Add include guards and header comments to sources

34 files changed, 277 insertions, 19 deletions

diff --git a/src/core/config/boolean.cc b/src/core/config/boolean.cc
index 45d5a38..74c7b07 100644
--- a/src/core/config/boolean.cc
+++ b/src/core/config/boolean.cc
@@ -1,3 +1,8 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: boolean.cc
+// Description: Boolean config value
+
 #include "core/pch.hh"
 
 #include "core/config/boolean.hh"
diff --git a/src/core/config/boolean.hh b/src/core/config/boolean.hh
index cfd8b0b..238b978 100644
--- a/src/core/config/boolean.hh
+++ b/src/core/config/boolean.hh
@@ -1,3 +1,10 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: boolean.hh
+// Description: Boolean config value
+
+#ifndef CORE_CONFIG_BOOLEAN_HH
+#define CORE_CONFIG_BOOLEAN_HH
 #pragma once
 
 #include "core/config/ivalue.hh"
@@ -23,3 +30,5 @@ public:
     static bool from_string(std::string_view value);
 };
 } // namespace config
+
+#endif
diff --git a/src/core/config/ivalue.hh b/src/core/config/ivalue.hh
index 13e9a3a..088276a 100644
--- a/src/core/config/ivalue.hh
+++ b/src/core/config/ivalue.hh
@@ -1,3 +1,10 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: ivalue.hh
+// Description: Base config value interface
+
+#ifndef CORE_CONFIG_IVALUE_HH
+#define CORE_CONFIG_IVALUE_HH
 #pragma once
 
 namespace config
@@ -9,3 +16,5 @@ public:
     virtual std::string_view get(void) const = 0;
 };
 } // namespace config
+
+#endif
diff --git a/src/core/config/number.hh b/src/core/config/number.hh
index 4f185e1..eb1f462 100644
--- a/src/core/config/number.hh
+++ b/src/core/config/number.hh
@@ -1,3 +1,10 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: number.hh
+// Description: Arithmetic config value
+
+#ifndef CORE_CONFIG_NUMBER_HH
+#define CORE_CONFIG_NUMBER_HH
 #pragma once
 
 #include "core/config/ivalue.hh"
@@ -128,3 +135,5 @@ inline void config::Number<T>::set_limits(T min_value, T max_value)
     m_value = std::clamp(m_value, m_min_value, m_max_value);
     m_string = std::to_string(m_value);
 }
+
+#endif
diff --git a/src/core/config/string.cc b/src/core/config/string.cc
index 198b448..e5820f6 100644
--- a/src/core/config/string.cc
+++ b/src/core/config/string.cc
@@ -1,3 +1,8 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: string.cc
+// Description: String config value
+
 #include "core/pch.hh"
 
 #include "core/config/string.hh"
diff --git a/src/core/config/string.hh b/src/core/config/string.hh
index 8fd3901..faecb67 100644
--- a/src/core/config/string.hh
+++ b/src/core/config/string.hh
@@ -1,3 +1,10 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: string.hh
+// Description: String config value
+
+#ifndef CORE_CONFIG_STRING_HH
+#define CORE_CONFIG_STRING_HH
 #pragma once
 
 #include "core/config/ivalue.hh"
@@ -29,3 +36,5 @@ constexpr const char* config::String::c_str(void) const noexcept
 {
     return m_value.c_str();
 }
+
+#endif
diff --git a/src/core/io/buffer.cc b/src/core/io/buffer.cc
index d0fda49..dffd9bc 100644
--- a/src/core/io/buffer.cc
+++ b/src/core/io/buffer.cc
@@ -1,3 +1,8 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: buffer.cc
+// Description: QDataStream-esque buffer
+
 #include "core/pch.hh"
 
 #include "core/io/buffer.hh"
diff --git a/src/core/io/buffer.hh b/src/core/io/buffer.hh
index 450a86f..100a933 100644
--- a/src/core/io/buffer.hh
+++ b/src/core/io/buffer.hh
@@ -1,3 +1,12 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: buffer.hh
+// Description: QDataStream-esque buffer
+
+#ifndef CORE_IO_BUFFER_HH
+#define CORE_IO_BUFFER_HH
+#pragma once
+
 class ReadBuffer final {
 public:
     ReadBuffer(void) = default;
@@ -80,3 +89,5 @@ WriteBuffer& WriteBuffer::operator<<(const T value)
     write<T>(value);
     return *this;
 }
+
+#endif
diff --git a/src/core/io/cmdline.cc b/src/core/io/cmdline.cc
index d206cb8..0d1206a 100644
--- a/src/core/io/cmdline.cc
+++ b/src/core/io/cmdline.cc
@@ -1,3 +1,8 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: cmdline.cc
+// Description: Command-line arguments parser
+
 #include "core/pch.hh"
 
 #include "core/io/cmdline.hh"
diff --git a/src/core/io/cmdline.hh b/src/core/io/cmdline.hh
index c0d6db2..452072f 100644
--- a/src/core/io/cmdline.hh
+++ b/src/core/io/cmdline.hh
@@ -1,3 +1,10 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: cmdline.hh
+// Description: Command-line arguments parser
+
+#ifndef CORE_IO_CMDLINE_HH
+#define CORE_IO_CMDLINE_HH
 #pragma once
 
 namespace cmdline
@@ -9,3 +16,5 @@ std::string_view get(std::string_view option, std::string_view fallback = "");
 const char* get_cstr(std::string_view option, const char* fallback = nullptr);
 bool contains(std::string_view option);
 } // namespace cmdline
+
+#endif
diff --git a/src/core/io/config_map.cc b/src/core/io/config_map.cc
index 8634fd6..93fab2b 100644
--- a/src/core/io/config_map.cc
+++ b/src/core/io/config_map.cc
@@ -1,3 +1,8 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: config_map.cc
+// Description: Config parser
+
 #include "core/pch.hh"
 
 #include "core/io/config_map.hh"
diff --git a/src/core/io/config_map.hh b/src/core/io/config_map.hh
index 898103b..2e3f18f 100644
--- a/src/core/io/config_map.hh
+++ b/src/core/io/config_map.hh
@@ -1,3 +1,10 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: config_map.hh
+// Description: Config parser
+
+#ifndef CORE_IO_CONFIG_MAP_HH
+#define CORE_IO_CONFIG_MAP_HH
 #pragma once
 
 namespace config
@@ -24,3 +31,5 @@ public:
 private:
     std::unordered_map<std::string, config::IValue*> m_values;
 };
+
+#endif
diff --git a/src/core/io/physfs.cc b/src/core/io/physfs.cc
index b9fe91e..04aaf64 100644
--- a/src/core/io/physfs.cc
+++ b/src/core/io/physfs.cc
@@ -1,13 +1,18 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: physfs.cc
+// Description: PhysFS utilities
+
 #include "core/pch.hh"
 
 #include "core/io/physfs.hh"
 
-bool read_file(std::string_view path, std::vector<std::byte>& buffer)
+bool physfs::read_file(std::string_view path, std::vector<std::byte>& buffer)
 {
     auto file = PHYSFS_openRead(std::string(path).c_str());
 
     if(file == nullptr) {
-        spdlog::error("physfs: {}: {}", path, physfs_error());
+        spdlog::error("physfs: {}: {}", path, physfs::last_error());
         return false;
     }
 
@@ -20,12 +25,12 @@ bool read_file(std::string_view path, std::vector<std::byte>& buffer)
     return true;
 }
 
-bool read_file(std::string_view path, std::string& buffer)
+bool physfs::read_file(std::string_view path, std::string& buffer)
 {
     auto file = PHYSFS_openRead(std::string(path).c_str());
 
     if(file == nullptr) {
-        spdlog::error("physfs: {}: {}", path, physfs_error());
+        spdlog::error("physfs: {}: {}", path, physfs::last_error());
         return false;
     }
 
@@ -38,12 +43,12 @@ bool read_file(std::string_view path, std::string& buffer)
     return true;
 }
 
-bool write_file(std::string_view path, const std::vector<std::byte>& buffer)
+bool physfs::write_file(std::string_view path, const std::vector<std::byte>& buffer)
 {
     auto file = PHYSFS_openWrite(std::string(path).c_str());
 
     if(file == nullptr) {
-        spdlog::error("physfs: {}: {}", path, physfs_error());
+        spdlog::error("physfs: {}: {}", path, physfs::last_error());
         return false;
     }
 
@@ -53,12 +58,12 @@ bool write_file(std::string_view path, const std::vector<std::byte>& buffer)
     return true;
 }
 
-bool write_file(std::string_view path, const std::string& buffer)
+bool physfs::write_file(std::string_view path, const std::string& buffer)
 {
     auto file = PHYSFS_openWrite(std::string(path).c_str());
 
     if(file == nullptr) {
-        spdlog::error("physfs: {}: {}", path, physfs_error());
+        spdlog::error("physfs: {}: {}", path, physfs::last_error());
         return false;
     }
 
@@ -68,7 +73,7 @@ bool write_file(std::string_view path, const std::string& buffer)
     return true;
 }
 
-std::string_view physfs_error(void)
+std::string_view physfs::last_error(void)
 {
     auto error_code = PHYSFS_getLastErrorCode();
     auto error_string = PHYSFS_getErrorByCode(error_code);
diff --git a/src/core/io/physfs.hh b/src/core/io/physfs.hh
index 88f97de..8cf84be 100644
--- a/src/core/io/physfs.hh
+++ b/src/core/io/physfs.hh
@@ -1,8 +1,23 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: physfs.hh
+// Description: PhysFS utilities
+
+#ifndef CORE_IO_PHYSFS_HH
+#define CORE_IO_PHYSFS_HH
 #pragma once
 
+namespace physfs
+{
 bool read_file(std::string_view path, std::vector<std::byte>& buffer);
 bool read_file(std::string_view path, std::string& buffer);
 bool write_file(std::string_view path, const std::vector<std::byte>& buffer);
 bool write_file(std::string_view path, const std::string& buffer);
+} // namespace physfs
+
+namespace physfs
+{
+std::string_view last_error(void);
+} // namespace physfs
 
-std::string_view physfs_error(void);
+#endif
diff --git a/src/core/math/aabb.hh b/src/core/math/aabb.hh
index f3eb7bd..79f814a 100644
--- a/src/core/math/aabb.hh
+++ b/src/core/math/aabb.hh
@@ -1,3 +1,10 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: aabb.hh
+// Description: Axis-aligned bounding box
+
+#ifndef CORE_MATH_AABB_HH
+#define CORE_MATH_AABB_HH
 #pragma once
 
 #include "core/math/concepts.hh"
@@ -109,3 +116,5 @@ constexpr math::AABB<T> math::AABB<T>::push(const vector_type& vector) const
     result.max = max + vector;
     return result;
 }
+
+#endif
diff --git a/src/core/math/angles.hh b/src/core/math/angles.hh
index 174f320..b339323 100644
--- a/src/core/math/angles.hh
+++ b/src/core/math/angles.hh
@@ -1,3 +1,10 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: angles.hh
+// Description: Angle utilities
+
+#ifndef CORE_MATH_ANGLES_HH
+#define CORE_MATH_ANGLES_HH
 #pragma once
 
 #include "core/math/constexpr.hh"
@@ -101,3 +108,5 @@ inline void math::vectors(const glm::fvec3& angles, glm::fvec3* forward, glm::fv
         up->z = nsv.x * ncv.y * pcv.z + psv.y * psv.z;
     }
 }
+
+#endif
diff --git a/src/core/math/concepts.hh b/src/core/math/concepts.hh
index 6ad5cb7..5d1ef7d 100644
--- a/src/core/math/concepts.hh
+++ b/src/core/math/concepts.hh
@@ -1,3 +1,10 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: concepts.hh
+// Description: C++20 concepts that should be in standard library but are not
+
+#ifndef CORE_MATH_CONCEPTS_HH
+#define CORE_MATH_CONCEPTS_HH
 #pragma once
 
 namespace math
@@ -9,3 +16,5 @@ concept signed_arithmetic = std::is_arithmetic_v<type> && std::is_signed_v<type>
 template<typename type>
 concept unsigned_arithmetic = std::is_arithmetic_v<type> && std::is_unsigned_v<type>;
 } // namespace math
+
+#endif
diff --git a/src/core/math/constexpr.hh b/src/core/math/constexpr.hh
index 4158803..7aba4d2 100644
--- a/src/core/math/constexpr.hh
+++ b/src/core/math/constexpr.hh
@@ -1,3 +1,10 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: constexpr.hh
+// Description: Compile-time expressions
+
+#ifndef CORE_MATH_CONSTEXPR_HH
+#define CORE_MATH_CONSTEXPR_HH
 #pragma once
 
 #include "core/math/concepts.hh"
@@ -70,3 +77,5 @@ constexpr scalar math::radians(const scalar x)
 {
     return static_cast<scalar>(static_cast<double>(x) * M_PI / 180.0);
 }
+
+#endif
diff --git a/src/core/math/crc64.cc b/src/core/math/crc64.cc
index 99a4b20..ce1e1db 100644
--- a/src/core/math/crc64.cc
+++ b/src/core/math/crc64.cc
@@ -1,3 +1,8 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: crc64.cc
+// Description: Client-server synchronized CRC64
+
 #include "core/pch.hh"
 
 #include "core/math/crc64.hh"
diff --git a/src/core/math/crc64.hh b/src/core/math/crc64.hh
index 3ece0df..f593dc9 100644
--- a/src/core/math/crc64.hh
+++ b/src/core/math/crc64.hh
@@ -1,3 +1,10 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: crc64.hh
+// Description: Client-server synchronized CRC64
+
+#ifndef CORE_MATH_CRC64_HH
+#define CORE_MATH_CRC64_HH
 #pragma once
 
 namespace math
@@ -7,3 +14,5 @@ std::uint64_t crc64(const std::vector<std::byte>& buffer, std::uint64_t combine
 std::uint64_t crc64(const std::string& buffer, std::uint64_t combine = UINT64_C(0));
 std::uint64_t crc64(std::string_view buffer, std::uint64_t combine = UINT64_C(0));
 } // namespace math
+
+#endif
diff --git a/src/core/math/vectors.hh b/src/core/math/vectors.hh
index bc11dd0..2934bb6 100644
--- a/src/core/math/vectors.hh
+++ b/src/core/math/vectors.hh
@@ -1,11 +1,14 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: vectors.hh
+// Description: because NO ONE would POSSIBLY need integer-based distance calculations in a VOXEL game
+
+#ifndef CORE_MATH_VECTORS_HH
+#define CORE_MATH_VECTORS_HH
 #pragma once
 
 #include "core/math/concepts.hh"
 
-// core/vectors.hh - because NO ONE would POSSIBLY
-// need integer-based distance calculations in a
-// game about voxels. That would be INSANE! :D
-
 namespace math
 {
 template<math::arithmetic T>
@@ -41,3 +44,5 @@ constexpr static inline const T math::distance2(const glm::vec<3, T>& vector_a,
 {
     return math::length2(vector_a - vector_b);
 }
+
+#endif
diff --git a/src/core/pch.hh b/src/core/pch.hh
index 17417a5..9a99be7 100644
--- a/src/core/pch.hh
+++ b/src/core/pch.hh
@@ -1,3 +1,10 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: pch.hh
+// Description: Precompiled header
+
+#ifndef CORE_PCH_HH
+#define CORE_PCH_HH
 #pragma once
 
 #include <cinttypes>
@@ -47,3 +54,5 @@
 
 #include <stb_image.h>
 #include <stb_image_write.h>
+
+#endif
diff --git a/src/core/resource/image.cc b/src/core/resource/image.cc
index 6a2109e..aded098 100644
--- a/src/core/resource/image.cc
+++ b/src/core/resource/image.cc
@@ -1,3 +1,8 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: image.cc
+// Description: Image resource
+
 #include "core/pch.hh"
 
 #include "core/resource/image.hh"
@@ -31,18 +36,18 @@ static const void* image_load_func(const char* name, std::uint32_t flags)
     callbacks.skip = &stbi_physfs_skip;
     callbacks.eof = &stbi_physfs_eof;
 
-    stbi_set_flip_vertically_on_load(bool(flags & IMAGE_LOAD_FLIP));
+    stbi_set_flip_vertically_on_load(bool(flags & IMGFLAG_FLIP));
 
     auto file = PHYSFS_openRead(name);
 
     if(file == nullptr) {
-        spdlog::error("image: {}: {}", name, physfs_error());
+        spdlog::error("image: {}: {}", name, physfs::last_error());
         return nullptr;
     }
 
     int desired_channels;
 
-    if(flags & IMAGE_LOAD_GRAY) {
+    if(flags & IMGFLAG_GRAY) {
         desired_channels = STBI_grey;
     }
     else {
diff --git a/src/core/resource/image.hh b/src/core/resource/image.hh
index 575591f..4f93da6 100644
--- a/src/core/resource/image.hh
+++ b/src/core/resource/image.hh
@@ -1,7 +1,14 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: image.hh
+// Description: Image resource
+
+#ifndef CORE_RESOURCE_IMAGE_HH
+#define CORE_RESOURCE_IMAGE_HH
 #pragma once
 
-constexpr static unsigned int IMAGE_LOAD_GRAY = 0x0001U;
-constexpr static unsigned int IMAGE_LOAD_FLIP = 0x0002U;
+constexpr static unsigned int IMGFLAG_GRAY = 0x0001U;
+constexpr static unsigned int IMGFLAG_FLIP = 0x0002U;
 
 struct Image final {
     static void register_resource(void);
@@ -9,3 +16,5 @@ struct Image final {
     stbi_uc* pixels;
     glm::ivec2 size;
 };
+
+#endif
diff --git a/src/core/resource/resource.cc b/src/core/resource/resource.cc
index 926dfc5..6a9539f 100644
--- a/src/core/resource/resource.cc
+++ b/src/core/resource/resource.cc
@@ -1,3 +1,8 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: resource.cc
+// Description: Resource management
+
 #include "core/pch.hh"
 
 #include "core/resource/resource.hh"
diff --git a/src/core/resource/resource.hh b/src/core/resource/resource.hh
index 105c7ff..e2a5659 100644
--- a/src/core/resource/resource.hh
+++ b/src/core/resource/resource.hh
@@ -1,3 +1,10 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: resource.hh
+// Description: Resource management
+
+#ifndef CORE_RESOURCE_RESOURCE_HH
+#define CORE_RESOURCE_RESOURCE_HH
 #pragma once
 
 template<typename T>
@@ -51,3 +58,5 @@ resource_ptr<T> resource::find(std::string_view name)
     auto result = resource::detail::find_resource(typeid(T), name);
     return std::reinterpret_pointer_cast<const T>(result);
 }
+
+#endif
diff --git a/src/core/threading.cc b/src/core/threading.cc
index a1ae305..1e469ad 100644
--- a/src/core/threading.cc
+++ b/src/core/threading.cc
@@ -1,3 +1,8 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: threading.cc
+// Description: Thread pool wrapper
+
 #include "core/pch.hh"
 
 #include "core/threading.hh"
diff --git a/src/core/threading.hh b/src/core/threading.hh
index 14f17f8..ea4e11b 100644
--- a/src/core/threading.hh
+++ b/src/core/threading.hh
@@ -1,3 +1,10 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: threading.hh
+// Description: Thread pool wrapper
+
+#ifndef CORE_THREADING_HH
+#define CORE_THREADING_HH
 #pragma once
 
 enum class task_status : unsigned int {
@@ -44,3 +51,5 @@ inline void threading::submit(AT&&... args)
 {
     threading::detail::submit_new(new T(args...));
 }
+
+#endif
diff --git a/src/core/utils/epoch.cc b/src/core/utils/epoch.cc
index 36bdb79..9d66399 100644
--- a/src/core/utils/epoch.cc
+++ b/src/core/utils/epoch.cc
@@ -1,3 +1,8 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: epoch.cc
+// Description: UNIX time utilities
+
 #include "core/pch.hh"
 
 #include "core/utils/epoch.hh"
diff --git a/src/core/utils/epoch.hh b/src/core/utils/epoch.hh
index 4bf5460..5210e22 100644
--- a/src/core/utils/epoch.hh
+++ b/src/core/utils/epoch.hh
@@ -1,3 +1,10 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: epoch.hh
+// Description: UNIX time utilities
+
+#ifndef CORE_UTILS_EPOCH_HH
+#define CORE_UTILS_EPOCH_HH
 #pragma once
 
 namespace utils
@@ -13,3 +20,5 @@ std::int64_t signed_unix_seconds(void);
 std::int64_t signed_unix_milliseconds(void);
 std::int64_t signed_unix_microseconds(void);
 } // namespace utils
+
+#endif
diff --git a/src/core/utils/string.cc b/src/core/utils/string.cc
index dd3d567..154b04b 100644
--- a/src/core/utils/string.cc
+++ b/src/core/utils/string.cc
@@ -1,3 +1,8 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: string.cc
+// Description: String utilities
+
 #include "core/pch.hh"
 
 #include "core/utils/string.hh"
diff --git a/src/core/utils/string.hh b/src/core/utils/string.hh
index 827c3ca..36c83ce 100644
--- a/src/core/utils/string.hh
+++ b/src/core/utils/string.hh
@@ -1,3 +1,10 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: string.hh
+// Description: String utilities
+
+#ifndef CORE_UTILS_STRING_HH
+#define CORE_UTILS_STRING_HH
 #pragma once
 
 namespace utils
@@ -15,3 +22,5 @@ namespace utils
 {
 std::string trim_whitespace(const std::string& string);
 } // namespace utils
+
+#endif
diff --git a/src/core/version.cc.in b/src/core/version.cc.in
index 5424a73..d791149 100644
--- a/src/core/version.cc.in
+++ b/src/core/version.cc.in
@@ -1,3 +1,8 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: version.cc.in
+// Description: Version template
+
 #include "core/pch.hh"
 
 #include "core/version.hh"
diff --git a/src/core/version.hh b/src/core/version.hh
index c033a3e..d040fa5 100644
--- a/src/core/version.hh
+++ b/src/core/version.hh
@@ -1,3 +1,10 @@
+// SPDX-License-Identifier: BSD-2-Clause
+// Copyright (c) 2025 Kirill Dmitrievich
+// File: version.hh
+// Description: Version information
+
+#ifndef CORE_VERSION_HH
+#define CORE_VERSION_HH
 #pragma once
 
 namespace version
@@ -18,3 +25,5 @@ namespace version
 {
 extern const std::string_view full;
 } // namespace version
+
+#endif