Merge upstream v1.2.20 into the fork

Merges upstream tag v1.2.20 (6aa3dade) into our 1.2.19+sec tree. The merge
base is bc3de30's descendant 9e39a50 -- upstream's own v1.2.19 -- so this is
an ordinary three-way merge, not a replay. Five conflict blocks in four
files, all resolved below.

No consensus change. CheckBlock, ConnectBlock, DisconnectBlock, ConnectInputs,
AcceptBlock, AcceptTransaction, GetNextWorkRequired and GetBlockValue hash
identical to v1.2.19; script.cpp and script.h are byte-identical on both
sides. main.cpp is +3 lines and main.h +2, all wallet-backend plumbing.
rpc.cpp is untouched, so the payout ledger arrives unchanged.

Makefile, VERSION. OURS, renumbered. 1.2.20+sec, for the same reason 1.2.19
carried +sec: this tree is not the upstream release of that number and the
string names every release artifact.

Makefile, AppImage recipe. OURS for the AppDir path, THEIRS for the bundled
library. Upstream's hunk reverts the icon paths to a hardcoded
/tmp/bitflash.AppDir, which is the local-user pre-placement hazard the fork
moved out of /tmp in the first place; taking their side wholesale would have
reintroduced it silently, inside a conflict about something else. The AppDir
stays $(APPDIR), and libsqlite3.so.0 joins the bundled list, which the new
backend genuinely needs.

src/Makefile, src/makefile.mingw, HEADERS. BOTH. Ours drops market.h,
theirs adds wallet_sqlite.h; the resolution does both. NODE_OBJS auto-merged
correctly in both files -- obj/wallet_sqlite.o present, obj/market.o still
gone -- and was verified rather than assumed, because that line has trapped
this fork before.

src/selftest.cpp, known-tests list. BOTH, union. Upstream adds eight
wallet-storage tests, we keep payout-ledger. The dispatch chain itself
auto-merged and still routes payout-ledger to RunPayoutLedgerSelfTest.

Hardening verified intact after merge: the TLS 1.2 floor in nostr.cpp, the
/rvrelay pin, opt-in managed Tor, strict sig3-on-onion descriptor
verification, and the marketplace removal. Upstream shipped no build logs or
__pycache__ this time; the three added files are docs/storage.md and
src/wallet_sqlite.{cpp,h}.

The SQLite backend this release introduces is NOT enabled here. An existing
wallet.dat resolves to Berkeley DB on every branch of the new selection
logic, and the conversion wizard is GUI-only and not compiled into the
headless node. The review findings that gate ever turning it on -- the
non-atomic backend marker, the connection-wide WriteHDMaster transaction,
and the encrypt-swap crash window -- are recorded on the tracker, not fixed
here.

1 files changed, 120 insertions, 0 deletions

diff --git a/src/wallet_sqlite.h b/src/wallet_sqlite.h
new file mode 100644
index 0000000..d27e13a
--- /dev/null
+++ b/src/wallet_sqlite.h
@@ -0,0 +1,120 @@
+// Copyright (c) 2026 Bitflash developers
+// Distributed under the MIT/X11 software license.
+
+#ifndef BITFLASH_WALLET_SQLITE_H
+#define BITFLASH_WALLET_SQLITE_H
+
+#include <sqlite3.h>
+
+class CWalletRecordVisitor;
+
+class CWalletDBSQLite
+{
+public:
+    CWalletDBSQLite();
+    ~CWalletDBSQLite();
+
+    bool Open(const string& strPath, string& strError);
+    bool OpenReadOnly(const string& strPath, string& strError);
+    void Close();
+
+    bool BeginTransaction(string& strError);
+    bool CommitTransaction(string& strError);
+    bool RollbackTransaction(string& strError);
+    bool Checkpoint(string& strError);
+
+    bool WriteRecord(const vector<unsigned char>& vchKey,
+                     const vector<unsigned char>& vchValue,
+                     string& strError,
+                     bool fOverwrite=true);
+    bool ReadRecord(const vector<unsigned char>& vchKey,
+                    vector<unsigned char>& vchValueRet,
+                    string& strError);
+    bool EraseRecord(const vector<unsigned char>& vchKey,
+                     string& strError);
+    bool ScanRecords(CWalletRecordVisitor& visitor, string& strError);
+    bool CountRecords(int& nRecordsRet, string& strError);
+
+    template<typename K, typename T>
+    bool WriteTypedRecord(const K& key, const T& value, string& strError,
+                          bool fOverwrite=true)
+    {
+        CDataStream ssKey(SER_DISK);
+        ssKey.reserve(1000);
+        ssKey << key;
+
+        CDataStream ssValue(SER_DISK);
+        ssValue.reserve(10000);
+        ssValue << value;
+
+        vector<unsigned char> vchKey(ssKey.begin(), ssKey.end());
+        vector<unsigned char> vchValue(ssValue.begin(), ssValue.end());
+        bool fOk = WriteRecord(vchKey, vchValue, strError, fOverwrite);
+
+        if (!vchKey.empty())
+            memset(&vchKey[0], 0, vchKey.size());
+        if (!vchValue.empty())
+            memset(&vchValue[0], 0, vchValue.size());
+        if (!ssKey.empty())
+            memset(&ssKey[0], 0, ssKey.size());
+        if (!ssValue.empty())
+            memset(&ssValue[0], 0, ssValue.size());
+        return fOk;
+    }
+
+    template<typename K, typename T>
+    bool ReadTypedRecord(const K& key, T& valueRet, string& strError)
+    {
+        CDataStream ssKey(SER_DISK);
+        ssKey.reserve(1000);
+        ssKey << key;
+        vector<unsigned char> vchKey(ssKey.begin(), ssKey.end());
+
+        vector<unsigned char> vchValue;
+        bool fOk = ReadRecord(vchKey, vchValue, strError);
+        if (!vchKey.empty())
+            memset(&vchKey[0], 0, vchKey.size());
+        if (!ssKey.empty())
+            memset(&ssKey[0], 0, ssKey.size());
+        if (!fOk)
+            return false;
+
+        CDataStream ssValue(vchValue, SER_DISK);
+        ssValue >> valueRet;
+        bool fReadOk = !ssValue.fail();
+        if (!vchValue.empty())
+            memset(&vchValue[0], 0, vchValue.size());
+        if (!ssValue.empty())
+            memset(&ssValue[0], 0, ssValue.size());
+        if (!fReadOk)
+            strError = "SQLite wallet record could not be deserialized";
+        return fReadOk;
+    }
+
+    template<typename K>
+    bool EraseTypedRecord(const K& key, string& strError)
+    {
+        CDataStream ssKey(SER_DISK);
+        ssKey.reserve(1000);
+        ssKey << key;
+        vector<unsigned char> vchKey(ssKey.begin(), ssKey.end());
+
+        bool fOk = EraseRecord(vchKey, strError);
+        if (!vchKey.empty())
+            memset(&vchKey[0], 0, vchKey.size());
+        if (!ssKey.empty())
+            memset(&ssKey[0], 0, ssKey.size());
+        return fOk;
+    }
+
+private:
+    sqlite3* pdb;
+
+    bool Exec(const char* pszSql, string& strError);
+    bool InitSchema(string& strError);
+
+    CWalletDBSQLite(const CWalletDBSQLite&);
+    void operator=(const CWalletDBSQLite&);
+};
+
+#endif