dgb: add make_coin_params factory (params.hpp) — Scrypt-only

Builds a fully populated core::CoinParams for the DigiByte-Scrypt p2pool
parent chain. Holds zero hardcoded consensus bytes: every consensus-critical
value is sourced from the single-source-of-truth static members of
dgb::CoinParams (config_coin.hpp) and dgb::PoolConfig (config_pool.hpp).

Sourced from the DGB oracle frstrtr/p2pool-dgb-scrypt (switch-oracle / Option B):
IDENTIFIER 4b62545b1a631afe, PREFIX 1c0553f23ebfcffe, P2P 5024, minproto floor
1700, softforks csv+segwit, version-gated donation (v35 forrestv P2PK / v36 P2SH).

Single-coin scope: touches only src/impl/dgb/.

Author: frstrtr

src/impl/dgb/params.hpp

@@ -0,0 +1,113 @@
+#pragma once
+
+// DGB CoinParams factory: builds a fully populated core::CoinParams for the
+// DigiByte-Scrypt p2pool parent chain.
+//
+// SOURCE OF TRUTH: the DGB oracle frstrtr/p2pool-dgb-scrypt (operator ruling
+// 2026-06-17, "switch-oracle" / Option B). The V36-master byte-compat
+// constraint with p2pool-merged-v36 is FORMALLY WAIVED for DGB by that ruling.
+//
+// CONSENSUS-NEUTRALITY: this factory holds NO hardcoded consensus bytes of its
+// own. Every consensus-critical value is sourced from the single-source-of-truth
+// static members of dgb::CoinParams (config_coin.hpp) and dgb::PoolConfig
+// (config_pool.hpp), so there is exactly one place a DGB constant can drift.
+//
+// Scrypt-only (V36): pow_func = scrypt; other DGB algos are accept-by-continuity
+// per project_v36_dgb_scrypt_only and never reach Scrypt share validation.
+
+#include "config_coin.hpp"
+#include "config_pool.hpp"
+
+#include <core/coin_params.hpp>
+#include <core/pow.hpp>
+
+namespace dgb
+{
+
+inline core::CoinParams make_coin_params(bool testnet)
+{
+    core::CoinParams p;
+
+    // ===== Coin-level (net.PARENT) — from dgb::CoinParams (config_coin.hpp) =====
+    p.symbol       = "DGB";
+    p.block_period = CoinParams::BLOCK_PERIOD;  // 15s (Scrypt algo rotation slot)
+
+    // Address encoding
+    if (testnet) {
+        p.address_version      = CoinParams::TESTNET_ADDRESS_VERSION;  // 126
+        p.address_p2sh_version = CoinParams::TESTNET_P2SH_VERSION;     // 140
+        p.bech32_hrp           = CoinParams::TESTNET_BECH32_HRP;       // "dgbt"
+    } else {
+        p.address_version      = CoinParams::ADDRESS_VERSION;          // 30 (D...)
+        p.address_p2sh_version = CoinParams::ADDRESS_P2SH_VERSION;     // 63 (S...)
+        p.bech32_hrp           = CoinParams::BECH32_HRP;               // "dgb"
+    }
+    // address_p2sh_version2: DGB legacy P2SH prefix (5). Affects address-parse
+    // leniency only, NOT block/share validation. [confirm-vs-oracle]
+    p.address_p2sh_version2 = testnet ? 0 : 5;
+
+    // PoW: Scrypt work, SHA256d block identity (same shape as LTC)
+    p.pow_func        = core::pow::scrypt;
+    p.block_hash_func = core::pow::sha256d;
+
+    // Subsidy: DGB 3-phase decay schedule (config_coin.hpp SSOT)
+    p.subsidy_func = [](uint32_t height) -> uint64_t {
+        return CoinParams::subsidy(height);
+    };
+
+    // Dust threshold: 0.001 DGB. Local relay policy, not consensus. [confirm-vs-oracle]
+    p.dust_threshold = 100000;
+
+    // Softforks — from PoolConfig SSOT (DGB oracle: csv + segwit)
+    p.softforks_required        = PoolConfig::SOFTFORKS_REQUIRED;
+    p.segwit_activation_version = PoolConfig::SEGWIT_ACTIVATION_VERSION;  // 17
+
+    // ===== Pool-level (net) — from dgb::PoolConfig (config_pool.hpp) =====
+    p.p2p_port    = PoolConfig::P2P_PORT;  // 5024 (DGB sharechain P2P)
+    // worker_port: DGB Stratum port. Operator-overridable via pool.yaml; the
+    // default below is provisional pending oracle confirmation. [confirm-vs-oracle]
+    p.worker_port = 5025;
+
+    if (testnet) {
+        p.share_period     = PoolConfig::TESTNET_SHARE_PERIOD;       // 4
+        p.chain_length     = PoolConfig::TESTNET_CHAIN_LENGTH;       // 400
+        p.real_chain_length = PoolConfig::TESTNET_REAL_CHAIN_LENGTH;  // 400
+    } else {
+        p.share_period     = PoolConfig::SHARE_PERIOD;              // 25
+        p.chain_length     = PoolConfig::CHAIN_LENGTH;             // 8640
+        p.real_chain_length = PoolConfig::REAL_CHAIN_LENGTH;        // 8640
+    }
+
+    p.target_lookbehind        = PoolConfig::TARGET_LOOKBEHIND;          // 200
+    p.spread                   = PoolConfig::SPREAD;                     // 30
+    p.minimum_protocol_version = PoolConfig::MINIMUM_PROTOCOL_VERSION;   // 1700 floor
+    p.block_max_size           = PoolConfig::BLOCK_MAX_SIZE;
+    p.block_max_weight         = PoolConfig::BLOCK_MAX_WEIGHT;
+
+    // Max target (share difficulty floor) — PoolConfig SSOT, testnet-aware
+    PoolConfig::is_testnet = testnet;
+    p.max_target = PoolConfig::max_target();
+
+    // Network identification — DGB oracle (switch-oracle Option B)
+    p.identifier_hex         = PoolConfig::IDENTIFIER_HEX;          // 4b62545b1a631afe
+    p.prefix_hex             = PoolConfig::DEFAULT_PREFIX_HEX;      // 1c0553f23ebfcffe
+    p.testnet_identifier_hex = PoolConfig::TESTNET_IDENTIFIER_HEX;
+    p.testnet_prefix_hex     = PoolConfig::TESTNET_PREFIX_HEX;
+
+    // Bootstrap peers (populated as DGB p2pool nodes come online)
+    p.bootstrap_addrs = PoolConfig::DEFAULT_BOOTSTRAP_HOSTS;
+
+    // Donation scripts (consensus-critical) — version-gated selection lives in
+    // PoolConfig::get_donation_script (SSOT). v35 = forrestv P2PK (4104ffd0...),
+    // v36+ = combined P2SH 1-of-2.
+    p.donation_script_func = [](int64_t share_version) -> std::vector<unsigned char> {
+        return PoolConfig::get_donation_script(share_version);
+    };
+
+    p.current_share_version = 36;
+    p.is_testnet            = testnet;
+
+    return p;
+}
+
+} // namespace dgb