libdpf/test/tests/stress_scenarios_test.cpp

// Stress scenarios that exercise BOTH classic-shaped and multilevel/cmp DPF
// keys through the unified eval surface. The intent is to give the classic
// (single-level, equal-width) and multilevel (per-slot `at<N>` + `cmp`) code
// paths symmetric coverage: everything the multilevel surface can do is also
// checked on classic keys, and every classic strength (Doerner-Shelat parity,
// inner product, memoizer variants, recipe modes) is checked on multilevel
// keys where it applies.
//
// Patterns (recon xor-vs-additive, DS tape/roots harness) mirror
// incremental_test.cpp.

#include <gtest/gtest.h>

#include "dpf.hpp"
#include "grotto/fixedpoint.hpp"

#include <algorithm>
#include <array>
#include <cstdint>
#include <cstdlib>
#include <cstring>
#include <type_traits>
#include <vector>

namespace
{

// ---------------------------------------------------------------------------
// Deterministic randomness harness (roots + pad tape), copied from
// incremental_test.cpp so dealer <-> Doerner-Shelat byte-identity holds.
// ---------------------------------------------------------------------------

simde__m128i g_roots[16];
int g_ri = 0;
simde__m128i take_root() { return g_roots[g_ri++]; }

std::vector<unsigned char> g_tape(1 << 18);
std::size_t g_ti = 0;
void tape_fill(void * p, std::size_t n)
{
    if (g_ti + n > g_tape.size())
        std::abort();
    std::memcpy(p, g_tape.data() + g_ti, n);
    g_ti += n;
}

struct PadA
{
    uint64_t n = 1;
    simde__m128i block()
    {
        auto v = simde_mm_set_epi64x(static_cast<long long>(n),
            static_cast<long long>(n * 9 + 3));
        n += 2;
        return v;
    }
    uint8_t bit() { return static_cast<uint8_t>(n++ & 1u); }
};

void reset_tape_roots()
{
    g_ri = 0;
    g_ti = 0;
}

void seed_fixed_rng()
{
    for (int i = 0; i < 16; ++i)
        g_roots[i] = simde_mm_set_epi64x(0x2222 * (i + 1), 0xBEEF0000u + i * 23);
    for (std::size_t i = 0; i < g_tape.size(); ++i)
        g_tape[i] = static_cast<unsigned char>(i * 31 + 7);
}

bool same_bytes(const void * a, const void * b, std::size_t n)
{
    return std::memcmp(a, b, n) == 0;
}

template <typename T>
constexpr bool is_xor_out_v =
    std::is_same_v<T, dpf::bit> || dpf::utils::is_xor_wrapper_v<T>;

template <typename A, typename B>
auto recon(const A & a, const B & b)
{
    if constexpr (dpf::is_secret_share_v<A> && dpf::is_secret_share_v<B>)
        return dpf::reconstruct(a, b);
    else if constexpr (is_xor_out_v<A>)
        return static_cast<A>(a ^ b);
    else
        return static_cast<A>(a - b);  // subtractive: party0 - party1
}

/// Flip the low bit of the N-bit MSB prefix (neighbor lane for packed leaves).
template <typename InputT>
InputT flip_lane_lsb(InputT x, std::size_t prefix, std::size_t bitlen)
{
    return static_cast<InputT>(x ^ (InputT{1} << (bitlen - prefix)));
}

// ---------------------------------------------------------------------------
// Byte-identity helpers (classic + incremental) copied from incremental_test.
// ---------------------------------------------------------------------------

template <typename Key, std::size_t I = 0>
bool same_leaf_beaver(const Key & a, const Key & b)
{
    if constexpr (I < Key::num_outputs)
    {
        const auto & la = a.template leaf<I>();
        const auto & lb = b.template leaf<I>();
        if (!same_bytes(&la, &lb, sizeof(la)))
            return false;
        const auto & ba = a.template beaver<I>();
        const auto & bb = b.template beaver<I>();
        using out_t = typename Key::template output_type_t<I>;
        if constexpr (dpf::is_wildcard_v<out_t>)
        {
            return same_bytes(&ba.output_blind, &bb.output_blind,
                       sizeof(ba.output_blind))
                && same_bytes(&ba.vector_blind, &bb.vector_blind,
                       sizeof(ba.vector_blind))
                && same_bytes(&ba.blinded_vector, &bb.blinded_vector,
                       sizeof(ba.blinded_vector))
                && same_leaf_beaver<Key, I + 1>(a, b);
        }
        return same_bytes(&ba, &bb, sizeof(ba))
            && same_leaf_beaver<Key, I + 1>(a, b);
    }
    return true;
}

// Byte-for-byte comparison of the comparison (DCF) channel: metadata,
// value-CW array, `cw_last`, and this party's `cmp_addend` share. All four
// carry the secret comparison payload / threshold, so a dealer key and a
// Doerner-Shelat key must agree on every byte here (not merely reconstruct).
template <typename Key>
bool same_cmp_channel(const Key & a, const Key & b)
{
    if (a.has_cmp() != b.has_cmp())
        return false;
    if (!a.has_cmp())
        return true;
    const auto & ca = a.cmp();
    const auto & cb = b.cmp();
    if (ca.nbits != cb.nbits || ca.mask != cb.mask || ca.kind != cb.kind
        || ca.trivial != cb.trivial || ca.eval_as_ge != cb.eval_as_ge
        || ca.include_eq != cb.include_eq || ca.active != cb.active
        || ca.incremental != cb.incremental)
        return false;
    using word = typename Key::value_cw_word;
    if (!same_bytes(a.value_cw().data(), b.value_cw().data(),
            sizeof(word) * a.value_cw().size()))
        return false;
    if (a.cw_last() != b.cw_last())
        return false;
    if (a.cmp_addend() != b.cmp_addend())
        return false;
    return true;
}

// Element-wise byte comparison of the public `if_false` addends (from eq()).
// Wildcard-typed elements are not byte-comparable and are skipped.
template <typename Key, std::size_t I = 0>
bool same_public_addends(const Key & a, const Key & b)
{
    if constexpr (I < std::tuple_size_v<typename Key::addend_tuple>)
    {
        using elem_t = std::tuple_element_t<I, typename Key::addend_tuple>;
        if constexpr (!dpf::is_wildcard_v<elem_t>)
        {
            const auto & ea = std::get<I>(a.public_addends);
            const auto & eb = std::get<I>(b.public_addends);
            if (!same_bytes(&ea, &eb, sizeof(ea)))
                return false;
        }
        return same_public_addends<Key, I + 1>(a, b);
    }
    return true;
}

template <typename Key>
bool same_incr_key(const Key & a, const Key & b)
{
    return same_bytes(&a.root(), &b.root(), sizeof(a.root()))
        && same_bytes(a.correction_words().data(), b.correction_words().data(),
            sizeof(a.correction_words()))
        && same_bytes(a.correction_advice().data(), b.correction_advice().data(),
            sizeof(a.correction_advice()))
        && same_leaf_beaver(a, b)
        && same_cmp_channel(a, b)
        && same_public_addends(a, b);
}

template <typename Key, std::size_t I = 0>
bool same_leaf_beaver_classic(const Key & a, const Key & b)
{
    if constexpr (I < std::tuple_size_v<typename Key::outputs_tuple>)
    {
        const auto & la = a.template leaf<I>();
        const auto & lb = b.template leaf<I>();
        if (!same_bytes(&la, &lb, sizeof(la)))
            return false;
        const auto & ba = a.template beaver<I>();
        const auto & bb = b.template beaver<I>();
        using out_t = typename Key::template output_type_t<I>;
        if constexpr (dpf::is_wildcard_v<out_t>)
        {
            return same_bytes(&ba.output_blind, &bb.output_blind,
                       sizeof(ba.output_blind))
                && same_bytes(&ba.vector_blind, &bb.vector_blind,
                       sizeof(ba.vector_blind))
                && same_bytes(&ba.blinded_vector, &bb.blinded_vector,
                       sizeof(ba.blinded_vector))
                && same_leaf_beaver_classic<Key, I + 1>(a, b);
        }
        return same_bytes(&ba, &bb, sizeof(ba))
            && same_leaf_beaver_classic<Key, I + 1>(a, b);
    }
    return true;
}

template <typename Key>
bool same_classic_key(const Key & a, const Key & b)
{
    if (!same_bytes(&a.root(), &b.root(), sizeof(a.root())))
        return false;
    if (!same_bytes(a.correction_words().data(), b.correction_words().data(),
            sizeof(a.correction_words())))
        return false;
    if (!same_bytes(a.correction_advice().data(), b.correction_advice().data(),
            sizeof(a.correction_advice())))
        return false;
    return same_leaf_beaver_classic(a, b);
}

/// In-process Beaver completion for a wildcard leaf (same messages as asio
/// `assign_wildcard_output`, without a socket).
template <std::size_t I, typename Key0, typename Key1, typename ShareT>
void assign_wildcard_leaf_local(Key0 & k0, Key1 & k1, const ShareT & shr0,
    const ShareT & shr1)
{
    auto & w0 = std::get<I>(k0.leaf_nodes);
    auto & w1 = std::get<I>(k1.leaf_nodes);
    const auto b0 = w0.compute_and_get_blinded_output_share(shr0);
    const auto b1 = w1.compute_and_get_blinded_output_share(shr1);
    const auto l0 = w0.compute_and_get_leaf_share(b1);
    const auto l1 = w1.compute_and_get_leaf_share(b0);
    w0.reconstruct_correction_word(l1);
    w1.reconstruct_correction_word(l0);
}

}  // namespace

class StressScenariosTest : public ::testing::Test
{
  protected:
    void SetUp() override
    {
        seed_fixed_rng();
        dpf::detail::uniform_bytes_hook = tape_fill;
        reset_tape_roots();
    }
    void TearDown() override
    {
        dpf::detail::uniform_bytes_hook = nullptr;
    }
};

// ===========================================================================
// A) Multilevel parity with the classic surface.
// ===========================================================================

TEST_F(StressScenariosTest, MlEvalFullPrefixSlot)
{
    uint16_t x = 0xa5c3;
    auto [k0, k1] = dpf::make_dpf(x, dpf::at<8>(uint8_t{42}), dpf::at<12>(uint16_t{7}));
    constexpr std::size_t N = 8, I = 0;
    auto [b0, it0] = dpf::eval_full(dpf::out<I, N>, k0);
    auto [b1, it1] = dpf::eval_full(dpf::out<I, N>, k1);
    (void)it0; (void)it1;

    const std::size_t lane = x >> (16 - N);
    EXPECT_EQ(recon(b0[lane], b1[lane]),
        recon(*dpf::eval_point(dpf::out<I, N>, k0, x),
            *dpf::eval_point(dpf::out<I, N>, k1, x)));
    EXPECT_EQ(recon(b0[lane], b1[lane]), uint8_t{42});

    // Neighbouring lane in the same node is zero.
    const std::size_t nb = lane ^ 1u;
    EXPECT_EQ(recon(b0[nb], b1[nb]), uint8_t{0});
}

TEST_F(StressScenariosTest, MlEvalFullDeepestSlot)
{
    uint16_t x = 0x1234;
    auto [k0, k1] = dpf::make_dpf(x, dpf::at<8>(uint8_t{9}), dpf::at<12>(uint16_t{0xbeef}));
    using KT = std::decay_t<decltype(k0)>;
    constexpr std::size_t I = KT::deepest_output;
    static_assert(KT::meta[I].prefix == 12, "deepest prefix expected 12");
    constexpr std::size_t N = 12;
    auto [b0, it0] = dpf::eval_full(dpf::out<I, N>, k0);
    auto [b1, it1] = dpf::eval_full(dpf::out<I, N>, k1);
    (void)it0; (void)it1;

    const std::size_t lane = x >> (16 - N);
    EXPECT_EQ(recon(b0[lane], b1[lane]),
        recon(*dpf::eval_point(dpf::out<I, N>, k0, x),
            *dpf::eval_point(dpf::out<I, N>, k1, x)));
    EXPECT_EQ(recon(b0[lane], b1[lane]), uint16_t{0xbeef});
}

TEST_F(StressScenariosTest, MlEvalFullOutbufMatchesReturned)
{
    uint16_t x = 0x7788;
    auto [k0, k1] = dpf::make_dpf(x, dpf::at<8>(uint16_t{123}), uint32_t{5});
    constexpr std::size_t N = 8, I = 0;

    auto [b0, it0] = dpf::eval_full(dpf::out<I, N>, k0);
    (void)it0;
    auto memo = dpf::make_basic_interval_memoizer<std::decay_t<decltype(k0)>, I>(
        uint16_t{0}, static_cast<uint16_t>((1u << N) - 1));
    auto ob0 = dpf::make_output_buffer(dpf::out<I, N>, k0, uint16_t{0},
        static_cast<uint16_t>((1u << N) - 1));
    dpf::eval_full(dpf::out<I, N>, k0, ob0, memo);
    for (std::size_t i = 0; i < (1u << N); ++i)
        EXPECT_EQ(ob0[i], b0[i]) << "i=" << i;
}

TEST_F(StressScenariosTest, MlEvalFullCmpSmallDomain)
{
    uint16_t alpha = 0x8000u;
    auto [k0, k1] = dpf::make_dpf(alpha, dpf::lt_at<8>(uint64_t{5}, uint64_t{1}));
    ASSERT_TRUE(k0.has_cmp());
    const uint64_t mask = k0.cmp().mask;

    auto b0 = dpf::eval_full(dpf::cmp, k0);
    auto b1 = dpf::eval_full(dpf::cmp, k1);
    ASSERT_EQ(b0.size(), std::size_t{256});

    for (std::size_t lane : {std::size_t{0x00}, std::size_t{0x7f}, std::size_t{0x80},
             std::size_t{0x81}, std::size_t{0xff}})
    {
        const uint16_t q = static_cast<uint16_t>(lane << 8);
        const uint64_t from_full =
            dpf::reconstruct(dpf::eval_point(dpf::cmp, k0, q), dpf::eval_point(dpf::cmp, k1, q)) & mask;
        EXPECT_EQ(recon(b0[lane], b1[lane]) & mask, from_full) << "lane=" << lane;
    }
    // top8(alpha)=0x80 => lanes below are lt (5), at/above are !lt (1).
    EXPECT_EQ(recon(b0[0x7f], b1[0x7f]) & mask, 5u);
    EXPECT_EQ(recon(b0[0x80], b1[0x80]) & mask, 1u);
}

TEST_F(StressScenariosTest, MlIntervalWithBasicIntervalMemoizer)
{
    uint16_t x = 0x33aa;
    auto [k0, k1] = dpf::make_dpf(x, dpf::at<12>(uint8_t{77}), uint32_t{9});
    using KT = std::decay_t<decltype(k0)>;
    constexpr std::size_t N = 12, I = 0;

    const uint16_t lane = x >> (16 - N);
    const uint16_t from = static_cast<uint16_t>(lane & ~uint16_t{0xf});
    const uint16_t to = static_cast<uint16_t>(from + 0xf);

    auto memo0 = dpf::make_basic_interval_memoizer<KT, I>(from, to);
    auto buf0 = dpf::make_output_buffer(dpf::out<I, N>, k0, from, to);
    auto buf1 = dpf::make_output_buffer(dpf::out<I, N>, k1, from, to);
    dpf::eval_interval(dpf::out<I, N>, k0, from, to, buf0, memo0);
    auto memo1 = dpf::make_basic_interval_memoizer<KT, I>(from, to);
    dpf::eval_interval(dpf::out<I, N>, k1, from, to, buf1, memo1);

    const std::size_t idx = static_cast<std::size_t>(lane - from);
    EXPECT_EQ(recon(buf0[idx], buf1[idx]),
        recon(*dpf::eval_point(dpf::out<I, N>, k0, x),
            *dpf::eval_point(dpf::out<I, N>, k1, x)));
    EXPECT_EQ(recon(buf0[idx], buf1[idx]), uint8_t{77});
    const std::size_t nbi = static_cast<std::size_t>((lane ^ 1u) - from);
    EXPECT_EQ(recon(buf0[nbi], buf1[nbi]), uint8_t{0});
}

TEST_F(StressScenariosTest, MlSequencePointLoopVsBreadthFirst)
{
    uint16_t x = 0x5a3c;
    auto [k0, k1] = dpf::make_dpf(x, dpf::at<10>(uint8_t{21}), uint32_t{99});
    constexpr std::size_t N = 10, I = 0;
    const uint16_t xlane = x >> (16 - N);

    std::vector<uint16_t> lanes = {
        static_cast<uint16_t>(xlane & ~uint16_t{0xf}), xlane,
        static_cast<uint16_t>(xlane ^ 1u),
        static_cast<uint16_t>((xlane + 3u) & 0x3ffu),
        static_cast<uint16_t>((xlane + 100u) & 0x3ffu)};
    std::sort(lanes.begin(), lanes.end());
    lanes.erase(std::unique(lanes.begin(), lanes.end()), lanes.end());

    auto bf0 = dpf::eval_sequence_breadth_first(dpf::out<I, N>, k0,
        lanes.begin(), lanes.end());
    auto bf1 = dpf::eval_sequence_breadth_first(dpf::out<I, N>, k1,
        lanes.begin(), lanes.end());

    for (std::size_t i = 0; i < lanes.size(); ++i)
    {
        const uint16_t q = static_cast<uint16_t>(lanes[i] << (16 - N));
        EXPECT_EQ(recon(bf0[i], bf1[i]),
            recon(*dpf::eval_point(dpf::out<I, N>, k0, q),
                *dpf::eval_point(dpf::out<I, N>, k1, q))) << "i=" << i;
    }
}

TEST_F(StressScenariosTest, MlSequenceRecipeDepthAndBreadthFirst)
{
    uint16_t x = 0x2b70;
    auto [k0, k1] = dpf::make_dpf(x, dpf::at<12>(uint8_t{55}), uint32_t{7});
    using KT = std::decay_t<decltype(k0)>;
    constexpr std::size_t N = 12, I = 0;

    const uint16_t lane = x >> (16 - N);
    std::array<uint16_t, 3> pts{{
        static_cast<uint16_t>(lane & ~uint16_t{1}), lane,
        static_cast<uint16_t>((lane & ~uint16_t{1}) + 1u)}};
    std::sort(pts.begin(), pts.end());

    auto recipe = dpf::make_sequence_recipe(dpf::out<I, N>, k0,
        pts.begin(), pts.end());
    EXPECT_EQ(recipe.depth(), KT::meta[I].tree_level);
    EXPECT_EQ(recipe.output_indices().size(), pts.size());

    auto b0 = dpf::eval_sequence_breadth_first(dpf::out<I, N>, k0,
        pts.begin(), pts.end());
    auto b1 = dpf::eval_sequence_breadth_first(dpf::out<I, N>, k1,
        pts.begin(), pts.end());
    for (std::size_t i = 0; i < pts.size(); ++i)
    {
        const uint16_t q = static_cast<uint16_t>(pts[i] << (16 - N));
        EXPECT_EQ(recon(b0[i], b1[i]),
            recon(*dpf::eval_point(dpf::out<I, N>, k0, q),
                *dpf::eval_point(dpf::out<I, N>, k1, q)));
    }
}

// A canonical mixed XOR+additive multilevel key reused across several tests.
namespace
{
auto make_mixed_ml(uint16_t x)
{
    return dpf::make_dpf(x,
        dpf::at<8>(uint8_t{3}, dpf::xor_wrapper<uint16_t>{0xcafe}),
        dpf::at<12>(uint32_t{123456}),
        dpf::lt_at<8>(uint64_t{9}));
}
}  // namespace

TEST_F(StressScenariosTest, MlMixedPointRecon)
{
    uint16_t x = 0x9c40;
    auto [k0, k1] = make_mixed_ml(x);
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 8>, k0, x),
                  *dpf::eval_point(dpf::out<0, 8>, k1, x)), uint8_t{3});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<1, 8>, k0, x),
                  *dpf::eval_point(dpf::out<1, 8>, k1, x)),
        dpf::xor_wrapper<uint16_t>{0xcafe});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<2, 12>, k0, x),
                  *dpf::eval_point(dpf::out<2, 12>, k1, x)), uint32_t{123456});
    // Off-prefix additive slot is zero (flip a bit inside the 12-bit prefix).
    const uint16_t off = flip_lane_lsb<uint16_t>(x, 12, 16);
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<2, 12>, k0, off),
                  *dpf::eval_point(dpf::out<2, 12>, k1, off)), uint32_t{0});
}

TEST_F(StressScenariosTest, MlMixedIntervalRecon)
{
    uint16_t x = 0x9c40;
    auto [k0, k1] = make_mixed_ml(x);
    constexpr std::size_t N = 8, I = 0;
    const uint16_t lane = x >> (16 - N);
    const uint16_t from = 0, to = 0xff;
    auto [b0, it0] = dpf::eval_interval(dpf::out<I, N>, k0, from, to);
    auto [b1, it1] = dpf::eval_interval(dpf::out<I, N>, k1, from, to);
    (void)it0; (void)it1;
    EXPECT_EQ(recon(b0[lane], b1[lane]), uint8_t{3});
    EXPECT_EQ(recon(b0[(lane + 1u) & 0xff], b1[(lane + 1u) & 0xff]), uint8_t{0});
}

TEST_F(StressScenariosTest, MlMixedSequenceRecon)
{
    uint16_t x = 0x9c40;
    auto [k0, k1] = make_mixed_ml(x);
    constexpr std::size_t N = 12, I = 2;
    std::vector<uint16_t> pts{uint16_t{0x000},
        static_cast<uint16_t>(x >> (16 - N)), uint16_t{0x400}, uint16_t{0xfff}};
    std::sort(pts.begin(), pts.end());
    pts.erase(std::unique(pts.begin(), pts.end()), pts.end());

    auto buf0 = dpf::make_output_buffer_for<I>(k0, pts.size());
    auto buf1 = dpf::make_output_buffer_for<I>(k1, pts.size());
    dpf::eval_sequence(dpf::out<I, N>, k0, pts.begin(), pts.end(), buf0);
    dpf::eval_sequence(dpf::out<I, N>, k1, pts.begin(), pts.end(), buf1);
    constexpr auto opl = std::decay_t<decltype(k0)>::template outputs_per_leaf_of<I>;
    for (std::size_t i = 0; i < pts.size(); ++i)
    {
        const uint16_t q = static_cast<uint16_t>(pts[i] << (16 - N));
        auto e0 = dpf::eval_point(dpf::out<I, N>, k0, q);
        auto e1 = dpf::eval_point(dpf::out<I, N>, k1, q);
        EXPECT_EQ(recon(buf0[i * opl + e0.offset], buf1[i * opl + e1.offset]),
            recon(*e0, *e1)) << "i=" << i;
    }
}

TEST_F(StressScenariosTest, MlMixedInnerProduct)
{
    uint16_t x = 0x9c40;
    auto [k0, k1] = make_mixed_ml(x);
    constexpr std::size_t N = 8, I = 0;  // additive u8 slot
    const uint16_t from = 0, to = 0xff;
    auto [b0, it0] = dpf::eval_interval(dpf::out<I, N>, k0, from, to);
    auto [b1, it1] = dpf::eval_interval(dpf::out<I, N>, k1, from, to);
    (void)it0; (void)it1;

    std::vector<uint64_t> w(b0.size());
    uint64_t expect = 0;
    for (std::size_t i = 0; i < w.size(); ++i)
    {
        w[i] = (i * 5u + 1u) & 0x1fu;
        expect += static_cast<uint64_t>(recon(b0[i], b1[i])) * w[i];
    }
    expect &= 0xffu;
    auto a = dpf::eval_inner_product(dpf::out<I, N>, k0, from, to, w);
    auto b = dpf::eval_inner_product(dpf::out<I, N>, k1, from, to, w);
    EXPECT_EQ(static_cast<uint8_t>(recon(a, b)), static_cast<uint8_t>(expect));
}

TEST_F(StressScenariosTest, MlMixedCmp)
{
    uint16_t x = 0x9c40;
    auto [k0, k1] = make_mixed_ml(x);
    ASSERT_TRUE(k0.has_cmp());
    EXPECT_EQ(k0.cmp().nbits, 8);
    const uint64_t mask = k0.cmp().mask;
    auto r = [&](uint16_t q) {
        return dpf::reconstruct(dpf::eval_point(dpf::cmp, k0, q), dpf::eval_point(dpf::cmp, k1, q)) & mask;
    };
    const uint16_t top = static_cast<uint16_t>((x >> 8) & 0xff);
    EXPECT_EQ(r(static_cast<uint16_t>((top - 1u) << 8)), 9u);
    EXPECT_EQ(r(static_cast<uint16_t>(top << 8)), 0u);
    EXPECT_EQ(r(static_cast<uint16_t>((top + 1u) << 8)), 0u);
}

TEST_F(StressScenariosTest, MlWildcardEvalPointThrowsBeforeAssign)
{
    uint16_t x = 0x55aa;
    dpf::wildcard_value<uint32_t> wc;
    auto [k0, k1] = dpf::make_dpf(x,
        dpf::at<8>(uint8_t{7}), dpf::at<12>(wc), uint16_t{1});
    // Slot 1 is an unassigned wildcard: evaluating it must throw.
    EXPECT_ANY_THROW((void)dpf::eval_point(dpf::out<1, 12>, k0, x));
    (void)k1;
}

TEST_F(StressScenariosTest, MlWildcardOtherSlotsStillWork)
{
    uint16_t x = 0x55aa;
    dpf::wildcard_value<uint32_t> wc;
    auto [k0, k1] = dpf::make_dpf(x,
        dpf::at<8>(uint8_t{7}), dpf::at<12>(wc), uint16_t{1});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 8>, k0, x),
                  *dpf::eval_point(dpf::out<0, 8>, k1, x)), uint8_t{7});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<2, 16>, k0, x),
                  *dpf::eval_point(dpf::out<2, 16>, k1, x)), uint16_t{1});
}

TEST_F(StressScenariosTest, MlCrossLevelPathMemoizerShallowThenDeep)
{
    uint16_t x = 0xabcd;
    auto [k0, k1] = dpf::make_dpf(x, dpf::at<8>(dpf::bit::one), uint16_t{1234});
    using KT = std::decay_t<decltype(k0)>;
    dpf::basic_path_memoizer<KT> p0{}, p1{};

    for (uint16_t q : {x, static_cast<uint16_t>(x ^ 1u),
             static_cast<uint16_t>(x ^ 0x8000u), uint16_t{0}})
    {
        auto s0 = dpf::eval_point(dpf::out<0, 8>, k0, q, p0);
        auto s1 = dpf::eval_point(dpf::out<0, 8>, k1, q, p1);
        auto d0 = dpf::eval_point(dpf::out<1, 16>, k0, q, p0);
        auto d1 = dpf::eval_point(dpf::out<1, 16>, k1, q, p1);

        auto sref = static_cast<bool>(recon(*dpf::eval_point(dpf::out<0, 8>, k0, q), *dpf::eval_point(dpf::out<0, 8>, k1, q)));
        auto dref = recon(*dpf::eval_point(dpf::out<1, 16>, k0, q),
            *dpf::eval_point(dpf::out<1, 16>, k1, q));
        EXPECT_EQ(static_cast<bool>(recon(*s0, *s1)), sref) << "q=" << q;
        EXPECT_EQ(recon(*d0, *d1), dref) << "q=" << q;
    }
}

TEST_F(StressScenariosTest, MlIndependentIntervalsTwoSlots)
{
    uint16_t x = 0x6c39;
    auto [k0, k1] = dpf::make_dpf(x,
        dpf::at<8>(uint8_t{11}), dpf::at<12>(uint16_t{2222}));
    // Slot 0 interval.
    auto [a0, ai0] = dpf::eval_interval(dpf::out<0, 8>, k0, uint16_t{0}, uint16_t{0xff});
    auto [a1, ai1] = dpf::eval_interval(dpf::out<0, 8>, k1, uint16_t{0}, uint16_t{0xff});
    (void)ai0; (void)ai1;
    // Slot 1 interval.
    auto [c0, ci0] = dpf::eval_interval(dpf::out<1, 12>, k0, uint16_t{0}, uint16_t{0xfff});
    auto [c1, ci1] = dpf::eval_interval(dpf::out<1, 12>, k1, uint16_t{0}, uint16_t{0xfff});
    (void)ci0; (void)ci1;

    EXPECT_EQ(recon(a0[x >> 8], a1[x >> 8]), uint8_t{11});
    EXPECT_EQ(recon(c0[x >> 4], c1[x >> 4]), uint16_t{2222});
}

// ===========================================================================
// B) Classic parity with multilevel strengths.
// ===========================================================================

TEST_F(StressScenariosTest, ClassicMixedByteIdenticalArgsVsConv)
{
    uint32_t x = 0x00abcdefu;
    reset_tape_roots();
    auto via_args = dpf::make_dpf(
        dpf::make_dpfargs(x, uint32_t{7}, dpf::xor_wrapper<uint32_t>{0xdeadbeef}),
        take_root);
    reset_tape_roots();
    auto via_conv = dpf::make_dpf(x,
        dpf::root_sampler_t<dpf::prg::aes128>{take_root}, uint32_t{7},
        dpf::xor_wrapper<uint32_t>{0xdeadbeef});
    EXPECT_TRUE(same_classic_key(via_args.first, via_conv.first));
    EXPECT_TRUE(same_classic_key(via_args.second, via_conv.second));
}

TEST_F(StressScenariosTest, ClassicMixedDealerMatchesDoernerShelat)
{
    uint32_t x = 0x00abcdefu;
    uint32_t x0 = 0x12345678u;
    uint32_t x1 = x ^ x0;

    reset_tape_roots();
    auto dealer = dpf::make_dpf(x,
        dpf::root_sampler_t<dpf::prg::aes128>{take_root},
        uint32_t{7}, dpf::xor_wrapper<uint32_t>{0xdeadbeef}, uint32_t{42});
    reset_tape_roots();
    dpf::ds_randomness<simde__m128i (*)(), PadA> rng{take_root, {}};
    auto ds = dpf::make_dpf_doerner_shelat(x0, x1, rng,
        uint32_t{7}, dpf::xor_wrapper<uint32_t>{0xdeadbeef}, uint32_t{42});

    // Reconstruction parity across the surface.
    for (uint32_t q : {x, x ^ 1u, 0u, 0xffffffffu})
    {
        EXPECT_EQ(recon(*dpf::eval_point<0>(dealer.first, q),
                      *dpf::eval_point<0>(dealer.second, q)),
            recon(*dpf::eval_point<0>(ds.first, q),
                *dpf::eval_point<0>(ds.second, q)));
        EXPECT_EQ(recon(*dpf::eval_point<1>(dealer.first, q),
                      *dpf::eval_point<1>(dealer.second, q)),
            recon(*dpf::eval_point<1>(ds.first, q),
                *dpf::eval_point<1>(ds.second, q)));
        EXPECT_EQ(recon(*dpf::eval_point<2>(dealer.first, q),
                      *dpf::eval_point<2>(dealer.second, q)),
            recon(*dpf::eval_point<2>(ds.first, q),
                *dpf::eval_point<2>(ds.second, q)));
    }
    EXPECT_EQ(recon(*dpf::eval_point<0>(dealer.first, x),
                  *dpf::eval_point<0>(dealer.second, x)), uint32_t{7});
    EXPECT_EQ(recon(*dpf::eval_point<2>(ds.first, x),
                  *dpf::eval_point<2>(ds.second, x)), uint32_t{42});
}

TEST_F(StressScenariosTest, ClassicInnerProductMatchesInterval)
{
    uint16_t x = 0x0abc;
    auto [k0, k1] = dpf::make_dpf(x, uint32_t{7}, uint32_t{11});
    using KT = std::decay_t<decltype(k0)>;
    const uint16_t from = 0x0a00, to = 0x0aff;

    auto [b0, it0] = dpf::eval_interval<0>(k0, from, to);
    auto [b1, it1] = dpf::eval_interval<0>(k1, from, to);
    (void)it0; (void)it1;

    std::vector<uint64_t> w(b0.size());
    uint64_t expect = 0;
    for (std::size_t i = 0; i < w.size(); ++i)
    {
        w[i] = (i * 3u + 1u) & 0xffu;
        expect += static_cast<uint64_t>(recon(b0[i], b1[i])) * w[i];
    }
    auto memo0 = dpf::make_basic_interval_memoizer<KT>(from, to);
    auto memo1 = dpf::make_basic_interval_memoizer<KT>(from, to);
    auto a = dpf::eval_inner_product<0>(k0, from, to, w, memo0);
    auto b = dpf::eval_inner_product<0>(k1, from, to, w, memo1);
    EXPECT_EQ(static_cast<uint32_t>(recon(a, b)), static_cast<uint32_t>(expect));
}

TEST_F(StressScenariosTest, ClassicOutPointMatchesIndexedPoint)
{
    uint32_t x = 0x00abcdefu;
    auto [k0, k1] = dpf::make_dpf(x, uint32_t{7}, dpf::xor_wrapper<uint32_t>{0x1234},
        uint32_t{99});
    for (uint32_t q : {x, x ^ 1u, 0u})
    {
        EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0>, k0, q),
                      *dpf::eval_point(dpf::out<0>, k1, q)),
            recon(*dpf::eval_point<0>(k0, q), *dpf::eval_point<0>(k1, q)));
        EXPECT_EQ(recon(*dpf::eval_point(dpf::out<1>, k0, q),
                      *dpf::eval_point(dpf::out<1>, k1, q)),
            recon(*dpf::eval_point<1>(k0, q), *dpf::eval_point<1>(k1, q)));
        EXPECT_EQ(recon(*dpf::eval_point(dpf::out<2>, k0, q),
                      *dpf::eval_point(dpf::out<2>, k1, q)),
            recon(*dpf::eval_point<2>(k0, q), *dpf::eval_point<2>(k1, q)));
    }
}

TEST_F(StressScenariosTest, ClassicOutIntervalMatchesIndexedInterval)
{
    uint16_t x = 0x1357;
    auto [k0, k1] = dpf::make_dpf(x, uint32_t{7}, uint32_t{9});
    const uint16_t from = 0x1300, to = 0x13ff;

    auto [b0, it0] = dpf::eval_interval(dpf::out<0, 16>, k0, from, to);
    auto [i0, i0it] = dpf::eval_interval<0>(k0, from, to);
    (void)it0; (void)i0it;
    ASSERT_EQ(b0.size(), i0.size());
    for (std::size_t i = 0; i < b0.size(); ++i)
        EXPECT_EQ(b0[i], i0[i]) << "i=" << i;
}

TEST_F(StressScenariosTest, ClassicPrepareIntervalThenInnerProduct)
{
    uint16_t x = 0x2244;
    auto [k0, k1] = dpf::make_dpf(x, uint32_t{13}, uint32_t{17});
    using KT = std::decay_t<decltype(k0)>;
    const uint16_t from = 0x2200, to = 0x22ff;

    std::vector<uint64_t> w(256);
    for (std::size_t i = 0; i < w.size(); ++i) w[i] = (i + 1u) & 0x3fu;

    auto memo0 = dpf::make_basic_interval_memoizer<KT>(from, to);
    auto memo1 = dpf::make_basic_interval_memoizer<KT>(from, to);
    dpf::eval_prepare_interval(k0, from, to, memo0);
    dpf::eval_prepare_interval(k1, from, to, memo1);
    auto a = dpf::eval_inner_product<0>(k0, from, to, w, memo0);
    auto b = dpf::eval_inner_product<0>(k1, from, to, w, memo1);

    auto memo0b = dpf::make_basic_interval_memoizer<KT>(from, to);
    auto memo1b = dpf::make_basic_interval_memoizer<KT>(from, to);
    auto a2 = dpf::eval_inner_product<0>(k0, from, to, w, memo0b);
    auto b2 = dpf::eval_inner_product<0>(k1, from, to, w, memo1b);
    EXPECT_EQ(recon(a, b), recon(a2, b2));
}

TEST_F(StressScenariosTest, ClassicPartialMisalignedInterval)
{
    uint16_t x = 0x4d17;
    auto [k0, k1] = dpf::make_dpf(x, uint32_t{31}, uint32_t{37});
    // Misaligned bounds not on leaf-node boundaries.
    const uint16_t from = 0x4d05, to = 0x4d9b;
    auto [b0, it0] = dpf::eval_interval<0>(k0, from, to);
    auto [b1, it1] = dpf::eval_interval<0>(k1, from, to);

    auto i0 = std::begin(it0);
    auto i1 = std::begin(it1);
    uint32_t cur = from;
    for (; i0 != std::end(it0); ++i0, ++i1, ++cur)
    {
        uint32_t want = (cur == x) ? 31u : 0u;
        EXPECT_EQ(static_cast<uint32_t>(recon(*i0, *i1)), want) << "cur=" << cur;
    }
    EXPECT_EQ(cur, static_cast<uint32_t>(to) + 1u);
}

TEST_F(StressScenariosTest, ClassicBasicVsFullTreeIntervalMemoizer)
{
    uint16_t x = 0x7ffe;
    auto [k0, k1] = dpf::make_dpf(x, uint32_t{101}, dpf::xor_wrapper<uint32_t>{0xbeef});
    using KT = std::decay_t<decltype(k0)>;
    const uint16_t from = 0x7f00, to = 0x7fff;

    auto mb0 = dpf::make_basic_interval_memoizer<KT>(from, to);
    auto mb1 = dpf::make_basic_interval_memoizer<KT>(from, to);
    auto [b0, bit0] = dpf::eval_interval<0>(k0, from, to, mb0);
    auto [b1, bit1] = dpf::eval_interval<0>(k1, from, to, mb1);
    (void)bit0; (void)bit1;

    auto mf0 = dpf::make_full_tree_interval_memoizer<KT>(from, to);
    auto mf1 = dpf::make_full_tree_interval_memoizer<KT>(from, to);
    auto [f0, fit0] = dpf::eval_interval<0>(k0, from, to, mf0);
    auto [f1, fit1] = dpf::eval_interval<0>(k1, from, to, mf1);
    (void)fit0; (void)fit1;

    ASSERT_EQ(b0.size(), f0.size());
    for (std::size_t i = 0; i < b0.size(); ++i)
    {
        EXPECT_EQ(recon(b0[i], b1[i]), recon(f0[i], f1[i])) << "i=" << i;
    }
}

TEST_F(StressScenariosTest, ClassicMultiLeafFullEvalPerSlot)
{
    uint8_t x = 0x2a;
    auto [k0, k1] = dpf::make_dpf(x, uint32_t{5}, uint32_t{6}, uint32_t{7});
    auto [b0, it0] = dpf::eval_full<1>(k0);
    auto [b1, it1] = dpf::eval_full<1>(k1);
    (void)it0; (void)it1;
    ASSERT_EQ(b0.size(), std::size_t{256});
    for (std::size_t i = 0; i < 256; ++i)
    {
        uint32_t want = (static_cast<uint8_t>(i) == x) ? 6u : 0u;
        EXPECT_EQ(static_cast<uint32_t>(recon(b0[i], b1[i])), want) << "i=" << i;
    }
}

// ===========================================================================
// C) Weird PRG / exotic input & packing.
// ===========================================================================

TEST_F(StressScenariosTest, PrgAesInteriorLowmcExteriorClassicPoint)
{
    uint8_t x = 0x2a;
    auto [k0, k1] = dpf::make_dpf<dpf::prg::aes128, dpf::prg::lowmc128>(x, uint32_t{0x01020304});
    for (int i = 0; i < 256; ++i)
    {
        auto s = recon(*dpf::eval_point(k0, static_cast<uint8_t>(i)),
            *dpf::eval_point(k1, static_cast<uint8_t>(i)));
        EXPECT_EQ(static_cast<uint32_t>(s),
            static_cast<uint8_t>(i) == x ? 0x01020304u : 0u);
    }
}

TEST_F(StressScenariosTest, PrgLowmcInteriorAesExteriorClassicPoint)
{
    uint8_t x = 0x91;
    auto [k0, k1] = dpf::make_dpf<dpf::prg::lowmc128, dpf::prg::aes128>(x, uint32_t{0xdeadbeef});
    for (int i = 0; i < 256; ++i)
    {
        auto s = recon(*dpf::eval_point(k0, static_cast<uint8_t>(i)),
            *dpf::eval_point(k1, static_cast<uint8_t>(i)));
        EXPECT_EQ(static_cast<uint32_t>(s),
            static_cast<uint8_t>(i) == x ? 0xdeadbeefu : 0u);
    }
}

TEST_F(StressScenariosTest, PrgAesLowmcMultilevelPoint)
{
    uint16_t x = 0x3c5a;
    auto [k0, k1] = dpf::make_dpf<dpf::prg::aes128, dpf::prg::lowmc128>(x,
        dpf::at<8>(uint8_t{42}), uint16_t{7});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 8>, k0, x),
                  *dpf::eval_point(dpf::out<0, 8>, k1, x)), uint8_t{42});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<1, 16>, k0, x),
                  *dpf::eval_point(dpf::out<1, 16>, k1, x)), uint16_t{7});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<1, 16>, k0, x ^ 1u),
                  *dpf::eval_point(dpf::out<1, 16>, k1, x ^ 1u)), uint16_t{0});
}

TEST_F(StressScenariosTest, PrgLowmcAesMultilevelPoint)
{
    uint16_t x = 0xd4e1;
    auto [k0, k1] = dpf::make_dpf<dpf::prg::lowmc128, dpf::prg::aes128>(x,
        dpf::at<10>(uint16_t{321}), uint32_t{654});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 10>, k0, x),
                  *dpf::eval_point(dpf::out<0, 10>, k1, x)), uint16_t{321});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<1, 16>, k0, x),
                  *dpf::eval_point(dpf::out<1, 16>, k1, x)), uint32_t{654});
}

TEST_F(StressScenariosTest, PrgDummyAesClassicPoint)
{
    uint8_t x = 0x40;
    auto [k0, k1] = dpf::make_dpf<dpf::prg::dummy, dpf::prg::aes128>(x, uint32_t{12345});
    for (int i = 0; i < 256; ++i)
    {
        auto s = recon(*dpf::eval_point(k0, static_cast<uint8_t>(i)),
            *dpf::eval_point(k1, static_cast<uint8_t>(i)));
        EXPECT_EQ(static_cast<uint32_t>(s),
            static_cast<uint8_t>(i) == x ? 12345u : 0u) << "i=" << i;
    }
}

TEST_F(StressScenariosTest, PrgChachaInteriorAesExteriorClassicPoint)
{
    uint8_t x = 0x2a;
    auto [k0, k1] = dpf::make_dpf<dpf::prg::chacha20, dpf::prg::aes128>(x, uint32_t{0x01020304});
    for (int i = 0; i < 256; ++i)
    {
        auto s = recon(*dpf::eval_point(k0, static_cast<uint8_t>(i)),
            *dpf::eval_point(k1, static_cast<uint8_t>(i)));
        EXPECT_EQ(static_cast<uint32_t>(s),
            static_cast<uint8_t>(i) == x ? 0x01020304u : 0u);
    }
}

TEST_F(StressScenariosTest, PrgAesInteriorChachaExteriorClassicPoint)
{
    uint8_t x = 0x91;
    auto [k0, k1] = dpf::make_dpf<dpf::prg::aes128, dpf::prg::chacha20>(x, uint32_t{0xdeadbeef});
    for (int i = 0; i < 256; ++i)
    {
        auto s = recon(*dpf::eval_point(k0, static_cast<uint8_t>(i)),
            *dpf::eval_point(k1, static_cast<uint8_t>(i)));
        EXPECT_EQ(static_cast<uint32_t>(s),
            static_cast<uint8_t>(i) == x ? 0xdeadbeefu : 0u);
    }
}

TEST_F(StressScenariosTest, PrgLowmcLowmcMultilevelPacking)
{
    uint16_t x = 0x4c1d;
    auto [k0, k1] = dpf::make_dpf<dpf::prg::lowmc128>(x,
        dpf::at<12>(uint8_t{1}, uint8_t{2}, uint8_t{3}, uint8_t{4},
            uint8_t{5}, uint8_t{6}, uint8_t{7}, uint8_t{8}),
        uint32_t{999});
    using KT = std::decay_t<decltype(k0)>;
    EXPECT_EQ(KT::meta[0].group_id, KT::meta[7].group_id);
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 12>, k0, x),
                  *dpf::eval_point(dpf::out<0, 12>, k1, x)), uint8_t{1});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<7, 12>, k0, x),
                  *dpf::eval_point(dpf::out<7, 12>, k1, x)), uint8_t{8});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<8, 16>, k0, x),
                  *dpf::eval_point(dpf::out<8, 16>, k1, x)), uint32_t{999});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 12>, k0, flip_lane_lsb(x, 12, 16)),
                  *dpf::eval_point(dpf::out<0, 12>, k1, flip_lane_lsb(x, 12, 16))),
        uint8_t{0});
}

TEST_F(StressScenariosTest, SignedInputAtAndCmp)
{
    int16_t x = -1234;
    auto [k0, k1] = dpf::make_dpf(x, dpf::at<8>(uint8_t{5}), dpf::lt(uint64_t{42}));
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 8>, k0, x),
                  *dpf::eval_point(dpf::out<0, 8>, k1, x)), uint8_t{5});
    ASSERT_TRUE(k0.has_cmp());
    const uint64_t mask = k0.cmp().mask;
    auto r = [&](int16_t q) {
        return dpf::reconstruct(dpf::eval_point(dpf::cmp, k0, q), dpf::eval_point(dpf::cmp, k1, q)) & mask;
    };
    EXPECT_EQ(r(static_cast<int16_t>(x - 1)), 42u);
    EXPECT_EQ(r(x), 0u);
    EXPECT_EQ(r(static_cast<int16_t>(x + 1)), 0u);
}

TEST_F(StressScenariosTest, ModintInputClassicPoint)
{
    using in_t = dpf::modint<12>;
    in_t x{0x0abc};
    auto [k0, k1] = dpf::make_dpf(x, uint32_t{321});
    EXPECT_EQ(static_cast<uint32_t>(recon(*dpf::eval_point(k0, x),
                  *dpf::eval_point(k1, x))), 321u);
    in_t off{0x0abd};
    EXPECT_EQ(static_cast<uint32_t>(recon(*dpf::eval_point(k0, off),
                  *dpf::eval_point(k1, off))), 0u);
}

TEST_F(StressScenariosTest, KeywordInputClassicPoint)
{
    using in_t = dpf::keyword<3, dpf::alphabets::hex>;
    in_t x{"abc"};
    auto [k0, k1] = dpf::make_dpf(x, uint32_t{77});
    EXPECT_EQ(static_cast<uint32_t>(recon(*dpf::eval_point(k0, x),
                  *dpf::eval_point(k1, x))), 77u);
    in_t off{"abd"};
    EXPECT_EQ(static_cast<uint32_t>(recon(*dpf::eval_point(k0, off),
                  *dpf::eval_point(k1, off))), 0u);
}

TEST_F(StressScenariosTest, CmpPackedAtDeepestUnderDoernerShelat)
{
    uint32_t x = 0x00abcdefu;
    uint32_t x0 = 0x12345678u;
    uint32_t x1 = x ^ x0;

    reset_tape_roots();
    auto dealer = dpf::make_dpf(x,
        dpf::root_sampler_t<dpf::prg::aes128>{take_root},
        dpf::at<14>(uint8_t{3}, uint8_t{5}),
        uint32_t{9},
        dpf::lt(uint64_t{42}));
    reset_tape_roots();
    dpf::ds_randomness<simde__m128i (*)(), PadA> rng{take_root, {}};
    auto ds = dpf::make_dpf_doerner_shelat(x0, x1, rng,
        dpf::at<14>(uint8_t{3}, uint8_t{5}),
        uint32_t{9},
        dpf::lt(uint64_t{42}));

    EXPECT_TRUE(same_incr_key(dealer.first, ds.first));
    EXPECT_TRUE(same_incr_key(dealer.second, ds.second));

    const uint64_t mask = dealer.first.cmp().mask;
    for (uint32_t q : {x - 1u, x, x + 1u, 0u})
    {
        EXPECT_EQ(dpf::reconstruct(dpf::eval_point(dpf::cmp, dealer.first, q), dpf::eval_point(dpf::cmp, dealer.second, q)) & mask,
            dpf::reconstruct(dpf::eval_point(dpf::cmp, ds.first, q), dpf::eval_point(dpf::cmp, ds.second, q)) & mask);
    }
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 14>, dealer.first, x),
                  *dpf::eval_point(dpf::out<0, 14>, dealer.second, x)), uint8_t{3});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<2, 32>, ds.first, x),
                  *dpf::eval_point(dpf::out<2, 32>, ds.second, x)), uint32_t{9});
}

TEST_F(StressScenariosTest, Packed16xU8PartialIntervalOffAlignment)
{
    uint16_t x = 0x0c34;
    auto [k0, k1] = dpf::make_dpf(x,
        dpf::at<12>(
            uint8_t{1}, uint8_t{2}, uint8_t{3}, uint8_t{4},
            uint8_t{5}, uint8_t{6}, uint8_t{7}, uint8_t{8},
            uint8_t{9}, uint8_t{10}, uint8_t{11}, uint8_t{12},
            uint8_t{13}, uint8_t{14}, uint8_t{15}, uint8_t{16}),
        uint32_t{7});
    constexpr std::size_t N = 12, I = 0;
    const uint16_t lane = x >> (16 - N);
    // A partial interval whose bounds are not on 16-lane leaf boundaries.
    const uint16_t from = static_cast<uint16_t>((lane & ~uint16_t{0xf}) + 3u);
    const uint16_t to = static_cast<uint16_t>((lane | uint16_t{0xf}) + 5u);
    auto [b0, it0] = dpf::eval_interval(dpf::out<I, N>, k0, from, to);
    auto [b1, it1] = dpf::eval_interval(dpf::out<I, N>, k1, from, to);
    (void)it0; (void)it1;

    // The buffer is filled from the leaf-node floor of `from` (opl==16 lanes),
    // so index relative to that aligned start, not to `from` itself.
    const uint16_t from_floor = static_cast<uint16_t>(lane & ~uint16_t{0xf});
    const std::size_t idx = static_cast<std::size_t>(lane - from_floor);
    ASSERT_LT(idx, b0.size());
    EXPECT_EQ(recon(b0[idx], b1[idx]),
        recon(*dpf::eval_point(dpf::out<I, N>, k0, x),
            *dpf::eval_point(dpf::out<I, N>, k1, x)));
    // Slot 0 was programmed with value 1 at the point x's lane.
    EXPECT_EQ(recon(b0[idx], b1[idx]), uint8_t{1});
}

// ===========================================================================
// D) Non-key: classic multi-output interval & recipe modes (smoke).
// ===========================================================================

TEST_F(StressScenariosTest, ClassicMultiOutputInterval012)
{
    uint8_t x = 0x55;
    auto [k0, k1] = dpf::make_dpf(x, uint32_t{2}, uint32_t{3}, uint32_t{4});
    auto [b0, it0] = dpf::eval_interval<0, 1, 2>(k0, uint8_t{0}, uint8_t{0xff});
    auto [b1, it1] = dpf::eval_interval<0, 1, 2>(k1, uint8_t{0}, uint8_t{0xff});

    auto zip0 = dpf::tuple_as_zip(it0);
    auto zip1 = dpf::tuple_as_zip(it1);
    auto i0 = std::cbegin(zip0);
    auto i1 = std::cbegin(zip1);
    uint32_t cur = 0;
    for (; i0 != std::cend(zip0); ++i0, ++i1, ++cur)
    {
        const bool at = (static_cast<uint8_t>(cur) == x);
        EXPECT_EQ(static_cast<uint32_t>(recon(std::get<0>(*i0), std::get<0>(*i1))), at ? 2u : 0u);
        EXPECT_EQ(static_cast<uint32_t>(recon(std::get<1>(*i0), std::get<1>(*i1))), at ? 3u : 0u);
        EXPECT_EQ(static_cast<uint32_t>(recon(std::get<2>(*i0), std::get<2>(*i1))), at ? 4u : 0u);
    }
    EXPECT_EQ(cur, 256u);
}

// ===========================================================================
// Additional cross-cutting coverage.
// ===========================================================================

TEST_F(StressScenariosTest, MlEvalSweepAroundPointPrefixSlot)
{
    uint16_t x = 0x4d80;
    auto [k0, k1] = dpf::make_dpf(x, dpf::at<8>(dpf::bit::one), uint32_t{0xabcdef01});
    using KT = std::decay_t<decltype(k0)>;
    dpf::nonmemoizing_path_memoizer<KT> p0{}, p1{};

    const uint16_t xtop = static_cast<uint16_t>(x >> 8);
    for (int d = -40; d <= 40; ++d)
    {
        uint16_t q = static_cast<uint16_t>(x + d);
        auto b0 = dpf::eval_point(dpf::out<0, 8>, k0, q, p0);
        auto b1 = dpf::eval_point(dpf::out<0, 8>, k1, q, p1);
        auto u0 = dpf::eval_point(dpf::out<1, 16>, k0, q, p0);
        auto u1 = dpf::eval_point(dpf::out<1, 16>, k1, q, p1);
        EXPECT_EQ(static_cast<bool>(recon(*b0, *b1)),
            static_cast<uint16_t>(q >> 8) == xtop) << "q=" << q;
        uint32_t want = (q == x) ? 0xabcdef01u : 0u;
        EXPECT_EQ(recon(*u0, *u1), want) << "q=" << q;
    }
    // Explicit off-prefix bucket.
    uint16_t other = static_cast<uint16_t>(x ^ 0x8000u);
    EXPECT_FALSE(static_cast<bool>(recon(*dpf::eval_point(dpf::out<0, 8>, k0, other), *dpf::eval_point(dpf::out<0, 8>, k1, other))));
}

TEST_F(StressScenariosTest, MlInnerProductExplicitMemoizerMatchesDefault)
{
    uint16_t x = 0x9c40;
    auto [k0, k1] = make_mixed_ml(x);
    using KT = std::decay_t<decltype(k0)>;
    constexpr std::size_t N = 8, I = 0;
    const uint16_t from = 0, to = 0xff;
    std::vector<uint64_t> w(256);
    for (std::size_t i = 0; i < w.size(); ++i) w[i] = (i * 7u + 1u) & 0x1fu;

    auto a = dpf::eval_inner_product(dpf::out<I, N>, k0, from, to, w);
    auto b = dpf::eval_inner_product(dpf::out<I, N>, k1, from, to, w);
    auto m0 = dpf::make_basic_interval_memoizer<KT, I>(from, to);
    auto m1 = dpf::make_basic_interval_memoizer<KT, I>(from, to);
    auto am = dpf::eval_inner_product(dpf::out<I, N>, k0, from, to, w, m0);
    auto bm = dpf::eval_inner_product(dpf::out<I, N>, k1, from, to, w, m1);
    EXPECT_EQ(am, a);
    EXPECT_EQ(bm, b);
}

TEST_F(StressScenariosTest, MlCmpInnerProductMatchesInterval)
{
    uint16_t alpha = 0x00aa;
    auto [k0, k1] = dpf::make_dpf(alpha, dpf::lt_at<8>(uint64_t{5}, uint64_t{1}));
    const uint64_t mask = k0.cmp().mask;
    const uint8_t from = 0x00, to = 0x1f;
    auto b0 = dpf::eval_interval(dpf::cmp, k0, from, to);
    auto b1 = dpf::eval_interval(dpf::cmp, k1, from, to);

    std::vector<uint64_t> w(b0.size());
    uint64_t expect = 0;
    for (std::size_t i = 0; i < w.size(); ++i)
    {
        w[i] = (i * 3u + 2u) & 0xffu;
        const uint64_t value = recon(b0[i], b1[i]) & mask;
        expect = (expect + value * (w[i] & mask)) & mask;
    }
    auto a = dpf::eval_inner_product(dpf::cmp, k0, from, to, w);
    auto b = dpf::eval_inner_product(dpf::cmp, k1, from, to, w);
    EXPECT_EQ((a + b) & mask, expect);
}

TEST_F(StressScenariosTest, ClassicOutFullMatchesIndexedFull)
{
    uint8_t x = 0x2a;
    auto [k0, k1] = dpf::make_dpf(x, uint32_t{7}, uint32_t{9});
    auto [b0, it0] = dpf::eval_full(dpf::out<1, 8>, k0);
    auto [i0, iit0] = dpf::eval_full<1>(k0);
    (void)it0; (void)iit0;
    ASSERT_EQ(b0.size(), i0.size());
    for (std::size_t i = 0; i < b0.size(); ++i)
        EXPECT_EQ(b0[i], i0[i]) << "i=" << i;
}

TEST_F(StressScenariosTest, PrgAesLowmcMultilevelInterval)
{
    uint16_t x = 0x3c5a;
    auto [k0, k1] = dpf::make_dpf<dpf::prg::aes128, dpf::prg::lowmc128>(x,
        dpf::at<8>(uint8_t{42}), uint16_t{7});
    constexpr std::size_t N = 8, I = 0;
    auto [b0, it0] = dpf::eval_interval(dpf::out<I, N>, k0, uint16_t{0}, uint16_t{0xff});
    auto [b1, it1] = dpf::eval_interval(dpf::out<I, N>, k1, uint16_t{0}, uint16_t{0xff});
    (void)it0; (void)it1;
    const std::size_t lane = x >> 8;
    EXPECT_EQ(recon(b0[lane], b1[lane]), uint8_t{42});
    EXPECT_EQ(recon(b0[(lane + 1) & 0xff], b1[(lane + 1) & 0xff]), uint8_t{0});
}

TEST_F(StressScenariosTest, ClassicRecipeMemoizerVariantsAgree)
{
    using dpf_type = dpf::utils::dpf_type_t<dpf::prg::aes128, dpf::prg::aes128,
        uint16_t, uint32_t>;
    uint16_t x = 0x0246;
    auto [k0, k1] = dpf::make_dpf(x, uint32_t{4242});

    std::vector<uint16_t> pts = {0x0000, x, 0x0247, 0x0800, 0x0fff};
    std::sort(pts.begin(), pts.end());
    pts.erase(std::unique(pts.begin(), pts.end()), pts.end());
    auto recipe = dpf::make_sequence_recipe<dpf_type>(pts.begin(), pts.end());

    auto md0 = dpf::make_double_space_sequence_memoizer<dpf_type>(recipe);
    auto md1 = dpf::make_double_space_sequence_memoizer<dpf_type>(recipe);
    auto [d0, dit0] = dpf::eval_sequence(k0, recipe, md0);
    auto [d1, dit1] = dpf::eval_sequence(k1, recipe, md1);

    auto mf0 = dpf::make_full_tree_sequence_memoizer<dpf_type>(recipe);
    auto mf1 = dpf::make_full_tree_sequence_memoizer<dpf_type>(recipe);
    auto [f0, fit0] = dpf::eval_sequence(k0, recipe, mf0);
    auto [f1, fit1] = dpf::eval_sequence(k1, recipe, mf1);

    auto di0 = std::begin(dit0);
    auto di1 = std::begin(dit1);
    auto fi0 = std::begin(fit0);
    auto fi1 = std::begin(fit1);
    std::size_t idx = 0;
    for (; di0 != std::end(dit0); ++di0, ++di1, ++fi0, ++fi1, ++idx)
    {
        auto d = static_cast<uint32_t>(recon(*di0, *di1));
        auto f = static_cast<uint32_t>(recon(*fi0, *fi1));
        EXPECT_EQ(d, f) << "idx=" << idx;
        EXPECT_EQ(d, (pts[idx] == x) ? 4242u : 0u) << "idx=" << idx;
    }
}

TEST_F(StressScenariosTest, ClassicRecipeEntireNodeVsOutputOnly)
{
    using dpf_type = dpf::utils::dpf_type_t<dpf::prg::aes128, dpf::prg::aes128,
        uint16_t, uint32_t>;
    uint16_t x = 0x0123;
    auto [k0, k1] = dpf::make_dpf(x, uint32_t{88});

    std::vector<uint16_t> pts = {0x0000, 0x0100, x, 0x0200, 0x0345, 0x0fff};
    std::sort(pts.begin(), pts.end());
    pts.erase(std::unique(pts.begin(), pts.end()), pts.end());

    auto recipe = dpf::make_sequence_recipe<dpf_type>(pts.begin(), pts.end());

    auto [e0, eit0] = dpf::eval_sequence(k0, recipe, dpf::return_entire_node_tag_{});
    auto [e1, eit1] = dpf::eval_sequence(k1, recipe, dpf::return_entire_node_tag_{});
    auto [o0, oit0] = dpf::eval_sequence(k0, recipe, dpf::return_output_only_tag_{});
    auto [o1, oit1] = dpf::eval_sequence(k1, recipe, dpf::return_output_only_tag_{});

    auto ei0 = std::begin(eit0);
    auto ei1 = std::begin(eit1);
    auto oi0 = std::begin(oit0);
    auto oi1 = std::begin(oit1);
    std::size_t idx = 0;
    for (; oi0 != std::end(oit0); ++ei0, ++ei1, ++oi0, ++oi1, ++idx)
    {
        auto e = static_cast<uint32_t>(recon(*ei0, *ei1));
        auto o = static_cast<uint32_t>(recon(*oi0, *oi1));
        EXPECT_EQ(e, o) << "idx=" << idx;
        uint32_t want = (pts[idx] == x) ? 88u : 0u;
        EXPECT_EQ(o, want) << "idx=" << idx;
    }
}

// ---------------------------------------------------------------------------
// Extra symmetry / scenario coverage (wave 2)
// ---------------------------------------------------------------------------

TEST_F(StressScenariosTest, ClassicBreadthFirstMatchesPoint)
{
    using dpf_type = dpf::utils::dpf_type_t<dpf::prg::aes128, dpf::prg::aes128,
        uint16_t, uint32_t>;
    uint16_t x = 0x0abc;
    auto [k0, k1] = dpf::make_dpf(x, uint32_t{777});
    std::vector<uint16_t> pts = {0, 1, x, static_cast<uint16_t>(x ^ 1), 0xffff};
    std::sort(pts.begin(), pts.end());
    pts.erase(std::unique(pts.begin(), pts.end()), pts.end());

    // `eval_sequence_breadth_first` returns a pair{buffer, iterable}. The
    // buffer is laid out per-leaf (outputs_per_leaf slots per query), so the
    // per-point outputs must be read through the iterable, not by indexing the
    // buffer directly.
    auto [b0, iter0] = dpf::eval_sequence_breadth_first(k0, pts.begin(), pts.end());
    auto [b1, iter1] = dpf::eval_sequence_breadth_first(k1, pts.begin(), pts.end());
    (void)b0;
    (void)b1;
    auto i0 = std::begin(iter0);
    auto i1 = std::begin(iter1);
    for (std::size_t i = 0; i0 != std::end(iter0); ++i0, ++i1, ++i)
    {
        EXPECT_EQ(recon(*i0, *i1),
            recon(*dpf::eval_point(k0, pts[i]), *dpf::eval_point(k1, pts[i])))
            << "i=" << i;
    }
}

TEST_F(StressScenariosTest, ClassicFullInnerProductMatchesFullInterval)
{
    using dpf_type = dpf::utils::dpf_type_t<dpf::prg::aes128, dpf::prg::aes128,
        uint8_t, uint32_t>;
    uint8_t x = 0x42;
    auto [k0, k1] = dpf::make_dpf(x, uint32_t{9});
    auto [buf0, it0] = dpf::eval_full(k0);
    auto [buf1, it1] = dpf::eval_full(k1);
    (void)it0;
    (void)it1;
    std::vector<uint64_t> w(buf0.size());
    uint64_t expect = 0;
    for (std::size_t i = 0; i < w.size(); ++i)
    {
        w[i] = (i % 17u) + 1u;
        expect += static_cast<uint64_t>(recon(buf0[i], buf1[i])) * w[i];
    }
    auto memo0 = dpf::make_basic_full_memoizer(k0);
    auto memo1 = dpf::make_basic_full_memoizer(k1);
    dpf::eval_prepare_full(k0, memo0);
    dpf::eval_prepare_full(k1, memo1);
    auto ip0 = dpf::eval_full_inner_product(k0, w, memo0);
    auto ip1 = dpf::eval_full_inner_product(k1, w, memo1);
    // Leaf shares are subtractive: reconstruct(y0, y1) = y0 - y1.
    EXPECT_EQ(static_cast<uint64_t>(recon(ip0, ip1)), expect);
}

TEST_F(StressScenariosTest, MlXorSlotInnerProduct)
{
    // XOR-packed prefix slot: IP uses xor-and accumulation.
    uint32_t x = 0x00a5b6c7u;
    auto [k0, k1] = dpf::make_dpf(x,
        dpf::at<12>(dpf::xor_wrapper<uint8_t>{0xab}),
        uint32_t{1});
    const uint32_t lane = x >> (32 - 12);
    const uint32_t from = lane & ~0xfu;
    const uint32_t to = from + 15u;
    auto [buf0, it0] = dpf::eval_interval(dpf::out<0, 12>, k0, from, to);
    auto [buf1, it1] = dpf::eval_interval(dpf::out<0, 12>, k1, from, to);
    (void)it0;
    (void)it1;
    std::vector<uint64_t> w(buf0.size(), 0);
    uint8_t expect = 0;
    for (std::size_t i = 0; i < w.size(); ++i)
    {
        w[i] = (i & 1u) ? 0xffu : 0u;
        auto v = static_cast<uint8_t>(recon(buf0[i], buf1[i]));
        expect = static_cast<uint8_t>(expect ^ (v & static_cast<uint8_t>(w[i])));
    }
    auto ip0 = dpf::eval_inner_product(dpf::out<0, 12>, k0, from, to, w);
    auto ip1 = dpf::eval_inner_product(dpf::out<0, 12>, k1, from, to, w);
    EXPECT_EQ(static_cast<uint8_t>(ip0 ^ ip1), expect);
}

TEST_F(StressScenariosTest, MlBitstringDeepestOutput)
{
    uint32_t x = 0x11223344u;
    using bs = dpf::bitstring<20, uint8_t>;
    auto [k0, k1] = dpf::make_dpf(x, dpf::at<10>(dpf::bit::one), bs{});
    // Just ensure gen+point eval compile and off-point is zero-ish for the bit.
    EXPECT_TRUE(static_cast<bool>(
        recon(*dpf::eval_point(dpf::out<0, 10>, k0, x), *dpf::eval_point(dpf::out<0, 10>, k1, x))));
    EXPECT_FALSE(static_cast<bool>(
        recon(*dpf::eval_point(dpf::out<0, 10>, k0, x ^ 0x80000000u), *dpf::eval_point(dpf::out<0, 10>, k1, x ^ 0x80000000u))));
}

TEST_F(StressScenariosTest, MlGeqFullCmpMatchesPointSweep)
{
    const uint8_t alpha = 0x40;
    auto [k0, k1] = dpf::make_dpf(alpha, dpf::geq(uint16_t{5}, uint16_t{1}));
    auto b0 = dpf::eval_full(dpf::cmp, k0);
    auto b1 = dpf::eval_full(dpf::cmp, k1);
    const uint64_t mask = k0.cmp().mask;
    ASSERT_EQ(b0.size(), 256u);
    for (uint16_t q = 0; q < 256; ++q)
    {
        auto got = recon(b0[q], b1[q]) & mask;
        auto want = (static_cast<uint8_t>(q) >= alpha) ? 5u : 1u;
        EXPECT_EQ(got, want) << "q=" << q;
    }
}

TEST_F(StressScenariosTest, ClassicMultiLeafPathMemoizerReuse)
{
    using dpf_type = dpf::utils::dpf_type_t<dpf::prg::aes128, dpf::prg::aes128,
        uint16_t, uint32_t, dpf::xor_wrapper<uint32_t>>;
    uint16_t x = 0x55aa;
    auto [k0, k1] = dpf::make_dpf(x, uint32_t{11},
        dpf::xor_wrapper<uint32_t>{0x2222});
    dpf::basic_path_memoizer<dpf_type> p0{}, p1{};
    for (uint16_t q : {x, static_cast<uint16_t>(x ^ 1), uint16_t{0}, uint16_t{0xffff}})
    {
        auto a0 = dpf::eval_point<0>(k0, q, p0);
        auto a1 = dpf::eval_point<0>(k1, q, p1);
        auto b0 = dpf::eval_point<1>(k0, q, p0);
        auto b1 = dpf::eval_point<1>(k1, q, p1);
        EXPECT_EQ(recon(*a0, *a1),
            recon(*dpf::eval_point<0>(k0, q), *dpf::eval_point<0>(k1, q)));
        EXPECT_EQ(recon(*b0, *b1),
            recon(*dpf::eval_point<1>(k0, q), *dpf::eval_point<1>(k1, q)));
    }
}

TEST_F(StressScenariosTest, DummyInteriorLowmcExteriorMultilevel)
{
    uint32_t x = 0x0f1e2d3cu;
    auto [k0, k1] = dpf::make_dpf<dpf::prg::dummy, dpf::prg::lowmc128>(x,
        dpf::at<12>(uint8_t{9}), uint16_t{4});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 12>, k0, x),
                  *dpf::eval_point(dpf::out<0, 12>, k1, x)),
        uint8_t{9});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<1>, k0, x),
                  *dpf::eval_point(dpf::out<1>, k1, x)),
        uint16_t{4});
}

TEST_F(StressScenariosTest, ClassicMixedFullTreeFullMemoizer)
{
    using dpf_type = dpf::utils::dpf_type_t<dpf::prg::aes128, dpf::prg::aes128,
        uint8_t, uint16_t, dpf::xor_wrapper<uint16_t>>;
    uint8_t x = 0x11;
    auto [k0, k1] = dpf::make_dpf(x, uint16_t{3},
        dpf::xor_wrapper<uint16_t>{0x00ff});
    auto memo0 = dpf::make_full_tree_full_memoizer<dpf_type>();
    auto memo1 = dpf::make_full_tree_full_memoizer<dpf_type>();
    auto [bufs0, its0] = dpf::eval_full<0, 1>(k0, memo0);
    auto [bufs1, its1] = dpf::eval_full<0, 1>(k1, memo1);
    (void)its0;
    (void)its1;
    auto & a0 = std::get<0>(bufs0);
    auto & a1 = std::get<0>(bufs1);
    auto & b0 = std::get<1>(bufs0);
    auto & b1 = std::get<1>(bufs1);
    // Spot-check a few domain points via buffer indexing through point eval.
    for (uint8_t q : {uint8_t{0}, x, static_cast<uint8_t>(x ^ 1), uint8_t{0xff}})
    {
        EXPECT_EQ(recon(*dpf::eval_point<0>(k0, q), *dpf::eval_point<0>(k1, q)),
            recon(*dpf::eval_point<0>(k0, q), *dpf::eval_point<0>(k1, q)));
        EXPECT_EQ(recon(*dpf::eval_point<1>(k0, q), *dpf::eval_point<1>(k1, q)),
            (q == x) ? dpf::xor_wrapper<uint16_t>{0x00ff}
                     : dpf::xor_wrapper<uint16_t>{0});
    }
    (void)a0;
    (void)a1;
    (void)b0;
    (void)b1;
}

TEST_F(StressScenariosTest, MlEqAtWithPackedNeighbors)
{
    uint32_t x = 0x00c0ffeeu;
    auto [k0, k1] = dpf::make_dpf(x,
        dpf::at<12>(uint8_t{1}, uint8_t{2}),
        dpf::eq_at<16>(uint16_t{99}, uint16_t{7}));
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 12>, k0, x),
                  *dpf::eval_point(dpf::out<0, 12>, k1, x)),
        uint8_t{1});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<1, 12>, k0, x),
                  *dpf::eval_point(dpf::out<1, 12>, k1, x)),
        uint8_t{2});
    // eq_at becomes a placed point output with addend absorb.
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<2, 16>, k0, x),
                  *dpf::eval_point(dpf::out<2, 16>, k1, x)),
        uint16_t{99});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<2, 16>, k0, x ^ 0x00010000u),
                  *dpf::eval_point(dpf::out<2, 16>, k1, x ^ 0x00010000u)),
        uint16_t{7});
}

// ===========================================================================
// E) Bug-1 regression: multilevel gen + point eval for non-native input types
//    (`modint`, `keyword`). These exercise `lane_input` / threshold casts.
// ===========================================================================

TEST_F(StressScenariosTest, ModintMultilevelGenAndPoint)
{
    using in_t = dpf::modint<10>;
    in_t x{3};
    auto [k0, k1] = dpf::make_dpf(x, dpf::at<6>(uint8_t{1}), uint16_t{2});

    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 6>, k0, x),
                  *dpf::eval_point(dpf::out<0, 6>, k1, x)),
        uint8_t{1});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<1>, k0, x),
                  *dpf::eval_point(dpf::out<1>, k1, x)),
        uint16_t{2});

    // Off-point on the deepest slot reconstructs to zero.
    in_t off{7};
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<1>, k0, off),
                  *dpf::eval_point(dpf::out<1>, k1, off)),
        uint16_t{0});
}

TEST_F(StressScenariosTest, ModintMultilevelWithCmp)
{
    using in_t = dpf::modint<12>;
    in_t x{0x2ab};
    auto [k0, k1] = dpf::make_dpf(x, dpf::at<6>(uint8_t{5}), uint16_t{9},
        dpf::lt(uint16_t{4}, uint16_t{1}));
    ASSERT_TRUE(k0.has_cmp());
    const uint64_t mask = k0.cmp().mask;
    // Full-domain cmp on the 12-bit input: true-value 4 below threshold, 1 at/above.
    for (unsigned q = 0; q < 0x1000u; q += 0x11u)
    {
        in_t qi{q};
        const auto got = dpf::reconstruct(dpf::eval_point(dpf::cmp, k0, qi), dpf::eval_point(dpf::cmp, k1, qi)) & mask;
        const auto want = (q < 0x2abu) ? uint64_t{4} : uint64_t{1};
        EXPECT_EQ(got, want) << "q=" << q;
    }
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 6>, k0, x),
                  *dpf::eval_point(dpf::out<0, 6>, k1, x)),
        uint8_t{5});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<1>, k0, x),
                  *dpf::eval_point(dpf::out<1>, k1, x)),
        uint16_t{9});
}

TEST_F(StressScenariosTest, KeywordMultilevelGenAndPoint)
{
    using in_t = dpf::keyword<3, dpf::alphabets::hex>;
    in_t x{"abc"};
    auto [k0, k1] = dpf::make_dpf(x, dpf::at<6>(uint8_t{1}), uint16_t{2});

    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 6>, k0, x),
                  *dpf::eval_point(dpf::out<0, 6>, k1, x)),
        uint8_t{1});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<1>, k0, x),
                  *dpf::eval_point(dpf::out<1>, k1, x)),
        uint16_t{2});

    in_t off{"abd"};
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<1>, k0, off),
                  *dpf::eval_point(dpf::out<1>, k1, off)),
        uint16_t{0});
}

// ===========================================================================
// F) Dealer <-> Doerner-Shelat *byte-for-byte* identity across rich scenarios.
//    All use matched entropy: same `take_root` roots and same PadA tape order
//    as the dealer's `root_sampler`. `same_incr_key` now also asserts the cmp
//    channel (cmp_meta / value_cw / cw_last / cmp_addend) and public addends.
// ===========================================================================

TEST_F(StressScenariosTest, DsIdentityManyLevelsMixedWidthsXorAdditiveCmpLt)
{
    uint32_t x = 0x00abcdefu;
    uint32_t x0 = 0x12345678u;
    uint32_t x1 = x ^ x0;

    reset_tape_roots();
    auto dealer = dpf::make_dpf(x,
        dpf::root_sampler_t<dpf::prg::aes128>{take_root},
        dpf::at<8>(dpf::bit::one),
        dpf::at<16>(uint8_t{3}, dpf::xor_wrapper<uint8_t>{0xa5}),
        dpf::at<24>(uint16_t{7}),
        uint32_t{9},
        dpf::lt(uint64_t{42}));
    reset_tape_roots();
    dpf::ds_randomness<simde__m128i (*)(), PadA> rng{take_root, {}};
    auto ds = dpf::make_dpf_doerner_shelat(x0, x1, rng,
        dpf::at<8>(dpf::bit::one),
        dpf::at<16>(uint8_t{3}, dpf::xor_wrapper<uint8_t>{0xa5}),
        dpf::at<24>(uint16_t{7}),
        uint32_t{9},
        dpf::lt(uint64_t{42}));

    EXPECT_TRUE(same_incr_key(dealer.first, ds.first));
    EXPECT_TRUE(same_incr_key(dealer.second, ds.second));

    // Sanity: reconstruction still correct after the byte-identity assertions.
    // Output indices: 0=bit@8, 1=u8@16, 2=xor_u8@16, 3=u16@24, 4=u32@32.
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<1, 16>, dealer.first, x),
                  *dpf::eval_point(dpf::out<1, 16>, dealer.second, x)), uint8_t{3});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<4, 32>, ds.first, x),
                  *dpf::eval_point(dpf::out<4, 32>, ds.second, x)), uint32_t{9});
    const uint64_t mask = dealer.first.cmp().mask;
    for (uint32_t q : {x - 1u, x, x + 1u, 0u})
    {
        EXPECT_EQ(dpf::reconstruct(dpf::eval_point(dpf::cmp, dealer.first, q), dpf::eval_point(dpf::cmp, dealer.second, q)) & mask,
            dpf::reconstruct(dpf::eval_point(dpf::cmp, ds.first, q), dpf::eval_point(dpf::cmp, ds.second, q)) & mask);
    }
}

TEST_F(StressScenariosTest, DsIdentityPacked16xU8DeepestGeq)
{
    uint32_t x = 0x00abcdefu;
    uint32_t x0 = 0x0f0f0f0fu;
    uint32_t x1 = x ^ x0;

    reset_tape_roots();
    auto dealer = dpf::make_dpf(x,
        dpf::root_sampler_t<dpf::prg::aes128>{take_root},
        dpf::at<12>(
            uint8_t{1}, uint8_t{2}, uint8_t{3}, uint8_t{4},
            uint8_t{5}, uint8_t{6}, uint8_t{7}, uint8_t{8},
            uint8_t{9}, uint8_t{10}, uint8_t{11}, uint8_t{12},
            uint8_t{13}, uint8_t{14}, uint8_t{15}, uint8_t{16}),
        uint32_t{5},
        dpf::geq(uint16_t{100}, uint16_t{1}));
    reset_tape_roots();
    dpf::ds_randomness<simde__m128i (*)(), PadA> rng{take_root, {}};
    auto ds = dpf::make_dpf_doerner_shelat(x0, x1, rng,
        dpf::at<12>(
            uint8_t{1}, uint8_t{2}, uint8_t{3}, uint8_t{4},
            uint8_t{5}, uint8_t{6}, uint8_t{7}, uint8_t{8},
            uint8_t{9}, uint8_t{10}, uint8_t{11}, uint8_t{12},
            uint8_t{13}, uint8_t{14}, uint8_t{15}, uint8_t{16}),
        uint32_t{5},
        dpf::geq(uint16_t{100}, uint16_t{1}));

    EXPECT_TRUE(same_incr_key(dealer.first, ds.first));
    EXPECT_TRUE(same_incr_key(dealer.second, ds.second));

    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 12>, ds.first, x),
                  *dpf::eval_point(dpf::out<0, 12>, ds.second, x)), uint8_t{1});
}

TEST_F(StressScenariosTest, DsIdentityClassicMultiLeafXorAdditiveBytes)
{
    // Classic-shaped pack -> classic key; assert BYTE identity, not just recon.
    uint32_t x = 0x00abcdefu;
    uint32_t x0 = 0x12345678u;
    uint32_t x1 = x ^ x0;

    reset_tape_roots();
    auto dealer = dpf::make_dpf(x,
        dpf::root_sampler_t<dpf::prg::aes128>{take_root},
        uint32_t{7}, dpf::xor_wrapper<uint32_t>{0xdeadbeef});
    reset_tape_roots();
    dpf::ds_randomness<simde__m128i (*)(), PadA> rng{take_root, {}};
    auto ds = dpf::make_dpf_doerner_shelat(x0, x1, rng,
        uint32_t{7}, dpf::xor_wrapper<uint32_t>{0xdeadbeef});

    EXPECT_TRUE(same_classic_key(dealer.first, ds.first));
    EXPECT_TRUE(same_classic_key(dealer.second, ds.second));

    EXPECT_EQ(recon(*dpf::eval_point<0>(dealer.first, x),
                  *dpf::eval_point<0>(dealer.second, x)), uint32_t{7});
}

TEST_F(StressScenariosTest, DsIdentityIntermediateWildcardConcreteSiblings)
{
    uint32_t x = 0x55aa55aau;
    uint32_t x0 = 0x0f0f0f0fu;
    uint32_t x1 = x ^ x0;
    dpf::wildcard_value<uint32_t> wc;

    reset_tape_roots();
    auto dealer = dpf::make_dpf(x,
        dpf::root_sampler_t<dpf::prg::aes128>{take_root},
        dpf::at<10>(dpf::bit::one),
        dpf::at<16>(uint16_t{5}, wc),   // concrete sibling next to the wildcard
        uint32_t{9});
    reset_tape_roots();
    dpf::ds_randomness<simde__m128i (*)(), PadA> rng{take_root, {}};
    auto ds = dpf::make_dpf_doerner_shelat(x0, x1, rng,
        dpf::at<10>(dpf::bit::one),
        dpf::at<16>(uint16_t{5}, wc),
        uint32_t{9});

    // Non-wildcard leaves + CWs + wildcard blinds are all byte-identical.
    EXPECT_TRUE(same_incr_key(dealer.first, ds.first));
    EXPECT_TRUE(same_incr_key(dealer.second, ds.second));

    // Concrete parts still reconstruct.
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<1, 16>, dealer.first, x),
                  *dpf::eval_point(dpf::out<1, 16>, dealer.second, x)), uint16_t{5});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<3, 32>, dealer.first, x),
                  *dpf::eval_point(dpf::out<3, 32>, dealer.second, x)), uint32_t{9});
}

TEST_F(StressScenariosTest, DsIdentityFixedpointAtWithCmp)
{
    using fp16 = grotto::fixedpoint<16>;
    uint32_t x = 0x0abcdef0u;
    uint32_t x0 = 0x11111111u;
    uint32_t x1 = x ^ x0;
    fp16 y = fp16::from_raw(0x00018000);

    reset_tape_roots();
    auto dealer = dpf::make_dpf(x,
        dpf::root_sampler_t<dpf::prg::aes128>{take_root},
        dpf::at<12>(y),
        fp16::from_raw(0x00030000),
        dpf::lt(uint64_t{1000}));
    reset_tape_roots();
    dpf::ds_randomness<simde__m128i (*)(), PadA> rng{take_root, {}};
    auto ds = dpf::make_dpf_doerner_shelat(x0, x1, rng,
        dpf::at<12>(y),
        fp16::from_raw(0x00030000),
        dpf::lt(uint64_t{1000}));

    EXPECT_TRUE(same_incr_key(dealer.first, ds.first));
    EXPECT_TRUE(same_incr_key(dealer.second, ds.second));

    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 12>, dealer.first, x),
                  *dpf::eval_point(dpf::out<0, 12>, dealer.second, x)), y);
}

TEST_F(StressScenariosTest, DsIdentityLocalCwProtocolVsDealer)
{
    uint32_t x = 0xabcdef01u;
    uint32_t x0 = 0x11111111u;
    uint32_t x1 = x ^ x0;

    reset_tape_roots();
    auto dealer = dpf::make_dpf(x,
        dpf::root_sampler_t<dpf::prg::aes128>{take_root},
        dpf::at<10>(dpf::bit::one), uint32_t{5});
    reset_tape_roots();
    PadA pads{};
    dpf::local_cw_protocol<PadA> proto{pads};
    auto ds = dpf::make_dpf_doerner_shelat(x0, x1, take_root, proto,
        dpf::at<10>(dpf::bit::one), uint32_t{5});

    EXPECT_TRUE(same_incr_key(dealer.first, ds.first));
    EXPECT_TRUE(same_incr_key(dealer.second, ds.second));

    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<1, 32>, dealer.first, x),
                  *dpf::eval_point(dpf::out<1, 32>, dealer.second, x)), uint32_t{5});
}

TEST_F(StressScenariosTest, DsIdentityAesInteriorLowmcExteriorMultilevel)
{
    uint32_t x = 0x0f1e2d3cu;
    uint32_t x0 = 0x13572468u;
    uint32_t x1 = x ^ x0;

    reset_tape_roots();
    auto dealer = dpf::make_dpf<dpf::prg::aes128, dpf::prg::lowmc128>(x,
        dpf::root_sampler_t<dpf::prg::aes128>{take_root},
        dpf::at<12>(uint8_t{9}), uint16_t{4});
    reset_tape_roots();
    dpf::ds_randomness<simde__m128i (*)(), PadA> rng{take_root, {}};
    auto ds = dpf::make_dpf_doerner_shelat<dpf::prg::aes128, dpf::prg::lowmc128>(
        x0, x1, rng, dpf::at<12>(uint8_t{9}), uint16_t{4});

    EXPECT_TRUE(same_incr_key(dealer.first, ds.first));
    EXPECT_TRUE(same_incr_key(dealer.second, ds.second));

    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 12>, ds.first, x),
                  *dpf::eval_point(dpf::out<0, 12>, ds.second, x)), uint8_t{9});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<1>, ds.first, x),
                  *dpf::eval_point(dpf::out<1>, ds.second, x)), uint16_t{4});
}

TEST_F(StressScenariosTest, DsIdentityWildcardCmpThenAssign)
{
    uint32_t x = 0x00abcdefu;
    uint32_t x0 = 0x12345678u;
    uint32_t x1 = x ^ x0;
    const uint64_t yt = 99u, yf = 3u;

    reset_tape_roots();
    auto dealer = dpf::make_dpf(x,
        dpf::root_sampler_t<dpf::prg::aes128>{take_root},
        dpf::at<12>(uint8_t{5}),
        uint32_t{7},
        dpf::geq(dpf::wildcard_value<uint64_t>{}));
    reset_tape_roots();
    dpf::ds_randomness<simde__m128i (*)(), PadA> rng{take_root, {}};
    auto ds = dpf::make_dpf_doerner_shelat(x0, x1, rng,
        dpf::at<12>(uint8_t{5}),
        uint32_t{7},
        dpf::geq(dpf::wildcard_value<uint64_t>{}));

    EXPECT_TRUE(same_incr_key(dealer.first, ds.first));
    EXPECT_TRUE(same_incr_key(dealer.second, ds.second));
    EXPECT_FALSE(ds.first.cmp_assigned());

    dpf::assign_cmp(ds.first, ds.second, yt, yf);
    dpf::assign_cmp(dealer.first, dealer.second, yt, yf);
    // Public CWs match after independent assign (same δ + identical coeffs).
    using WT = std::decay_t<decltype(ds.first)>;
    EXPECT_TRUE(same_bytes(ds.first.value_cw().data(),
        dealer.first.value_cw().data(),
        ds.first.value_cw().size() * sizeof(typename WT::value_cw_word)));
    EXPECT_EQ(ds.first.cw_last(), dealer.first.cw_last());

    const uint64_t mask = ds.first.cmp().mask;
    for (uint32_t q : {x - 1u, x, x + 1u})
    {
        EXPECT_EQ(dpf::reconstruct(dpf::eval_point(dpf::cmp, ds.first, q), dpf::eval_point(dpf::cmp, ds.second, q)) & mask,
            dpf::reconstruct(dpf::eval_point(dpf::cmp, dealer.first, q), dpf::eval_point(dpf::cmp, dealer.second, q)) & mask)
            << "q=" << q;
    }
    EXPECT_EQ(dpf::reconstruct(ds.first.cmp_addend(), ds.second.cmp_addend()) & mask, yt);
}

TEST_F(StressScenariosTest, DsIdentityLocalCwComplexManyLevelsCmp)
{
    // Real DS path with injectable local_cw_protocol on a rich pack: mixed
    // widths, xor+additive co-located, deepest concrete, and lt cmp.
    uint32_t x = 0x00abcdefu;
    uint32_t x0 = 0x12345678u;
    uint32_t x1 = x ^ x0;

    reset_tape_roots();
    auto dealer = dpf::make_dpf(x,
        dpf::root_sampler_t<dpf::prg::aes128>{take_root},
        dpf::at<8>(dpf::bit::one),
        dpf::at<16>(uint8_t{3}, dpf::xor_wrapper<uint8_t>{0xa5}),
        dpf::at<24>(uint16_t{7}),
        uint32_t{9},
        dpf::lt(uint64_t{42}));
    reset_tape_roots();
    PadA pads{};
    dpf::local_cw_protocol<PadA> proto{pads};
    auto ds = dpf::make_dpf_doerner_shelat(x0, x1, take_root, proto,
        dpf::at<8>(dpf::bit::one),
        dpf::at<16>(uint8_t{3}, dpf::xor_wrapper<uint8_t>{0xa5}),
        dpf::at<24>(uint16_t{7}),
        uint32_t{9},
        dpf::lt(uint64_t{42}));

    EXPECT_TRUE(same_incr_key(dealer.first, ds.first));
    EXPECT_TRUE(same_incr_key(dealer.second, ds.second));
}

TEST_F(StressScenariosTest, DsIdentityModintMultilevelXorAdditiveCmp)
{
    using in_t = dpf::modint<12>;
    constexpr auto to_int = dpf::utils::to_integral_type<in_t>{};
    constexpr auto from_int = dpf::utils::make_from_integral_value<in_t>{};
    in_t x{0x2ab};
    in_t x0{0x111};
    in_t x1 = from_int(static_cast<typename decltype(from_int)::integral_type>(
        to_int(x) ^ to_int(x0)));

    reset_tape_roots();
    auto dealer = dpf::make_dpf(x,
        dpf::root_sampler_t<dpf::prg::aes128>{take_root},
        dpf::at<6>(uint8_t{5}, dpf::xor_wrapper<uint8_t>{0x3c}),
        uint16_t{9},
        dpf::lt(uint16_t{4}, uint16_t{1}));
    reset_tape_roots();
    dpf::ds_randomness<simde__m128i (*)(), PadA> rng{take_root, {}};
    auto ds = dpf::make_dpf_doerner_shelat(x0, x1, rng,
        dpf::at<6>(uint8_t{5}, dpf::xor_wrapper<uint8_t>{0x3c}),
        uint16_t{9},
        dpf::lt(uint16_t{4}, uint16_t{1}));

    EXPECT_TRUE(same_incr_key(dealer.first, ds.first));
    EXPECT_TRUE(same_incr_key(dealer.second, ds.second));

    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 6>, ds.first, x),
                  *dpf::eval_point(dpf::out<0, 6>, ds.second, x)), uint8_t{5});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<2>, ds.first, x),
                  *dpf::eval_point(dpf::out<2>, ds.second, x)), uint16_t{9});
}

TEST_F(StressScenariosTest, DsIdentityKeywordMultilevel)
{
    using in_t = dpf::keyword<3, dpf::alphabets::hex>;
    constexpr auto to_int = dpf::utils::to_integral_type<in_t>{};
    constexpr auto from_int = dpf::utils::make_from_integral_value<in_t>{};
    in_t x{"abc"};
    in_t x0{"a00"};
    in_t x1 = from_int(static_cast<typename decltype(from_int)::integral_type>(
        to_int(x) ^ to_int(x0)));

    reset_tape_roots();
    auto dealer = dpf::make_dpf(x,
        dpf::root_sampler_t<dpf::prg::aes128>{take_root},
        dpf::at<6>(uint8_t{1}), uint16_t{2});
    reset_tape_roots();
    dpf::ds_randomness<simde__m128i (*)(), PadA> rng{take_root, {}};
    auto ds = dpf::make_dpf_doerner_shelat(x0, x1, rng,
        dpf::at<6>(uint8_t{1}), uint16_t{2});

    EXPECT_TRUE(same_incr_key(dealer.first, ds.first));
    EXPECT_TRUE(same_incr_key(dealer.second, ds.second));

    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 6>, ds.first, x),
                  *dpf::eval_point(dpf::out<0, 6>, ds.second, x)), uint8_t{1});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<1>, ds.first, x),
                  *dpf::eval_point(dpf::out<1>, ds.second, x)), uint16_t{2});
}

// ===========================================================================
// G) eval_full coverage: multilevel prefix + deepest (multi-lane), cmp lt/geq
//    sweeps, classic full-tree memoizer multi-leaf, explicit memoizer.
// ===========================================================================

TEST_F(StressScenariosTest, MlEvalFullPrefixAndDeepestMultiLane)
{
    uint16_t x = 0xa5c3;
    auto [k0, k1] = dpf::make_dpf(x, dpf::at<8>(uint8_t{42}),
        dpf::at<12>(uint16_t{7}));

    // Prefix slot out<0,8>: compare several lanes to point eval.
    auto [pb0, pit0] = dpf::eval_full(dpf::out<0, 8>, k0);
    auto [pb1, pit1] = dpf::eval_full(dpf::out<0, 8>, k1);
    (void)pit0; (void)pit1;
    for (int L : {0, 1, x >> 8, (x >> 8) ^ 1, 0xff})
    {
        const uint16_t q = static_cast<uint16_t>(L << 8);
        EXPECT_EQ(recon(pb0[L], pb1[L]),
            recon(*dpf::eval_point(dpf::out<0, 8>, k0, q),
                *dpf::eval_point(dpf::out<0, 8>, k1, q))) << "L=" << L;
    }
    EXPECT_EQ(recon(pb0[x >> 8], pb1[x >> 8]), uint8_t{42});

    // Deepest slot out<1,12>: compare several lanes to point eval.
    auto [db0, dit0] = dpf::eval_full(dpf::out<1, 12>, k0);
    auto [db1, dit1] = dpf::eval_full(dpf::out<1, 12>, k1);
    (void)dit0; (void)dit1;
    for (int L : {0, x >> 4, (x >> 4) ^ 1, 0xfff})
    {
        const uint16_t q = static_cast<uint16_t>(L << 4);
        EXPECT_EQ(recon(db0[L], db1[L]),
            recon(*dpf::eval_point(dpf::out<1, 12>, k0, q),
                *dpf::eval_point(dpf::out<1, 12>, k1, q))) << "L=" << L;
    }
    EXPECT_EQ(recon(db0[x >> 4], db1[x >> 4]), uint16_t{7});
}

// Multilevel eval_full with an explicit per-slot interval memoizer
// (`make_basic_interval_memoizer<Key, I>` stops at meta[I].tree_level).
TEST_F(StressScenariosTest, MlEvalFullWithPerSlotMemoizer)
{
    uint16_t x = 0x0abc;
    auto [k0, k1] = dpf::make_dpf(x, dpf::at<8>(uint8_t{42}), dpf::at<12>(uint16_t{7}));
    using KT = std::decay_t<decltype(k0)>;

    constexpr uint16_t lo = 0;
    constexpr uint16_t hi = 0xff;  // full 8-bit prefix domain
    auto memo0 = dpf::make_basic_interval_memoizer<KT, 0>(lo, hi);
    auto memo1 = dpf::make_basic_interval_memoizer<KT, 0>(lo, hi);
    auto buf0 = dpf::make_output_buffer(dpf::out<0, 8>, k0, lo, hi);
    auto buf1 = dpf::make_output_buffer(dpf::out<0, 8>, k1, lo, hi);
    auto it0 = dpf::eval_full(dpf::out<0, 8>, k0, buf0, memo0);
    auto it1 = dpf::eval_full(dpf::out<0, 8>, k1, buf1, memo1);
    (void)it0;
    (void)it1;

    const uint16_t lane = static_cast<uint16_t>(x >> 8);
    EXPECT_EQ(recon(buf0[lane], buf1[lane]), uint8_t{42});
    EXPECT_EQ(recon(buf0[lane ^ 1u], buf1[lane ^ 1u]), uint8_t{0});
    EXPECT_EQ(recon(buf0[0], buf1[0]),
        recon(*dpf::eval_point(dpf::out<0, 8>, k0, uint16_t{0}),
            *dpf::eval_point(dpf::out<0, 8>, k1, uint16_t{0})));

    // Deepest slot with its own per-slot memoizer (stop = tree_level of I=1).
    constexpr uint16_t dlo = 0;
    constexpr uint16_t dhi = 0xfff;
    auto dmemo0 = dpf::make_basic_interval_memoizer<KT, 1>(dlo, dhi);
    auto dmemo1 = dpf::make_basic_interval_memoizer<KT, 1>(dlo, dhi);
    auto dbuf0 = dpf::make_output_buffer(dpf::out<1, 12>, k0, dlo, dhi);
    auto dbuf1 = dpf::make_output_buffer(dpf::out<1, 12>, k1, dlo, dhi);
    dpf::eval_full(dpf::out<1, 12>, k0, dbuf0, dmemo0);
    dpf::eval_full(dpf::out<1, 12>, k1, dbuf1, dmemo1);
    const uint16_t dlane = static_cast<uint16_t>(x >> 4);
    EXPECT_EQ(recon(dbuf0[dlane], dbuf1[dlane]), uint16_t{7});
    EXPECT_EQ(recon(dbuf0[dlane ^ 1u], dbuf1[dlane ^ 1u]), uint16_t{0});
}

TEST_F(StressScenariosTest, ModintMlEvalFullMatchesPoint)
{
    using in_t = dpf::modint<10>;
    in_t x{0x155};
    auto [k0, k1] = dpf::make_dpf(x, dpf::at<6>(uint8_t{11}), uint16_t{22});
    auto [b0, it0] = dpf::eval_full(dpf::out<0, 6>, k0);
    auto [b1, it1] = dpf::eval_full(dpf::out<0, 6>, k1);
    (void)it0; (void)it1;
    constexpr auto to_int = dpf::utils::to_integral_type<in_t>{};
    const std::size_t lane = static_cast<std::size_t>(to_int(x) >> (10 - 6));
    EXPECT_EQ(recon(b0[lane], b1[lane]), uint8_t{11});
    for (int L : {0, 1, static_cast<int>(lane), static_cast<int>(lane ^ 1u), 0x3f})
    {
        in_t q = dpf::utils::make_from_integral_value<in_t>{}(
            static_cast<typename dpf::utils::make_from_integral_value<in_t>::integral_type>(
                L << (10 - 6)));
        EXPECT_EQ(recon(b0[L], b1[L]),
            recon(*dpf::eval_point(dpf::out<0, 6>, k0, q),
                *dpf::eval_point(dpf::out<0, 6>, k1, q))) << "L=" << L;
    }
}

TEST_F(StressScenariosTest, MlLtFullCmpMatchesPointSweep)
{
    const uint8_t alpha = 0x40;
    auto [k0, k1] = dpf::make_dpf(alpha, dpf::lt(uint16_t{5}, uint16_t{1}));
    auto b0 = dpf::eval_full(dpf::cmp, k0);
    auto b1 = dpf::eval_full(dpf::cmp, k1);
    const uint64_t mask = k0.cmp().mask;
    ASSERT_EQ(b0.size(), 256u);
    bool saw_true = false, saw_false = false;
    for (uint16_t q = 0; q < 256; ++q)
    {
        const auto got = recon(b0[q], b1[q]) & mask;
        const auto want = dpf::reconstruct(
                              dpf::eval_point(dpf::cmp, k0, static_cast<uint8_t>(q)),
                              dpf::eval_point(dpf::cmp, k1, static_cast<uint8_t>(q))) & mask;
        EXPECT_EQ(got, want) << "q=" << q;
        if (got == 5u) saw_true = true;
        if (got == 1u) saw_false = true;
    }
    // Both branches of the lt comparison are actually exercised.
    EXPECT_TRUE(saw_true);
    EXPECT_TRUE(saw_false);
}

TEST_F(StressScenariosTest, ClassicFullTreeMemoizerMultiLeafIndexed)
{
    using dpf_type = dpf::utils::dpf_type_t<dpf::prg::aes128, dpf::prg::aes128,
        uint8_t, uint16_t, dpf::xor_wrapper<uint16_t>>;
    uint8_t x = 0x11;
    auto [k0, k1] = dpf::make_dpf(x, uint16_t{3},
        dpf::xor_wrapper<uint16_t>{0x00ff});
    auto memo0 = dpf::make_full_tree_full_memoizer<dpf_type>();
    auto memo1 = dpf::make_full_tree_full_memoizer<dpf_type>();
    auto [bufs0, its0] = dpf::eval_full<0, 1>(k0, memo0);
    auto [bufs1, its1] = dpf::eval_full<0, 1>(k1, memo1);
    (void)its0; (void)its1;
    auto & a0 = std::get<0>(bufs0);
    auto & a1 = std::get<0>(bufs1);
    auto & c0 = std::get<1>(bufs0);
    auto & c1 = std::get<1>(bufs1);
    ASSERT_EQ(a0.size(), 256u);
    for (int q = 0; q < 256; ++q)
    {
        // Index the memoized full-tree buffers directly and cross-check.
        EXPECT_EQ(recon(a0[q], a1[q]),
            (q == x) ? uint16_t{3} : uint16_t{0}) << "q=" << q;
        EXPECT_EQ(recon(c0[q], c1[q]),
            (q == x) ? dpf::xor_wrapper<uint16_t>{0x00ff}
                     : dpf::xor_wrapper<uint16_t>{0}) << "q=" << q;
        EXPECT_EQ(recon(a0[q], a1[q]),
            recon(*dpf::eval_point<0>(k0, static_cast<uint8_t>(q)),
                *dpf::eval_point<0>(k1, static_cast<uint8_t>(q)))) << "q=" << q;
    }
}

// ===========================================================================
// H) Packed small wildcards at a non-terminal level + full assignment;
//    LowMC / counter_wrapper PRG adapters.
// ===========================================================================

TEST_F(StressScenariosTest, MlPackedSmallWildcardAtNonTerminalAssignAll)
{
    // Eight packed uint8 wildcards at prefix 12 (non-terminal), deepest concrete.
    uint16_t x = 0x4c1d;
    dpf::wildcard_value<uint8_t> w;
    auto [k0, k1] = dpf::make_dpf(x,
        dpf::at<12>(w, w, w, w, w, w, w, w),
        uint32_t{999});

    using KT = std::decay_t<decltype(k0)>;
    static_assert(KT::meta[0].prefix == 12);
    EXPECT_EQ(KT::meta[0].group_id, KT::meta[7].group_id);
    EXPECT_NE(KT::meta[0].group_id, KT::meta[8].group_id);

    // Unassigned packed wildcards throw; deepest concrete still works.
    EXPECT_ANY_THROW((void)dpf::eval_point(dpf::out<0, 12>, k0, x));
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<8>, k0, x),
                  *dpf::eval_point(dpf::out<8>, k1, x)),
        uint32_t{999});

    // Complete assignment of every packed wildcard slot.
    const std::array<uint8_t, 8> want{
        1, 2, 3, 4, 5, 6, 7, 8};
    const std::array<uint8_t, 8> shr0{
        10, 20, 30, 40, 50, 60, 70, 80};
    assign_wildcard_leaf_local<0>(k0, k1, shr0[0],
        static_cast<uint8_t>(want[0] - shr0[0]));
    assign_wildcard_leaf_local<1>(k0, k1, shr0[1],
        static_cast<uint8_t>(want[1] - shr0[1]));
    assign_wildcard_leaf_local<2>(k0, k1, shr0[2],
        static_cast<uint8_t>(want[2] - shr0[2]));
    assign_wildcard_leaf_local<3>(k0, k1, shr0[3],
        static_cast<uint8_t>(want[3] - shr0[3]));
    assign_wildcard_leaf_local<4>(k0, k1, shr0[4],
        static_cast<uint8_t>(want[4] - shr0[4]));
    assign_wildcard_leaf_local<5>(k0, k1, shr0[5],
        static_cast<uint8_t>(want[5] - shr0[5]));
    assign_wildcard_leaf_local<6>(k0, k1, shr0[6],
        static_cast<uint8_t>(want[6] - shr0[6]));
    assign_wildcard_leaf_local<7>(k0, k1, shr0[7],
        static_cast<uint8_t>(want[7] - shr0[7]));

    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 12>, k0, x),
                  *dpf::eval_point(dpf::out<0, 12>, k1, x)), want[0]);
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<3, 12>, k0, x),
                  *dpf::eval_point(dpf::out<3, 12>, k1, x)), want[3]);
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<7, 12>, k0, x),
                  *dpf::eval_point(dpf::out<7, 12>, k1, x)), want[7]);
    // Neighbour lane in the packed leaf is zero after assignment.
    const uint16_t off = flip_lane_lsb(x, 12, 16);
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 12>, k0, off),
                  *dpf::eval_point(dpf::out<0, 12>, k1, off)), uint8_t{0});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<8>, k0, x),
                  *dpf::eval_point(dpf::out<8>, k1, x)),
        uint32_t{999});
}

TEST_F(StressScenariosTest, MlPackedXorWildcardAtNonTerminalAssignAll)
{
    uint16_t x = 0xabcd;
    dpf::wildcard_value<dpf::xor_wrapper<uint8_t>> w;
    auto [k0, k1] = dpf::make_dpf(x,
        dpf::at<10>(w, w, w, w),
        uint16_t{42});

    const std::array<dpf::xor_wrapper<uint8_t>, 4> want{
        dpf::xor_wrapper<uint8_t>{0x11},
        dpf::xor_wrapper<uint8_t>{0x22},
        dpf::xor_wrapper<uint8_t>{0x33},
        dpf::xor_wrapper<uint8_t>{0x44}};
    const std::array<dpf::xor_wrapper<uint8_t>, 4> shr0{
        dpf::xor_wrapper<uint8_t>{0xaa},
        dpf::xor_wrapper<uint8_t>{0xbb},
        dpf::xor_wrapper<uint8_t>{0xcc},
        dpf::xor_wrapper<uint8_t>{0xdd}};
    assign_wildcard_leaf_local<0>(k0, k1, shr0[0], want[0] ^ shr0[0]);
    assign_wildcard_leaf_local<1>(k0, k1, shr0[1], want[1] ^ shr0[1]);
    assign_wildcard_leaf_local<2>(k0, k1, shr0[2], want[2] ^ shr0[2]);
    assign_wildcard_leaf_local<3>(k0, k1, shr0[3], want[3] ^ shr0[3]);

    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 10>, k0, x),
                  *dpf::eval_point(dpf::out<0, 10>, k1, x)), want[0]);
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<3, 10>, k0, x),
                  *dpf::eval_point(dpf::out<3, 10>, k1, x)), want[3]);
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<4>, k0, x),
                  *dpf::eval_point(dpf::out<4>, k1, x)), uint16_t{42});
}

TEST_F(StressScenariosTest, DsIdentityPackedSmallWildcardAtNonTerminal)
{
    uint32_t x = 0x00abcdefu;
    uint32_t x0 = 0x12345678u;
    uint32_t x1 = x ^ x0;
    dpf::wildcard_value<uint8_t> w;

    reset_tape_roots();
    auto dealer = dpf::make_dpf(x,
        dpf::root_sampler_t<dpf::prg::aes128>{take_root},
        dpf::at<14>(w, w, w, w, uint8_t{9}, w, w, w),
        uint32_t{5});
    reset_tape_roots();
    dpf::ds_randomness<simde__m128i (*)(), PadA> rng{take_root, {}};
    auto ds = dpf::make_dpf_doerner_shelat(x0, x1, rng,
        dpf::at<14>(w, w, w, w, uint8_t{9}, w, w, w),
        uint32_t{5});

    EXPECT_TRUE(same_incr_key(dealer.first, ds.first));
    EXPECT_TRUE(same_incr_key(dealer.second, ds.second));

    // Concrete sibling in the packed group + deepest reconstruct before assign.
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<4, 14>, dealer.first, x),
                  *dpf::eval_point(dpf::out<4, 14>, dealer.second, x)),
        uint8_t{9});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<8>, dealer.first, x),
                  *dpf::eval_point(dpf::out<8>, dealer.second, x)),
        uint32_t{5});

    // Full assignment on the dealer keys; DS keys are byte-identical so the
    // same shares complete them equivalently.
    const std::array<uint8_t, 7> want{1, 2, 3, 4, 6, 7, 8};
    const std::array<uint8_t, 7> s0{11, 22, 33, 44, 55, 66, 77};
    // Slot indices of wildcards: 0,1,2,3,5,6,7 (slot 4 is concrete).
    assign_wildcard_leaf_local<0>(dealer.first, dealer.second, s0[0],
        static_cast<uint8_t>(want[0] - s0[0]));
    assign_wildcard_leaf_local<1>(dealer.first, dealer.second, s0[1],
        static_cast<uint8_t>(want[1] - s0[1]));
    assign_wildcard_leaf_local<2>(dealer.first, dealer.second, s0[2],
        static_cast<uint8_t>(want[2] - s0[2]));
    assign_wildcard_leaf_local<3>(dealer.first, dealer.second, s0[3],
        static_cast<uint8_t>(want[3] - s0[3]));
    assign_wildcard_leaf_local<5>(dealer.first, dealer.second, s0[4],
        static_cast<uint8_t>(want[4] - s0[4]));
    assign_wildcard_leaf_local<6>(dealer.first, dealer.second, s0[5],
        static_cast<uint8_t>(want[5] - s0[5]));
    assign_wildcard_leaf_local<7>(dealer.first, dealer.second, s0[6],
        static_cast<uint8_t>(want[6] - s0[6]));

    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 14>, dealer.first, x),
                  *dpf::eval_point(dpf::out<0, 14>, dealer.second, x)),
        want[0]);
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<5, 14>, dealer.first, x),
                  *dpf::eval_point(dpf::out<5, 14>, dealer.second, x)),
        want[4]);
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<7, 14>, dealer.first, x),
                  *dpf::eval_point(dpf::out<7, 14>, dealer.second, x)),
        want[6]);

    // Assign the DS pair with the same shares; reconstruction must match.
    assign_wildcard_leaf_local<0>(ds.first, ds.second, s0[0],
        static_cast<uint8_t>(want[0] - s0[0]));
    assign_wildcard_leaf_local<1>(ds.first, ds.second, s0[1],
        static_cast<uint8_t>(want[1] - s0[1]));
    assign_wildcard_leaf_local<2>(ds.first, ds.second, s0[2],
        static_cast<uint8_t>(want[2] - s0[2]));
    assign_wildcard_leaf_local<3>(ds.first, ds.second, s0[3],
        static_cast<uint8_t>(want[3] - s0[3]));
    assign_wildcard_leaf_local<5>(ds.first, ds.second, s0[4],
        static_cast<uint8_t>(want[4] - s0[4]));
    assign_wildcard_leaf_local<6>(ds.first, ds.second, s0[5],
        static_cast<uint8_t>(want[5] - s0[5]));
    assign_wildcard_leaf_local<7>(ds.first, ds.second, s0[6],
        static_cast<uint8_t>(want[6] - s0[6]));

    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 14>, ds.first, x),
                  *dpf::eval_point(dpf::out<0, 14>, ds.second, x)),
        want[0]);
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<7, 14>, ds.first, x),
                  *dpf::eval_point(dpf::out<7, 14>, ds.second, x)),
        want[6]);
}

TEST_F(StressScenariosTest, DsIdentityPackedWildcardLowmcExteriorThenAssign)
{
    uint32_t x = 0x0f1e2d3cu;
    uint32_t x0 = 0x13572468u;
    uint32_t x1 = x ^ x0;
    dpf::wildcard_value<uint8_t> w;

    reset_tape_roots();
    auto dealer = dpf::make_dpf<dpf::prg::aes128, dpf::prg::lowmc128>(x,
        dpf::root_sampler_t<dpf::prg::aes128>{take_root},
        dpf::at<12>(w, w, w, w),
        uint16_t{77});
    reset_tape_roots();
    dpf::ds_randomness<simde__m128i (*)(), PadA> rng{take_root, {}};
    auto ds = dpf::make_dpf_doerner_shelat<dpf::prg::aes128, dpf::prg::lowmc128>(
        x0, x1, rng, dpf::at<12>(w, w, w, w), uint16_t{77});

    EXPECT_TRUE(same_incr_key(dealer.first, ds.first));
    EXPECT_TRUE(same_incr_key(dealer.second, ds.second));

    const std::array<uint8_t, 4> want{9, 8, 7, 6};
    const std::array<uint8_t, 4> s0{1, 2, 3, 4};
    assign_wildcard_leaf_local<0>(ds.first, ds.second, s0[0],
        static_cast<uint8_t>(want[0] - s0[0]));
    assign_wildcard_leaf_local<1>(ds.first, ds.second, s0[1],
        static_cast<uint8_t>(want[1] - s0[1]));
    assign_wildcard_leaf_local<2>(ds.first, ds.second, s0[2],
        static_cast<uint8_t>(want[2] - s0[2]));
    assign_wildcard_leaf_local<3>(ds.first, ds.second, s0[3],
        static_cast<uint8_t>(want[3] - s0[3]));

    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 12>, ds.first, x),
                  *dpf::eval_point(dpf::out<0, 12>, ds.second, x)), want[0]);
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<3, 12>, ds.first, x),
                  *dpf::eval_point(dpf::out<3, 12>, ds.second, x)), want[3]);
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<4>, ds.first, x),
                  *dpf::eval_point(dpf::out<4>, ds.second, x)), uint16_t{77});
}

TEST_F(StressScenariosTest, PrgCounterWrapperAesClassicEvalIncrements)
{
    using prg = dpf::prg::counter_wrapper<dpf::prg::aes128>;
    const auto before = prg::count();
    uint8_t x = 0x2a;
    auto [k0, k1] = dpf::make_dpf<prg, prg>(x, uint32_t{0x1111});
    const auto after_gen = prg::count();
    EXPECT_GT(after_gen, before);

    (void)dpf::eval_point(k0, x);
    (void)dpf::eval_full(k0);
    const auto after_eval = prg::count();
    EXPECT_GT(after_eval, after_gen);

    EXPECT_EQ(recon(*dpf::eval_point(k0, x), *dpf::eval_point(k1, x)),
        uint32_t{0x1111});
}

TEST_F(StressScenariosTest, PrgCounterWrapperLowmcMultilevelEvalIncrements)
{
    using interior = dpf::prg::counter_wrapper<dpf::prg::lowmc128>;
    using exterior = dpf::prg::counter_wrapper<dpf::prg::aes128>;
    const auto bi = interior::count();
    const auto be = exterior::count();
    uint16_t x = 0x3c5a;
    auto [k0, k1] = dpf::make_dpf<interior, exterior>(x,
        dpf::at<8>(uint8_t{42}), uint16_t{7});
    EXPECT_GT(interior::count(), bi);
    EXPECT_GT(exterior::count(), be);

    const auto bi2 = interior::count();
    const auto be2 = exterior::count();
    (void)dpf::eval_point(dpf::out<0, 8>, k0, x);
    (void)dpf::eval_full(dpf::out<1, 16>, k0);
    EXPECT_GT(interior::count(), bi2);
    EXPECT_GT(exterior::count(), be2);

    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<0, 8>, k0, x),
                  *dpf::eval_point(dpf::out<0, 8>, k1, x)), uint8_t{42});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<1, 16>, k0, x),
                  *dpf::eval_point(dpf::out<1, 16>, k1, x)), uint16_t{7});
}

TEST_F(StressScenariosTest, PrgLowmcBothSidesPackedInterval)
{
    uint16_t x = 0x91a2;
    auto [k0, k1] = dpf::make_dpf<dpf::prg::lowmc128, dpf::prg::lowmc128>(x,
        dpf::at<12>(uint8_t{1}, uint8_t{2}, uint8_t{3}, uint8_t{4}),
        uint32_t{55});
    constexpr std::size_t N = 12;
    const uint16_t lane = static_cast<uint16_t>(x >> (16 - N));
    const uint16_t from = static_cast<uint16_t>(lane & ~uint16_t{0xf});
    const uint16_t to = static_cast<uint16_t>(from + 0x20u);
    auto [b0, it0] = dpf::eval_interval(dpf::out<0, N>, k0, from, to);
    auto [b1, it1] = dpf::eval_interval(dpf::out<0, N>, k1, from, to);
    (void)it0; (void)it1;
    const std::size_t idx = static_cast<std::size_t>(lane - from);
    ASSERT_LT(idx, b0.size());
    EXPECT_EQ(recon(b0[idx], b1[idx]), uint8_t{1});
    EXPECT_EQ(recon(*dpf::eval_point(dpf::out<4>, k0, x),
                  *dpf::eval_point(dpf::out<4>, k1, x)), uint32_t{55});
}