dash(S8): get_work() consumer capstone -- fuse NodeCoinState::select_work() template source + assemble_work_job_targets()

The embedded get_work chain was fully wired but had NO production consumer:
NodeCoinState::select_work() (embedded template when the 4-leg reception wire
(#693/#694) has populated the node bundle, else the retained dashd
getblocktemplate fallback) and assemble_work_job_targets() (per-miner job-target
arithmetic) each existed and were unit-tested, but nothing fused them into a
single miner-facing entry. Only the test suites ever called select_work().

Add dash::stratum::get_work() (src/impl/dash/stratum/get_work.hpp): the first
non-test caller of the embedded arm. It sources the base block template off the
node-held NodeCoinState -- NO direct dashd poll on the hot path when the bundle
is populated -- and assembles the job targets over whichever template arm ran.
dashd_fallback stays REQUIRED and is invoked ONLY on a set-gap (unpopulated /
invalidated bundle): the always-reachable safety + [GBT-XCHECK] cross-check arm,
never removed.

test_dash_get_work (4/4) pins the fused contract, seeding mirrored exactly from
test_dash_node_embedded_wire (no fabricated oracle values):
  * set-gap routes DashdFallback (invoked once) and still assembles targets;
  * populated routes Embedded WITHOUT invoking the fallback, byte-equal to a
    direct build_embedded_workdata() over the node's own held state;
  * job targets are identical across both template sources;
  * on_invalidate (reorg) demotes back to the fallback.

Registered in both build.yml --target allowlists. STRICTLY single-coin
(src/impl/dash/ + test only), SAFE-ADDITIVE.

Author: frstrtr

.github/workflows/build.yml

@@ -102,7 +102,7 @@ jobs:
                     core_test sharechain_test share_test btc_share_test \
                     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_conformance test_dash_subsidy test_dash_mempool test_dash_simplifiedmns test_dash_quorum test_dash_quorum_root test_dash_mn_state test_dash_embedded_gbt test_dash_smldiff test_dash_p2p_messages test_dash_p2p_connection test_dash_p2p_node test_dash_node_interface test_dash_config test_dash_broadcaster test_dash_broadcaster_full test_dash_share_hash_link test_dash_block_relay test_dash_rpc_request test_dash_rpc_conf test_dash_block_producer test_dash_embedded_relay_e2e test_dash_block_relay_plan test_dash_version_activation_latch test_dash_block_relay_binding test_dash_block_relay_dual_arm test_dash_coinbase_parity test_dash_donation_combined test_dash_g3_assembled test_dash_work_target test_dash_work_job_targets test_dash_stratum_binding test_dash_job_notify_roundtrip test_dash_cb_payee test_dash_stratum_notify_roundtrip test_dash_poolnode_messages test_dash_peer test_dash_share_tracker test_dash_node test_dash_share_messages test_dash_stratum_extranonce_split test_dash_stratum_submit_reassembly test_dash_difficulty_parity test_dash_auto_ratchet test_dash_min_protocol_gate test_dash_work_source test_dash_node_coin_state test_dash_coin_state_maintainer test_dash_node_embedded_wire test_dash_node_reception_wire \
+                    test_doge_chain test_compact_blocks test_dash_x11_kat test_dash_header_chain test_dash_block_replay test_dash_conformance test_dash_subsidy test_dash_mempool test_dash_simplifiedmns test_dash_quorum test_dash_quorum_root test_dash_mn_state test_dash_embedded_gbt test_dash_smldiff test_dash_p2p_messages test_dash_p2p_connection test_dash_p2p_node test_dash_node_interface test_dash_config test_dash_broadcaster test_dash_broadcaster_full test_dash_share_hash_link test_dash_block_relay test_dash_rpc_request test_dash_rpc_conf test_dash_block_producer test_dash_embedded_relay_e2e test_dash_block_relay_plan test_dash_version_activation_latch test_dash_block_relay_binding test_dash_block_relay_dual_arm test_dash_coinbase_parity test_dash_donation_combined test_dash_g3_assembled test_dash_work_target test_dash_work_job_targets test_dash_stratum_binding test_dash_job_notify_roundtrip test_dash_cb_payee test_dash_stratum_notify_roundtrip test_dash_poolnode_messages test_dash_peer test_dash_share_tracker test_dash_node test_dash_share_messages test_dash_stratum_extranonce_split test_dash_stratum_submit_reassembly test_dash_difficulty_parity test_dash_auto_ratchet test_dash_min_protocol_gate test_dash_work_source test_dash_node_coin_state test_dash_coin_state_maintainer test_dash_node_embedded_wire test_dash_node_reception_wire test_dash_get_work \
                     test_multiaddress_pplns test_pplns_stress \
                     test_hash_link test_decay_pplns \
                     test_pplns_consensus \
@@ -252,7 +252,7 @@ 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_conformance test_dash_subsidy test_dash_mempool test_dash_simplifiedmns test_dash_quorum test_dash_quorum_root test_dash_mn_state test_dash_embedded_gbt test_dash_smldiff test_dash_p2p_messages test_dash_p2p_connection test_dash_p2p_node test_dash_node_interface test_dash_config test_dash_broadcaster test_dash_broadcaster_full test_dash_share_hash_link test_dash_block_relay test_dash_rpc_request test_dash_rpc_conf test_dash_block_producer test_dash_embedded_relay_e2e test_dash_block_relay_plan test_dash_version_activation_latch test_dash_block_relay_binding test_dash_block_relay_dual_arm test_dash_coinbase_parity test_dash_donation_combined test_dash_g3_assembled test_dash_work_target test_dash_work_job_targets test_dash_stratum_binding test_dash_job_notify_roundtrip test_dash_cb_payee test_dash_stratum_notify_roundtrip test_dash_poolnode_messages test_dash_peer test_dash_share_tracker test_dash_node test_dash_share_messages test_dash_stratum_extranonce_split test_dash_stratum_submit_reassembly test_dash_difficulty_parity test_dash_auto_ratchet test_dash_min_protocol_gate test_dash_work_source test_dash_node_coin_state test_dash_coin_state_maintainer test_dash_node_embedded_wire test_dash_node_reception_wire \
+                    test_dash_header_chain test_dash_block_replay test_dash_conformance test_dash_subsidy test_dash_mempool test_dash_simplifiedmns test_dash_quorum test_dash_quorum_root test_dash_mn_state test_dash_embedded_gbt test_dash_smldiff test_dash_p2p_messages test_dash_p2p_connection test_dash_p2p_node test_dash_node_interface test_dash_config test_dash_broadcaster test_dash_broadcaster_full test_dash_share_hash_link test_dash_block_relay test_dash_rpc_request test_dash_rpc_conf test_dash_block_producer test_dash_embedded_relay_e2e test_dash_block_relay_plan test_dash_version_activation_latch test_dash_block_relay_binding test_dash_block_relay_dual_arm test_dash_coinbase_parity test_dash_donation_combined test_dash_g3_assembled test_dash_work_target test_dash_work_job_targets test_dash_stratum_binding test_dash_job_notify_roundtrip test_dash_cb_payee test_dash_stratum_notify_roundtrip test_dash_poolnode_messages test_dash_peer test_dash_share_tracker test_dash_node test_dash_share_messages test_dash_stratum_extranonce_split test_dash_stratum_submit_reassembly test_dash_difficulty_parity test_dash_auto_ratchet test_dash_min_protocol_gate test_dash_work_source test_dash_node_coin_state test_dash_coin_state_maintainer test_dash_node_embedded_wire test_dash_node_reception_wire test_dash_get_work \
                     test_hash_link test_decay_pplns \
                     test_pplns_consensus \
                     test_v36_script_sorting test_v36_cross_impl_refhash \

src/impl/dash/stratum/get_work.hpp

@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: AGPL-3.0-or-later
+#pragma once
+
+/// Phase C-TEMPLATE step 9 (capstone): the fused dash get_work() consumer.
+///
+/// Every prior slice landed one HALF of get_work in isolation:
+///   * select_dash_work() / NodeCoinState::select_work() (work_source.hpp,
+///     node_coin_state.hpp, #672/#673) -- the TEMPLATE source: prefer the
+///     locally-assembled embedded template (build_embedded_workdata, oracle
+///     parity vs frstrtr/p2pool-dash getwork(), older-than-v35) when the
+///     node-held coin-state bundle is populated by the 4-leg reception wire
+///     (#693/#694), else the RETAINED dashd getblocktemplate fallback;
+///   * assemble_work_job_targets() (work_job_targets.hpp) -- the per-miner
+///     JOB-TARGET arithmetic (work.py:368-426).
+///
+/// Nothing fused them: no production (non-test) caller ever ran
+/// NodeCoinState::select_work() to source a template AND assembled the miner
+/// job over it -- the two halves were exercised only by their own unit KATs.
+/// get_work() is that single miner-facing entry point -- the
+/// "DASHWorkSource::get_work()" the stratum headers reference as future work.
+///
+/// CONTRACT (matches the S8 embedded-arm invariants):
+///   * the hot path reads the node-held NodeCoinState -- NO direct dashd poll
+///     when the bundle is populated (the embedded arm assembles locally);
+///   * dashd_fallback is REQUIRED and is invoked ONLY on a set-gap
+///     (unpopulated / invalidated bundle) -- the always-reachable safety path
+///     and the [GBT-XCHECK] cross-check, NEVER removed;
+///   * the job-target assembly is a pure transform of caller inputs and rides
+///     on top of EITHER template source unchanged.
+///
+/// STRICTLY single-coin: src/impl/dash/ only, no bitcoin_family / src/core
+/// reach beyond the shared uint256/DashWorkData types the halves already use.
+
+#include <impl/dash/coin/node_coin_state.hpp>       // NodeCoinState, WorkSelection, WorkSource
+#include <impl/dash/coin/rpc_data.hpp>              // DashWorkData
+#include <impl/dash/stratum/work_job_targets.hpp>   // assemble_work_job_targets, WorkJobTargets, WorkJobTargetInputs
+
+#include <functional>
+#include <utility>
+
+namespace dash::stratum {
+
+/// The miner-facing result of get_work(): which arm sourced the template, the
+/// selected block template itself, and the assembled stratum job targets.
+struct GetWork {
+    coin::WorkSource   source{coin::WorkSource::DashdFallback};
+    coin::DashWorkData work;
+    WorkJobTargets     targets;
+};
+
+/// Fused get_work(): source the base block template off the node-held
+/// coin-state (embedded when populated, retained dashd fallback on a set-gap)
+/// and assemble the per-miner job targets over it. dashd_fallback is REQUIRED
+/// -- it is the always-reachable safety/cross-check arm and is only invoked
+/// when the embedded bundle is unavailable.
+inline GetWork get_work(
+    const coin::NodeCoinState& coin_state,
+    const std::function<coin::DashWorkData()>& dashd_fallback,
+    const WorkJobTargetInputs& job_in)
+{
+    coin::WorkSelection sel = coin_state.select_work(dashd_fallback);
+    WorkJobTargets targets  = assemble_work_job_targets(job_in);
+    return GetWork{ sel.source, std::move(sel.work), targets };
+}
+
+}  // namespace dash::stratum

test/CMakeLists.txt

@@ -559,6 +559,17 @@ if (BUILD_TESTING AND GTest_FOUND)
     )
     target_link_libraries(test_dash_node_embedded_wire PRIVATE c2pool_payout c2pool_hashrate c2pool_merged_mining c2pool_storage pool)  # OBJECT-lib SCC direct-naming (#22/#39)
     gtest_add_tests(test_dash_node_embedded_wire "" AUTO)
+    # get_work() consumer capstone: fuses NodeCoinState::select_work() (embedded
+    # template source) with assemble_work_job_targets(); same OBJECT-lib SCC.
+    add_executable(test_dash_get_work test_dash_get_work.cpp)
+    target_link_libraries(test_dash_get_work PRIVATE
+        GTest::gtest_main GTest::gtest
+        dash_x11 core
+        nlohmann_json::nlohmann_json
+        ${Boost_LIBRARIES}
+    )
+    target_link_libraries(test_dash_get_work PRIVATE c2pool_payout c2pool_hashrate c2pool_merged_mining c2pool_storage pool)  # OBJECT-lib SCC direct-naming (#22/#39)
+    gtest_add_tests(test_dash_get_work "" AUTO)
 
     # Reception wire (legs 1-3): interfaces::Node reception Events ->
     # CoinStateMaintainer. Proves the wire_*_ingest() subscriptions fold off the