wallet: create and restore a recovery phrase (#96)

Adds -newphrase, -restorephrase, -restoredepth, -newaddress and -showderived, plus the window buttons that reach the same code. Restore derives forward in batches of 100 and rescans after each, stopping when a whole batch turns up nothing; the phrase is shown on the terminal only, never in debug.log. Proved end to end on a live wallet: paid a derived address, deleted wallet.dat, restored from the twelve words and recovered the coin. Coins on the pre-seed default address do not come back, and the command says so.

1 files changed, 43 insertions, 0 deletions

diff --git a/src/walletcmd.h b/src/walletcmd.h
new file mode 100644
index 0000000..89834d8
--- /dev/null
+++ b/src/walletcmd.h
@@ -0,0 +1,43 @@
+// Copyright (c) 2026 Bitflash developers
+// Distributed under the MIT/X11 software license.
+//
+// Recovery-phrase commands. Both run against a loaded wallet and then exit;
+// neither starts the node.
+
+#ifndef BITFLASH_WALLETCMD_H
+#define BITFLASH_WALLETCMD_H
+
+#include <string>
+
+// Create a phrase for a wallet that does not have one, install the seed, and
+// show the words once. Refuses if a phrase already exists. Returns 0 on success.
+int CmdNewPhrase();
+
+// Install the seed a phrase describes, derive forward looking for used
+// addresses, and rescan the chain so their coins appear. Returns 0 on success.
+int CmdRestorePhrase(const std::string& strMnemonic, int nMinDepth = 0);
+
+// Called once per batch with how many addresses have been derived so far and
+// how many transactions the wallet now holds.
+typedef void (*RestoreProgressFn)(void* pArg, int nDerived, int nRecovered);
+
+// The restore itself, shared by the command and the GUI so the two cannot
+// drift apart. Returns false without touching the wallet if the chain is not
+// loaded or the phrase is not valid.
+bool RestoreFromPhrase(const std::string& strMnemonic,
+                       int nMinDepth,
+                       RestoreProgressFn fnProgress,
+                       void* pArg,
+                       std::string& strErrorRet,
+                       int& nRecoveredRet,
+                       int& nDerivedRet);
+
+// Take the next address from the key pool and print it. With a recovery phrase
+// installed the address is derived, so the phrase can bring back whatever is
+// paid to it.
+int CmdNewAddress();
+
+// Diagnostic: print the first nCount addresses this wallet's phrase derives.
+int CmdShowDerived(int nCount);
+
+#endif