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.Domain/PathRules.cs

@@ -0,0 +1,202 @@
+namespace Explorer.Domain;
+
+public static class PathRules
+{
+    public const string ExtendedPrefix = @"\\?\";
+    public const string ExtendedUncPrefix = @"\\?\UNC\";
+
+    public static string ToExtended(string path)
+    {
+        if (string.IsNullOrWhiteSpace(path))
+        {
+            return path;
+        }
+
+        if (path.StartsWith(ExtendedPrefix, StringComparison.Ordinal))
+        {
+            return path;
+        }
+
+        if (path.StartsWith(@"\\", StringComparison.Ordinal))
+        {
+            return ExtendedUncPrefix + path[2..];
+        }
+
+        return ExtendedPrefix + path;
+    }
+
+    public static string FromExtended(string path)
+    {
+        if (path.StartsWith(ExtendedUncPrefix, StringComparison.OrdinalIgnoreCase))
+        {
+            return @"\\" + path[ExtendedUncPrefix.Length..];
+        }
+
+        if (path.StartsWith(ExtendedPrefix, StringComparison.Ordinal))
+        {
+            return path[ExtendedPrefix.Length..];
+        }
+
+        return path;
+    }
+
+    public static bool IsUnc(string path)
+    {
+        var p = FromExtended(path);
+        return p.StartsWith(@"\\", StringComparison.Ordinal);
+    }
+
+    public static string NormalizeDirectorySeparators(string path)
+        => path.Replace('/', '\\');
+
+    public static string Combine(string root, string relative)
+    {
+        root = FromExtended(root).TrimEnd('\\');
+        relative = relative.Replace('/', '\\').TrimStart('\\');
+        if (string.IsNullOrEmpty(relative))
+        {
+            return EnsureDirectoryTrailingSlashIfRoot(root);
+        }
+
+        return root + "\\" + relative;
+    }
+
+    public static string MakeRelative(string root, string fullPath)
+    {
+        var r = FromExtended(root).TrimEnd('\\');
+        var f = FromExtended(fullPath).TrimEnd('\\');
+        if (f.Equals(r, StringComparison.OrdinalIgnoreCase))
+        {
+            return string.Empty;
+        }
+
+        if (f.StartsWith(r + "\\", StringComparison.OrdinalIgnoreCase))
+        {
+            return f[(r.Length + 1)..];
+        }
+
+        return f;
+    }
+
+    public static string CanonicalUncRoot(string path)
+    {
+        var p = FromExtended(path).TrimEnd('\\');
+        if (!p.StartsWith(@"\\", StringComparison.Ordinal))
+        {
+            return p;
+        }
+
+        var parts = p[2..].Split('\\', StringSplitOptions.RemoveEmptyEntries);
+        if (parts.Length < 2)
+        {
+            return @"\\" + p[2..].ToLowerInvariant();
+        }
+
+        return @"\\" + parts[0].ToLowerInvariant() + "\\" + parts[1];
+    }
+
+    public static string Parent(string path)
+    {
+        var p = FromExtended(path).TrimEnd('\\');
+        if (p.Length >= 2 && p[1] == ':' && p.Length <= 3)
+        {
+            return p.Length == 2 ? p + "\\" : p + (p.EndsWith('\\') ? "" : "\\");
+        }
+
+        if (IsUnc(p))
+        {
+            var root = CanonicalUncRoot(p);
+            if (p.Equals(root, StringComparison.OrdinalIgnoreCase))
+            {
+                return root;
+            }
+        }
+
+        var idx = p.LastIndexOf('\\');
+        if (idx <= 0)
+        {
+            return p;
+        }
+
+        if (idx == 2 && p[1] == ':')
+        {
+            return p[..3];
+        }
+
+        return p[..idx];
+    }
+
+    public static bool IsDriveRoot(string path)
+    {
+        var p = FromExtended(path).TrimEnd('\\');
+        return p.Length == 2 && p[1] == ':';
+    }
+
+    public static string EnsureDirectoryTrailingSlashIfRoot(string path)
+    {
+        var p = FromExtended(path);
+        if (p.Length == 2 && p[1] == ':')
+        {
+            return p + "\\";
+        }
+
+        return p;
+    }
+
+    public static string GetFileName(string path)
+    {
+        var p = FromExtended(path).TrimEnd('\\');
+        var idx = p.LastIndexOf('\\');
+        return idx < 0 ? p : p[(idx + 1)..];
+    }
+
+    public static string JoinDisplay(string? root, string pathRel)
+    {
+        if (string.IsNullOrWhiteSpace(root))
+        {
+            return pathRel;
+        }
+
+        return string.IsNullOrWhiteSpace(pathRel) ? EnsureDirectoryTrailingSlashIfRoot(root) : Combine(root, pathRel);
+    }
+
+    public static string ShortenDisplay(string path, int maxChars = 64)
+    {
+        var p = FromExtended(path);
+        if (p.Length <= maxChars)
+        {
+            return p;
+        }
+
+        var unc = IsUnc(p);
+        var parts = p.TrimEnd('\\').Split('\\', StringSplitOptions.RemoveEmptyEntries);
+        if (parts.Length <= 2)
+        {
+            return p;
+        }
+
+        string prefix;
+        var start = 0;
+        if (unc)
+        {
+            prefix = @"\\" + parts[0] + "\\" + parts[1];
+            start = 2;
+        }
+        else
+        {
+            prefix = parts.Length > 2 ? parts[0] + "\\" + parts[1] : parts[0];
+            start = parts.Length > 2 ? 2 : 1;
+        }
+
+        var leaf = parts[^1];
+        var parent = parts.Length - 1 > start ? parts[^2] + "\\" + leaf : leaf;
+        var candidate = prefix + @"\…\" + parent;
+        if (candidate.Length <= maxChars)
+        {
+            return candidate;
+        }
+
+        candidate = prefix + @"\…\" + leaf;
+        return candidate.Length <= maxChars ? candidate : prefix + @"\…";
+    }
+}