diff --git a/AGENTS.md b/AGENTS.md
index 964a2e9d..027aed59 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -39,3 +39,14 @@ Additional policy:
 - Runtime test expectations use `TIME_SHIELD_TEST_CHECK(...)` from
   `tests/test_assert.hpp`; avoid `<cassert>` / `assert(...)` for tests because
   Release/NDEBUG builds can compile them out.
+
+Header guard rules:
+
+- For every project-owned C/C++ header, use `#pragma once` together with a
+  non-reserved include guard derived from the project prefix and header path:
+  `TIME_SHIELD_HEADER_<PATH>_<FILE>_<EXT>_INCLUDED`.
+- For MQL include files, use non-reserved guards derived from the project,
+  language, and path, for example
+  `TIME_SHIELD_MQL5_HEADER_<PATH>_<FILE>_<EXT>_INCLUDED`.
+- Do not use guard names that start with an underscore, start with an underscore
+  followed by an uppercase letter, or contain a double underscore.
diff --git a/MQL5/Include/time_shield/DateTime.mqh b/MQL5/Include/time_shield/DateTime.mqh
index d082b281..5f3bb51b 100644
--- a/MQL5/Include/time_shield/DateTime.mqh
+++ b/MQL5/Include/time_shield/DateTime.mqh
@@ -4,8 +4,8 @@
 //|                                      Copyright 2025, NewYaroslav |
 //|                   https://github.com/NewYaroslav/time-shield-cpp |
 //+------------------------------------------------------------------+
-#ifndef __TIME_SHIELD_DATE_TIME_MQH__
-#define __TIME_SHIELD_DATE_TIME_MQH__
+#ifndef TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_DATETIME_MQH_INCLUDED
+#define TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_DATETIME_MQH_INCLUDED
 
 /// \file DateTime.mqh
 /// \ingroup mql5
@@ -149,4 +149,4 @@ namespace time_shield {
 
 } // namespace time_shield
 
-#endif // __TIME_SHIELD_DATE_TIME_MQH__
+#endif // TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_DATETIME_MQH_INCLUDED
diff --git a/MQL5/Include/time_shield/constants.mqh b/MQL5/Include/time_shield/constants.mqh
index aa96955f..6d3d92f8 100644
--- a/MQL5/Include/time_shield/constants.mqh
+++ b/MQL5/Include/time_shield/constants.mqh
@@ -4,8 +4,8 @@
 //|                                      Copyright 2025, NewYaroslav |
 //|                   https://github.com/NewYaroslav/time-shield-cpp |
 //+------------------------------------------------------------------+
-#ifndef __TIME_SHIELD_CONSTANTS_MQH__
-#define __TIME_SHIELD_CONSTANTS_MQH__
+#ifndef TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_CONSTANTS_MQH_INCLUDED
+#define TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_CONSTANTS_MQH_INCLUDED
 
 /// \file constants.mqh
 /// \ingroup mql5
@@ -169,4 +169,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // __TIME_SHIELD_CONSTANTS_MQH__
+#endif // TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_CONSTANTS_MQH_INCLUDED
diff --git a/MQL5/Include/time_shield/date_struct.mqh b/MQL5/Include/time_shield/date_struct.mqh
index e699bb19..0f766521 100644
--- a/MQL5/Include/time_shield/date_struct.mqh
+++ b/MQL5/Include/time_shield/date_struct.mqh
@@ -4,8 +4,8 @@
 //|                                      Copyright 2025, NewYaroslav |
 //|                   https://github.com/NewYaroslav/time-shield-cpp |
 //+------------------------------------------------------------------+
-#ifndef __TIME_SHIELD_DATE_STRUCT_MQH__
-#define __TIME_SHIELD_DATE_STRUCT_MQH__
+#ifndef TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_DATE_STRUCT_MQH_INCLUDED
+#define TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_DATE_STRUCT_MQH_INCLUDED
 
 /// \file date_struct.mqh
 /// \ingroup mql5
@@ -44,4 +44,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // __TIME_SHIELD_DATE_STRUCT_MQH__
+#endif // TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_DATE_STRUCT_MQH_INCLUDED
diff --git a/MQL5/Include/time_shield/date_time_struct.mqh b/MQL5/Include/time_shield/date_time_struct.mqh
index e62941ef..c8b136d3 100644
--- a/MQL5/Include/time_shield/date_time_struct.mqh
+++ b/MQL5/Include/time_shield/date_time_struct.mqh
@@ -4,8 +4,8 @@
 //|                                      Copyright 2025, NewYaroslav |
 //|                   https://github.com/NewYaroslav/time-shield-cpp |
 //+------------------------------------------------------------------+
-#ifndef __TIME_SHIELD_DATE_TIME_STRUCT_MQH__
-#define __TIME_SHIELD_DATE_TIME_STRUCT_MQH__
+#ifndef TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_DATE_TIME_STRUCT_MQH_INCLUDED
+#define TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_DATE_TIME_STRUCT_MQH_INCLUDED
 
 /// \file date_time_struct.mqh
 /// \ingroup mql5
@@ -64,4 +64,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // __TIME_SHIELD_DATE_TIME_STRUCT_MQH__
+#endif // TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_DATE_TIME_STRUCT_MQH_INCLUDED
diff --git a/MQL5/Include/time_shield/enums.mqh b/MQL5/Include/time_shield/enums.mqh
index 3bc3ce2b..69e402b3 100644
--- a/MQL5/Include/time_shield/enums.mqh
+++ b/MQL5/Include/time_shield/enums.mqh
@@ -4,8 +4,8 @@
 //|                                      Copyright 2025, NewYaroslav |
 //|                   https://github.com/NewYaroslav/time-shield-cpp |
 //+------------------------------------------------------------------+
-#ifndef __TIME_SHIELD_ENUMS_MQH__
-#define __TIME_SHIELD_ENUMS_MQH__
+#ifndef TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_ENUMS_MQH_INCLUDED
+#define TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_ENUMS_MQH_INCLUDED
 
 /// \file enums.mqh
 /// \ingroup mql5
@@ -226,4 +226,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // __TIME_SHIELD_ENUMS_MQH__
+#endif // TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_ENUMS_MQH_INCLUDED
diff --git a/MQL5/Include/time_shield/initialization.mqh b/MQL5/Include/time_shield/initialization.mqh
index 8c248e9a..3fb106a0 100644
--- a/MQL5/Include/time_shield/initialization.mqh
+++ b/MQL5/Include/time_shield/initialization.mqh
@@ -4,8 +4,8 @@
 //|                                      Copyright 2025, NewYaroslav |
 //|                   https://github.com/NewYaroslav/time-shield-cpp |
 //+------------------------------------------------------------------+
-#ifndef __TIME_SHIELD_INITIALIZATION_MQH__
-#define __TIME_SHIELD_INITIALIZATION_MQH__
+#ifndef TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_INITIALIZATION_MQH_INCLUDED
+#define TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_INITIALIZATION_MQH_INCLUDED
 
 /// \file initialization.mqh
 /// \ingroup mql5
@@ -35,4 +35,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // __TIME_SHIELD_INITIALIZATION_MQH__
+#endif // TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_INITIALIZATION_MQH_INCLUDED
diff --git a/MQL5/Include/time_shield/time_conversions.mqh b/MQL5/Include/time_shield/time_conversions.mqh
index 0db59b90..36ab6e31 100644
--- a/MQL5/Include/time_shield/time_conversions.mqh
+++ b/MQL5/Include/time_shield/time_conversions.mqh
@@ -4,8 +4,8 @@
 //|                                      Copyright 2025, NewYaroslav |
 //|                   https://github.com/NewYaroslav/time-shield-cpp |
 //+------------------------------------------------------------------+
-#ifndef __TIME_SHIELD_TIME_CONVERSIONS_MQH__
-#define __TIME_SHIELD_TIME_CONVERSIONS_MQH__
+#ifndef TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_TIME_CONVERSIONS_MQH_INCLUDED
+#define TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_TIME_CONVERSIONS_MQH_INCLUDED
 
 /// \file time_conversions.mqh
 /// \ingroup mql5
@@ -1559,4 +1559,4 @@ double sec_to_fhour(long sec) {
 
 }; // namespace time_shield
 
-#endif // __TIME_SHIELD_TIME_CONVERSIONS_MQH__
+#endif // TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_TIME_CONVERSIONS_MQH_INCLUDED
diff --git a/MQL5/Include/time_shield/time_formatting.mqh b/MQL5/Include/time_shield/time_formatting.mqh
index b072b468..86a9ceee 100644
--- a/MQL5/Include/time_shield/time_formatting.mqh
+++ b/MQL5/Include/time_shield/time_formatting.mqh
@@ -4,8 +4,8 @@
 //|                                      Copyright 2025, NewYaroslav |
 //|                   https://github.com/NewYaroslav/time-shield-cpp |
 //+------------------------------------------------------------------+
-#ifndef __TIME_SHIELD_TIME_FORMATTING_MQH__
-#define __TIME_SHIELD_TIME_FORMATTING_MQH__
+#ifndef TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_TIME_FORMATTING_MQH_INCLUDED
+#define TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_TIME_FORMATTING_MQH_INCLUDED
 
 /// \file time_formatting.mqh
 /// \ingroup mql5
@@ -483,4 +483,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // __TIME_SHIELD_TIME_FORMATTING_MQH__
+#endif // TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_TIME_FORMATTING_MQH_INCLUDED
diff --git a/MQL5/Include/time_shield/time_parser.mqh b/MQL5/Include/time_shield/time_parser.mqh
index ebbc6786..e236b7c3 100644
--- a/MQL5/Include/time_shield/time_parser.mqh
+++ b/MQL5/Include/time_shield/time_parser.mqh
@@ -4,8 +4,8 @@
 //|                                      Copyright 2025, NewYaroslav |
 //|                   https://github.com/NewYaroslav/time-shield-cpp |
 //+------------------------------------------------------------------+
-#ifndef __TIME_SHIELD_TIME_PARSER_MQH__
-#define __TIME_SHIELD_TIME_PARSER_MQH__
+#ifndef TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_TIME_PARSER_MQH_INCLUDED
+#define TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_TIME_PARSER_MQH_INCLUDED
 
 /// \file time_parser.mqh
 /// \ingroup mql5
@@ -690,4 +690,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // __TIME_SHIELD_TIME_PARSER_MQH__
+#endif // TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_TIME_PARSER_MQH_INCLUDED
diff --git a/MQL5/Include/time_shield/time_struct.mqh b/MQL5/Include/time_shield/time_struct.mqh
index 830ddd10..6d0979ed 100644
--- a/MQL5/Include/time_shield/time_struct.mqh
+++ b/MQL5/Include/time_shield/time_struct.mqh
@@ -4,8 +4,8 @@
 //|                                      Copyright 2025, NewYaroslav |
 //|                   https://github.com/NewYaroslav/time-shield-cpp |
 //+------------------------------------------------------------------+
-#ifndef __TIME_SHIELD_TIME_STRUCT_MQH__
-#define __TIME_SHIELD_TIME_STRUCT_MQH__
+#ifndef TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_TIME_STRUCT_MQH_INCLUDED
+#define TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_TIME_STRUCT_MQH_INCLUDED
 
 /// \file time_struct.mqh
 /// \ingroup mql5
@@ -52,4 +52,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // __TIME_SHIELD_TIME_STRUCT_MQH__
+#endif // TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_TIME_STRUCT_MQH_INCLUDED
diff --git a/MQL5/Include/time_shield/time_utils.mqh b/MQL5/Include/time_shield/time_utils.mqh
index 62773165..6458a55a 100644
--- a/MQL5/Include/time_shield/time_utils.mqh
+++ b/MQL5/Include/time_shield/time_utils.mqh
@@ -4,8 +4,8 @@
 //|                                      Copyright 2025, NewYaroslav |
 //|                   https://github.com/NewYaroslav/time-shield-cpp |
 //+------------------------------------------------------------------+
-#ifndef __TIME_SHIELD_TIME_UTILS_MQH__
-#define __TIME_SHIELD_TIME_UTILS_MQH__
+#ifndef TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_TIME_UTILS_MQH_INCLUDED
+#define TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_TIME_UTILS_MQH_INCLUDED
 
 /// \file time_utils.mqh
 /// \ingroup mql5
@@ -112,4 +112,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // __TIME_SHIELD_TIME_UTILS_MQH__
+#endif // TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_TIME_UTILS_MQH_INCLUDED
diff --git a/MQL5/Include/time_shield/time_zone_conversions.mqh b/MQL5/Include/time_shield/time_zone_conversions.mqh
index 7cd81224..8b4fc534 100644
--- a/MQL5/Include/time_shield/time_zone_conversions.mqh
+++ b/MQL5/Include/time_shield/time_zone_conversions.mqh
@@ -4,8 +4,8 @@
 //|                                      Copyright 2025, NewYaroslav |
 //|                   https://github.com/NewYaroslav/time-shield-cpp |
 //+------------------------------------------------------------------+
-#ifndef __TIME_SHIELD_TIME_ZONE_CONVERSIONS_MQH__
-#define __TIME_SHIELD_TIME_ZONE_CONVERSIONS_MQH__
+#ifndef TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_TIME_ZONE_CONVERSIONS_MQH_INCLUDED
+#define TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_TIME_ZONE_CONVERSIONS_MQH_INCLUDED
 
 /// \file time_zone_conversions.mqh
 /// \ingroup mql5
@@ -445,4 +445,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // __TIME_SHIELD_TIME_ZONE_CONVERSIONS_MQH__
+#endif // TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_TIME_ZONE_CONVERSIONS_MQH_INCLUDED
diff --git a/MQL5/Include/time_shield/time_zone_struct.mqh b/MQL5/Include/time_shield/time_zone_struct.mqh
index c238893d..be61e8f8 100644
--- a/MQL5/Include/time_shield/time_zone_struct.mqh
+++ b/MQL5/Include/time_shield/time_zone_struct.mqh
@@ -4,8 +4,8 @@
 //|                                      Copyright 2025, NewYaroslav |
 //|                   https://github.com/NewYaroslav/time-shield-cpp |
 //+------------------------------------------------------------------+
-#ifndef __TIME_SHIELD_TIME_ZONE_STRUCT_MQH__
-#define __TIME_SHIELD_TIME_ZONE_STRUCT_MQH__
+#ifndef TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_TIME_ZONE_STRUCT_MQH_INCLUDED
+#define TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_TIME_ZONE_STRUCT_MQH_INCLUDED
 
 /// \file time_zone_struct.mqh
 /// \ingroup mql5
@@ -138,4 +138,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // __TIME_SHIELD_TIME_ZONE_STRUCT_MQH__
+#endif // TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_TIME_ZONE_STRUCT_MQH_INCLUDED
diff --git a/MQL5/Include/time_shield/validation.mqh b/MQL5/Include/time_shield/validation.mqh
index d454d49b..0e7453a4 100644
--- a/MQL5/Include/time_shield/validation.mqh
+++ b/MQL5/Include/time_shield/validation.mqh
@@ -4,8 +4,8 @@
 //|                                      Copyright 2025, NewYaroslav |
 //|                   https://github.com/NewYaroslav/time-shield-cpp |
 //+------------------------------------------------------------------+
-#ifndef __TIME_SHIELD_VALIDATION_MQH__
-#define __TIME_SHIELD_VALIDATION_MQH__
+#ifndef TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_VALIDATION_MQH_INCLUDED
+#define TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_VALIDATION_MQH_INCLUDED
 
 /// \file validation.mqh
 /// \ingroup mql5
@@ -303,4 +303,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // __TIME_SHIELD_VALIDATION_MQH__
+#endif // TIME_SHIELD_MQL5_HEADER_TIME_SHIELD_VALIDATION_MQH_INCLUDED
diff --git a/agents/cpp-development-guidelines.md b/agents/cpp-development-guidelines.md
index 0cac7689..302f0bef 100644
--- a/agents/cpp-development-guidelines.md
+++ b/agents/cpp-development-guidelines.md
@@ -51,7 +51,14 @@
 - Keep opening braces on the same line for classes, methods, and namespaces.
 - Do not use `using namespace`; always qualify names (for example `std::`).
 - Keep project headers before system headers in include lists.
-- Header files must start with `#pragma once`; if an include guard is additionally used, prefer `_MGC_PLATFORM_*_HPP_INCLUDED`.
+- Header files must start with `#pragma once` and a non-reserved include guard
+  derived from the project prefix and header path:
+  `TIME_SHIELD_HEADER_<PATH>_<FILE>_<EXT>_INCLUDED`.
+- MQL include files use non-reserved guards derived from the project, language,
+  and path, for example
+  `TIME_SHIELD_MQL5_HEADER_<PATH>_<FILE>_<EXT>_INCLUDED`.
+- Do not use guard names that start with an underscore, start with an
+  underscore followed by an uppercase letter, or contain a double underscore.
 
 ## Header / Implementation ownership
 
diff --git a/include/time_shield.hpp b/include/time_shield.hpp
index 74bd5f23..64f0fec1 100644
--- a/include/time_shield.hpp
+++ b/include/time_shield.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_HPP_INCLUDED
-#define _TIME_SHIELD_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_HPP_INCLUDED
 
 /// \file time_shield.hpp
 /// \brief Main header file for the Time Shield library.
@@ -62,4 +62,4 @@ namespace tshield = time_shield;
 /// - timers and scheduling utilities
 namespace time_shield {};
 
-#endif // _TIME_SHIELD_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_HPP_INCLUDED
diff --git a/include/time_shield/CpuTickTimer.hpp b/include/time_shield/CpuTickTimer.hpp
index 4eef221f..0c00ed24 100644
--- a/include/time_shield/CpuTickTimer.hpp
+++ b/include/time_shield/CpuTickTimer.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_CPU_TICK_TIMER_HPP_INCLUDED
-#define _TIME_SHIELD_CPU_TICK_TIMER_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_CPUTICKTIMER_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_CPUTICKTIMER_HPP_INCLUDED
 
 /// \file CpuTickTimer.hpp
 /// \brief Helper class for measuring CPU time using get_cpu_time().
@@ -134,4 +134,4 @@ namespace time_shield {
 
 } // namespace time_shield
 
-#endif // _TIME_SHIELD_CPU_TICK_TIMER_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_CPUTICKTIMER_HPP_INCLUDED
diff --git a/include/time_shield/DateTime.hpp b/include/time_shield/DateTime.hpp
index f1123748..a51265b7 100644
--- a/include/time_shield/DateTime.hpp
+++ b/include/time_shield/DateTime.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_DATE_TIME_HPP_INCLUDED
-#define _TIME_SHIELD_DATE_TIME_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_DATETIME_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_DATETIME_HPP_INCLUDED
 
 /// \file DateTime.hpp
 /// \brief Value-type wrapper for timestamps with fixed UTC offset.
@@ -711,4 +711,4 @@ namespace time_shield {
 
 } // namespace time_shield
 
-#endif // _TIME_SHIELD_DATE_TIME_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_DATETIME_HPP_INCLUDED
diff --git a/include/time_shield/DeadlineTimer.hpp b/include/time_shield/DeadlineTimer.hpp
index 4e68ad41..57aea3a1 100644
--- a/include/time_shield/DeadlineTimer.hpp
+++ b/include/time_shield/DeadlineTimer.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_DEADLINE_TIMER_HPP_INCLUDED
-#define _TIME_SHIELD_DEADLINE_TIMER_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_DEADLINETIMER_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_DEADLINETIMER_HPP_INCLUDED
 
 /// \file DeadlineTimer.hpp
 /// \brief Monotonic deadline timer utility similar to Qt's QDeadlineTimer.
@@ -241,4 +241,4 @@ namespace time_shield {
 
 } // namespace time_shield
 
-#endif // _TIME_SHIELD_DEADLINE_TIMER_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_DEADLINETIMER_HPP_INCLUDED
diff --git a/include/time_shield/ElapsedTimer.hpp b/include/time_shield/ElapsedTimer.hpp
index 3c954e0f..14ff0094 100644
--- a/include/time_shield/ElapsedTimer.hpp
+++ b/include/time_shield/ElapsedTimer.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_ELAPSED_TIMER_HPP_INCLUDED
-#define _TIME_SHIELD_ELAPSED_TIMER_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_ELAPSEDTIMER_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_ELAPSEDTIMER_HPP_INCLUDED
 
 /// \file ElapsedTimer.hpp
 /// \brief High-precision elapsed time measurement helper similar to Qt's QElapsedTimer.
@@ -185,4 +185,4 @@ namespace time_shield {
 
 } // namespace time_shield
 
-#endif // _TIME_SHIELD_ELAPSED_TIMER_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_ELAPSEDTIMER_HPP_INCLUDED
diff --git a/include/time_shield/MoonPhase.hpp b/include/time_shield/MoonPhase.hpp
index 2950d959..0f7de3ed 100644
--- a/include/time_shield/MoonPhase.hpp
+++ b/include/time_shield/MoonPhase.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_MOON_PHASE_HPP_INCLUDED
-#define _TIME_SHIELD_MOON_PHASE_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_MOONPHASE_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_MOONPHASE_HPP_INCLUDED
 
 /// \file MoonPhase.hpp
 /// \brief Geocentric Moon phase calculator and result helpers.
@@ -400,4 +400,4 @@ namespace astronomy {
 
 } // namespace time_shield
 
-#endif // _TIME_SHIELD_MOON_PHASE_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_MOONPHASE_HPP_INCLUDED
diff --git a/include/time_shield/TimerScheduler.hpp b/include/time_shield/TimerScheduler.hpp
index 1ad79d94..7de06754 100644
--- a/include/time_shield/TimerScheduler.hpp
+++ b/include/time_shield/TimerScheduler.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_TIMER_SCHEDULER_HPP_INCLUDED
-#define _TIME_SHIELD_TIMER_SCHEDULER_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_TIMERSCHEDULER_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_TIMERSCHEDULER_HPP_INCLUDED
 
 /// \file TimerScheduler.hpp
 /// \brief Timer scheduler that provides Qt-like timer functionality.
@@ -647,4 +647,4 @@ namespace time_shield {
 
 } // namespace time_shield
 
-#endif // _TIME_SHIELD_TIMER_SCHEDULER_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_TIMERSCHEDULER_HPP_INCLUDED
diff --git a/include/time_shield/ZonedClock.hpp b/include/time_shield/ZonedClock.hpp
index b262dbc3..4c292712 100644
--- a/include/time_shield/ZonedClock.hpp
+++ b/include/time_shield/ZonedClock.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_ZONED_CLOCK_HPP_INCLUDED
-#define _TIME_SHIELD_ZONED_CLOCK_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_ZONEDCLOCK_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_ZONEDCLOCK_HPP_INCLUDED
 
 /// \file ZonedClock.hpp
 /// \brief Header-only clock wrapper for named zones, fixed offsets, and optional NTP-backed UTC time.
@@ -369,4 +369,4 @@ namespace time_shield {
 
 } // namespace time_shield
 
-#endif // _TIME_SHIELD_ZONED_CLOCK_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_ZONEDCLOCK_HPP_INCLUDED
diff --git a/include/time_shield/astronomy_conversions.hpp b/include/time_shield/astronomy_conversions.hpp
index 8f9fed80..bdef4367 100644
--- a/include/time_shield/astronomy_conversions.hpp
+++ b/include/time_shield/astronomy_conversions.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_ASTRONOMY_CONVERSIONS_HPP_INCLUDED
-#define _TIME_SHIELD_ASTRONOMY_CONVERSIONS_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_ASTRONOMY_CONVERSIONS_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_ASTRONOMY_CONVERSIONS_HPP_INCLUDED
 
 /// \file astronomy_conversions.hpp
 /// \brief Astronomy entry header with Julian conversions and lunar helpers.
@@ -115,4 +115,4 @@ namespace time_shield {
 
 } // namespace time_shield
 
-#endif // _TIME_SHIELD_ASTRONOMY_CONVERSIONS_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_ASTRONOMY_CONVERSIONS_HPP_INCLUDED
diff --git a/include/time_shield/config.hpp b/include/time_shield/config.hpp
index 12f6f610..8c10b59b 100644
--- a/include/time_shield/config.hpp
+++ b/include/time_shield/config.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_CONFIG_HPP_INCLUDED
-#define _TIME_SHIELD_CONFIG_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_CONFIG_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_CONFIG_HPP_INCLUDED
 
 /// \file config.hpp
 /// \brief Configuration macros for the library.
@@ -116,4 +116,4 @@
 #endif
 ///@}
 
-#endif // _TIME_SHIELD_CONFIG_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_CONFIG_HPP_INCLUDED
diff --git a/include/time_shield/constants.hpp b/include/time_shield/constants.hpp
index d38d897f..b87ec308 100644
--- a/include/time_shield/constants.hpp
+++ b/include/time_shield/constants.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_CONSTANTS_HPP_INCLUDED
-#define _TIME_SHIELD_CONSTANTS_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_CONSTANTS_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_CONSTANTS_HPP_INCLUDED
 
 /// \file constants.hpp
 /// \brief Header file with time-related constants.
@@ -166,4 +166,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // _TIME_SHIELD_CONSTANTS_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_CONSTANTS_HPP_INCLUDED
diff --git a/include/time_shield/date_conversions.hpp b/include/time_shield/date_conversions.hpp
index cbba4f9b..397bc57b 100644
--- a/include/time_shield/date_conversions.hpp
+++ b/include/time_shield/date_conversions.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_DATE_CONVERSIONS_HPP_INCLUDED
-#define _TIME_SHIELD_DATE_CONVERSIONS_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_DATE_CONVERSIONS_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_DATE_CONVERSIONS_HPP_INCLUDED
 
 /// \file date_conversions.hpp
 /// \brief Conversions related to calendar dates and DateStruct helpers.
@@ -109,4 +109,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // _TIME_SHIELD_DATE_CONVERSIONS_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_DATE_CONVERSIONS_HPP_INCLUDED
diff --git a/include/time_shield/date_struct.hpp b/include/time_shield/date_struct.hpp
index ce854104..b88db0ca 100644
--- a/include/time_shield/date_struct.hpp
+++ b/include/time_shield/date_struct.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_DATE_STRUCT_HPP_INCLUDED
-#define _TIME_SHIELD_DATE_STRUCT_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_DATE_STRUCT_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_DATE_STRUCT_HPP_INCLUDED
 
 /// \file date_struct.hpp
 /// \brief Header for date structure and related functions.
@@ -34,4 +34,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // _TIME_SHIELD_DATE_STRUCT_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_DATE_STRUCT_HPP_INCLUDED
diff --git a/include/time_shield/date_time_conversions.hpp b/include/time_shield/date_time_conversions.hpp
index 35a3cfe9..0a4f9681 100644
--- a/include/time_shield/date_time_conversions.hpp
+++ b/include/time_shield/date_time_conversions.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_DATE_TIME_CONVERSIONS_HPP_INCLUDED
-#define _TIME_SHIELD_DATE_TIME_CONVERSIONS_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_DATE_TIME_CONVERSIONS_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_DATE_TIME_CONVERSIONS_HPP_INCLUDED
 
 /// \file date_time_conversions.hpp
 /// \brief Conversions involving DateTimeStruct and day boundary helpers.
@@ -1214,4 +1214,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // _TIME_SHIELD_DATE_TIME_CONVERSIONS_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_DATE_TIME_CONVERSIONS_HPP_INCLUDED
diff --git a/include/time_shield/date_time_struct.hpp b/include/time_shield/date_time_struct.hpp
index 71b68d12..539246db 100644
--- a/include/time_shield/date_time_struct.hpp
+++ b/include/time_shield/date_time_struct.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_DATE_TIME_STRUCT_HPP_INCLUDED
-#define _TIME_SHIELD_DATE_TIME_STRUCT_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_DATE_TIME_STRUCT_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_DATE_TIME_STRUCT_HPP_INCLUDED
 
 /// \file date_time_struct.hpp
 /// \brief Header for date and time structure and related functions.
@@ -55,4 +55,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // _TIME_SHIELD_DATE_TIME_STRUCT_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_DATE_TIME_STRUCT_HPP_INCLUDED
diff --git a/include/time_shield/detail/fast_date.hpp b/include/time_shield/detail/fast_date.hpp
index 6563b657..537ce74e 100644
--- a/include/time_shield/detail/fast_date.hpp
+++ b/include/time_shield/detail/fast_date.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_DETAIL_FAST_DATE_HPP_INCLUDED
-#define _TIME_SHIELD_DETAIL_FAST_DATE_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_DETAIL_FAST_DATE_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_DETAIL_FAST_DATE_HPP_INCLUDED
 
 /// \file fast_date.hpp
 /// \brief Fast date conversion helpers.
@@ -242,4 +242,4 @@ namespace detail {
 } // namespace detail
 } // namespace time_shield
 
-#endif // _TIME_SHIELD_DETAIL_FAST_DATE_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_DETAIL_FAST_DATE_HPP_INCLUDED
diff --git a/include/time_shield/detail/floor_math.hpp b/include/time_shield/detail/floor_math.hpp
index 5401a829..0fa93df9 100644
--- a/include/time_shield/detail/floor_math.hpp
+++ b/include/time_shield/detail/floor_math.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_DETAIL_FLOOR_MATH_HPP_INCLUDED
-#define _TIME_SHIELD_DETAIL_FLOOR_MATH_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_DETAIL_FLOOR_MATH_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_DETAIL_FLOOR_MATH_HPP_INCLUDED
 
 /// \file floor_math.hpp
 /// \brief Floor division and modulus helpers.
@@ -24,4 +24,4 @@ namespace detail {
 } // namespace detail
 } // namespace time_shield
 
-#endif // _TIME_SHIELD_DETAIL_FLOOR_MATH_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_DETAIL_FLOOR_MATH_HPP_INCLUDED
diff --git a/include/time_shield/detail/mul_hi.hpp b/include/time_shield/detail/mul_hi.hpp
index f1d80bd5..c13b9dd7 100644
--- a/include/time_shield/detail/mul_hi.hpp
+++ b/include/time_shield/detail/mul_hi.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_DETAIL_MUL_HI_HPP_INCLUDED
-#define _TIME_SHIELD_DETAIL_MUL_HI_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_DETAIL_MUL_HI_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_DETAIL_MUL_HI_HPP_INCLUDED
 
 /// \file mul_hi.hpp
 /// \brief Helpers for 64-bit multiply-high operations.
@@ -56,4 +56,4 @@ namespace detail {
 } // namespace detail
 } // namespace time_shield
 
-#endif // _TIME_SHIELD_DETAIL_MUL_HI_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_DETAIL_MUL_HI_HPP_INCLUDED
diff --git a/include/time_shield/enums.hpp b/include/time_shield/enums.hpp
index 385e852b..43cd4b56 100644
--- a/include/time_shield/enums.hpp
+++ b/include/time_shield/enums.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_ENUMS_HPP_INCLUDED
-#define _TIME_SHIELD_ENUMS_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_ENUMS_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_ENUMS_HPP_INCLUDED
 
 /// \file enums.hpp
 /// \ingroup time_enums
@@ -309,4 +309,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // _TIME_SHIELD_ENUMS_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_ENUMS_HPP_INCLUDED
diff --git a/include/time_shield/initialization.hpp b/include/time_shield/initialization.hpp
index eb938460..3d15f650 100644
--- a/include/time_shield/initialization.hpp
+++ b/include/time_shield/initialization.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_INITIALIZATION_HPP_INCLUDED
-#define _TIME_SHIELD_INITIALIZATION_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_INITIALIZATION_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_INITIALIZATION_HPP_INCLUDED
 
 /// \file initialization.hpp
 /// \ingroup lib_initialization
@@ -26,4 +26,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // _TIME_SHIELD_INITIALIZATION_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_INITIALIZATION_HPP_INCLUDED
diff --git a/include/time_shield/iso_week_conversions.hpp b/include/time_shield/iso_week_conversions.hpp
index 5b3b547c..8fa830bd 100644
--- a/include/time_shield/iso_week_conversions.hpp
+++ b/include/time_shield/iso_week_conversions.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_ISO_WEEK_CONVERSIONS_HPP_INCLUDED
-#define _TIME_SHIELD_ISO_WEEK_CONVERSIONS_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_ISO_WEEK_CONVERSIONS_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_ISO_WEEK_CONVERSIONS_HPP_INCLUDED
 
 /// \file iso_week_conversions.hpp
 /// \brief Conversions and utilities for ISO week dates (ISO 8601).
@@ -263,4 +263,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // _TIME_SHIELD_ISO_WEEK_CONVERSIONS_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_ISO_WEEK_CONVERSIONS_HPP_INCLUDED
diff --git a/include/time_shield/iso_week_struct.hpp b/include/time_shield/iso_week_struct.hpp
index 58f4754f..0c61cd6c 100644
--- a/include/time_shield/iso_week_struct.hpp
+++ b/include/time_shield/iso_week_struct.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_ISO_WEEK_STRUCT_HPP_INCLUDED
-#define _TIME_SHIELD_ISO_WEEK_STRUCT_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_ISO_WEEK_STRUCT_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_ISO_WEEK_STRUCT_HPP_INCLUDED
 
 /// \file iso_week_struct.hpp
 /// \brief Header for ISO week date structure.
@@ -36,4 +36,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // _TIME_SHIELD_ISO_WEEK_STRUCT_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_ISO_WEEK_STRUCT_HPP_INCLUDED
diff --git a/include/time_shield/julian_conversions.hpp b/include/time_shield/julian_conversions.hpp
index 26c5de57..1bf053e7 100644
--- a/include/time_shield/julian_conversions.hpp
+++ b/include/time_shield/julian_conversions.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_JULIAN_CONVERSIONS_HPP_INCLUDED
-#define _TIME_SHIELD_JULIAN_CONVERSIONS_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_JULIAN_CONVERSIONS_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_JULIAN_CONVERSIONS_HPP_INCLUDED
 
 /// \file julian_conversions.hpp
 /// \brief Julian Date / MJD / JDN helpers using the proleptic Gregorian calendar.
@@ -240,4 +240,4 @@ namespace time_shield {
 
 } // namespace time_shield
 
-#endif // _TIME_SHIELD_JULIAN_CONVERSIONS_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_JULIAN_CONVERSIONS_HPP_INCLUDED
diff --git a/include/time_shield/ntp_client.hpp b/include/time_shield/ntp_client.hpp
index d0e9b3dd..398354fd 100644
--- a/include/time_shield/ntp_client.hpp
+++ b/include/time_shield/ntp_client.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_NTP_CLIENT_HPP_INCLUDED
-#define _TIME_SHIELD_NTP_CLIENT_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_HPP_INCLUDED
 
 /// \file ntp_client.hpp
 /// \brief Simple NTP client for querying time offset from NTP servers.
@@ -177,4 +177,4 @@ namespace time_shield {
 
 #endif // TIME_SHIELD_ENABLE_NTP_CLIENT
 
-#endif // _TIME_SHIELD_NTP_CLIENT_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_HPP_INCLUDED
diff --git a/include/time_shield/ntp_client/ntp_client_core.hpp b/include/time_shield/ntp_client/ntp_client_core.hpp
index 3cfc3939..53270e5d 100644
--- a/include/time_shield/ntp_client/ntp_client_core.hpp
+++ b/include/time_shield/ntp_client/ntp_client_core.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_NTP_CLIENT_CORE_HPP_INCLUDED
-#define _TIME_SHIELD_NTP_CLIENT_CORE_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_NTP_CLIENT_CORE_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_NTP_CLIENT_CORE_HPP_INCLUDED
 
 #include "ntp_packet.hpp"
 #include "udp_transport.hpp"
@@ -84,4 +84,4 @@ namespace detail {
 } // namespace detail
 } // namespace time_shield
 
-#endif // _TIME_SHIELD_NTP_CLIENT_CORE_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_NTP_CLIENT_CORE_HPP_INCLUDED
diff --git a/include/time_shield/ntp_client/ntp_packet.hpp b/include/time_shield/ntp_client/ntp_packet.hpp
index 7cb3981d..ec19b72e 100644
--- a/include/time_shield/ntp_client/ntp_packet.hpp
+++ b/include/time_shield/ntp_client/ntp_packet.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_NTP_PACKET_HPP_INCLUDED
-#define _TIME_SHIELD_NTP_PACKET_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_NTP_PACKET_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_NTP_PACKET_HPP_INCLUDED
 
 #include <cstdint>
 #include <cstring>
@@ -163,4 +163,4 @@ namespace detail {
 } // namespace detail
 } // namespace time_shield
 
-#endif // _TIME_SHIELD_NTP_PACKET_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_NTP_PACKET_HPP_INCLUDED
diff --git a/include/time_shield/ntp_client/udp_transport.hpp b/include/time_shield/ntp_client/udp_transport.hpp
index 9661f1bd..ec588cff 100644
--- a/include/time_shield/ntp_client/udp_transport.hpp
+++ b/include/time_shield/ntp_client/udp_transport.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_UDP_TRANSPORT_HPP_INCLUDED
-#define _TIME_SHIELD_UDP_TRANSPORT_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_UDP_TRANSPORT_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_UDP_TRANSPORT_HPP_INCLUDED
 
 #include <cstddef>
 #include <string>
@@ -32,4 +32,4 @@ namespace detail {
 } // namespace detail
 } // namespace time_shield
 
-#endif // _TIME_SHIELD_UDP_TRANSPORT_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_UDP_TRANSPORT_HPP_INCLUDED
diff --git a/include/time_shield/ntp_client/udp_transport_posix.hpp b/include/time_shield/ntp_client/udp_transport_posix.hpp
index 0dbff1de..945e4e5b 100644
--- a/include/time_shield/ntp_client/udp_transport_posix.hpp
+++ b/include/time_shield/ntp_client/udp_transport_posix.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_UDP_TRANSPORT_POSIX_HPP_INCLUDED
-#define _TIME_SHIELD_UDP_TRANSPORT_POSIX_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_UDP_TRANSPORT_POSIX_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_UDP_TRANSPORT_POSIX_HPP_INCLUDED
 
 #if TIME_SHIELD_PLATFORM_UNIX
 
@@ -92,4 +92,4 @@ namespace detail {
 
 #endif // _TIME_SHIELD_PLATFORM_UNIX
 
-#endif // _TIME_SHIELD_UDP_TRANSPORT_POSIX_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_UDP_TRANSPORT_POSIX_HPP_INCLUDED
diff --git a/include/time_shield/ntp_client/udp_transport_win.hpp b/include/time_shield/ntp_client/udp_transport_win.hpp
index f597ef6b..90ba07e3 100644
--- a/include/time_shield/ntp_client/udp_transport_win.hpp
+++ b/include/time_shield/ntp_client/udp_transport_win.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_UDP_TRANSPORT_WIN_HPP_INCLUDED
-#define _TIME_SHIELD_UDP_TRANSPORT_WIN_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_UDP_TRANSPORT_WIN_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_UDP_TRANSPORT_WIN_HPP_INCLUDED
 
 #if TIME_SHIELD_PLATFORM_WINDOWS
 
@@ -92,4 +92,4 @@ namespace detail {
 
 #endif // _TIME_SHIELD_PLATFORM_WINDOWS
 
-#endif // _TIME_SHIELD_UDP_TRANSPORT_WIN_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_UDP_TRANSPORT_WIN_HPP_INCLUDED
diff --git a/include/time_shield/ntp_client/wsa_guard.hpp b/include/time_shield/ntp_client/wsa_guard.hpp
index 7f5987c3..cc3b2406 100644
--- a/include/time_shield/ntp_client/wsa_guard.hpp
+++ b/include/time_shield/ntp_client/wsa_guard.hpp
@@ -1,6 +1,7 @@
+// SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_WSA_GUARD_HPP_INCLUDED
-#define _TIME_SHIELD_WSA_GUARD_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_WSA_GUARD_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_WSA_GUARD_HPP_INCLUDED
 
 /// \file wsa_guard.hpp
 /// \brief Singleton guard for WinSock initialization.
@@ -65,5 +66,4 @@ namespace time_shield {
 
 } // namespace time_shield
 
-#endif // _TIME_SHIELD_WSA_GUARD_HPP_INCLUDED
-
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_WSA_GUARD_HPP_INCLUDED
diff --git a/include/time_shield/ntp_client_pool.hpp b/include/time_shield/ntp_client_pool.hpp
index 157eb7b9..3d2917c2 100644
--- a/include/time_shield/ntp_client_pool.hpp
+++ b/include/time_shield/ntp_client_pool.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_NTP_CLIENT_POOL_HPP_INCLUDED
-#define _TIME_SHIELD_NTP_CLIENT_POOL_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_POOL_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_POOL_HPP_INCLUDED
 
 #include "config.hpp"
 
@@ -730,4 +730,4 @@ namespace time_shield {
 
 #endif // TIME_SHIELD_ENABLE_NTP_CLIENT
 
-#endif // _TIME_SHIELD_NTP_CLIENT_POOL_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_POOL_HPP_INCLUDED
diff --git a/include/time_shield/ntp_client_pool_runner.hpp b/include/time_shield/ntp_client_pool_runner.hpp
index 89063530..fcc964c5 100644
--- a/include/time_shield/ntp_client_pool_runner.hpp
+++ b/include/time_shield/ntp_client_pool_runner.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_NTP_CLIENT_POOL_RUNNER_HPP_INCLUDED
-#define _TIME_SHIELD_NTP_CLIENT_POOL_RUNNER_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_POOL_RUNNER_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_POOL_RUNNER_HPP_INCLUDED
 
 #include "config.hpp"
 
@@ -231,4 +231,4 @@ namespace time_shield {
 
 #endif // _TIME_SHIELD_ENABLE_NTP_CLIENT
 
-#endif // _TIME_SHIELD_NTP_CLIENT_POOL_RUNNER_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_NTP_CLIENT_POOL_RUNNER_HPP_INCLUDED
diff --git a/include/time_shield/ntp_time_service.hpp b/include/time_shield/ntp_time_service.hpp
index 271a577b..4c0db67d 100644
--- a/include/time_shield/ntp_time_service.hpp
+++ b/include/time_shield/ntp_time_service.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_NTP_TIME_SERVICE_HPP_INCLUDED
-#define _TIME_SHIELD_NTP_TIME_SERVICE_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_NTP_TIME_SERVICE_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_NTP_TIME_SERVICE_HPP_INCLUDED
 
 #include "config.hpp"
 
@@ -892,4 +892,4 @@ namespace time_shield {
 
 #endif // _TIME_SHIELD_ENABLE_NTP_CLIENT
 
-#endif // _TIME_SHIELD_NTP_TIME_SERVICE_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_NTP_TIME_SERVICE_HPP_INCLUDED
diff --git a/include/time_shield/ole_automation_conversions.hpp b/include/time_shield/ole_automation_conversions.hpp
index 1f066b1d..5e4c05d6 100644
--- a/include/time_shield/ole_automation_conversions.hpp
+++ b/include/time_shield/ole_automation_conversions.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_OLE_AUTOMATION_CONVERSIONS_HPP_INCLUDED
-#define _TIME_SHIELD_OLE_AUTOMATION_CONVERSIONS_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_OLE_AUTOMATION_CONVERSIONS_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_OLE_AUTOMATION_CONVERSIONS_HPP_INCLUDED
 
 /// \file ole_automation_conversions.hpp
 /// \brief OLE Automation Date (OA date) conversions.
@@ -156,4 +156,4 @@ namespace time_shield {
 
 } // namespace time_shield
 
-#endif // _TIME_SHIELD_OLE_AUTOMATION_CONVERSIONS_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_OLE_AUTOMATION_CONVERSIONS_HPP_INCLUDED
diff --git a/include/time_shield/time_conversion_aliases.hpp b/include/time_shield/time_conversion_aliases.hpp
index efbeb254..367227a7 100644
--- a/include/time_shield/time_conversion_aliases.hpp
+++ b/include/time_shield/time_conversion_aliases.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_TIME_CONVERSIONS_ALIASES_HPP_INCLUDED
-#define _TIME_SHIELD_TIME_CONVERSIONS_ALIASES_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_TIME_CONVERSION_ALIASES_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_TIME_CONVERSION_ALIASES_HPP_INCLUDED
 
 /// \file time_conversion_aliases.hpp
 /// \brief Doxygen-only stubs for alias functions defined via macros.
@@ -2184,4 +2184,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // _TIME_SHIELD_TIME_CONVERSIONS_ALIASES_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_TIME_CONVERSION_ALIASES_HPP_INCLUDED
diff --git a/include/time_shield/time_conversions.hpp b/include/time_shield/time_conversions.hpp
index 5c60570d..9f1bf818 100644
--- a/include/time_shield/time_conversions.hpp
+++ b/include/time_shield/time_conversions.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_TIME_CONVERSIONS_HPP_INCLUDED
-#define _TIME_SHIELD_TIME_CONVERSIONS_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_TIME_CONVERSIONS_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_TIME_CONVERSIONS_HPP_INCLUDED
 
 /// \file time_conversions.hpp
 /// \brief Umbrella header for time conversion functions.
@@ -26,4 +26,4 @@
 #include "astronomy_conversions.hpp"
 #include "time_conversion_aliases.hpp"
 
-#endif // _TIME_SHIELD_TIME_CONVERSIONS_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_TIME_CONVERSIONS_HPP_INCLUDED
diff --git a/include/time_shield/time_format_parser.hpp b/include/time_shield/time_format_parser.hpp
index 25dcbde0..cfaaab9b 100644
--- a/include/time_shield/time_format_parser.hpp
+++ b/include/time_shield/time_format_parser.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_TIME_FORMAT_PARSER_HPP_INCLUDED
-#define _TIME_SHIELD_TIME_FORMAT_PARSER_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_TIME_FORMAT_PARSER_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_TIME_FORMAT_PARSER_HPP_INCLUDED
 
 /// \file time_format_parser.hpp
 /// \brief Header file for fast parsing with formatter-compatible custom patterns.
@@ -1161,4 +1161,4 @@ namespace time_shield {
 
 } // namespace time_shield
 
-#endif // _TIME_SHIELD_TIME_FORMAT_PARSER_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_TIME_FORMAT_PARSER_HPP_INCLUDED
diff --git a/include/time_shield/time_formatting.hpp b/include/time_shield/time_formatting.hpp
index e4375e8a..86b63f2f 100644
--- a/include/time_shield/time_formatting.hpp
+++ b/include/time_shield/time_formatting.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_TIME_FORMATTING_HPP_INCLUDED
-#define _TIME_SHIELD_TIME_FORMATTING_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_TIME_FORMATTING_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_TIME_FORMATTING_HPP_INCLUDED
 
 /// \file time_formatting.hpp
 /// \brief Header file for time formatting utilities.
@@ -1006,4 +1006,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // _TIME_SHIELD_TIME_FORMATTING_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_TIME_FORMATTING_HPP_INCLUDED
diff --git a/include/time_shield/time_parser.hpp b/include/time_shield/time_parser.hpp
index cf154404..f1d875b2 100644
--- a/include/time_shield/time_parser.hpp
+++ b/include/time_shield/time_parser.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_TIME_PARSER_HPP_INCLUDED
-#define _TIME_SHIELD_TIME_PARSER_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_TIME_PARSER_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_TIME_PARSER_HPP_INCLUDED
 
 /// \file time_parser.hpp
 /// \brief Header file with functions for parsing dates and times in ISO8601 format and converting them to various timestamp formats.
@@ -1767,4 +1767,4 @@ namespace time_shield {
 
 };
 
-#endif // _TIME_SHIELD_TIME_PARSER_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_TIME_PARSER_HPP_INCLUDED
diff --git a/include/time_shield/time_struct.hpp b/include/time_shield/time_struct.hpp
index b594b10f..f4ff0de8 100644
--- a/include/time_shield/time_struct.hpp
+++ b/include/time_shield/time_struct.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_TIME_STRUCT_HPP_INCLUDED
-#define _TIME_SHIELD_TIME_STRUCT_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_TIME_STRUCT_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_TIME_STRUCT_HPP_INCLUDED
 
 /// \file time_struct.hpp
 /// \brief Header for time structure and related functions.
@@ -37,4 +37,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // _TIME_SHIELD_TIME_STRUCT_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_TIME_STRUCT_HPP_INCLUDED
diff --git a/include/time_shield/time_unit_conversions.hpp b/include/time_shield/time_unit_conversions.hpp
index 9ebdb22e..4c2bce14 100644
--- a/include/time_shield/time_unit_conversions.hpp
+++ b/include/time_shield/time_unit_conversions.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_TIME_UNIT_CONVERSIONS_HPP_INCLUDED
-#define _TIME_SHIELD_TIME_UNIT_CONVERSIONS_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_TIME_UNIT_CONVERSIONS_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_TIME_UNIT_CONVERSIONS_HPP_INCLUDED
 
 /// \file time_unit_conversions.hpp
 /// \brief Helper functions for unit conversions between seconds, minutes, hours, and milliseconds.
@@ -484,4 +484,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // _TIME_SHIELD_TIME_UNIT_CONVERSIONS_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_TIME_UNIT_CONVERSIONS_HPP_INCLUDED
diff --git a/include/time_shield/time_utils.hpp b/include/time_shield/time_utils.hpp
index e68b066f..787c62eb 100644
--- a/include/time_shield/time_utils.hpp
+++ b/include/time_shield/time_utils.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_TIME_UTILS_HPP_INCLUDED
-#define _TIME_SHIELD_TIME_UTILS_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_TIME_UTILS_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_TIME_UTILS_HPP_INCLUDED
 
 /// \file time_utils.hpp
 /// \brief Header file with time-related utility functions.
@@ -343,4 +343,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // _TIME_SHIELD_TIME_UTILS_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_TIME_UTILS_HPP_INCLUDED
diff --git a/include/time_shield/time_zone_conversions.hpp b/include/time_shield/time_zone_conversions.hpp
index ce46ad64..e43a9e6f 100644
--- a/include/time_shield/time_zone_conversions.hpp
+++ b/include/time_shield/time_zone_conversions.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_TIME_ZONE_CONVERSIONS_HPP_INCLUDED
-#define _TIME_SHIELD_TIME_ZONE_CONVERSIONS_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_TIME_ZONE_CONVERSIONS_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_TIME_ZONE_CONVERSIONS_HPP_INCLUDED
 
 /// \file time_zone_conversions.hpp
 /// \brief Helpers for converting supported regional time zones and UTC.
@@ -1065,4 +1065,4 @@ namespace time_shield {
 
 } // namespace time_shield
 
-#endif // _TIME_SHIELD_TIME_ZONE_CONVERSIONS_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_TIME_ZONE_CONVERSIONS_HPP_INCLUDED
diff --git a/include/time_shield/time_zone_offset.hpp b/include/time_shield/time_zone_offset.hpp
index 82db917c..fcaf3e51 100644
--- a/include/time_shield/time_zone_offset.hpp
+++ b/include/time_shield/time_zone_offset.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_TIME_ZONE_OFFSET_HPP_INCLUDED
-#define _TIME_SHIELD_TIME_ZONE_OFFSET_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_TIME_ZONE_OFFSET_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_TIME_ZONE_OFFSET_HPP_INCLUDED
 
 /// \file time_zone_offset.hpp
 /// \brief UTC offset arithmetic helpers (UTC <-> local) and TimeZoneStruct offset extraction.
@@ -74,4 +74,4 @@ namespace time_shield {
 
 } // namespace time_shield
 
-#endif
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_TIME_ZONE_OFFSET_HPP_INCLUDED
diff --git a/include/time_shield/time_zone_offset_conversions.hpp b/include/time_shield/time_zone_offset_conversions.hpp
index 116b947b..dbf8c66e 100644
--- a/include/time_shield/time_zone_offset_conversions.hpp
+++ b/include/time_shield/time_zone_offset_conversions.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_TIME_ZONE_OFFSET_CONVERSIONS_HPP_INCLUDED
-#define _TIME_SHIELD_TIME_ZONE_OFFSET_CONVERSIONS_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_TIME_ZONE_OFFSET_CONVERSIONS_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_TIME_ZONE_OFFSET_CONVERSIONS_HPP_INCLUDED
 
 /// \file time_zone_offset_conversions.hpp
 /// \brief Conversions between numeric offsets and TimeZoneStruct.
@@ -68,4 +68,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // _TIME_SHIELD_TIME_ZONE_OFFSET_CONVERSIONS_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_TIME_ZONE_OFFSET_CONVERSIONS_HPP_INCLUDED
diff --git a/include/time_shield/time_zone_struct.hpp b/include/time_shield/time_zone_struct.hpp
index c685209b..a0cd0446 100644
--- a/include/time_shield/time_zone_struct.hpp
+++ b/include/time_shield/time_zone_struct.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_TIME_ZONE_STRUCT_HPP_INCLUDED
-#define _TIME_SHIELD_TIME_ZONE_STRUCT_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_TIME_ZONE_STRUCT_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_TIME_ZONE_STRUCT_HPP_INCLUDED
 
 /// \file time_zone_struct.hpp
 /// \brief Header for time zone structure and related functions.
@@ -118,4 +118,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // _TIME_SHIELD_TIME_ZONE_STRUCT_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_TIME_ZONE_STRUCT_HPP_INCLUDED
diff --git a/include/time_shield/types.hpp b/include/time_shield/types.hpp
index 7ce88fea..06e0407a 100644
--- a/include/time_shield/types.hpp
+++ b/include/time_shield/types.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_TYPES_HPP_INCLUDED
-#define _TIME_SHIELD_TYPES_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_TYPES_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_TYPES_HPP_INCLUDED
 
 /// \file types.hpp
 /// \brief Type definitions for time-related units and formats.
@@ -64,4 +64,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // _TIME_SHIELD_TYPES_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_TYPES_HPP_INCLUDED
diff --git a/include/time_shield/unix_time_conversions.hpp b/include/time_shield/unix_time_conversions.hpp
index 230cea00..a6251028 100644
--- a/include/time_shield/unix_time_conversions.hpp
+++ b/include/time_shield/unix_time_conversions.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_UNIX_TIME_CONVERSIONS_HPP_INCLUDED
-#define _TIME_SHIELD_UNIX_TIME_CONVERSIONS_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_UNIX_TIME_CONVERSIONS_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_UNIX_TIME_CONVERSIONS_HPP_INCLUDED
 
 /// \file unix_time_conversions.hpp
 /// \brief Conversions related to UNIX-based time units and epochs.
@@ -329,4 +329,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // _TIME_SHIELD_UNIX_TIME_CONVERSIONS_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_UNIX_TIME_CONVERSIONS_HPP_INCLUDED
diff --git a/include/time_shield/validation.hpp b/include/time_shield/validation.hpp
index 5904f81c..bfc060a3 100644
--- a/include/time_shield/validation.hpp
+++ b/include/time_shield/validation.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_VALIDATION_HPP_INCLUDED
-#define _TIME_SHIELD_VALIDATION_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_VALIDATION_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_VALIDATION_HPP_INCLUDED
 
 /// \file validation.hpp
 /// \brief Header file with time-related validation functions.
@@ -394,4 +394,4 @@ namespace time_shield {
 
 } // namespace time_shield
 
-#endif // _TIME_SHIELD_VALIDATION_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_VALIDATION_HPP_INCLUDED
diff --git a/include/time_shield/workday_conversions.hpp b/include/time_shield/workday_conversions.hpp
index c72b9aa7..2d615dad 100644
--- a/include/time_shield/workday_conversions.hpp
+++ b/include/time_shield/workday_conversions.hpp
@@ -1,7 +1,7 @@
 // SPDX-License-Identifier: MIT
 #pragma once
-#ifndef _TIME_SHIELD_WORKDAY_CONVERSIONS_HPP_INCLUDED
-#define _TIME_SHIELD_WORKDAY_CONVERSIONS_HPP_INCLUDED
+#ifndef TIME_SHIELD_HEADER_TIME_SHIELD_WORKDAY_CONVERSIONS_HPP_INCLUDED
+#define TIME_SHIELD_HEADER_TIME_SHIELD_WORKDAY_CONVERSIONS_HPP_INCLUDED
 
 /// \file workday_conversions.hpp
 /// \brief Helpers for computing workday-related timestamps.
@@ -340,4 +340,4 @@ namespace time_shield {
 
 }; // namespace time_shield
 
-#endif // _TIME_SHIELD_WORKDAY_CONVERSIONS_HPP_INCLUDED
+#endif // TIME_SHIELD_HEADER_TIME_SHIELD_WORKDAY_CONVERSIONS_HPP_INCLUDED