dash(s6): merkle-root-equality conformance precondition

.github/workflows/build.yml

@@ -59,7 +59,7 @@ jobs:
                     test_threading test_weights \
                     test_header_chain test_mempool test_template_builder \
                     test_doge_chain test_compact_blocks test_dash_x11_kat \
-                    test_dash_header_chain test_dash_block_replay \
+                    test_dash_header_chain test_dash_block_replay test_dash_conformance \
                     test_multiaddress_pplns test_pplns_stress \
                     test_hash_link test_decay_pplns \
                     test_pplns_consensus \
@@ -186,7 +186,7 @@ jobs:
                     test_threading test_weights \
                     test_header_chain test_mempool test_template_builder \
                     test_doge_chain test_compact_blocks test_dash_x11_kat \
-                    test_dash_header_chain test_dash_block_replay \
+                    test_dash_header_chain test_dash_block_replay test_dash_conformance \
                     test_hash_link test_decay_pplns \
                     test_pplns_consensus \
                     test_v36_script_sorting test_v36_cross_impl_refhash \

src/impl/dash/version_negotiation.hpp

@@ -0,0 +1,130 @@
+#pragma once
+
+// Dash share-version transition negotiation (older-than-v35 -> v36).
+//
+// Conforms to frstrtr/p2pool-dash (OLDER oracle) — Option A, not a c2pool
+// reinterpretation. Two distinct tallies, deliberately kept apart (the F10
+// version-gate trap):
+//
+//   * get_desired_version_counts() — a PLAIN tally (one vote per share) over a
+//     chain window. Reference: p2pool-dash data.py get_desired_version_counts
+//     as consumed by Share.check()'s confirmed-state guard and by the
+//     AutoRatchet desired-version selection. It is NOT weighted in place.
+//
+//   * get_desired_version_weights() — the SEPARATE WEIGHTED variant
+//     (weight = target_to_average_attempts(target), i.e. expected hashes) the
+//     v36 activation gate consumes. Reference: p2pool-merged-v36 work.py
+//     v36_active = weight[36] / Sum(weight) >= 0.95.
+//
+// The confirmed-state guard (Share.check): a SUCCESSOR-version share may follow
+// its predecessor only if the new version already holds >= 60% of the PLAIN
+// votes in the [9/10 .. 10/10] tail of the CHAIN_LENGTH window; a switch with
+// fewer than CHAIN_LENGTH ancestors is rejected ("without enough history").
+
+#include "share_chain.hpp"   // dash::ShareChain, dash::DashShare
+
+#include <core/target_utils.hpp>  // chain::target_to_average_attempts, bits_to_target
+#include <core/uint256.hpp>       // uint256, uint288
+
+#include <algorithm>
+#include <cstdint>
+#include <map>
+#include <optional>
+
+namespace dash::version_negotiation
+{
+
+// PLAIN desired-version tally over the `dist` shares ending at `start_hash`
+// (inclusive, walking back via prev_hash). One vote per share. Mirrors the
+// older p2pool-dash get_desired_version_counts as used by the SUCCESSOR
+// tail-guard / AutoRatchet — do NOT add work weighting here (F10 trap).
+inline std::map<uint64_t, uint64_t>
+get_desired_version_counts(ShareChain& chain, const uint256& start_hash, uint64_t dist)
+{
+    std::map<uint64_t, uint64_t> res;
+    if (!chain.contains(start_hash)) return res;
+    const uint64_t n = std::min<uint64_t>(dist,
+        static_cast<uint64_t>(chain.get_height(start_hash)));
+    for (auto&& [h, data] : chain.get_chain(start_hash, n)) {
+        (void)h;
+        data.share.invoke([&](auto* obj) {
+            using S = std::remove_pointer_t<decltype(obj)>;
+            if constexpr (std::is_same_v<S, dash::DashShare>)
+                res[obj->m_desired_version] += 1;
+        });
+    }
+    return res;
+}
+
+// WEIGHTED desired-version tally: each share contributes its expected hash
+// count (target_to_average_attempts of its target), matching ShareIndex::work.
+// This is the variant the v36 activation gate consumes — kept separate from the
+// plain count above.
+inline std::map<uint64_t, uint288>
+get_desired_version_weights(ShareChain& chain, const uint256& start_hash, uint64_t dist)
+{
+    std::map<uint64_t, uint288> res;
+    if (!chain.contains(start_hash)) return res;
+    const uint64_t n = std::min<uint64_t>(dist,
+        static_cast<uint64_t>(chain.get_height(start_hash)));
+    for (auto&& [h, data] : chain.get_chain(start_hash, n)) {
+        (void)h;
+        data.share.invoke([&](auto* obj) {
+            using S = std::remove_pointer_t<decltype(obj)>;
+            if constexpr (std::is_same_v<S, dash::DashShare>) {
+                uint288 w = chain::target_to_average_attempts(
+                    chain::bits_to_target(obj->m_bits));
+                res[obj->m_desired_version] += w;
+            }
+        });
+    }
+    return res;
+}
+
+// 60% confirmed-state guard (p2pool-dash data.py Share.check). A SUCCESSOR
+// share is accepted only when its PLAIN vote count reaches floor(total*60/100).
+// The floor matches the oracle's integer `sum*60//100` exactly (e.g. 4/7 votes
+// clears thr=4, 3/7 does not).
+inline bool
+successor_switch_allowed(const std::map<uint64_t, uint64_t>& plain_counts,
+                         uint64_t successor_version)
+{
+    uint64_t total = 0;
+    for (const auto& [v, c] : plain_counts) total += c;
+    if (total == 0) return false;
+    const uint64_t threshold = (total * 60) / 100;  // floor, as in the oracle
+    auto it = plain_counts.find(successor_version);
+    const uint64_t have = (it == plain_counts.end()) ? 0 : it->second;
+    return have >= threshold;
+}
+
+// v36 activation gate (p2pool-merged-v36 work.py): v36 is active once its
+// WEIGHTED signaling reaches >= 95% of total work. Evaluated as the exact
+// rational w36*100 >= total*95 — integer uint288, no IEEE-double fragility.
+inline bool
+v36_active(const std::map<uint64_t, uint288>& weights, uint64_t v36_version = 36)
+{
+    uint288 total(0);
+    for (const auto& [v, w] : weights) total += w;
+    if (total == uint288(0)) return false;
+    auto it = weights.find(v36_version);
+    uint288 w36 = (it == weights.end()) ? uint288(0) : it->second;
+    return w36 * uint288(100) >= total * uint288(95);
+}
+
+// Window helper mirroring Share.check: negotiation looks at the [9/10 .. 10/10]
+// tail of the CHAIN_LENGTH ancestry behind `prev_hash`. Returns nullopt when
+// fewer than `chain_length` ancestors exist ("switch without enough history").
+struct Window { uint256 start_hash; uint64_t dist; };
+inline std::optional<Window>
+negotiation_window(ShareChain& chain, const uint256& prev_hash, uint64_t chain_length)
+{
+    if (chain.get_height(prev_hash) < static_cast<int64_t>(chain_length))
+        return std::nullopt;
+    const uint64_t back = (chain_length * 9) / 10;
+    const uint64_t dist = chain_length / 10;
+    uint256 start = chain.get_nth_parent_key(prev_hash, static_cast<int32_t>(back));
+    return Window{start, dist};
+}
+
+} // namespace dash::version_negotiation

test/CMakeLists.txt

@@ -213,6 +213,20 @@ if (BUILD_TESTING AND GTest_FOUND)
     target_link_libraries(test_dash_block_replay PRIVATE c2pool_payout c2pool_hashrate c2pool_merged_mining)  # OBJECT-lib SCC direct-naming (#22/#39): core stratum/web_server TUs
     gtest_add_tests(test_dash_block_replay "" AUTO)
 
+    # DASH V36 conformance -- merkle-root-equality precondition (S6 slice).
+    # share_check.hpp (check_merkle_link) + coinbase_builder.hpp
+    # (merkle_branches_raw) are header-only over the dash_x11 + core link set;
+    # no ltc/pool SCC dependency. Mirrors the test_dash_header_chain link set.
+    add_executable(test_dash_conformance test_dash_conformance.cpp)
+    target_link_libraries(test_dash_conformance PRIVATE
+        GTest::gtest_main GTest::gtest
+        dash_x11 core
+        nlohmann_json::nlohmann_json
+        ${Boost_LIBRARIES}
+    )
+    target_link_libraries(test_dash_conformance PRIVATE c2pool_payout c2pool_hashrate c2pool_merged_mining)  # OBJECT-lib SCC direct-naming (#22/#39): core stratum/web_server TUs
+    gtest_add_tests(test_dash_conformance "" AUTO)
+
     add_executable(test_compact_blocks test_compact_blocks.cpp)
     target_link_libraries(test_compact_blocks PRIVATE
         GTest::gtest_main GTest::gtest