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

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

@@ -16,10 +16,19 @@ using Microsoft.DevTunnels.Connections;
 using Microsoft.DevTunnels.Contracts;
 using Microsoft.DevTunnels.Management;
 using Newtonsoft.Json;
-using Pipelines = GitHub.DistributedTask.Pipelines;
 
 namespace GitHub.Runner.Worker.Dap
 {
+    /// <summary>
+    /// Stores information about a completed step for stack trace display.
+    /// </summary>
+    internal sealed class CompletedStepInfo
+    {
+        public string DisplayName { get; set; }
+        public TaskResult? Result { get; set; }
+        public int FrameId { get; set; }
+    }
+
     /// <summary>
     /// Single public facade for the Debug Adapter Protocol subsystem.
     /// Owns the full transport, handshake, step-level pauses, variable
@@ -42,12 +51,8 @@ namespace GitHub.Runner.Worker.Dap
         // Frame ID for the current step (always 1)
         private const int _currentFrameId = 1;
 
-        // Frame ID for the static "job" frame anchored at line 1 of the execution view.
-        private const int _jobFrameId = 2;
-
-        // MVP serves a single synthesized source per session (the job's execution view).
-        // Stable session-scoped ID 1; future sources (composite step-in) will use higher IDs.
-        private const int _executionViewSourceReference = 1;
+        // Frame IDs for completed steps start at 1000
+        private const int _completedFrameIdBase = 1000;
 
         private TcpListener _listener;
         private TcpClient _client;
@@ -87,6 +92,11 @@ namespace GitHub.Runner.Worker.Dap
         // Current execution context
         private IStep _currentStep;
         private IExecutionContext _jobContext;
+        private int _currentStepIndex;
+
+        // Track completed steps for stack trace
+        private readonly List<CompletedStepInfo> _completedSteps = new List<CompletedStepInfo>();
+        private int _nextCompletedFrameId = _completedFrameIdBase;
 
         // Client connection tracking for reconnection support
         private volatile bool _isClientConnected;
@@ -97,8 +107,6 @@ namespace GitHub.Runner.Worker.Dap
         // REPL command executor for run() commands
         private DapReplExecutor _replExecutor;
 
-        private JobExecutionView _executionView;
-
         public bool IsActive =>
             _state == DapSessionState.Ready ||
             _state == DapSessionState.Paused ||
@@ -251,8 +259,7 @@ namespace GitHub.Runner.Worker.Dap
                     }
                     catch (Exception ex)
                     {
-                        Trace.Warning("DAP job-completed pause error.");
-                        Trace.Error(ex);
+                        Trace.Warning($"DAP job-completed pause error: {ex.Message}");
                     }
                 }
 
@@ -262,8 +269,7 @@ namespace GitHub.Runner.Worker.Dap
                 }
                 catch (Exception ex)
                 {
-                    Trace.Warning("DAP OnJobCompleted error.");
-                    Trace.Error(ex);
+                    Trace.Warning($"DAP OnJobCompleted error: {ex.Message}");
                 }
             }
         }
@@ -380,8 +386,7 @@ namespace GitHub.Runner.Worker.Dap
             }
             catch (Exception ex)
             {
-                Trace.Warning("DAP OnStepStarting error.");
-                Trace.Error(ex);
+                Trace.Warning($"DAP OnStepStarting error: {ex.Message}");
             }
         }
 
@@ -394,8 +399,10 @@ namespace GitHub.Runner.Worker.Dap
 
             try
             {
+                var result = step.ExecutionContext?.Result;
                 Trace.Info("Step completed");
-                JobExecutionView view;
+
+                // Add to completed steps list for stack trace
                 lock (_stateLock)
                 {
                     if (_state != DapSessionState.Ready &&
@@ -405,353 +412,20 @@ namespace GitHub.Runner.Worker.Dap
                         return;
                     }
 
-                    // Clear current-step ref if it matches; otherwise leave alone
-                    // (defensive — OnStepStartingAsync may have already advanced it).
-                    if (ReferenceEquals(_currentStep, step))
+                    _completedSteps.Add(new CompletedStepInfo
                     {
-                        _currentStep = null;
-                    }
-                    view = _executionView;
-                }
-
-                // If the skipped step was a Main IActionRunner with a predicted
-                // Post-step placeholder, mark that placeholder as skipped so
-                // the view does not advertise a step that will never run.
-                if (view != null &&
-                    step is IActionRunner actionRunner &&
-                    actionRunner.Stage == ActionRunStage.Main &&
-                    actionRunner.Action != null &&
-                    step.ExecutionContext?.Result == TaskResult.Skipped)
-                {
-                    var matchKey = MatchKeyFor(actionRunner.Action.Id);
-                    if (view.TryMarkSkipped(matchKey))
-                    {
-                        SendLoadedSourceEvent("changed");
-                    }
+                        DisplayName = step.DisplayName,
+                        Result = result,
+                        FrameId = _nextCompletedFrameId++
+                    });
                 }
             }
             catch (Exception ex)
             {
-                Trace.Warning("DAP OnStepCompleted error.");
-                Trace.Error(ex);
+                Trace.Warning($"DAP OnStepCompleted error: {ex.Message}");
             }
         }
 
-        /// <summary>
-        /// Snapshot of the current job execution view, or null if it has not
-        /// been built yet (debugger inactive, or InitializeJob has not yet
-        /// signalled). Phase 2c will consume this for DAP source/stack-trace
-        /// responses.
-        /// </summary>
-        internal JobExecutionView ExecutionView
-        {
-            get
-            {
-                lock (_stateLock)
-                {
-                    return _executionView;
-                }
-            }
-        }
-
-        public async Task OnJobStepsInitializedAsync(IEnumerable<IStep> mainQueue, IEnumerable<IStep> initialPostStack)
-        {
-            if (!IsActive)
-            {
-                return;
-            }
-
-            try
-            {
-                IExecutionContext jobContext;
-                lock (_stateLock)
-                {
-                    jobContext = _jobContext;
-                }
-
-                string jobId = jobContext?.GetGitHubContext("job");
-                if (string.IsNullOrWhiteSpace(jobId))
-                {
-                    jobId = "job";
-                }
-
-                // Materialize mainQueue once so we can iterate it twice
-                // (once for entries, once for the post-step predictor).
-                var mainSteps = mainQueue == null ? new List<IStep>() : new List<IStep>(mainQueue);
-
-                var entries = new List<(JobExecutionViewEntry entry, IStep stepIdentity)>();
-                foreach (var step in mainSteps)
-                {
-                    var entry = StepEntryTranslator.TryTranslate(step);
-                    if (entry != null)
-                    {
-                        entries.Add((entry, step));
-                    }
-                }
-                // Stack<T>.GetEnumerator() yields items in LIFO order — the
-                // same order callers will pop them. We materialize them into
-                // the view in that pop order so post-step entries appear in
-                // execution order.
-                if (initialPostStack != null)
-                {
-                    foreach (var step in initialPostStack)
-                    {
-                        var entry = StepEntryTranslator.TryTranslate(step);
-                        if (entry != null)
-                        {
-                            entries.Add((entry, step));
-                        }
-                    }
-                }
-
-                var view = new JobExecutionView(jobId);
-                if (entries.Count > 0)
-                {
-                    view.AppendRange(entries);
-                }
-
-                // Predict Post-step placeholders for actions that declare
-                // HasPost in their action manifest. Walking Pre+Main runners
-                // in declaration order, then prepending each prediction so
-                // the rendered post section matches the runner's LIFO
-                // post-execution order (the runner's post stack pops in
-                // reverse-registration order). Wrapped in a try/catch so a
-                // missing IActionManager or LoadAction failure cannot
-                // prevent the view from being published.
-                try
-                {
-                    PredictPostPlaceholders(jobContext, mainSteps, view);
-                }
-                catch (Exception ex)
-                {
-                    Trace.Warning("DAP predictor: predicting post placeholders failed; continuing without predictions.");
-                    Trace.Error(ex);
-                }
-
-                lock (_stateLock)
-                {
-                    _executionView = view;
-                }
-
-                Trace.Info($"DAP execution view initialized with {view.EntryCount} entries.");
-                SendLoadedSourceEvent("new");
-            }
-            catch (Exception ex)
-            {
-                Trace.Warning("DAP OnJobStepsInitialized error.");
-                Trace.Error(ex);
-            }
-
-            await Task.CompletedTask;
-        }
-
-        public void OnPostStepRegistered(IStep step)
-        {
-            if (!IsActive || step == null)
-            {
-                return;
-            }
-
-            try
-            {
-                JobExecutionView view;
-                lock (_stateLock)
-                {
-                    view = _executionView;
-                }
-
-                if (view == null)
-                {
-                    return;
-                }
-
-                // Try to claim a previously-predicted placeholder. When
-                // OnJobStepsInitializedAsync ran, we walked the Pre+Main
-                // queue and synthesized a Post placeholder for every action
-                // whose manifest declared HasPost. If this registration
-                // matches one of those placeholders by Action.Id, claim it
-                // in place — no view growth, no `loadedSource changed`
-                // event needed.
-                if (step is IActionRunner postRunner && postRunner.Action != null)
-                {
-                    var matchKey = MatchKeyFor(postRunner.Action.Id);
-                    if (view.TryClaim(matchKey, step).HasValue)
-                    {
-                        return;
-                    }
-                }
-
-                // Unpredicted path: composite-action JIT post discovery,
-                // container hooks, or any other registration we did not
-                // foresee at view-build time. Fall back to append + notify
-                // clients via `loadedSource changed`.
-                var entry = StepEntryTranslator.TryTranslate(step);
-                if (entry == null)
-                {
-                    return;
-                }
-
-                try
-                {
-                    view.Append(entry, step);
-                    SendLoadedSourceEvent("changed");
-                }
-                catch (InvalidOperationException ex)
-                {
-                    // Step already registered — RegisterPostJobStep tolerates
-                    // duplicate registrations in some workflow shapes; mirror
-                    // that semantics here so we don't propagate.
-                    Trace.Info($"DAP OnPostStepRegistered: duplicate step ignored ({ex.Message}).");
-                }
-            }
-            catch (Exception ex)
-            {
-                Trace.Warning("DAP OnPostStepRegistered error.");
-                Trace.Error(ex);
-            }
-        }
-
-        /// <summary>
-        /// Walks <paramref name="mainSteps"/> (the queue of Pre+Main
-        /// IActionRunners produced by JobRunner) and synthesizes a Post
-        /// placeholder entry on <paramref name="view"/> for every action
-        /// whose manifest declares <c>HasPost = true</c>.
-        ///
-        /// Conditions mirror <c>ActionRunner.RunAsync</c> exactly:
-        /// the runner is in Pre or Main stage, the action is a
-        /// <see cref="Pipelines.RepositoryPathReference"/> that is NOT the
-        /// self-repository alias, the action is not a script, and the
-        /// resolved <see cref="Definition"/> reports HasPost.
-        ///
-        /// Predictions are collected in declaration order, then APPENDED
-        /// in reverse so the rendered post section mirrors the runner's
-        /// LIFO post-execution order (the runner's post stack pops in
-        /// reverse-registration order — see ExecutionContext.RegisterPostJobStep).
-        /// </summary>
-        private void PredictPostPlaceholders(IExecutionContext jobContext, IReadOnlyList<IStep> mainSteps, JobExecutionView view)
-        {
-            if (jobContext == null || mainSteps == null || mainSteps.Count == 0 || view == null)
-            {
-                return;
-            }
-
-            IActionManager actionManager;
-            try
-            {
-                actionManager = HostContext.GetService<IActionManager>();
-            }
-            catch (Exception ex)
-            {
-                Trace.Info($"DAP predictor: IActionManager unavailable ({ex.Message}); skipping post-step prediction.");
-                return;
-            }
-
-            var predictions = new List<(JobExecutionViewEntry entry, string matchKey)>();
-            var seenActionIds = new HashSet<Guid>();
-
-            foreach (var step in mainSteps)
-            {
-                if (step is not IActionRunner runner)
-                {
-                    continue;
-                }
-                if (runner.Stage == ActionRunStage.Post)
-                {
-                    // Post entries are already seeded from initialPostStack.
-                    continue;
-                }
-                var action = runner.Action;
-                if (action == null)
-                {
-                    continue;
-                }
-                // ActionRunner.cs:113 — Post only created when the action is
-                // a RepositoryPathReference that is not the self-repository
-                // alias and not a script.
-                if (action.Reference is not Pipelines.RepositoryPathReference repoRef)
-                {
-                    continue;
-                }
-                if (string.Equals(repoRef.RepositoryType, Pipelines.PipelineConstants.SelfAlias, StringComparison.OrdinalIgnoreCase))
-                {
-                    continue;
-                }
-                // (A RepositoryPathReference is never a script — script
-                // run-steps surface as a different ActionStepDefinitionReference
-                // subclass, so the cast above already filtered them out.)
-                // Dedupe by Action.Id: the runtime dedups via
-                // Root.StepsWithPostRegistered.Add(actionRunner.Action.Id),
-                // so two steps referencing the same Action.Id only ever
-                // register one Post. Mirror that here so we don't synthesize
-                // two placeholders for one future registration.
-                if (!seenActionIds.Add(action.Id))
-                {
-                    continue;
-                }
-
-                Definition definition;
-                try
-                {
-                    definition = actionManager.LoadAction(jobContext, action);
-                }
-                catch (Exception ex)
-                {
-                    Trace.Info($"DAP predictor: LoadAction failed for {repoRef.Name} ({ex.Message}); skipping prediction.");
-                    continue;
-                }
-
-                if (definition?.Data?.Execution?.HasPost != true)
-                {
-                    continue;
-                }
-
-                // Compute the Post display name exactly as ActionRunner does
-                // when it constructs the Post IActionRunner (ActionRunner.cs:115-122).
-                var displayName = runner.DisplayName;
-                if (string.IsNullOrEmpty(displayName))
-                {
-                    displayName = "step";
-                }
-                if (runner.Stage == ActionRunStage.Pre &&
-                    displayName.StartsWith("Pre ", StringComparison.OrdinalIgnoreCase))
-                {
-                    displayName = displayName.Substring("Pre ".Length);
-                }
-                var postDisplayName = $"Post {displayName}";
-
-                var entry = new JobExecutionViewEntry(
-                    phase: JobExecutionPhase.Post,
-                    displayName: postDisplayName,
-                    uses: StepEntryTranslator.FormatActionReference(action.Reference));
-
-                predictions.Add((entry, MatchKeyFor(action.Id)));
-            }
-
-            // Reverse declaration order so the rendered post section
-            // matches the LIFO order in which the runner will pop posts.
-            predictions.Reverse();
-
-            foreach (var (entry, key) in predictions)
-            {
-                try
-                {
-                    view.Append(entry, stepIdentity: null, matchKey: key);
-                }
-                catch (Exception ex)
-                {
-                    Trace.Warning("DAP predictor: failed to append Post placeholder; skipping.");
-                    Trace.Error(ex);
-                }
-            }
-        }
-
-        // Stable, opaque key derived from an action's Pipelines.ActionStep.Id.
-        // All IActionRunner instances for the same action (Pre/Main/Post)
-        // share the same Action reference (see ActionRunner.cs:131), so the
-        // Id is constant across phases and is the right join key.
-        private static string MatchKeyFor(Guid actionId) =>
-            $"post:{actionId:N}";
-
         internal async Task HandleMessageAsync(string messageJson, CancellationToken cancellationToken)
         {
             Request request = null;
@@ -793,8 +467,6 @@ namespace GitHub.Runner.Worker.Dap
                         "next" => HandleNext(request),
                         "setBreakpoints" => HandleSetBreakpoints(request),
                         "setExceptionBreakpoints" => HandleSetExceptionBreakpoints(request),
-                        "source" => HandleSource(request),
-                        "loadedSources" => HandleLoadedSources(request),
                         "completions" => HandleCompletions(request),
                         "stepIn" => CreateResponse(request, false, "Step In is not supported. Actions jobs debug at the step level - use 'next' to advance to the next step.", body: null),
                         "stepOut" => CreateResponse(request, false, "Step Out is not supported. Actions jobs debug at the step level - use 'continue' to resume.", body: null),
@@ -1148,7 +820,7 @@ namespace GitHub.Runner.Worker.Dap
 
         internal async Task OnStepStartingAsync(IStep step, bool isFirstStep)
         {
-            bool shouldPause;
+            bool pauseOnNextStep;
             CancellationToken cancellationToken;
             lock (_stateLock)
             {
@@ -1160,14 +832,18 @@ namespace GitHub.Runner.Worker.Dap
                 }
 
                 _currentStep = step;
+                _currentStepIndex = _completedSteps.Count;
+                pauseOnNextStep = _pauseOnNextStep;
                 cancellationToken = _jobContext?.CancellationToken ?? CancellationToken.None;
-                shouldPause = ShouldPauseBefore(step, isFirstStep);
             }
 
             // Reset variable references so stale nested refs from the
             // previous step are not served to the client.
             _variableProvider?.Reset();
 
+            // Determine if we should pause
+            bool shouldPause = isFirstStep || pauseOnNextStep;
+
             if (!shouldPause)
             {
                 Trace.Info("Step starting without debugger pause");
@@ -1188,29 +864,6 @@ namespace GitHub.Runner.Worker.Dap
             await WaitForCommandAsync(cancellationToken);
         }
 
-        /// <summary>
-        /// Decides whether the debugger should pause before <paramref name="step"/>.
-        /// Today: pause on the first step always; otherwise pause when the user
-        /// has elected step-mode (the 'next' command). Future breakpoint support
-        /// will be a single additional check here against a per-step breakpoint set.
-        /// Caller MUST hold <c>_stateLock</c>.
-        /// </summary>
-        private bool ShouldPauseBefore(IStep step, bool isFirstStep)
-        {
-            if (isFirstStep)
-            {
-                return true;
-            }
-
-            if (_pauseOnNextStep)
-            {
-                return true;
-            }
-
-            // TODO Phase 2c+1: if (_breakpointSet.Contains(step)) return true;
-            return false;
-        }
-
         internal void OnJobCompleted()
         {
             Trace.Info("Job completed, sending terminated event");
@@ -1282,7 +935,7 @@ namespace GitHub.Runner.Worker.Dap
                 SupportsTerminateRequest = false,
                 SupportTerminateDebuggee = false,
                 SupportsDelayedStackTraceLoading = false,
-                SupportsLoadedSourcesRequest = true,
+                SupportsLoadedSourcesRequest = false,
                 SupportsProgressReporting = false,
                 SupportsRunInTerminalRequest = false,
                 SupportsCancelRequest = false,
@@ -1356,155 +1009,72 @@ namespace GitHub.Runner.Worker.Dap
             return CreateResponse(request, true, body: body);
         }
 
-        internal Response HandleStackTrace(Request request)
+        private Response HandleStackTrace(Request request)
         {
             IStep currentStep;
-            JobExecutionView view;
+            int currentStepIndex;
+            CompletedStepInfo[] completedSteps;
             lock (_stateLock)
             {
                 currentStep = _currentStep;
-                view = _executionView;
+                currentStepIndex = _currentStepIndex;
+                completedSteps = _completedSteps.ToArray();
             }
 
             var frames = new List<StackFrame>();
 
-            if (view != null)
+            // Add current step as the top frame
+            if (currentStep != null)
             {
-                var source = BuildExecutionViewSource(view.JobId);
+                var resultIndicator = currentStep.ExecutionContext?.Result != null
+                    ? $" [{currentStep.ExecutionContext.Result}]"
+                    : " [running]";
 
-                // Frame 0: the currently-executing step (only when one is set).
-                if (currentStep != null)
-                {
-                    var stepLine = view.TryGetLineForStep(currentStep) ?? 1;
-                    frames.Add(new StackFrame
-                    {
-                        Id = _currentFrameId,
-                        Name = MaskUserVisibleText(currentStep.DisplayName ?? "step"),
-                        Line = stepLine,
-                        Column = 1,
-                        Source = source,
-                        PresentationHint = "normal",
-                    });
-                }
-
-                // Frame 1: the job (anchors the stack; line 1 = the synthesized header).
-                frames.Add(new StackFrame
-                {
-                    Id = _jobFrameId,
-                    Name = MaskUserVisibleText($"job: {view.JobId}"),
-                    Line = 1,
-                    Column = 1,
-                    Source = source,
-                    PresentationHint = "subtle",
-                });
-            }
-            else if (currentStep != null)
-            {
-                // Defensive: view not yet built but a step is executing.
-                // Still emit a single frame with no Source so the client doesn't choke.
                 frames.Add(new StackFrame
                 {
                     Id = _currentFrameId,
-                    Name = MaskUserVisibleText(currentStep.DisplayName ?? "step"),
+                    Name = MaskUserVisibleText($"{currentStep.DisplayName ?? "Current Step"}{resultIndicator}"),
+                    Line = currentStepIndex + 1,
+                    Column = 1,
+                    PresentationHint = "normal"
+                });
+            }
+            else
+            {
+                frames.Add(new StackFrame
+                {
+                    Id = _currentFrameId,
+                    Name = "(no step executing)",
+                    Line = 0,
+                    Column = 1,
+                    PresentationHint = "subtle"
+                });
+            }
+
+            // Add completed steps as additional frames (most recent first)
+            for (int i = completedSteps.Length - 1; i >= 0; i--)
+            {
+                var completedStep = completedSteps[i];
+                var resultStr = completedStep.Result.HasValue ? $" [{completedStep.Result}]" : "";
+                frames.Add(new StackFrame
+                {
+                    Id = completedStep.FrameId,
+                    Name = MaskUserVisibleText($"{completedStep.DisplayName}{resultStr}"),
                     Line = 1,
                     Column = 1,
-                    PresentationHint = "normal",
+                    PresentationHint = "subtle"
                 });
             }
 
             var body = new StackTraceResponseBody
             {
                 StackFrames = frames,
-                TotalFrames = frames.Count,
+                TotalFrames = frames.Count
             };
 
             return CreateResponse(request, true, body: body);
         }
 
-        /// <summary>
-        /// Builds the synthesized job execution view <see cref="Source"/> descriptor.
-        /// All frames in a session share one Source; the client retrieves its
-        /// content via the DAP <c>source</c> request keyed by <see cref="_executionViewSourceReference"/>.
-        /// </summary>
-        private Source BuildExecutionViewSource(string jobId)
-        {
-            return new Source
-            {
-                Name = MaskUserVisibleText("execution.yml"),
-                Path = MaskUserVisibleText($"{jobId}/execution.yml"),
-                SourceReference = _executionViewSourceReference,
-                PresentationHint = "normal",
-            };
-        }
-
-        internal Response HandleSource(Request request)
-        {
-            SourceArguments args;
-            try
-            {
-                args = request.Arguments?.ToObject<SourceArguments>();
-            }
-            catch (Exception ex)
-            {
-                Trace.Warning($"Failed to parse source arguments: {ex.GetType().Name}");
-                return CreateResponse(request, false, "Invalid source arguments.", body: null);
-            }
-
-            if (args == null)
-            {
-                return CreateResponse(request, false, "Missing source arguments.", body: null);
-            }
-
-            JobExecutionView view;
-            lock (_stateLock)
-            {
-                view = _executionView;
-            }
-
-            if (view == null)
-            {
-                return CreateResponse(request, false, "Execution view not yet available.", body: null);
-            }
-
-            if (args.SourceReference != _executionViewSourceReference)
-            {
-                return CreateResponse(request, false, $"Unknown source reference: {args.SourceReference}.", body: null);
-            }
-
-            var body = new SourceResponseBody
-            {
-                Content = MaskUserVisibleText(view.Yaml),
-                // MimeType intentionally unset: VS Code's debug content provider
-                // short-circuits language detection on the response's mimeType
-                // (exact-match against its registered language mimetypes) and
-                // falls back to plaintext on unknown values. The IANA YAML type
-                // "application/yaml" is not in VS Code's table (it only knows
-                // the legacy "text/x-yaml" synthesized for the built-in YAML
-                // language contribution). By omitting mimeType, clients fall
-                // through to path-extension detection — `.yml` in Source.Path
-                // is the universal mechanism every DAP client honors
-                // consistently (VS Code, nvim-dap, JetBrains).
-            };
-
-            return CreateResponse(request, true, body: body);
-        }
-
-        internal Response HandleLoadedSources(Request request)
-        {
-            JobExecutionView view;
-            lock (_stateLock)
-            {
-                view = _executionView;
-            }
-
-            var body = new LoadedSourcesResponseBody();
-            if (view != null)
-            {
-                body.Sources.Add(BuildExecutionViewSource(view.JobId));
-            }
-            return CreateResponse(request, true, body: body);
-        }
-
         private Response HandleScopes(Request request)
         {
             var args = request.Arguments?.ToObject<ScopesArguments>();
@@ -1720,40 +1290,11 @@ namespace GitHub.Runner.Worker.Dap
             return CreateResponse(request, true, body: null);
         }
 
-        internal Response HandleSetBreakpoints(Request request)
+        private Response HandleSetBreakpoints(Request request)
         {
-            SetBreakpointsArguments args = null;
-            try
-            {
-                args = request.Arguments?.ToObject<SetBreakpointsArguments>();
-            }
-            catch (Exception ex)
-            {
-                Trace.Warning($"Failed to parse setBreakpoints arguments: {ex.GetType().Name}");
-            }
-
-            JobExecutionView view;
-            lock (_stateLock)
-            {
-                view = _executionView;
-            }
-
-            var body = new SetBreakpointsResponseBody();
-            if (args?.Breakpoints != null && view != null)
-            {
-                var source = BuildExecutionViewSource(view.JobId);
-                foreach (var requested in args.Breakpoints)
-                {
-                    body.Breakpoints.Add(new Breakpoint
-                    {
-                        Verified = false,
-                        Line = requested.Line,
-                        Source = source,
-                        Message = "Breakpoint support is coming in a future runner release. The debugger currently pauses at every step boundary; use 'continue' to advance.",
-                    });
-                }
-            }
-            return CreateResponse(request, true, body: body);
+            // MVP: acknowledge but don't process breakpoints
+            // All steps pause automatically via _pauseOnNextStep
+            return CreateResponse(request, true, body: new { breakpoints = Array.Empty<object>() });
         }
 
         private Response HandleSetExceptionBreakpoints(Request request)
@@ -1818,7 +1359,8 @@ namespace GitHub.Runner.Worker.Dap
 
         /// <summary>
         /// Resolves the execution context for a given stack frame ID.
-        /// Frame 1 = current step; frame 2 = job-level (subtle anchor frame).
+        /// Frame 1 = current step; frames 1000+ = completed steps (no
+        /// context available - those steps have already finished).
         /// Falls back to the job-level context when no step is active.
         /// </summary>
         private IExecutionContext GetExecutionContextForFrame(int frameId)
@@ -1828,7 +1370,7 @@ namespace GitHub.Runner.Worker.Dap
                 return GetCurrentExecutionContext();
             }
 
-            // Job/anchor frame — no step-level context.
+            // Completed-step frames don't carry a live execution context.
             return null;
         }
 
@@ -1865,33 +1407,6 @@ namespace GitHub.Runner.Worker.Dap
             });
         }
 
-        /// <summary>
-        /// Sends a loadedSource event with the current execution view's source.
-        /// No-op if the view has not been built yet.
-        /// </summary>
-        private void SendLoadedSourceEvent(string reason)
-        {
-            JobExecutionView view;
-            lock (_stateLock)
-            {
-                view = _executionView;
-            }
-            if (view == null)
-            {
-                return;
-            }
-
-            SendEvent(new Event
-            {
-                EventType = "loadedSource",
-                Body = new LoadedSourceEventBody
-                {
-                    Reason = reason,
-                    Source = BuildExecutionViewSource(view.JobId),
-                },
-            });
-        }
-
         private string MaskUserVisibleText(string value)
         {
             if (string.IsNullOrEmpty(value))

src/Runner.Worker/Dap/DapMessages.cs

@@ -537,132 +537,6 @@ namespace GitHub.Runner.Worker.Dap
 
     #endregion
 
-    #region Source Request/Response
-
-    /// <summary>
-    /// Arguments for 'source' request.
-    /// </summary>
-    public class SourceArguments
-    {
-        /// <summary>
-        /// Source descriptor (optional, redundant with sourceReference).
-        /// </summary>
-        [JsonProperty("source", NullValueHandling = NullValueHandling.Ignore)]
-        public Source Source { get; set; }
-
-        /// <summary>
-        /// The reference to the source. Required by DAP spec.
-        /// </summary>
-        [JsonProperty("sourceReference")]
-        public int SourceReference { get; set; }
-    }
-
-    /// <summary>
-    /// Response body for 'source' request.
-    /// </summary>
-    public class SourceResponseBody
-    {
-        /// <summary>
-        /// Content of the source as a string.
-        /// </summary>
-        [JsonProperty("content")]
-        public string Content { get; set; }
-
-        /// <summary>
-        /// Optional content type / mime type of the source.
-        /// </summary>
-        [JsonProperty("mimeType", NullValueHandling = NullValueHandling.Ignore)]
-        public string MimeType { get; set; }
-    }
-
-    #endregion
-
-    #region LoadedSources Request/Response
-
-    /// <summary>
-    /// Response body for 'loadedSources' request.
-    /// </summary>
-    public class LoadedSourcesResponseBody
-    {
-        [JsonProperty("sources")]
-        public List<Source> Sources { get; set; } = new List<Source>();
-    }
-
-    /// <summary>
-    /// Body for 'loadedSource' event.
-    /// </summary>
-    public class LoadedSourceEventBody
-    {
-        /// <summary>
-        /// "new" | "changed" | "removed"
-        /// </summary>
-        [JsonProperty("reason")]
-        public string Reason { get; set; }
-
-        [JsonProperty("source")]
-        public Source Source { get; set; }
-    }
-
-    #endregion
-
-    #region SetBreakpoints Request/Response
-
-    /// <summary>
-    /// Arguments for 'setBreakpoints' request.
-    /// </summary>
-    public class SetBreakpointsArguments
-    {
-        [JsonProperty("source", NullValueHandling = NullValueHandling.Ignore)]
-        public Source Source { get; set; }
-
-        [JsonProperty("breakpoints")]
-        public List<SourceBreakpoint> Breakpoints { get; set; } = new List<SourceBreakpoint>();
-    }
-
-    /// <summary>
-    /// Properties of a breakpoint passed to the setBreakpoints request.
-    /// </summary>
-    public class SourceBreakpoint
-    {
-        [JsonProperty("line")]
-        public int Line { get; set; }
-
-        [JsonProperty("condition", NullValueHandling = NullValueHandling.Ignore)]
-        public string Condition { get; set; }
-
-        [JsonProperty("logMessage", NullValueHandling = NullValueHandling.Ignore)]
-        public string LogMessage { get; set; }
-    }
-
-    /// <summary>
-    /// Response body for 'setBreakpoints' request.
-    /// </summary>
-    public class SetBreakpointsResponseBody
-    {
-        [JsonProperty("breakpoints")]
-        public List<Breakpoint> Breakpoints { get; set; } = new List<Breakpoint>();
-    }
-
-    /// <summary>
-    /// Information about a breakpoint created in setBreakpoints.
-    /// </summary>
-    public class Breakpoint
-    {
-        [JsonProperty("verified")]
-        public bool Verified { get; set; }
-
-        [JsonProperty("line", NullValueHandling = NullValueHandling.Ignore)]
-        public int? Line { get; set; }
-
-        [JsonProperty("source", NullValueHandling = NullValueHandling.Ignore)]
-        public Source Source { get; set; }
-
-        [JsonProperty("message", NullValueHandling = NullValueHandling.Ignore)]
-        public string Message { get; set; }
-    }
-
-    #endregion
-
     #region Scopes Request/Response
 
     /// <summary>

src/Runner.Worker/Dap/IDapDebugger.cs

@@ -1,5 +1,4 @@
-using System.Collections.Generic;
-using System.Threading.Tasks;
+using System.Threading.Tasks;
 using GitHub.Runner.Common;
 
 namespace GitHub.Runner.Worker.Dap
@@ -22,23 +21,6 @@ namespace GitHub.Runner.Worker.Dap
         Task WaitUntilReadyAsync();
         Task OnStepStartingAsync(IStep step);
         void OnStepCompleted(IStep step);
-
-        /// <summary>
-        /// Called after JobExtension.InitializeJob has returned and the initial
-        /// step queue + post-step stack have been populated. The debugger uses
-        /// these snapshots to build the synthesized job execution view served
-        /// via the DAP source request.
-        /// </summary>
-        Task OnJobStepsInitializedAsync(IEnumerable<IStep> mainQueue, IEnumerable<IStep> initialPostStack);
-
-        /// <summary>
-        /// Called from ExecutionContext.RegisterPostJobStep after a post-step
-        /// is pushed onto the post-job stack. The debugger appends the step
-        /// to the running execution view so the rendered YAML reflects the
-        /// newly-known post-step.
-        /// </summary>
-        void OnPostStepRegistered(IStep step);
-
         Task OnJobCompletedAsync();
         Task StopAsync();
     }

src/Runner.Worker/Dap/JobExecutionView.cs

@@ -1,299 +0,0 @@
-using System;
-using System.Collections.Generic;
-using GitHub.Runner.Sdk;
-
-namespace GitHub.Runner.Worker.Dap
-{
-    /// <summary>
-    /// Stateful, append-only container that wraps <see cref="JobExecutionViewRenderer"/>
-    /// for runtime use. Maintains a mutable list of entries, caches the rendered YAML,
-    /// and provides O(1) lookup from <see cref="IStep"/> identity to the current line
-    /// in the rendered YAML where that step's <c>- step:</c> key appears.
-    ///
-    /// Append-only growth model: post-steps are discovered lazily during execution
-    /// and appended. Setup/pre/main entry line numbers are stable across appends —
-    /// only the synthetic Cleanup boundary (which is not tracked here) shifts.
-    /// </summary>
-    internal sealed class JobExecutionView
-    {
-        private readonly object _lock = new();
-        private readonly string _jobId;
-        private readonly List<JobExecutionViewEntry> _entries = new();
-        private readonly List<IStep> _stepIdentities = new();
-        private readonly Dictionary<IStep, int> _lineByStep =
-            new(ReferenceEqualityComparer.Instance);
-        // Map matchKey -> entry index for placeholders awaiting a future
-        // TryClaim. Removed when claimed.
-        private readonly Dictionary<string, int> _unclaimedByKey =
-            new(StringComparer.Ordinal);
-        private string _yaml;
-        private IReadOnlyList<int> _entryStartLines = Array.Empty<int>();
-
-        public JobExecutionView(string jobId)
-        {
-            if (string.IsNullOrWhiteSpace(jobId))
-            {
-                throw new ArgumentException("jobId must not be null or whitespace.", nameof(jobId));
-            }
-
-            _jobId = jobId;
-            Render();
-        }
-
-        public string JobId
-        {
-            get { return _jobId; }
-        }
-
-        /// <summary>
-        /// Currently rendered YAML. Always reflects all entries appended so far,
-        /// plus the synthetic Setup header and Cleanup footer emitted by the renderer.
-        /// </summary>
-        public string Yaml
-        {
-            get
-            {
-                lock (_lock)
-                {
-                    return _yaml;
-                }
-            }
-        }
-
-        /// <summary>Number of entries (excludes synthetic Setup/Cleanup boundaries).</summary>
-        public int EntryCount
-        {
-            get
-            {
-                lock (_lock)
-                {
-                    return _entries.Count;
-                }
-            }
-        }
-
-        /// <summary>
-        /// 1-based line where entry <paramref name="entryIndex"/>'s <c>- step:</c> key
-        /// currently appears in <see cref="Yaml"/>.
-        /// </summary>
-        public int GetLine(int entryIndex)
-        {
-            lock (_lock)
-            {
-                if (entryIndex < 0 || entryIndex >= _entries.Count)
-                {
-                    throw new ArgumentOutOfRangeException(nameof(entryIndex));
-                }
-
-                return _entryStartLines[entryIndex];
-            }
-        }
-
-        /// <summary>
-        /// 1-based line for the entry whose <see cref="IStep"/> reference identity
-        /// matches <paramref name="step"/>. Returns null if <paramref name="step"/>
-        /// is null or has not been registered.
-        /// </summary>
-        public int? TryGetLineForStep(IStep step)
-        {
-            if (step == null)
-            {
-                return null;
-            }
-
-            lock (_lock)
-            {
-                if (_lineByStep.TryGetValue(step, out var line))
-                {
-                    return line;
-                }
-
-                return null;
-            }
-        }
-
-        /// <summary>
-        /// Append a new entry. If <paramref name="stepIdentity"/> is non-null,
-        /// registers the IStep -> line mapping for later lookup. If
-        /// <paramref name="matchKey"/> is non-null, the entry is registered
-        /// as an unclaimed placeholder that a future
-        /// <see cref="TryClaim(string, IStep)"/> call can bind to a real
-        /// IStep (used by the predictive Post-step path). Re-renders the
-        /// YAML and updates the start-line table.
-        /// </summary>
-        /// <returns>1-based line number of the newly-appended entry's <c>- step:</c> key.</returns>
-        public int Append(JobExecutionViewEntry entry, IStep stepIdentity = null, string matchKey = null)
-        {
-            if (entry == null)
-            {
-                throw new ArgumentNullException(nameof(entry));
-            }
-
-            lock (_lock)
-            {
-                if (stepIdentity != null && _lineByStep.ContainsKey(stepIdentity))
-                {
-                    throw new InvalidOperationException("step already registered in execution view");
-                }
-                if (matchKey != null && _unclaimedByKey.ContainsKey(matchKey))
-                {
-                    throw new InvalidOperationException($"matchKey already registered: {matchKey}");
-                }
-
-                _entries.Add(entry);
-                _stepIdentities.Add(stepIdentity);
-                Render();
-
-                int index = _entries.Count - 1;
-                if (matchKey != null)
-                {
-                    _unclaimedByKey[matchKey] = index;
-                }
-                return _entryStartLines[index];
-            }
-        }
-
-        /// <summary>
-        /// Bind a previously-appended placeholder entry (registered via
-        /// <see cref="Append(JobExecutionViewEntry, IStep, string)"/> with
-        /// a non-null <c>matchKey</c>) to a real <see cref="IStep"/>.
-        /// Returns the 1-based line of the now-claimed entry on success.
-        /// Returns null when no unclaimed placeholder exists for
-        /// <paramref name="matchKey"/>, OR when <paramref name="stepIdentity"/>
-        /// is already registered for a different entry (defensive).
-        /// Does not re-render: claim only updates the IStep -> line index.
-        /// </summary>
-        public int? TryClaim(string matchKey, IStep stepIdentity)
-        {
-            if (matchKey == null)
-            {
-                throw new ArgumentNullException(nameof(matchKey));
-            }
-            if (stepIdentity == null)
-            {
-                throw new ArgumentNullException(nameof(stepIdentity));
-            }
-
-            lock (_lock)
-            {
-                if (!_unclaimedByKey.TryGetValue(matchKey, out int index))
-                {
-                    return null;
-                }
-                if (_lineByStep.ContainsKey(stepIdentity))
-                {
-                    // Bail rather than double-register the step.
-                    return null;
-                }
-
-                _unclaimedByKey.Remove(matchKey);
-                _stepIdentities[index] = stepIdentity;
-                _lineByStep[stepIdentity] = _entryStartLines[index];
-                return _entryStartLines[index];
-            }
-        }
-
-        /// <summary>
-        /// Mark a previously-appended unclaimed placeholder as skipped. Used
-        /// when the predicting Main step never runs (skipped by <c>if:</c>),
-        /// so its predicted Post-step placeholder should not appear as a
-        /// step that will execute. Re-renders the view (inline comment only
-        /// — subsequent entry line numbers stay stable).
-        /// </summary>
-        /// <returns>
-        /// true if a matching unclaimed placeholder was marked; false when
-        /// no placeholder exists for <paramref name="matchKey"/>, or the
-        /// placeholder has already been claimed (claim wins).
-        /// </returns>
-        public bool TryMarkSkipped(string matchKey)
-        {
-            ArgUtil.NotNull(matchKey, nameof(matchKey));
-
-            lock (_lock)
-            {
-                if (!_unclaimedByKey.TryGetValue(matchKey, out int index))
-                {
-                    return false;
-                }
-                // Defensive: only mark if it's still an unclaimed placeholder.
-                if (_stepIdentities[index] != null)
-                {
-                    return false;
-                }
-
-                if (_entries[index].IsSkipped)
-                {
-                    // Idempotent — already marked.
-                    return true;
-                }
-                _entries[index].IsSkipped = true;
-                _unclaimedByKey.Remove(matchKey);
-                Render();
-                return true;
-            }
-        }
-
-        /// <summary>
-        /// Bulk-append for the initial population. Equivalent to calling
-        /// <see cref="Append"/> once per pair, but renders only once at the end.
-        /// State is left unchanged if any input is invalid.
-        /// </summary>
-        public void AppendRange(IEnumerable<(JobExecutionViewEntry entry, IStep stepIdentity)> items)
-        {
-            ArgUtil.NotNull(items, nameof(items));
-
-            // Materialize first so we don't enumerate twice.
-            var materialized = new List<(JobExecutionViewEntry entry, IStep stepIdentity)>(items);
-            for (int i = 0; i < materialized.Count; i++)
-            {
-                if (materialized[i].entry == null)
-                {
-                    throw new ArgumentException($"items[{i}].entry is null.", nameof(items));
-                }
-            }
-
-            lock (_lock)
-            {
-                // Validate no duplicates within the input or with existing identities,
-                // before mutating state.
-                var seen = new HashSet<IStep>(ReferenceEqualityComparer.Instance);
-                foreach (var (_, stepIdentity) in materialized)
-                {
-                    if (stepIdentity == null)
-                    {
-                        continue;
-                    }
-                    if (_lineByStep.ContainsKey(stepIdentity) || !seen.Add(stepIdentity))
-                    {
-                        throw new InvalidOperationException("step already registered in execution view");
-                    }
-                }
-
-                foreach (var (entry, stepIdentity) in materialized)
-                {
-                    _entries.Add(entry);
-                    _stepIdentities.Add(stepIdentity);
-                }
-                Render();
-            }
-        }
-
-        // Caller MUST hold _lock (constructor's call is safe — no concurrent access yet).
-        private void Render()
-        {
-            var result = JobExecutionViewRenderer.Render(_jobId, _entries.AsReadOnly());
-            _yaml = result.Yaml;
-            _entryStartLines = result.EntryStartLines;
-
-            _lineByStep.Clear();
-            for (int i = 0; i < _stepIdentities.Count; i++)
-            {
-                var step = _stepIdentities[i];
-                if (step != null)
-                {
-                    _lineByStep[step] = _entryStartLines[i];
-                }
-            }
-        }
-    }
-}

src/Runner.Worker/Dap/JobExecutionViewRenderer.cs

@@ -1,391 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Globalization;
-using System.IO;
-using System.Text;
-using GitHub.Runner.Sdk;
-using YamlDotNet.Core;
-using YamlDotNet.Core.Events;
-
-namespace GitHub.Runner.Worker.Dap
-{
-    /// <summary>
-    /// Phase a step occupies in the runner's flat execution sequence.
-    /// Setup and Cleanup are NOT modeled here — they are synthetic
-    /// boundaries hard-coded by <see cref="JobExecutionViewRenderer"/>
-    /// and cannot be constructed by callers.
-    /// </summary>
-    internal enum JobExecutionPhase
-    {
-        Pre,
-        Main,
-        Post,
-    }
-
-    /// <summary>
-    /// One step in the rendered execution view. Pure data; no link to
-    /// any worker type. Phase 2 will translate runner step objects
-    /// into instances of this record.
-    /// </summary>
-    internal sealed class JobExecutionViewEntry
-    {
-        public JobExecutionViewEntry(
-            JobExecutionPhase phase,
-            string displayName,
-            string uses = null,
-            string run = null,
-            string sourcePath = null,
-            int sourceLine = 0,
-            string id = null,
-            string @if = null,
-            string continueOnError = null,
-            string timeoutMinutes = null,
-            string envYaml = null,
-            string withYaml = null,
-            string shell = null,
-            string workingDirectory = null)
-        {
-            if (string.IsNullOrWhiteSpace(displayName))
-            {
-                throw new ArgumentException("displayName must not be null or whitespace.", nameof(displayName));
-            }
-            if (sourcePath != null && sourceLine < 1)
-            {
-                throw new ArgumentException(
-                    "sourceLine must be >= 1 when sourcePath is provided.",
-                    nameof(sourceLine));
-            }
-
-            Phase = phase;
-            DisplayName = displayName;
-            Uses = uses;
-            Run = run;
-            SourcePath = sourcePath;
-            SourceLine = sourceLine;
-            Id = id;
-            If = @if;
-            ContinueOnError = continueOnError;
-            TimeoutMinutes = timeoutMinutes;
-            EnvYaml = envYaml;
-            WithYaml = withYaml;
-            Shell = shell;
-            WorkingDirectory = workingDirectory;
-        }
-
-        public JobExecutionPhase Phase { get; }
-        public string DisplayName { get; }
-        public string Uses { get; }
-        public string Run { get; }
-        public string SourcePath { get; }
-        public int SourceLine { get; }
-        public string Id { get; }
-        public string If { get; }
-        public string ContinueOnError { get; }
-        public string TimeoutMinutes { get; }
-        // Pre-serialized YAML fragment, already indented for embedding
-        // under the entry's `env:` key (6-space child indent).
-        public string EnvYaml { get; }
-        public string WithYaml { get; }
-        public string Shell { get; }
-        public string WorkingDirectory { get; }
-
-        /// <summary>
-        /// Set when the corresponding step was skipped (e.g. predicted Post
-        /// placeholder for a Main step that never executed because its
-        /// <c>if:</c> evaluated false). Rendered as an inline YAML comment
-        /// on the entry's <c>- step:</c> line so subsequent entry line
-        /// numbers stay stable.
-        /// </summary>
-        public bool IsSkipped { get; internal set; }
-    }
-
-    /// <summary>
-    /// Output of <see cref="JobExecutionViewRenderer.Render"/>: the YAML
-    /// document plus a parallel array of 1-based line numbers, one per
-    /// input entry, where each entry's <c>- step:</c> key appears.
-    /// Synthetic Setup/Cleanup boundaries are not tracked here.
-    /// </summary>
-    internal readonly struct RenderResult
-    {
-        public RenderResult(string yaml, IReadOnlyList<int> entryStartLines)
-        {
-            Yaml = yaml;
-            EntryStartLines = entryStartLines;
-        }
-
-        public string Yaml { get; }
-        public IReadOnlyList<int> EntryStartLines { get; }
-    }
-
-    /// <summary>
-    /// Renders a job's execution-view YAML. Pure function; no I/O,
-    /// no logging, no static state. Output format and Setup/Cleanup
-    /// boundaries are fixed; callers cannot influence them.
-    ///
-    /// Output is structured as phase-keyed top-level sections:
-    /// <c>setup:</c>, <c>pre:</c>, <c>main:</c>, <c>post:</c>, <c>cleanup:</c>.
-    /// <c>setup:</c> and <c>cleanup:</c> always render; <c>pre:</c>,
-    /// <c>main:</c>, <c>post:</c> only render when they contain at least
-    /// one entry.
-    /// </summary>
-    internal static class JobExecutionViewRenderer
-    {
-        public static RenderResult Render(string jobId, IReadOnlyList<JobExecutionViewEntry> entries)
-        {
-            if (string.IsNullOrWhiteSpace(jobId))
-            {
-                throw new ArgumentException("jobId must not be null or whitespace.", nameof(jobId));
-            }
-            ArgUtil.NotNull(entries, nameof(entries));
-
-            // Pre-validate non-null entries before any output, so partial
-            // state is never observed by callers.
-            for (int i = 0; i < entries.Count; i++)
-            {
-                if (entries[i] == null)
-                {
-                    throw new ArgumentException($"entries[{i}] is null.", nameof(entries));
-                }
-            }
-
-            var sb = new StringBuilder();
-            var startLines = new int[entries.Count];
-            int newlinesEmitted = 0;
-
-            // Header (3 lines).
-            sb.Append("# Job: ").Append(FormatScalar(jobId)).Append('\n');
-            sb.Append("# Runner execution plan — read-only.\n");
-            sb.Append('\n');
-            newlinesEmitted += 3;
-
-            // setup: section — always present.
-            sb.Append("setup:\n");
-            sb.Append("  - step: Setup job\n");
-            newlinesEmitted += 2;
-
-            // Render phase sections in fixed order. Each emits a leading
-            // blank line separator before its header.
-            EmitPhaseSection(sb, "pre", JobExecutionPhase.Pre, entries, startLines, ref newlinesEmitted);
-            EmitPhaseSection(sb, "main", JobExecutionPhase.Main, entries, startLines, ref newlinesEmitted);
-            EmitPhaseSection(sb, "post", JobExecutionPhase.Post, entries, startLines, ref newlinesEmitted);
-
-            // cleanup: section — always present, preceded by a blank line.
-            sb.Append('\n');
-            sb.Append("cleanup:\n");
-            sb.Append("  - step: Complete job\n");
-
-            return new RenderResult(sb.ToString(), Array.AsReadOnly(startLines));
-        }
-
-        private static void EmitPhaseSection(
-            StringBuilder sb,
-            string sectionName,
-            JobExecutionPhase phase,
-            IReadOnlyList<JobExecutionViewEntry> entries,
-            int[] startLines,
-            ref int newlinesEmitted)
-        {
-            // Skip the section entirely if no entries belong to this phase.
-            bool any = false;
-            for (int i = 0; i < entries.Count; i++)
-            {
-                if (entries[i].Phase == phase) { any = true; break; }
-            }
-            if (!any)
-            {
-                return;
-            }
-
-            // Blank line separator + section header.
-            sb.Append('\n');
-            sb.Append(sectionName).Append(":\n");
-            newlinesEmitted += 2;
-
-            for (int i = 0; i < entries.Count; i++)
-            {
-                var entry = entries[i];
-                if (entry.Phase != phase)
-                {
-                    continue;
-                }
-
-                // 1-based line of the `- step:` key for this entry.
-                startLines[i] = newlinesEmitted + 1;
-
-                sb.Append("  - step: ").Append(FormatScalar(entry.DisplayName));
-                if (entry.IsSkipped)
-                {
-                    // Inline comment — keeps following entry line numbers stable.
-                    sb.Append("  # (skipped — main step did not execute)");
-                }
-                sb.Append('\n');
-                newlinesEmitted++;
-
-                switch (phase)
-                {
-                    case JobExecutionPhase.Pre:
-                    case JobExecutionPhase.Post:
-                        if (!string.IsNullOrEmpty(entry.Uses))
-                        {
-                            sb.Append("    action: ").Append(FormatScalar(entry.Uses)).Append('\n');
-                            newlinesEmitted++;
-                        }
-                        // No source: annotation for pre/post.
-                        break;
-
-                    case JobExecutionPhase.Main:
-                        if (!string.IsNullOrEmpty(entry.Id))
-                        {
-                            sb.Append("    id: ").Append(FormatScalar(entry.Id)).Append('\n');
-                            newlinesEmitted++;
-                        }
-                        if (!string.IsNullOrEmpty(entry.Uses))
-                        {
-                            sb.Append("    uses: ").Append(FormatScalar(entry.Uses)).Append('\n');
-                            newlinesEmitted++;
-                        }
-                        if (!string.IsNullOrEmpty(entry.Run))
-                        {
-                            if (entry.Run.IndexOf('\n') < 0)
-                            {
-                                sb.Append("    run: ").Append(FormatScalar(entry.Run)).Append('\n');
-                                newlinesEmitted++;
-                            }
-                            else
-                            {
-                                sb.Append("    run: |\n");
-                                newlinesEmitted++;
-                                newlinesEmitted += AppendIndentedBlock(sb, entry.Run, "      ");
-                            }
-                        }
-                        if (!string.IsNullOrEmpty(entry.If))
-                        {
-                            sb.Append("    if: ").Append(FormatScalar(entry.If)).Append('\n');
-                            newlinesEmitted++;
-                        }
-                        if (!string.IsNullOrEmpty(entry.ContinueOnError))
-                        {
-                            sb.Append("    continue-on-error: ").Append(entry.ContinueOnError).Append('\n');
-                            newlinesEmitted++;
-                        }
-                        if (!string.IsNullOrEmpty(entry.TimeoutMinutes))
-                        {
-                            sb.Append("    timeout-minutes: ").Append(entry.TimeoutMinutes).Append('\n');
-                            newlinesEmitted++;
-                        }
-                        if (!string.IsNullOrEmpty(entry.EnvYaml))
-                        {
-                            sb.Append("    env:\n");
-                            newlinesEmitted++;
-                            sb.Append(entry.EnvYaml).Append('\n');
-                            newlinesEmitted += CountChar(entry.EnvYaml, '\n') + 1;
-                        }
-                        if (!string.IsNullOrEmpty(entry.WithYaml))
-                        {
-                            sb.Append("    with:\n");
-                            newlinesEmitted++;
-                            sb.Append(entry.WithYaml).Append('\n');
-                            newlinesEmitted += CountChar(entry.WithYaml, '\n') + 1;
-                        }
-                        if (!string.IsNullOrEmpty(entry.Shell))
-                        {
-                            sb.Append("    shell: ").Append(FormatScalar(entry.Shell)).Append('\n');
-                            newlinesEmitted++;
-                        }
-                        if (!string.IsNullOrEmpty(entry.WorkingDirectory))
-                        {
-                            sb.Append("    working-directory: ").Append(FormatScalar(entry.WorkingDirectory)).Append('\n');
-                            newlinesEmitted++;
-                        }
-                        if (entry.SourcePath != null)
-                        {
-                            sb.Append("    source: ")
-                              .Append(entry.SourcePath)
-                              .Append(':')
-                              .Append(entry.SourceLine.ToString(CultureInfo.InvariantCulture))
-                              .Append('\n');
-                            newlinesEmitted++;
-                        }
-                        break;
-                }
-            }
-        }
-
-        private static int AppendIndentedBlock(StringBuilder sb, string text, string indent)
-        {
-            int newlines = 0;
-            int i = 0;
-            while (i < text.Length)
-            {
-                int end = text.IndexOf('\n', i);
-                int lineEnd = end < 0 ? text.Length : end;
-                int trimEnd = lineEnd;
-                if (trimEnd > i && text[trimEnd - 1] == '\r')
-                {
-                    trimEnd--;
-                }
-                if (trimEnd > i)
-                {
-                    sb.Append(indent);
-                    sb.Append(text, i, trimEnd - i);
-                }
-                sb.Append('\n');
-                newlines++;
-                if (end < 0)
-                {
-                    break;
-                }
-                i = end + 1;
-            }
-            return newlines;
-        }
-
-        private static int CountChar(string s, char c)
-        {
-            int n = 0;
-            for (int i = 0; i < s.Length; i++)
-            {
-                if (s[i] == c) n++;
-            }
-            return n;
-        }
-
-        /// <summary>
-        /// Formats a single string as a YAML 1.x flow scalar, delegating
-        /// quoting/escaping decisions to YamlDotNet. This avoids maintaining
-        /// our own escape table for every YAML-significant character: we
-        /// just emit the value through the YAML library and use whichever
-        /// scalar style (plain, single-quoted, double-quoted) it picks.
-        /// A new <see cref="Emitter"/> is created per call, so the helper
-        /// is safe to invoke concurrently.
-        /// </summary>
-        internal static string FormatScalar(string value)
-        {
-            if (value == null)
-            {
-                throw new ArgumentNullException(nameof(value));
-            }
-
-            using var sw = new StringWriter(CultureInfo.InvariantCulture);
-            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();
-            if (raw.StartsWith("--- ", 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.TrimEnd('\n');
-        }
-    }
-}

src/Runner.Worker/Dap/StepEntryTranslator.cs

@@ -1,238 +0,0 @@
-using System;
-using System.Collections.Generic;
-using GitHub.DistributedTask.ObjectTemplating.Tokens;
-using GitHub.DistributedTask.Pipelines;
-using GitHub.Runner.Sdk;
-
-namespace GitHub.Runner.Worker.Dap
-{
-    /// <summary>
-    /// Translates runner <see cref="IStep"/> instances into pure-data
-    /// <see cref="JobExecutionViewEntry"/> records used by the DAP debugger
-    /// execution view. Filters out runner-internal steps (e.g.
-    /// <see cref="JobExtensionRunner"/>) so the rendered view only shows
-    /// user-visible workflow steps.
-    /// </summary>
-    internal static class StepEntryTranslator
-    {
-        // Run-step internals carried on ActionStep.Inputs that are NOT
-        // user-authored `with:` entries.
-        private static readonly HashSet<string> RunStepInternalKeys = new(StringComparer.Ordinal)
-        {
-            "script",
-            "shell",
-            "working-directory",
-        };
-
-        /// <summary>
-        /// Translate an IStep into a JobExecutionViewEntry.
-        /// </summary>
-        /// <param name="step">The IStep to translate. Must not be null.</param>
-        /// <returns>
-        /// A JobExecutionViewEntry, or null if the step is not user-visible
-        /// (JobExtensionRunner and any other non-IActionRunner IStep impls).
-        /// </returns>
-        public static JobExecutionViewEntry TryTranslate(IStep step)
-        {
-            ArgUtil.NotNull(step, nameof(step));
-
-            if (step is JobExtensionRunner)
-            {
-                return null;
-            }
-
-            if (step is not IActionRunner actionRunner)
-            {
-                return null;
-            }
-
-            var phase = actionRunner.Stage switch
-            {
-                ActionRunStage.Pre => JobExecutionPhase.Pre,
-                ActionRunStage.Post => JobExecutionPhase.Post,
-                _ => JobExecutionPhase.Main,
-            };
-
-            string displayName = actionRunner.DisplayName;
-            if (string.IsNullOrWhiteSpace(displayName))
-            {
-                displayName = "run";
-            }
-
-            string uses = null;
-            string run = null;
-            string id = null;
-            string ifCond = null;
-            string continueOnError = null;
-            string timeoutMinutes = null;
-            string envYaml = null;
-            string withYaml = null;
-            string shell = null;
-            string workingDirectory = null;
-
-            var action = actionRunner.Action;
-            var reference = action?.Reference;
-            bool isScript = reference?.Type == ActionSourceType.Script;
-
-            if (reference != null && !isScript)
-            {
-                uses = FormatActionReference(reference);
-            }
-
-            // Only the user-visible Main entry surfaces authored params.
-            // Pre/Post stay minimal (step + action) — they reference the
-            // same Action as the Main entry, and duplicating params adds
-            // noise without information.
-            if (phase == JobExecutionPhase.Main && action != null)
-            {
-                id = FilterAuthoredId(action.ContextName);
-
-                if (!string.IsNullOrEmpty(action.Condition))
-                {
-                    ifCond = action.Condition;
-                }
-
-                if (action.ContinueOnError != null)
-                {
-                    continueOnError = TemplateTokenYamlAdapter.Serialize(action.ContinueOnError, indentSpaces: 0);
-                }
-                if (action.TimeoutInMinutes != null)
-                {
-                    timeoutMinutes = TemplateTokenYamlAdapter.Serialize(action.TimeoutInMinutes, indentSpaces: 0);
-                }
-
-                if (action.Environment is MappingToken envMap && envMap.Count > 0)
-                {
-                    envYaml = TemplateTokenYamlAdapter.Serialize(envMap, indentSpaces: 6);
-                }
-                else if (action.Environment != null && !(action.Environment is MappingToken))
-                {
-                    // Unusual but possible: env: ${{ ... }} expression form.
-                    envYaml = TemplateTokenYamlAdapter.Serialize(action.Environment, indentSpaces: 6);
-                }
-
-                if (isScript)
-                {
-                    var inputs = action.Inputs as MappingToken;
-                    if (inputs != null)
-                    {
-                        if (TryGetMapValue(inputs, "script", out var scriptTok) && scriptTok != null)
-                        {
-                            run = scriptTok.ToString();
-                        }
-                        if (TryGetMapValue(inputs, "shell", out var shellTok) && shellTok != null)
-                        {
-                            string shellText = shellTok.ToString();
-                            if (!string.IsNullOrEmpty(shellText))
-                            {
-                                shell = shellText;
-                            }
-                        }
-                        if (TryGetMapValue(inputs, "working-directory", out var wdTok) && wdTok != null)
-                        {
-                            string wdText = wdTok.ToString();
-                            if (!string.IsNullOrEmpty(wdText))
-                            {
-                                workingDirectory = wdText;
-                            }
-                        }
-                    }
-                }
-                else
-                {
-                    // Action step: surface `with:` entries, filtering any
-                    // run-step internal keys defensively.
-                    if (action.Inputs is MappingToken withMap && withMap.Count > 0)
-                    {
-                        var filtered = FilterMapping(withMap, RunStepInternalKeys);
-                        if (filtered != null && filtered.Count > 0)
-                        {
-                            withYaml = TemplateTokenYamlAdapter.Serialize(filtered, indentSpaces: 6);
-                        }
-                    }
-                }
-            }
-
-            // Source annotation (SourcePath/SourceLine) requires a public
-            // seam onto TemplateToken position info — not wired yet.
-            return new JobExecutionViewEntry(
-                phase: phase,
-                displayName: displayName,
-                uses: uses,
-                run: run,
-                sourcePath: null,
-                sourceLine: 0,
-                id: id,
-                @if: ifCond,
-                continueOnError: continueOnError,
-                timeoutMinutes: timeoutMinutes,
-                envYaml: envYaml,
-                withYaml: withYaml,
-                shell: shell,
-                workingDirectory: workingDirectory);
-        }
-
-        /// <summary>
-        /// Auto-generated step IDs are noise in the view: filter them out.
-        /// The runner's convention (see ExecutionContext) is that auto-
-        /// generated context names start with <c>__</c>. Only user-authored
-        /// IDs survive the filter.
-        /// </summary>
-        internal static string FilterAuthoredId(string contextName)
-        {
-            if (string.IsNullOrWhiteSpace(contextName))
-            {
-                return null;
-            }
-            if (contextName.StartsWith("__", StringComparison.Ordinal))
-            {
-                return null;
-            }
-            return contextName;
-        }
-
-        private static bool TryGetMapValue(MappingToken map, string key, out TemplateToken value)
-        {
-            foreach (var pair in map)
-            {
-                if (pair.Key is StringToken s && string.Equals(s.Value, key, StringComparison.Ordinal))
-                {
-                    value = pair.Value;
-                    return true;
-                }
-            }
-            value = null;
-            return false;
-        }
-
-        private static MappingToken FilterMapping(MappingToken source, HashSet<string> excludeKeys)
-        {
-            var copy = new MappingToken(source.FileId, source.Line, source.Column);
-            foreach (var pair in source)
-            {
-                if (pair.Key is StringToken sk && excludeKeys.Contains(sk.Value))
-                {
-                    continue;
-                }
-                copy.Add(pair);
-            }
-            return copy;
-        }
-
-        internal static string FormatActionReference(ActionStepDefinitionReference reference)
-        {
-            switch (reference)
-            {
-                case RepositoryPathReference repo:
-                    var path = string.IsNullOrEmpty(repo.Path) ? string.Empty : $"/{repo.Path}";
-                    return string.IsNullOrEmpty(repo.Ref)
-                        ? $"{repo.Name}{path}"
-                        : $"{repo.Name}{path}@{repo.Ref}";
-                case ContainerRegistryReference container:
-                    return container.Image;
-                default:
-                    return reference.ToString();
-            }
-        }
-    }
-}

src/Runner.Worker/Dap/TemplateTokenYamlAdapter.cs

@@ -1,148 +0,0 @@
-using System;
-using System.Globalization;
-using System.IO;
-using GitHub.DistributedTask.ObjectTemplating;
-using GitHub.DistributedTask.ObjectTemplating.Tokens;
-using GitHub.Runner.Sdk;
-using YamlDotNet.Core;
-using YamlDotNet.Core.Events;
-
-namespace GitHub.Runner.Worker.Dap
-{
-    /// <summary>
-    /// Adapts a YamlDotNet <see cref="IEmitter"/> as a DT
-    /// <see cref="IObjectWriter"/> so a <see cref="TemplateToken"/> DOM
-    /// can be serialized back to YAML preserving its pre-evaluation form
-    /// (basic <c>${{ }}</c> expressions are written through verbatim).
-    ///
-    /// Used by the DAP execution view to surface user-authored step
-    /// parameters (<c>env:</c>, <c>with:</c>, <c>run:</c>, ...) without
-    /// any expression substitution.
-    /// </summary>
-    internal sealed class TemplateTokenYamlAdapter : IObjectWriter
-    {
-        private readonly IEmitter _emitter;
-
-        public TemplateTokenYamlAdapter(IEmitter emitter)
-        {
-            ArgUtil.NotNull(emitter, nameof(emitter));
-            _emitter = emitter;
-        }
-
-        public void WriteStart()
-        {
-            _emitter.Emit(new StreamStart());
-            _emitter.Emit(new DocumentStart(null, null, true));
-        }
-
-        public void WriteEnd()
-        {
-            _emitter.Emit(new DocumentEnd(true));
-            _emitter.Emit(new StreamEnd());
-        }
-
-        public void WriteNull() =>
-            _emitter.Emit(new Scalar(null, null, "null", ScalarStyle.Plain, true, false));
-
-        public void WriteBoolean(bool value) =>
-            _emitter.Emit(new Scalar(null, null, value ? "true" : "false", ScalarStyle.Plain, true, false));
-
-        public void WriteNumber(double value) =>
-            _emitter.Emit(new Scalar(null, null, value.ToString("R", CultureInfo.InvariantCulture), ScalarStyle.Plain, true, false));
-
-        public void WriteString(string value)
-        {
-            if (value == null)
-            {
-                WriteNull();
-                return;
-            }
-            // Multi-line strings render as block literal so embedded
-            // newlines survive the YAML round trip.
-            var style = value.IndexOf('\n') >= 0 ? ScalarStyle.Literal : ScalarStyle.Any;
-            _emitter.Emit(new Scalar(null, null, value, style, true, true));
-        }
-
-        public void WriteSequenceStart() =>
-            _emitter.Emit(new SequenceStart(null, null, true, SequenceStyle.Any));
-
-        public void WriteSequenceEnd() =>
-            _emitter.Emit(new SequenceEnd());
-
-        public void WriteMappingStart() =>
-            _emitter.Emit(new MappingStart(null, null, true, MappingStyle.Any));
-
-        public void WriteMappingEnd() =>
-            _emitter.Emit(new MappingEnd());
-
-        /// <summary>
-        /// Serialize a TemplateToken to a YAML fragment ready to embed
-        /// under a parent key. Each non-empty line is prefixed by
-        /// <paramref name="indentSpaces"/> spaces. Trailing newlines and
-        /// the YAML stream start/document markers are stripped, so the
-        /// caller controls line breaks.
-        /// </summary>
-        /// <remarks>
-        /// Empty mappings render as <c>{}</c> and empty sequences as
-        /// <c>[]</c> via YamlDotNet's flow style fallback for empty
-        /// collections.
-        /// </remarks>
-        internal static string Serialize(TemplateToken token, int indentSpaces)
-        {
-            if (indentSpaces < 0)
-            {
-                throw new ArgumentOutOfRangeException(nameof(indentSpaces));
-            }
-
-            using var sw = new StringWriter(CultureInfo.InvariantCulture);
-            var emitter = new Emitter(sw);
-            var adapter = new TemplateTokenYamlAdapter(emitter);
-            TemplateWriter.Write(adapter, token);
-
-            string raw = sw.ToString();
-            // Strip YAML document markers ("--- " prefix and "\n..." suffix).
-            if (raw.StartsWith("--- ", StringComparison.Ordinal))
-            {
-                raw = raw.Substring(4);
-            }
-            const string DocEndMarker = "\n...";
-            if (raw.EndsWith(DocEndMarker + "\n", StringComparison.Ordinal))
-            {
-                raw = raw.Substring(0, raw.Length - DocEndMarker.Length - 1);
-            }
-            else if (raw.EndsWith(DocEndMarker, StringComparison.Ordinal))
-            {
-                raw = raw.Substring(0, raw.Length - DocEndMarker.Length);
-            }
-            raw = raw.TrimEnd('\n');
-
-            if (indentSpaces == 0)
-            {
-                return raw;
-            }
-
-            // Re-indent every non-empty line. Empty lines remain empty
-            // so YAML block-literal blank lines stay valid.
-            var pad = new string(' ', indentSpaces);
-            var sb = new System.Text.StringBuilder(raw.Length + indentSpaces * 4);
-            int i = 0;
-            while (i < raw.Length)
-            {
-                int end = raw.IndexOf('\n', i);
-                int lineEnd = end < 0 ? raw.Length : end;
-                if (lineEnd > i)
-                {
-                    sb.Append(pad);
-                    sb.Append(raw, i, lineEnd - i);
-                }
-                if (end < 0)
-                {
-                    break;
-                }
-                sb.Append('\n');
-                i = end + 1;
-            }
-            return sb.ToString();
-        }
-    }
-}

src/Runner.Worker/ExecutionContext.cs

@@ -338,14 +338,6 @@ namespace GitHub.Runner.Worker
 
             step.ExecutionContext = Root.CreatePostChild(step.DisplayName, IntraActionState, siblingScopeName);
             Root.PostJobSteps.Push(step);
-            // Only consult the DAP debugger when it was actually enabled for this job.
-            // Without this guard, HostContext.GetService<IDapDebugger>() would auto-
-            // instantiate the default singleton for every non-debug job, violating the
-            // "no debugger, no risk" containment property.
-            if (Global.Debugger?.Enabled == true)
-            {
-                HostContext.GetService<Dap.IDapDebugger>().OnPostStepRegistered(step);
-            }
         }
 
         public IExecutionContext CreateChild(

src/Runner.Worker/JobRunner.cs

@@ -230,24 +230,6 @@ namespace GitHub.Runner.Worker
                         jobContext.JobSteps.Enqueue(step);
                     }
 
-                    if (jobContext.Global.Debugger?.Enabled == true)
-                    {
-                        // Only consult the DAP debugger when it was actually enabled for this job.
-                        // Without this guard, HostContext.GetService<IDapDebugger>() would auto-
-                        // instantiate the default singleton for every non-debug job, violating the
-                        // "no debugger, no risk" containment property.
-                        var dapDebugger = HostContext.GetService<Dap.IDapDebugger>();
-                        try
-                        {
-                            await dapDebugger.OnJobStepsInitializedAsync(jobContext.JobSteps, jobContext.PostJobSteps);
-                        }
-                        catch (Exception ex)
-                        {
-                            Trace.Warning("DAP OnJobStepsInitialized error; continuing without DAP view.");
-                            Trace.Error(ex);
-                        }
-                    }
-
                     await stepsRunner.RunAsync(jobContext);
                 }
                 catch (Exception ex)

src/Runner.Worker/StepsRunner.cs

@@ -219,18 +219,12 @@ namespace GitHub.Runner.Worker
                             // Condition is false
                             Trace.Info("Skipping step due to condition evaluation.");
                             CompleteStep(step, TaskResult.Skipped, resultCode: conditionTraceWriter.Trace);
-                            // Notify the DAP debugger so any predicted Post-step
-                            // placeholder for this Main step can be marked as
-                            // skipped — otherwise the rendered view leaves a
-                            // stale "Post X" entry for a step that never ran.
-                            dapDebugger?.OnStepCompleted(step);
                         }
                         else if (conditionEvaluateError != null)
                         {
                             // Condition error
                             step.ExecutionContext.Error(conditionEvaluateError);
                             CompleteStep(step, TaskResult.Failed);
-                            dapDebugger?.OnStepCompleted(step);
                         }
                         else
                         {

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/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;
@@ -867,574 +867,5 @@ namespace GitHub.Runner.Common.Tests.Worker
                 Assert.Equal(completedTask, finished);
             }
         }
-
-        // ---------------------------------------------------------------------
-        // Phase 2c: synthesized execution view as DAP source.
-        // ---------------------------------------------------------------------
-
-        private static Mock<GitHub.Runner.Worker.IActionRunner> NewActionRunner(
-            GitHub.Runner.Worker.ActionRunStage stage,
-            string displayName,
-            string actionName = "actions/checkout",
-            string actionRef = "v4")
-        {
-            var mock = new Mock<GitHub.Runner.Worker.IActionRunner>();
-            mock.SetupGet(x => x.Stage).Returns(stage);
-            mock.SetupGet(x => x.DisplayName).Returns(displayName);
-            mock.SetupGet(x => x.Action).Returns(new GitHub.DistributedTask.Pipelines.ActionStep
-            {
-                Reference = new GitHub.DistributedTask.Pipelines.RepositoryPathReference
-                {
-                    Name = actionName,
-                    Ref = actionRef,
-                },
-            });
-            return mock;
-        }
-
-        private async Task DriveDebuggerToReadyAsync(int port)
-        {
-            var waitTask = _debugger.WaitUntilReadyAsync();
-            var client = new TcpClient();
-            await client.ConnectAsync(IPAddress.Loopback, port);
-            var stream = client.GetStream();
-            await SendRequestAsync(stream, new Request
-            {
-                Seq = 1,
-                Type = "request",
-                Command = "configurationDone",
-            });
-            await waitTask;
-            // Hold the client alive via GC root in caller scope through field.
-            _liveDriveClient = client;
-        }
-
-        private TcpClient _liveDriveClient;
-
-        private static Request MakeRequest(string command, object args = null)
-        {
-            return new Request
-            {
-                Seq = 1,
-                Type = "request",
-                Command = command,
-                Arguments = args == null ? null : Newtonsoft.Json.Linq.JObject.FromObject(args),
-            };
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task HandleSource_ReturnsExecutionViewYaml()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port, "ci-job");
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveDebuggerToReadyAsync(port);
-                    var step = NewActionRunner(GitHub.Runner.Worker.ActionRunStage.Main, "Run").Object;
-                    await _debugger.OnJobStepsInitializedAsync(new[] { step }, Array.Empty<IStep>());
-
-                    var response = _debugger.HandleSource(MakeRequest("source", new SourceArguments { SourceReference = 1 }));
-                    Assert.True(response.Success);
-                    var body = Assert.IsType<SourceResponseBody>(response.Body);
-                    Assert.Equal(_debugger.ExecutionView.Yaml, body.Content);
-                    Assert.Null(body.MimeType);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task HandleSource_UnknownReference_Fails()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port, "ci-job");
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveDebuggerToReadyAsync(port);
-                    var step = NewActionRunner(GitHub.Runner.Worker.ActionRunStage.Main, "Run").Object;
-                    await _debugger.OnJobStepsInitializedAsync(new[] { step }, Array.Empty<IStep>());
-
-                    var response = _debugger.HandleSource(MakeRequest("source", new SourceArguments { SourceReference = 999 }));
-                    Assert.False(response.Success);
-                    Assert.Contains("Unknown source reference", response.Message);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task HandleSource_NoView_Fails()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port, "ci-job");
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveDebuggerToReadyAsync(port);
-                    // No OnJobStepsInitializedAsync call — view is null.
-                    var response = _debugger.HandleSource(MakeRequest("source", new SourceArguments { SourceReference = 1 }));
-                    Assert.False(response.Success);
-                    Assert.Contains("Execution view not yet available", response.Message);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task HandleSource_OmitsMimeType()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port, "ci-job");
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveDebuggerToReadyAsync(port);
-                    var step = NewActionRunner(GitHub.Runner.Worker.ActionRunStage.Main, "Run").Object;
-                    await _debugger.OnJobStepsInitializedAsync(new[] { step }, Array.Empty<IStep>());
-
-                    var response = _debugger.HandleSource(MakeRequest("source", new SourceArguments { SourceReference = 1 }));
-                    Assert.True(response.Success);
-                    var body = Assert.IsType<SourceResponseBody>(response.Body);
-                    // MimeType is intentionally omitted so DAP clients fall through
-                    // to path-extension detection (`.yml`) — the most consistently
-                    // honored mechanism across VS Code, nvim-dap, and JetBrains.
-                    Assert.Null(body.MimeType);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task HandleSource_MasksSecrets()
-        {
-            const string Secret = "supersecret-shhh-value";
-            using (var hc = CreateTestContext())
-            {
-                hc.SecretMasker.AddValue(Secret);
-
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port, "ci-job");
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveDebuggerToReadyAsync(port);
-                    // Embed the secret in a step display name so it ends up in the rendered YAML.
-                    var step = NewActionRunner(GitHub.Runner.Worker.ActionRunStage.Main, $"Run {Secret} step").Object;
-                    await _debugger.OnJobStepsInitializedAsync(new[] { step }, Array.Empty<IStep>());
-
-                    // Sanity-check the raw view actually contains the secret;
-                    // otherwise the masking assertion below would pass vacuously.
-                    Assert.Contains(Secret, _debugger.ExecutionView.Yaml);
-
-                    var response = _debugger.HandleSource(MakeRequest("source", new SourceArguments { SourceReference = 1 }));
-                    Assert.True(response.Success);
-                    var body = Assert.IsType<SourceResponseBody>(response.Body);
-                    Assert.DoesNotContain(Secret, body.Content);
-                    Assert.Contains("***", body.Content);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task HandleStackTrace_MasksSecretsInSourcePath()
-        {
-            const string Secret = "secret-job-name-xyz";
-            using (var hc = CreateTestContext())
-            {
-                hc.SecretMasker.AddValue(Secret);
-
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                // Job name (== GitHub context "job") embeds the secret.
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port, Secret);
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveDebuggerToReadyAsync(port);
-                    var step = NewActionRunner(GitHub.Runner.Worker.ActionRunStage.Main, "Run").Object;
-                    await _debugger.OnJobStepsInitializedAsync(new[] { step }, Array.Empty<IStep>());
-
-                    _ = _debugger.OnStepStartingAsync(step, isFirstStep: false);
-                    await Task.Delay(50);
-
-                    var response = _debugger.HandleStackTrace(MakeRequest("stackTrace"));
-                    var body = Assert.IsType<StackTraceResponseBody>(response.Body);
-                    Assert.NotEmpty(body.StackFrames);
-                    foreach (var frame in body.StackFrames)
-                    {
-                        if (frame.Source != null)
-                        {
-                            Assert.DoesNotContain(Secret, frame.Source.Path ?? string.Empty);
-                            Assert.DoesNotContain(Secret, frame.Source.Name ?? string.Empty);
-                            Assert.Contains("***", frame.Source.Path ?? string.Empty);
-                        }
-                        Assert.DoesNotContain(Secret, frame.Name ?? string.Empty);
-                    }
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task HandleStackTrace_TwoFramesWhenStepping()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port, "ci-job");
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveDebuggerToReadyAsync(port);
-                    var step1 = NewActionRunner(GitHub.Runner.Worker.ActionRunStage.Main, "Step One").Object;
-                    var step2 = NewActionRunner(GitHub.Runner.Worker.ActionRunStage.Main, "Step Two", "actions/setup-node", "v3").Object;
-                    await _debugger.OnJobStepsInitializedAsync(new[] { step1, step2 }, Array.Empty<IStep>());
-
-                    // Fire-and-forget: first step pauses, but we just want _currentStep set.
-                    _ = _debugger.OnStepStartingAsync(step1, isFirstStep: false);
-                    await Task.Delay(50);
-
-                    var response = _debugger.HandleStackTrace(MakeRequest("stackTrace"));
-                    var body = Assert.IsType<StackTraceResponseBody>(response.Body);
-                    Assert.Equal(2, body.StackFrames.Count);
-
-                    var frame0 = body.StackFrames[0];
-                    Assert.Equal(1, frame0.Source.SourceReference);
-                    Assert.Equal(_debugger.ExecutionView.TryGetLineForStep(step1), frame0.Line);
-                    Assert.Equal("normal", frame0.PresentationHint);
-
-                    var frame1 = body.StackFrames[1];
-                    Assert.Equal(1, frame1.Line);
-                    Assert.Equal("subtle", frame1.PresentationHint);
-                    Assert.Equal(1, frame1.Source.SourceReference);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task HandleStackTrace_OneFrameWhenViewMissing()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port, "ci-job");
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveDebuggerToReadyAsync(port);
-                    var step = NewActionRunner(GitHub.Runner.Worker.ActionRunStage.Main, "Lonely").Object;
-                    // No view built — but pause the step so _currentStep is set.
-                    _ = _debugger.OnStepStartingAsync(step, isFirstStep: false);
-                    await Task.Delay(50);
-
-                    var response = _debugger.HandleStackTrace(MakeRequest("stackTrace"));
-                    var body = Assert.IsType<StackTraceResponseBody>(response.Body);
-                    Assert.Single(body.StackFrames);
-                    Assert.Null(body.StackFrames[0].Source);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task HandleStackTrace_NoFramesWhenIdle()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port, "ci-job");
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveDebuggerToReadyAsync(port);
-                    var response = _debugger.HandleStackTrace(MakeRequest("stackTrace"));
-                    var body = Assert.IsType<StackTraceResponseBody>(response.Body);
-                    Assert.Empty(body.StackFrames);
-                    Assert.Equal(0, body.TotalFrames);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task HandleLoadedSources_ReturnsExecutionView()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port, "ci-job");
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveDebuggerToReadyAsync(port);
-                    var step = NewActionRunner(GitHub.Runner.Worker.ActionRunStage.Main, "Run").Object;
-                    await _debugger.OnJobStepsInitializedAsync(new[] { step }, Array.Empty<IStep>());
-
-                    var response = _debugger.HandleLoadedSources(MakeRequest("loadedSources"));
-                    Assert.True(response.Success);
-                    var body = Assert.IsType<LoadedSourcesResponseBody>(response.Body);
-                    Assert.Single(body.Sources);
-                    Assert.Equal("execution.yml", body.Sources[0].Name);
-                    Assert.Equal("ci-job/execution.yml", body.Sources[0].Path);
-                    Assert.Equal(1, body.Sources[0].SourceReference);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task HandleLoadedSources_NoView_ReturnsEmpty()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port, "ci-job");
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveDebuggerToReadyAsync(port);
-                    var response = _debugger.HandleLoadedSources(MakeRequest("loadedSources"));
-                    Assert.True(response.Success);
-                    var body = Assert.IsType<LoadedSourcesResponseBody>(response.Body);
-                    Assert.Empty(body.Sources);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task HandleSetBreakpoints_ReturnsUnverifiedPlaceholders()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port, "ci-job");
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveDebuggerToReadyAsync(port);
-                    var step = NewActionRunner(GitHub.Runner.Worker.ActionRunStage.Main, "Run").Object;
-                    await _debugger.OnJobStepsInitializedAsync(new[] { step }, Array.Empty<IStep>());
-
-                    var args = new SetBreakpointsArguments
-                    {
-                        Source = new Source { SourceReference = 1 },
-                        Breakpoints = new System.Collections.Generic.List<SourceBreakpoint>
-                        {
-                            new SourceBreakpoint { Line = 5 },
-                            new SourceBreakpoint { Line = 10 },
-                            new SourceBreakpoint { Line = 15 },
-                        },
-                    };
-
-                    var response = _debugger.HandleSetBreakpoints(MakeRequest("setBreakpoints", args));
-                    Assert.True(response.Success);
-                    var body = Assert.IsType<SetBreakpointsResponseBody>(response.Body);
-                    Assert.Equal(3, body.Breakpoints.Count);
-                    Assert.All(body.Breakpoints, bp => Assert.False(bp.Verified));
-                    Assert.Equal(new[] { 5, 10, 15 }, body.Breakpoints.ConvertAll(b => b.Line ?? -1));
-                    Assert.All(body.Breakpoints, bp => Assert.False(string.IsNullOrEmpty(bp.Message)));
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task OnJobStepsInitialized_EmitsLoadedSourceNewEvent()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port, "ci-job");
-                await _debugger.StartAsync(jobContext.Object);
-                using var client = await ConnectClientAsync(port);
-                try
-                {
-                    var stream = client.GetStream();
-                    await SendRequestAsync(stream, new Request { Seq = 1, Type = "request", Command = "configurationDone" });
-                    await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5)); // configurationDone response
-                    await _debugger.WaitUntilReadyAsync();
-
-                    var step = NewActionRunner(GitHub.Runner.Worker.ActionRunStage.Main, "Run").Object;
-                    await _debugger.OnJobStepsInitializedAsync(new[] { step }, Array.Empty<IStep>());
-
-                    var msg = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
-                    Assert.Contains("\"event\":\"loadedSource\"", msg);
-                    Assert.Contains("\"reason\":\"new\"", msg);
-                    Assert.Contains("\"sourceReference\":1", msg);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task OnPostStepRegistered_EmitsLoadedSourceChangedEvent()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port, "ci-job");
-                await _debugger.StartAsync(jobContext.Object);
-                using var client = await ConnectClientAsync(port);
-                try
-                {
-                    var stream = client.GetStream();
-                    await SendRequestAsync(stream, new Request { Seq = 1, Type = "request", Command = "configurationDone" });
-                    await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
-                    await _debugger.WaitUntilReadyAsync();
-
-                    var main = NewActionRunner(GitHub.Runner.Worker.ActionRunStage.Main, "Run").Object;
-                    await _debugger.OnJobStepsInitializedAsync(new[] { main }, Array.Empty<IStep>());
-                    // Drain the "new" loadedSource event.
-                    await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
-
-                    var post = NewActionRunner(GitHub.Runner.Worker.ActionRunStage.Post, "Post Run", "actions/cache", "v3").Object;
-                    _debugger.OnPostStepRegistered(post);
-
-                    var msg = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
-                    Assert.Contains("\"event\":\"loadedSource\"", msg);
-                    Assert.Contains("\"reason\":\"changed\"", msg);
-                    Assert.Contains("\"sourceReference\":1", msg);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task StackTrace_LineUpdatesAsStepsAdvance()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port, "ci-job");
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveDebuggerToReadyAsync(port);
-                    var s1 = NewActionRunner(GitHub.Runner.Worker.ActionRunStage.Main, "Step 1", "a/b", "v1").Object;
-                    var s2 = NewActionRunner(GitHub.Runner.Worker.ActionRunStage.Main, "Step 2", "c/d", "v2").Object;
-                    await _debugger.OnJobStepsInitializedAsync(new[] { s1, s2 }, Array.Empty<IStep>());
-
-                    _ = _debugger.OnStepStartingAsync(s1, isFirstStep: true);
-                    await Task.Delay(50);
-
-                    var first = _debugger.HandleStackTrace(MakeRequest("stackTrace"));
-                    var firstBody = Assert.IsType<StackTraceResponseBody>(first.Body);
-                    int firstLine = firstBody.StackFrames[0].Line;
-                    Assert.Equal(_debugger.ExecutionView.TryGetLineForStep(s1), firstLine);
-
-                    _ = _debugger.OnStepStartingAsync(s2, isFirstStep: false);
-                    await Task.Delay(50);
-
-                    var second = _debugger.HandleStackTrace(MakeRequest("stackTrace"));
-                    var secondBody = Assert.IsType<StackTraceResponseBody>(second.Body);
-                    int secondLine = secondBody.StackFrames[0].Line;
-                    Assert.Equal(_debugger.ExecutionView.TryGetLineForStep(s2), secondLine);
-                    Assert.NotEqual(firstLine, secondLine);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
     }
 }

src/Test/L0/Worker/ExecutionContextL0.cs

@@ -7,7 +7,6 @@ using GitHub.DistributedTask.Pipelines.ContextData;
 using GitHub.DistributedTask.WebApi;
 using GitHub.Runner.Worker;
 using GitHub.Runner.Worker.Container;
-using GitHub.Runner.Worker.Dap;
 using GitHub.Runner.Worker.Handlers;
 using Moq;
 using Xunit;
@@ -406,7 +405,6 @@ namespace GitHub.Runner.Common.Tests.Worker
                 hc.EnqueueInstance(pagingLogger5.Object);
                 hc.EnqueueInstance(actionRunner1 as IActionRunner);
                 hc.EnqueueInstance(actionRunner2 as IActionRunner);
-                hc.SetSingleton(new Mock<IDapDebugger>().Object);
                 hc.SetSingleton(jobServerQueue.Object);
 
                 var jobContext = new Runner.Worker.ExecutionContext();
@@ -505,7 +503,6 @@ namespace GitHub.Runner.Common.Tests.Worker
                 hc.EnqueueInstance(pagingLogger5.Object);
                 hc.EnqueueInstance(actionRunner1 as IActionRunner);
                 hc.EnqueueInstance(actionRunner2 as IActionRunner);
-                hc.SetSingleton(new Mock<IDapDebugger>().Object);
                 hc.SetSingleton(jobServerQueue.Object);
 
                 var jobContext = new Runner.Worker.ExecutionContext();
@@ -547,75 +544,6 @@ namespace GitHub.Runner.Common.Tests.Worker
             }
         }
 
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void RegisterPostJobAction_DebuggerDisabled_DoesNotInvokeDapDebugger()
-        {
-            using (TestHostContext hc = CreateTestContext())
-            {
-                // Arrange: Create a job request message with EnableDebugger left at the default (false).
-                TaskOrchestrationPlanReference plan = new();
-                TimelineReference timeline = new();
-                Guid jobId = Guid.NewGuid();
-                string jobName = "some job name";
-                var jobRequest = new Pipelines.AgentJobRequestMessage(plan, timeline, jobId, jobName, jobName, null, null, null, new Dictionary<string, VariableValue>(), new List<MaskHint>(), new Pipelines.JobResources(), new Pipelines.ContextData.DictionaryContextData(), new Pipelines.WorkspaceOptions(), new List<Pipelines.ActionStep>(), null, null, null, null, null);
-                jobRequest.Resources.Repositories.Add(new Pipelines.RepositoryResource()
-                {
-                    Alias = Pipelines.PipelineConstants.SelfAlias,
-                    Id = "github",
-                    Version = "sha1"
-                });
-                jobRequest.ContextData["github"] = new Pipelines.ContextData.DictionaryContextData();
-
-                var pagingLogger = new Mock<IPagingLogger>();
-                var jobServerQueue = new Mock<IJobServerQueue>();
-                jobServerQueue.Setup(x => x.QueueTimelineRecordUpdate(It.IsAny<Guid>(), It.IsAny<TimelineRecord>()));
-                jobServerQueue.Setup(x => x.QueueWebConsoleLine(It.IsAny<Guid>(), It.IsAny<string>(), It.IsAny<long?>()));
-
-                var actionRunner = new ActionRunner();
-                actionRunner.Initialize(hc);
-
-                hc.EnqueueInstance(pagingLogger.Object);
-                hc.EnqueueInstance(pagingLogger.Object);
-                hc.EnqueueInstance(pagingLogger.Object);
-                hc.EnqueueInstance(pagingLogger.Object);
-                hc.EnqueueInstance(pagingLogger.Object);
-                hc.EnqueueInstance(pagingLogger.Object);
-                hc.EnqueueInstance(pagingLogger.Object);
-                hc.EnqueueInstance(actionRunner as IActionRunner);
-
-                // Register a strict mock IDapDebugger. If the production code calls
-                // ANY method on it, the test fails — proving the containment guard
-                // short-circuited before HostContext.GetService<IDapDebugger>().
-                var dapMock = new Mock<IDapDebugger>(MockBehavior.Strict);
-                hc.SetSingleton(dapMock.Object);
-                hc.SetSingleton(jobServerQueue.Object);
-
-                var jobContext = new Runner.Worker.ExecutionContext();
-                jobContext.Initialize(hc);
-                jobContext.InitializeJob(jobRequest, CancellationToken.None);
-
-                var action = jobContext.CreateChild(Guid.NewGuid(), "action_1", "action_1", null, null, 0);
-
-                var postRunner = hc.CreateService<IActionRunner>();
-                postRunner.Action = new Pipelines.ActionStep() { Id = Guid.NewGuid(), Name = "post", DisplayName = "Post", Reference = new Pipelines.RepositoryPathReference() { Name = "actions/action" } };
-                postRunner.Stage = ActionRunStage.Post;
-                postRunner.Condition = "always()";
-                postRunner.DisplayName = "post";
-
-                // Sanity: ensure the production code path actually believes the debugger is disabled.
-                Assert.True(jobContext.Global.Debugger == null || jobContext.Global.Debugger.Enabled == false);
-
-                // Act.
-                action.RegisterPostJobStep(postRunner);
-
-                // Assert: the debugger was never consulted on the non-debug path.
-                dapMock.VerifyNoOtherCalls();
-                Assert.Equal(1, jobContext.PostJobSteps.Count);
-            }
-        }
-
         [Fact]
         [Trait("Level", "L0")]
         [Trait("Category", "Worker")]

src/Test/L0/Worker/JobExecutionViewL0.cs

@@ -1,467 +0,0 @@
-using System;
-using System.Collections.Concurrent;
-using System.Collections.Generic;
-using System.Linq;
-using System.Threading.Tasks;
-using GitHub.Runner.Worker;
-using GitHub.Runner.Worker.Dap;
-using Moq;
-using Xunit;
-
-namespace GitHub.Runner.Common.Tests.Worker
-{
-    public sealed class JobExecutionViewL0
-    {
-        private static JobExecutionViewEntry MainEntry(string name)
-        {
-            return new JobExecutionViewEntry(JobExecutionPhase.Main, name, run: name);
-        }
-
-        private static IStep NewStep(string displayName = "step")
-        {
-            var mock = new Mock<IStep>();
-            mock.Setup(s => s.DisplayName).Returns(displayName);
-            return mock.Object;
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Constructor_RendersEmptyView()
-        {
-            var view = new JobExecutionView("my-job");
-
-            Assert.Equal(0, view.EntryCount);
-            Assert.Contains("# Job: my-job", view.Yaml);
-            Assert.Contains("- step: Setup job", view.Yaml);
-            Assert.Contains("- step: Complete job", view.Yaml);
-
-            // Only the two synthetic boundaries appear.
-            int stepCount = view.Yaml.Split("- step: ").Length - 1;
-            Assert.Equal(2, stepCount);
-        }
-
-        [Theory]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        [InlineData(null)]
-        [InlineData("")]
-        [InlineData("   ")]
-        public void Constructor_ThrowsOnInvalidJobId(string jobId)
-        {
-            Assert.Throws<ArgumentException>(() => new JobExecutionView(jobId));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Append_IncrementsEntryCount()
-        {
-            var view = new JobExecutionView("j");
-
-            int line0 = view.Append(MainEntry("a"));
-            int line1 = view.Append(MainEntry("b"));
-            int line2 = view.Append(MainEntry("c"));
-
-            Assert.Equal(3, view.EntryCount);
-            Assert.True(line0 < line1);
-            Assert.True(line1 < line2);
-            Assert.Equal(line0, view.GetLine(0));
-            Assert.Equal(line1, view.GetLine(1));
-            Assert.Equal(line2, view.GetLine(2));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Append_PreservesPriorEntryLines()
-        {
-            var view = new JobExecutionView("j");
-
-            int l0 = view.Append(MainEntry("a"));
-            int l1 = view.Append(MainEntry("b"));
-            int l2 = view.Append(MainEntry("c"));
-
-            view.Append(MainEntry("d"));
-            Assert.Equal(l0, view.GetLine(0));
-            Assert.Equal(l1, view.GetLine(1));
-            Assert.Equal(l2, view.GetLine(2));
-
-            view.Append(MainEntry("e"));
-            Assert.Equal(l0, view.GetLine(0));
-            Assert.Equal(l1, view.GetLine(1));
-            Assert.Equal(l2, view.GetLine(2));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Append_RegistersStepIdentity()
-        {
-            var view = new JobExecutionView("j");
-            var step = NewStep();
-
-            int line = view.Append(MainEntry("a"), step);
-
-            Assert.Equal(line, view.GetLine(0));
-            Assert.Equal(line, view.TryGetLineForStep(step));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Append_NullStepIdentity_StillAppends()
-        {
-            var view = new JobExecutionView("j");
-
-            view.Append(MainEntry("a"), stepIdentity: null);
-
-            Assert.Equal(1, view.EntryCount);
-            Assert.Null(view.TryGetLineForStep(null));
-            Assert.Contains("- step: a", view.Yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Append_DuplicateStepIdentity_Throws()
-        {
-            var view = new JobExecutionView("j");
-            var step = NewStep();
-
-            view.Append(MainEntry("a"), step);
-            Assert.Throws<InvalidOperationException>(() => view.Append(MainEntry("b"), step));
-
-            // State preserved: only the first entry is present.
-            Assert.Equal(1, view.EntryCount);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Append_NullEntry_Throws()
-        {
-            var view = new JobExecutionView("j");
-            Assert.Throws<ArgumentNullException>(() => view.Append(null));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void AppendRange_AppendsAllAndRendersOnce()
-        {
-            var view = new JobExecutionView("j");
-            var steps = Enumerable.Range(0, 5).Select(i => NewStep("s" + i)).ToList();
-            var items = steps
-                .Select((s, i) => (entry: MainEntry("e" + i), stepIdentity: s))
-                .ToList();
-
-            view.AppendRange(items);
-
-            Assert.Equal(5, view.EntryCount);
-            for (int i = 0; i < 5; i++)
-            {
-                int line = view.GetLine(i);
-                Assert.Equal(line, view.TryGetLineForStep(steps[i]));
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void AppendRange_RejectsDuplicateInInput()
-        {
-            var view = new JobExecutionView("j");
-            var dup = NewStep();
-            var items = new List<(JobExecutionViewEntry, IStep)>
-            {
-                (MainEntry("a"), dup),
-                (MainEntry("b"), dup),
-            };
-
-            Assert.Throws<InvalidOperationException>(() => view.AppendRange(items));
-            Assert.Equal(0, view.EntryCount);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void AppendRange_RejectsOverlapWithExisting()
-        {
-            var view = new JobExecutionView("j");
-            var step = NewStep();
-            view.Append(MainEntry("a"), step);
-
-            var items = new List<(JobExecutionViewEntry, IStep)>
-            {
-                (MainEntry("b"), step),
-            };
-
-            Assert.Throws<InvalidOperationException>(() => view.AppendRange(items));
-            Assert.Equal(1, view.EntryCount);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void AppendRange_NullItems_Throws()
-        {
-            var view = new JobExecutionView("j");
-            Assert.Throws<ArgumentNullException>(() => view.AppendRange(null));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void TryGetLineForStep_NullStep_ReturnsNull()
-        {
-            var view = new JobExecutionView("j");
-            Assert.Null(view.TryGetLineForStep(null));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void TryGetLineForStep_UnknownStep_ReturnsNull()
-        {
-            var view = new JobExecutionView("j");
-            var step = NewStep();
-            Assert.Null(view.TryGetLineForStep(step));
-        }
-
-        [Theory]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        [InlineData(-1)]
-        [InlineData(2)]
-        public void GetLine_OutOfRange_Throws(int index)
-        {
-            var view = new JobExecutionView("j");
-            view.Append(MainEntry("a"));
-            view.Append(MainEntry("b"));
-
-            Assert.Throws<ArgumentOutOfRangeException>(() => view.GetLine(index));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Yaml_UpdatesAfterAppend()
-        {
-            var view = new JobExecutionView("j");
-            view.Append(MainEntry("first"));
-            string before = view.Yaml;
-            Assert.Contains("- step: first", before);
-
-            view.Append(MainEntry("second"));
-            string after = view.Yaml;
-
-            Assert.Contains("- step: first", after);
-            Assert.Contains("- step: second", after);
-            Assert.NotEqual(before, after);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Yaml_AlwaysEndsWithCleanupBoundary()
-        {
-            var view = new JobExecutionView("j");
-            Assert.EndsWith("cleanup:\n  - step: Complete job\n", view.Yaml);
-
-            view.Append(MainEntry("a"));
-            Assert.EndsWith("cleanup:\n  - step: Complete job\n", view.Yaml);
-
-            view.Append(MainEntry("b"));
-            view.Append(MainEntry("c"));
-            Assert.EndsWith("cleanup:\n  - step: Complete job\n", view.Yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Append_WithMatchKey_TracksUnclaimed()
-        {
-            var view = new JobExecutionView("j");
-
-            int line = view.Append(MainEntry("placeholder"), stepIdentity: null, matchKey: "k1");
-
-            var step = NewStep("real");
-            int? claimed = view.TryClaim("k1", step);
-            Assert.Equal(line, claimed);
-            Assert.Equal(line, view.TryGetLineForStep(step));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void TryClaim_UnknownKey_ReturnsNull()
-        {
-            var view = new JobExecutionView("j");
-            view.Append(MainEntry("a"), stepIdentity: null, matchKey: "k1");
-
-            Assert.Null(view.TryClaim("nope", NewStep()));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void TryClaim_AlreadyClaimed_ReturnsNull()
-        {
-            var view = new JobExecutionView("j");
-            view.Append(MainEntry("a"), stepIdentity: null, matchKey: "k1");
-
-            var first = NewStep("first");
-            Assert.NotNull(view.TryClaim("k1", first));
-
-            var second = NewStep("second");
-            Assert.Null(view.TryClaim("k1", second));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void TryClaim_StepAlreadyRegistered_ReturnsNull()
-        {
-            var view = new JobExecutionView("j");
-            var step = NewStep();
-            // Step is registered for the first entry.
-            view.Append(MainEntry("a"), step);
-            // A placeholder is registered for the second entry.
-            view.Append(MainEntry("b"), stepIdentity: null, matchKey: "k1");
-
-            // Trying to claim the placeholder with the already-registered
-            // step must return null (defensive — would otherwise double-bind).
-            Assert.Null(view.TryClaim("k1", step));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Append_DuplicateMatchKey_Throws()
-        {
-            var view = new JobExecutionView("j");
-            view.Append(MainEntry("a"), stepIdentity: null, matchKey: "k1");
-
-            Assert.Throws<InvalidOperationException>(
-                () => view.Append(MainEntry("b"), stepIdentity: null, matchKey: "k1"));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Append_MatchKeyNull_BehavesLikeOldOverload()
-        {
-            var view = new JobExecutionView("j");
-            var step = NewStep();
-
-            int line = view.Append(MainEntry("a"), step);
-
-            Assert.Equal(line, view.GetLine(0));
-            Assert.Equal(line, view.TryGetLineForStep(step));
-            // TryClaim with any key must return null since no matchKey was registered.
-            Assert.Null(view.TryClaim("anything", NewStep()));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void TryClaim_AfterClaim_TryGetLineForStepResolves()
-        {
-            var view = new JobExecutionView("j");
-            int line = view.Append(MainEntry("placeholder"), stepIdentity: null, matchKey: "k1");
-
-            var step = NewStep();
-            Assert.Equal(line, view.TryClaim("k1", step));
-            Assert.Equal(line, view.TryGetLineForStep(step));
-
-            // And a later Append doesn't lose the claim (Render rebuilds
-            // the IStep -> line map from the persisted identities).
-            view.Append(MainEntry("b"));
-            Assert.Equal(line, view.TryGetLineForStep(step));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void TryClaim_NullArgs_Throws()
-        {
-            var view = new JobExecutionView("j");
-            Assert.Throws<ArgumentNullException>(() => view.TryClaim(null, NewStep()));
-            Assert.Throws<ArgumentNullException>(() => view.TryClaim("k", null));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task ConcurrentAppends_DontCorruptState()
-        {
-            var view = new JobExecutionView("j");
-            const int N = 50;
-            var steps = Enumerable.Range(0, N).Select(i => NewStep("s" + i)).ToList();
-            var returnedLines = new ConcurrentBag<int>();
-
-            var tasks = Enumerable.Range(0, N).Select(i => Task.Run(() =>
-            {
-                int line = view.Append(MainEntry("e" + i), steps[i]);
-                returnedLines.Add(line);
-            })).ToArray();
-
-            await Task.WhenAll(tasks);
-
-            Assert.Equal(N, view.EntryCount);
-            Assert.Equal(N, returnedLines.Distinct().Count());
-
-            // Every step identity resolves to some line in [0, N).
-            var entryLines = Enumerable.Range(0, N).Select(view.GetLine).ToHashSet();
-            Assert.Equal(N, entryLines.Count);
-            foreach (var step in steps)
-            {
-                int? line = view.TryGetLineForStep(step);
-                Assert.NotNull(line);
-                Assert.Contains(line.Value, entryLines);
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void TryMarkSkipped_MarksUnclaimedPlaceholder()
-        {
-            var view = new JobExecutionView("j");
-            var postEntry = new JobExecutionViewEntry(JobExecutionPhase.Post, "Post X", uses: "actions/x@v1");
-            view.Append(postEntry, stepIdentity: null, matchKey: "k1");
-
-            Assert.True(view.TryMarkSkipped("k1"));
-            Assert.True(postEntry.IsSkipped);
-            Assert.Contains("(skipped — main step did not execute)", view.Yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void TryMarkSkipped_ReturnsFalseForUnknownKey()
-        {
-            var view = new JobExecutionView("j");
-            Assert.False(view.TryMarkSkipped("nope"));
-            Assert.DoesNotContain("(skipped", view.Yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void TryMarkSkipped_ReturnsFalseForClaimedPlaceholder()
-        {
-            var view = new JobExecutionView("j");
-            var postEntry = new JobExecutionViewEntry(JobExecutionPhase.Post, "Post X", uses: "actions/x@v1");
-            view.Append(postEntry, stepIdentity: null, matchKey: "k1");
-
-            var step = NewStep("real-post");
-            Assert.NotNull(view.TryClaim("k1", step));
-
-            // Already claimed — must not mark as skipped.
-            Assert.False(view.TryMarkSkipped("k1"));
-            Assert.False(postEntry.IsSkipped);
-        }
-    }
-}

src/Test/L0/Worker/JobExecutionViewLifecycleL0.cs

@@ -1,703 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Net;
-using System.Net.Sockets;
-using System.Runtime.CompilerServices;
-using System.Text;
-using System.Threading;
-using System.Threading.Tasks;
-using GitHub.DistributedTask.Pipelines;
-using GitHub.DistributedTask.WebApi;
-using GitHub.Runner.Worker;
-using GitHub.Runner.Worker.Dap;
-using Moq;
-using Newtonsoft.Json;
-using Xunit;
-
-namespace GitHub.Runner.Common.Tests.Worker
-{
-    public sealed class JobExecutionViewLifecycleL0
-    {
-        private DapDebugger _debugger;
-
-        private TestHostContext CreateTestContext([CallerMemberName] string testName = "")
-        {
-            var hc = new TestHostContext(this, testName);
-            _debugger = new DapDebugger();
-            _debugger.Initialize(hc);
-            _debugger.SkipTunnelRelay = true;
-            _debugger.SkipWebSocketBridge = true;
-            return hc;
-        }
-
-        private static ushort GetFreePort()
-        {
-            using var listener = new TcpListener(IPAddress.Loopback, 0);
-            listener.Start();
-            return (ushort)((IPEndPoint)listener.LocalEndpoint).Port;
-        }
-
-        private static Mock<IExecutionContext> CreateJobContextWithTunnel(CancellationToken cancellationToken, ushort port, string jobName = "ci-job")
-        {
-            var tunnel = new GitHub.DistributedTask.Pipelines.DebuggerTunnelInfo
-            {
-                TunnelId = "test-tunnel",
-                ClusterId = "test-cluster",
-                HostToken = "test-token",
-                Port = port
-            };
-            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 });
-            jobContext
-                .Setup(x => x.GetGitHubContext(It.IsAny<string>()))
-                .Returns((string contextName) => string.Equals(contextName, "job", StringComparison.Ordinal) ? jobName : null);
-            return jobContext;
-        }
-
-        private static async Task DriveToReadyAsync(DapDebugger debugger, int port)
-        {
-            var waitTask = debugger.WaitUntilReadyAsync();
-            var client = new TcpClient();
-            await client.ConnectAsync(IPAddress.Loopback, port);
-            var stream = client.GetStream();
-            var request = new Request { Seq = 1, Type = "request", Command = "configurationDone" };
-            var json = JsonConvert.SerializeObject(request);
-            var body = Encoding.UTF8.GetBytes(json);
-            var header = Encoding.ASCII.GetBytes($"Content-Length: {body.Length}\r\n\r\n");
-            await stream.WriteAsync(header, 0, header.Length);
-            await stream.WriteAsync(body, 0, body.Length);
-            await stream.FlushAsync();
-            await waitTask;
-            // Keep client alive by holding a reference via GC root in caller scope.
-            // We deliberately don't dispose here; tests dispose the context.
-            _ = client;
-        }
-
-        private static Mock<IActionRunner> NewActionRunner(ActionRunStage stage, string displayName, string actionName = "actions/checkout", string actionRef = "v4", Guid actionId = default)
-        {
-            var mock = new Mock<IActionRunner>();
-            mock.SetupGet(x => x.Stage).Returns(stage);
-            mock.SetupGet(x => x.DisplayName).Returns(displayName);
-            mock.SetupGet(x => x.Action).Returns(new ActionStep
-            {
-                Id = actionId,
-                Reference = new RepositoryPathReference { Name = actionName, Ref = actionRef },
-            });
-            return mock;
-        }
-
-        private static Mock<IActionRunner> NewSelfActionRunner(ActionRunStage stage, string displayName, Guid actionId = default)
-        {
-            // RepositoryType = "self" — the predictor must skip these.
-            var mock = new Mock<IActionRunner>();
-            mock.SetupGet(x => x.Stage).Returns(stage);
-            mock.SetupGet(x => x.DisplayName).Returns(displayName);
-            mock.SetupGet(x => x.Action).Returns(new ActionStep
-            {
-                Id = actionId,
-                Reference = new RepositoryPathReference
-                {
-                    RepositoryType = GitHub.DistributedTask.Pipelines.PipelineConstants.SelfAlias,
-                    Path = "./.github/actions/local",
-                },
-            });
-            return mock;
-        }
-
-        private static Mock<IActionRunner> NewScriptActionRunner(ActionRunStage stage, string displayName, Guid actionId = default)
-        {
-            // ScriptReference — a `run:` step. Not a RepositoryPathReference,
-            // so the predictor's pattern match falls through.
-            var mock = new Mock<IActionRunner>();
-            mock.SetupGet(x => x.Stage).Returns(stage);
-            mock.SetupGet(x => x.DisplayName).Returns(displayName);
-            mock.SetupGet(x => x.Action).Returns(new ActionStep
-            {
-                Id = actionId,
-                Reference = new ScriptReference(),
-            });
-            return mock;
-        }
-
-        // IActionManager mock that returns specific Definitions per action by
-        // matching on the action's reference Name. Actions whose name is not
-        // in the map get a Definition with HasPost = false.
-        private static Mock<IActionManager> NewActionManagerWithPost(params string[] actionNamesWithPost)
-        {
-            var withPost = new HashSet<string>(actionNamesWithPost, StringComparer.Ordinal);
-            var mock = new Mock<IActionManager>();
-            mock.Setup(x => x.LoadAction(It.IsAny<IExecutionContext>(), It.IsAny<ActionStep>()))
-                .Returns((IExecutionContext _, ActionStep step) =>
-                {
-                    var name = (step.Reference as RepositoryPathReference)?.Name ?? "";
-                    return new Definition
-                    {
-                        Data = new ActionDefinitionData
-                        {
-                            Execution = withPost.Contains(name)
-                                ? new NodeJSActionExecutionData { Post = "post.js" }
-                                : new NodeJSActionExecutionData(),
-                        },
-                    };
-                });
-            return mock;
-        }
-
-        private static IStep NewJobExtensionRunner(string displayName)
-        {
-            return new JobExtensionRunner(
-                runAsync: (_, __) => Task.CompletedTask,
-                condition: null,
-                displayName: displayName,
-                data: null);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task OnJobStepsInitialized_NotActive_NoOps()
-        {
-            using (CreateTestContext())
-            {
-                var step = NewActionRunner(ActionRunStage.Main, "Run").Object;
-
-                await _debugger.OnJobStepsInitializedAsync(new[] { step }, Array.Empty<IStep>());
-
-                Assert.Null(_debugger.ExecutionView);
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task OnPostStepRegistered_NotActive_NoOps()
-        {
-            using (CreateTestContext())
-            {
-                var step = NewActionRunner(ActionRunStage.Post, "Post Run").Object;
-                _debugger.OnPostStepRegistered(step); // must not throw
-                Assert.Null(_debugger.ExecutionView);
-                await Task.CompletedTask;
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task OnJobStepsInitialized_Active_BuildsView()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveToReadyAsync(_debugger, port);
-
-                    var main1 = NewActionRunner(ActionRunStage.Main, "Run actions/checkout@v4").Object;
-                    var main2 = NewActionRunner(ActionRunStage.Main, "Run actions/setup-node@v3", "actions/setup-node", "v3").Object;
-                    var jobExt = NewJobExtensionRunner("Set up job");
-                    var post1 = NewActionRunner(ActionRunStage.Post, "Post Run actions/checkout@v4").Object;
-
-                    await _debugger.OnJobStepsInitializedAsync(
-                        new IStep[] { main1, jobExt, main2 },
-                        new IStep[] { post1 });
-
-                    var view = _debugger.ExecutionView;
-                    Assert.NotNull(view);
-                    Assert.Equal(3, view.EntryCount); // jobExt filtered out
-                    Assert.Contains("Run actions/checkout@v4", view.Yaml);
-                    Assert.Contains("Run actions/setup-node@v3", view.Yaml);
-                    Assert.Contains("Post Run actions/checkout@v4", view.Yaml);
-                    Assert.NotNull(view.TryGetLineForStep(main1));
-                    Assert.NotNull(view.TryGetLineForStep(main2));
-                    Assert.NotNull(view.TryGetLineForStep(post1));
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task OnJobStepsInitialized_PreservesQueueOrder()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveToReadyAsync(_debugger, port);
-
-                    var s1 = NewActionRunner(ActionRunStage.Main, "Step 1", "a/b", "v1").Object;
-                    var s2 = NewActionRunner(ActionRunStage.Main, "Step 2", "c/d", "v2").Object;
-                    var s3 = NewActionRunner(ActionRunStage.Main, "Step 3", "e/f", "v3").Object;
-
-                    await _debugger.OnJobStepsInitializedAsync(new[] { s1, s2, s3 }, Array.Empty<IStep>());
-
-                    var view = _debugger.ExecutionView;
-                    Assert.Equal(3, view.EntryCount);
-                    var l1 = view.TryGetLineForStep(s1);
-                    var l2 = view.TryGetLineForStep(s2);
-                    var l3 = view.TryGetLineForStep(s3);
-                    Assert.NotNull(l1);
-                    Assert.NotNull(l2);
-                    Assert.NotNull(l3);
-                    Assert.True(l1 < l2);
-                    Assert.True(l2 < l3);
-                    Assert.Equal(view.GetLine(0), l1);
-                    Assert.Equal(view.GetLine(1), l2);
-                    Assert.Equal(view.GetLine(2), l3);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task OnPostStepRegistered_AppendsToView()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveToReadyAsync(_debugger, port);
-
-                    var main1 = NewActionRunner(ActionRunStage.Main, "Run actions/checkout@v4").Object;
-                    await _debugger.OnJobStepsInitializedAsync(new[] { main1 }, Array.Empty<IStep>());
-                    Assert.Equal(1, _debugger.ExecutionView.EntryCount);
-
-                    var post1 = NewActionRunner(ActionRunStage.Post, "Post Run actions/cache@v3", "actions/cache", "v3").Object;
-                    _debugger.OnPostStepRegistered(post1);
-
-                    var view = _debugger.ExecutionView;
-                    Assert.Equal(2, view.EntryCount);
-                    Assert.Contains("Post Run actions/cache@v3", view.Yaml);
-                    Assert.NotNull(view.TryGetLineForStep(post1));
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task OnPostStepRegistered_BeforeViewBuilt_NoOps()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveToReadyAsync(_debugger, port);
-
-                    var post = NewActionRunner(ActionRunStage.Post, "Post Run").Object;
-                    _debugger.OnPostStepRegistered(post); // must not throw
-
-                    Assert.Null(_debugger.ExecutionView);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task OnPostStepRegistered_DuplicateStep_DoesNotThrow()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveToReadyAsync(_debugger, port);
-                    await _debugger.OnJobStepsInitializedAsync(Array.Empty<IStep>(), Array.Empty<IStep>());
-
-                    var post = NewActionRunner(ActionRunStage.Post, "Post Run").Object;
-                    _debugger.OnPostStepRegistered(post);
-                    _debugger.OnPostStepRegistered(post); // duplicate, must be silently ignored
-
-                    Assert.Equal(1, _debugger.ExecutionView.EntryCount);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task OnPostStepRegistered_FilteredStep_NoOps()
-        {
-            using (CreateTestContext())
-            {
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveToReadyAsync(_debugger, port);
-                    await _debugger.OnJobStepsInitializedAsync(Array.Empty<IStep>(), Array.Empty<IStep>());
-
-                    var before = _debugger.ExecutionView.EntryCount;
-                    _debugger.OnPostStepRegistered(NewJobExtensionRunner("Cleanup"));
-                    Assert.Equal(before, _debugger.ExecutionView.EntryCount);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        // ---- Predictive Post-step synthesis ----
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task OnJobStepsInitialized_PredictsPostForActionsWithHasPost()
-        {
-            using (var hc = CreateTestContext())
-            {
-                hc.SetSingleton<IActionManager>(NewActionManagerWithPost("actions/has-post").Object);
-
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveToReadyAsync(_debugger, port);
-
-                    var withPost = NewActionRunner(ActionRunStage.Main, "Run actions/has-post@v1", "actions/has-post", "v1", actionId: Guid.NewGuid()).Object;
-                    var noPost = NewActionRunner(ActionRunStage.Main, "Run actions/no-post@v1", "actions/no-post", "v1", actionId: Guid.NewGuid()).Object;
-
-                    await _debugger.OnJobStepsInitializedAsync(new[] { withPost, noPost }, Array.Empty<IStep>());
-
-                    var view = _debugger.ExecutionView;
-                    Assert.NotNull(view);
-                    // 2 main entries + 1 predicted post placeholder.
-                    Assert.Equal(3, view.EntryCount);
-                    Assert.Contains("post:\n", view.Yaml);
-                    Assert.Contains("Post Run actions/has-post@v1", view.Yaml);
-                    Assert.DoesNotContain("Post Run actions/no-post@v1", view.Yaml);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task OnJobStepsInitialized_PostPredictionsInReverseOrder()
-        {
-            using (var hc = CreateTestContext())
-            {
-                // Both actions have post — predictions must render in
-                // reverse declaration order to mirror the runner's LIFO
-                // post-execution order.
-                hc.SetSingleton<IActionManager>(NewActionManagerWithPost("actions/a", "actions/b").Object);
-
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveToReadyAsync(_debugger, port);
-
-                    var aMain = NewActionRunner(ActionRunStage.Main, "Run actions/a@v1", "actions/a", "v1", actionId: Guid.NewGuid()).Object;
-                    var bMain = NewActionRunner(ActionRunStage.Main, "Run actions/b@v1", "actions/b", "v1", actionId: Guid.NewGuid()).Object;
-
-                    await _debugger.OnJobStepsInitializedAsync(new[] { aMain, bMain }, Array.Empty<IStep>());
-
-                    string yaml = _debugger.ExecutionView.Yaml;
-                    int idxPostB = yaml.IndexOf("Post Run actions/b@v1", StringComparison.Ordinal);
-                    int idxPostA = yaml.IndexOf("Post Run actions/a@v1", StringComparison.Ordinal);
-                    Assert.True(idxPostB > 0 && idxPostA > 0, "both post placeholders expected");
-                    // Reverse declaration order: Post B appears BEFORE Post A.
-                    Assert.True(idxPostB < idxPostA, $"expected Post B before Post A (b={idxPostB} a={idxPostA})");
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task OnJobStepsInitialized_SkipsScriptSteps()
-        {
-            using (var hc = CreateTestContext())
-            {
-                // Even if the action manager would say HasPost, the predictor
-                // must skip script run-steps because their reference is not
-                // a RepositoryPathReference.
-                hc.SetSingleton<IActionManager>(NewActionManagerWithPost(/* nothing */).Object);
-
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveToReadyAsync(_debugger, port);
-
-                    var script = NewScriptActionRunner(ActionRunStage.Main, "Run script", Guid.NewGuid()).Object;
-                    await _debugger.OnJobStepsInitializedAsync(new[] { script }, Array.Empty<IStep>());
-
-                    var view = _debugger.ExecutionView;
-                    Assert.NotNull(view);
-                    Assert.DoesNotContain("post:\n", view.Yaml);
-                    Assert.DoesNotContain("Post ", view.Yaml);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task OnJobStepsInitialized_SkipsSelfActions()
-        {
-            using (var hc = CreateTestContext())
-            {
-                // Self-action: ActionRunner.cs:106 guards against creating a
-                // Post for self-repository references. The predictor mirrors
-                // that, regardless of what the manifest reports.
-                hc.SetSingleton<IActionManager>(NewActionManagerWithPost("anything").Object);
-
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveToReadyAsync(_debugger, port);
-
-                    var selfRunner = NewSelfActionRunner(ActionRunStage.Main, "Run ./local-action", Guid.NewGuid()).Object;
-                    await _debugger.OnJobStepsInitializedAsync(new[] { selfRunner }, Array.Empty<IStep>());
-
-                    Assert.DoesNotContain("post:\n", _debugger.ExecutionView.Yaml);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task OnPostStepRegistered_ClaimsExistingPlaceholder()
-        {
-            using (var hc = CreateTestContext())
-            {
-                hc.SetSingleton<IActionManager>(NewActionManagerWithPost("actions/has-post").Object);
-
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveToReadyAsync(_debugger, port);
-
-                    var actionId = Guid.NewGuid();
-                    var mainRunner = NewActionRunner(ActionRunStage.Main, "Run actions/has-post@v1", "actions/has-post", "v1", actionId: actionId).Object;
-                    await _debugger.OnJobStepsInitializedAsync(new[] { mainRunner }, Array.Empty<IStep>());
-
-                    var view = _debugger.ExecutionView;
-                    int before = view.EntryCount;
-                    Assert.Equal(2, before); // main + predicted post placeholder
-
-                    // The real Post IActionRunner shares the same Action.Id
-                    // as the Main runner (ActionRunner.cs:131).
-                    var postRunner = NewActionRunner(ActionRunStage.Post, "Post actions/has-post@v1", "actions/has-post", "v1", actionId: actionId).Object;
-                    _debugger.OnPostStepRegistered(postRunner);
-
-                    // No new entry: the placeholder was claimed.
-                    Assert.Equal(before, view.EntryCount);
-                    Assert.NotNull(view.TryGetLineForStep(postRunner));
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task OnPostStepRegistered_UnpredictedFallsBackToAppend()
-        {
-            using (var hc = CreateTestContext())
-            {
-                // Manager returns no HasPost — no predictions made.
-                hc.SetSingleton<IActionManager>(NewActionManagerWithPost(/* nothing */).Object);
-
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveToReadyAsync(_debugger, port);
-
-                    var mainRunner = NewActionRunner(ActionRunStage.Main, "Run actions/a@v1", "actions/a", "v1", actionId: Guid.NewGuid()).Object;
-                    await _debugger.OnJobStepsInitializedAsync(new[] { mainRunner }, Array.Empty<IStep>());
-
-                    var view = _debugger.ExecutionView;
-                    int before = view.EntryCount;
-                    Assert.Equal(1, before); // just main, no predicted post
-
-                    var unpredictedPost = NewActionRunner(ActionRunStage.Post, "Post Surprise", "actions/surprise", "v1", actionId: Guid.NewGuid()).Object;
-                    _debugger.OnPostStepRegistered(unpredictedPost);
-
-                    // Falls back to Append.
-                    Assert.Equal(before + 1, view.EntryCount);
-                    Assert.NotNull(view.TryGetLineForStep(unpredictedPost));
-                    Assert.Contains("Post Surprise", view.Yaml);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task OnPostStepRegistered_DuplicateClaim_NoDoubleEntry()
-        {
-            using (var hc = CreateTestContext())
-            {
-                hc.SetSingleton<IActionManager>(NewActionManagerWithPost("actions/has-post").Object);
-
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveToReadyAsync(_debugger, port);
-
-                    var actionId = Guid.NewGuid();
-                    var mainRunner = NewActionRunner(ActionRunStage.Main, "Run actions/has-post@v1", "actions/has-post", "v1", actionId: actionId).Object;
-                    await _debugger.OnJobStepsInitializedAsync(new[] { mainRunner }, Array.Empty<IStep>());
-                    Assert.Equal(2, _debugger.ExecutionView.EntryCount);
-
-                    // First registration claims the placeholder.
-                    var post1 = NewActionRunner(ActionRunStage.Post, "Post actions/has-post@v1", "actions/has-post", "v1", actionId: actionId).Object;
-                    _debugger.OnPostStepRegistered(post1);
-                    Assert.Equal(2, _debugger.ExecutionView.EntryCount);
-
-                    // Second registration with the same Action.Id but a
-                    // different IStep: TryClaim returns null (already
-                    // claimed). Falls through to Append. But the entry
-                    // it builds matches no existing step, so a new entry
-                    // would be added — UNLESS we constructed the second
-                    // post as a duplicate IStep registration of the same
-                    // step. Here we intentionally pass the same `post1`
-                    // step a second time — Append will reject the
-                    // already-registered step, the handler swallows it.
-                    _debugger.OnPostStepRegistered(post1);
-
-                    Assert.Equal(2, _debugger.ExecutionView.EntryCount);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task OnStepCompleted_SkippedMainStep_MarksPostPlaceholder()
-        {
-            using (var hc = CreateTestContext())
-            {
-                hc.SetSingleton<IActionManager>(NewActionManagerWithPost("actions/has-post").Object);
-
-                var port = GetFreePort();
-                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
-                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
-                await _debugger.StartAsync(jobContext.Object);
-                try
-                {
-                    await DriveToReadyAsync(_debugger, port);
-
-                    var actionId = Guid.NewGuid();
-                    var mainMock = NewActionRunner(ActionRunStage.Main, "Run actions/has-post@v1", "actions/has-post", "v1", actionId: actionId);
-                    var execCtx = new Mock<IExecutionContext>();
-                    execCtx.SetupGet(x => x.Result).Returns(TaskResult.Skipped);
-                    mainMock.SetupGet(x => x.ExecutionContext).Returns(execCtx.Object);
-
-                    await _debugger.OnJobStepsInitializedAsync(new[] { mainMock.Object }, Array.Empty<IStep>());
-
-                    var view = _debugger.ExecutionView;
-                    Assert.Equal(2, view.EntryCount); // main + predicted post placeholder
-                    Assert.DoesNotContain("(skipped", view.Yaml);
-
-                    _debugger.OnStepCompleted(mainMock.Object);
-
-                    Assert.Equal(2, _debugger.ExecutionView.EntryCount);
-                    Assert.Contains("(skipped — main step did not execute)", _debugger.ExecutionView.Yaml);
-                    // Inline annotation must not have introduced a new line.
-                    Assert.Equal(view.Yaml.Split('\n').Length, _debugger.ExecutionView.Yaml.Split('\n').Length);
-                }
-                finally
-                {
-                    await _debugger.StopAsync();
-                }
-            }
-        }
-    }
-}

src/Test/L0/Worker/JobExecutionViewRendererL0.cs

@@ -1,617 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using GitHub.Runner.Worker.Dap;
-using Xunit;
-
-namespace GitHub.Runner.Common.Tests.Worker
-{
-    public sealed class JobExecutionViewRendererL0
-    {
-        // Verbatim expected YAML for the design doc's "Worked example".
-        // The render output is structured as phase-keyed top-level sections;
-        // there is no per-entry `phase:` field. The setup: and cleanup:
-        // sections always render; pre:/main:/post: render only when
-        // they contain at least one entry. The Main entries surface
-        // user-authored step parameters pre-evaluation (no expression
-        // substitution); Pre/Post entries stay minimal.
-        private const string ExpectedWorkedExampleYaml =
-            "# Job: build\n" +
-            "# Runner execution plan — read-only.\n" +
-            "\n" +
-            "setup:\n" +
-            "  - step: Setup job\n" +
-            "\n" +
-            "pre:\n" +
-            "  - step: Pre actions/checkout@v4\n" +
-            "    action: actions/checkout@v4\n" +
-            "  - step: Pre actions/cache@v5\n" +
-            "    action: actions/cache@v5\n" +
-            "\n" +
-            "main:\n" +
-            "  - step: actions/checkout@v4\n" +
-            "    uses: actions/checkout@v4\n" +
-            "    source: .github/workflows/ci.yml:10\n" +
-            "  - step: Cache Primes\n" +
-            "    id: cache-primes\n" +
-            "    uses: actions/cache@v5\n" +
-            "    with:\n" +
-            "      path: prime-numbers\n" +
-            "      key: ${{ runner.os }}-primes\n" +
-            "    source: .github/workflows/ci.yml:12\n" +
-            "  - step: Run tests\n" +
-            "    id: test\n" +
-            "    run: |\n" +
-            "      echo starting\n" +
-            "      npm test\n" +
-            "    if: ${{ github.event_name == 'push' }}\n" +
-            "    env:\n" +
-            "      NODE_ENV: production\n" +
-            "    shell: bash\n" +
-            "    working-directory: ./api\n" +
-            "    source: .github/workflows/ci.yml:18\n" +
-            "  - step: npm ci\n" +
-            "    run: npm ci\n" +
-            "    source: .github/workflows/ci.yml:28\n" +
-            "\n" +
-            "post:\n" +
-            "  - step: Post actions/cache@v5\n" +
-            "    action: actions/cache@v5\n" +
-            "  - step: Post actions/checkout@v4\n" +
-            "    action: actions/checkout@v4\n" +
-            "\n" +
-            "cleanup:\n" +
-            "  - step: Complete job\n";
-
-        private static List<JobExecutionViewEntry> WorkedExampleEntries()
-        {
-            return new List<JobExecutionViewEntry>
-            {
-                new JobExecutionViewEntry(JobExecutionPhase.Pre, "Pre actions/checkout@v4", uses: "actions/checkout@v4"),
-                new JobExecutionViewEntry(JobExecutionPhase.Pre, "Pre actions/cache@v5", uses: "actions/cache@v5"),
-                new JobExecutionViewEntry(JobExecutionPhase.Main, "actions/checkout@v4", uses: "actions/checkout@v4", sourcePath: ".github/workflows/ci.yml", sourceLine: 10),
-                new JobExecutionViewEntry(
-                    JobExecutionPhase.Main,
-                    "Cache Primes",
-                    uses: "actions/cache@v5",
-                    id: "cache-primes",
-                    withYaml: "      path: prime-numbers\n      key: ${{ runner.os }}-primes",
-                    sourcePath: ".github/workflows/ci.yml",
-                    sourceLine: 12),
-                new JobExecutionViewEntry(
-                    JobExecutionPhase.Main,
-                    "Run tests",
-                    run: "echo starting\nnpm test",
-                    id: "test",
-                    @if: "${{ github.event_name == 'push' }}",
-                    envYaml: "      NODE_ENV: production",
-                    shell: "bash",
-                    workingDirectory: "./api",
-                    sourcePath: ".github/workflows/ci.yml",
-                    sourceLine: 18),
-                new JobExecutionViewEntry(JobExecutionPhase.Main, "npm ci", run: "npm ci", sourcePath: ".github/workflows/ci.yml", sourceLine: 28),
-                new JobExecutionViewEntry(JobExecutionPhase.Post, "Post actions/cache@v5", uses: "actions/cache@v5"),
-                new JobExecutionViewEntry(JobExecutionPhase.Post, "Post actions/checkout@v4", uses: "actions/checkout@v4"),
-            };
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_MatchesDesignDocWorkedExample()
-        {
-            var entries = WorkedExampleEntries();
-
-            var result = JobExecutionViewRenderer.Render("build", entries);
-
-            Assert.Equal(ExpectedWorkedExampleYaml, result.Yaml);
-            Assert.Equal(8, result.EntryStartLines.Count);
-            var lines = result.Yaml.Split('\n');
-            for (int i = 0; i < entries.Count; i++)
-            {
-                Assert.StartsWith("  - step: ", lines[result.EntryStartLines[i] - 1]);
-                Assert.Contains(entries[i].DisplayName, lines[result.EntryStartLines[i] - 1]);
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_AlwaysEmitsSetupAndCleanup()
-        {
-            var result = JobExecutionViewRenderer.Render("job-1", new List<JobExecutionViewEntry>());
-
-            const string expected =
-                "# Job: job-1\n" +
-                "# Runner execution plan — read-only.\n" +
-                "\n" +
-                "setup:\n" +
-                "  - step: Setup job\n" +
-                "\n" +
-                "cleanup:\n" +
-                "  - step: Complete job\n";
-            Assert.Equal(expected, result.Yaml);
-            Assert.Empty(result.EntryStartLines);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_OmitsEmptyOptionalSections()
-        {
-            // Only a Main entry — pre:/post: must not appear.
-            var result = JobExecutionViewRenderer.Render("j", new[]
-            {
-                new JobExecutionViewEntry(JobExecutionPhase.Main, "echo", run: "echo hello"),
-            });
-
-            Assert.Contains("setup:\n", result.Yaml);
-            Assert.Contains("main:\n", result.Yaml);
-            Assert.Contains("cleanup:\n", result.Yaml);
-            Assert.DoesNotContain("\npre:\n", result.Yaml);
-            Assert.DoesNotContain("\npost:\n", result.Yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_EmitsPhaseSectionsInFixedOrder()
-        {
-            // Input order [Post, Pre, Main] should still render as setup → pre → main → post → cleanup.
-            var entries = new[]
-            {
-                new JobExecutionViewEntry(JobExecutionPhase.Post, "post-a", uses: "a/b@v1"),
-                new JobExecutionViewEntry(JobExecutionPhase.Pre, "pre-a", uses: "a/b@v1"),
-                new JobExecutionViewEntry(JobExecutionPhase.Main, "main-a", uses: "a/b@v1"),
-            };
-
-            var result = JobExecutionViewRenderer.Render("j", entries);
-            string yaml = result.Yaml;
-
-            int setupIdx = yaml.IndexOf("setup:\n", StringComparison.Ordinal);
-            int preIdx = yaml.IndexOf("\npre:\n", StringComparison.Ordinal);
-            int mainIdx = yaml.IndexOf("\nmain:\n", StringComparison.Ordinal);
-            int postIdx = yaml.IndexOf("\npost:\n", StringComparison.Ordinal);
-            int cleanupIdx = yaml.IndexOf("\ncleanup:\n", StringComparison.Ordinal);
-            Assert.True(setupIdx >= 0 && preIdx > setupIdx && mainIdx > preIdx && postIdx > mainIdx && cleanupIdx > postIdx,
-                $"section ordering wrong: setup={setupIdx} pre={preIdx} main={mainIdx} post={postIdx} cleanup={cleanupIdx}");
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_StartLinesAlignWithInputOrder()
-        {
-            // Input order is [Pre, Main, Post]; output order is also pre/main/post,
-            // but startLines must be indexed by INPUT position, not by section.
-            var entries = new[]
-            {
-                new JobExecutionViewEntry(JobExecutionPhase.Pre, "pre-x", uses: "x/y@v1"),     // index 0
-                new JobExecutionViewEntry(JobExecutionPhase.Main, "main-x", uses: "x/y@v1"),    // index 1
-                new JobExecutionViewEntry(JobExecutionPhase.Post, "post-x", uses: "x/y@v1"),    // index 2
-            };
-
-            var result = JobExecutionViewRenderer.Render("j", entries);
-            var lines = result.Yaml.Split('\n');
-
-            Assert.StartsWith("  - step: pre-x", lines[result.EntryStartLines[0] - 1]);
-            Assert.StartsWith("  - step: main-x", lines[result.EntryStartLines[1] - 1]);
-            Assert.StartsWith("  - step: post-x", lines[result.EntryStartLines[2] - 1]);
-            // And input-order ordering of start lines is strictly increasing
-            // when phases are in declaration order matching the section order.
-            Assert.True(result.EntryStartLines[0] < result.EntryStartLines[1]);
-            Assert.True(result.EntryStartLines[1] < result.EntryStartLines[2]);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_StartLinesFollowInputOrderEvenWhenPhasesAreInterleaved()
-        {
-            // Input order is [Main A, Pre B, Main C]: pre section will render
-            // first (Pre B) and main second (Main A then Main C). startLines
-            // must still be indexed by input order.
-            var entries = new[]
-            {
-                new JobExecutionViewEntry(JobExecutionPhase.Main, "main-a", uses: "a@v1"),  // index 0 — renders in main section
-                new JobExecutionViewEntry(JobExecutionPhase.Pre, "pre-b", uses: "b@v1"),    // index 1 — renders in pre section
-                new JobExecutionViewEntry(JobExecutionPhase.Main, "main-c", uses: "c@v1"),  // index 2 — renders in main section
-            };
-
-            var result = JobExecutionViewRenderer.Render("j", entries);
-            var lines = result.Yaml.Split('\n');
-
-            Assert.StartsWith("  - step: main-a", lines[result.EntryStartLines[0] - 1]);
-            Assert.StartsWith("  - step: pre-b", lines[result.EntryStartLines[1] - 1]);
-            Assert.StartsWith("  - step: main-c", lines[result.EntryStartLines[2] - 1]);
-            // The pre section comes before main: input-index-1 entry's line is
-            // before input-index-0 entry's line.
-            Assert.True(result.EntryStartLines[1] < result.EntryStartLines[0]);
-            Assert.True(result.EntryStartLines[0] < result.EntryStartLines[2]);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_EntryStartLinesPointAtStepKeys()
-        {
-            var entries = WorkedExampleEntries();
-            var result = JobExecutionViewRenderer.Render("build", entries);
-            var lines = result.Yaml.Split('\n');
-
-            for (int i = 0; i < result.EntryStartLines.Count; i++)
-            {
-                int oneBased = result.EntryStartLines[i];
-                Assert.True(oneBased >= 1 && oneBased <= lines.Length, $"start line {oneBased} out of range");
-                Assert.StartsWith("  - step: ", lines[oneBased - 1]);
-            }
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_EntryStartLinesExcludeSetupAndCleanup()
-        {
-            var entries = WorkedExampleEntries();
-            var result = JobExecutionViewRenderer.Render("build", entries);
-            var lines = result.Yaml.Split('\n');
-
-            int setupLine = -1, cleanupLine = -1;
-            for (int i = 0; i < lines.Length; i++)
-            {
-                if (lines[i] == "  - step: Setup job") setupLine = i + 1;
-                if (lines[i] == "  - step: Complete job") cleanupLine = i + 1;
-            }
-            Assert.True(setupLine > 0 && cleanupLine > 0, "Setup/Cleanup lines must exist");
-            Assert.DoesNotContain(setupLine, result.EntryStartLines);
-            Assert.DoesNotContain(cleanupLine, result.EntryStartLines);
-        }
-
-        [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")]
-        public void Render_QuotesSpecialChars(string displayName)
-        {
-            // Round-trip the rendered YAML through YamlDotNet's deserializer
-            // and assert the parsed step's display name matches the input.
-            // This decouples the test from any specific quoting style.
-            var entry = new JobExecutionViewEntry(JobExecutionPhase.Main, displayName);
-            var result = JobExecutionViewRenderer.Render("j", new[] { entry });
-
-            var deserializer = new YamlDotNet.Serialization.DeserializerBuilder().Build();
-            var doc = deserializer.Deserialize<Dictionary<string, List<Dictionary<string, object>>>>(result.Yaml);
-            Assert.NotNull(doc);
-            Assert.True(doc.ContainsKey("main"), "rendered YAML missing top-level 'main' key");
-            var mainSteps = doc["main"];
-            Assert.Single(mainSteps);
-            Assert.Equal(displayName, mainSteps[0]["step"] as string);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_EmitsSourceAnnotationForMainStep()
-        {
-            var entry = new JobExecutionViewEntry(
-                JobExecutionPhase.Main,
-                "npm ci",
-                run: "npm ci",
-                sourcePath: ".github/workflows/ci.yml",
-                sourceLine: 42);
-
-            var result = JobExecutionViewRenderer.Render("j", new[] { entry });
-
-            Assert.Contains("    source: .github/workflows/ci.yml:42\n", result.Yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_OmitsSourceAnnotationForPreAndPost()
-        {
-            var pre = new JobExecutionViewEntry(
-                JobExecutionPhase.Pre,
-                "Pre actions/checkout@v4",
-                uses: "actions/checkout@v4",
-                sourcePath: ".github/workflows/ci.yml",
-                sourceLine: 9);
-            var post = new JobExecutionViewEntry(
-                JobExecutionPhase.Post,
-                "Post actions/checkout@v4",
-                uses: "actions/checkout@v4",
-                sourcePath: ".github/workflows/ci.yml",
-                sourceLine: 9);
-
-            var result = JobExecutionViewRenderer.Render("j", new[] { pre, post });
-
-            Assert.DoesNotContain("source:", result.Yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_EmitsMultilineRunAsBlockScalar()
-        {
-            var entry = new JobExecutionViewEntry(
-                JobExecutionPhase.Main,
-                "multi",
-                run: "echo a\necho b\necho c");
-
-            var result = JobExecutionViewRenderer.Render("j", new[] { entry });
-
-            Assert.Contains("    run: |\n", result.Yaml);
-            Assert.Contains("      echo a\n", result.Yaml);
-            Assert.Contains("      echo b\n", result.Yaml);
-            Assert.Contains("      echo c\n", result.Yaml);
-            Assert.DoesNotContain("truncated", result.Yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_EmitsAllUserAuthoredParamsForActionStep()
-        {
-            var entry = new JobExecutionViewEntry(
-                JobExecutionPhase.Main,
-                "Run action",
-                uses: "actions/cache@v5",
-                id: "cache-primes",
-                @if: "${{ github.event_name == 'push' }}",
-                continueOnError: "true",
-                timeoutMinutes: "10",
-                envYaml: "      NODE_ENV: production",
-                withYaml: "      path: prime-numbers\n      key: ${{ runner.os }}-primes",
-                sourcePath: "ci.yml",
-                sourceLine: 5);
-
-            var result = JobExecutionViewRenderer.Render("j", new[] { entry });
-
-            Assert.Contains("    id: cache-primes\n", result.Yaml);
-            Assert.Contains("    uses: actions/cache@v5\n", result.Yaml);
-            Assert.Contains("    continue-on-error: true\n", result.Yaml);
-            Assert.Contains("    timeout-minutes: 10\n", result.Yaml);
-            Assert.Contains("    env:\n      NODE_ENV: production\n", result.Yaml);
-            Assert.Contains("    with:\n      path: prime-numbers\n      key: ${{ runner.os }}-primes\n", result.Yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_EmitsRunStepWithShellAndWorkingDirectory()
-        {
-            var entry = new JobExecutionViewEntry(
-                JobExecutionPhase.Main,
-                "Run tests",
-                run: "echo starting\nnpm test",
-                id: "test",
-                shell: "bash",
-                workingDirectory: "./api");
-
-            var result = JobExecutionViewRenderer.Render("j", new[] { entry });
-
-            Assert.Contains("    run: |\n      echo starting\n      npm test\n", result.Yaml);
-            Assert.Contains("    shell: bash\n", result.Yaml);
-            Assert.Contains("    working-directory: ./api\n", result.Yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_PreservesExpressionsInRenderedYaml()
-        {
-            var entry = new JobExecutionViewEntry(
-                JobExecutionPhase.Main,
-                "Cache",
-                uses: "actions/cache@v5",
-                withYaml: "      key: ${{ runner.os }}-primes");
-
-            var result = JobExecutionViewRenderer.Render("j", new[] { entry });
-
-            // Expressions render exactly as authored — no evaluation.
-            Assert.Contains("${{ runner.os }}-primes", result.Yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_PrePostStepsRemainMinimal()
-        {
-            // Even if a pre/post entry carries user-param fields (it shouldn't
-            // in production, but the renderer must defensively drop them),
-            // only step: + action: render for these phases.
-            var pre = new JobExecutionViewEntry(
-                JobExecutionPhase.Pre,
-                "Pre actions/cache@v5",
-                uses: "actions/cache@v5",
-                id: "should-not-appear",
-                envYaml: "      X: y",
-                withYaml: "      key: nope");
-            var post = new JobExecutionViewEntry(
-                JobExecutionPhase.Post,
-                "Post actions/cache@v5",
-                uses: "actions/cache@v5",
-                id: "should-not-appear",
-                envYaml: "      X: y");
-
-            var result = JobExecutionViewRenderer.Render("j", new[] { pre, post });
-
-            Assert.DoesNotContain("id:", result.Yaml);
-            Assert.DoesNotContain("env:", result.Yaml);
-            Assert.DoesNotContain("with:", result.Yaml);
-            Assert.DoesNotContain("should-not-appear", result.Yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_FieldOrderIsStable()
-        {
-            var entry = new JobExecutionViewEntry(
-                JobExecutionPhase.Main,
-                "Everything",
-                uses: "actions/cache@v5",
-                id: "x",
-                @if: "always()",
-                continueOnError: "false",
-                timeoutMinutes: "5",
-                envYaml: "      A: 1",
-                withYaml: "      key: k",
-                sourcePath: "ci.yml",
-                sourceLine: 1);
-
-            var result = JobExecutionViewRenderer.Render("j", new[] { entry });
-            var y = result.Yaml;
-            int iStep = y.IndexOf("    - step: ", StringComparison.Ordinal) >= 0
-                ? y.IndexOf("- step:", StringComparison.Ordinal) : y.IndexOf("- step:", StringComparison.Ordinal);
-            int iId = y.IndexOf("    id:", StringComparison.Ordinal);
-            int iUses = y.IndexOf("    uses:", StringComparison.Ordinal);
-            int iIf = y.IndexOf("    if:", StringComparison.Ordinal);
-            int iCoe = y.IndexOf("    continue-on-error:", StringComparison.Ordinal);
-            int iTm = y.IndexOf("    timeout-minutes:", StringComparison.Ordinal);
-            int iEnv = y.IndexOf("    env:", StringComparison.Ordinal);
-            int iWith = y.IndexOf("    with:", StringComparison.Ordinal);
-            int iSrc = y.IndexOf("    source:", StringComparison.Ordinal);
-            Assert.True(iId < iUses && iUses < iIf && iIf < iCoe && iCoe < iTm && iTm < iEnv && iEnv < iWith && iWith < iSrc,
-                $"order wrong: id={iId} uses={iUses} if={iIf} coe={iCoe} tm={iTm} env={iEnv} with={iWith} src={iSrc}");
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_OmitsEmptyOptionalFields()
-        {
-            var entry = new JobExecutionViewEntry(
-                JobExecutionPhase.Main,
-                "bare",
-                uses: "a/b@v1");
-
-            var result = JobExecutionViewRenderer.Render("j", new[] { entry });
-            Assert.DoesNotContain("    id:", result.Yaml);
-            Assert.DoesNotContain("    if:", result.Yaml);
-            Assert.DoesNotContain("    continue-on-error:", result.Yaml);
-            Assert.DoesNotContain("    timeout-minutes:", result.Yaml);
-            Assert.DoesNotContain("    env:", result.Yaml);
-            Assert.DoesNotContain("    with:", result.Yaml);
-            Assert.DoesNotContain("    shell:", result.Yaml);
-            Assert.DoesNotContain("    working-directory:", result.Yaml);
-            Assert.DoesNotContain("    source:", result.Yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_HandlesEmptyEntries()
-        {
-            var result = JobExecutionViewRenderer.Render("j", new List<JobExecutionViewEntry>());
-
-            Assert.Empty(result.EntryStartLines);
-            Assert.Contains("  - step: Setup job\n", result.Yaml);
-            Assert.Contains("  - step: Complete job\n", result.Yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_NoPerEntryPhaseField()
-        {
-            // The phase: <value> per-entry field is gone — the section
-            // header is the phase indicator. Guard against accidental
-            // regressions.
-            var result = JobExecutionViewRenderer.Render("build", WorkedExampleEntries());
-            Assert.DoesNotContain("phase:", result.Yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_ThrowsOnNullJobId()
-        {
-            Assert.Throws<ArgumentException>(
-                () => JobExecutionViewRenderer.Render(null, new List<JobExecutionViewEntry>()));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_ThrowsOnWhitespaceJobId()
-        {
-            Assert.Throws<ArgumentException>(
-                () => JobExecutionViewRenderer.Render("   ", new List<JobExecutionViewEntry>()));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_ThrowsOnNullEntries()
-        {
-            Assert.Throws<ArgumentNullException>(
-                () => JobExecutionViewRenderer.Render("j", null));
-        }
-
-        [Theory]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        [InlineData(null, 1)]
-        [InlineData("", 1)]
-        [InlineData("   ", 1)]
-        public void Entry_Constructor_RejectsBadDisplayName(string displayName, int sourceLine)
-        {
-            Assert.Throws<ArgumentException>(
-                () => new JobExecutionViewEntry(JobExecutionPhase.Main, displayName, sourceLine: sourceLine));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Entry_Constructor_RejectsZeroLineWhenSourcePathSet()
-        {
-            Assert.Throws<ArgumentException>(
-                () => new JobExecutionViewEntry(
-                    JobExecutionPhase.Main,
-                    "ok",
-                    sourcePath: "ci.yml",
-                    sourceLine: 0));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_EmitsSkippedAnnotationForMarkedEntry()
-        {
-            var entry = new JobExecutionViewEntry(JobExecutionPhase.Post, "Post X", uses: "actions/x@v1");
-            entry.IsSkipped = true;
-
-            var result = JobExecutionViewRenderer.Render("j", new[] { entry });
-
-            // Annotation is inline on the `- step:` line so subsequent
-            // entry line numbers stay stable.
-            Assert.Contains("- step: Post X  # (skipped — main step did not execute)\n", result.Yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Render_SkippedAnnotation_DoesNotShiftSubsequentLines()
-        {
-            var skipped = new JobExecutionViewEntry(JobExecutionPhase.Post, "Post A", uses: "actions/a@v1");
-            var following = new JobExecutionViewEntry(JobExecutionPhase.Post, "Post B", uses: "actions/b@v1");
-
-            var unmarked = JobExecutionViewRenderer.Render("j", new[] { skipped, following });
-            skipped.IsSkipped = true;
-            var marked = JobExecutionViewRenderer.Render("j", new[] { skipped, following });
-
-            // Following entry's start line must not move when the prior
-            // entry gets an inline skipped annotation.
-            Assert.Equal(unmarked.EntryStartLines[1], marked.EntryStartLines[1]);
-        }
-    }
-}

src/Test/L0/Worker/JobExtensionL0.cs

@@ -141,7 +141,6 @@ namespace GitHub.Runner.Common.Tests.Worker
             hc.SetSingleton(_diagnosticLogManager.Object);
             hc.SetSingleton(_jobHookProvider.Object);
             hc.SetSingleton(_snapshotOperationProvider.Object);
-            hc.SetSingleton(new Mock<IDapDebugger>().Object);
             hc.EnqueueInstance<IPagingLogger>(_logger.Object); // JobExecutionContext
             hc.EnqueueInstance<IPagingLogger>(_logger.Object); // job start hook
             hc.EnqueueInstance<IPagingLogger>(_logger.Object); // Initial Job

src/Test/L0/Worker/JobRunnerL0.cs

@@ -1,6 +1,5 @@
 using GitHub.DistributedTask.WebApi;
 using GitHub.Runner.Worker;
-using GitHub.Runner.Worker.Dap;
 using Moq;
 using System;
 using System.Collections.Generic;
@@ -84,7 +83,6 @@ namespace GitHub.Runner.Common.Tests.Worker
             hc.SetSingleton(_extensions.Object);
             hc.SetSingleton(_temp.Object);
             hc.SetSingleton(_diagnosticLogManager.Object);
-            hc.SetSingleton(new Mock<IDapDebugger>().Object);
             hc.EnqueueInstance<IExecutionContext>(_jobEc);
             hc.EnqueueInstance<IPagingLogger>(_logger.Object);
             hc.EnqueueInstance<IJobExtension>(_jobExtension.Object);
@@ -177,29 +175,5 @@ namespace GitHub.Runner.Common.Tests.Worker
                 Assert.Equal(TaskResult.Succeeded, _jobEc.Result);
             }
         }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public async Task DebuggerDisabled_DoesNotInvokeDapDebugger()
-        {
-            using (TestHostContext hc = CreateTestContext())
-            {
-                // Override the lenient IDapDebugger singleton from CreateTestContext
-                // with a strict mock. If the containment guard fails, the production
-                // code will call OnJobStepsInitializedAsync and the strict mock will throw.
-                var dapMock = new Mock<IDapDebugger>(MockBehavior.Strict);
-                hc.SetSingleton(dapMock.Object);
-
-                var message = GetMessage();
-                // EnableDebugger defaults to false on AgentJobRequestMessage.
-                Assert.False(message.EnableDebugger);
-
-                await _jobRunner.RunAsync(message, _tokenSource.Token);
-
-                Assert.Equal(TaskResult.Succeeded, _jobEc.Result);
-                dapMock.VerifyNoOtherCalls();
-            }
-        }
     }
 }

src/Test/L0/Worker/StepEntryTranslatorL0.cs

@@ -1,425 +0,0 @@
-using System;
-using System.Collections.Generic;
-using GitHub.DistributedTask.ObjectTemplating.Tokens;
-using GitHub.DistributedTask.Pipelines;
-using GitHub.Runner.Worker;
-using GitHub.Runner.Worker.Dap;
-using Moq;
-using Xunit;
-
-namespace GitHub.Runner.Common.Tests.Worker
-{
-    public sealed class StepEntryTranslatorL0
-    {
-        private static StringToken Str(string s) => new(null, null, null, s);
-
-        private static MappingToken Map(params (string Key, TemplateToken Value)[] pairs)
-        {
-            var m = new MappingToken(null, null, null);
-            foreach (var (k, v) in pairs)
-            {
-                m.Add(Str(k), v);
-            }
-            return m;
-        }
-
-        private static Mock<IActionRunner> NewActionRunnerMock(
-            ActionRunStage stage,
-            string displayName,
-            ActionStepDefinitionReference reference,
-            ActionStep actionOverride = null)
-        {
-            var mock = new Mock<IActionRunner>();
-            mock.SetupGet(x => x.Stage).Returns(stage);
-            mock.SetupGet(x => x.DisplayName).Returns(displayName);
-            mock.SetupGet(x => x.Action).Returns(actionOverride ?? new ActionStep
-            {
-                Reference = reference,
-            });
-            return mock;
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Translate_NullStep_Throws()
-        {
-            Assert.Throws<ArgumentNullException>(() =>
-                StepEntryTranslator.TryTranslate(null));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Translate_JobExtensionRunner_ReturnsNull()
-        {
-            var step = new JobExtensionRunner(
-                runAsync: (_, __) => System.Threading.Tasks.Task.CompletedTask,
-                condition: null,
-                displayName: "Set up job",
-                data: null);
-
-            Assert.Null(StepEntryTranslator.TryTranslate(step));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Translate_OtherIStepType_ReturnsNull()
-        {
-            var mock = new Mock<IStep>();
-            mock.SetupGet(x => x.DisplayName).Returns("custom");
-
-            Assert.Null(StepEntryTranslator.TryTranslate(mock.Object));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Translate_ActionRunnerPre_ReturnsPreEntry()
-        {
-            var reference = new RepositoryPathReference
-            {
-                Name = "actions/checkout",
-                Ref = "v4",
-            };
-            var mock = NewActionRunnerMock(ActionRunStage.Pre, "Pre Run actions/checkout@v4", reference);
-
-            var entry = StepEntryTranslator.TryTranslate(mock.Object);
-
-            Assert.NotNull(entry);
-            Assert.Equal(JobExecutionPhase.Pre, entry.Phase);
-            Assert.Equal("Pre Run actions/checkout@v4", entry.DisplayName);
-            Assert.Equal("actions/checkout@v4", entry.Uses);
-            Assert.Null(entry.Run);
-            Assert.Null(entry.SourcePath);
-            Assert.Equal(0, entry.SourceLine);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Translate_ActionRunnerMain_ReturnsMainEntryWithUses()
-        {
-            var reference = new RepositoryPathReference
-            {
-                Name = "actions/setup-node",
-                Path = "subdir",
-                Ref = "v3",
-            };
-            var mock = NewActionRunnerMock(ActionRunStage.Main, "Run actions/setup-node@v3", reference);
-
-            var entry = StepEntryTranslator.TryTranslate(mock.Object);
-
-            Assert.NotNull(entry);
-            Assert.Equal(JobExecutionPhase.Main, entry.Phase);
-            Assert.Equal("actions/setup-node/subdir@v3", entry.Uses);
-            Assert.Null(entry.Run);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Translate_ActionRunnerMain_ScriptReference_LeavesUsesNull()
-        {
-            var mock = NewActionRunnerMock(ActionRunStage.Main, "Run echo hi", new ScriptReference());
-
-            var entry = StepEntryTranslator.TryTranslate(mock.Object);
-
-            Assert.NotNull(entry);
-            Assert.Equal(JobExecutionPhase.Main, entry.Phase);
-            Assert.Null(entry.Uses);
-            Assert.Null(entry.Run);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Translate_ActionRunnerMain_ContainerReference_UsesImage()
-        {
-            var reference = new ContainerRegistryReference { Image = "alpine:3.18" };
-            var mock = NewActionRunnerMock(ActionRunStage.Main, "Run alpine", reference);
-
-            var entry = StepEntryTranslator.TryTranslate(mock.Object);
-
-            Assert.NotNull(entry);
-            Assert.Equal("alpine:3.18", entry.Uses);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Translate_ActionRunnerPost_ReturnsPostEntry()
-        {
-            var reference = new RepositoryPathReference { Name = "actions/cache", Ref = "v3" };
-            var mock = NewActionRunnerMock(ActionRunStage.Post, "Post Run actions/cache@v3", reference);
-
-            var entry = StepEntryTranslator.TryTranslate(mock.Object);
-
-            Assert.NotNull(entry);
-            Assert.Equal(JobExecutionPhase.Post, entry.Phase);
-            Assert.Equal("Post Run actions/cache@v3", entry.DisplayName);
-            Assert.Equal("actions/cache@v3", entry.Uses);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Translate_ActionRunner_NullAction_LeavesUsesNull()
-        {
-            var mock = new Mock<IActionRunner>();
-            mock.SetupGet(x => x.Stage).Returns(ActionRunStage.Main);
-            mock.SetupGet(x => x.DisplayName).Returns("anonymous");
-            mock.SetupGet(x => x.Action).Returns((ActionStep)null);
-
-            var entry = StepEntryTranslator.TryTranslate(mock.Object);
-
-            Assert.NotNull(entry);
-            Assert.Equal("anonymous", entry.DisplayName);
-            Assert.Null(entry.Uses);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Translate_ActionStep_ExtractsWith()
-        {
-            var reference = new RepositoryPathReference { Name = "actions/cache", Ref = "v5" };
-            var action = new ActionStep
-            {
-                Reference = reference,
-                Inputs = Map(("path", Str("prime-numbers")), ("key", Str("k"))),
-            };
-            var mock = NewActionRunnerMock(ActionRunStage.Main, "Cache", reference, action);
-
-            var entry = StepEntryTranslator.TryTranslate(mock.Object);
-
-            Assert.NotNull(entry);
-            Assert.NotNull(entry.WithYaml);
-            Assert.Contains("path: prime-numbers", entry.WithYaml);
-            Assert.Contains("key: k", entry.WithYaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Translate_ActionStep_PreservesExpressionInWith()
-        {
-            var reference = new RepositoryPathReference { Name = "actions/cache", Ref = "v5" };
-            var action = new ActionStep
-            {
-                Reference = reference,
-                Inputs = Map(("key", Str("${{ runner.os }}-primes"))),
-            };
-            var mock = NewActionRunnerMock(ActionRunStage.Main, "Cache", reference, action);
-
-            var entry = StepEntryTranslator.TryTranslate(mock.Object);
-
-            Assert.NotNull(entry);
-            Assert.Contains("${{ runner.os }}-primes", entry.WithYaml);
-            Assert.DoesNotContain("Linux", entry.WithYaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Translate_RunStep_ExtractsScript()
-        {
-            var action = new ActionStep
-            {
-                Reference = new ScriptReference(),
-                Inputs = Map(("script", Str("echo hi"))),
-            };
-            var mock = NewActionRunnerMock(ActionRunStage.Main, "Run echo", new ScriptReference(), action);
-
-            var entry = StepEntryTranslator.TryTranslate(mock.Object);
-
-            Assert.NotNull(entry);
-            Assert.Null(entry.Uses);
-            Assert.Equal("echo hi", entry.Run);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Translate_RunStep_ExtractsShellAndWorkingDirectory()
-        {
-            var action = new ActionStep
-            {
-                Reference = new ScriptReference(),
-                Inputs = Map(
-                    ("script", Str("npm test")),
-                    ("shell", Str("bash")),
-                    ("working-directory", Str("./api"))),
-            };
-            var mock = NewActionRunnerMock(ActionRunStage.Main, "Run", new ScriptReference(), action);
-
-            var entry = StepEntryTranslator.TryTranslate(mock.Object);
-
-            Assert.NotNull(entry);
-            Assert.Equal("npm test", entry.Run);
-            Assert.Equal("bash", entry.Shell);
-            Assert.Equal("./api", entry.WorkingDirectory);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Translate_ActionStep_FiltersRunStepKeysFromWith()
-        {
-            // Defensive: an action step's Inputs should not contain
-            // run-step internal keys, but if it did, they must not
-            // surface in the with: rendering.
-            var reference = new RepositoryPathReference { Name = "a/b", Ref = "v1" };
-            var action = new ActionStep
-            {
-                Reference = reference,
-                Inputs = Map(
-                    ("mode", Str("ci")),
-                    ("script", Str("leak")),
-                    ("shell", Str("leak")),
-                    ("working-directory", Str("leak"))),
-            };
-            var mock = NewActionRunnerMock(ActionRunStage.Main, "Run", reference, action);
-
-            var entry = StepEntryTranslator.TryTranslate(mock.Object);
-
-            Assert.NotNull(entry);
-            Assert.NotNull(entry.WithYaml);
-            Assert.Contains("mode: ci", entry.WithYaml);
-            Assert.DoesNotContain("leak", entry.WithYaml);
-            Assert.DoesNotContain("script", entry.WithYaml);
-            Assert.DoesNotContain("shell", entry.WithYaml);
-            Assert.DoesNotContain("working-directory", entry.WithYaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Translate_ActionStep_OmitsEmptyEnv()
-        {
-            var reference = new RepositoryPathReference { Name = "a/b", Ref = "v1" };
-            var action = new ActionStep
-            {
-                Reference = reference,
-                Environment = new MappingToken(null, null, null),
-            };
-            var mock = NewActionRunnerMock(ActionRunStage.Main, "Run", reference, action);
-
-            var entry = StepEntryTranslator.TryTranslate(mock.Object);
-
-            Assert.NotNull(entry);
-            Assert.Null(entry.EnvYaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Translate_ActionStep_ExtractsEnv()
-        {
-            var reference = new RepositoryPathReference { Name = "a/b", Ref = "v1" };
-            var action = new ActionStep
-            {
-                Reference = reference,
-                Environment = Map(("NODE_ENV", Str("production"))),
-            };
-            var mock = NewActionRunnerMock(ActionRunStage.Main, "Run", reference, action);
-
-            var entry = StepEntryTranslator.TryTranslate(mock.Object);
-
-            Assert.NotNull(entry);
-            Assert.NotNull(entry.EnvYaml);
-            Assert.Contains("NODE_ENV: production", entry.EnvYaml);
-        }
-
-        [Theory]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        [InlineData(null)]
-        [InlineData("")]
-        [InlineData("   ")]
-        [InlineData("__1")]
-        [InlineData("__123")]
-        public void Translate_FiltersAutoGeneratedId(string contextName)
-        {
-            var reference = new RepositoryPathReference { Name = "a/b", Ref = "v1" };
-            var action = new ActionStep
-            {
-                Reference = reference,
-                ContextName = contextName,
-            };
-            var mock = NewActionRunnerMock(ActionRunStage.Main, "Run", reference, action);
-
-            var entry = StepEntryTranslator.TryTranslate(mock.Object);
-
-            Assert.NotNull(entry);
-            Assert.Null(entry.Id);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Translate_PreservesUserId()
-        {
-            var reference = new RepositoryPathReference { Name = "a/b", Ref = "v1" };
-            var action = new ActionStep
-            {
-                Reference = reference,
-                ContextName = "cache-primes",
-            };
-            var mock = NewActionRunnerMock(ActionRunStage.Main, "Cache", reference, action);
-
-            var entry = StepEntryTranslator.TryTranslate(mock.Object);
-
-            Assert.NotNull(entry);
-            Assert.Equal("cache-primes", entry.Id);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Translate_ActionStep_ExtractsCondition()
-        {
-            var reference = new RepositoryPathReference { Name = "a/b", Ref = "v1" };
-            var action = new ActionStep
-            {
-                Reference = reference,
-                Condition = "always()",
-            };
-            var mock = NewActionRunnerMock(ActionRunStage.Main, "Run", reference, action);
-
-            var entry = StepEntryTranslator.TryTranslate(mock.Object);
-
-            Assert.NotNull(entry);
-            Assert.Equal("always()", entry.If);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Translate_PreEntry_OmitsUserParams()
-        {
-            // Pre entries stay minimal — they reference the same Action as
-            // Main, and duplicating params adds noise.
-            var reference = new RepositoryPathReference { Name = "a/b", Ref = "v1" };
-            var action = new ActionStep
-            {
-                Reference = reference,
-                ContextName = "user-id",
-                Condition = "always()",
-                Environment = Map(("X", Str("y"))),
-                Inputs = Map(("k", Str("v"))),
-            };
-            var mock = NewActionRunnerMock(ActionRunStage.Pre, "Pre a/b@v1", reference, action);
-
-            var entry = StepEntryTranslator.TryTranslate(mock.Object);
-
-            Assert.NotNull(entry);
-            Assert.Equal(JobExecutionPhase.Pre, entry.Phase);
-            Assert.Null(entry.Id);
-            Assert.Null(entry.If);
-            Assert.Null(entry.EnvYaml);
-            Assert.Null(entry.WithYaml);
-        }
-    }
-}

src/Test/L0/Worker/TemplateTokenYamlAdapterL0.cs

@@ -1,155 +0,0 @@
-using GitHub.DistributedTask.ObjectTemplating.Tokens;
-using GitHub.Runner.Worker.Dap;
-using Xunit;
-
-namespace GitHub.Runner.Common.Tests.Worker
-{
-    public sealed class TemplateTokenYamlAdapterL0
-    {
-        private static StringToken Str(string s) => new(null, null, null, s);
-        private static BooleanToken Bool(bool b) => new(null, null, null, b);
-        private static NumberToken Num(double n) => new(null, null, null, n);
-        private static BasicExpressionToken Expr(string s) => new(null, null, null, s);
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Serialize_StringScalar()
-        {
-            Assert.Equal("hello", TemplateTokenYamlAdapter.Serialize(Str("hello"), 0));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Serialize_BooleanScalar()
-        {
-            Assert.Equal("true", TemplateTokenYamlAdapter.Serialize(Bool(true), 0));
-            Assert.Equal("false", TemplateTokenYamlAdapter.Serialize(Bool(false), 0));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Serialize_NumberScalar()
-        {
-            Assert.Equal("10", TemplateTokenYamlAdapter.Serialize(Num(10), 0));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Serialize_NullToken_RendersAsNull()
-        {
-            Assert.Equal("null", TemplateTokenYamlAdapter.Serialize(null, 0));
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Serialize_PreservesBasicExpression()
-        {
-            var token = Expr("runner.os");
-            string yaml = TemplateTokenYamlAdapter.Serialize(token, 0);
-            Assert.Contains("${{ runner.os }}", yaml);
-            Assert.DoesNotContain("Linux", yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Serialize_PreservesCompositeExpressionInStringToken()
-        {
-            // Composite strings like `${{ runner.os }}-primes` are parsed
-            // as a StringToken whose value is exactly that literal. The
-            // adapter must round-trip the literal unchanged.
-            var token = Str("${{ runner.os }}-primes");
-            string yaml = TemplateTokenYamlAdapter.Serialize(token, 0);
-            Assert.Contains("${{ runner.os }}-primes", yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Serialize_NestedMapping()
-        {
-            var inner = new MappingToken(null, null, null);
-            inner.Add(Str("b"), Num(1));
-            inner.Add(Str("c"), Expr("x"));
-            var outer = new MappingToken(null, null, null);
-            outer.Add(Str("a"), inner);
-
-            string yaml = TemplateTokenYamlAdapter.Serialize(outer, 0);
-
-            Assert.Contains("a:", yaml);
-            Assert.Contains("b: 1", yaml);
-            Assert.Contains("c: ${{ x }}", yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Serialize_EmptyMapping()
-        {
-            var token = new MappingToken(null, null, null);
-            string yaml = TemplateTokenYamlAdapter.Serialize(token, 0);
-            Assert.Equal("{}", yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Serialize_EmptySequence()
-        {
-            var token = new SequenceToken(null, null, null);
-            string yaml = TemplateTokenYamlAdapter.Serialize(token, 0);
-            Assert.Equal("[]", yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Serialize_MultilineString_UsesBlockScalar()
-        {
-            var token = Str("line1\nline2\nline3");
-            string yaml = TemplateTokenYamlAdapter.Serialize(token, 0);
-            // Block-literal indicator `|` appears for multi-line scalars.
-            Assert.Contains("|", yaml);
-            Assert.Contains("line1", yaml);
-            Assert.Contains("line2", yaml);
-            Assert.Contains("line3", yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Serialize_IndentLevel_PrefixesNonEmptyLines()
-        {
-            var map = new MappingToken(null, null, null);
-            map.Add(Str("k1"), Str("v1"));
-            map.Add(Str("k2"), Str("v2"));
-
-            string yaml = TemplateTokenYamlAdapter.Serialize(map, indentSpaces: 4);
-
-            foreach (var line in yaml.Split('\n'))
-            {
-                if (line.Length > 0)
-                {
-                    Assert.StartsWith("    ", line);
-                }
-            }
-            Assert.Contains("k1: v1", yaml);
-            Assert.Contains("k2: v2", yaml);
-        }
-
-        [Fact]
-        [Trait("Level", "L0")]
-        [Trait("Category", "Worker")]
-        public void Serialize_NoTrailingNewline()
-        {
-            var token = Str("hello");
-            string yaml = TemplateTokenYamlAdapter.Serialize(token, 0);
-            Assert.False(yaml.EndsWith("\n"));
-        }
-    }
-}