Add regression tests for path casing normalization

PathUtilL0:
- Folder casing normalization (create MiXeDcAsE, query lowercase)
- Idempotency (calling twice returns same result)
- Input casing independence (upper and lower resolve to same canonical)

HostContextL0:
- Root directory returns cached value across calls
- Derived paths (Diag, Externals) share Root prefix casing

.devcontainer/devcontainer.json

@@ -4,7 +4,7 @@
   "features": {
     "ghcr.io/devcontainers/features/docker-in-docker:2": {},
     "ghcr.io/devcontainers/features/dotnet": {
-      "version": "8.0.421"
+      "version": "8.0.420"
     },
     "ghcr.io/devcontainers/features/node:1": {
       "version": "20"

docs/start/envlinux.md

@@ -25,11 +25,11 @@ The `installdependencies.sh` script should install all required dependencies on
 
 Debian based OS (Debian, Ubuntu, Linux Mint)
 
-- liblttng-ust1t64, liblttng-ust1 or liblttng-ust0
+- liblttng-ust1 or liblttng-ust0
 - libkrb5-3
 - zlib1g
 - libssl3t64, libssl3, libssl1.1, libssl1.0.2 or libssl1.0.0
-- libicu80, libicu79, ..., libicu66, libicu65, libicu63, libicu60, libicu57, libicu55, or libicu52
+- libicu76, libicu75, ..., libicu66, libicu65, libicu63, libicu60, libicu57, libicu55, or libicu52
 
 Fedora based OS (Fedora, Red Hat Enterprise Linux, CentOS, Oracle Linux 7)
 

images/Dockerfile

@@ -5,8 +5,8 @@ ARG TARGETOS
 ARG TARGETARCH
 ARG RUNNER_VERSION
 ARG RUNNER_CONTAINER_HOOKS_VERSION=0.7.0
-ARG DOCKER_VERSION=29.5.0
-ARG BUILDX_VERSION=0.34.0
+ARG DOCKER_VERSION=29.4.0
+ARG BUILDX_VERSION=0.33.0
 
 RUN apt update -y && apt install curl unzip -y
 

src/Misc/layoutbin/installdependencies.sh

@@ -94,7 +94,7 @@ then
             fi
         }
 
-        apt_get_with_fallbacks liblttng-ust1t64 liblttng-ust1 liblttng-ust0
+        apt_get_with_fallbacks liblttng-ust1 liblttng-ust0
         if [ $? -ne 0 ]
         then
             echo "'$apt_get' failed with exit code '$?'"
@@ -110,7 +110,7 @@ then
             exit 1
         fi
 
-        apt_get_with_fallbacks libicu80 libicu79 libicu78 libicu77 libicu76 libicu75 libicu74 libicu73 libicu72 libicu71 libicu70 libicu69 libicu68 libicu67 libicu66 libicu65 libicu63 libicu60 libicu57 libicu55 libicu52
+        apt_get_with_fallbacks libicu76 libicu75 libicu74 libicu73 libicu72 libicu71 libicu70 libicu69 libicu68 libicu67 libicu66 libicu65 libicu63 libicu60 libicu57 libicu55 libicu52
         if [ $? -ne 0 ]
         then
             echo "'$apt_get' failed with exit code '$?'"

src/Runner.Common/Constants.cs

@@ -179,7 +179,6 @@ namespace GitHub.Runner.Common
                 public static readonly string EmitCompositeMarkers = "actions_runner_emit_composite_markers";
                 public static readonly string BatchActionResolution = "actions_batch_action_resolution";
                 public static readonly string UseBearerTokenForCodeload = "actions_use_bearer_token_for_codeload";
-                public static readonly string OverrideDebuggerWelcomeMessage = "actions_runner_override_debugger_welcome_message";
             }
 
             // Node version migration related constants

src/Runner.Common/HostContext.cs

@@ -64,6 +64,7 @@ namespace GitHub.Runner.Common
         private readonly List<ProductInfoHeaderValue> _userAgents = new() { new ProductInfoHeaderValue($"GitHubActionsRunner-{BuildConstants.RunnerPackage.PackageName}", BuildConstants.RunnerPackage.Version) };
         private CancellationTokenSource _runnerShutdownTokenSource = new();
         private object _perfLock = new();
+        private string _canonicalRootDirectory;
         private Tracing _trace;
         private Tracing _actionsHttpTrace;
         private Tracing _netcoreHttpTrace;
@@ -391,7 +392,12 @@ namespace GitHub.Runner.Common
                     break;
 
                 case WellKnownDirectory.Root:
-                    path = new DirectoryInfo(GetDirectory(WellKnownDirectory.Bin)).Parent.FullName;
+                    if (_canonicalRootDirectory == null)
+                    {
+                        _canonicalRootDirectory = PathUtil.GetCanonicalPath(
+                            new DirectoryInfo(GetDirectory(WellKnownDirectory.Bin)).Parent.FullName);
+                    }
+                    path = _canonicalRootDirectory;
                     break;
 
                 case WellKnownDirectory.Temp:

src/Runner.Sdk/Util/PathUtil.cs

@@ -1,4 +1,7 @@
 using System.IO;
+using System.Runtime.InteropServices;
+using System.Text;
+using Microsoft.Win32.SafeHandles;
 
 namespace GitHub.Runner.Sdk
 {
@@ -6,8 +9,98 @@ namespace GitHub.Runner.Sdk
     {
 #if OS_WINDOWS
         public static readonly string PathVariable = "Path";
+
+        [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
+        private static extern SafeFileHandle CreateFile(
+            string lpFileName,
+            uint dwDesiredAccess,
+            uint dwShareMode,
+            System.IntPtr lpSecurityAttributes,
+            uint dwCreationDisposition,
+            uint dwFlagsAndAttributes,
+            System.IntPtr hTemplateFile);
+
+        [DllImport("kernel32.dll", SetLastError = true, CharSet = CharSet.Unicode)]
+        private static extern uint GetFinalPathNameByHandle(
+            SafeFileHandle hFile,
+            [Out] StringBuilder lpszFilePath,
+            uint cchFilePath,
+            uint dwFlags);
+
+        private const uint FILE_READ_ATTRIBUTES = 0x80;
+        private const uint FILE_SHARE_READ = 0x1;
+        private const uint FILE_SHARE_WRITE = 0x2;
+        private const uint FILE_SHARE_DELETE = 0x4;
+        private const uint OPEN_EXISTING = 3;
+        private const uint FILE_FLAG_BACKUP_SEMANTICS = 0x02000000;
+        private const uint VOLUME_NAME_DOS = 0x0;
+
+        /// <summary>
+        /// Returns the NTFS canonical path for a directory, resolving drive letter
+        /// and folder name casing to match what is stored on disk.
+        /// On non-Windows platforms, returns the path unchanged.
+        /// </summary>
+        public static string GetCanonicalPath(string path)
+        {
+            if (string.IsNullOrEmpty(path) || !Directory.Exists(path))
+            {
+                return path;
+            }
+
+            using var handle = CreateFile(
+                path,
+                FILE_READ_ATTRIBUTES,
+                FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
+                System.IntPtr.Zero,
+                OPEN_EXISTING,
+                FILE_FLAG_BACKUP_SEMANTICS,
+                System.IntPtr.Zero);
+
+            if (handle.IsInvalid)
+            {
+                return path;
+            }
+
+            var buffer = new StringBuilder(1024);
+            var result = GetFinalPathNameByHandle(handle, buffer, (uint)buffer.Capacity, VOLUME_NAME_DOS);
+            if (result == 0)
+            {
+                return path;
+            }
+
+            // Retry with a larger buffer if the path was longer than expected
+            if (result >= buffer.Capacity)
+            {
+                buffer = new StringBuilder((int)result + 1);
+                result = GetFinalPathNameByHandle(handle, buffer, (uint)buffer.Capacity, VOLUME_NAME_DOS);
+                if (result == 0 || result >= buffer.Capacity)
+                {
+                    return path;
+                }
+            }
+
+            var canonicalPath = buffer.ToString();
+
+            // Strip the \\?\UNC\ prefix and convert to standard UNC path
+            if (canonicalPath.StartsWith(@"\\?\UNC\", System.StringComparison.Ordinal))
+            {
+                canonicalPath = @"\\" + canonicalPath.Substring(8);
+            }
+            // Strip the \\?\ prefix for local paths
+            else if (canonicalPath.StartsWith(@"\\?\", System.StringComparison.Ordinal))
+            {
+                canonicalPath = canonicalPath.Substring(4);
+            }
+
+            return canonicalPath;
+        }
 #else
         public static readonly string PathVariable = "PATH";
+
+        public static string GetCanonicalPath(string path)
+        {
+            return path;
+        }
 #endif
 
         public static string PrependPath(string path, string currentPath)

src/Runner.Worker/Dap/DapDebugger.cs

@@ -63,7 +63,6 @@ namespace GitHub.Runner.Worker.Dap
         private volatile DapSessionState _state = DapSessionState.NotStarted;
         private CancellationTokenRegistration? _cancellationRegistration;
         private bool _isFirstStep = true;
-        private bool _welcomeMessageSent;
 
         // Dev Tunnel relay host for remote debugging
         private TunnelRelayTunnelHost _tunnelRelayHost;
@@ -491,11 +490,6 @@ namespace GitHub.Runner.Worker.Dap
                     });
                     Trace.Info("Sent initialized event");
                 }
-
-                if (request.Command == "configurationDone")
-                {
-                    SendWelcomeMessage();
-                }
             }
             catch (Exception ex)
             {
@@ -514,7 +508,6 @@ namespace GitHub.Runner.Worker.Dap
         internal void HandleClientConnected()
         {
             _isClientConnected = true;
-            _welcomeMessageSent = false;
             Trace.Info("Client connected to debug session");
 
             // If we're paused, re-send the stopped event so the new client
@@ -825,34 +818,6 @@ namespace GitHub.Runner.Worker.Dap
             });
         }
 
-        internal void SendWelcomeMessage()
-        {
-            if (_welcomeMessageSent)
-            {
-                return;
-            }
-            _welcomeMessageSent = true;
-
-            var debuggerConfig = _jobContext?.Global?.Debugger;
-            if (debuggerConfig?.OverrideWelcomeMessage == true)
-            {
-                if (!string.IsNullOrEmpty(debuggerConfig.WelcomeMessage))
-                {
-                    SendOutput("console", debuggerConfig.WelcomeMessage);
-                    Trace.Info("Sent custom welcome message");
-                }
-                else
-                {
-                    Trace.Info("Welcome message suppressed by override");
-                }
-            }
-            else
-            {
-                SendOutput("console", DapReplParser.GetGeneralHelp());
-                Trace.Info("Sent default welcome message");
-            }
-        }
-
         internal async Task OnStepStartingAsync(IStep step, bool isFirstStep)
         {
             bool pauseOnNextStep;
@@ -895,9 +860,6 @@ namespace GitHub.Runner.Worker.Dap
             // Send stopped event to debugger (only if client is connected)
             SendStoppedEvent(reason, description);
 
-            // Emit a banner so the user knows where REPL commands will execute
-            SendExecutionContextBanner();
-
             // Wait for debugger command
             await WaitForCommandAsync(cancellationToken);
         }
@@ -1233,12 +1195,7 @@ namespace GitHub.Runner.Worker.Dap
 
                 case RunCommand run:
                     var context = GetExecutionContextForFrame(frameId);
-                    bool isActionStep;
-                    lock (_stateLock)
-                    {
-                        isActionStep = _currentStep is IActionRunner;
-                    }
-                    return await _replExecutor.ExecuteRunCommandAsync(run, context, isActionStep, cancellationToken);
+                    return await _replExecutor.ExecuteRunCommandAsync(run, context, cancellationToken);
 
                 default:
                     return new EvaluateResponseBody
@@ -1450,40 +1407,6 @@ namespace GitHub.Runner.Worker.Dap
             });
         }
 
-        /// <summary>
-        /// Emits a console output banner telling the user whether REPL
-        /// commands will execute on the host or inside the job container.
-        /// </summary>
-        private void SendExecutionContextBanner()
-        {
-            if (!_isClientConnected)
-            {
-                return;
-            }
-
-            bool isActionStep = _currentStep is IActionRunner;
-            var container = _jobContext?.Global?.Container;
-
-            string target;
-            if (isActionStep && container != null &&
-                (!string.IsNullOrEmpty(container.ContainerId) ||
-                 FeatureManager.IsContainerHooksEnabled(_jobContext?.Global?.Variables)))
-            {
-                var image = container.ContainerImage ?? "container";
-                var shortId = !string.IsNullOrEmpty(container.ContainerId) && container.ContainerId.Length >= 12
-                    ? container.ContainerId.Substring(0, 12)
-                    : container.ContainerId ?? "";
-                var idSuffix = !string.IsNullOrEmpty(shortId) ? $" ({shortId})" : "";
-                target = $"job container: {image}{idSuffix}";
-            }
-            else
-            {
-                target = "runner host";
-            }
-
-            SendOutput("console", $"\nCommands will run on {target}\n");
-        }
-
         private string MaskUserVisibleText(string value)
         {
             if (string.IsNullOrEmpty(value))

src/Runner.Worker/Dap/DapReplExecutor.cs

@@ -9,7 +9,6 @@ using GitHub.DistributedTask.Pipelines.ContextData;
 using GitHub.Runner.Common;
 using GitHub.Runner.Common.Util;
 using GitHub.Runner.Sdk;
-using GitHub.Runner.Worker.Container;
 using GitHub.Runner.Worker.Handlers;
 
 namespace GitHub.Runner.Worker.Dap
@@ -44,7 +43,6 @@ namespace GitHub.Runner.Worker.Dap
         public async Task<EvaluateResponseBody> ExecuteRunCommandAsync(
             RunCommand command,
             IExecutionContext context,
-            bool isActionStep,
             CancellationToken cancellationToken)
         {
             if (context == null)
@@ -54,7 +52,7 @@ namespace GitHub.Runner.Worker.Dap
 
             try
             {
-                return await ExecuteScriptAsync(command, context, isActionStep, cancellationToken);
+                return await ExecuteScriptAsync(command, context, cancellationToken);
             }
             catch (Exception ex)
             {
@@ -67,17 +65,9 @@ namespace GitHub.Runner.Worker.Dap
         private async Task<EvaluateResponseBody> ExecuteScriptAsync(
             RunCommand command,
             IExecutionContext context,
-            bool isActionStep,
             CancellationToken cancellationToken)
         {
-            // 1. Resolve step host — container or host, same as ActionRunner.
-            //    Only action steps (user-defined run:/uses:) execute inside the
-            //    container.  Infrastructure steps (Set up job, Initialize
-            //    containers, Complete job, etc.) always run on the host.
-            var stepHost = CreateStepHost(context, isActionStep);
-            var isContainerStepHost = stepHost is IContainerStepHost;
-
-            // 2. Resolve shell — same logic as ScriptHandler
+            // 1. Resolve shell — same logic as ScriptHandler
             string shellCommand;
             string argFormat;
 
@@ -97,9 +87,9 @@ namespace GitHub.Runner.Worker.Dap
                 argFormat = ScriptHandlerHelpers.GetScriptArgumentsFormat(shellCommand);
             }
 
-            _trace.Info($"Resolved REPL shell (container={isContainerStepHost})");
+            _trace.Info("Resolved REPL shell");
 
-            // 3. Expand ${{ }} expressions in the script body, just like
+            // 2. Expand ${{ }} expressions in the script body, just like
             //    ActionRunner evaluates step inputs before ScriptHandler sees them
             var contents = ExpandExpressions(command.Script, context);
             contents = ScriptHandlerHelpers.FixUpScriptContents(shellCommand, contents);
@@ -121,47 +111,25 @@ namespace GitHub.Runner.Worker.Dap
 
             try
             {
-                // 4. Resolve script path — translate for container if needed
-                var resolvedPath = stepHost.ResolvePathForStepHost(context, scriptFilePath).Replace("\"", "\\\"");
+                // 3. Format arguments with script path
+                var resolvedPath = scriptFilePath.Replace("\"", "\\\"");
                 if (string.IsNullOrEmpty(argFormat) || !argFormat.Contains("{0}"))
                 {
                     return ErrorResult($"Invalid shell option '{shellCommand}'. Shell must be a valid built-in (bash, sh, cmd, powershell, pwsh) or a format string containing '{{0}}'");
                 }
                 var arguments = string.Format(argFormat, resolvedPath);
 
-                // 5. Resolve shell command path — for containers, use the shell
-                //    name directly (it will be resolved inside the container);
-                //    for host execution, resolve the full path on the host.
+                // 4. Resolve shell command path
                 string prependPath = string.Join(
                     Path.PathSeparator.ToString(),
                     Enumerable.Reverse(context.Global.PrependPath));
-                var fileName = isContainerStepHost
-                    ? shellCommand
-                    : WhichUtil.Which(shellCommand, false, _trace, prependPath) ?? shellCommand;
+                var commandPath = WhichUtil.Which(shellCommand, false, _trace, prependPath)
+                    ?? shellCommand;
 
-                // 6. Build environment — merge from execution context like a real step
+                // 5. Build environment — merge from execution context like a real step
                 var environment = BuildEnvironment(context, command.Env);
 
-                // 7. Handle PrependPath — mirrors Handler.AddPrependPathToEnvironment
-                if (context.Global.PrependPath.Count > 0)
-                {
-                    if (stepHost is IContainerStepHost containerHost)
-                    {
-                        containerHost.PrependPath = prependPath;
-                    }
-                    else
-                    {
-                        string taskEnvPATH;
-                        environment.TryGetValue(Constants.PathVariable, out taskEnvPATH);
-                        string originalPath = context.Global.Variables?.Get(Constants.PathVariable) ?? // Prefer a job variable.
-                            taskEnvPATH ?? // Then a task-environment variable.
-                            System.Environment.GetEnvironmentVariable(Constants.PathVariable) ?? // Then an environment variable.
-                            string.Empty;
-                        environment[Constants.PathVariable] = PathUtil.PrependPath(prependPath, originalPath);
-                    }
-                }
-
-                // 8. Resolve working directory — translate for container
+                // 6. Resolve working directory
                 var workingDirectory = command.WorkingDirectory;
                 if (string.IsNullOrEmpty(workingDirectory))
                 {
@@ -173,60 +141,48 @@ namespace GitHub.Runner.Worker.Dap
                         : null;
                     workingDirectory = workspace ?? _hostContext.GetDirectory(WellKnownDirectory.Work);
                 }
-                workingDirectory = stepHost.ResolvePathForStepHost(context, workingDirectory);
 
                 _trace.Info("Executing REPL command");
 
                 // Stream execution info to debugger
                 SendOutput("console", $"$ {shellCommand} {command.Script.Substring(0, Math.Min(command.Script.Length, 80))}{(command.Script.Length > 80 ? "..." : "")}\n");
 
-                // NOTE: When container hooks are enabled, ContainerStepHost routes
-                // execution through IContainerHookManager which does not raise
-                // OutputDataReceived/ErrorDataReceived events. Output will not be
-                // streamed to the debug console in that mode.
-                if (isContainerStepHost && FeatureManager.IsContainerHooksEnabled(context.Global?.Variables))
+                // 7. Execute via IProcessInvoker (same as DefaultStepHost)
+                int exitCode;
+                using (var processInvoker = _hostContext.CreateService<IProcessInvoker>())
                 {
-                    const string hookWarning = "Container hooks are enabled. REPL output will not be streamed to the debug console for this command.";
-                    _trace.Warning(hookWarning);
-                    SendOutput("stderr", hookWarning + "\n");
+                    processInvoker.OutputDataReceived += (sender, args) =>
+                    {
+                        if (!string.IsNullOrEmpty(args.Data))
+                        {
+                            var masked = _hostContext.SecretMasker.MaskSecrets(args.Data);
+                            SendOutput("stdout", masked + "\n");
+                        }
+                    };
+
+                    processInvoker.ErrorDataReceived += (sender, args) =>
+                    {
+                        if (!string.IsNullOrEmpty(args.Data))
+                        {
+                            var masked = _hostContext.SecretMasker.MaskSecrets(args.Data);
+                            SendOutput("stderr", masked + "\n");
+                        }
+                    };
+
+                    exitCode = await processInvoker.ExecuteAsync(
+                        workingDirectory: workingDirectory,
+                        fileName: commandPath,
+                        arguments: arguments,
+                        environment: environment,
+                        requireExitCodeZero: false,
+                        outputEncoding: null,
+                        killProcessOnCancel: true,
+                        cancellationToken: cancellationToken);
                 }
 
-                // 9. Execute via IStepHost — handles docker exec for containers,
-                //    direct process execution for host, and container hooks
-                stepHost.OutputDataReceived += (sender, args) =>
-                {
-                    if (!string.IsNullOrEmpty(args.Data))
-                    {
-                        var masked = _hostContext.SecretMasker.MaskSecrets(args.Data);
-                        SendOutput("stdout", masked + "\n");
-                    }
-                };
-
-                stepHost.ErrorDataReceived += (sender, args) =>
-                {
-                    if (!string.IsNullOrEmpty(args.Data))
-                    {
-                        var masked = _hostContext.SecretMasker.MaskSecrets(args.Data);
-                        SendOutput("stderr", masked + "\n");
-                    }
-                };
-
-                int exitCode = await stepHost.ExecuteAsync(
-                    context: context,
-                    workingDirectory: workingDirectory,
-                    fileName: fileName,
-                    arguments: arguments,
-                    environment: environment,
-                    requireExitCodeZero: false,
-                    outputEncoding: null,
-                    killProcessOnCancel: true,
-                    inheritConsoleHandler: false,
-                    standardInInput: null,
-                    cancellationToken: cancellationToken);
-
                 _trace.Info($"REPL command exited with code {exitCode}");
 
-                // 10. Return only the exit code summary (output was already streamed)
+                // 8. Return only the exit code summary (output was already streamed)
                 return new EvaluateResponseBody
                 {
                     Result = exitCode == 0 ? $"(exit code: {exitCode})" : $"Process completed with exit code {exitCode}.",
@@ -242,43 +198,6 @@ namespace GitHub.Runner.Worker.Dap
             }
         }
 
-        /// <summary>
-        /// Creates the appropriate <see cref="IStepHost"/> for the current
-        /// execution context, mirroring how <see cref="ActionRunner"/> decides
-        /// between host and container execution.
-        ///
-        /// Only action steps (user-defined run:/uses: steps) run inside the
-        /// job container.  Infrastructure steps like "Set up job", "Initialize
-        /// containers", "Stop containers", and "Complete job" always execute
-        /// on the host regardless of whether a container is configured.
-        /// </summary>
-        internal IStepHost CreateStepHost(IExecutionContext context, bool isActionStep)
-        {
-            if (!isActionStep)
-            {
-                _trace.Info("Creating DefaultStepHost for REPL execution (infrastructure step)");
-                return _hostContext.CreateService<IDefaultStepHost>();
-            }
-
-            var container = context?.Global?.Container;
-            if (container != null)
-            {
-                // Container hooks don't always set ContainerId, but the container
-                // step host handles that internally
-                var hooksEnabled = FeatureManager.IsContainerHooksEnabled(context.Global?.Variables);
-                if (hooksEnabled || !string.IsNullOrEmpty(container.ContainerId))
-                {
-                    _trace.Info("Creating ContainerStepHost for REPL execution");
-                    var containerStepHost = _hostContext.CreateService<IContainerStepHost>();
-                    containerStepHost.Container = container;
-                    return containerStepHost;
-                }
-            }
-
-            _trace.Info("Creating DefaultStepHost for REPL execution");
-            return _hostContext.CreateService<IDefaultStepHost>();
-        }
-
         /// <summary>
         /// Expands <c>${{ }}</c> expressions in the input string using the
         /// runner's template evaluator — the same evaluation path that processes

src/Runner.Worker/Dap/DebuggerConfig.cs

@@ -1,4 +1,4 @@
-using GitHub.DistributedTask.Pipelines;
+using GitHub.DistributedTask.Pipelines;
 
 namespace GitHub.Runner.Worker.Dap
 {
@@ -8,12 +8,10 @@ namespace GitHub.Runner.Worker.Dap
     /// </summary>
     public sealed class DebuggerConfig
     {
-        public DebuggerConfig(bool enabled, DebuggerTunnelInfo tunnel, bool overrideWelcomeMessage = false, string welcomeMessage = null)
+        public DebuggerConfig(bool enabled, DebuggerTunnelInfo tunnel)
         {
             Enabled = enabled;
             Tunnel = tunnel;
-            OverrideWelcomeMessage = overrideWelcomeMessage;
-            WelcomeMessage = welcomeMessage;
         }
 
         /// <summary>Whether the debugger is enabled for this job.</summary>
@@ -25,19 +23,6 @@ namespace GitHub.Runner.Worker.Dap
         /// </summary>
         public DebuggerTunnelInfo Tunnel { get; }
 
-        /// <summary>
-        /// When true, the runner overrides the default welcome message with
-        /// <see cref="WelcomeMessage"/>. A null or empty <see cref="WelcomeMessage"/>
-        /// suppresses the message entirely. When false, the default help text is shown.
-        /// </summary>
-        public bool OverrideWelcomeMessage { get; }
-
-        /// <summary>
-        /// Optional welcome message content for the debugger console. Only used when
-        /// <see cref="OverrideWelcomeMessage"/> is true.
-        /// </summary>
-        public string WelcomeMessage { get; }
-
         /// <summary>Whether the tunnel configuration is complete and valid.</summary>
         public bool HasValidTunnel => Tunnel != null
             && !string.IsNullOrEmpty(Tunnel.TunnelId)

src/Runner.Worker/Dap/YamlScalarFormatter.cs

@@ -1,63 +0,0 @@
-using System;
-using System.Globalization;
-using System.IO;
-using GitHub.Runner.Sdk;
-using YamlDotNet.Core;
-using YamlDotNet.Core.Events;
-
-namespace GitHub.Runner.Worker.Dap
-{
-    /// <summary>
-    /// Formats a single string as a quote-safe YAML scalar by routing it
-    /// through YamlDotNet's <see cref="Emitter"/>. The returned text is
-    /// safe to splice into a hand-emitted YAML document fragment.
-    ///
-    /// Caller responsibility: this only handles the scalar value; it does
-    /// not emit a key, indent, or trailing newline.
-    /// </summary>
-    internal static class YamlScalarFormatter
-    {
-        /// <summary>
-        /// Return <paramref name="value"/> formatted as a YAML scalar:
-        /// plain, single-quoted, or double-quoted as the emitter chooses,
-        /// with no surrounding document markers or trailing newline.
-        /// </summary>
-        public static string Format(string value)
-        {
-            ArgUtil.NotNull(value, nameof(value));
-
-            using var sw = new StringWriter(CultureInfo.InvariantCulture);
-            // Force LF line breaks; YamlDotNet's Emitter calls WriteLine,
-            // which would otherwise produce CRLF on Windows and break
-            // both our document-end stripping below and downstream
-            // consumers that assume a single line-break convention.
-            sw.NewLine = "\n";
-            var emitter = new Emitter(sw);
-            emitter.Emit(new StreamStart());
-            emitter.Emit(new DocumentStart(null, null, true));
-            emitter.Emit(new Scalar(null, null, value, ScalarStyle.Any, true, true));
-            emitter.Emit(new DocumentEnd(true));
-            emitter.Emit(new StreamEnd());
-
-            string raw = sw.ToString();
-            // Strip YAML document markers. Emitter elides these for most
-            // scalars but emits "--- " (with space) for some edge cases
-            // (e.g. empty strings). Defensively handle "---\n" too.
-            if (raw.StartsWith("--- ", StringComparison.Ordinal))
-            {
-                raw = raw.Substring(4);
-            }
-            else if (raw.StartsWith("---\n", StringComparison.Ordinal))
-            {
-                raw = raw.Substring(4);
-            }
-            raw = raw.TrimEnd('\n');
-            const string DocEndMarker = "\n...";
-            if (raw.EndsWith(DocEndMarker, StringComparison.Ordinal))
-            {
-                raw = raw.Substring(0, raw.Length - DocEndMarker.Length);
-            }
-            return raw;
-        }
-    }
-}

src/Runner.Worker/ExecutionContext.cs

@@ -970,8 +970,7 @@ namespace GitHub.Runner.Worker
             Global.WriteDebug = Global.Variables.Step_Debug ?? false;
 
             // Debugger enabled flag (from acquire response).
-            var overrideDebuggerWelcomeMessage = Global.Variables.GetBoolean(Constants.Runner.Features.OverrideDebuggerWelcomeMessage) ?? false;
-            Global.Debugger = new Dap.DebuggerConfig(message.EnableDebugger, message.DebuggerTunnel, overrideDebuggerWelcomeMessage, message.DebuggerWelcomeMessage);
+            Global.Debugger = new Dap.DebuggerConfig(message.EnableDebugger, message.DebuggerTunnel);
 
             // Hook up JobServerQueueThrottling event, we will log warning on server tarpit.
             _jobServerQueue.JobServerQueueThrottling += JobServerQueueThrottling_EventReceived;

src/Sdk/DTPipelines/Pipelines/AgentJobRequestMessage.cs

@@ -267,21 +267,6 @@ namespace GitHub.DistributedTask.Pipelines
             set;
         }
 
-        /// <summary>
-        /// Optional welcome message shown in the debugger console when a client connects.
-        /// Only used when the <c>actions_runner_override_debugger_welcome_message</c>
-        /// feature flag is set to <c>true</c> in the job variables. With the flag set,
-        /// a non-empty value is shown as-is and a null or empty value suppresses the
-        /// default welcome message. When the flag is not set, the runner shows its
-        /// built-in help text and this field is ignored.
-        /// </summary>
-        [DataMember(EmitDefaultValue = false)]
-        public string DebuggerWelcomeMessage
-        {
-            get;
-            set;
-        }
-
         /// <summary>
         /// Gets the workflow-level action dependencies (lockfile entries)
         /// </summary>

src/Test/L0/HostContextL0.cs

@@ -299,6 +299,52 @@ namespace GitHub.Runner.Common.Tests
             }
         }
 
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Common")]
+        public void GetDirectoryRootReturnsCachedValue()
+        {
+            try
+            {
+                Setup();
+
+                // Call GetDirectory(Root) twice — should return the same reference
+                var root1 = _hc.GetDirectory(WellKnownDirectory.Root);
+                var root2 = _hc.GetDirectory(WellKnownDirectory.Root);
+
+                Assert.NotNull(root1);
+                Assert.Equal(root1, root2);
+                Assert.True(Directory.Exists(root1));
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Common")]
+        public void GetDirectoryDerivedPathsUseRootCasing()
+        {
+            try
+            {
+                Setup();
+
+                var root = _hc.GetDirectory(WellKnownDirectory.Root);
+                var diag = _hc.GetDirectory(WellKnownDirectory.Diag);
+                var externals = _hc.GetDirectory(WellKnownDirectory.Externals);
+
+                // Diag and Externals should start with the same Root prefix
+                Assert.StartsWith(root, diag);
+                Assert.StartsWith(root, externals);
+            }
+            finally
+            {
+                Teardown();
+            }
+        }
+
         private void Setup([CallerMemberName] string testName = "")
         {
             _tokenSource = new CancellationTokenSource();

src/Test/L0/Sdk/RSWebApi/AgentJobRequestMessageL0.cs

@@ -1,4 +1,4 @@
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.IO;
 using System.Runtime.Serialization.Json;
 using System.Text;
@@ -17,13 +17,13 @@ public sealed class AgentJobRequestMessageL0
         // Arrange
         var serializer = new DataContractJsonSerializer(typeof(AgentJobRequestMessage));
         string jsonWithEnabledDebugger = DoubleQuotify("{'EnableDebugger': true}");
-
+        
         // Act
         using var stream = new MemoryStream();
         stream.Write(Encoding.UTF8.GetBytes(jsonWithEnabledDebugger));
         stream.Position = 0;
         var recoveredMessage = serializer.ReadObject(stream) as AgentJobRequestMessage;
-
+        
         // Assert
         Assert.NotNull(recoveredMessage);
         Assert.True(recoveredMessage.EnableDebugger, "EnableDebugger should be true when JSON contains 'EnableDebugger': true");
@@ -37,13 +37,13 @@ public sealed class AgentJobRequestMessageL0
         // Arrange
         var serializer = new DataContractJsonSerializer(typeof(AgentJobRequestMessage));
         string jsonWithoutDebugger = DoubleQuotify("{'messageType': 'PipelineAgentJobRequest'}");
-
+        
         // Act
         using var stream = new MemoryStream();
         stream.Write(Encoding.UTF8.GetBytes(jsonWithoutDebugger));
         stream.Position = 0;
         var recoveredMessage = serializer.ReadObject(stream) as AgentJobRequestMessage;
-
+        
         // Assert
         Assert.NotNull(recoveredMessage);
         Assert.False(recoveredMessage.EnableDebugger, "EnableDebugger should default to false when JSON field is absent");
@@ -57,13 +57,13 @@ public sealed class AgentJobRequestMessageL0
         // Arrange
         var serializer = new DataContractJsonSerializer(typeof(AgentJobRequestMessage));
         string jsonWithDisabledDebugger = DoubleQuotify("{'EnableDebugger': false}");
-
+        
         // Act
         using var stream = new MemoryStream();
         stream.Write(Encoding.UTF8.GetBytes(jsonWithDisabledDebugger));
         stream.Position = 0;
         var recoveredMessage = serializer.ReadObject(stream) as AgentJobRequestMessage;
-
+        
         // Assert
         Assert.NotNull(recoveredMessage);
         Assert.False(recoveredMessage.EnableDebugger, "EnableDebugger should be false when JSON contains 'EnableDebugger': false");
@@ -161,26 +161,6 @@ public sealed class AgentJobRequestMessageL0
         Assert.Empty(recoveredMessage.ActionsDependencies);
     }
 
-    [Fact]
-    [Trait("Level", "L0")]
-    [Trait("Category", "Common")]
-    public void VerifyDebuggerWelcomeMessageRoundTrips()
-    {
-        // Arrange
-        var serializer = new DataContractJsonSerializer(typeof(AgentJobRequestMessage));
-        string json = DoubleQuotify("{'DebuggerWelcomeMessage': 'Welcome to debugging!'}");
-
-        // Act
-        using var stream = new MemoryStream();
-        stream.Write(Encoding.UTF8.GetBytes(json));
-        stream.Position = 0;
-        var recoveredMessage = serializer.ReadObject(stream) as AgentJobRequestMessage;
-
-        // Assert
-        Assert.NotNull(recoveredMessage);
-        Assert.Equal("Welcome to debugging!", recoveredMessage.DebuggerWelcomeMessage);
-    }
-
     private static string DoubleQuotify(string text)
     {
         return text.Replace('\'', '"');

src/Test/L0/Util/PathUtilL0.cs

@@ -0,0 +1,151 @@
+using GitHub.Runner.Sdk;
+using System.IO;
+using System.Runtime.InteropServices;
+using Xunit;
+
+namespace GitHub.Runner.Common.Tests.Util
+{
+    public sealed class PathUtilL0
+    {
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Common")]
+        public void GetCanonicalPath_ReturnsPath_WhenDirectoryDoesNotExist()
+        {
+            var fakePath = Path.Combine(Path.GetTempPath(), "nonexistent_" + Path.GetRandomFileName());
+            var result = PathUtil.GetCanonicalPath(fakePath);
+            Assert.Equal(fakePath, result);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Common")]
+        public void GetCanonicalPath_ReturnsPath_WhenNull()
+        {
+            Assert.Null(PathUtil.GetCanonicalPath(null));
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Common")]
+        public void GetCanonicalPath_ReturnsEmpty_WhenEmpty()
+        {
+            Assert.Equal(string.Empty, PathUtil.GetCanonicalPath(string.Empty));
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Common")]
+        public void GetCanonicalPath_ReturnsValidPath_ForExistingDirectory()
+        {
+            var tempDir = Path.Combine(Path.GetTempPath(), "pathutil_test_" + Path.GetRandomFileName());
+            try
+            {
+                Directory.CreateDirectory(tempDir);
+                var result = PathUtil.GetCanonicalPath(tempDir);
+                Assert.NotNull(result);
+                Assert.True(Directory.Exists(result));
+            }
+            finally
+            {
+                if (Directory.Exists(tempDir))
+                {
+                    Directory.Delete(tempDir);
+                }
+            }
+        }
+
+#if OS_WINDOWS
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Common")]
+        public void GetCanonicalPath_NormalizesDriveLetter_OnWindows()
+        {
+            var tempDir = Path.GetTempPath().TrimEnd(Path.DirectorySeparatorChar);
+
+            // Skip if temp is a UNC path (no drive letter to normalize)
+            if (tempDir.StartsWith(@"\\"))
+            {
+                return;
+            }
+
+            // Force lowercase drive letter
+            var lowerCased = char.ToLower(tempDir[0]) + tempDir.Substring(1);
+
+            var result = PathUtil.GetCanonicalPath(lowerCased);
+
+            // The canonical path should have an uppercase drive letter
+            Assert.True(char.IsUpper(result[0]),
+                $"Expected uppercase drive letter but got: {result}");
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Common")]
+        public void GetCanonicalPath_NormalizesFolderCasing_OnWindows()
+        {
+            // Create a directory with known casing, then query with wrong casing
+            var basePath = Path.GetTempPath();
+            if (basePath.StartsWith(@"\\"))
+            {
+                return; // Skip UNC
+            }
+
+            var realName = "PathUtilTest_MiXeDcAsE_" + Path.GetRandomFileName();
+            var realDir = Path.Combine(basePath, realName);
+            try
+            {
+                Directory.CreateDirectory(realDir);
+
+                // Query with all-lowercase version
+                var wrongCased = Path.Combine(basePath, realName.ToLowerInvariant());
+
+                var result = PathUtil.GetCanonicalPath(wrongCased);
+
+                // The canonical result should contain the original mixed-case name
+                Assert.Contains(realName, result);
+            }
+            finally
+            {
+                if (Directory.Exists(realDir))
+                {
+                    Directory.Delete(realDir);
+                }
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Common")]
+        public void GetCanonicalPath_IsIdempotent_OnWindows()
+        {
+            // Calling GetCanonicalPath twice should return the same result
+            var tempDir = Path.GetTempPath().TrimEnd(Path.DirectorySeparatorChar);
+            var first = PathUtil.GetCanonicalPath(tempDir);
+            var second = PathUtil.GetCanonicalPath(first);
+            Assert.Equal(first, second);
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Common")]
+        public void GetCanonicalPath_ReturnsSameResult_RegardlessOfInputCasing_OnWindows()
+        {
+            var tempDir = Path.GetTempPath().TrimEnd(Path.DirectorySeparatorChar);
+            if (tempDir.StartsWith(@"\\"))
+            {
+                return; // Skip UNC
+            }
+
+            var upper = tempDir.ToUpperInvariant();
+            var lower = tempDir.ToLowerInvariant();
+
+            var resultUpper = PathUtil.GetCanonicalPath(upper);
+            var resultLower = PathUtil.GetCanonicalPath(lower);
+
+            // Both should resolve to the same canonical path
+            Assert.Equal(resultUpper, resultLower);
+        }
+#endif
+    }
+}

src/Test/L0/Worker/DapDebuggerL0.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.IO;
 using System.Net;
 using System.Net.Sockets;
@@ -236,7 +236,7 @@ namespace GitHub.Runner.Common.Tests.Worker
             }
         }
 
-        private static Mock<IExecutionContext> CreateJobContextWithTunnel(CancellationToken cancellationToken, ushort port, string jobName = null, bool overrideWelcomeMessage = false, string welcomeMessage = null)
+        private static Mock<IExecutionContext> CreateJobContextWithTunnel(CancellationToken cancellationToken, ushort port, string jobName = null)
         {
             var tunnel = new GitHub.DistributedTask.Pipelines.DebuggerTunnelInfo
             {
@@ -245,7 +245,7 @@ namespace GitHub.Runner.Common.Tests.Worker
                 HostToken = "test-token",
                 Port = port
             };
-            var debuggerConfig = new DebuggerConfig(true, tunnel, overrideWelcomeMessage, welcomeMessage);
+            var debuggerConfig = new DebuggerConfig(true, tunnel);
             var jobContext = new Mock<IExecutionContext>();
             jobContext.Setup(x => x.CancellationToken).Returns(cancellationToken);
             jobContext.Setup(x => x.Global).Returns(new GlobalContext { Debugger = debuggerConfig });
@@ -742,8 +742,6 @@ namespace GitHub.Runner.Common.Tests.Worker
 
                 // Read the configurationDone response
                 await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
-                // Read the welcome message output event
-                await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
                 await waitTask;
 
                 // Complete the job — OnJobCompletedAsync pauses when stepping,
@@ -851,8 +849,6 @@ namespace GitHub.Runner.Common.Tests.Worker
                     Command = "configurationDone"
                 });
 
-                await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
-                // Read the welcome message output event
                 await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
                 await waitTask;
 
@@ -871,224 +867,5 @@ namespace GitHub.Runner.Common.Tests.Worker
                 Assert.Equal(completedTask, finished);
             }
         }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task WelcomeMessageSendsDefaultHelpWhenOverrideDisabled()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
-                await _debugger.StartAsync(jobContext.Object);
-
-                using var client = await ConnectClientAsync(port);
-                var stream = client.GetStream();
-
-                await SendRequestAsync(stream, new Request
-                {
-                    Seq = 1,
-                    Type = "request",
-                    Command = "configurationDone"
-                });
-
-                // First message: configurationDone response
-                var configDoneResponse = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
-                Assert.Contains("\"command\":\"configurationDone\"", configDoneResponse);
-
-                // Second message: welcome output event with default help text
-                var welcomeMsg = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
-                Assert.Contains("\"event\":\"output\"", welcomeMsg);
-                Assert.Contains("\"category\":\"console\"", welcomeMsg);
-                Assert.Contains("Actions Debug Console", welcomeMsg);
-                Assert.Contains("help", welcomeMsg);
-
-                await _debugger.StopAsync();
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task WelcomeMessageShowsCustomMessageWhenOverrideEnabled()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port,
-                    overrideWelcomeMessage: true,
-                    welcomeMessage: "Welcome to debugging!");
-                await _debugger.StartAsync(jobContext.Object);
-
-                using var client = await ConnectClientAsync(port);
-                var stream = client.GetStream();
-
-                await SendRequestAsync(stream, new Request
-                {
-                    Seq = 1,
-                    Type = "request",
-                    Command = "configurationDone"
-                });
-
-                // First: configurationDone response
-                var configDoneResponse = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
-                Assert.Contains("\"command\":\"configurationDone\"", configDoneResponse);
-
-                // Second: custom welcome message
-                var welcomeMsg = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
-                Assert.Contains("\"event\":\"output\"", welcomeMsg);
-                Assert.Contains("Welcome to debugging!", welcomeMsg);
-
-                await _debugger.StopAsync();
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task WelcomeMessageSuppressedWhenOverrideEnabledWithEmptyMessage()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port,
-                    overrideWelcomeMessage: true,
-                    welcomeMessage: "");
-                await _debugger.StartAsync(jobContext.Object);
-
-                using var client = await ConnectClientAsync(port);
-                var stream = client.GetStream();
-
-                await SendRequestAsync(stream, new Request
-                {
-                    Seq = 1,
-                    Type = "request",
-                    Command = "configurationDone"
-                });
-
-                // Read configurationDone response
-                var configDoneResponse = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
-                Assert.Contains("\"command\":\"configurationDone\"", configDoneResponse);
-
-                // Send threads request — if welcome message was suppressed, this
-                // should be the next response (no output event in between)
-                await SendRequestAsync(stream, new Request
-                {
-                    Seq = 2,
-                    Type = "request",
-                    Command = "threads"
-                });
-
-                var threadsResponse = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
-                Assert.Contains("\"command\":\"threads\"", threadsResponse);
-
-                await _debugger.StopAsync();
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task WelcomeMessageSuppressedWhenOverrideEnabledWithNullMessage()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port,
-                    overrideWelcomeMessage: true,
-                    welcomeMessage: null);
-                await _debugger.StartAsync(jobContext.Object);
-
-                using var client = await ConnectClientAsync(port);
-                var stream = client.GetStream();
-
-                await SendRequestAsync(stream, new Request
-                {
-                    Seq = 1,
-                    Type = "request",
-                    Command = "configurationDone"
-                });
-
-                // Read configurationDone response
-                var configDoneResponse = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
-                Assert.Contains("\"command\":\"configurationDone\"", configDoneResponse);
-
-                // Send threads request — if welcome message was suppressed, this
-                // should be the next response (no output event in between)
-                await SendRequestAsync(stream, new Request
-                {
-                    Seq = 2,
-                    Type = "request",
-                    Command = "threads"
-                });
-
-                var threadsResponse = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
-                Assert.Contains("\"command\":\"threads\"", threadsResponse);
-
-                await _debugger.StopAsync();
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task WelcomeMessageSentOnlyOnce()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
-                await _debugger.StartAsync(jobContext.Object);
-
-                using var client = await ConnectClientAsync(port);
-                var stream = client.GetStream();
-
-                // First configurationDone
-                await SendRequestAsync(stream, new Request
-                {
-                    Seq = 1,
-                    Type = "request",
-                    Command = "configurationDone"
-                });
-
-                var configDoneResponse = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
-                Assert.Contains("\"command\":\"configurationDone\"", configDoneResponse);
-
-                // Welcome message should appear
-                var welcomeMsg = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
-                Assert.Contains("\"event\":\"output\"", welcomeMsg);
-                Assert.Contains("Actions Debug Console", welcomeMsg);
-
-                // Second configurationDone — should NOT produce another welcome message
-                await SendRequestAsync(stream, new Request
-                {
-                    Seq = 2,
-                    Type = "request",
-                    Command = "configurationDone"
-                });
-
-                var secondResponse = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
-                Assert.Contains("\"command\":\"configurationDone\"", secondResponse);
-
-                // Next message should be threads response, not another welcome output
-                await SendRequestAsync(stream, new Request
-                {
-                    Seq = 3,
-                    Type = "request",
-                    Command = "threads"
-                });
-
-                var threadsResponse = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
-                Assert.Contains("\"command\":\"threads\"", threadsResponse);
-
-                await _debugger.StopAsync();
-            }
-        }
     }
 }

src/Test/L0/Worker/DapReplExecutorL0.cs

@@ -5,12 +5,9 @@ using System.Threading;
 using System.Threading.Tasks;
 using GitHub.DistributedTask.Expressions2;
 using GitHub.DistributedTask.Pipelines.ContextData;
-using GitHub.DistributedTask.WebApi;
 using GitHub.Runner.Common.Tests;
 using GitHub.Runner.Worker;
-using GitHub.Runner.Worker.Container;
 using GitHub.Runner.Worker.Dap;
-using GitHub.Runner.Worker.Handlers;
 using Moq;
 using Xunit;
 
@@ -43,8 +40,7 @@ namespace GitHub.Runner.Common.Tests.Worker
 
         private Mock<IExecutionContext> CreateMockContext(
             DictionaryContextData exprValues = null,
-            IDictionary<string, IDictionary<string, string>> jobDefaults = null,
-            ContainerInfo container = null)
+            IDictionary<string, IDictionary<string, string>> jobDefaults = null)
         {
             var mock = new Mock<IExecutionContext>();
             mock.Setup(x => x.ExpressionValues).Returns(exprValues ?? new DictionaryContextData());
@@ -55,7 +51,6 @@ namespace GitHub.Runner.Common.Tests.Worker
                 PrependPath = new List<string>(),
                 JobDefaults = jobDefaults
                     ?? new Dictionary<string, IDictionary<string, string>>(StringComparer.OrdinalIgnoreCase),
-                Container = container,
             };
             mock.Setup(x => x.Global).Returns(global);
 
@@ -70,7 +65,7 @@ namespace GitHub.Runner.Common.Tests.Worker
             using (CreateTestContext())
             {
                 var command = new RunCommand { Script = "echo hello" };
-                var result = await _executor.ExecuteRunCommandAsync(command, null, false, CancellationToken.None);
+                var result = await _executor.ExecuteRunCommandAsync(command, null, CancellationToken.None);
 
                 Assert.Equal("error", result.Type);
                 Assert.Contains("No execution context available", result.Result);
@@ -238,101 +233,5 @@ namespace GitHub.Runner.Common.Tests.Worker
                 Assert.False(result.ContainsKey("BAZ"));
             }
         }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void CreateStepHost_NoContainer_ReturnsDefaultStepHost()
-        {
-            using (var hc = CreateTestContext())
-            {
-                hc.EnqueueInstance<IDefaultStepHost>(new DefaultStepHost());
-                var context = CreateMockContext();
-                var result = _executor.CreateStepHost(context.Object, isActionStep: true);
-
-                Assert.IsType<DefaultStepHost>(result);
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void CreateStepHost_WithContainer_ActionStep_ReturnsContainerStepHost()
-        {
-            using (var hc = CreateTestContext())
-            {
-                hc.EnqueueInstance<IContainerStepHost>(new ContainerStepHost());
-                var container = new ContainerInfo { ContainerId = "abc123" };
-                var context = CreateMockContext(container: container);
-                var result = _executor.CreateStepHost(context.Object, isActionStep: true);
-
-                Assert.IsType<ContainerStepHost>(result);
-                var containerHost = (ContainerStepHost)result;
-                Assert.Same(container, containerHost.Container);
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void CreateStepHost_WithContainer_InfrastructureStep_ReturnsDefaultStepHost()
-        {
-            using (var hc = CreateTestContext())
-            {
-                hc.EnqueueInstance<IDefaultStepHost>(new DefaultStepHost());
-                var container = new ContainerInfo { ContainerId = "abc123" };
-                var context = CreateMockContext(container: container);
-                var result = _executor.CreateStepHost(context.Object, isActionStep: false);
-
-                Assert.IsType<DefaultStepHost>(result);
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void CreateStepHost_ContainerWithoutId_NoHooks_ReturnsDefaultStepHost()
-        {
-            using (var hc = CreateTestContext())
-            {
-                hc.EnqueueInstance<IDefaultStepHost>(new DefaultStepHost());
-                // Container exists but hasn't been started yet (no ContainerId)
-                var container = new ContainerInfo();
-                var context = CreateMockContext(container: container);
-                var result = _executor.CreateStepHost(context.Object, isActionStep: true);
-
-                Assert.IsType<DefaultStepHost>(result);
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void CreateStepHost_ContainerWithoutId_HooksEnabled_ReturnsContainerStepHost()
-        {
-            using (var hc = CreateTestContext())
-            {
-                hc.EnqueueInstance<IContainerStepHost>(new ContainerStepHost());
-                // Container hooks need both the feature flag and the env var
-                Environment.SetEnvironmentVariable("ACTIONS_RUNNER_CONTAINER_HOOKS", "/some/hook/path");
-                try
-                {
-                    var container = new ContainerInfo();
-                    var context = CreateMockContext(container: container);
-                    context.Object.Global.Variables = new Variables(
-                        hc,
-                        new Dictionary<string, VariableValue>
-                        {
-                            { Constants.Runner.Features.AllowRunnerContainerHooks, new VariableValue("true") }
-                        });
-                    var result = _executor.CreateStepHost(context.Object, isActionStep: true);
-                    Assert.IsAssignableFrom<IContainerStepHost>(result);
-                }
-                finally
-                {
-                    Environment.SetEnvironmentVariable("ACTIONS_RUNNER_CONTAINER_HOOKS", null);
-                }
-            }
-        }
     }
 }

src/Test/L0/Worker/YamlScalarFormatterL0.cs

@@ -1,119 +0,0 @@
-using System;
-using System.Collections.Generic;
-using GitHub.Runner.Worker.Dap;
-using Xunit;
-using YamlDotNet.Serialization;
-
-namespace GitHub.Runner.Common.Tests.Worker
-{
-    public sealed class YamlScalarFormatterL0
-    {
-        private static readonly IDeserializer Deserializer = new DeserializerBuilder().Build();
-
-        // Embed the formatter output inside a minimal YAML mapping and
-        // round-trip through YamlDotNet, asserting the parsed value equals
-        // the original input. Decouples assertions from the emitter's
-        // quoting choices (plain vs single- vs double-quoted).
-        private static void AssertRoundTrips(string value)
-        {
-            string scalar = YamlScalarFormatter.Format(value);
-            string yaml = $"k: {scalar}\n";
-
-            Dictionary<string, object> doc;
-            try
-            {
-                doc = Deserializer.Deserialize<Dictionary<string, object>>(yaml);
-            }
-            catch (Exception ex)
-            {
-                throw new Xunit.Sdk.XunitException(
-                    $"Formatted scalar did not round-trip as valid YAML.\nInput: '{value}'\nFormatted: '{scalar}'\nFull YAML:\n{yaml}\nError: {ex}");
-            }
-            Assert.NotNull(doc);
-            Assert.True(doc.ContainsKey("k"), $"missing key in parsed doc. Formatted: '{scalar}'");
-            Assert.Equal(value, doc["k"] as string);
-        }
-
-        [Theory]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        [InlineData("hello")]
-        [InlineData("with: colon")]
-        [InlineData("with#hash")]
-        [InlineData(" leading")]
-        [InlineData("trailing ")]
-        [InlineData("a\"b")]
-        [InlineData("a\\b")]
-        [InlineData("@at")]
-        [InlineData("*star")]
-        [InlineData("&amp")]
-        [InlineData("?question")]
-        [InlineData("!exclaim")]
-        [InlineData("- dash")]
-        [InlineData("{brace}")]
-        [InlineData("[bracket]")]
-        public void Format_RoundTripsThroughYamlDeserializer(string value)
-        {
-            // The formatter must produce output that, embedded under a key,
-            // parses back to exactly the input. The emitter is free to
-            // pick plain, single-quoted, or double-quoted style.
-            AssertRoundTrips(value);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Format_PlainAscii_NoQuotingNeeded()
-        {
-            // Sanity check that the simple case stays plain.
-            Assert.Equal("hello", YamlScalarFormatter.Format("hello"));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Format_NoTrailingNewline()
-        {
-            Assert.False(YamlScalarFormatter.Format("hello").EndsWith("\n"));
-            Assert.False(YamlScalarFormatter.Format("with: colon").EndsWith("\n"));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Format_NoDocumentMarkers()
-        {
-            // The emitter wraps the scalar in a document; the formatter
-            // must strip both `--- ` (with space) and `---\n` (on its
-            // own line) prefixes plus the `\n...` suffix.
-            Assert.DoesNotContain("---", YamlScalarFormatter.Format("hello"));
-            Assert.DoesNotContain("...", YamlScalarFormatter.Format("hello"));
-            // Empty string is one of the cases where the emitter does
-            // produce a document marker by default.
-            Assert.DoesNotContain("---", YamlScalarFormatter.Format(""));
-            Assert.DoesNotContain("...", YamlScalarFormatter.Format(""));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Format_AlwaysUsesLfLineBreaks()
-        {
-            // Regression: YamlDotNet's Emitter calls WriteLine, which on
-            // Windows produces CRLF (the host's Environment.NewLine).
-            // Format must force LF so the output round-trips regardless
-            // of platform.
-            Assert.DoesNotContain('\r', YamlScalarFormatter.Format("hello"));
-            Assert.DoesNotContain('\r', YamlScalarFormatter.Format("with: colon"));
-            Assert.DoesNotContain('\r', YamlScalarFormatter.Format(""));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Format_NullValue_Throws()
-        {
-            Assert.Throws<ArgumentNullException>(() => YamlScalarFormatter.Format(null));
-        }
-    }
-}

src/dev.sh

@@ -17,7 +17,7 @@ LAYOUT_DIR="$SCRIPT_DIR/../_layout"
 DOWNLOAD_DIR="$SCRIPT_DIR/../_downloads/netcore2x"
 PACKAGE_DIR="$SCRIPT_DIR/../_package"
 DOTNETSDK_ROOT="$SCRIPT_DIR/../_dotnetsdk"
-DOTNETSDK_VERSION="8.0.421"
+DOTNETSDK_VERSION="8.0.420"
 DOTNETSDK_INSTALLDIR="$DOTNETSDK_ROOT/$DOTNETSDK_VERSION"
 RUNNER_VERSION=$(cat runnerversion)
 

src/global.json

@@ -1,5 +1,5 @@
 {
   "sdk": {
-    "version": "8.0.421"
+    "version": "8.0.420"
   }
 }