diff --git a/build.bat b/build.bat
index 3158f280..1340f390 100644
--- a/build.bat
+++ b/build.bat
@@ -4,54 +4,29 @@ cd /D "%~dp0"
 if not exist build mkdir build
 pushd build
 
-::::::::::::::::::::::::::::::::
-::~ Unpack args
+set program_build_cmd=meta.exe %*
+set meta_build_cmd=cl.exe ../src/meta/meta.c /Od /Z7 /nologo /link /DEBUG:FULL /INCREMENTAL:NO
+set meta_rebuild_code=995692758
 
-for %%a in (%*) do set "%%a=1"
-
-if "%~1" == "" (
-    echo [No arguments provided, assuming default `pp` build]
-    set meta=1
-    set pp=1
-)
-
-if "%~1" == "release" if "%~2" == "" (
-    echo [No arguments provided, assuming default 'pp' build]
-    set meta=1
-    set pp=1
-)
-
-if not "%release%" == "1" set debug=1
-
-if "%release%" == "1" echo [Release]
-if "%debug%" == "1" echo [Debug]
-
-::::::::::::::::::::::::::::::::
-::~ Build meta program
-
-if "%meta%" == "1" (
-    echo [Building meta]
-
-    "cl" ../src/meta/meta.c /Od /Z7 /nologo /link /DEBUG:FULL /INCREMENTAL:NO
-
-    if not "!errorlevel!" == "0" (
-        echo .
-        echo Failed to build meta program
-        exit /b 1
+::- Meta build
+:meta_build
+if not exist meta.exe (
+    echo [Meta build]
+    %meta_build_cmd%
+    set "rc=!errorlevel!"
+    if !rc! NEQ 0 (
+        exit /b !rc!
     )
 )
 
-::::::::::::::::::::::::::::::::
-::~ Build power play
-
-if "%pp%" == "1" (
-    echo [Building power play]
-
-    "meta.exe" pp
-
-    if not "!errorlevel!" == "0" (
-        echo.
-        echo Failed to run meta program
-        exit /b 1
+::- Program build
+echo [Build]
+%program_build_cmd%
+set "rc=!errorlevel!"
+if !rc! NEQ 0 (
+    if !rc! EQU %meta_rebuild_code% (
+        del meta.exe
+        goto meta_build
     )
+    exit /b !rc!
 )
diff --git a/src/base/base_string.c b/src/base/base_string.c
index 5838c6d0..3e0820ec 100644
--- a/src/base/base_string.c
+++ b/src/base/base_string.c
@@ -2,7 +2,6 @@
 //~ Conversion helpers
 
 //- Char conversion
-
 String StringFromChar(Arena *arena, char c)
 {
     u8 *dst = PushStructNoZero(arena, u8);
@@ -15,7 +14,6 @@ String StringFromChar(Arena *arena, char c)
 }
 
 //- Unsigned int conversion
-
 String StringFromU64(Arena *arena, u64 n, u64 base, u64 zfill)
 {
     /* Base too large */
@@ -56,7 +54,6 @@ String StringFromU64(Arena *arena, u64 n, u64 base, u64 zfill)
 }
 
 //- Signed int conversion
-
 String StringFromI64(Arena *arena, i64 n, u64 base, u64 zfill)
 {
     u8 *final_text = PushDry(arena, u8);
@@ -78,7 +75,6 @@ String StringFromI64(Arena *arena, i64 n, u64 base, u64 zfill)
 }
 
 //- Pointer conversion
-
 String StringFromPtr(Arena *arena, void *ptr)
 {
     String prepend = PushString(arena, Lit("0x"));
@@ -91,24 +87,23 @@ String StringFromPtr(Arena *arena, void *ptr)
 }
 
 //- Floating point conversion
-
 String StringFromF64(Arena *arena, f64 f, u32 precision)
 {
     TempArena scratch = BeginScratch(arena);
-    u8 *final_text = PushDry(arena, u8);
-    u64 final_len = 0;
+    String result = ZI;
+    result.text = PushDry(arena, u8);
 
     if (IsF32Nan(f))
     {
-        final_len += PushString(arena, Lit("NaN")).len;
+        result.len += PushString(arena, Lit("NaN")).len;
     }
     else if (f == F64Infinity)
     {
-        final_len += PushString(arena, Lit("inf")).len;
+        result.len += PushString(arena, Lit("inf")).len;
     }
     else if (f == -F64Infinity)
     {
-        final_len += PushString(arena, Lit("-inf")).len;
+        result.len += PushString(arena, Lit("-inf")).len;
     }
     else
     {
@@ -116,7 +111,7 @@ String StringFromF64(Arena *arena, f64 f, u32 precision)
         {
             StringFromChar(arena, '-');
             f = -f;
-            ++final_len;
+            ++result.len;
         }
 
         /* Add one half of next precision level to round up */
@@ -142,7 +137,7 @@ String StringFromF64(Arena *arena, f64 f, u32 precision)
             PushStructsNoZero(arena, u8, backwards_text_len);
             for (u64 i = backwards_text_len; i-- > 0;)
             {
-                final_text[final_len++] = backwards_text[i];
+                result.text[result.len++] = backwards_text[i];
             }
         }
 
@@ -157,19 +152,36 @@ String StringFromF64(Arena *arena, f64 f, u32 precision)
                 part_decimal -= digit;
                 StringFromChar(arena, IntChars[digit % 10]);
             }
-            final_len += (u64)precision + 1;
+            result.len += (u64)precision + 1;
         }
     }
 
     EndScratch(scratch);
-
-    return (String)
-    {
-        .len = final_len,
-        .text = final_text
-    };
+    return result;
 }
 
+//- Handle conversion
+String StringFromhandle(Arena *arena, u64 v0, u64 v1)
+{
+    String result = ZI;
+    result.text = PushDry(arena, u8);
+    result.len += PushString(arena, Lit("h")).len;
+    result.len += StringFromU64(arena, v0, 16, 0).len;
+    result.len += PushString(arena, Lit("x")).len;
+    result.len += StringFromU64(arena, v1, 16, 0).len;
+    return result;
+}
+
+//- Uid conversion
+String StringFromUid(Arena *arena, Uid uid)
+{
+    String result = ZI;
+    result.text = PushDry(arena, u8);
+    result.len += StringFromU64(arena, (uid.hi >> 32), 16, 8).len;
+    return result;
+}
+
+
 ////////////////////////////////
 //~ String helpers
 
@@ -345,31 +357,6 @@ b32 EqString(String str1, String str2)
     return eq;
 }
 
-i32 CmpString(String str1, String str2)
-{
-    i32 result = 0;
-    for (u64 i = 0; i < MinU64(str1.len, str2.len); ++i)
-    {
-        result = str1.text[i] - str2.text[i];
-        if (result != 0)
-        {
-            break;
-        }
-    }
-    if (result == 0)
-    {
-        if (str1.len > str2.len)
-        {
-            result = str1.text[str2.len];
-        }
-        else if (str2.len > str1.len)
-        {
-            result = str2.text[str1.len];
-        }
-    }
-    return result;
-}
-
 //- Match
 
 b32 StringContains(String str, String substring)
@@ -591,6 +578,16 @@ String StringFormatV(Arena *arena, String fmt, va_list args)
                     parsed_str = StringFromF64(arena, arg.value.f, arg.precision);
                 } break;
 
+                case FmtKind_Handle:
+                {
+                    parsed_str = StringFromhandle(arena, arg.value.handle.h64[0], arg.value.handle.h64[1]);
+                } break;
+
+                case FmtKind_Uid:
+                {
+                    parsed_str = StringFromUid(arena, arg.value.uid);
+                } break;
+
                 case FmtKind_End:
                 {
                     /* Unexpected end. Not enough FMT args passed to function. */
@@ -636,7 +633,7 @@ String StringFormatV(Arena *arena, String fmt, va_list args)
     };
 }
 
-String _StringFormat(Arena *arena, String fmt, ...)
+String StringFormat_(Arena *arena, String fmt, ...)
 {
     va_list args;
     va_start(args, fmt);
diff --git a/src/base/base_string.h b/src/base/base_string.h
index 6b58325b..80f80631 100644
--- a/src/base/base_string.h
+++ b/src/base/base_string.h
@@ -86,6 +86,8 @@ String StringFromU64(Arena *arena, u64 n, u64 base, u64 zfill);
 String StringFromI64(Arena *arena, i64 n, u64 base, u64 zfill);
 String StringFromPtr(Arena *arena, void *ptr);
 String StringFromF64(Arena *arena, f64 f, u32 precision);
+String StringFromhandle(Arena *arena, u64 v0, u64 v1);
+String StringFromUid(Arena *arena, Uid uid);
 
 ////////////////////////////////
 //~ String helpers
@@ -98,7 +100,6 @@ StringArray SplitString(Arena *arena, String str, String delim);
 String IndentString(Arena *arena, String str, u32 indent);
 String LowerString(Arena *arena, String str);
 b32 EqString(String str1, String str2);
-i32 CmpString(String str1, String str2);
 b32 StringContains(String str, String substring);
 b32 StringStartsWith(String str, String substring);
 b32 StringEndsWith(String str, String substring);
@@ -134,9 +135,9 @@ String StringFromList(Arena *arena, StringList l, String separator);
 #define FmtEnd              (FmtArg) {.kind = FmtKind_End}
 
 //- Format functions
-#define StringF(arena, lit, ...) _StringFormat((arena), Lit(lit), __VA_ARGS__, FmtEnd)
-#define StringFormat(arena, fmt, ...) _StringFormat((arena), (fmt), __VA_ARGS__, FmtEnd)
-String _StringFormat(Arena *arena, String fmt, ...);
+#define StringF(arena, lit, ...) StringFormat_((arena), Lit(lit), __VA_ARGS__, FmtEnd)
+#define StringFormat(arena, fmt, ...) StringFormat_((arena), (fmt), __VA_ARGS__, FmtEnd)
+String StringFormat_(Arena *arena, String fmt, ...);
 String StringFormatV(Arena *arena, String fmt, va_list args);
 
 ////////////////////////////////
diff --git a/src/base/base_win32/base_win32.c b/src/base/base_win32/base_win32.c
index ac529faf..71422e6f 100644
--- a/src/base/base_win32/base_win32.c
+++ b/src/base/base_win32/base_win32.c
@@ -1,11 +1,5 @@
 W32_SharedState W32_shared_state = ZI;
 
-////////////////////////////////
-//~ Windows libs
-
-#pragma comment(lib, "kernel32")
-#pragma comment(lib, "user32")
-
 ////////////////////////////////
 //~ @hookdef OS startup hook
 
@@ -58,18 +52,8 @@ i16 ThreadId(void)
 
 ////////////////////////////////
 //~ @hookdef Randomness hooks
-////////////////////////////////
-//~ True randomness
 
-#if PlatformIsWindows
-#if 0
-# define BCRYPT_RNG_ALG_HANDLE   ((void *)0x00000081)
-u32 BCryptGenRandom(void *algorithm, u8 *buffer, u32 buffer_size, u32 flags);
-#endif
 void TrueRand(String buffer)
 {
     BCryptGenRandom(BCRYPT_RNG_ALG_HANDLE, (u8 *)buffer.text, buffer.len, 0);
 }
-#else
-# error TrueRand not implemented for this platform
-#endif
diff --git a/src/base/base_win32/base_win32.h b/src/base/base_win32/base_win32.h
index 67837b7b..5eb5cea8 100644
--- a/src/base/base_win32/base_win32.h
+++ b/src/base/base_win32/base_win32.h
@@ -1,3 +1,15 @@
+////////////////////////////////
+//~ Win32 libs
+
+#ifndef BCRYPT_RNG_ALG_HANDLE
+#define BCRYPT_RNG_ALG_HANDLE ((void *)0x00000081)
+u32 BCryptGenRandom(void *algorithm, u8 *buffer, u32 buffer_size, u32 flags);
+#endif
+
+#pragma comment(lib, "kernel32")
+#pragma comment(lib, "user32")
+#pragma comment(lib, "bcrypt")
+
 ////////////////////////////////
 //~ Shared state
 
diff --git a/src/base/base_win32/base_win32_job.c b/src/base/base_win32/base_win32_job.c
index 8cf6e6e2..7b27fdfd 100644
--- a/src/base/base_win32/base_win32_job.c
+++ b/src/base/base_win32/base_win32_job.c
@@ -1,19 +1,5 @@
 W32_SharedJobCtx W32_shared_job_ctx = ZI;
 
-////////////////////////////////
-//~ Win32 libs
-
-#pragma comment(lib, "kernel32")
-#pragma comment(lib, "user32")
-#pragma comment(lib, "shell32")
-#pragma comment(lib, "ole32")
-#pragma comment(lib, "winmm")
-#pragma comment(lib, "dwmapi")
-#pragma comment(lib, "bcrypt")
-#pragma comment(lib, "synchronization")
-#pragma comment(lib, "avrt")
-#pragma comment(lib, "ws2_32.lib")
-
 ////////////////////////////////
 //~ @hookdef Startup
 
diff --git a/src/base/base_win32/base_win32_job.h b/src/base/base_win32/base_win32_job.h
index 0e8a5e89..daa16a29 100644
--- a/src/base/base_win32/base_win32_job.h
+++ b/src/base/base_win32/base_win32_job.h
@@ -1,5 +1,5 @@
 ////////////////////////////////
-//~ Win32 headers
+//~ Win32 libs
 
 #pragma warning(push, 0)
 #  include <WinSock2.h>
@@ -9,11 +9,20 @@
 #  include <ShlObj_core.h>
 #  include <fileapi.h>
 #  include <dwmapi.h>
-#  include <bcrypt.h>
 #  include <avrt.h>
 #  include <shellapi.h>
 #pragma warning(pop)
 
+#pragma comment(lib, "kernel32")
+#pragma comment(lib, "user32")
+#pragma comment(lib, "shell32")
+#pragma comment(lib, "ole32")
+#pragma comment(lib, "winmm")
+#pragma comment(lib, "dwmapi")
+#pragma comment(lib, "synchronization")
+#pragma comment(lib, "avrt")
+#pragma comment(lib, "ws2_32.lib")
+
 ////////////////////////////////
 //~ Thread types
 
diff --git a/src/gpu/gpu_core.h b/src/gpu/gpu_core.h
index aaf8616e..e0fe6500 100644
--- a/src/gpu/gpu_core.h
+++ b/src/gpu/gpu_core.h
@@ -12,20 +12,22 @@ Struct(GPU_Swapchain);
 //~ Queue types
 
 #define GPU_MultiQueueEnabled !ProfilingIsEnabled
-typedef i32 GPU_QueueKind;
+Enum(GPU_QueueKind)
+{
 #if GPU_MultiQueueEnabled
-# define GPU_QueueKind_Direct            0
-# define GPU_QueueKind_Compute           1
-# define GPU_QueueKind_Copy              2
-# define GPU_QueueKind_BackgroundCopy    3
-# define GPU_NumQueues                   4
+    GPU_QueueKind_Direct            = 0,
+    GPU_QueueKind_Compute           = 1,
+    GPU_QueueKind_Copy              = 2,
+    GPU_QueueKind_BackgroundCopy    = 3,
+    GPU_NumQueues                   = 4
 #else
-# define GPU_QueueKind_Direct            0
-# define GPU_QueueKind_Compute           0
-# define GPU_QueueKind_Copy              0
-# define GPU_QueueKind_BackgroundCopy    0
-# define GPU_NumQueues                   1
+    GPU_QueueKind_Direct            = 0,
+    GPU_QueueKind_Compute           = 0,
+    GPU_QueueKind_Copy              = 0,
+    GPU_QueueKind_BackgroundCopy    = 0,
+    GPU_NumQueues                   = 1
 #endif
+};
 
 ////////////////////////////////
 //~ Format types
diff --git a/src/meta/meta.c b/src/meta/meta.c
index 28e6b519..071b5baa 100644
--- a/src/meta/meta.c
+++ b/src/meta/meta.c
@@ -1,5 +1,7 @@
 /* TODO: Move decls to meta.h */
 
+#define MetaRebuildCode 0x3b5910d6
+
 ////////////////////////////////
 //~ Metaprogram default compiler definitions
 
@@ -732,69 +734,70 @@ Error *PushError(Arena *arena, ErrorList *list, String file, i64 pos, String s)
     return e;
 }
 
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
 ////////////////////////////////
 //~ Entry point
 
 i32 main(i32 argc, u8 **argv)
 {
-    i32 ret = 0;
-
     //- Startup
     StartupBase();
     OS_Startup();
     Arena *arena  = AcquireArena(Gibi(64));
 
+    i32 ret = 0;
+    ErrorList errors = ZI;
+
     //- Unpack args
-    StringList starting_layer_names = ZI;
-    StringList args = ZI;
-    i32 hyphens = 0;
     for (i32 i = 1; i < argc; ++i)
     {
         String arg = StringFromCstrNoLimit(argv[i]);
-        if (EqString(arg, Lit("-")))
+    }
+
+    //- Return if metaprogram is dirty
+    {
+        /* Read old metahash */
+        u64 old_metahash = 0;
+        if (F_IsFile(Lit("metahash.dat")))
         {
-            ++hyphens;
+            String hashes_str = F_DataFromFile(arena, Lit("metahash.dat"));
+            if (hashes_str.len == sizeof(old_metahash))
+            {
+                CopyBytes(&old_metahash, hashes_str.text, sizeof(old_metahash));
+            }
+            OS_Rm(Lit("metahash.dat"));
+        }
+
+        /* Calculate new metahash */
+        u64 new_metahash = 0;
+        {
+            StringList check_files = ZI;
+            F_FilesFromDir(arena, &check_files, Lit("../src/meta"), F_IterFlag_Recurse);
+            F_FilesFromDir(arena, &check_files, Lit("../src/prof"), F_IterFlag_Recurse);
+            PushStringToList(arena, &check_files, Lit("../src/config.h"));
+            for (StringListNode *n = check_files.first; n; n = n->next)
+            {
+                String file = n->s;
+                new_metahash = RandU64FromSeeds(HashFnv64(new_metahash, file), OS_LastWriteTimestampFromPath(file));
+            }
+        }
+
+        /* Exit if metaprogram needs recompilation */
+        if (old_metahash == 0 || old_metahash == new_metahash)
+        {
+            F_ClearWrite(Lit("metahash.dat"), StringFromStruct(&new_metahash));
         }
         else
         {
-            if (hyphens == 0)
-            {
-                PushStringToList(arena, &starting_layer_names, arg);
-            }
-            else
-            {
-                PushStringToList(arena, &args, arg);
-            }
+            Echo(Lit("Metaprogram is dirty"));
+            return MetaRebuildCode;
         }
     }
 
-    ErrorList errors = ZI;
+    //- Extract layer topography
     StringList src_dirs = ZI;
+    StringList starting_layer_names = ZI;
     PushStringToList(arena, &src_dirs, Lit("../src"));
+    PushStringToList(arena, &starting_layer_names, Lit("pp"));
     L_Topo topo = L_TopoFromLayerName(arena, starting_layer_names, src_dirs);
 
     //- Process topo errors
diff --git a/src/meta/meta_base/meta_base_inc.h b/src/meta/meta_base/meta_base_inc.h
index 0f191d71..b075523d 100644
--- a/src/meta/meta_base/meta_base_inc.h
+++ b/src/meta/meta_base/meta_base_inc.h
@@ -4,6 +4,7 @@
 #include "meta_base_memory.h"
 #include "meta_base_arena.h"
 #include "meta_base_math.h"
+#include "meta_base_rand.h"
 #include "meta_base_uni.h"
 #include "meta_base_string.h"
 #include "meta_base_util.h"
@@ -14,6 +15,7 @@
 #include "meta_base_memory.c"
 #include "meta_base_string.c"
 #include "meta_base_uni.c"
+#include "meta_base_rand.c"
 
 //- Win32
 #if PlatformIsWindows
diff --git a/src/meta/meta_base/meta_base_rand.c b/src/meta/meta_base/meta_base_rand.c
new file mode 100644
index 00000000..05c6fb13
--- /dev/null
+++ b/src/meta/meta_base/meta_base_rand.c
@@ -0,0 +1,43 @@
+////////////////////////////////
+//~ Stateful randomness
+
+u64 RandU64FromState(RandState *state)
+{
+    u64 seed = state->seed;
+    if (seed == 0)
+    {
+        TrueRand(StringFromStruct(&seed));
+        state->seed = seed;
+    }
+    return seed ^ RandU64FromSeed(++state->counter);
+}
+
+f64 RandF64FromState(RandState *state, f64 range_start, f64 range_end)
+{
+    return range_start + (range_end - range_start) * ((f64)(RandU64FromState(state) % RandMaxF64) / (f64)RandMaxF64);
+}
+
+////////////////////////////////
+//~ Seeded randomness
+
+/* Based on Jon Maiga's "mx3"
+ * https://jonkagstrom.com/mx3/mx3_rev2.html
+ */
+u64 RandU64FromSeed(u64 seed)
+{
+    seed = (seed ^ (seed >> 32)) * 0xbea225f9eb34556d;
+    seed = (seed ^ (seed >> 29)) * 0xbea225f9eb34556d;
+    seed = (seed ^ (seed >> 32)) * 0xbea225f9eb34556d;
+    seed = (seed ^ (seed >> 29));
+    return seed;
+}
+
+u64 RandU64FromSeeds(u64 seed_a, u64 seed_b)
+{
+    return RandU64FromSeed((seed_a * 3) + seed_b);
+}
+
+f64 RandF64FromSeed(u64 seed, f64 range_start, f64 range_end)
+{
+    return range_start + (range_end - range_start) * ((f64)(RandU64FromSeed(seed) % RandMaxF64) / (f64)RandMaxF64);
+}
diff --git a/src/meta/meta_base/meta_base_rand.h b/src/meta/meta_base/meta_base_rand.h
new file mode 100644
index 00000000..c2c79cb8
--- /dev/null
+++ b/src/meta/meta_base/meta_base_rand.h
@@ -0,0 +1,23 @@
+////////////////////////////////
+//~ Rand types
+
+Struct(RandState)
+{
+    u64 seed;  /* If a state's seed == 0 upon a call to a related function, it will be initialized using platform's true rng source */
+    u64 counter;
+};
+
+/* TODO: Use a value that gives good precision when dividing into range 0 -> 1 */
+#define RandMaxF64 U64Max
+
+////////////////////////////////
+//~ Rand operations
+
+//- Stateful randomness
+u64 RandU64FromState(RandState *state);
+f64 RandF64FromState(RandState *state, f64 range_start, f64 range_end);
+
+//- Seeded randomness
+u64 RandU64FromSeed(u64 seed);
+u64 RandU64FromSeeds(u64 seed_a, u64 seed_b);
+f64 RandF64FromSeed(u64 seed, f64 range_start, f64 range_end);
diff --git a/src/meta/meta_base/meta_base_string.c b/src/meta/meta_base/meta_base_string.c
index 5838c6d0..1a8df924 100644
--- a/src/meta/meta_base/meta_base_string.c
+++ b/src/meta/meta_base/meta_base_string.c
@@ -345,31 +345,6 @@ b32 EqString(String str1, String str2)
     return eq;
 }
 
-i32 CmpString(String str1, String str2)
-{
-    i32 result = 0;
-    for (u64 i = 0; i < MinU64(str1.len, str2.len); ++i)
-    {
-        result = str1.text[i] - str2.text[i];
-        if (result != 0)
-        {
-            break;
-        }
-    }
-    if (result == 0)
-    {
-        if (str1.len > str2.len)
-        {
-            result = str1.text[str2.len];
-        }
-        else if (str2.len > str1.len)
-        {
-            result = str2.text[str1.len];
-        }
-    }
-    return result;
-}
-
 //- Match
 
 b32 StringContains(String str, String substring)
@@ -636,7 +611,7 @@ String StringFormatV(Arena *arena, String fmt, va_list args)
     };
 }
 
-String _StringFormat(Arena *arena, String fmt, ...)
+String StringFormat_(Arena *arena, String fmt, ...)
 {
     va_list args;
     va_start(args, fmt);
diff --git a/src/meta/meta_base/meta_base_string.h b/src/meta/meta_base/meta_base_string.h
index 15ee69df..feea4f8e 100644
--- a/src/meta/meta_base/meta_base_string.h
+++ b/src/meta/meta_base/meta_base_string.h
@@ -91,7 +91,6 @@ StringArray SplitString(Arena *arena, String str, String delim);
 String IndentString(Arena *arena, String str, u32 indent);
 String LowerString(Arena *arena, String str);
 b32 EqString(String str1, String str2);
-i32 CmpString(String str1, String str2);
 b32 StringContains(String str, String substring);
 b32 StringStartsWith(String str, String substring);
 b32 StringEndsWith(String str, String substring);
@@ -127,9 +126,9 @@ String Trim(String s, String pattern);
 #define FmtEnd              (FmtArg) {.kind = FmtKind_End}
 
 //- Format functions
-#define StringF(arena, lit, ...) _StringFormat((arena), Lit(lit), __VA_ARGS__, FmtEnd)
-#define StringFormat(arena, fmt, ...) _StringFormat((arena), (fmt), __VA_ARGS__, FmtEnd)
-String _StringFormat(Arena *arena, String fmt, ...);
+#define StringF(arena, lit, ...) StringFormat_((arena), Lit(lit), __VA_ARGS__, FmtEnd)
+#define StringFormat(arena, fmt, ...) StringFormat_((arena), (fmt), __VA_ARGS__, FmtEnd)
+String StringFormat_(Arena *arena, String fmt, ...);
 String StringFormatV(Arena *arena, String fmt, va_list args);
 
 ////////////////////////////////
diff --git a/src/meta/meta_base/meta_base_win32/meta_base_win32.c b/src/meta/meta_base/meta_base_win32/meta_base_win32.c
index 0e889fa7..e86273b6 100644
--- a/src/meta/meta_base/meta_base_win32/meta_base_win32.c
+++ b/src/meta/meta_base/meta_base_win32/meta_base_win32.c
@@ -1,11 +1,5 @@
 W32_SharedState W32_shared_state = ZI;
 
-////////////////////////////////
-//~ Windows libs
-
-#pragma comment(lib, "kernel32")
-#pragma comment(lib, "user32")
-
 ////////////////////////////////
 //~ @hookdef OS startup hook
 
@@ -55,3 +49,11 @@ i16 ThreadId(void)
     W32_SharedState *g = &W32_shared_state;
     return (i16)(i64)TlsGetValue(g->tls_index);
 }
+
+////////////////////////////////
+//~ @hookdef Randomness hooks
+
+void TrueRand(String buffer)
+{
+    BCryptGenRandom(BCRYPT_RNG_ALG_HANDLE, (u8 *)buffer.text, buffer.len, 0);
+}
diff --git a/src/meta/meta_base/meta_base_win32/meta_base_win32.h b/src/meta/meta_base/meta_base_win32/meta_base_win32.h
index 67837b7b..5eb5cea8 100644
--- a/src/meta/meta_base/meta_base_win32/meta_base_win32.h
+++ b/src/meta/meta_base/meta_base_win32/meta_base_win32.h
@@ -1,3 +1,15 @@
+////////////////////////////////
+//~ Win32 libs
+
+#ifndef BCRYPT_RNG_ALG_HANDLE
+#define BCRYPT_RNG_ALG_HANDLE ((void *)0x00000081)
+u32 BCryptGenRandom(void *algorithm, u8 *buffer, u32 buffer_size, u32 flags);
+#endif
+
+#pragma comment(lib, "kernel32")
+#pragma comment(lib, "user32")
+#pragma comment(lib, "bcrypt")
+
 ////////////////////////////////
 //~ Shared state
 
diff --git a/src/meta/meta_os/meta_os.h b/src/meta/meta_os/meta_os.h
index 1d61566c..0f83c332 100644
--- a/src/meta/meta_os/meta_os.h
+++ b/src/meta/meta_os/meta_os.h
@@ -38,14 +38,17 @@ String OS_ReadEntireFile(Arena *arena, OS_File file);
 void OS_ClearWriteFile(OS_File file, String data);
 void OS_DirContentsFromFullPath(Arena *arena, StringList *list, String path);
 String OS_GetFullPath(Arena *arena, String path);
-b32 OS_FileOrDirExists(String path);
-b32 OS_FileExists(String path);
-b32 OS_DirExists(String path);
+u64 OS_LastWriteTimestampFromPath(String path);
 
 ////////////////////////////////
 //~ @hookdecl Directory helpers
 
+b32 OS_FileOrDirExists(String path);
+b32 OS_FileExists(String path);
+b32 OS_DirExists(String path);
 void OS_Mkdir(String path);
+void OS_RmDir(String path);
+void OS_Rm(String path);
 
 ////////////////////////////////
 //~ @hookdecl Shell operations
diff --git a/src/meta/meta_os/meta_os_win32/meta_os_win32.c b/src/meta/meta_os/meta_os_win32/meta_os_win32.c
index e5080bd1..c61b3aa2 100644
--- a/src/meta/meta_os/meta_os_win32/meta_os_win32.c
+++ b/src/meta/meta_os/meta_os_win32/meta_os_win32.c
@@ -1,9 +1,3 @@
-////////////////////////////////
-//~ Windows libs
-
-#pragma comment(lib, "kernel32")
-#pragma comment(lib, "user32")
-
 ////////////////////////////////
 //~ @hookdef Startup hook
 
@@ -118,17 +112,24 @@ String OS_GetFullPath(Arena *arena, String path)
     return res;
 }
 
-////////////////////////////////
-//~ @hookdef Directory helper hooks
-
-void OS_Mkdir(String path)
+u64 OS_LastWriteTimestampFromPath(String path)
 {
     TempArena scratch = BeginScratchNoConflict();
+    u64 result = 0;
+    WIN32_FILE_ATTRIBUTE_DATA a = ZI;
     wchar_t *path_wstr = WstrFromString(scratch.arena, path);
-    CreateDirectoryW(path_wstr, 0);
+    if (GetFileAttributesExW(path_wstr, GetFileExInfoStandard, &a))
+    {
+        result = ((ULONGLONG)a.ftLastWriteTime.dwHighDateTime << 32) |
+                  (ULONGLONG)a.ftLastWriteTime.dwLowDateTime;
+    }
     EndScratch(scratch);
+    return result;
 }
 
+////////////////////////////////
+//~ @hookdef Directory helper hooks
+
 b32 OS_FileOrDirExists(String path)
 {
     TempArena scratch = BeginScratchNoConflict();
@@ -156,6 +157,29 @@ b32 OS_DirExists(String path)
     return attributes != INVALID_FILE_ATTRIBUTES && (attributes & FILE_ATTRIBUTE_DIRECTORY);
 }
 
+void OS_Mkdir(String path)
+{
+    TempArena scratch = BeginScratchNoConflict();
+    wchar_t *path_wstr = WstrFromString(scratch.arena, path);
+    CreateDirectoryW(path_wstr, 0);
+    EndScratch(scratch);
+}
+
+void OS_RmDir(String dir)
+{
+    TempArena scratch = BeginScratchNoConflict();
+    wchar_t *path_wstr = WstrFromString(scratch.arena, dir);
+    RemoveDirectory(path_wstr);
+    EndScratch(scratch);
+}
+
+void OS_Rm(String path)
+{
+    TempArena scratch = BeginScratchNoConflict();
+    wchar_t *path_wstr = WstrFromString(scratch.arena, path);
+    DeleteFile(path_wstr);
+    EndScratch(scratch);
+}
 
 ////////////////////////////////
 //~ @hookdef Shell hooks
diff --git a/src/meta/meta_os/meta_os_win32/meta_os_win32.h b/src/meta/meta_os/meta_os_win32/meta_os_win32.h
index 10c83495..81de9b4f 100644
--- a/src/meta/meta_os/meta_os_win32/meta_os_win32.h
+++ b/src/meta/meta_os/meta_os_win32/meta_os_win32.h
@@ -1 +1,7 @@
 #include <stdlib.h>  /* _wfullpath */
+
+////////////////////////////////
+//~ Win32 libs
+
+#pragma comment(lib, "kernel32")
+#pragma comment(lib, "user32")
diff --git a/src/mp3/mp3_mmf/mp3_mmf.c b/src/mp3/mp3_mmf/mp3_mmf.c
index e951262c..2dc2ec33 100644
--- a/src/mp3/mp3_mmf/mp3_mmf.c
+++ b/src/mp3/mp3_mmf/mp3_mmf.c
@@ -1,19 +1,3 @@
-////////////////////////////////
-//~ Windows headers
-
-#pragma warning(push, 0)
-# include <uuids.h>
-# include <mfapi.h>
-# include <mfidl.h>
-# include <mfreadwrite.h>
-# include <Shlwapi.h>
-# include <objidl.h>
-#pragma warning(pop)
-
-#pragma comment(lib, "mfplat")
-#pragma comment(lib, "mfreadwrite")
-#pragma comment(lib, "shlwapi")
-
 ////////////////////////////////
 //~ Decode
 
diff --git a/src/mp3/mp3_mmf/mp3_mmf.h b/src/mp3/mp3_mmf/mp3_mmf.h
new file mode 100644
index 00000000..f73c5049
--- /dev/null
+++ b/src/mp3/mp3_mmf/mp3_mmf.h
@@ -0,0 +1,15 @@
+////////////////////////////////
+//~ Windows headers
+
+#pragma warning(push, 0)
+# include <uuids.h>
+# include <mfapi.h>
+# include <mfidl.h>
+# include <mfreadwrite.h>
+# include <Shlwapi.h>
+# include <objidl.h>
+#pragma warning(pop)
+
+#pragma comment(lib, "mfplat")
+#pragma comment(lib, "mfreadwrite")
+#pragma comment(lib, "shlwapi")
diff --git a/src/mp3/mp3_mmf/mp3_mmf.lay b/src/mp3/mp3_mmf/mp3_mmf.lay
index c9b3dec7..cf241bb4 100644
--- a/src/mp3/mp3_mmf/mp3_mmf.lay
+++ b/src/mp3/mp3_mmf/mp3_mmf.lay
@@ -1,4 +1,7 @@
 @Layer mp3_mmf
 
+//- Api
+@IncludeC mp3_mmf.h
+
 //- Impl
 @IncludeC mp3_mmf.c
diff --git a/src/platform/platform_win32/platform_win32.c b/src/platform/platform_win32/platform_win32.c
index 3d7de946..3ce84daf 100644
--- a/src/platform/platform_win32/platform_win32.c
+++ b/src/platform/platform_win32/platform_win32.c
@@ -1,19 +1,5 @@
 P_W32_SharedCtx P_W32_shared_ctx = ZI;
 
-////////////////////////////////
-//~ Win32 libs
-
-#pragma comment(lib, "kernel32")
-#pragma comment(lib, "user32")
-#pragma comment(lib, "shell32")
-#pragma comment(lib, "ole32")
-#pragma comment(lib, "winmm")
-#pragma comment(lib, "dwmapi")
-#pragma comment(lib, "bcrypt")
-#pragma comment(lib, "synchronization")
-#pragma comment(lib, "avrt")
-#pragma comment(lib, "ws2_32.lib")
-
 ////////////////////////////////
 //~ @hookdef Startup
 
diff --git a/src/platform/platform_win32/platform_win32.h b/src/platform/platform_win32/platform_win32.h
index 054fdfb3..3102cdd9 100644
--- a/src/platform/platform_win32/platform_win32.h
+++ b/src/platform/platform_win32/platform_win32.h
@@ -1,5 +1,5 @@
 ////////////////////////////////
-//~ Win32 headers
+//~ Win32 libs
 
 #pragma warning(push, 0)
 #  include <WinSock2.h>
@@ -9,11 +9,20 @@
 #  include <ShlObj_core.h>
 #  include <fileapi.h>
 #  include <dwmapi.h>
-#  include <bcrypt.h>
 #  include <avrt.h>
 #  include <shellapi.h>
 #pragma warning(pop)
 
+#pragma comment(lib, "kernel32")
+#pragma comment(lib, "user32")
+#pragma comment(lib, "shell32")
+#pragma comment(lib, "ole32")
+#pragma comment(lib, "winmm")
+#pragma comment(lib, "dwmapi")
+#pragma comment(lib, "synchronization")
+#pragma comment(lib, "avrt")
+#pragma comment(lib, "ws2_32.lib")
+
 ////////////////////////////////
 //~ Window types
 
diff --git a/src/playback/playback_wasapi/playback_wasapi.h b/src/playback/playback_wasapi/playback_wasapi.h
index fa0ea963..0553ed10 100644
--- a/src/playback/playback_wasapi/playback_wasapi.h
+++ b/src/playback/playback_wasapi/playback_wasapi.h
@@ -1,5 +1,5 @@
 ////////////////////////////////
-//~ Win32 headers
+//~ Win32 libs
 
 #pragma warning(push, 0)
 # include <initguid.h>
diff --git a/src/ttf/ttf_dwrite/ttf_dwrite.c b/src/ttf/ttf_dwrite/ttf_dwrite.c
index 7c42150d..de4206aa 100644
--- a/src/ttf/ttf_dwrite/ttf_dwrite.c
+++ b/src/ttf/ttf_dwrite/ttf_dwrite.c
@@ -3,12 +3,6 @@
 
 TTF_DW_SharedState TTF_DW_shared_state = ZI;
 
-////////////////////////////////
-//~ Win32 libs
-
-#pragma comment(lib, "dwrite")
-#pragma comment(lib, "gdi32")
-
 ////////////////////////////////
 //~ @hookdef Startup
 
diff --git a/src/ttf/ttf_dwrite/ttf_dwrite.h b/src/ttf/ttf_dwrite/ttf_dwrite.h
index 8f1ab709..04c4506a 100644
--- a/src/ttf/ttf_dwrite/ttf_dwrite.h
+++ b/src/ttf/ttf_dwrite/ttf_dwrite.h
@@ -1,3 +1,14 @@
+////////////////////////////////
+//~ Win32 libs
+
+#include <combaseapi.h>
+#include <dcommon.h>
+#include <initguid.h>
+#include <unknwn.h>
+
+#pragma comment(lib, "dwrite")
+#pragma comment(lib, "gdi32")
+
 ////////////////////////////////
 //~ DirectWrite types
 
@@ -5,12 +16,6 @@
  * https://github.com/mmozeiko/c_d2d_dwrite/blob/main/cdwrite.h
  */
 
-//- Windows headers
-#include <combaseapi.h>
-#include <dcommon.h>
-#include <initguid.h>
-#include <unknwn.h>
-
 //- GUIDs
 DEFINE_GUID(IID_IDWriteFactory5,    0x958db99a, 0xbe2a, 0x4f09, 0xaf, 0x7d, 0x65, 0x18, 0x98, 0x03, 0xd1, 0xd3);