diff --git a/CMakeLists.txt b/CMakeLists.txt
index 419f0faff..b6db155d3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -101,6 +101,7 @@ list(APPEND MINECRAFT_SERVER_SOURCES
   "${CMAKE_CURRENT_SOURCE_DIR}/Minecraft.Server/Console/commands/CliCommandList.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/Minecraft.Server/Console/commands/CliCommandTp.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/Minecraft.Server/Console/commands/CliCommandGamemode.cpp"
+  "${CMAKE_CURRENT_SOURCE_DIR}/Minecraft.Server/Common/FileUtils.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/Minecraft.Server/Common/StringUtils.cpp"
   "${CMAKE_CURRENT_SOURCE_DIR}/Minecraft.Server/vendor/linenoise/linenoise.c"
 )
diff --git a/Minecraft.Server/Common/FileUtils.cpp b/Minecraft.Server/Common/FileUtils.cpp
new file mode 100644
index 000000000..50eeeb72e
--- /dev/null
+++ b/Minecraft.Server/Common/FileUtils.cpp
@@ -0,0 +1,146 @@
+#include "stdafx.h"
+
+#include "FileUtils.h"
+
+#include "StringUtils.h"
+
+#include <io.h>
+#include <stdio.h>
+
+namespace ServerRuntime
+{
+	namespace FileUtils
+	{
+		namespace
+		{
+			static std::wstring ToWidePath(const std::string &filePath)
+			{
+				return StringUtils::Utf8ToWide(filePath);
+			}
+		}
+
+		unsigned long long GetCurrentUtcFileTime()
+		{
+			FILETIME now = {};
+			GetSystemTimeAsFileTime(&now);
+
+			ULARGE_INTEGER value = {};
+			value.LowPart = now.dwLowDateTime;
+			value.HighPart = now.dwHighDateTime;
+			return value.QuadPart;
+		}
+
+		bool ReadTextFile(const std::string &filePath, std::string *outText)
+		{
+			if (outText == nullptr)
+			{
+				return false;
+			}
+
+			outText->clear();
+
+			const std::wstring widePath = ToWidePath(filePath);
+			if (widePath.empty())
+			{
+				return false;
+			}
+
+			FILE *inFile = nullptr;
+			if (_wfopen_s(&inFile, widePath.c_str(), L"rb") != 0 || inFile == nullptr)
+			{
+				return false;
+			}
+
+			if (fseek(inFile, 0, SEEK_END) != 0)
+			{
+				fclose(inFile);
+				return false;
+			}
+
+			long fileSize = ftell(inFile);
+			if (fileSize < 0)
+			{
+				fclose(inFile);
+				return false;
+			}
+
+			if (fseek(inFile, 0, SEEK_SET) != 0)
+			{
+				fclose(inFile);
+				return false;
+			}
+
+			if (fileSize == 0)
+			{
+				fclose(inFile);
+				return true;
+			}
+
+			outText->resize((size_t)fileSize);
+			size_t bytesRead = fread(&(*outText)[0], 1, (size_t)fileSize, inFile);
+			fclose(inFile);
+
+			if (bytesRead != (size_t)fileSize)
+			{
+				outText->clear();
+				return false;
+			}
+
+			return true;
+		}
+
+		bool WriteTextFileAtomic(const std::string &filePath, const std::string &text)
+		{
+			const std::wstring widePath = ToWidePath(filePath);
+			if (widePath.empty())
+			{
+				return false;
+			}
+
+			const std::wstring tmpPath = widePath + L".tmp";
+
+			FILE *outFile = nullptr;
+			if (_wfopen_s(&outFile, tmpPath.c_str(), L"wb") != 0 || outFile == nullptr)
+			{
+				return false;
+			}
+
+			if (!text.empty())
+			{
+				size_t bytesWritten = fwrite(text.data(), 1, text.size(), outFile);
+				if (bytesWritten != text.size())
+				{
+					fclose(outFile);
+					DeleteFileW(tmpPath.c_str());
+					return false;
+				}
+			}
+
+			if (fflush(outFile) != 0 || _commit(_fileno(outFile)) != 0)
+			{
+				fclose(outFile);
+				DeleteFileW(tmpPath.c_str());
+				return false;
+			}
+			fclose(outFile);
+
+			DWORD attrs = GetFileAttributesW(widePath.c_str());
+			if (attrs != INVALID_FILE_ATTRIBUTES && ((attrs & FILE_ATTRIBUTE_DIRECTORY) == 0))
+			{
+				// Replace the destination without deleting the last known-good file first.
+				if (ReplaceFileW(widePath.c_str(), tmpPath.c_str(), nullptr, REPLACEFILE_IGNORE_MERGE_ERRORS, nullptr, nullptr))
+				{
+					return true;
+				}
+			}
+
+			if (MoveFileExW(tmpPath.c_str(), widePath.c_str(), MOVEFILE_REPLACE_EXISTING | MOVEFILE_WRITE_THROUGH))
+			{
+				return true;
+			}
+
+			// Keep the temp file on failure so the original file remains recoverable and the caller can inspect the write result.
+			return false;
+		}
+	}
+}
\ No newline at end of file
diff --git a/Minecraft.Server/Common/FileUtils.h b/Minecraft.Server/Common/FileUtils.h
new file mode 100644
index 000000000..96e398ccf
--- /dev/null
+++ b/Minecraft.Server/Common/FileUtils.h
@@ -0,0 +1,25 @@
+#pragma once
+
+#include <string>
+
+namespace ServerRuntime
+{
+	namespace FileUtils
+	{
+		/**
+		 * Reads the full UTF-8 path target into memory without interpreting JSON or line endings
+		 * UTF-8パスのテキストファイル全体をそのまま読み込む
+		 */
+		bool ReadTextFile(const std::string &filePath, std::string *outText);
+		/**
+		 * Writes text through a same-directory temporary file and publishes it with a single replacement step
+		 * 同一ディレクトリの一時ファイル経由で安全に書き換える
+		 */
+		bool WriteTextFileAtomic(const std::string &filePath, const std::string &text);
+		/**
+		 * Returns the current UTC timestamp encoded in Windows FILETIME units for expiry comparisons
+		 * 期限判定用に現在UTC時刻をWindows FILETIME単位で返す
+		 */
+		unsigned long long GetCurrentUtcFileTime();
+	}
+}
\ No newline at end of file
diff --git a/Minecraft.Server/Common/StringUtils.cpp b/Minecraft.Server/Common/StringUtils.cpp
index b22819f3d..82646eeb5 100644
--- a/Minecraft.Server/Common/StringUtils.cpp
+++ b/Minecraft.Server/Common/StringUtils.cpp
@@ -37,6 +37,7 @@ namespace ServerRuntime
 			int wideCount = MultiByteToWideChar(CP_UTF8, 0, value, -1, NULL, 0);
 			if (wideCount <= 0)
 			{
+				// Fall back to the current ANSI code page so legacy non-UTF-8 inputs remain readable.
 				wideCount = MultiByteToWideChar(CP_ACP, 0, value, -1, NULL, 0);
 				if (wideCount <= 0)
 				{
@@ -60,6 +61,19 @@ namespace ServerRuntime
 			return Utf8ToWide(value.c_str());
 		}
 
+		std::string StripUtf8Bom(const std::string &value)
+		{
+			if (value.size() >= 3 &&
+				(unsigned char)value[0] == 0xEF &&
+				(unsigned char)value[1] == 0xBB &&
+				(unsigned char)value[2] == 0xBF)
+			{
+				return value.substr(3);
+			}
+
+			return value;
+		}
+
 		std::string TrimAscii(const std::string &value)
 		{
 			size_t start = 0;
diff --git a/Minecraft.Server/Common/StringUtils.h b/Minecraft.Server/Common/StringUtils.h
index fa1d5734a..a2585b732 100644
--- a/Minecraft.Server/Common/StringUtils.h
+++ b/Minecraft.Server/Common/StringUtils.h
@@ -9,6 +9,7 @@ namespace ServerRuntime
 		std::string WideToUtf8(const std::wstring &value);
 		std::wstring Utf8ToWide(const char *value);
 		std::wstring Utf8ToWide(const std::string &value);
+		std::string StripUtf8Bom(const std::string &value);
 
 		std::string TrimAscii(const std::string &value);
 		std::string ToLowerAscii(const std::string &value);
diff --git a/Minecraft.Server/Minecraft.Server.vcxproj b/Minecraft.Server/Minecraft.Server.vcxproj
index 246da3068..a0a2e65c6 100644
--- a/Minecraft.Server/Minecraft.Server.vcxproj
+++ b/Minecraft.Server/Minecraft.Server.vcxproj
@@ -657,6 +657,7 @@
     <ClCompile Include="Console\ServerCliEngine.cpp" />
     <ClCompile Include="Console\ServerCliParser.cpp" />
     <ClCompile Include="Console\ServerCliRegistry.cpp" />
+    <ClCompile Include="Common\FileUtils.cpp" />
     <ClCompile Include="Common\StringUtils.cpp" />
     <ClCompile Include="..\Minecraft.Client\glWrapper.cpp" />
     <ClCompile Include="ServerLogger.cpp" />
@@ -684,6 +685,7 @@
     <ClInclude Include="Console\ServerCliEngine.h" />
     <ClInclude Include="Console\ServerCliParser.h" />
     <ClInclude Include="Console\ServerCliRegistry.h" />
+    <ClInclude Include="Common\FileUtils.h" />
     <ClInclude Include="Common\StringUtils.h" />
     <ClInclude Include="ServerLogger.h" />
     <ClInclude Include="ServerProperties.h" />
diff --git a/Minecraft.Server/Minecraft.Server.vcxproj.filters b/Minecraft.Server/Minecraft.Server.vcxproj.filters
index a4567a11f..3c8657e7b 100644
--- a/Minecraft.Server/Minecraft.Server.vcxproj.filters
+++ b/Minecraft.Server/Minecraft.Server.vcxproj.filters
@@ -48,6 +48,9 @@
     <ClCompile Include="Windows64\ServerMain.cpp">
       <Filter>Server</Filter>
     </ClCompile>
+    <ClCompile Include="Common\FileUtils.cpp">
+      <Filter>Server\Common</Filter>
+    </ClCompile>
     <ClCompile Include="..\Minecraft.Client\AbstractTexturePack.cpp" />
     <ClCompile Include="..\Minecraft.Client\AchievementPopup.cpp" />
     <ClCompile Include="..\Minecraft.Client\AchievementScreen.cpp" />
@@ -572,6 +575,9 @@
     <ClInclude Include="Console\ServerCliRegistry.h">
       <Filter>Server\Console</Filter>
     </ClInclude>
+    <ClInclude Include="Common\FileUtils.h">
+      <Filter>Server\Common</Filter>
+    </ClInclude>
     <ClInclude Include="Common\StringUtils.h">
       <Filter>Server\Common</Filter>
     </ClInclude>