Fix MockFileSystem temp path mismatch in write-scope methods

MockFileSystem on non-Windows returns a hardcoded Unix-ified path ('/temp/')
for GetTempPath() — it unixifies 'C:\temp' rather than calling
System.IO.Path.GetTempPath(). This diverges from the real API which reads
TMPDIR. AllowedSpecialFolder.Temp in the ValidationContext uses the real
System.IO.Path.GetTempPath() (resolves to '/tmp/' on standard Linux), creating
a mismatch: the scope allows '/tmp/' but the mock FS creates staging paths
at '/temp/zzyysk35.wbk'.

Fix: ScopeCurrentWorkingDirectoryForWrite and ScopeSourceDirectoryForWrite
now call inner.Path.GetTempPath() on non-Windows and add the result as an
explicit scope root alongside AllowedSpecialFolders.Temp. This covers both
the real OS temp ('/tmp/' via AllowedSpecialFolders) and the mock's hardcoded
path ('/temp/' via the explicit root), without relaxing permissions on Windows
where MockFileSystem temp is consistent with the real API.

Co-Authored-By: Claude Sonnet 4.6 (1M context) <[email protected]>

Author: Mpdreamz

src/Elastic.Documentation.Configuration/FileSystemFactory.cs

@@ -101,13 +101,36 @@ public static ScopedFileSystem ScopeCurrentWorkingDirectory(IFileSystem inner, I
 		});
 	}
 
+	// Builds write options that include AllowedSpecialFolders.Temp PLUS the inner FS's own
+	// GetTempPath() as an explicit root. This is necessary because MockFileSystem on non-Windows
+	// returns a hardcoded Unix-ified path ("/temp/") instead of System.IO.Path.GetTempPath(),
+	// causing a mismatch with the AllowedSpecialFolder.Temp validation which uses the real API.
+	private static ScopedFileSystemOptions BuildWriteOptions(IFileSystem inner, params string[] roots)
+	{
+		var allRoots = roots.ToList();
+		if (!OperatingSystem.IsWindows())
+		{
+			// Cover MockFileSystem's unixified hardcoded temp path
+			var innerTemp = inner.Path.GetTempPath().TrimEnd(Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar);
+			if (!string.IsNullOrEmpty(innerTemp) && !allRoots.Contains(innerTemp, StringComparer.OrdinalIgnoreCase))
+				allRoots.Add(innerTemp);
+		}
+		return new ScopedFileSystemOptions([.. allRoots])
+		{
+			AllowedHiddenFolderNames = new HashSet<string>(StringComparer.OrdinalIgnoreCase) { ".artifacts" },
+			AllowedHiddenFileNames = new HashSet<string>(StringComparer.OrdinalIgnoreCase) { ".doc.state" },
+			AllowedSpecialFolders = AllowedSpecialFolder.Temp
+		};
+	}
+
 	/// <summary>
 	/// Scopes <paramref name="inner"/> to <see cref="Paths.WorkingDirectoryRoot"/> and
 	/// <see cref="Paths.ApplicationData"/> for writing (.git not allowed). Use when
 	/// the inner FS writes into the working-directory tree.
 	/// </summary>
 	public static ScopedFileSystem ScopeCurrentWorkingDirectoryForWrite(IFileSystem inner) =>
-		new(inner, WorkingDirectoryWriteOptions);
+		new(inner, BuildWriteOptions(
+			inner, Paths.WorkingDirectoryRoot.FullName, Paths.ApplicationData.FullName));
 
 	/// <summary>
 	/// Scopes <paramref name="inner"/> to an explicit <paramref name="sourceRoot"/> and
@@ -128,12 +151,7 @@ public static ScopedFileSystem ScopeSourceDirectory(IFileSystem inner, string so
 	/// of <see cref="ScopeSourceDirectory(IFileSystem, string)"/>.
 	/// </summary>
 	public static ScopedFileSystem ScopeSourceDirectoryForWrite(IFileSystem inner, string sourceRoot) =>
-		new(inner, new ScopedFileSystemOptions([sourceRoot, Paths.ApplicationData.FullName])
-		{
-			AllowedHiddenFolderNames = new HashSet<string>(StringComparer.OrdinalIgnoreCase) { ".artifacts" },
-			AllowedHiddenFileNames = new HashSet<string>(StringComparer.OrdinalIgnoreCase) { ".doc.state" },
-			AllowedSpecialFolders = AllowedSpecialFolder.Temp
-		});
+		new(inner, BuildWriteOptions(inner, sourceRoot, Paths.ApplicationData.FullName));
 
 	/// <summary>
 	/// Creates a read <see cref="ScopedFileSystem"/> scoped to the git root of

tests-integration/Elastic.Assembler.IntegrationTests/DocsSyncTests.cs

@@ -40,7 +40,7 @@ public async Task TestPlan()
 			{ "docs/update.md", new MockFileData("# Existing Document") },
 		}, new MockFileSystemOptions
 		{
-			CurrentDirectory = Path.Join(Paths.WorkingDirectoryRoot.FullName, ".artifacts", "assembly")
+			CurrentDirectory = Path.Join(Paths.WorkingDirectoryRoot.FullName, ".artifacts", "assembly"),
 		});
 
 		var configurationContext = TestHelpers.CreateConfigurationContext(fileSystem);
@@ -181,7 +181,7 @@ bool valid
 		var mockS3Client = A.Fake<IAmazonS3>();
 		var fileSystem = new MockFileSystem(new MockFileSystemOptions
 		{
-			CurrentDirectory = Path.Join(Paths.WorkingDirectoryRoot.FullName, ".artifacts", "assembly")
+			CurrentDirectory = Path.Join(Paths.WorkingDirectoryRoot.FullName, ".artifacts", "assembly"),
 		});
 		foreach (var i in Enumerable.Range(0, localFiles))
 			fileSystem.AddFile($"docs/file-{i}.md", new MockFileData($"# Local Document {i}"));
@@ -235,7 +235,7 @@ public async Task TestApply()
 			{ "docs/update.md", new MockFileData("# Existing Document") },
 		}, new MockFileSystemOptions
 		{
-			CurrentDirectory = Path.Join(Paths.WorkingDirectoryRoot.FullName, ".artifacts", "assembly")
+			CurrentDirectory = Path.Join(Paths.WorkingDirectoryRoot.FullName, ".artifacts", "assembly"),
 		});
 		var configurationContext = TestHelpers.CreateConfigurationContext(fileSystem);
 		var config = AssemblyConfiguration.Create(configurationContext.ConfigurationFileProvider);