treat empty mkw save as missing

first-run format zero-fills rksys.dat before any real save; a quit before
the first save left an all-zero file that read back as corrupt and trapped
the user in a delete/recreate loop. read opens now treat an all-zero
rksys.dat as absent (a real save always begins with the RKSD0006 header),
so the game recreates it from scratch. also ignore native build output.

.gitignore

@@ -26,6 +26,8 @@ Code.pul
 /build/
 /build-*/
 /native-build/
+/native-build-macos/
+/local-products/
 /dist/
 /out/
 [Bb]in/

runtime/src/hle/storage/nand_api.cpp

@@ -93,6 +93,9 @@ extern "C" int32_t NANDOpen_HLE(uint32_t pathPtr, uint32_t fileInfoPtr, uint32_t
 
     const std::filesystem::path hostPath = TranslateNandPath(path);
 
+    if (NandIgnoreUninitializedSaveRead("NANDOpen", hostPath, mode))
+        return NAND_RESULT_NOEXISTS;
+
     // Existing-file write opens go through a shadow copy seeded from the original, so a
     // crash between NANDWrite and NANDClose cannot leave a torn file (the game patches
     // sub-ranges, e.g. ghost saves at a non-zero offset). New files still create in place.
@@ -136,10 +139,7 @@ extern "C" int32_t NANDOpen_HLE(uint32_t pathPtr, uint32_t fileInfoPtr, uint32_t
         }
     }
 
-    const char* fopenMode = "rb";
-    if (mode == 1) fopenMode = "rb";
-    else if (mode == 2) fopenMode = "r+b";
-    else if (mode == 3) fopenMode = "r+b";
+    const char* fopenMode = (mode == 2 || mode == 3) ? "r+b" : "rb";
     
     FILE* file = NandFopen(hostPath, fopenMode);
     if (!file && mode >= 2) {

runtime/src/hle/storage/nand_async.cpp

@@ -411,6 +411,8 @@ extern "C" int32_t NANDSafeOpen_HLE(uint32_t pathPtr, uint32_t fileInfoPtr, uint
     if (mode == 1) {
         // Read-only safe open reads the original in place; the library builds no scratch
         // copy for this case.
+        if (NandIgnoreUninitializedSaveRead("NANDSafeOpen", hostPath, mode))
+            return NAND_RESULT_NOEXISTS;
         FILE* file = NandFopen(hostPath, "rb");
         if (!file && IsFaceLibResourcePath(path) && SeedFaceLibResource(hostPath)) {
             file = NandFopen(hostPath, "rb");

runtime/src/hle/storage/nand_fs.cpp

@@ -411,6 +411,39 @@ bool IsFaceLibResourcePath(const char* path) {
     return std::strcmp(path, "/shared2/menu/FaceLib/RFL_Res.dat") == 0;
 }
 
+bool NandSystemSaveIsUninitialized(const std::filesystem::path& hostPath) {
+    if (!IsNandSystemSavePath(hostPath))
+        return false;
+
+    std::error_code ec;
+    if (!std::filesystem::is_regular_file(hostPath, ec) || ec)
+        return false;
+
+    std::ifstream in(hostPath, std::ios::binary);
+    if (!in)
+        return false;
+
+    char block[4096];
+    while (in) {
+        in.read(block, sizeof(block));
+        const std::streamsize got = in.gcount();
+
+        for (std::streamsize i = 0; i < got; ++i)
+            if (block[i] != 0)
+                return false;
+    }
+    return true;
+}
+
+bool NandIgnoreUninitializedSaveRead(const char* who,
+                                     const std::filesystem::path& hostPath, int mode) {
+    if (mode != 1 || !NandSystemSaveIsUninitialized(hostPath))
+        return false;
+    LogNandWarning(who, "ignoring uninitialized system save '%s' (no save committed yet)",
+                   HostPathText(hostPath).c_str());
+    return true;
+}
+
 // Create directories recursively
 bool CreateDirectoryPath(const std::filesystem::path& path) {
     if (path.empty()) {

runtime/src/hle/storage/nand_internal.h

@@ -56,6 +56,25 @@ constexpr uint32_t kNandTitleIdLo = 0x524D4350; // "RMCP" fallback
 void LogNandError(const char* func, const char* fmt, ...);
 void LogNandWarning(const char* func, const char* fmt, ...);
 
+// The Mario Kart Wii system save (rksys.dat) and its ".nandsafe.tmp" write shadows.
+inline bool IsNandSystemSavePath(const std::filesystem::path& path) {
+    const std::string name = path.filename().string();
+    return name == "rksys.dat" || name.rfind("rksys.dat", 0) == 0;
+}
+
+// True when a system save exists on the host but holds no committed save yet: the game
+// zero-fills rksys.dat during its first-run "format save data" step and only writes the
+// real database (which always begins with the RKSD0006 header) once it actually saves.
+// An all-zero file therefore contains nothing worth loading; read it as absent so the
+// game recreates its save instead of entering the corrupt-save recovery loop.
+bool NandSystemSaveIsUninitialized(const std::filesystem::path& hostPath);
+
+// Read-open helper: logs and returns true when a read of this system save should see
+// "no save". Centralizes the mode == 1 guard and warning so the NAND, NANDSafe and IOS
+// open paths share one branch and message.
+bool NandIgnoreUninitializedSaveRead(const char* who, const std::filesystem::path& hostPath,
+                                     int mode);
+
 // ============================================================================
 // File Descriptor Management
 // ============================================================================

runtime/src/hle/storage/nand_isfs.cpp

@@ -391,6 +391,9 @@ extern "C" int32_t NAND_IOS_Open_HLE(uint32_t pathPtr, uint32_t mode) {
     
     // It's a NAND file path
     const std::filesystem::path hostPath = TranslateNandPath(path);
+
+    if (NandIgnoreUninitializedSaveRead("IOS_Open", hostPath, mode))
+        return ISFS_ENOENT;
     
     // Seed FaceLib resources before the existence check so every open mode can
     // still find them on a fresh managed NAND.