wallet: Move listdescriptors retrieving from RPC to CWallet

diff --git a/src/wallet/CMakeLists.txt b/src/wallet/CMakeLists.txt
index 36fd3ef9..040569f7 100644
--- a/src/wallet/CMakeLists.txt
+++ b/src/wallet/CMakeLists.txt
@@ -10,6 +10,7 @@ add_library(bitcoin_wallet STATIC EXCLUDE_FROM_ALL
   crypter.cpp
   db.cpp
   dump.cpp
+  export.cpp
   external_signer_scriptpubkeyman.cpp
   feebumper.cpp
   fees.cpp
diff --git a/src/wallet/export.cpp b/src/wallet/export.cpp
new file mode 100644
index 00000000..9c042d3b
--- /dev/null
+++ b/src/wallet/export.cpp
@@ -0,0 +1,39 @@
+// Copyright (c) 2026-present The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or https://www.opensource.org/licenses/mit-license.php.
+
+#include <wallet/export.h>
+
+#include <util/expected.h>
+#include <wallet/scriptpubkeyman.h>
+#include <wallet/wallet.h>
+
+namespace wallet {
+util::Expected<std::vector<WalletDescInfo>, std::string> ExportDescriptors(const CWallet& wallet, bool export_private)
+{
+    AssertLockHeld(wallet.cs_wallet);
+    std::vector<WalletDescInfo> wallet_descriptors;
+    for (const auto& spk_man : wallet.GetAllScriptPubKeyMans()) {
+        const auto desc_spk_man = dynamic_cast<DescriptorScriptPubKeyMan*>(spk_man);
+        if (!desc_spk_man) {
+            return util::Unexpected{"Unexpected ScriptPubKey manager type."};
+        }
+        LOCK(desc_spk_man->cs_desc_man);
+        const auto& wallet_descriptor = desc_spk_man->GetWalletDescriptor();
+        std::string descriptor;
+        if (!Assume(desc_spk_man->GetDescriptorString(descriptor, export_private))) {
+            return util::Unexpected{"Can't get descriptor string."};
+        }
+        const bool is_range = wallet_descriptor.descriptor->IsRange();
+        wallet_descriptors.emplace_back(
+            descriptor,
+            wallet_descriptor.creation_time,
+            wallet.IsActiveScriptPubKeyMan(*desc_spk_man),
+            wallet.IsInternalScriptPubKeyMan(desc_spk_man),
+            is_range ? std::optional(std::make_pair(wallet_descriptor.range_start, wallet_descriptor.range_end)) : std::nullopt,
+            wallet_descriptor.next_index
+        );
+    }
+    return wallet_descriptors;
+}
+} // namespace wallet
diff --git a/src/wallet/export.h b/src/wallet/export.h
new file mode 100644
index 00000000..d83600be
--- /dev/null
+++ b/src/wallet/export.h
@@ -0,0 +1,32 @@
+// Copyright (c) 2026-present The Bitcoin Core developers
+// Distributed under the MIT software license, see the accompanying
+// file COPYING or https://www.opensource.org/licenses/mit-license.php.
+
+#ifndef BITCOIN_WALLET_EXPORT_H
+#define BITCOIN_WALLET_EXPORT_H
+
+#include <threadsafety.h>
+#include <util/expected.h>
+#include <wallet/wallet.h>
+
+#include <optional>
+#include <vector>
+
+namespace wallet {
+// Struct containing all of the info from WalletDescriptor, except with the descriptor as a string,
+// and without its ID or cache.
+// Used when exporting descriptors from the wallet.
+struct WalletDescInfo {
+    std::string descriptor;
+    uint64_t creation_time;
+    bool active;
+    std::optional<bool> internal;
+    std::optional<std::pair<int64_t,int64_t>> range;
+    int64_t next_index;
+};
+
+//! Export the descriptors from a wallet so that they can be imported elsewhere
+util::Expected<std::vector<WalletDescInfo>, std::string> ExportDescriptors(const CWallet& wallet, bool export_private) EXCLUSIVE_LOCKS_REQUIRED(wallet.cs_wallet);
+} // namespace wallet
+
+#endif // BITCOIN_WALLET_EXPORT_H
diff --git a/src/wallet/rpc/backup.cpp b/src/wallet/rpc/backup.cpp
index 396be628..9c58e0fe 100644
--- a/src/wallet/rpc/backup.cpp
+++ b/src/wallet/rpc/backup.cpp
@@ -21,6 +21,7 @@
 #include <util/fs.h>
 #include <util/time.h>
 #include <util/translation.h>
+#include <wallet/export.h>
 #include <wallet/rpc/util.h>
 #include <wallet/wallet.h>
 
@@ -526,38 +527,11 @@ RPCMethod listdescriptors()
     }
 
     LOCK(wallet->cs_wallet);
-
-    const auto active_spk_mans = wallet->GetActiveScriptPubKeyMans();
-
-    struct WalletDescInfo {
-        std::string descriptor;
-        uint64_t creation_time;
-        bool active;
-        std::optional<bool> internal;
-        std::optional<std::pair<int64_t,int64_t>> range;
-        int64_t next_index;
-    };
-
-    std::vector<WalletDescInfo> wallet_descriptors;
-    for (const auto& spk_man : wallet->GetAllScriptPubKeyMans()) {
-        const auto desc_spk_man = dynamic_cast<DescriptorScriptPubKeyMan*>(spk_man);
-        if (!desc_spk_man) {
-            throw JSONRPCError(RPC_WALLET_ERROR, "Unexpected ScriptPubKey manager type.");
-        }
-        LOCK(desc_spk_man->cs_desc_man);
-        const auto& wallet_descriptor = desc_spk_man->GetWalletDescriptor();
-        std::string descriptor;
-        CHECK_NONFATAL(desc_spk_man->GetDescriptorString(descriptor, priv));
-        const bool is_range = wallet_descriptor.descriptor->IsRange();
-        wallet_descriptors.push_back({
-            descriptor,
-            wallet_descriptor.creation_time,
-            active_spk_mans.contains(desc_spk_man),
-            wallet->IsInternalScriptPubKeyMan(desc_spk_man),
-            is_range ? std::optional(std::make_pair(wallet_descriptor.range_start, wallet_descriptor.range_end)) : std::nullopt,
-            wallet_descriptor.next_index
-        });
+    util::Expected<std::vector<WalletDescInfo>, std::string> exported = ExportDescriptors(*wallet, priv);
+    if (!exported) {
+        throw JSONRPCError(RPC_WALLET_ERROR, exported.error());
     }
+    std::vector<WalletDescInfo> wallet_descriptors = *exported;
 
     std::sort(wallet_descriptors.begin(), wallet_descriptors.end(), [](const auto& a, const auto& b) {
         return a.descriptor < b.descriptor;
diff --git a/src/wallet/wallet.h b/src/wallet/wallet.h
index 47701d7e..9f964e50 100644
--- a/src/wallet/wallet.h
+++ b/src/wallet/wallet.h
@@ -23,6 +23,7 @@
 #include <tinyformat.h>
 #include <uint256.h>
 #include <util/btcsignals.h>
+#include <util/expected.h>
 #include <util/fs.h>
 #include <util/hasher.h>
 #include <util/log.h>