wallet: use in-memory SQLite for temporary wallet in exportwatchonlywallet

diff --git a/src/wallet/export.cpp b/src/wallet/export.cpp
index 6f170dd7..1df51b6b 100644
--- a/src/wallet/export.cpp
+++ b/src/wallet/export.cpp
@@ -9,6 +9,7 @@
 #include <util/expected.h>
 #include <wallet/scriptpubkeyman.h>
 #include <wallet/context.h>
+#include <wallet/sqlite.h>
 #include <wallet/wallet.h>
 
 #include <fstream>
@@ -69,40 +70,15 @@ util::Result<std::string> ExportWatchOnlyWallet(const CWallet& wallet, const fs:
         return util::Error{_("Error: Wallet has no descriptors to export")};
     }
 
-    // Setup DatabaseOptions to create a new sqlite database
-    DatabaseOptions options;
-    options.require_existing = false;
-    options.require_create = true;
-    options.require_format = DatabaseFormat::SQLITE;
-
     // Make the wallet with the same flags as this wallet, but without private keys
-    options.create_flags = wallet.GetWalletFlags() | WALLET_FLAG_DISABLE_PRIVATE_KEYS;
+    const uint64_t create_flags = wallet.GetWalletFlags() | WALLET_FLAG_DISABLE_PRIVATE_KEYS;
 
-    // Make the watchonly wallet
-    DatabaseStatus status;
+    // Create the temporary watchonly wallet in memory to avoid leaving files on disk
     std::vector<bilingual_str> warnings;
-    std::string wallet_name = wallet.GetName() + "_watchonly_temp";
     bilingual_str error;
-    std::unique_ptr<WalletDatabase> database = MakeWalletDatabase(wallet_name, options, status, error);
-    if (!database) {
-        return util::Error{strprintf(_("Wallet file creation failed: %s"), error)};
-    }
-
-    // Always remove the temporary wallet files, even when returning early on error.
-    std::shared_ptr<CWallet> watchonly_wallet;
-    fs::path wallet_path = fs::PathFromString(database->Filename()).parent_path();
-    std::vector<fs::path> cleanup_files = database->Files();
-    auto cleanup_watchonly_wallet = interfaces::MakeCleanupHandler([&watchonly_wallet, &wallet_path, &cleanup_files] {
-        if (watchonly_wallet) watchonly_wallet.reset();
-        for (const auto& file : cleanup_files) {
-            fs::remove(file);
-        }
-        fs::remove(wallet_path);
-    });
-
     WalletContext empty_context;
     empty_context.args = context.args;
-    watchonly_wallet = CWallet::CreateNew(empty_context, wallet_name, std::move(database), options.create_flags, /*born_encrypted=*/false, error, warnings);
+    std::shared_ptr<CWallet> watchonly_wallet = CWallet::CreateNew(empty_context, /*name=*/wallet.GetName() + "_watchonly_temp", MakeInMemoryWalletDatabase(), create_flags, /*born_encrypted=*/false, error, warnings);
     if (!watchonly_wallet) {
         return util::Error{strprintf(_("Error: Failed to create new watchonly wallet. %s"), error)};
     }
diff --git a/src/wallet/sqlite.cpp b/src/wallet/sqlite.cpp
index 28123ecf..fa2abc93 100644
--- a/src/wallet/sqlite.cpp
+++ b/src/wallet/sqlite.cpp
@@ -722,6 +722,15 @@ std::unique_ptr<SQLiteDatabase> MakeSQLiteDatabase(const fs::path& path, const D
     }
 }
 
+InMemoryWalletDatabase::InMemoryWalletDatabase()
+    : SQLiteDatabase(fs::path{}, fs::path{":memory:"}, DatabaseOptions(), SQLITE_OPEN_MEMORY)
+{}
+
+std::unique_ptr<WalletDatabase> MakeInMemoryWalletDatabase()
+{
+    return std::make_unique<InMemoryWalletDatabase>();
+}
+
 std::string SQLiteDatabaseVersion()
 {
     return std::string(sqlite3_libversion());
diff --git a/src/wallet/sqlite.h b/src/wallet/sqlite.h
index 3a35bb24..f3268b4b 100644
--- a/src/wallet/sqlite.h
+++ b/src/wallet/sqlite.h
@@ -175,8 +175,19 @@ public:
     bool m_use_unsafe_sync;
 };
 
+/** An in-memory SQLiteDatabase. Used as a temporary build artifact where no
+ *  on-disk persistence is needed. */
+class InMemoryWalletDatabase : public SQLiteDatabase
+{
+public:
+    InMemoryWalletDatabase();
+    std::vector<fs::path> Files() override { return {}; }
+};
+
 std::unique_ptr<SQLiteDatabase> MakeSQLiteDatabase(const fs::path& path, const DatabaseOptions& options, DatabaseStatus& status, bilingual_str& error);
 
+std::unique_ptr<WalletDatabase> MakeInMemoryWalletDatabase();
+
 std::string SQLiteDatabaseVersion();
 } // namespace wallet
 
diff --git a/src/wallet/test/util.cpp b/src/wallet/test/util.cpp
index 43cfd40f..19281be6 100644
--- a/src/wallet/test/util.cpp
+++ b/src/wallet/test/util.cpp
@@ -116,7 +116,7 @@ CTxDestination getNewDestination(CWallet& w, OutputType output_type)
 }
 
 MockableSQLiteDatabase::MockableSQLiteDatabase()
-    : SQLiteDatabase(fs::PathFromString("mock/"), fs::PathFromString("mock/wallet.dat"), DatabaseOptions(), SQLITE_OPEN_MEMORY)
+    : InMemoryWalletDatabase()
 {}
 
 std::unique_ptr<WalletDatabase> CreateMockableWalletDatabase()
diff --git a/src/wallet/test/util.h b/src/wallet/test/util.h
index 9a407d31..0af46e55 100644
--- a/src/wallet/test/util.h
+++ b/src/wallet/test/util.h
@@ -56,7 +56,7 @@ public:
 
 /** A WalletDatabase whose contents and return values can be modified as needed for testing
  **/
-class MockableSQLiteDatabase : public SQLiteDatabase
+class MockableSQLiteDatabase : public InMemoryWalletDatabase
 {
 public:
     MockableSQLiteDatabase();
@@ -64,7 +64,6 @@ public:
     bool Backup(const std::string& strDest) const override { return true; }
 
     std::string Filename() override { return "mockable"; }
-    std::vector<fs::path> Files() override { return {}; }
     std::string Format() override { return "sqlite-mock"; }
     std::unique_ptr<DatabaseBatch> MakeBatch() override { return std::make_unique<MockableSQLiteBatch>(*this); }
 };