rocksdb: apply T010 review fixes (H1/H2/H3/M4) + CF routing disabled

H1: init.cpp now detects crashed migrations (MIGRATION_INCOMPLETE marker)
    and retries instead of opening a partial RocksDB. Refuses to start if
    the marker persists after migration attempt.
H2: LevelDB ExistsRaw now returns false for keys deleted in the active
    batch, matching ReadRaw and the RocksDB backend. Fixes latent
    cross-backend consensus split in intra-batch spend checks.
H3: All RocksDB close paths now go through close_rocksdb() which
    destroys CF handles before deleting the DB. Fixes RocksDB assertion
    / UB on shutdown and version-reset.
M4: Migration marker write is now flushed + verified (refuses to start
    migration if marker can't be written).

CF routing permanently disabled: GetCF() always returns nullptr (default
column family). The read path (NewIterator, LoadBlockIndex) only iterates
the default CF, so writes routed to per-prefix CFs were invisible to scans.
This is why -chaindb=rocksdb compiled clean but was never runtime-valid.
Existing CF-enabled DBs still open (handles retained for cleanup) but no
routing occurs. CF-aware iteration is a future follow-up.

txdb-factory: RocksDB is now the default backend (was still leveldb).
Tests updated for RocksDB-as-default expectations.

From Claude's ROCKSDB-T010-REVIEW-2026-07-01 audit on E:\repos\triangles.

src/chaindb_migrate.cpp

@@ -109,6 +109,13 @@ bool MaybeMigrateLevelDbToRocksDb(bool fForce, std::string& strError)
         {
             std::ofstream marker(markerPath);
             marker << "RocksDB migration in progress. Safe to delete this directory and retry.\n";
+            marker.flush();
+            if (!marker.good()) {
+                // Without the marker a crashed migration would be
+                // indistinguishable from a complete one — refuse to start.
+                strError = "could not write migration marker " + markerPath.string();
+                return false;
+            }
         }
 
         CTxDB source("r");

src/init.cpp

@@ -1279,20 +1279,37 @@ bool AppInit2()
     {
         bool fExplicit = GetBoolArg("-migratechaindb", false) ||
                          GetBoolArg("-migratechaindbforce", false);
+        // A rocksdb/ directory containing the MIGRATION_INCOMPLETE marker is a
+        // crashed previous migration, NOT a usable chain DB — treat it the same
+        // as "no rocksdb yet" so the migration is retried instead of silently
+        // opening a truncated database.
+        bool fCrashedMigration = fs::exists(GetDataDir() / "rocksdb" / "MIGRATION_INCOMPLETE");
         bool fAuto = IsRocksDbChainBackend() &&
                      fs::exists(GetDataDir() / "txleveldb") &&
-                     !fs::exists(GetDataDir() / "rocksdb");
+                     (!fs::exists(GetDataDir() / "rocksdb") || fCrashedMigration);
         if (fExplicit || fAuto)
         {
             uiInterface.InitMessage(_("Migrating chain database to RocksDB..."));
             if (fAuto && !fExplicit)
-                printf("ChainDB: RocksDB backend active with a legacy LevelDB present; "
-                       "migrating automatically.\n");
+                printf("ChainDB: RocksDB backend active with a legacy LevelDB present%s; "
+                       "migrating automatically.\n",
+                       fCrashedMigration ? " and a previous migration was interrupted" : "");
             std::string strMigrateError;
             bool fForce = GetBoolArg("-migratechaindbforce", false);
             if (!MaybeMigrateLevelDbToRocksDb(fForce, strMigrateError))
                 return InitError(strprintf(_("Chain DB migration failed: %s"), strMigrateError.c_str()));
         }
+        // Last line of defense: never open a RocksDB that still carries the
+        // incomplete-migration marker (e.g. the LevelDB source was deleted so
+        // the migration cannot be retried). Opening it would silently run on a
+        // partial chain state.
+        if (IsRocksDbChainBackend() &&
+            fs::exists(GetDataDir() / "rocksdb" / "MIGRATION_INCOMPLETE"))
+        {
+            return InitError(_("The RocksDB chain database is left over from an interrupted "
+                               "migration and is incomplete. Delete the 'rocksdb' directory in the "
+                               "data directory and restart (it will be rebuilt by migration or resync)."));
+        }
     }
 
     // ********************************************************* Step 7: load blockchain

src/test/chaindb_runtime_tests.cpp

@@ -141,16 +141,19 @@ BOOST_AUTO_TEST_SUITE(chaindb_backend_selection)
 
 BOOST_AUTO_TEST_CASE(is_rocksdb_backend_flag_default_off)
 {
-    // Default test build doesn't set -chaindb, so backend should NOT be rocksdb.
+    // The default test build doesn't set the -chaindb flag at all. (The
+    // resolved default backend is RocksDB; this case only asserts the raw flag
+    // is absent — see get_chain_data_dir_default_is_rocksdb for the default.)
     BOOST_CHECK_EQUAL(GetBoolArg("-chaindb", false), false);
 }
 
-BOOST_AUTO_TEST_CASE(get_chain_data_dir_default_is_txleveldb)
+BOOST_AUTO_TEST_CASE(get_chain_data_dir_default_is_rocksdb)
 {
-    // No -chaindb flag set → GetChainDataDir() must return txleveldb path.
+    // No -chaindb flag set → RocksDB is the default backend, so
+    // GetChainDataDir() must return the rocksdb path.
     mapArgs.erase("-chaindb");
-    BOOST_CHECK_EQUAL(IsRocksDbChainBackend(), false);
-    BOOST_CHECK_EQUAL(GetChainDataDir().filename().string(), "txleveldb");
+    BOOST_CHECK_EQUAL(IsRocksDbChainBackend(), true);
+    BOOST_CHECK_EQUAL(GetChainDataDir().filename().string(), "rocksdb");
 }
 
 BOOST_AUTO_TEST_CASE(get_chain_data_dir_rocksdb_when_flag_set)
@@ -451,12 +454,13 @@ BOOST_AUTO_TEST_CASE(wipe_removes_rocksdb_dir_when_flagged)
     mapArgs.erase("-chaindb");
 }
 
-BOOST_AUTO_TEST_CASE(wipe_removes_txleveldb_dir_by_default)
+BOOST_AUTO_TEST_CASE(wipe_removes_txleveldb_dir_when_leveldb_selected)
 {
-    // No explicit write needed — MakeChainDB("cr+") opens the LevelDB
-    // handle which creates the txleveldb/ directory on disk. The wipe test
-    // just verifies that directory exists pre-wipe and is gone post-wipe.
-    mapArgs.erase("-chaindb");
+    // With -chaindb=leveldb, MakeChainDB("cr+") opens the LevelDB handle which
+    // creates the txleveldb/ directory on disk. The wipe test just verifies
+    // that directory exists pre-wipe and is gone post-wipe. (RocksDB is the
+    // default now, so LevelDB must be requested explicitly.)
+    mapArgs["-chaindb"] = "leveldb";
     {
         auto base = MakeChainDB("cr+");
         BOOST_REQUIRE(base != nullptr);
@@ -467,6 +471,7 @@ BOOST_AUTO_TEST_CASE(wipe_removes_txleveldb_dir_by_default)
 
     WipeChainDataDir();
     BOOST_CHECK(!fs::exists(dir));
+    mapArgs.erase("-chaindb");
 }
 
 BOOST_AUTO_TEST_SUITE_END()

src/txdb-factory.cpp

@@ -23,7 +23,10 @@ enum class ChainDbKind { LevelDB, RocksDB };
 
 ChainDbKind ResolveChainDbKind()
 {
-    std::string s = GetArg("-chaindb", std::string("leveldb"));
+    // RocksDB is the default backend. LevelDB remains selectable with
+    // -chaindb=leveldb and is retained as the migration source and fallback;
+    // its removal is deferred to a later phase after live-chain validation.
+    std::string s = GetArg("-chaindb", std::string("rocksdb"));
     for (auto& c : s) c = std::tolower(static_cast<unsigned char>(c));
 
     if (s == "leveldb")

src/txdb-leveldb.cpp

@@ -274,8 +274,15 @@ bool CTxDB::ExistsRaw(const std::string& key) const
 
     if (activeBatch) {
         bool deleted = false;
-        if (ScanBatch(key, &unused, &deleted) && !deleted)
-            return true;
+        if (ScanBatch(key, &unused, &deleted)) {
+            // Mirror ReadRaw() and the RocksDB backend: an entry that is
+            // deleted in the active batch does NOT exist, even if an older
+            // copy is still on disk. Falling through to the disk lookup here
+            // (the old behavior) made Exists() disagree with Read() and with
+            // CRocksTxDB::ExistsRaw — a latent cross-backend consensus split
+            // for intra-batch spend checks (see ROCKSDB-T010-REVIEW, H2).
+            return !deleted;
+        }
     }
 
     leveldb::Status status = pdb->Get(leveldb::ReadOptions(), key, &unused);

src/txdb-rocksdb.cpp

@@ -31,8 +31,26 @@ namespace fs = std::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::ColumnFamilyHandle* g_cf_handles[5] = {};  // indexed by CF_ enum
 static bool g_cf_enabled = false;
+// Handles returned by the column-family Open. The RocksDB API contract
+// requires DestroyColumnFamilyHandle() on every handle BEFORE deleting the
+// DB (asserts in debug builds, UB/leak in release). Kept here so
+// close_rocksdb() can honor that.
+static std::vector<rocksdb::ColumnFamilyHandle*> g_cf_handles;
+
+// Single close path: destroy CF handles first, then the DB.
+static void close_rocksdb()
+{
+    if (g_rocksdb) {
+        for (rocksdb::ColumnFamilyHandle* h : g_cf_handles) {
+            if (h)
+                g_rocksdb->DestroyColumnFamilyHandle(h);
+        }
+    }
+    g_cf_handles.clear();
+    delete g_rocksdb;
+    g_rocksdb = nullptr;
+}
 
 // Non-batched writes bypass WAL fsync. The TxnCommit path handles durability;
 // crash recovery replays from block files anyway. Default WriteOptions may
@@ -130,27 +148,8 @@ static rocksdb::Options GetRocksOptions()
     return opts;
 }
 
-// ─── Column family names ───────────────────────────────────────────────────
-static const std::string CF_NAMES[] = {
-    rocksdb::kDefaultColumnFamilyName,  // CF_DEFAULT (index 0)
-    "blockindex",                       // CF_BLOCKINDEX (index 1)
-    "txindex",                          // CF_TXINDEX (index 2)
-    "utxo",                             // CF_UTXO (index 3)
-    "addrindex",                        // CF_ADDRINDEX (index 4)
-};
-static constexpr int CF_COUNT = 5;
-
-// Prefix-to-CF routing table. Keys starting with these prefixes go to
-// the indicated CF index. Everything else stays in CF_DEFAULT (metadata).
-struct CfPrefixEntry { const char* prefix; int len; int cf_index; };
-static CfPrefixEntry prefixMap_[] = {
-    {"b",     1, 1},  // CF_BLOCKINDEX
-    {"t",     1, 2},  // CF_TXINDEX
-    {"u",     1, 3},  // CF_UTXO
-    {"addrbal",  7, 4},  // CF_ADDRINDEX
-    {"addrutxo", 8, 4},  // CF_ADDRINDEX
-    {"addrtxid", 8, 4},  // CF_ADDRINDEX
-};
+// Column-family partitioning is disabled (see CRocksTxDB::GetCF). All keys live
+// in the default column family, mirroring the single-keyspace LevelDB backend.
 
 static void open_rocksdb(rocksdb::Options& options, bool fRemoveOld = false)
 {
@@ -163,58 +162,54 @@ static void open_rocksdb(rocksdb::Options& options, bool fRemoveOld = false)
     fs::create_directory(directory);
     printf("Opening RocksDB in %s\n", directory.string().c_str());
 
-    // Try opening with column families. First, list existing CFs.
+    // Column-family partitioning is disabled (see CRocksTxDB::GetCF): all data
+    // lives in the default CF so writes, point reads, and full-keyspace
+    // iteration stay mutually consistent. New databases are therefore created
+    // single-CF.
+    //
+    // For openability we must still enumerate any column families that already
+    // exist on disk — RocksDB refuses to open a database unless every existing
+    // CF is named in the open call. Experimental pre-release databases may
+    // contain the old blockindex/txindex/utxo/addrindex CFs; we open them so
+    // the handle is valid, but never route to them. (Such a database would have
+    // chain data stranded in non-default CFs and should be re-migrated or
+    // reindexed; no production database is in that state.)
     std::vector<std::string> existingCFs;
     rocksdb::Options listOpts = options;
     listOpts.create_if_missing = false;
     rocksdb::DB::ListColumnFamilies(listOpts, directory.string(), &existingCFs);
 
-    bool needsCreate = (existingCFs.size() <= 1);  // Only "default" or empty
-
     std::vector<rocksdb::ColumnFamilyDescriptor> cfDescs;
-    for (int i = 0; i < CF_COUNT; i++) {
-        // Include this CF if it already exists OR if we're creating new
-        bool exists = false;
-        for (auto& name : existingCFs)
-            if (name == CF_NAMES[i]) { exists = true; break; }
-        if (exists || needsCreate) {
-            rocksdb::ColumnFamilyOptions cfOpts = options;
-            // Per-CF tuning:
-            if (i == 3) {  // UTXO: optimize for point lookups
-                cfOpts.OptimizeForPointLookup(static_cast<size_t>(GetArg("-dbcache", 2048)));
-            } else if (i == 4) {  // addrindex: optimize for scans
-                cfOpts.OptimizeLevelStyleCompaction(cfOpts.write_buffer_size);
-            }
-            cfDescs.push_back(rocksdb::ColumnFamilyDescriptor(CF_NAMES[i], cfOpts));
-        }
+    cfDescs.push_back(rocksdb::ColumnFamilyDescriptor(
+        rocksdb::kDefaultColumnFamilyName, rocksdb::ColumnFamilyOptions(options)));
+    for (const auto& name : existingCFs) {
+        if (name == rocksdb::kDefaultColumnFamilyName)
+            continue;  // default already added above
+        cfDescs.push_back(rocksdb::ColumnFamilyDescriptor(
+            name, rocksdb::ColumnFamilyOptions(options)));
     }
 
     std::vector<rocksdb::ColumnFamilyHandle*> handles;
     rocksdb::Status status = OpenRocksDBCF(options, directory.string(),
                                                 cfDescs, &handles, &g_rocksdb);
     if (!status.ok()) {
-        // Fallback: open without CFs (old-style single-CF database)
+        // Fallback: open without an explicit CF list (plain single-CF database).
         printf("RocksDB CF open failed (%s), falling back to single-CF\n", status.ToString().c_str());
         status = OpenRocksDB(options, directory.string(), &g_rocksdb);
         if (!status.ok()) {
             throw runtime_error(strprintf("open_rocksdb(): error opening database: %s",
                                           status.ToString().c_str()));
         }
+        g_cf_handles.clear(); // plain Open returns no handles to manage
         return;
     }
 
-    // Store handles in the global array (CF names map directly to indices)
-    for (size_t i = 0; i < handles.size() && i < CF_COUNT; i++) {
-        // Match handle to our index by name
-        std::string hname = handles[i]->GetName();
-        for (int j = 0; j < CF_COUNT; j++) {
-            if (hname == CF_NAMES[j]) {
-                g_cf_handles[j] = handles[i];
-                break;
-            }
-        }
-    }
-    g_cf_enabled = true;
+    // We only ever route to the default CF, so keep CF routing off. Any extra
+    // handles opened above for legacy-database compatibility are unused for
+    // routing but MUST be retained so close_rocksdb() can destroy them before
+    // the DB is deleted (RocksDB API requirement).
+    g_cf_handles = handles;
+    g_cf_enabled = false;
 }
 
 CRocksTxDB::CRocksTxDB(const char* pszMode)
@@ -245,8 +240,8 @@ CRocksTxDB::CRocksTxDB(const char* pszMode)
             printf("Required index version is %d, removing old RocksDB database\n",
                    DATABASE_VERSION);
 
-            delete g_rocksdb;
-            g_rocksdb = pdb = nullptr;
+            close_rocksdb();
+            pdb = nullptr;
             delete activeBatch;
             activeBatch = nullptr;
 
@@ -277,8 +272,8 @@ CRocksTxDB::~CRocksTxDB()
 
 void CRocksTxDB::Close()
 {
-    delete g_rocksdb;
-    g_rocksdb = pdb = nullptr;
+    close_rocksdb();
+    pdb = nullptr;
     delete activeBatch;
     activeBatch = nullptr;
 }
@@ -351,15 +346,30 @@ bool CRocksTxDB::ScanBatch(const std::string& key, std::string* value, bool* del
 }
 
 // ─── CF routing helper ──────────────────────────────────────────────────────
-rocksdb::ColumnFamilyHandle* CRocksTxDB::GetCF(const std::string& key) const
+// IMPORTANT: column-family partitioning is intentionally DISABLED.
+//
+// The earlier design split keys across per-prefix column families
+// (blockindex/txindex/utxo/addrindex) for independent compaction. But the read
+// path was never made CF-aware: both CRocksTxDB::NewIterator() and
+// CRocksTxDB::LoadBlockIndex() iterate the DEFAULT column family only. With
+// routing enabled, block-index records (and every other prefixed key) were
+// written into non-default CFs, so:
+//   - LoadBlockIndex() loaded ZERO blocks,
+//   - UTXO snapshot dumps and address-index range scans saw nothing, and
+//   - the migration verifier (CollectStats) counted a record mismatch.
+// This is why -chaindb=rocksdb "compiled clean but was never runtime-valid."
+//
+// Returning nullptr unconditionally routes ALL keys to the default CF, which
+// makes writes, point reads, Exists, Erase, and full-keyspace iteration
+// mutually consistent — and byte-identical to the single-keyspace LevelDB
+// backend, which the migration and dual-backend equivalence tests rely on.
+//
+// Re-introducing CFs is tracked as a follow-up and requires CF-aware iterators
+// in NewIterator()/LoadBlockIndex() (a multiplexed merge across CFs) before the
+// prefix router below can be re-enabled.
+rocksdb::ColumnFamilyHandle* CRocksTxDB::GetCF(const std::string& /*key*/) const
 {
-    if (!g_cf_enabled)
-        return nullptr;  // nullptr = default CF
-    for (auto& entry : prefixMap_) {
-        if ((int)key.size() >= entry.len && key.compare(0, entry.len, entry.prefix) == 0)
-            return g_cf_handles[entry.cf_index];
-    }
-    return nullptr;  // default CF for metadata keys
+    return nullptr;  // single keyspace: always the default column family
 }
 
 bool CRocksTxDB::ReadRaw(const std::string& key, std::string& value) const