修复问题

backend/library/include/adminive/managed.hpp

@@ -297,11 +297,12 @@ public:
                 std::invoke(std::forward<Function>(function), value_);
             });
         } else {
-            std::optional<std::remove_cvref_t<Result>> result;
+            using Value_Result = std::remove_cvref_t<Result>;
+            std::optional<Value_Result> result;
             this->with_all_writable_locked([&](auto&) {
                 result.emplace(std::invoke(std::forward<Function>(function), value_));
             });
-            return std::move(*result);
+            return Value_Result(std::move(*result));
         }
     }
     T snapshot() const requires std::copy_constructible<T> {

backend/service/tests/managed_test.cpp

@@ -4,6 +4,7 @@
 #include "adminive_test.hpp"
 #include <string>
 #include <thread>
+#include <tuple>
 namespace managed_test {
 using Json = nlohmann::json;
 struct Section_Config {
@@ -108,6 +109,12 @@ int main() {
         value = 12;
     });
     ADMINIVE_CHECK(Probe_Lock::exclusive_locks.load(std::memory_order_relaxed) == 1);
+    const auto [written_value, write_message] = guarded.write([](Section_Config& value) {
+        value.backend_value = 14;
+        return std::tuple{value.backend_value, std::string(128, 'x')};
+    });
+    ADMINIVE_CHECK(written_value == 14);
+    ADMINIVE_CHECK(write_message == std::string(128, 'x'));
     Probe_Lock::reset();
     unsynchronized.write([](int& value) {
         value = 13;