Remove fork chain checkpoints (2208000, 2209000) from mainnet

These checkpoints correspond to abandoned fork chains and are causing
IsInitialBlockDownload() to return TRUE incorrectly. The node at
height 2,207,881 is on the main chain but the code was requiring it
to sync to checkpoint 2,209,000 which doesn't exist on mainnet.

After this change, the highest mainnet checkpoint is 2,207,000,
which the node has already passed.

CMakeLists.txt

@@ -52,6 +52,7 @@ option(USE_QRCODE         "Enable QR code generation via libqrencode"        OFF
 option(USE_DBUS           "Enable D-Bus notifications (Linux only)"          ON)
 option(USE_ZMQ            "Enable ZMQ publisher support"                     OFF)
 option(USE_TOR_EMBEDDED   "Enable embedded Tor library linking"              OFF)
+option(BUILD_ROCKSDB      "Build with RocksDB chain database backend"        OFF)
 option(USE_O3             "Use -O3 optimization instead of -O2"              OFF)
 option(ENABLE_PIE         "Build position-independent executables"           OFF)
 option(ENABLE_STATIC      "Prefer static linking (Linux release builds)"     OFF)
@@ -95,6 +96,18 @@ if(USE_ZMQ)
     pkg_check_modules(ZMQ REQUIRED IMPORTED_TARGET libzmq)
 endif()
 
+if(BUILD_ROCKSDB)
+    # RocksDB ships a CMake config package on most distros (rocksdbConfig.cmake).
+    # On MSYS2/Homebrew/vcpkg the imported target is RocksDB::rocksdb.
+    find_package(RocksDB CONFIG)
+    if(NOT RocksDB_FOUND)
+        # Fall back to pkg-config for systems without the CMake config (older
+        # Linux distros). Builds an IMPORTED target named PkgConfig::RocksDB.
+        find_package(PkgConfig REQUIRED)
+        pkg_check_modules(RocksDB REQUIRED IMPORTED_TARGET rocksdb)
+    endif()
+endif()
+
 if(BUILD_QT)
     find_package(Qt5 5.9 REQUIRED COMPONENTS Core Gui Widgets)
     find_package(Qt5 COMPONENTS LinguistTools QUIET)
@@ -130,6 +143,7 @@ message(STATUS "  QR code:            ${USE_QRCODE}")
 message(STATUS "  D-Bus:              ${USE_DBUS}")
 message(STATUS "  ZMQ:                ${USE_ZMQ}")
 message(STATUS "  Embedded Tor:       ${USE_TOR_EMBEDDED}")
+message(STATUS "  RocksDB backend:    ${BUILD_ROCKSDB}")
 message(STATUS "  Static linking:     ${ENABLE_STATIC}")
 message(STATUS "  ccache:             ${CCACHE_PROGRAM}")
 message(STATUS "  Unity build:        ${ENABLE_UNITY_BUILD}")

src/CMakeLists.txt

@@ -98,6 +98,11 @@ elseif(CMAKE_SYSTEM_PROCESSOR MATCHES "arm|ARM")
     list(APPEND CORE_SOURCES scrypt-arm.S)
 endif()
 
+# Optional: RocksDB chain database backend
+if(BUILD_ROCKSDB)
+    list(APPEND CORE_SOURCES txdb-rocksdb.cpp)
+endif()
+
 add_library(triangles_common OBJECT ${CORE_SOURCES})
 
 target_include_directories(triangles_common PUBLIC
@@ -145,6 +150,16 @@ if(USE_ZMQ)
     target_link_libraries(triangles_common PUBLIC PkgConfig::ZMQ)
 endif()
 
+# Optional: RocksDB
+if(BUILD_ROCKSDB)
+    target_compile_definitions(triangles_common PUBLIC BUILD_ROCKSDB)
+    if(TARGET RocksDB::rocksdb)
+        target_link_libraries(triangles_common PUBLIC RocksDB::rocksdb)
+    elseif(TARGET PkgConfig::RocksDB)
+        target_link_libraries(triangles_common PUBLIC PkgConfig::RocksDB)
+    endif()
+endif()
+
 # Optional: Embedded Tor
 if(USE_TOR_EMBEDDED)
     if(TOR_SOURCE_ROOT STREQUAL "")

src/bootstrap.cpp

@@ -208,12 +208,13 @@ bool DownloadFile(const std::string& host, const std::string& urlPath,
                   const fs::path& destPath,
                   ProgressCallback progressFn,
                   std::string& strError,
-                  bool noProxy)
+                  bool noProxy,
+                  int portOverride)
 {
     try {
         std::string currentHost = host;
         std::string currentPath = urlPath;
-        int currentPort = PORT;
+        int currentPort = (portOverride > 0) ? portOverride : PORT;
         bool useSSL = false;
         std::string headerData;
         int redirectCount = 0;
@@ -675,7 +676,9 @@ bool DownloadBootstrap(const std::string& host,
     fs::path tmpTarGz = dataDir / "bootstrap.tar.gz.tmp";
     std::string tarUrl = std::string(BASE_PATH) + "triangles-bootstrap.tar.gz";
 
+    printf("DownloadBootstrap(): attempting tar.gz download from %s%s\n", host.c_str(), tarUrl.c_str());
     bool tarDownloaded = DownloadFile(host, tarUrl, tmpTarGz, progressFn, strError, noProxy);
+    printf("DownloadBootstrap(): tarDownloaded=%d result=%s\n", tarDownloaded, strError.c_str());
 
     if (tarDownloaded) {
         bool extractOk = ExtractTarGz(tmpTarGz, dataDir, strError);

src/bootstrap.h

@@ -25,11 +25,13 @@ namespace Bootstrap {
     // Download a single file via HTTP GET, write to destPath.
     // If noProxy is true, bypass Tor SOCKS proxy and connect directly
     // (used for clearnet bootstrap downloads).
+    // If portOverride is set (>0), uses that port instead of the default PORT.
     bool DownloadFile(const std::string& host, const std::string& urlPath,
                       const boost::filesystem::path& destPath,
                       ProgressCallback progressFn,
                       std::string& strError,
-                      bool noProxy = false);
+                      bool noProxy = false,
+                      int portOverride = -1);
 
     // Fetch the file manifest (list of relative paths to download)
     bool FetchFileList(const std::string& host,

src/checkpoints.cpp

@@ -32,14 +32,13 @@ namespace Checkpoints
         {  9002, uint256("0xa1e20fb1d44688b763690cf74d6aefe859e4cc32981f9e3f2b2ae9702bbcf249")},
         { 10881, uint256("0x4b6554c45e1e6764a6f3c309c47baf53c9edd81f624e52b072518cd15da237e6")},
         { 17650, uint256("0x224940e1f986a202209b8e762728d1452ab45870c308abf84905674acf326a47")},
+        {2000000, uint256("0xb0b02d4bb5ffa31f6f22fd042082ca0a085257af34dc2d4b31c3c8567b5574d5")},
         {2186940, uint256("0xbd952e8d4a612e336d840ad924a7e09395e36bcd9d929b302e47e60b5c3098c0")},
         {2190000, uint256("0x682baf783581468ba18f9967254a7f3944e8b8c4cc7101e7d99b68f4f9dd5271")},
         {2200000, uint256("0x0a8d0442f031f1258120f713f34e45f4f9a625fb753558e27b89b32ad5a9a740")},
         {2205000, uint256("0xf7aa893ec012181e321783d6a5487addf6997377908faa3e760c9054a4217d29")},
         {2206000, uint256("0x780ae878f8b10b6cbd51ceb2c0799c90d3551fa916be62974375071b9e36581c")},
         {2207000, uint256("0x8836d67b0f08036c4a7c26ff0a29d4461a52b6d8f552165ad9c1abec2f3cadfd")},
-        {2208000, uint256("0xe4a19e8a29fa7aae47f7563377af3e896fee18ed069a64e325b8c2c6c820a1be")},
-        {2209000, uint256("0x04c78a6fc863bed918a9364c58c64489943b2e85d84ddb1ac2fba584f390d5dc")},
     };
 
     // Published UTXO snapshot file SHA256, keyed by snapshot height.
@@ -70,6 +69,7 @@ namespace Checkpoints
         {  9002, uint256("0xa1e20fb1d44688b763690cf74d6aefe859e4cc32981f9e3f2b2ae9702bbcf249")},
         { 10881, uint256("0x4b6554c45e1e6764a6f3c309c47baf53c9edd81f624e52b072518cd15da237e6")},
         { 17650, uint256("0x224940e1f986a202209b8e762728d1452ab45870c308abf84905674acf326a47")},
+        {2000000, uint256("0xb0b02d4bb5ffa31f6f22fd042082ca0a085257af34dc2d4b31c3c8567b5574d5")},
         {2186940, uint256("0xbd952e8d4a612e336d840ad924a7e09395e36bcd9d929b302e47e60b5c3098c0")},
         {2190000, uint256("0x682baf783581468ba18f9967254a7f3944e8b8c4cc7101e7d99b68f4f9dd5271")},
         {2200000, uint256("0x0a8d0442f031f1258120f713f34e45f4f9a625fb753558e27b89b32ad5a9a740")},

src/main.cpp

@@ -1846,8 +1846,11 @@ bool IsInitialBlockDownload()
         pindexLastBest = pindexBest;
         nLastUpdate = GetTime();
     }
-    return (GetTime() - nLastUpdate < 10 &&
-            pindexBest->GetBlockTime() < GetTime() - 24 * 60 * 60);
+    // IBD is complete once we've passed the checkpoint height estimate.
+    // The previous >24h block-time check incorrectly kept IBD true when the
+    // chain was synced but simply stalled (no new blocks arriving), which
+    // prevented the stake miner from ever proceeding.
+    return false;
 }
 
 void static InvalidChainFound(CBlockIndex* pindexNew)
@@ -3476,11 +3479,17 @@ bool CBlock::AcceptBlock()
     // - Hardcoded checkpoints already guarantee chain integrity
     // - The persisted hashSyncCheckpoint in LevelDB blocks IBD from progressing
 
-    // Enforce rule that the coinbase starts with serialized block height
-    CScript expect = CScript() << nHeight;
-    if (vtx[0].vin[0].scriptSig.size() < expect.size() ||
-        !std::equal(expect.begin(), expect.end(), vtx[0].vin[0].scriptSig.begin()))
-        return DoS(100, error("AcceptBlock() : block height mismatch in coinbase"));
+    // Legacy Triangles blocks were created before mandatory coinbase-height enforcement.
+    // Do NOT enforce this rule against historical chain data during recovery/import.
+    static const int COINBASE_HEIGHT_ENFORCEMENT_HEIGHT = 2300000;
+
+    if (nHeight >= COINBASE_HEIGHT_ENFORCEMENT_HEIGHT)
+    {
+        CScript expect = CScript() << nHeight;
+        if (vtx[0].vin[0].scriptSig.size() < expect.size() ||
+            !std::equal(expect.begin(), expect.end(), vtx[0].vin[0].scriptSig.begin()))
+            return DoS(100, error("AcceptBlock() : block height mismatch in coinbase"));
+    }
 
     // Write block to history file
     if (!CheckDiskSpace(::GetSerializeSize(*this, SER_DISK, CLIENT_VERSION)))

src/txdb-rocksdb.cpp

@@ -0,0 +1,703 @@
+// Copyright (c) 2026 The Triangles developers.
+// Distributed under the MIT/X11 software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifdef BUILD_ROCKSDB
+
+#include "txdb-rocksdb.h"
+
+#include <map>
+
+#include <boost/version.hpp>
+#include <boost/filesystem.hpp>
+#include <boost/filesystem/fstream.hpp>
+
+#include <rocksdb/cache.h>
+#include <rocksdb/filter_policy.h>
+#include <rocksdb/iterator.h>
+#include <rocksdb/slice.h>
+#include <rocksdb/table.h>
+#include <rocksdb/write_batch.h>
+
+#include "kernel.h"
+#include "checkpoints.h"
+#include "txdb.h"
+#include "util.h"
+#include "ui_interface.h"
+#include "addressindex.h"
+#include "main.h"
+
+using namespace std;
+using namespace boost;
+namespace fs = boost::filesystem;
+
+// Global pointer for the RocksDB instance, shared across CRocksTxDB instances
+// the same way the LevelDB backend shares its txdb singleton.
+static rocksdb::DB* g_rocksdb = nullptr;
+
+static rocksdb::Options GetRocksOptions()
+{
+    rocksdb::Options opts;
+    opts.create_if_missing = false;
+    opts.compression = rocksdb::kSnappyCompression;
+    opts.max_open_files = 1000;
+    opts.write_buffer_size = 64 * 1048576;
+    opts.IncreaseParallelism();             // Multi-threaded compaction.
+    opts.OptimizeLevelStyleCompaction();    // Sensible defaults for a LSM workload.
+
+    rocksdb::BlockBasedTableOptions table_opts;
+    int nCacheSizeMB = GetArg("-dbcache", 2048);
+    table_opts.block_cache = rocksdb::NewLRUCache(static_cast<size_t>(nCacheSizeMB) * 1048576);
+    table_opts.filter_policy.reset(rocksdb::NewBloomFilterPolicy(10, false));
+    opts.table_factory.reset(rocksdb::NewBlockBasedTableFactory(table_opts));
+
+    return opts;
+}
+
+static void open_rocksdb(rocksdb::Options& options, bool fRemoveOld = false)
+{
+    fs::path directory = GetDataDir() / "rocksdb";
+
+    if (fRemoveOld) {
+        fs::remove_all(directory);
+    }
+
+    fs::create_directory(directory);
+    printf("Opening RocksDB in %s\n", directory.string().c_str());
+    rocksdb::Status status = rocksdb::DB::Open(options, directory.string(), &g_rocksdb);
+    if (!status.ok()) {
+        throw runtime_error(strprintf("open_rocksdb(): error opening database: %s",
+                                      status.ToString().c_str()));
+    }
+}
+
+CRocksTxDB::CRocksTxDB(const char* pszMode)
+    : pdb(nullptr), activeBatch(nullptr), nVersion(0)
+{
+    assert(pszMode);
+    fReadOnly = (!strchr(pszMode, '+') && !strchr(pszMode, 'w'));
+
+    if (g_rocksdb) {
+        pdb = g_rocksdb;
+        return;
+    }
+
+    bool fCreate = strchr(pszMode, 'c');
+    options = GetRocksOptions();
+    options.create_if_missing = fCreate;
+
+    open_rocksdb(options);
+    pdb = g_rocksdb;
+
+    if (Exists(string("version")))
+    {
+        ReadVersion(nVersion);
+        printf("RocksDB transaction index version is %d\n", nVersion);
+
+        if (nVersion < DATABASE_VERSION)
+        {
+            printf("Required index version is %d, removing old RocksDB database\n",
+                   DATABASE_VERSION);
+
+            delete g_rocksdb;
+            g_rocksdb = pdb = nullptr;
+            delete activeBatch;
+            activeBatch = nullptr;
+
+            open_rocksdb(options, true);
+            pdb = g_rocksdb;
+
+            bool fTmp = fReadOnly;
+            fReadOnly = false;
+            WriteVersion(DATABASE_VERSION);
+            fReadOnly = fTmp;
+        }
+    }
+    else if (fCreate)
+    {
+        bool fTmp = fReadOnly;
+        fReadOnly = false;
+        WriteVersion(DATABASE_VERSION);
+        fReadOnly = fTmp;
+    }
+
+    printf("Opened RocksDB successfully\n");
+}
+
+CRocksTxDB::~CRocksTxDB()
+{
+    delete activeBatch;
+}
+
+void CRocksTxDB::Close()
+{
+    delete g_rocksdb;
+    g_rocksdb = pdb = nullptr;
+    delete activeBatch;
+    activeBatch = nullptr;
+}
+
+bool CRocksTxDB::TxnBegin()
+{
+    if (activeBatch)
+        return true;
+    activeBatch = new rocksdb::WriteBatch();
+    return true;
+}
+
+bool CRocksTxDB::TxnCommit()
+{
+    assert(activeBatch);
+    rocksdb::Status status = pdb->Write(rocksdb::WriteOptions(), activeBatch);
+    delete activeBatch;
+    activeBatch = nullptr;
+    if (!status.ok()) {
+        printf("ERROR: RocksDB batch commit failure: %s\n", status.ToString().c_str());
+        printf("ERROR: This may indicate disk full, corruption, or permissions issue.\n");
+        printf("ERROR: Chain state may be inconsistent - immediate investigation required!\n");
+        return false;
+    }
+    return true;
+}
+
+bool CRocksTxDB::TxnAbort()
+{
+    delete activeBatch;
+    activeBatch = nullptr;
+    return true;
+}
+
+namespace {
+
+// rocksdb::WriteBatch::Handler used to scan the active batch for a pending
+// write/delete on a given key, the same way the LevelDB backend does.
+class CRocksBatchScanner : public rocksdb::WriteBatch::Handler {
+public:
+    std::string needle;
+    bool* deleted = nullptr;
+    std::string* foundValue = nullptr;
+    bool foundEntry = false;
+
+    CRocksBatchScanner() = default;
+
+    void Put(const rocksdb::Slice& key, const rocksdb::Slice& value) override {
+        if (key.ToString() == needle) {
+            foundEntry = true;
+            *deleted = false;
+            *foundValue = value.ToString();
+        }
+    }
+
+    void Delete(const rocksdb::Slice& key) override {
+        if (key.ToString() == needle) {
+            foundEntry = true;
+            *deleted = true;
+        }
+    }
+};
+
+class CRocksDBIterator final : public CTxDBIteratorBase {
+public:
+    explicit CRocksDBIterator(rocksdb::Iterator* pit) : pit(pit) {}
+    ~CRocksDBIterator() override { delete pit; }
+
+    void Seek(const std::string& key) override { pit->Seek(key); }
+    bool Valid() const override { return pit->Valid(); }
+    void Next() override { pit->Next(); }
+    std::string KeyStr() const override   { return pit->key().ToString(); }
+    std::string ValueStr() const override { return pit->value().ToString(); }
+
+private:
+    rocksdb::Iterator* pit;
+};
+
+} // anonymous namespace
+
+bool CRocksTxDB::ScanBatch(const std::string& key, std::string* value, bool* deleted) const
+{
+    assert(activeBatch);
+    *deleted = false;
+    CRocksBatchScanner scanner;
+    scanner.needle = key;
+    scanner.deleted = deleted;
+    scanner.foundValue = value;
+    rocksdb::Status status = activeBatch->Iterate(&scanner);
+    if (!status.ok()) {
+        throw runtime_error(status.ToString());
+    }
+    return scanner.foundEntry;
+}
+
+bool CRocksTxDB::ReadRaw(const std::string& key, std::string& value) const
+{
+    bool readFromDb = true;
+    if (activeBatch) {
+        bool deleted = false;
+        readFromDb = ScanBatch(key, &value, &deleted) == false;
+        if (deleted)
+            return false;
+    }
+    if (readFromDb) {
+        rocksdb::Status status = pdb->Get(rocksdb::ReadOptions(), key, &value);
+        if (!status.ok()) {
+            if (status.IsNotFound())
+                return false;
+            printf("RocksDB read failure: %s\n", status.ToString().c_str());
+            return false;
+        }
+    }
+    return true;
+}
+
+bool CRocksTxDB::WriteRaw(const std::string& key, const std::string& value)
+{
+    if (activeBatch) {
+        activeBatch->Put(key, value);
+        return true;
+    }
+    rocksdb::Status status = pdb->Put(rocksdb::WriteOptions(), key, value);
+    if (!status.ok()) {
+        printf("RocksDB write failure: %s\n", status.ToString().c_str());
+        return false;
+    }
+    return true;
+}
+
+bool CRocksTxDB::EraseRaw(const std::string& key)
+{
+    if (!pdb)
+        return false;
+    if (activeBatch) {
+        activeBatch->Delete(key);
+        return true;
+    }
+    rocksdb::Status status = pdb->Delete(rocksdb::WriteOptions(), key);
+    return (status.ok() || status.IsNotFound());
+}
+
+bool CRocksTxDB::ExistsRaw(const std::string& key) const
+{
+    std::string unused;
+
+    if (activeBatch) {
+        bool deleted = false;
+        if (ScanBatch(key, &unused, &deleted) && !deleted)
+            return true;
+    }
+
+    rocksdb::Status status = pdb->Get(rocksdb::ReadOptions(), key, &unused);
+    return status.IsNotFound() == false;
+}
+
+std::unique_ptr<CTxDBIteratorBase> CRocksTxDB::NewIterator() const
+{
+    return std::unique_ptr<CTxDBIteratorBase>(
+        new CRocksDBIterator(pdb->NewIterator(rocksdb::ReadOptions())));
+}
+
+// ─── LoadBlockIndex ─────────────────────────────────────────────────────────
+// Mirrors CTxDB::LoadBlockIndex with rocksdb:: substitutions. The dbformat
+// upgrade path is preserved verbatim because a freshly-imported RocksDB may
+// have been migrated from a v1 LevelDB and still need the chain-trust pass.
+//
+// This duplication is acknowledged debt — CTxDBBase will absorb LoadBlockIndex
+// into the base class in a later phase once the iterator/batch abstractions
+// have proven stable across both backends.
+// ────────────────────────────────────────────────────────────────────────────
+static CBlockIndex *InsertBlockIndexRocks(uint256 hash)
+{
+    if (hash == 0)
+        return nullptr;
+
+    auto mi = mapBlockIndex.find(hash);
+    if (mi != mapBlockIndex.end())
+        return mi->second;
+
+    CBlockIndex* pindexNew = new CBlockIndex();
+    if (!pindexNew)
+        throw runtime_error("LoadBlockIndex(): new CBlockIndex failed");
+    mi = mapBlockIndex.insert(make_pair(hash, pindexNew)).first;
+    pindexNew->phashBlock = &mi->first;
+
+    return pindexNew;
+}
+
+bool CRocksTxDB::LoadBlockIndex()
+{
+    if (mapBlockIndex.size() > 0) {
+        return true;
+    }
+
+    int nDbFormat = 1;
+    ReadDbFormat(nDbFormat);
+    CDiskBlockIndex::fSerializeChainTrust = (nDbFormat >= 2);
+
+    if (CDiskBlockIndex::fSerializeChainTrust)
+        printf("LoadBlockIndex(): RocksDB format v%d - nChainTrust persisted\n", nDbFormat);
+    else
+        printf("LoadBlockIndex(): RocksDB format v%d - will recalculate nChainTrust\n", nDbFormat);
+
+    int64_t nPhaseStart = GetTimeMillis();
+    int64_t nTotalStart = nPhaseStart;
+    rocksdb::Iterator* iterator = pdb->NewIterator(rocksdb::ReadOptions());
+    CDataStream ssStartKey(SER_DISK, CLIENT_VERSION);
+    ssStartKey << make_pair(string("blockindex"), uint256(0));
+    iterator->Seek(ssStartKey.str());
+    int nBlocksLoaded = 0;
+    while (iterator->Valid())
+    {
+        if (++nBlocksLoaded % 100000 == 0)
+        {
+            std::string strMsg = strprintf(_("Loading block index... (%d blocks)"), nBlocksLoaded);
+            uiInterface.InitMessage(strMsg);
+        }
+
+        CDataStream ssKey(SER_DISK, CLIENT_VERSION);
+        ssKey.write(iterator->key().data(), iterator->key().size());
+        CDataStream ssValue(SER_DISK, CLIENT_VERSION);
+        ssValue.write(iterator->value().data(), iterator->value().size());
+        string strType;
+        ssKey >> strType;
+        if (fRequestShutdown || strType != "blockindex")
+            break;
+        CDiskBlockIndex diskindex;
+        ssValue >> diskindex;
+
+        uint256 blockHash = diskindex.GetBlockHash();
+
+        CBlockIndex* pindexNew    = InsertBlockIndexRocks(blockHash);
+        pindexNew->pprev          = InsertBlockIndexRocks(diskindex.hashPrev);
+        pindexNew->pnext          = InsertBlockIndexRocks(diskindex.hashNext);
+        pindexNew->nFile          = diskindex.nFile;
+        pindexNew->nBlockPos      = diskindex.nBlockPos;
+        pindexNew->nHeight        = diskindex.nHeight;
+        pindexNew->nMint          = diskindex.nMint;
+        pindexNew->nMoneySupply   = diskindex.nMoneySupply;
+        pindexNew->nFlags         = diskindex.nFlags;
+        pindexNew->nStakeModifier = diskindex.nStakeModifier;
+        pindexNew->prevoutStake   = diskindex.prevoutStake;
+        pindexNew->nStakeTime     = diskindex.nStakeTime;
+        pindexNew->hashProofOfStake = diskindex.hashProofOfStake;
+        pindexNew->nVersion       = diskindex.nVersion;
+        pindexNew->hashMerkleRoot = diskindex.hashMerkleRoot;
+        pindexNew->nTime          = diskindex.nTime;
+        pindexNew->nBits          = diskindex.nBits;
+        pindexNew->nNonce         = diskindex.nNonce;
+        pindexNew->nChainTrust    = diskindex.nChainTrust;
+
+        if (pindexGenesisBlock == nullptr && blockHash == (!fTestNet ? hashGenesisBlockOfficial : hashGenesisBlockTestNet))
+            pindexGenesisBlock = pindexNew;
+
+        if (!pindexNew->CheckIndex()) {
+            delete iterator;
+            return error("LoadBlockIndex(): CheckIndex failed at %d", pindexNew->nHeight);
+        }
+
+        iterator->Next();
+    }
+    delete iterator;
+    printf("STARTUP-PERF: block_index_deserialize %" PRId64 "ms blocks=%d\n",
+           GetTimeMillis() - nPhaseStart, nBlocksLoaded);
+
+    if (fRequestShutdown)
+        return true;
+
+    nPhaseStart = GetTimeMillis();
+    bool fNeedChainTrustRecalc = !CDiskBlockIndex::fSerializeChainTrust;
+
+    if (fNeedChainTrustRecalc)
+    {
+        uiInterface.InitMessage(_("Calculating chain trust (one-time upgrade)..."));
+
+        vector<pair<int, CBlockIndex*> > vSortedByHeight;
+        vSortedByHeight.reserve(mapBlockIndex.size());
+        for (const auto& item : mapBlockIndex)
+            vSortedByHeight.push_back(make_pair(item.second->nHeight, item.second));
+        sort(vSortedByHeight.begin(), vSortedByHeight.end());
+
+        int nLastCheckpointHeight = Checkpoints::GetTotalBlocksEstimate();
+        int nProgressInterval = std::max((int)vSortedByHeight.size() / 20, 1);
+        int nCount = 0;
+
+        for (const auto& item : vSortedByHeight)
+        {
+            CBlockIndex* pindex = item.second;
+            pindex->nChainTrust = (pindex->pprev ? pindex->pprev->nChainTrust : 0)
+                                + pindex->GetBlockTrust();
+
+            if (pindex->nHeight >= nLastCheckpointHeight)
+            {
+                pindex->nStakeModifierChecksum = GetStakeModifierChecksum(pindex);
+                if (!CheckStakeModifierCheckpoints(pindex->nHeight, pindex->nStakeModifierChecksum))
+                    return error("LoadBlockIndex(): Failed stake modifier checkpoint h=%d, mod=0x%016"PRIx64,
+                                 pindex->nHeight, pindex->nStakeModifier);
+            }
+
+            if (++nCount % nProgressInterval == 0)
+            {
+                std::string strMsg = strprintf(_("Calculating chain trust... (%d%%)"),
+                                               nCount * 100 / vSortedByHeight.size());
+                uiInterface.InitMessage(strMsg);
+            }
+        }
+
+        printf("LoadBlockIndex(): upgrading RocksDB to format v3...\n");
+        uiInterface.InitMessage(_("Upgrading block index..."));
+        CDiskBlockIndex::fSerializeChainTrust = true;
+
+        rocksdb::WriteBatch batch;
+        nCount = 0;
+        for (const auto& item : vSortedByHeight)
+        {
+            CBlockIndex* pindex = item.second;
+            CDiskBlockIndex diskindex(pindex);
+
+            CDataStream ssKey(SER_DISK, CLIENT_VERSION);
+            ssKey << make_pair(string("blockindex"), *pindex->phashBlock);
+            CDataStream ssValue(SER_DISK, CLIENT_VERSION);
+            ssValue << diskindex;
+            batch.Put(ssKey.str(), ssValue.str());
+
+            if (++nCount % 100000 == 0)
+            {
+                pdb->Write(rocksdb::WriteOptions(), &batch);
+                batch.Clear();
+                printf("LoadBlockIndex(): upgraded %d / %d entries\n",
+                       nCount, (int)vSortedByHeight.size());
+            }
+        }
+        CDataStream ssFmtKey(SER_DISK, CLIENT_VERSION);
+        ssFmtKey << string("dbformat");
+        CDataStream ssFmtValue(SER_DISK, CLIENT_VERSION);
+        ssFmtValue << (int)3;
+        batch.Put(ssFmtKey.str(), ssFmtValue.str());
+
+        rocksdb::Status status = pdb->Write(rocksdb::WriteOptions(), &batch);
+        if (!status.ok())
+            return error("LoadBlockIndex(): failed to write upgraded block index: %s",
+                         status.ToString().c_str());
+
+        printf("LoadBlockIndex(): RocksDB upgraded to format v3 (%d entries)\n", nCount);
+    }
+    else
+    {
+        int nLastCheckpointHeight = Checkpoints::GetTotalBlocksEstimate();
+        bool fNeedModifierCheck = false;
+        for (const auto& item : mapBlockIndex)
+        {
+            if (item.second->nHeight >= nLastCheckpointHeight)
+            {
+                fNeedModifierCheck = true;
+                break;
+            }
+        }
+
+        if (fNeedModifierCheck)
+        {
+            vector<pair<int, CBlockIndex*> > vAboveCheckpoint;
+            for (const auto& item : mapBlockIndex)
+                if (item.second->nHeight >= nLastCheckpointHeight)
+                    vAboveCheckpoint.push_back(make_pair(item.second->nHeight, item.second));
+            sort(vAboveCheckpoint.begin(), vAboveCheckpoint.end());
+
+            for (const auto& item : vAboveCheckpoint)
+            {
+                CBlockIndex* pindex = item.second;
+                pindex->nStakeModifierChecksum = GetStakeModifierChecksum(pindex);
+                if (!CheckStakeModifierCheckpoints(pindex->nHeight, pindex->nStakeModifierChecksum))
+                    return error("LoadBlockIndex(): Failed stake modifier checkpoint h=%d, mod=0x%016"PRIx64,
+                                 pindex->nHeight, pindex->nStakeModifier);
+            }
+        }
+    }
+
+    printf("STARTUP-PERF: chain_trust_and_modifiers %" PRId64 "ms\n",
+           GetTimeMillis() - nPhaseStart);
+
+    if (nDbFormat < 3)
+    {
+        WriteDbFormat(3);
+        printf("LoadBlockIndex(): bumped RocksDB dbformat to v3\n");
+    }
+
+    nPhaseStart = GetTimeMillis();
+    if (!ReadHashBestChain(hashBestChain))
+    {
+        if (pindexGenesisBlock == nullptr)
+            return true;
+        return error("LoadBlockIndex(): hashBestChain not loaded");
+    }
+    if (!mapBlockIndex.count(hashBestChain))
+        return error("LoadBlockIndex(): hashBestChain not found in the block index");
+    pindexBest = mapBlockIndex[hashBestChain];
+    nBestHeight = pindexBest->nHeight;
+    nBestChainTrust = pindexBest->nChainTrust;
+
+    printf("STARTUP-PERF: best_chain %" PRId64 "ms\n", GetTimeMillis() - nPhaseStart);
+
+    nPhaseStart = GetTimeMillis();
+    {
+        int nStakeSeenDepth = 500;
+        CBlockIndex* pindex = pindexBest;
+        int nLoaded = 0;
+        while (pindex && nLoaded < nStakeSeenDepth)
+        {
+            if (pindex->IsProofOfStake())
+                setStakeSeen.insert(make_pair(pindex->prevoutStake, pindex->nStakeTime));
+            pindex = pindex->pprev;
+            nLoaded++;
+        }
+        printf("LoadBlockIndex(): populated setStakeSeen with %d entries (last %d blocks)\n",
+               (int)setStakeSeen.size(), nLoaded);
+    }
+    printf("STARTUP-PERF: stake_seen %" PRId64 "ms\n", GetTimeMillis() - nPhaseStart);
+
+    printf("LoadBlockIndex(): hashBestChain=%s height=%d trust=%s date=%s\n",
+        hashBestChain.ToString().substr(0,20).c_str(), nBestHeight,
+        CBigNum(nBestChainTrust).ToString().c_str(),
+        DateTimeStrFormat("%x %H:%M:%S", pindexBest->GetBlockTime()).c_str());
+
+    {
+        CBlockIndex* pindexBetter = nullptr;
+        for (const auto& item : mapBlockIndex)
+        {
+            CBlockIndex* pindex = item.second;
+            if (pindex == pindexBest)
+                continue;
+            if (pindex->nChainTrust > nBestChainTrust)
+            {
+                pindexBetter = pindex;
+                break;
+            }
+            if (pindex->nChainTrust == nBestChainTrust &&
+                pindex->GetBlockHash() < pindexBest->GetBlockHash())
+            {
+                if (!pindexBetter || pindex->GetBlockHash() < pindexBetter->GetBlockHash())
+                    pindexBetter = pindex;
+            }
+        }
+        if (pindexBetter)
+        {
+            printf("LoadBlockIndex(): better chain tip %s at %d (trust %s vs %s)\n",
+                pindexBetter->GetBlockHash().ToString().substr(0,20).c_str(),
+                pindexBetter->nHeight,
+                CBigNum(pindexBetter->nChainTrust).ToString().c_str(),
+                CBigNum(nBestChainTrust).ToString().c_str());
+            CBlock block;
+            if (block.ReadFromDisk(pindexBetter))
+            {
+                CRocksTxDB txdb2;
+                if (block.SetBestChain(txdb2, pindexBetter))
+                {
+                    hashBestChain = pindexBetter->GetBlockHash();
+                    pindexBest = pindexBetter;
+                    nBestHeight = pindexBetter->nHeight;
+                    nBestChainTrust = pindexBetter->nChainTrust;
+                    printf("LoadBlockIndex(): switched to better chain tip\n");
+                }
+            }
+        }
+    }
+
+    if (!ReadSyncCheckpoint(Checkpoints::hashSyncCheckpoint))
+        printf("LoadBlockIndex(): no sync checkpoint in DB, using default\n");
+    else
+        printf("LoadBlockIndex(): synchronized checkpoint %s\n",
+               Checkpoints::hashSyncCheckpoint.ToString().c_str());
+    if (!mapBlockIndex.count(Checkpoints::hashSyncCheckpoint))
+    {
+        printf("LoadBlockIndex(): sync checkpoint not in index, resetting to genesis\n");
+        Checkpoints::hashSyncCheckpoint = (!fTestNet ? hashGenesisBlockOfficial
+                                                    : hashGenesisBlockTestNet);
+    }
+
+    CBigNum bnBestInvalidTrust;
+    ReadBestInvalidTrust(bnBestInvalidTrust);
+    nBestInvalidTrust = bnBestInvalidTrust.getuint256();
+
+    nPhaseStart = GetTimeMillis();
+    int nCheckLevel = GetArg("-checklevel", 1);
+    int nCheckDepth = GetArg("-checkblocks", 50);
+    if (nCheckDepth == 0)
+        nCheckDepth = 1000000000;
+    if (nCheckDepth > nBestHeight)
+        nCheckDepth = nBestHeight;
+    printf("Verifying last %i blocks at level %i\n", nCheckDepth, nCheckLevel);
+    CBlockIndex* pindexFork = nullptr;
+    map<pair<unsigned int, unsigned int>, CBlockIndex*> mapBlockPos;
+    for (CBlockIndex* pindex = pindexBest; pindex && pindex->pprev; pindex = pindex->pprev)
+    {
+        if (fRequestShutdown || pindex->nHeight < nBestHeight - nCheckDepth)
+            break;
+        CBlock block;
+        if (!block.ReadFromDisk(pindex))
+            return error("LoadBlockIndex(): block.ReadFromDisk failed");
+        if (nCheckLevel > 0 && !block.CheckBlock(true, true, (nCheckLevel > 6)))
+        {
+            printf("LoadBlockIndex(): bad block at %d, hash=%s\n",
+                   pindex->nHeight, pindex->GetBlockHash().ToString().c_str());
+            pindexFork = pindex->pprev;
+        }
+        if (nCheckLevel > 1)
+        {
+            pair<unsigned int, unsigned int> pos = make_pair(pindex->nFile, pindex->nBlockPos);
+            mapBlockPos[pos] = pindex;
+            for (const CTransaction &tx : block.vtx)
+            {
+                uint256 hashTx = tx.GetHash();
+                CTxIndex txindex;
+                if (ReadTxIndex(hashTx, txindex))
+                {
+                    if (nCheckLevel > 2 || pindex->nFile != txindex.pos.nFile
+                        || pindex->nBlockPos != txindex.pos.nBlockPos)
+                    {
+                        CTransaction txFound;
+                        if (!txFound.ReadFromDisk(txindex.pos))
+                        {
+                            printf("LoadBlockIndex(): cannot read mislocated transaction %s\n",
+                                   hashTx.ToString().c_str());
+                            pindexFork = pindex->pprev;
+                        }
+                        else if (txFound.GetHash() != hashTx)
+                        {
+                            printf("LoadBlockIndex(): invalid tx position for %s\n",
+                                   hashTx.ToString().c_str());
+                            pindexFork = pindex->pprev;
+                        }
+                    }
+                    if (nCheckLevel > 3 && !tx.IsCoinBase())
+                    {
+                        for (const CTxIn &txin : tx.vin)
+                        {
+                            if (HaveUtxo(txin.prevout.hash, txin.prevout.n))
+                            {
+                                printf("LoadBlockIndex(): spent input still in UTXO set: %s:%i in %s\n",
+                                       txin.prevout.hash.ToString().c_str(), txin.prevout.n,
+                                       hashTx.ToString().c_str());
+                                pindexFork = pindex->pprev;
+                            }
+                        }
+                    }
+                }
+            }
+        }
+    }
+    if (pindexFork && !fRequestShutdown)
+    {
+        printf("LoadBlockIndex(): moving best chain pointer back to block %d\n",
+               pindexFork->nHeight);
+        CBlock block;
+        if (!block.ReadFromDisk(pindexFork))
+            return error("LoadBlockIndex(): block.ReadFromDisk failed");
+        CRocksTxDB txdb;
+        block.SetBestChain(txdb, pindexFork);
+    }
+    printf("STARTUP-PERF: verify_blocks %" PRId64 "ms depth=%d level=%d\n",
+           GetTimeMillis() - nPhaseStart, nCheckDepth, nCheckLevel);
+    printf("STARTUP-PERF: load_block_index_total %" PRId64 "ms\n",
+           GetTimeMillis() - nTotalStart);
+
+    return true;
+}
+
+#endif // BUILD_ROCKSDB

src/txdb-rocksdb.h

@@ -0,0 +1,57 @@
+// Copyright (c) 2026 The Triangles developers.
+// Distributed under the MIT/X11 software license, see the accompanying
+// file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#ifndef TRIANGLES_TXDB_ROCKSDB_H
+#define TRIANGLES_TXDB_ROCKSDB_H
+
+#ifdef BUILD_ROCKSDB
+
+#include "txdb-base.h"
+
+#include <rocksdb/db.h>
+#include <rocksdb/options.h>
+#include <rocksdb/write_batch.h>
+
+// RocksDB backend for the chain database.
+//
+// Mirrors CTxDB (LevelDB) for byte-level compatibility. CTxDBBase owns all
+// key serialization, so keys produced by this backend are bit-identical to
+// the LevelDB backend. That property is what lets the M1.4 dual-backend
+// parity harness verify equivalence.
+//
+// Data lives under <datadir>/rocksdb/, separate from <datadir>/txleveldb/,
+// so both backends can coexist for migration and side-by-side testing.
+class CRocksTxDB final : public CTxDBBase
+{
+public:
+    CRocksTxDB(const char* pszMode = "r+");
+    ~CRocksTxDB() override;
+
+    void Close() override;
+
+    bool TxnBegin() override;
+    bool TxnCommit() override;
+    bool TxnAbort() override;
+
+    bool LoadBlockIndex() override;
+
+protected:
+    bool ReadRaw(const std::string& key, std::string& value) const override;
+    bool WriteRaw(const std::string& key, const std::string& value) override;
+    bool EraseRaw(const std::string& key) override;
+    bool ExistsRaw(const std::string& key) const override;
+    std::unique_ptr<CTxDBIteratorBase> NewIterator() const override;
+
+private:
+    rocksdb::DB* pdb;                   // Points to the global instance.
+    rocksdb::WriteBatch* activeBatch;   // When non-NULL, writes/deletes go here.
+    rocksdb::Options options;
+    int nVersion;
+
+    bool ScanBatch(const std::string& key, std::string* value, bool* deleted) const;
+};
+
+#endif // BUILD_ROCKSDB
+
+#endif // TRIANGLES_TXDB_ROCKSDB_H