diff --git a/src/core/common_code/common_code.h b/src/core/common_code/common_code.h
index 24159e7..9f5c083 100644
--- a/src/core/common_code/common_code.h
+++ b/src/core/common_code/common_code.h
@@ -201,3 +201,10 @@ static_assert(std::is_trivially_copyable_v<CommonCode>);
 #include "internal/common_code.inl"
 #include "internal/mirror.inl"
 #include "internal/check.inl"
+
+template <>
+struct std::hash<klotski::codec::CommonCode> {
+    constexpr std::size_t operator()(const klotski::codec::CommonCode &c) const noexcept {
+        return std::hash<uint64_t>{}(c.unwrap());
+    }
+};
diff --git a/src/core/common_code/internal/common_code.inl b/src/core/common_code/internal/common_code.inl
index de55de5..e640153 100644
--- a/src/core/common_code/internal/common_code.inl
+++ b/src/core/common_code/internal/common_code.inl
@@ -53,6 +53,8 @@ inline ShortCode CommonCode::to_short_code() const {
     return ShortCode(*this);
 }
 
+// ----------------------------------------------------------------------------------------- //
+
 inline std::string CommonCode::to_string(const bool shorten) const {
     if (!shorten) {
         return string_encode(code_); // with full length
@@ -60,8 +62,6 @@ inline std::string CommonCode::to_string(const bool shorten) const {
     return string_encode_shorten(code_); // without trailing zero
 }
 
-// ----------------------------------------------------------------------------------------- //
-
 inline std::optional<CommonCode> CommonCode::from_string(const std::string_view common_code) {
     return string_decode(common_code).transform(unsafe_create);
 }
@@ -138,18 +138,3 @@ constexpr auto operator<=>(const CommonCode &lhs, const CommonCode &rhs) {
 // ----------------------------------------------------------------------------------------- //
 
 } // namespace klotski::codec
-
-// ----------------------------------------------------------------------------------------- //
-
-namespace std {
-
-template <>
-struct hash<klotski::codec::CommonCode> {
-    constexpr std::size_t operator()(const klotski::codec::CommonCode &c) const noexcept {
-        return std::hash<uint64_t>{}(c.unwrap());
-    }
-};
-
-} // namespace std
-
-// ----------------------------------------------------------------------------------------- //
diff --git a/src/core/main.cc b/src/core/main.cc
index 8540fa5..e477c84 100644
--- a/src/core/main.cc
+++ b/src/core/main.cc
@@ -79,6 +79,13 @@ int main() {
     static_assert(raw_code.to_vertical_mirror() == 0xFFF5E2FCF4DA603);
     static_assert(raw_code.to_horizontal_mirror() == 0x603EDF5CAFFF5E2);
 
+    static_assert(ShortCode::check(4091296));
+    constexpr auto short_code = ShortCode::unsafe_create(4091296);
+
+    static_assert(short_code.unwrap() == 4091296);
+    static_assert(static_cast<uint32_t>(short_code) == 4091296);
+    static_assert(short_code == ShortCode::create(4091296)->unwrap());
+
     // const auto code = CommonCode::unsafe_create(0x1A9BF0C00).to_raw_code();
     // const auto code = CommonCode::unsafe_create(0x4FEA13400).to_raw_code();
     // FastCal fc {code};
diff --git a/src/core/raw_code/internal/check.inl b/src/core/raw_code/internal/check.inl
index f8a6759..1723913 100644
--- a/src/core/raw_code/internal/check.inl
+++ b/src/core/raw_code/internal/check.inl
@@ -1,33 +1,9 @@
 #pragma once
 
-#ifndef KLSK_NDEBUG
-// TODO: only for debug output -> move to other header
-#include <format>
-#include <ostream>
-#endif
-
 #include "utils/common.h"
 
 namespace klotski::codec {
 
-#ifndef KLSK_NDEBUG
-inline std::ostream& operator<<(std::ostream &out, const RawCode self) {
-    constexpr auto char_map = std::to_array({
-        '.', // space
-        '~', '|', // 1x2 | 2x1
-        '*', '@', // 1x1 | 2x2
-        '?', '?', // unknown
-        '+', // fill
-    });
-    out << std::format("{:015X}\n", self.code_);
-    for (int addr = 0; addr < 60; addr += 3) {
-        out << char_map[(self.code_ >> addr) & 0b111];
-        out << &" "[(addr & 0b11) == 0b01] << &"\n"[(addr & 0b11) != 0b01];
-    }
-    return out;
-}
-#endif
-
 constexpr bool RawCode::check(uint64_t raw_code) {
     ///     MASK_1x1      |     MASK_1x2      |     MASK_2x1      |     MASK_2x2
     ///  100 000 000 000  |  000 100 000 000  |  000 000 000 000  |  000 100 000 000
diff --git a/src/core/raw_code/internal/raw_code.inl b/src/core/raw_code/internal/raw_code.inl
index 8ae3f1c..80c3075 100644
--- a/src/core/raw_code/internal/raw_code.inl
+++ b/src/core/raw_code/internal/raw_code.inl
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <format>
+
 #include "common_code/common_code.h"
 
 namespace klotski::codec {
@@ -93,19 +95,28 @@ constexpr auto operator<=>(const RawCode &lhs, const RawCode &rhs) {
 
 // ----------------------------------------------------------------------------------------- //
 
-} // namespace klotski::codec
-
-// ----------------------------------------------------------------------------------------- //
-
-namespace std {
+#ifndef KLSK_NDEBUG
+inline std::ostream& operator<<(std::ostream &out, const RawCode self) {
+    auto show = [code = self.code_](const int offset) {
+        constexpr auto char_map = std::to_array({
+            '.', // space
+            '~', '|', // 1x2 | 2x1
+            '*', '@', // 1x1 | 2x2
+            '?', '?', // unknown
+            '+', // fill
+        });
+        return char_map[(code >> (offset * 3)) & 0b111];
+    };
 
-template <>
-struct hash<klotski::codec::RawCode> {
-    constexpr std::size_t operator()(const klotski::codec::RawCode &r) const noexcept {
-        return std::hash<uint64_t>{}(r.unwrap());
+    out << std::format("{:015X}\n", self.code_);
+    for (int offset = 0; offset < 20; offset += 4) {
+        out << std::format("{} {} {} {}\n",
+            show(offset), show(offset + 1), show(offset + 2), show(offset + 3));
     }
-};
-
-} // namespace std
+    return out;
+}
+#endif
 
 // ----------------------------------------------------------------------------------------- //
+
+} // namespace klotski::codec
diff --git a/src/core/raw_code/raw_code.h b/src/core/raw_code/raw_code.h
index 6bb82d8..8c5641c 100644
--- a/src/core/raw_code/raw_code.h
+++ b/src/core/raw_code/raw_code.h
@@ -179,3 +179,10 @@ static_assert(std::is_trivially_copyable_v<RawCode>);
 #include "internal/convert.inl"
 #include "internal/mirror.inl"
 #include "internal/check.inl"
+
+template <>
+struct std::hash<klotski::codec::RawCode> {
+    constexpr std::size_t operator()(const klotski::codec::RawCode &r) const noexcept {
+        return std::hash<uint64_t>{}(r.unwrap());
+    }
+};
diff --git a/src/core/short_code/internal/short_code.inl b/src/core/short_code/internal/short_code.inl
index 8edefdf..827e6bd 100644
--- a/src/core/short_code/internal/short_code.inl
+++ b/src/core/short_code/internal/short_code.inl
@@ -117,18 +117,3 @@ constexpr auto operator<=>(const ShortCode &lhs, const ShortCode &rhs) {
 // ----------------------------------------------------------------------------------------- //
 
 } // namespace klotski::codec
-
-// ----------------------------------------------------------------------------------------- //
-
-namespace std {
-
-template <>
-struct hash<klotski::codec::ShortCode> {
-    constexpr std::size_t operator()(const klotski::codec::ShortCode &s) const noexcept {
-        return std::hash<uint32_t>{}(s.unwrap());
-    }
-};
-
-} // namespace std
-
-// ----------------------------------------------------------------------------------------- //
diff --git a/src/core/short_code/short_code.h b/src/core/short_code/short_code.h
index 9499291..54bcd48 100644
--- a/src/core/short_code/short_code.h
+++ b/src/core/short_code/short_code.h
@@ -91,15 +91,15 @@ public:
 
     // ------------------------------------------------------------------------------------- //
 
+    /// Build the conversion index.
+    static void speed_up(bool fast_mode);
+
     /// Explicit conversion to u32 code.
     explicit constexpr operator uint32_t() const;
 
     /// Check the validity of the original ShortCode.
     static constexpr bool check(uint32_t short_code);
 
-    /// Build the conversion index for ShortCode.
-    static void speed_up(bool fast_mode = false);
-
 #ifndef KLSK_NDEBUG
     /// Output string encoding of ShortCode only for debug.
     friend std::ostream& operator<<(std::ostream &out, ShortCode self);
@@ -195,3 +195,10 @@ static_assert(std::is_trivially_copyable_v<ShortCode>);
 #include "internal/short_code.inl"
 #include "internal/serialize.inl"
 #include "internal/convert.inl"
+
+template <>
+struct std::hash<klotski::codec::ShortCode> {
+    constexpr std::size_t operator()(const klotski::codec::ShortCode &s) const noexcept {
+        return std::hash<uint32_t>{}(s.unwrap());
+    }
+};