeckParam live[] = {
        DeckParam::kPitch,
        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(deckParamCommit(p) == LiveCommit::Live);

    // The note-on-latched tier: published like a live control, read only at note-on. Asserted as
    // its OWN state rather than as "not Reload" — the whole point of widening the predicate is
    // that Rate must not fall back into either neighbour, and Γ-W4-T1 reads this classification
    // to decide what it exposes to the host.
    const DeckParam latched[] = {DeckParam::kRate};
    for (DeckParam p : latched) CHECK(deckParamCommit(p) == LiveCommit::NoteOnLatched);

    // 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, DeckParam::kLimiterEnable,
        DeckParam::kMasterMeter, DeckParam::kMasterGr,
    };
    for (DeckParam p : reloads) CHECK(deckParamCommit(p) == LiveCommit::Reload);

    // COVERAGE, not cardinality: every id appears in EXACTLY ONE of the three 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 : latched) 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() {
    // deckParamCommit 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.
    const auto knob = [](DeckParam p) {
        return liveCommitFor(LiveDragKind::kDeckKnob, static_cast<int>(p));
    };
    CHECK(knob(DeckParam::kFilterCutoff) == LiveCommit::Live);
    CHECK(knob(DeckParam::kAttack) == LiveCommit::Live);
    CHECK(knob(DeckParam::kPitch) == LiveCommit::Live);
    // The Trigger amp is live now that the fade pair folded into the AHD — the one behavioural
    // consequence of that consolidation.
    CHECK(knob(DeckParam::kTrigAttack) == LiveCommit::Live);
    CHECK(knob(DeckParam::kTrigDecayCurve) == LiveCommit::Live);
    // Rate keeps its own tier through the drag site: it must not arrive as Live (which would let
    // it move a sounding note) nor as Reload (which would re-decode the WAV under a swept knob).
    CHECK(knob(DeckParam::kRate) == LiveCommit::NoteOnLatched);
    CHECK(knob(DeckParam::kTrigLength) == LiveCommit::Reload);
    CHECK(knob(DeckParam::kMasterGain) == LiveCommit::Reload);
    CHECK(knob(DeckParam::kAmpEnvSelect) == LiveCommit::Reload);
    // 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) == LiveCommit::Reload);
    CHECK(liveCommitFor(LiveDragKind::kDeckKnob, -1) == LiveCommit::Reload);
    CHECK(knob(DeckParam::kCount) == LiveCommit::Reload);
    // Every stage value an envelope node can reach is live, in either mode shape.
    CHECK(liveCommitFor(LiveDragKind::kEnvNode, -1) == LiveCommit::Live);
    // Every other drag (markers, scrollbar, curve nodes) commits through a reload.
    CHECK(liveCommitFor(LiveDragKind::kOther, static_cast<int>(DeckParam::kFilterCutoff)) ==
          LiveCommit::Reload);
}

// --- 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(deckParamCommit(DeckParam::kAmpEnvMode) == LiveCommit::Reload);
    CHECK(deckParamCommit(DeckParam::kPitchEnvMode) == LiveCommit::Reload);
    CHECK(deckParamCommit(DeckParam::kFilterEnvMode) == LiveCommit::Reload);
    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) {
                // The spanning deck's slots STACK — the run-division law this pins is the
                // horizontal one, and its vertical guard is its own test.
                if (g[i].row == DeckRow::Spanning) continue;
                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.

// PITCH/RATE carries three cells and measures exactly 192 — the KNOB row (3 x kDeckCellW plus
// padding) is what it measures from, and the caption row must stay under that. The ceiling is
// asserted by construction rather than as a comment: at a caption reserve of 80 the group is
// still 192, and at 81 it is not, which is the whole content of "hard ceiling 80". Widening the
// group is not the remedy if the caption text ever outgrows it — narrowing the mode toggle is.
static void testThePitchRateGroupIsKnobRowDrivenAtExactlyOneNinetyTwo() {
    const std::vector<DeckGroupDesc> g = sampleDeckGroups(PlayMode::Gate);
    const DeckGroupDesc* pitch = nullptr;
    for (const DeckGroupDesc& d : g) if (d.id == kGroupPitch) pitch = &d;
    CHECK(pitch != nullptr);
    if (!pitch) return;
    CHECK(pitch->cellIds.size() == 3);
    CHECK(pitch->cellIds[0] == static_cast<int>(DeckParam::kKeyTrack));
    CHECK(pitch->cellIds[1] == static_cast<int>(DeckParam::kRate));
    CHECK(pitch->cellIds[2] == static_cast<int>(DeckParam::kPitch));
    CHECK(deckGroupWidth(*pitch) == 192);
    CHECK(3 * kDeckCellW + 2 * kDeckGroupPadX == 192);  // the knob row IS the measurement

    DeckGroupDesc probe = *pitch;
    probe.captionWidth = 80;
    CHECK(deckGroupWidth(probe) == 192);  // at the ceiling the caption row still fits under it
    probe.captionWidth = 81;
    CHECK(deckGroupWidth(probe) > 192);   // one past it, the caption row takes over
}

// Every group's width, in BOTH play modes, against the measured layout table
// (instrument-control-surface.md §1.2). Mode-independence is the second half of the claim: the
// reserve slots hold the two mode-dependent groups at 312 either way, which is what makes the
// contour row's 876 a constant rather than a Gate-only fact.
static void testEveryGroupWidthMatchesTheMeasuredLayout() {
    const struct { int id; int width; } want[] = {
        {kGroupPitch, 192}, {kGroupPitchEnv, 252}, {kGroupFilter, 432},
        {kGroupFilterEnv, 312}, {kGroupAmpEnv, 312}, {kGroupVelocity, 192},
        {kGroupVoice, 164}, {kGroupMaster, 142},
    };
    for (PlayMode mode : {PlayMode::Gate, PlayMode::Trigger}) {
        const std::vector<DeckGroupDesc> g = sampleDeckGroups(mode);
        CHECK(g.size() == sizeof(want) / sizeof(want[0]));
        const DeckLayout dl = layoutDeck(g, kPad, 0, kAvailAtMinWidth);
        for (const auto& w : want) {
            const int i = indexOfGroup(g, w.id);
            CHECK(i >= 0);
            if (i < 0) continue;
            CHECK(deckGroupWidth(g[static_cast<std::size_t>(i)]) == w.width);
            const DeckGroupLayout& lay =
                dl.groups[static_cast<std::size_t>(indexOfGroup(g, w.id))];
            CHECK(lay.box.width == w.width);
        }
        // Gate carries no reserves, so its cells are the deck's base size; Trigger's two
        // reduced faces divide the same reserved run between fewer cells and get wider ones.
        for (const DeckGroupLayout& lay : dl.groups) {
            for (const DeckCellLayout& c : lay.cells) {
                CHECK(c.cell.width >= kDeckCellW);
                if (mode == PlayMode::Gate) 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) ||
            x.captionRadio.passive != y.captionRadio.passive) return false;
        if (x.column.id != y.column.id || !(x.column.box == y.column.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 the shared enforceGateUnavailableWhileDrawn helper, so the deck cannot agree with a
// forcing rule the real callers do 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;
    enforceGateUnavailableWhileDrawn(p);  // the shared helper both real callers route through
    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();
    testEveryDeckControlIsClassifiedIntoOneOfTheThreeCommitTiers();
    testOnlyALiveControlsDragTakesTheLiveTier();
    testDeckReadsPitchThenFilterThenAmpLeftToRight();
    testVelocityGroupOwnsTheThreeCurvesExclusively();
    testCurveTargetNamesEachCellsOwnDestination();
    testVelocityCellsHitTestWithinTheirGroup();
    testFilterGroupCarriesItsToneControlsPlusModulation();
    testOnlyTheThreeEnvelopeDecksCarryASelectableRadio();
    testGateAndTriggerFacesCarryTheirOwnShapes();
    testOnlySlopedStageKnobsCarryAnInnerCurveDial();
    testAmpGroupWidthSurvivesAGateTriggerFlip();
    testTheDeckIsTwoRowsPlusTheSpanningDeckByConstruction();
    testDeckFitsInsideTheEnforcedMinimumWindow();
    testNoFaceLeavesSlackWhereItsDroppedControlsWere();
    testThePitchRateGroupIsKnobRowDrivenAtExactlyOneNinetyTwo();
    testEveryGroupWidthMatchesTheMeasuredLayout();
    testGateSplineGateRoundTripsToTheSameLayout();
    testTheEditorFloorIsDerivedFromTheDeckWidthBudget();
    testEveryDeckGroupBelongsToExactlyOneRow();
    testBothRowsAndTheSpanningDeckFitTheBudget();
    testGutterArithmeticAndTheFilterTieLineAtTheFloor();
    testGuttersHoldTheirMinimumAndTheTieLineDriftsAboveTheFloor();
    testTheMasterDeckInteriorLandsOnBothRowBaselines();
    testTheMasterColumnDoesNotDivideItsRunVertically();
    testHitTestResolvesTheNewFilterControls();
    testBipolarKnobLawRoundTripsAndIsExactAtCentre();
    if (g_fail == 0) std::printf("deck_groups: all tests passed\n");
    return g_fail == 0 ? 0 : 1;
}