feat(all): Write consistent line endings, configurable via line-endings

CHANGELOG.md

@@ -7,6 +7,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- `line-endings` option (`--line-endings`) to choose between `crlf` (default) and `lf` in generated files
+
+### Fixed
+
+- Generated files no longer mix CRLF and LF line endings on macOS and Linux
+
 ## [0.22.1] - 2026-08-23
 
 ### Fixed

README.md

@@ -85,8 +85,13 @@ dotnet-config tool for viewing and changing configuration similar to how
     root = "~/api"
     generate-api-clients = true
     build-zod-schemas = true
+    line-endings = "lf" # Defaults to "crlf"
 ```
 
+Generated files always use the same line endings, regardless of the OS
+TypeContractor runs on. The default is `crlf`; set `line-endings = "lf"` (or
+pass `--line-endings lf`) to use Unix line endings instead.
+
 ## Run manually
 
 Get an instance of `Contractor` and call `contractor.Build();`

TypeContractor.Tests/TypeScript/ApiClientWriterTests.cs

@@ -52,6 +52,45 @@ public void Can_Write_Basic_Client()
 			.And.Contain("return await response.json();");
 	}
 
+	[Fact]
+	public void Defaults_To_Crlf_Line_Endings()
+	{
+		// Arrange
+		var apiClient = new ApiClient("TestClient", "TestController", "test", null);
+		apiClient.AddEndpoint(new ApiClientEndpoint("getLatestId", "latest", EndpointMethod.GET, typeof(Guid), typeof(Guid), false, [], null));
+
+		// Act
+		var result = Sut.Write(apiClient, [], _converter, false, _templateFn, Casing.Pascal);
+
+		// Assert
+		var text = File.ReadAllText(result);
+		text.Should().Contain("\r\n");
+		text.Replace("\r\n", "", StringComparison.Ordinal).Should()
+			.NotContain("\r")
+			.And.NotContain("\n");
+	}
+
+	[Theory]
+	[InlineData(LineEndings.Crlf, "\r\n")]
+	[InlineData(LineEndings.Lf, "\n")]
+	public void Uses_Configured_Line_Endings(LineEndings lineEndings, string newLine)
+	{
+		// Arrange
+		var apiClient = new ApiClient("TestClient", "TestController", "test", null);
+		apiClient.AddEndpoint(new ApiClientEndpoint("getLatestId", "latest", EndpointMethod.GET, typeof(Guid), typeof(Guid), false, [], null));
+		var sut = new ApiClientWriter(_configuration.OutputPath, "~", lineEndings);
+
+		// Act
+		var result = sut.Write(apiClient, [], _converter, false, _templateFn, Casing.Pascal);
+
+		// Assert
+		var text = File.ReadAllText(result);
+		text.Should().Contain(newLine);
+		text.Replace(newLine, "", StringComparison.Ordinal).Should()
+			.NotContain("\r")
+			.And.NotContain("\n");
+	}
+
 	[Fact]
 	public void Strips_Trailing_Slash()
 	{

TypeContractor.Tests/TypeScript/TypeScriptWriterTests.cs

@@ -49,6 +49,43 @@ public void Can_Write_Simple_Types()
 			.And.Contain("someObject: any;");
 	}
 
+	[Fact]
+	public void Defaults_To_Crlf_Line_Endings()
+	{
+		// Arrange
+		var outputTypes = BuildOutputTypes(typeof(SimpleTypes));
+
+		// Act
+		var result = Sut.Write(outputTypes.First(), outputTypes, true);
+
+		// Assert
+		var text = File.ReadAllText(result);
+		text.Should().Contain("\r\n");
+		text.Replace("\r\n", "", StringComparison.Ordinal).Should()
+			.NotContain("\r")
+			.And.NotContain("\n");
+	}
+
+	[Theory]
+	[InlineData(LineEndings.Crlf, "\r\n")]
+	[InlineData(LineEndings.Lf, "\n")]
+	public void Uses_Configured_Line_Endings(LineEndings lineEndings, string newLine)
+	{
+		// Arrange
+		var outputTypes = BuildOutputTypes(typeof(SimpleTypes));
+		var sut = new TypeScriptWriter(_configuration.OutputPath, lineEndings);
+
+		// Act
+		var result = sut.Write(outputTypes.First(), outputTypes, true);
+
+		// Assert
+		var text = File.ReadAllText(result);
+		text.Should().Contain(newLine);
+		text.Replace(newLine, "", StringComparison.Ordinal).Should()
+			.NotContain("\r")
+			.And.NotContain("\n");
+	}
+
 	[Fact]
 	public void Can_Write_Generic_Types()
 	{

TypeContractor.Tool/Generator.cs

@@ -23,6 +23,7 @@ internal class Generator
 	private readonly bool _generateApiClients;
 	private readonly string _apiClientTemplate;
 	private readonly Casing? _casing;
+	private readonly LineEndings? _lineEndings;
 
 	public Generator(string assemblyPath,
 					 string[] alsoLookIn,
@@ -38,7 +39,8 @@ public Generator(string assemblyPath,
 					 bool buildZodSchemas,
 					 bool generateApiClients,
 					 string apiClientTemplate,
-					 Casing? casing)
+					 Casing? casing,
+					 LineEndings? lineEndings)
 	{
 		_assemblyPath = assemblyPath;
 		_alsoLookIn = alsoLookIn;
@@ -55,6 +57,7 @@ public Generator(string assemblyPath,
 		_generateApiClients = generateApiClients;
 		_apiClientTemplate = apiClientTemplate;
 		_casing = casing;
+		_lineEndings = lineEndings;
 	}
 
 	public Task<int> Execute(CancellationToken cancellationToken)
@@ -239,6 +242,9 @@ private Contractor GenerateContractor(Dictionary<Assembly, HashSet<Type>> typesT
 		if (_casing is not null)
 			configuration = configuration.SetCasing(_casing.Value);
 
+		if (_lineEndings is not null)
+			configuration = configuration.SetLineEndings(_lineEndings.Value);
+
 		return Contractor.WithConfiguration(configuration);
 	}
 }

TypeContractor.Tool/Program.cs

@@ -106,6 +106,12 @@
 	Description = "Casing to use for generated file names",
 };
 
+var lineEndingsOptions = new Option<LineEndings>("--line-endings")
+{
+	DefaultValueFactory = (arg) => config.GetEnum("line-endings", LineEndings.Crlf),
+	Description = "Line endings to use in generated files. Either 'crlf' (default) or 'lf'",
+};
+
 rootCommand.Options.Add(assemblyOption);
 rootCommand.Options.Add(extraAssemblyOptions);
 rootCommand.Options.Add(outputOption);
@@ -122,6 +128,7 @@
 rootCommand.Options.Add(generateApiClientsOptions);
 rootCommand.Options.Add(apiClientsTemplateOptions);
 rootCommand.Options.Add(casingOptions);
+rootCommand.Options.Add(lineEndingsOptions);
 
 apiClientsTemplateOptions.Validators.Add(result =>
 {
@@ -161,6 +168,7 @@
 	var generateApiClientsValue = parseResult.GetValue(generateApiClientsOptions);
 	var apiClientsTemplateValue = parseResult.GetValue(apiClientsTemplateOptions)!;
 	var casingValue = parseResult.GetValue(casingOptions);
+	var lineEndingsValue = parseResult.GetValue(lineEndingsOptions);
 
 	Log.Instance = new ConsoleLogger(logLevelValue);
 	var generator = new Generator(assemblyOptionValue,
@@ -177,7 +185,8 @@
 								  buildZodSchemasValue,
 								  generateApiClientsValue,
 								  apiClientsTemplateValue,
-								  casingValue);
+								  casingValue,
+								  lineEndingsValue);
 
 	return await generator.Execute(cancellationToken);
 });

TypeContractor/Contractor.cs

@@ -56,7 +56,7 @@ public int Build(MetadataLoadContext? metadataLoadContext = null, bool smartClea
 		var allTypes = new List<OutputType>();
 
 		var converter = new TypeScriptConverter(Configuration, metadataLoadContext);
-		var writer = new TypeScriptWriter(Configuration.OutputPath);
+		var writer = new TypeScriptWriter(Configuration.OutputPath, Configuration.LineEndings);
 
 		foreach (var (assemblyName, assemblyPath) in Configuration.Assemblies)
 		{
@@ -134,7 +134,7 @@ public int Build(MetadataLoadContext? metadataLoadContext = null, bool smartClea
 			}
 
 			var templateFn = Handlebars.Compile(template);
-			var apiWriter = new ApiClientWriter(Configuration.OutputPath, Configuration.RelativeRoot);
+			var apiWriter = new ApiClientWriter(Configuration.OutputPath, Configuration.RelativeRoot, Configuration.LineEndings);
 			foreach (var client in Configuration.ApiClients)
 			{
 				try

TypeContractor/Helpers/LineEndingHelpers.cs

@@ -0,0 +1,23 @@
+using System.Text.RegularExpressions;
+
+namespace TypeContractor.Helpers;
+
+internal static partial class LineEndingHelpers
+{
+	[GeneratedRegex(@"\r\n|\r|\n")]
+	private static partial Regex LineBreakRegex();
+
+	public static string ToNewLine(this LineEndings lineEndings) => lineEndings switch
+	{
+		LineEndings.Crlf => "\r\n",
+		LineEndings.Lf => "\n",
+		_ => throw new ArgumentOutOfRangeException(nameof(lineEndings), lineEndings, "Unknown line ending"),
+	};
+
+	/// <summary>
+	/// Replaces every line break in <paramref name="input"/> with the configured line ending,
+	/// so generated files are identical regardless of the OS TypeContractor runs on.
+	/// </summary>
+	public static string NormalizeLineEndings(string input, LineEndings lineEndings) =>
+		LineBreakRegex().Replace(input, lineEndings.ToNewLine());
+}

TypeContractor/LineEndings.cs

@@ -0,0 +1,14 @@
+namespace TypeContractor;
+
+public enum LineEndings
+{
+	/// <summary>
+	/// Windows line endings (\r\n)
+	/// </summary>
+	Crlf,
+
+	/// <summary>
+	/// Unix line endings (\n)
+	/// </summary>
+	Lf,
+}

TypeContractor/TypeContractorConfiguration.cs

@@ -18,6 +18,7 @@ public class TypeContractorConfiguration
 	private List<ApiClient> _apiClients = [];
 	private string? _apiClientTemplate;
 	private Casing? _casing;
+	private LineEndings? _lineEndings;
 
 	public IReadOnlyDictionary<string, string> TypeMaps => _map;
 	public IReadOnlyList<string> Suffixes => _suffixes.AsReadOnly();
@@ -31,6 +32,7 @@ public class TypeContractorConfiguration
 	public IReadOnlyList<ApiClient> ApiClients => _apiClients.AsReadOnly();
 	public string ApiClientTemplate => _apiClientTemplate ?? "aurelia";
 	public Casing Casing => _casing ?? Casing.Kebab;
+	public LineEndings LineEndings => _lineEndings ?? LineEndings.Crlf;
 
 	/// <summary>
 	/// Set up a default configuration using <see cref="AddDefaultSuffixes"/> and <see cref="AddDefaultTypeMaps"/>
@@ -292,6 +294,16 @@ public TypeContractorConfiguration SetCasing(Casing casing)
 		return this;
 	}
 
+	/// <summary>
+	/// Set the line endings to use in generated files. Default is <c>crlf</c>.
+	/// </summary>
+	/// <returns>The configuration object for continued chaining</returns>
+	public TypeContractorConfiguration SetLineEndings(LineEndings lineEndings)
+	{
+		_lineEndings = lineEndings;
+		return this;
+	}
+
 	/// <summary>
 	/// Enable generation of API clients for relevant endpoints.
 	/// 

TypeContractor/TypeScript/ApiClientWriter.cs

@@ -9,7 +9,7 @@
 
 namespace TypeContractor.TypeScript;
 
-public partial class ApiClientWriter(string outputPath, string? relativeRoot)
+public partial class ApiClientWriter(string outputPath, string? relativeRoot, LineEndings lineEndings = LineEndings.Crlf)
 {
 	private static readonly Encoding _utf8WithoutBom = new UTF8Encoding(encoderShouldEmitUTF8Identifier: false);
 	private static readonly Dictionary<EndpointMethod, string> _httpMethods = new()
@@ -165,7 +165,7 @@ public string Write(ApiClient apiClient, IEnumerable<OutputType> allTypes, TypeS
 			Directory.CreateDirectory(directory);
 
 		// Write file
-		File.WriteAllText(filePath, result.Trim() + Environment.NewLine, _utf8WithoutBom);
+		File.WriteAllText(filePath, LineEndingHelpers.NormalizeLineEndings(result.Trim(), lineEndings) + lineEndings.ToNewLine(), _utf8WithoutBom);
 
 		// Return the path we wrote to
 		return filePath;

TypeContractor/TypeScript/TypeScriptWriter.cs

@@ -6,7 +6,7 @@
 namespace TypeContractor.TypeScript;
 
 #pragma warning disable CA1305 // Specify IFormatProvider
-public class TypeScriptWriter(string outputPath)
+public class TypeScriptWriter(string outputPath, LineEndings lineEndings = LineEndings.Crlf)
 {
 	private static readonly Encoding _utf8WithoutBom = new UTF8Encoding(encoderShouldEmitUTF8Identifier: false);
 	private readonly StringBuilder _builder = new();
@@ -31,7 +31,7 @@ public string Write(OutputType outputType, IEnumerable<OutputType> allTypes, boo
 			Directory.CreateDirectory(directory);
 
 		// Write file
-		File.WriteAllText(filePath, _builder.ToString().Trim() + Environment.NewLine, _utf8WithoutBom);
+		File.WriteAllText(filePath, LineEndingHelpers.NormalizeLineEndings(_builder.ToString().Trim(), lineEndings) + lineEndings.ToNewLine(), _utf8WithoutBom);
 
 		// Return the path we wrote to
 		return filePath;