dgb: wire embedded mempool tx selection into work template (fees -> coinbasevalue, transactions[])

.github/workflows/build.yml

@@ -69,7 +69,7 @@ jobs:
                     test_address_resolution test_compute_share_target \
                     test_utxo test_dgb_subsidy test_dgb_coinbase_value dgb_share_test dgb_block_assembly_test dgb_header_sample_build_test dgb_header_ingest_test \
                     dgb_gentx_coinbase_test nmc_auxpow_merkle_test nmc_template_builder_test nmc_auxpow_wire_test dgb_gentx_share_path_test dgb_other_tx_resolver_test \
-                    dgb_other_tx_assembler_test dgb_reconstruct_won_block_test dgb_gentx_unpack_test dgb_work_source_test dgb_template_builder_test dgb_embedded_coin_node_test \
+                    dgb_other_tx_assembler_test dgb_reconstruct_won_block_test dgb_gentx_unpack_test dgb_work_source_test dgb_template_builder_test dgb_embedded_coin_node_test dgb_embedded_tx_select_test \
                     rpc_request_test softfork_check_test genesis_check_test algo_select_test digishield_walk_test header_chain_test \
                     dgb_coin_node_seam_test dgb_block_broadcast_test dgb_won_block_dispatch_test \
                     v37_test \
@@ -202,7 +202,7 @@ jobs:
                     test_address_resolution test_compute_share_target \
                     test_utxo test_dgb_subsidy test_dgb_coinbase_value dgb_share_test dgb_block_assembly_test dgb_header_sample_build_test dgb_header_ingest_test \
                     dgb_gentx_coinbase_test nmc_auxpow_merkle_test nmc_template_builder_test nmc_auxpow_wire_test dgb_gentx_share_path_test dgb_other_tx_resolver_test \
-                    dgb_other_tx_assembler_test dgb_reconstruct_won_block_test dgb_gentx_unpack_test dgb_work_source_test dgb_template_builder_test dgb_embedded_coin_node_test \
+                    dgb_other_tx_assembler_test dgb_reconstruct_won_block_test dgb_gentx_unpack_test dgb_work_source_test dgb_template_builder_test dgb_embedded_coin_node_test dgb_embedded_tx_select_test \
                     rpc_request_test softfork_check_test genesis_check_test algo_select_test digishield_walk_test header_chain_test \
                     dgb_coin_node_seam_test dgb_block_broadcast_test dgb_won_block_dispatch_test \
                     test_coin_broadcaster test_multiaddress_pplns test_pplns_stress \

src/impl/dgb/coin/CMakeLists.txt

@@ -26,6 +26,9 @@ set(dgb_coin_interface
     header_chain.hpp
     mempool.hpp
     template_builder.hpp
+    embedded_coinbase_value.hpp
+    embedded_coin_node.hpp
+    embedded_tx_select.hpp embedded_tx_select.cpp
 )
 
 add_library(dgb_coin ${dgb_coin_interface} ${dgb_coin_impl})

src/impl/dgb/coin/embedded_coin_node.hpp

@@ -20,9 +20,13 @@
 //     The external-daemon GBT fallback (NodeRPC::getwork) is a SEPARATE path
 //     and is untouched -- this node is the no-external-daemon source only.
 //   * version pins the Scrypt lane (build_work_template, DGB_BLOCK_VERSION_SCRYPT).
-//   * transactions[] stays empty and total_fees is 0: embedded mempool tx
-//     selection is not wired yet, so the template fabricates no transactions
-//     (the same truthful-absence discipline the stratum caller keeps).
+//   * transactions[] + the fee total come from an injected EmbeddedTxSource
+//     (default empty -> empty transactions[], 0 fees, byte-identical to the
+//     pre-tx-select call site). The production source (embedded_tx_select.cpp,
+//     make_mempool_tx_source) selects fee-sorted mempool txs; their fee total
+//     is folded into coinbasevalue via resolve_coinbase_value (#207), never
+//     fabricated, and transactions[] is passed through build_work_template
+//     verbatim.
 //   * previousblockhash is emitted ONLY when HeaderChain::tip_hash() carries a
 //     real tip id, rendered through the coin/hash_format.hpp SSOT so it is
 //     byte-identical to the stratum caller's previousblockhash.
@@ -39,6 +43,8 @@
 #include <ctime>
 #include <cstdint>
 #include <optional>
+#include <functional>
+#include <utility>
 
 #include <core/pow.hpp>   // core::SubsidyFunc
 
@@ -51,12 +57,37 @@
 namespace dgb::coin
 {
 
+// Caller-supplied embedded transaction selection. Decouples EmbeddedCoinNode
+// from the heavy tx/UTXO codec (mempool.hpp -> transaction.hpp pulls the
+// btclibs serialization templates -- the #143 SCC trap): the node consumes
+// only the ALREADY-SHAPED GBT transactions[] array + the fee total, both plain
+// JSON/integer, so this header stays codec-free and a guard-weight TU that
+// reaches it never compiles the serialization templates. The production shaper
+// lives out-of-line in embedded_tx_select.cpp (make_mempool_tx_source).
+struct EmbeddedTxSelection
+{
+    // GBT transactions[] array, per-tx {data,txid,hash,fee} -- build_work_template
+    // passes it through verbatim. Empty array = no txs selected.
+    nlohmann::json transactions = nlohmann::json::array();
+    // Sum of the known fees across the selected txs, folded into coinbasevalue
+    // via the #207 resolve_coinbase_value SSOT (NOT added to the template here).
+    uint64_t total_fees = 0;
+};
+
+// Injected transaction source. An empty std::function (the default) means NO
+// transaction source is wired: the node emits an empty transactions[] and 0
+// fees -- byte-identical to the pre-tx-select #237 call site. The production
+// wiring injects make_mempool_tx_source(mempool, max_weight).
+using EmbeddedTxSource = std::function<EmbeddedTxSelection()>;
+
 class EmbeddedCoinNode : public CoinNodeInterface
 {
 public:
     EmbeddedCoinNode(c2pool::dgb::HeaderChain& chain,
-                     core::SubsidyFunc        subsidy_func)
-        : m_chain(chain), m_subsidy_func(std::move(subsidy_func))
+                     core::SubsidyFunc        subsidy_func,
+                     EmbeddedTxSource         tx_source = {})
+        : m_chain(chain), m_subsidy_func(std::move(subsidy_func)),
+          m_tx_source(std::move(tx_source))
     {
     }
 
@@ -67,15 +98,26 @@ class EmbeddedCoinNode : public CoinNodeInterface
     {
         const uint32_t height = m_chain.next_block_height();
 
+        // Pull the caller-supplied transaction selection (empty when no source
+        // is wired -> byte-identical to the pre-tx-select template). The heavy
+        // codec that shapes these lives out-of-line (embedded_tx_select.cpp);
+        // this node only folds the fee total into coinbasevalue and passes the
+        // transactions[] array through build_work_template.
+        EmbeddedTxSelection sel;
+        if (m_tx_source)
+            sel = m_tx_source();
+
         WorkTemplateInputs in;
         in.next_height      = height;
-        // Embedded path: no external GBT value -> derive subsidy(height)+fees.
-        // total_fees is 0 until embedded mempool tx selection is wired.
+        // Embedded path: no external GBT value -> derive subsidy(height)+fees
+        // via the #207 SSOT. total_fees comes from the selected txs (0 when no
+        // source is wired).
         in.coinbasevalue    = resolve_coinbase_value(m_subsidy_func, height,
-                                                      /*total_fees=*/0,
+                                                      /*total_fees=*/sel.total_fees,
                                                       /*gbt_coinbasevalue=*/std::nullopt);
         in.median_time_past = m_chain.median_time_past();
         in.curtime          = curtime;
+        in.transactions     = std::move(sel.transactions);
         if (auto th = m_chain.tip_hash())
             in.previousblockhash = u256_be_display_hex(*th);
         return in;
@@ -107,6 +149,7 @@ class EmbeddedCoinNode : public CoinNodeInterface
 private:
     c2pool::dgb::HeaderChain& m_chain;
     core::SubsidyFunc         m_subsidy_func;
+    EmbeddedTxSource          m_tx_source;
 };
 
 } // namespace dgb::coin

src/impl/dgb/coin/embedded_tx_select.cpp

@@ -0,0 +1,64 @@
+// ===========================================================================
+// embedded_tx_select.cpp -- out-of-line shaper for the embedded tx source.
+//
+// The tx/UTXO serialization codec (TX_WITH_WITNESS pack + Hash + HexStr) lives
+// here, NOT in any header, so embedded_coin_node.hpp stays codec-free and the
+// #143 btclibs SCC trap stays shut. Compiled into dgb_coin (which already links
+// the full btclibs serialization), so the codec resolves at link time.
+//
+// Mirrors the per-tx GBT entry shape src/impl/btc/coin/template_builder.hpp
+// emits, so c2pool-dgb and the p2pool-dgb-scrypt reference consume an identical
+// transactions[] form (p2pool reads `fee` in helper.py:123 and adjusts subsidy
+// in data.py:876-884 when a tx is excluded from the share).
+// ===========================================================================
+
+#include "embedded_tx_select.hpp"
+
+#include "transaction.hpp"            // TX_WITH_WITNESS, compute_txid is in mempool.hpp
+
+#include <core/pack.hpp>             // pack
+#include <core/hash.hpp>            // Hash (sha256d)
+#include <btclibs/util/strencodings.h>  // HexStr
+
+#include <string>
+#include <utility>
+
+namespace dgb::coin
+{
+
+EmbeddedTxSource make_mempool_tx_source(Mempool& pool, uint32_t max_weight)
+{
+    return [&pool, max_weight]() -> EmbeddedTxSelection {
+        auto [selected, total_fees] = pool.get_sorted_txs_with_fees(max_weight);
+
+        EmbeddedTxSelection out;
+        out.total_fees = total_fees;
+
+        nlohmann::json tx_array = nlohmann::json::array();
+        for (const auto& stx : selected)
+        {
+            // data  = with-witness serialization hex (what a daemon submits)
+            // txid  = legacy (non-witness) sha256d
+            // hash  = wtxid (with-witness sha256d) for the witness merkle tree
+            const uint256     txid     = compute_txid(stx.tx);
+            auto              packed   = pack(TX_WITH_WITNESS(stx.tx));
+            const std::string hex_data = HexStr(packed.get_span());
+            const uint256     wtxid    = Hash(packed.get_span());
+
+            nlohmann::json entry;
+            entry["data"] = hex_data;
+            entry["txid"] = txid.GetHex();
+            entry["hash"] = wtxid.GetHex();
+            if (stx.fee_known)
+                entry["fee"] = static_cast<int64_t>(stx.fee);
+            else
+                entry["fee"] = nullptr;   // JSON null -> p2pool base_subsidy fallback
+            tx_array.push_back(std::move(entry));
+        }
+
+        out.transactions = std::move(tx_array);
+        return out;
+    };
+}
+
+} // namespace dgb::coin

src/impl/dgb/coin/embedded_tx_select.hpp

@@ -0,0 +1,40 @@
+#pragma once
+// ===========================================================================
+// embedded_tx_select.hpp -- production EmbeddedTxSource factory.
+//
+// Builds the dgb::coin::EmbeddedTxSource that EmbeddedCoinNode injects to fill
+// the embedded work template's transactions[] from the in-process Mempool. The
+// actual shaping (Mempool::SelectedTx -> {data,txid,hash,fee}) is the heavy
+// tx/UTXO serialization codec, so it lives OUT-OF-LINE in embedded_tx_select.cpp
+// (compiled into dgb_coin) -- NOT in this header and NOT in embedded_coin_node.hpp.
+// Keeping the codec in a .cpp is what holds the #143 btclibs SCC trap shut: a
+// guard-weight TU that reaches embedded_coin_node.hpp never compiles the
+// transaction serialization templates.
+//
+// This header DOES pull mempool.hpp (-> transaction.hpp), so include it ONLY
+// from TUs that already link the full dgb_coin codec (main_dgb.cpp + the codec
+// conformance test), never from a guard-weight TU.
+// ===========================================================================
+
+#include <cstdint>
+
+#include "embedded_coin_node.hpp"   // EmbeddedTxSource / EmbeddedTxSelection
+#include "mempool.hpp"              // dgb::coin::Mempool
+
+namespace dgb::coin
+{
+
+// Build an EmbeddedTxSource that, on each invocation, selects up to max_weight
+// BIP141 weight units of fee-sorted transactions from `pool` and shapes them
+// into the GBT transactions[] form build_work_template passes through verbatim:
+//   {data: hex(TX_WITH_WITNESS), txid: txid, hash: wtxid, fee: <int|null>}
+// The returned selection's total_fees is the sum of the known fees across the
+// selected txs (the SAME figure get_sorted_txs_with_fees reports), folded into
+// coinbasevalue by EmbeddedCoinNode via resolve_coinbase_value (#207 SSOT) --
+// NOT added to the template here.
+//
+// `pool` is captured by reference -- it MUST outlive the returned source (the
+// embedded node and its mempool share a lifetime).
+EmbeddedTxSource make_mempool_tx_source(Mempool& pool, uint32_t max_weight);
+
+} // namespace dgb::coin

src/impl/dgb/test/CMakeLists.txt

@@ -201,6 +201,21 @@ if (BUILD_TESTING AND GTest_FOUND)
         nlohmann_json::nlohmann_json)
     gtest_add_tests(dgb_embedded_coin_node_test "" AUTO)
 
+    # dgb_embedded_tx_select_test: guards make_mempool_tx_source
+    # (embedded_tx_select.cpp), the production Mempool -> GBT transactions[]
+    # {data,txid,hash,fee} + fee-total shaper EmbeddedCoinNode injects. Compiles
+    # the tx serialization codec, so it links the same proven SCC set as
+    # dgb_embedded_coin_node_test. MUST also be in BOTH build.yml --target
+    # allowlists (#143 NOT_BUILT trap).
+    add_executable(dgb_embedded_tx_select_test embedded_tx_select_test.cpp)
+    target_link_libraries(dgb_embedded_tx_select_test PRIVATE
+        GTest::gtest_main GTest::gtest
+        core dgb dgb_stratum
+        c2pool_payout c2pool_merged_mining c2pool_hashrate c2pool_storage
+        dgb_coin pool sharechain
+        nlohmann_json::nlohmann_json)
+    gtest_add_tests(dgb_embedded_tx_select_test "" AUTO)
+
 
     foreach(dgb_guard rpc_request_test softfork_check_test genesis_check_test algo_select_test digishield_walk_test)
         add_executable(${dgb_guard} ${dgb_guard}.cpp)

src/impl/dgb/test/embedded_coin_node_test.cpp

@@ -135,3 +135,44 @@ TEST(DgbEmbeddedCoinNode, GetworkProducesTemplateWithNoFabrication)
     EXPECT_TRUE(wd.m_hashes.empty());            // no tx hashes fabricated
     EXPECT_FALSE(node.is_synced());              // truthful: not synced yet
 }
+
+// 5. Injected tx source: the fee total folds into coinbasevalue via the #207
+//    SSOT and transactions[] passes through build_work_template verbatim.
+//    Codec-free: a stub source supplies an ALREADY-SHAPED selection, exactly
+//    as make_mempool_tx_source would, so this guard never compiles the tx
+//    serialization codec (the embedded_tx_select.cpp / dgb_embedded_tx_select_test
+//    pins the real shaping over a Mempool).
+TEST(DgbEmbeddedCoinNode, InjectedTxSourceFoldsFeesAndPassesTransactions)
+{
+    HeaderChain hc;
+    hc.validate_and_append(HeaderSample{SCRYPT, 1000, 100});
+
+    nlohmann::json txs = nlohmann::json::array();
+    nlohmann::json e1; e1["data"]="00"; e1["txid"]="aa"; e1["hash"]="aa"; e1["fee"]=700;
+    nlohmann::json e2; e2["data"]="01"; e2["txid"]="bb"; e2["hash"]="bb"; e2["fee"]=300;
+    txs.push_back(e1); txs.push_back(e2);
+    const uint64_t fees = 1000;
+
+    EmbeddedCoinNode node(hc, make_subsidy(),
+        [txs, fees]() -> dgb::coin::EmbeddedTxSelection { return {txs, fees}; });
+
+    const uint32_t h = hc.next_block_height();
+    const nlohmann::json t = build_work_template(node.make_inputs(7));
+    EXPECT_EQ(t["coinbasevalue"].get<uint64_t>(), 1000ull + h + fees); // subsidy(h)+fees
+    EXPECT_EQ(t["transactions"], txs);                                 // verbatim pass-through
+    EXPECT_EQ(t["transactions"].size(), 2u);
+}
+
+// 6. Empty (default) tx source == byte-identical to the no-source template
+//    (the #237 call-site invariant: a node with no tx source fabricates nothing).
+TEST(DgbEmbeddedCoinNode, EmptyTxSourceByteIdenticalToNoSource)
+{
+    HeaderChain hc;
+    hc.validate_and_append(HeaderSample{SCRYPT, 1000, 100});
+
+    EmbeddedCoinNode no_src(hc, make_subsidy());
+    EmbeddedCoinNode empty_src(hc, make_subsidy(), dgb::coin::EmbeddedTxSource{});
+
+    EXPECT_EQ(build_work_template(empty_src.make_inputs(5)).dump(),
+              build_work_template(no_src.make_inputs(5)).dump());
+}