dgb: Stage 4c — wire get_current_work_template coinbasevalue through #207 SSOT

src/impl/dgb/stratum/work_source.cpp

@@ -148,11 +148,26 @@ void DGBWorkSource::update_stratum_worker(const std::string& session_id,
 
 nlohmann::json DGBWorkSource::get_current_work_template() const
 {
-    // Stage 4c: drive dgb::coin::TemplateBuilder over chain_ + mempool_ and
-    // shape its WorkData into the GBT-style JSON the stratum session expects
-    // (previousblockhash, bits, version, curtime, mintime, height,
-    // coinbasevalue, transactions[]). Scrypt nBits, not SHA256d.
-    return nlohmann::json::object();
+    // Stage 4c (coinbasevalue wire): the full GBT-shaped template
+    // (previousblockhash, bits, version, curtime, mintime, transactions[])
+    // is assembled by the embedded dgb::coin::TemplateBuilder in a following
+    // slice. What lands here is the consensus-bearing reward field: the
+    // coinbasevalue for the NEXT block, derived through the #207 SSOT
+    // (coinbase_value -> resolve_coinbase_value -> subsidy_func) keyed on the
+    // absolute next-block height from the #209 HeaderChain accessor
+    // (next_block_height() == tip_height()+1, or base_height for an empty
+    // chain). Embedded path: no external-daemon GBT value is plumbed in yet
+    // and mempool-fee aggregation is not wired, so total_fees = 0 here. Both
+    // compose in later slices WITHOUT changing this SSOT call (a present GBT
+    // coinbasevalue stays authoritative; fees add on top of subsidy).
+    const uint32_t next_h = chain_.next_block_height();
+    const uint64_t coinbasevalue =
+        coinbase_value(next_h, /*total_fees=*/0, /*gbt_coinbasevalue=*/std::nullopt);
+
+    nlohmann::json tmpl = nlohmann::json::object();
+    tmpl["height"]        = next_h;
+    tmpl["coinbasevalue"] = coinbasevalue;
+    return tmpl;
 }
 
 std::vector<std::string> DGBWorkSource::get_stratum_merkle_branches() const

src/impl/dgb/test/work_source_test.cpp

@@ -135,8 +135,10 @@ TEST(DgbWorkSource, WorkGenStubsReturnSafeDefaults)
     // 4a skeleton: every work-generation getter returns its documented
     // empty/default form (4c fills them in).
     EXPECT_TRUE(ws->get_current_gbt_prevhash().empty());
+    // get_current_work_template() now emits height + coinbasevalue (Stage 4c
+    // coinbasevalue wire); its dedicated assertions live in
+    // WorkTemplateEmitsHeightAndCoinbaseValueViaSsot below.
     EXPECT_TRUE(ws->get_current_work_template().is_object());
-    EXPECT_TRUE(ws->get_current_work_template().empty());
     EXPECT_TRUE(ws->get_stratum_merkle_branches().empty());
     auto parts = ws->get_coinbase_parts();
     EXPECT_TRUE(parts.first.empty());
@@ -174,6 +176,26 @@ TEST(DgbWorkSource, ComputeShareDifficultyReturnsNotYetSentinel)
     EXPECT_DOUBLE_EQ(diff, 0.0);
 }
 
+// Stage 4c coinbasevalue wire: the work template surfaces the NEXT-block
+// height and its coinbasevalue, the latter derived THROUGH the #207 SSOT
+// (subsidy_func) keyed on next_block_height() == tip.height + 1 (#209). An
+// empty chain makes next_block_height() == base_height, so seeding an oracle
+// era boundary pins the value unambiguously to the p2pool-dgb-scrypt subsidy.
+TEST(DgbWorkSource, WorkTemplateEmitsHeightAndCoinbaseValueViaSsot)
+{
+    Fixture fx;
+    fx.chain.set_base_height(400000);  // phase3 first block (oracle boundary)
+    auto ws = fx.make();
+    auto tmpl = ws->get_current_work_template();
+    ASSERT_TRUE(tmpl.is_object());
+    ASSERT_TRUE(tmpl.contains("height"));
+    ASSERT_TRUE(tmpl.contains("coinbasevalue"));
+    // next_h = next_block_height() = base_height (empty chain) = 400000.
+    EXPECT_EQ(tmpl["height"].get<uint32_t>(), 400000u);
+    // Zero embedded fees, no external GBT -> oracle subsidy at the boundary.
+    EXPECT_EQ(tmpl["coinbasevalue"].get<uint64_t>(), 2434410000ULL);
+}
+
 // ── Embedded coinbasevalue: first production caller of subsidy_func ──────────
 // One pin on each side of every DGB reward-era boundary (p2pool-dgb-scrypt
 // oracle vectors, test_dgb_subsidy.cpp).