[#14] Address Copilot review follow-ups

UnityFileSystem.Tests/UnityFileSystemTests.cs

@@ -27,7 +27,10 @@ public static void WithCopy(string source, string fileName, Action<string> test)
         }
         finally
         {
-            Directory.Delete(dir, true);
+            // Best-effort cleanup: a delete failure (e.g. a handle not yet released on Windows)
+            // must not mask a test failure thrown from the block above.
+            try { Directory.Delete(dir, true); }
+            catch { /* ignore */ }
         }
     }
 }

UnityFileSystem/DllWrapper.cs

@@ -196,9 +196,10 @@ public static class DllWrapper
     public static extern ReturnCode GetArchiveNodeCount(UnityArchiveHandle handle, out int count);
 
     // Strings returned from native (here and in the other StringBuilder-based calls) come back as
-    // UTF-8 bytes but are marshalled as the system ANSI code page, so only ASCII round-trips correctly.
-    // These are internal archive/serialized-file names, which Unity keeps ASCII, so it's not an issue in
-    // practice. Input paths, by contrast, are marshalled as UTF-8 (LPUTF8Str) to support non-ASCII paths.
+    // UTF-8 bytes but are marshalled as the system ANSI code page. On Windows that's a lossy code page,
+    // so only ASCII round-trips correctly (on macOS/Linux it happens to be UTF-8). These are internal
+    // archive/serialized-file names, which Unity keeps ASCII, so it's not an issue in practice. Input
+    // paths, by contrast, are marshalled as UTF-8 (LPUTF8Str) to support non-ASCII paths on all platforms.
     [DllImport("UnityFileSystemApi",
         CallingConvention = CallingConvention.Cdecl,
         EntryPoint = "UFS_GetArchiveNode")]
@@ -215,14 +216,19 @@ private static extern ReturnCode CreateArchiveNative(IntPtr[] sourceFiles, IntPt
     public static ReturnCode CreateArchive(string[] sourceFiles, string[] aliases, bool[] isSerializedFile, int count,
         string archiveFile, CompressionType compression, out int crc)
     {
-        var sourcePtrs = new IntPtr[sourceFiles.Length];
-        var aliasPtrs = new IntPtr[aliases.Length];
+        if (count < 0 || count > sourceFiles.Length || count > aliases.Length || count > isSerializedFile.Length)
+            throw new ArgumentOutOfRangeException(nameof(count));
+
+        // Marshal only the first `count` entries, since that's all the native call consumes.
+        var sourcePtrs = new IntPtr[count];
+        var aliasPtrs = new IntPtr[count];
         try
         {
-            for (int i = 0; i < sourceFiles.Length; ++i)
+            for (int i = 0; i < count; ++i)
+            {
                 sourcePtrs[i] = Marshal.StringToCoTaskMemUTF8(sourceFiles[i]);
-            for (int i = 0; i < aliases.Length; ++i)
                 aliasPtrs[i] = Marshal.StringToCoTaskMemUTF8(aliases[i]);
+            }
 
             return CreateArchiveNative(sourcePtrs, aliasPtrs, isSerializedFile, count, archiveFile, compression, out crc);
         }