chain: add isolated testnet genesis

6 files changed, 105 insertions, 30 deletions

diff --git a/README.md b/README.md
index 4843f5c..77227fa 100644
--- a/README.md
+++ b/README.md
@@ -355,7 +355,7 @@ Other options worth knowing:
 
 ```bash
 -datadir=PATH    # wallet and chain data elsewhere
--testnet         # isolated test network datadir, port 18433, and message magic
+-testnet         # isolated test network genesis, datadir, port 18433, and magic
 -port=N          # P2P listen port, default 8433; testnet default 18433
 -socks=HOST:PORT # SOCKS5 for outbound Nostr, .btf relay, and onion peer dials
 -tor[=HOST:PORT] # Tor mode; default local Tor SOCKS5 proxy is 127.0.0.1:9050
diff --git a/src/main.cpp b/src/main.cpp
index 6fd8c82..5d266ff 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -41,12 +41,30 @@ unsigned int nTransactionsUpdated = 0;
 map<COutPoint, CInPoint> mapNextTx;
 
 map<uint256, CBlockIndex*> mapBlockIndex;
-// Bitflash genesis -- mined under RandomX PoW on 2026-07-22
-// (nTime 1753142400, nBits 0x1f0fffff, RandomX key "Bitflash/RandomX/v1/...")
-// Bitflash 2026 stable relaunch genesis (2-min blocks, RandomX). Mined values.
-unsigned int GENESIS_NONCE = 3141;
-uint256 hashGenesisBlock("0x5bd7cb255d814e48cebcdfb72da4dc87b34bd774227f8ceb546c5640f4bdc169");
-uint256 hashGenesisMerkleRoot("0x1a45b4482532abb29b10e234d3f13132230525a339ecea91658ffa675a5b1325");
+// Bitflash mainnet genesis -- mined under RandomX PoW for the 2026 stable
+// relaunch. Testnet gets its own resettable genesis below so block indexes,
+// headers, and wallet scans cannot be accidentally mixed across networks.
+static const unsigned int MAINNET_GENESIS_TIME  = 1753315200; // 2026-07-24 00:00:00 UTC
+static const unsigned int MAINNET_GENESIS_NONCE = 3141;
+static const char* MAINNET_GENESIS_TIMESTAMP =
+    "Bitflash 24/Jul/2026 Fair launch: one CPU one vote, no premine";
+static const char* MAINNET_GENESIS_HASH =
+    "0x5bd7cb255d814e48cebcdfb72da4dc87b34bd774227f8ceb546c5640f4bdc169";
+static const char* MAINNET_GENESIS_MERKLE =
+    "0x1a45b4482532abb29b10e234d3f13132230525a339ecea91658ffa675a5b1325";
+
+static const unsigned int TESTNET_GENESIS_TIME  = 1787184000; // 2026-08-20 00:00:00 UTC
+static const unsigned int TESTNET_GENESIS_NONCE = 3199;
+static const char* TESTNET_GENESIS_TIMESTAMP =
+    "Bitflash testnet 20/Aug/2026: resettable public test chain";
+static const char* TESTNET_GENESIS_HASH =
+    "0xa9d11c6d697bcb7aea0653bc088b12dcf9f44e732df205162cf085fd9d9963eb";
+static const char* TESTNET_GENESIS_MERKLE =
+    "0x510b293105e3ff85b8d4c3920e357f85d1a86bf199eb4e7d11f04f380030ec5c";
+
+unsigned int GENESIS_NONCE = MAINNET_GENESIS_NONCE;
+uint256 hashGenesisBlock(MAINNET_GENESIS_HASH);
+uint256 hashGenesisMerkleRoot(MAINNET_GENESIS_MERKLE);
 CBlockIndex* pindexGenesisBlock = NULL;
 int nBestHeight = -1;
 uint256 hashBestChain = 0;
@@ -117,6 +135,63 @@ static std::atomic<uint64> gParticipantHashRateX1000{0};
 static std::mutex gParticipantStatusMutex;
 static std::string gParticipantStatus;
 
+void SelectGenesisParams(bool fTestNetIn)
+{
+    static bool fGenesisParamsSelected = false;
+    static bool fGenesisParamsTestNet = false;
+    if (fGenesisParamsSelected && fGenesisParamsTestNet == fTestNetIn)
+        return;
+
+    fGenesisParamsSelected = true;
+    fGenesisParamsTestNet = fTestNetIn;
+
+    if (fTestNetIn)
+    {
+        GENESIS_NONCE = TESTNET_GENESIS_NONCE;
+        hashGenesisBlock = uint256(TESTNET_GENESIS_HASH);
+        hashGenesisMerkleRoot = uint256(TESTNET_GENESIS_MERKLE);
+    }
+    else
+    {
+        GENESIS_NONCE = MAINNET_GENESIS_NONCE;
+        hashGenesisBlock = uint256(MAINNET_GENESIS_HASH);
+        hashGenesisMerkleRoot = uint256(MAINNET_GENESIS_MERKLE);
+    }
+}
+
+void SelectChainParams(bool fTestNetIn)
+{
+    SelectNetworkParams(fTestNetIn);
+    SelectGenesisParams(fTestNetIn);
+}
+
+static CBlock BuildGenesisBlock()
+{
+    const char* pszTimestamp = IsTestNet() ?
+        TESTNET_GENESIS_TIMESTAMP : MAINNET_GENESIS_TIMESTAMP;
+
+    CTransaction txNew;
+    txNew.vin.resize(1);
+    txNew.vout.resize(1);
+    txNew.vin[0].scriptSig = CScript() << 486604799 << CBigNum(4) <<
+        vector<unsigned char>((unsigned char*)pszTimestamp,
+                              (unsigned char*)pszTimestamp + strlen(pszTimestamp));
+    txNew.vout[0].nValue = 50 * COIN;
+    txNew.vout[0].scriptPubKey = CScript() <<
+        CBigNum("0x5F1DF16B2B704C8A578D0BBAF74D385CDE12C11EE50455F3C438EF4C3FBCF649B6DE611FEAE06279A60939E028A8D65C10B73071A6F16719274855FEB0FD8A6704") <<
+        OP_CHECKSIG;
+
+    CBlock block;
+    block.vtx.push_back(txNew);
+    block.hashPrevBlock = 0;
+    block.hashMerkleRoot = block.BuildMerkleTree();
+    block.nVersion = 1;
+    block.nTime = IsTestNet() ? TESTNET_GENESIS_TIME : MAINNET_GENESIS_TIME;
+    block.nBits = 0x1f0fffff; // = bnProofOfWorkLimit (Bitflash RandomX floor)
+    block.nNonce = GENESIS_NONCE;
+    return block;
+}
+
 void SetParticipantMiningStatus(const std::string& status)
 {
     // Updates the GUI status string only. Logging is done at each call site
@@ -2664,21 +2739,7 @@ bool LoadBlockIndex(bool fAllowNew)
         //   vMerkleTree: 4a5e1e
 
         // Bitflash genesis block -- own header (fair launch, 2026 stable relaunch)
-        char* pszTimestamp = "Bitflash 24/Jul/2026 Fair launch: one CPU one vote, no premine";
-        CTransaction txNew;
-        txNew.vin.resize(1);
-        txNew.vout.resize(1);
-        txNew.vin[0].scriptSig     = CScript() << 486604799 << CBigNum(4) << vector<unsigned char>((unsigned char*)pszTimestamp, (unsigned char*)pszTimestamp + strlen(pszTimestamp));
-        txNew.vout[0].nValue       = 50 * COIN;
-        txNew.vout[0].scriptPubKey = CScript() << CBigNum("0x5F1DF16B2B704C8A578D0BBAF74D385CDE12C11EE50455F3C438EF4C3FBCF649B6DE611FEAE06279A60939E028A8D65C10B73071A6F16719274855FEB0FD8A6704") << OP_CHECKSIG;
-        CBlock block;
-        block.vtx.push_back(txNew);
-        block.hashPrevBlock = 0;
-        block.hashMerkleRoot = block.BuildMerkleTree();
-        block.nVersion = 1;
-        block.nTime    = 1753315200; // 2026-07-24 00:00:00 UTC (stable relaunch)
-        block.nBits    = 0x1f0fffff; // = bnProofOfWorkLimit (Bitflash RandomX floor)
-        block.nNonce   = GENESIS_NONCE;
+        CBlock block = BuildGenesisBlock();
 
         // If the nonce has not been found yet, mine the genesis once (RandomX)
         // and print the values to be hardcoded in the constants above.
diff --git a/src/main.h b/src/main.h
index dc5527e..793c4e8 100644
--- a/src/main.h
+++ b/src/main.h
@@ -59,6 +59,8 @@ extern map<uint256, CBlockIndex*> mapBlockIndex;
 extern uint256 hashGenesisBlock;
 extern uint256 hashGenesisMerkleRoot;
 extern unsigned int GENESIS_NONCE;
+void SelectGenesisParams(bool fTestNetIn);
+void SelectChainParams(bool fTestNetIn);
 extern CBlockIndex* pindexGenesisBlock;
 extern int nBestHeight;
 extern uint256 hashBestChain;
diff --git a/src/main_gui.cpp b/src/main_gui.cpp
index 0a961bf..9f0fec0 100644
--- a/src/main_gui.cpp
+++ b/src/main_gui.cpp
@@ -143,7 +143,7 @@ static void PrintUsage()
     printf("  /onionservice=HOST.onion:PORT  (advertise this node's Tor hidden service)\n");
     printf("\n");
     printf("Network:\n");
-    printf("  /testnet                   (isolated test network datadir, port, and magic)\n");
+    printf("  /testnet                   (isolated test network genesis, datadir, port, and magic)\n");
     printf("  /port=N                    (P2P listen port, default 8433; testnet 18433)\n");
     printf("  /socks=HOST:PORT           (SOCKS5 proxy for Nostr, .btf relay, and onion dials)\n");
     printf("  /tor[=HOST:PORT]           (Tor mode; default SOCKS5 proxy is 127.0.0.1:9050)\n");
@@ -206,7 +206,8 @@ static void ParseStartupArguments(int argc, char* argv[])
     if (arg(argc,argv,"/datadir") || arg(argc,argv,"-datadir"))
         strSetDataDir = argval2(argc, argv, "/datadir", "-datadir");
 
-    SelectNetworkParams(arg(argc, argv, "/testnet") || arg(argc, argv, "-testnet"));
+    bool fUseTestNet = arg(argc, argv, "/testnet") || arg(argc, argv, "-testnet");
+    SelectChainParams(fUseTestNet);
 
     if (arg(argc,argv,"/debug") || arg(argc,argv,"-debug"))
         fDebug = true;
diff --git a/src/readme.txt b/src/readme.txt
index 5d62791..810e8b7 100644
--- a/src/readme.txt
+++ b/src/readme.txt
@@ -41,7 +41,7 @@ The resulting executable is src/bitflash.exe.
 
 Command-line options (in addition to the original ones)
 -------------------------------------------------------
-  /testnet       use isolated test network datadir, port 18433, and message magic
+  /testnet       use isolated test network genesis, datadir, port 18433, and message magic
   /port=N        listen on P2P port N (default 8433; testnet default 18433)
   /socks=HOST:PORT
                  route outbound Nostr, .btf rendezvous, and direct onion peer
diff --git a/src/selftest.cpp b/src/selftest.cpp
index 30bd28e..1a72e3a 100644
--- a/src/selftest.cpp
+++ b/src/selftest.cpp
@@ -3085,7 +3085,7 @@ static int RunNetworkParamsSelfTest()
     std::string strOldDataDir = strSetDataDir;
     try
     {
-        SelectNetworkParams(false);
+        SelectChainParams(false);
         nFail += Check(!IsTestNet(), "starts on mainnet after explicit selection") ? 0 : 1;
         nFail += Check(ntohs(GetDefaultPort()) == MAINNET_PORT,
                        "mainnet default P2P port is 8433") ? 0 : 1;
@@ -3095,8 +3095,11 @@ static int RunNetworkParamsSelfTest()
         CMessageHeader mainHeader("ping", 0);
         char mainMagic[4];
         memcpy(mainMagic, mainHeader.pchMessageStart, sizeof(mainMagic));
+        uint256 mainGenesis = hashGenesisBlock;
+        uint256 mainMerkle = hashGenesisMerkleRoot;
+        unsigned int mainNonce = GENESIS_NONCE;
 
-        SelectNetworkParams(true);
+        SelectChainParams(true);
         nFail += Check(IsTestNet(), "testnet selection is sticky") ? 0 : 1;
         nFail += Check(ntohs(GetDefaultPort()) == TESTNET_PORT,
                        "testnet default P2P port is 18433") ? 0 : 1;
@@ -3106,6 +3109,14 @@ static int RunNetworkParamsSelfTest()
         CMessageHeader testHeader("ping", 0);
         nFail += Check(memcmp(mainMagic, testHeader.pchMessageStart, sizeof(mainMagic)) != 0,
                        "testnet message magic differs from mainnet") ? 0 : 1;
+        nFail += Check(hashGenesisBlock != mainGenesis &&
+                       hashGenesisMerkleRoot != mainMerkle &&
+                       GENESIS_NONCE != mainNonce,
+                       "testnet genesis constants differ from mainnet") ? 0 : 1;
+        nFail += Check(hashGenesisBlock == uint256("0xa9d11c6d697bcb7aea0653bc088b12dcf9f44e732df205162cf085fd9d9963eb") &&
+                       hashGenesisMerkleRoot == uint256("0x510b293105e3ff85b8d4c3920e357f85d1a86bf199eb4e7d11f04f380030ec5c") &&
+                       GENESIS_NONCE == 3199,
+                       "testnet genesis constants are pinned") ? 0 : 1;
 
         std::string tmp;
         if (!MakeTempDir(tmp))
@@ -3115,9 +3126,9 @@ static int RunNetworkParamsSelfTest()
         else
         {
             strSetDataDir = tmp;
-            SelectNetworkParams(false);
+            SelectChainParams(false);
             std::string mainDir = GetAppDir();
-            SelectNetworkParams(true);
+            SelectChainParams(true);
             std::string testDir = GetAppDir();
             nFail += Check(mainDir == tmp,
                            "mainnet uses the selected data directory") ? 0 : 1;
@@ -3138,7 +3149,7 @@ static int RunNetworkParamsSelfTest()
     }
 
     strSetDataDir = strOldDataDir;
-    SelectNetworkParams(false);
+    SelectChainParams(false);
 
     printf("%s (%d failure%s)\n", nFail == 0 ? "ALL TESTS PASSED" : "TESTS FAILED",
            nFail, nFail == 1 ? "" : "s");