fix: derivation path for cj - add missing /4' (cj purpose)

Author: knst

src/wallet/rpc/backup.cpp

@@ -2039,7 +2039,7 @@ RPCHelpMan listdescriptors()
             spk.pushKV("internal", wallet->GetScriptPubKeyMan(true) == desc_spk_man);
         }
         if (type != std::nullopt) {
-            std::string match = strprintf("/%d'/%s'/0'", BIP32_PURPOSE_FEATURE, Params().ExtCoinType());
+            std::string match = strprintf("/%d'/%s'/4'/0'", BIP32_PURPOSE_FEATURE, Params().ExtCoinType());
             bool is_cj = descriptor.find(match) != std::string::npos;
             if (is_cj) {
                 spk.pushKV("internal", false);

src/wallet/scriptpubkeyman.cpp

@@ -2100,8 +2100,10 @@ bool DescriptorScriptPubKeyMan::SetupDescriptorGeneration(const CExtKey& master_
 
     // Build descriptor string
     std::string desc_prefix = strprintf("pkh(%s/%d'/%d'", xpub, type == PathDerivationType::DIP0009_CoinJoin ? BIP32_PURPOSE_FEATURE : BIP32_PURPOSE_STANDARD, Params().ExtCoinType());
+    if (type == PathDerivationType::DIP0009_CoinJoin) {
+        desc_prefix += "/4'";
+    }
     std::string desc_suffix = "/*)";
-
     std::string internal_path = (type == PathDerivationType::BIP44_Internal) ? "/1" : "/0";
     std::string desc_str = desc_prefix + "/0'" + internal_path + desc_suffix;