this is insane but sure

src/log.cpp

@@ -1,5 +1,7 @@
 #include "log.h"
 
+#include <filesystem>
+#include <iterator>
 #include <print>
 
 #include "sdl.h"
@@ -9,6 +11,37 @@ using namespace anm2ed::util;
 
 namespace anm2ed
 {
+  namespace
+  {
+    bool ensure_utf8_bom(const std::filesystem::path& path)
+    {
+      std::error_code ec{};
+      if (!std::filesystem::exists(path, ec)) return false;
+
+      std::ifstream existing(path, std::ios::binary);
+      if (!existing) return false;
+
+      char bom[3]{};
+      existing.read(bom, sizeof(bom));
+      auto bytesRead = existing.gcount();
+      auto hasBom = bytesRead == sizeof(bom) && bom[0] == '\xEF' && bom[1] == '\xBB' && bom[2] == '\xBF';
+      if (hasBom) return true;
+
+      existing.clear();
+      existing.seekg(0, std::ios::beg);
+      std::string contents((std::istreambuf_iterator<char>(existing)), std::istreambuf_iterator<char>());
+      existing.close();
+
+      std::ofstream output(path, std::ios::binary | std::ios::trunc);
+      if (!output) return false;
+      output << "\xEF\xBB\xBF";
+      output.write(contents.data(), static_cast<std::streamsize>(contents.size()));
+      output.close();
+
+      return true;
+    }
+  }
+
   void Logger::write_raw(const std::string& message)
   {
     std::println("{}", message);
@@ -26,7 +59,17 @@ namespace anm2ed
   void Logger::error(const std::string& message) { write(ERROR, message); }
   void Logger::fatal(const std::string& message) { write(FATAL, message); }
   void Logger::command(const std::string& message) { write(COMMAND, message); }
-  void Logger::open(const std::filesystem::path& path) { file.open(path, std::ios::out | std::ios::app); }
+  void Logger::open(const std::filesystem::path& path)
+  {
+    std::error_code ec{};
+    auto exists = std::filesystem::exists(path, ec);
+    if (exists) ensure_utf8_bom(path);
+
+    file.open(path, std::ios::out | std::ios::app);
+    if (!file.is_open()) return;
+
+    if (!exists) file << "\xEF\xBB\xBF";
+  }
 
   std::filesystem::path Logger::path() { return sdl::preferences_directory_get() / "log.txt"; }