Add Explorer Workbench with hierarchical, off-UI Storage analysis.

Storage queries run in the background with cancellation and covering indexes so switching views no longer freezes the UI.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/Explorer.Windows/CloudFilesNative.cs

@@ -0,0 +1,160 @@
+using System.Runtime.InteropServices;
+using Explorer.Domain;
+
+namespace Explorer.Windows;
+
+public static partial class CloudFilesNative
+{
+    public const uint PlaceholderNone = 0;
+    public const uint Placeholder = 0x1;
+    public const uint PlaceholderSyncRoot = 0x2;
+    public const uint PlaceholderInSync = 0x8;
+    public const uint PlaceholderPartial = 0x10;
+    public const uint PlaceholderPartiallyOnDisk = 0x20;
+    public const uint PlaceholderInvalid = 0xFFFFFFFF;
+
+    public const int PinUnspecified = 0;
+    public const int PinPinned = 1;
+    public const int PinUnpinned = 2;
+    public const int PinExcluded = 3;
+    public const int PinInherit = 4;
+
+    public static nint OpenNoRecall(string path)
+        => NativeMethods.CreateFile(
+            PathRules.ToExtended(path),
+            NativeMethods.FileReadAttributes,
+            NativeMethods.FileShareRead | NativeMethods.FileShareWrite | NativeMethods.FileShareDelete,
+            0,
+            NativeMethods.OpenExisting,
+            NativeMethods.SafeOpenFlags,
+            0);
+
+    public static bool IsInvalid(nint handle)
+        => handle == nint.Zero || handle == new nint(-1);
+
+    public static long? TryGetAllocatedSize(string path)
+    {
+        var handle = OpenNoRecall(path);
+        if (IsInvalid(handle))
+        {
+            return null;
+        }
+
+        try
+        {
+            return TryGetAllocatedSize(handle);
+        }
+        finally
+        {
+            NativeMethods.CloseHandle(handle);
+        }
+    }
+
+    public static long? TryGetAllocatedSize(nint handle)
+    {
+        var size = Marshal.SizeOf<FileStandardInfo>();
+        var buffer = Marshal.AllocHGlobal(size);
+        try
+        {
+            if (!NativeMethods.GetFileInformationByHandleEx(handle, NativeMethods.FileStandardInfo, buffer, (uint)size))
+            {
+                return null;
+            }
+
+            var info = Marshal.PtrToStructure<FileStandardInfo>(buffer);
+            return info.AllocationSize;
+        }
+        catch
+        {
+            return null;
+        }
+        finally
+        {
+            Marshal.FreeHGlobal(buffer);
+        }
+    }
+
+    public static uint? TryGetPlaceholderState(int attributes, int reparseTag)
+    {
+        try
+        {
+            return CfGetPlaceholderStateFromAttributeTag((uint)attributes, (uint)reparseTag);
+        }
+        catch (DllNotFoundException)
+        {
+            return null;
+        }
+        catch (EntryPointNotFoundException)
+        {
+            return null;
+        }
+    }
+
+    public static bool TrySetPinState(string path, int pinState)
+    {
+        var handle = OpenNoRecall(path);
+        if (IsInvalid(handle))
+        {
+            return false;
+        }
+
+        try
+        {
+            return CfSetPinState(handle, pinState, 0, nint.Zero) == 0;
+        }
+        catch (DllNotFoundException)
+        {
+            return false;
+        }
+        catch (EntryPointNotFoundException)
+        {
+            return false;
+        }
+        finally
+        {
+            NativeMethods.CloseHandle(handle);
+        }
+    }
+
+    public static bool IsCloudSyncRoot(string path)
+    {
+        try
+        {
+            uint returned = 0;
+            var hr = CfGetSyncRootInfoByPath(path, 0, nint.Zero, 0, ref returned);
+            const int insufficientBuffer = unchecked((int)0x8007007A);
+            return hr == 0 || (hr == insufficientBuffer && returned > 0);
+        }
+        catch (DllNotFoundException)
+        {
+            return false;
+        }
+        catch (EntryPointNotFoundException)
+        {
+            return false;
+        }
+        catch
+        {
+            return false;
+        }
+    }
+
+    [LibraryImport("cldapi.dll")]
+    private static partial uint CfGetPlaceholderStateFromAttributeTag(uint fileAttributes, uint reparseTag);
+
+    [DllImport("cldapi.dll", ExactSpelling = true)]
+    private static extern int CfSetPinState(nint fileHandle, int pinState, uint pinFlags, nint overlapped);
+
+    [DllImport("cldapi.dll", CharSet = CharSet.Unicode, ExactSpelling = true)]
+    private static extern int CfGetSyncRootInfoByPath(string filePath, int infoClass, nint infoBuffer, uint infoBufferLength, ref uint returnedLength);
+
+    [StructLayout(LayoutKind.Sequential)]
+    private struct FileStandardInfo
+    {
+        public long AllocationSize;
+        public long EndOfFile;
+        public uint NumberOfLinks;
+        public byte DeletePending;
+        public byte Directory;
+    }
+}