Add DAP execution view coverage

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.gitignore

@@ -27,4 +27,5 @@ TestResults
 TestLogs
 .DS_Store
 .mono
-**/*.DotSettings.user
+**/*.DotSettings.user
+**/*.lscache

src/Misc/externals.sh

@@ -7,7 +7,7 @@ NODE_ALPINE_URL=https://github.com/actions/alpine_nodejs/releases/download
 # When you update Node versions you must also create a new release of alpine_nodejs at that updated version.
 # Follow the instructions here: https://github.com/actions/alpine_nodejs?tab=readme-ov-file#getting-started
 NODE20_VERSION="20.20.2"
-NODE24_VERSION="24.15.0"
+NODE24_VERSION="24.16.0"
 
 get_abs_path() {
   # exploits the fact that pwd will print abs path when no args

src/Runner.Common/Constants.cs

@@ -206,7 +206,7 @@ namespace GitHub.Runner.Common
                 public static readonly string Node20DeprecationUrl = "https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/";
 
                 // Node 20 migration dates (hardcoded fallbacks, can be overridden via job variables)
-                public static readonly string Node24DefaultDate = "June 2nd, 2026";
+                public static readonly string Node24DefaultDate = "June 16th, 2026";
                 public static readonly string Node20RemovalDate = "September 16th, 2026";
 
                 // Variable keys for server-overridable dates

src/Runner.Worker/Dap/DapDebugger.cs

@@ -16,6 +16,7 @@ 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
 {
@@ -27,6 +28,7 @@ namespace GitHub.Runner.Worker.Dap
         public string DisplayName { get; set; }
         public TaskResult? Result { get; set; }
         public int FrameId { get; set; }
+        public int? SourceLine { get; set; }
     }
 
     /// <summary>
@@ -54,6 +56,9 @@ namespace GitHub.Runner.Worker.Dap
         // Frame IDs for completed steps start at 1000
         private const int _completedFrameIdBase = 1000;
 
+        // Stable session-scoped source reference for the synthesized job step list.
+        private const int _jobStepsSourceReference = 1;
+
         private TcpListener _listener;
         private TcpClient _client;
         private NetworkStream _stream;
@@ -98,6 +103,8 @@ namespace GitHub.Runner.Worker.Dap
         // Track completed steps for stack trace
         private readonly List<CompletedStepInfo> _completedSteps = new List<CompletedStepInfo>();
         private int _nextCompletedFrameId = _completedFrameIdBase;
+        private JobExecutionView _jobStepsSource;
+        private bool _jobCompleted;
 
         // Client connection tracking for reconnection support
         private volatile bool _isClientConnected;
@@ -240,6 +247,179 @@ namespace GitHub.Runner.Worker.Dap
             }
         }
 
+        public Task OnJobStepsInitializedAsync(IEnumerable<IStep> steps, IEnumerable<IStep> initialPostSteps)
+        {
+            if (!IsActive)
+            {
+                return Task.CompletedTask;
+            }
+
+            try
+            {
+                IExecutionContext jobContext;
+                lock (_stateLock)
+                {
+                    if (_state != DapSessionState.Ready &&
+                        _state != DapSessionState.Paused &&
+                        _state != DapSessionState.Running)
+                    {
+                        return Task.CompletedTask;
+                    }
+
+                    jobContext = _jobContext;
+                }
+
+                var stepList = steps?.Where(step => step != null).ToList() ?? new List<IStep>();
+                var initialPostStepList = initialPostSteps?.Where(step => step != null).ToList() ?? new List<IStep>();
+                var jobId = jobContext?.GetGitHubContext("job");
+                var snapshot = new JobExecutionView(
+                    jobId,
+                    stepList,
+                    initialPostStepList,
+                    PredictPostSteps(jobContext, stepList, initialPostStepList));
+
+                lock (_stateLock)
+                {
+                    _jobStepsSource = snapshot;
+                    _jobCompleted = false;
+                }
+                Trace.Info("DAP job steps source initialized");
+            }
+            catch (Exception ex)
+            {
+                Trace.Warning("DAP OnJobStepsInitialized error.");
+                Trace.Error(ex);
+            }
+
+            return Task.CompletedTask;
+        }
+
+        public void OnPostStepRegistered(IStep step)
+        {
+            try
+            {
+                if (step is IActionRunner postRunner && postRunner.Action != null)
+                {
+                    JobExecutionView snapshot;
+                    lock (_stateLock)
+                    {
+                        snapshot = _jobStepsSource;
+                    }
+
+                    var line = snapshot?.TryClaimPredictedStep(MatchKeyFor(postRunner.Action.Id), step);
+                    if (line.HasValue)
+                    {
+                        Trace.Info($"DAP job steps source claimed predicted post step '{step.DisplayName}' at line {line.Value}.");
+                    }
+                    else
+                    {
+                        Trace.Info($"DAP job steps source had no predicted line for post step '{step.DisplayName}'.");
+                    }
+                }
+            }
+            catch (Exception ex)
+            {
+                Trace.Warning("DAP OnPostStepRegistered error.");
+                Trace.Error(ex);
+            }
+        }
+
+        private IReadOnlyList<JobExecutionView.PredictedPostStep> PredictPostSteps(
+            IExecutionContext jobContext,
+            IReadOnlyList<IStep> steps,
+            IReadOnlyList<IStep> initialPostSteps)
+        {
+            if (jobContext == null || steps == null || steps.Count == 0)
+            {
+                return Array.Empty<JobExecutionView.PredictedPostStep>();
+            }
+
+            IActionManager actionManager;
+            try
+            {
+                actionManager = HostContext.GetService<IActionManager>();
+            }
+            catch (Exception ex)
+            {
+                Trace.Info($"DAP post-step predictor skipped because IActionManager is unavailable ({ex.Message}).");
+                return Array.Empty<JobExecutionView.PredictedPostStep>();
+            }
+
+            var predictions = new List<JobExecutionView.PredictedPostStep>();
+            var seenActionIds = new HashSet<Guid>();
+            if (initialPostSteps != null)
+            {
+                foreach (var postStep in initialPostSteps)
+                {
+                    if (postStep is IActionRunner postRunner && postRunner.Action != null)
+                    {
+                        seenActionIds.Add(postRunner.Action.Id);
+                    }
+                }
+            }
+
+            foreach (var step in steps)
+            {
+                if (step is not IActionRunner runner ||
+                    runner.Stage == ActionRunStage.Post ||
+                    runner.Action == null)
+                {
+                    continue;
+                }
+
+                var action = runner.Action;
+                if (action.Reference is not Pipelines.RepositoryPathReference repoRef)
+                {
+                    continue;
+                }
+
+                if (!seenActionIds.Add(action.Id))
+                {
+                    continue;
+                }
+
+                Definition definition;
+                try
+                {
+                    definition = actionManager.LoadAction(jobContext, action);
+                }
+                catch (Exception ex)
+                {
+                    Trace.Info($"DAP post-step predictor could not load action '{repoRef.Name}' ({ex.Message}).");
+                    continue;
+                }
+
+                if (definition?.Data?.Execution?.HasPost != true)
+                {
+                    continue;
+                }
+
+                predictions.Add(new JobExecutionView.PredictedPostStep(
+                    GetPostDisplayName(runner),
+                    MatchKeyFor(action.Id)));
+            }
+
+            predictions.Reverse();
+            return predictions;
+        }
+
+        private static string GetPostDisplayName(IActionRunner runner)
+        {
+            var displayName = string.IsNullOrEmpty(runner.DisplayName) ? "step" : runner.DisplayName;
+            if (runner.Stage == ActionRunStage.Pre &&
+                displayName.StartsWith("Pre ", StringComparison.OrdinalIgnoreCase))
+            {
+                displayName = displayName.Substring("Pre ".Length);
+            }
+
+            return $"Post {displayName}";
+        }
+
+        private static string MatchKeyFor(Guid actionId)
+        {
+            return $"post:{actionId:N}";
+        }
+
         public async Task OnJobCompletedAsync()
         {
             if (_state != DapSessionState.NotStarted)
@@ -253,6 +433,11 @@ namespace GitHub.Runner.Worker.Dap
                         if (_jobContext != null)
                         {
                             Trace.Info("Job completed — pausing for inspection");
+                            lock (_stateLock)
+                            {
+                                _jobCompleted = true;
+                            }
+
                             SendStoppedEvent("completed", "Job completed — inspect variables before the session ends.");
 
                             await WaitForCommandAsync(_jobContext.CancellationToken);
@@ -359,6 +544,7 @@ namespace GitHub.Runner.Worker.Dap
                 {
                     _state = DapSessionState.Terminated;
                 }
+                _jobStepsSource = null;
             }
 
             _isClientConnected = false;
@@ -417,7 +603,8 @@ namespace GitHub.Runner.Worker.Dap
                     {
                         DisplayName = step.DisplayName,
                         Result = result,
-                        FrameId = _nextCompletedFrameId++
+                        FrameId = _nextCompletedFrameId++,
+                        SourceLine = _jobStepsSource?.TryGetLineForStep(step)
                     });
                 }
             }
@@ -468,6 +655,7 @@ namespace GitHub.Runner.Worker.Dap
                         "next" => HandleNext(request),
                         "setBreakpoints" => HandleSetBreakpoints(request),
                         "setExceptionBreakpoints" => HandleSetExceptionBreakpoints(request),
+                        "source" => HandleSource(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),
@@ -857,6 +1045,7 @@ namespace GitHub.Runner.Worker.Dap
         {
             bool pauseOnNextStep;
             CancellationToken cancellationToken;
+
             lock (_stateLock)
             {
                 if (_state != DapSessionState.Ready &&
@@ -868,6 +1057,7 @@ namespace GitHub.Runner.Worker.Dap
 
                 _currentStep = step;
                 _currentStepIndex = _completedSteps.Count;
+                _jobCompleted = false;
                 pauseOnNextStep = _pauseOnNextStep;
                 cancellationToken = _jobContext?.CancellationToken ?? CancellationToken.None;
             }
@@ -1050,29 +1240,46 @@ namespace GitHub.Runner.Worker.Dap
         private Response HandleStackTrace(Request request)
         {
             IStep currentStep;
-            int currentStepIndex;
             CompletedStepInfo[] completedSteps;
+            JobExecutionView jobStepsSource;
+            bool jobCompleted;
             lock (_stateLock)
             {
                 currentStep = _currentStep;
-                currentStepIndex = _currentStepIndex;
                 completedSteps = _completedSteps.ToArray();
+                jobStepsSource = _jobStepsSource;
+                jobCompleted = _jobCompleted;
             }
 
             var frames = new List<StackFrame>();
+            var source = jobStepsSource != null ? BuildJobStepsSource(jobStepsSource) : null;
 
             // Add current step as the top frame
-            if (currentStep != null)
+            if (jobCompleted && jobStepsSource != null)
+            {
+                frames.Add(new StackFrame
+                {
+                    Id = _currentFrameId,
+                    Name = "Complete job [completed]",
+                    Source = source,
+                    Line = jobStepsSource.CompleteJobLine,
+                    Column = 1,
+                    PresentationHint = "normal"
+                });
+            }
+            else if (currentStep != null)
             {
                 var resultIndicator = currentStep.ExecutionContext?.Result != null
                     ? $" [{currentStep.ExecutionContext.Result}]"
                     : " [running]";
+                var currentSourceLine = jobStepsSource?.TryGetLineForStep(currentStep);
 
                 frames.Add(new StackFrame
                 {
                     Id = _currentFrameId,
                     Name = MaskUserVisibleText($"{currentStep.DisplayName ?? "Current Step"}{resultIndicator}"),
-                    Line = currentStepIndex + 1,
+                    Source = currentSourceLine.HasValue ? source : null,
+                    Line = currentSourceLine ?? 0,
                     Column = 1,
                     PresentationHint = "normal"
                 });
@@ -1098,7 +1305,8 @@ namespace GitHub.Runner.Worker.Dap
                 {
                     Id = completedStep.FrameId,
                     Name = MaskUserVisibleText($"{completedStep.DisplayName}{resultStr}"),
-                    Line = 1,
+                    Source = completedStep.SourceLine.HasValue ? source : null,
+                    Line = completedStep.SourceLine ?? 0,
                     Column = 1,
                     PresentationHint = "subtle"
                 });
@@ -1113,6 +1321,76 @@ namespace GitHub.Runner.Worker.Dap
             return CreateResponse(request, true, body: body);
         }
 
+        private Source BuildJobStepsSource(JobExecutionView snapshot)
+        {
+            return new Source
+            {
+                Name = MaskUserVisibleText(snapshot.SourceFileName),
+                Path = MaskUserVisibleText($"{SanitizeSourcePathSegment(snapshot.JobId)}/{snapshot.SourceFileName}"),
+                SourceReference = _jobStepsSourceReference,
+                PresentationHint = "normal"
+            };
+        }
+
+        private static string SanitizeSourcePathSegment(string value)
+        {
+            if (string.IsNullOrWhiteSpace(value))
+            {
+                return "job";
+            }
+
+            var builder = new StringBuilder(value.Length);
+            foreach (var character in value)
+            {
+                builder.Append(char.IsControl(character) || character == '/' || character == '\\'
+                    ? '_'
+                    : character);
+            }
+
+            return builder.Length == 0 ? "job" : builder.ToString();
+        }
+
+        internal Response HandleSource(Request request)
+        {
+            SourceArguments args;
+            try
+            {
+                args = request.Arguments?.ToObject<SourceArguments>();
+            }
+            catch (Exception ex)
+            {
+                Trace.Warning($"Failed to parse source arguments: {ex.GetType().Name}");
+                return CreateResponse(request, false, "Invalid source arguments.", body: null);
+            }
+
+            var sourceReference = args?.Source?.SourceReference ?? args?.SourceReference;
+            if (!sourceReference.HasValue)
+            {
+                return CreateResponse(request, false, "Missing source reference.", body: null);
+            }
+
+            JobExecutionView snapshot;
+            lock (_stateLock)
+            {
+                snapshot = _jobStepsSource;
+            }
+
+            if (snapshot == null)
+            {
+                return CreateResponse(request, false, "Job steps source not yet available.", body: null);
+            }
+
+            if (sourceReference.Value != _jobStepsSourceReference)
+            {
+                return CreateResponse(request, false, $"Unknown source reference: {sourceReference.Value}.", body: null);
+            }
+
+            return CreateResponse(request, true, body: new SourceResponseBody
+            {
+                Content = MaskUserVisibleText(snapshot.Content)
+            });
+        }
+
         private Response HandleScopes(Request request)
         {
             var args = request.Arguments?.ToObject<ScopesArguments>();

src/Runner.Worker/Dap/DapMessages.cs

@@ -537,6 +537,46 @@ namespace GitHub.Runner.Worker.Dap
 
     #endregion
 
+    #region Source Request/Response
+
+    /// <summary>
+    /// Arguments for 'source' request.
+    /// </summary>
+    public class SourceArguments
+    {
+        /// <summary>
+        /// Source descriptor. Some clients send sourceReference only here.
+        /// </summary>
+        [JsonProperty("source", NullValueHandling = NullValueHandling.Ignore)]
+        public Source Source { get; set; }
+
+        /// <summary>
+        /// The reference to the source.
+        /// </summary>
+        [JsonProperty("sourceReference", NullValueHandling = NullValueHandling.Ignore)]
+        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 Scopes Request/Response
 
     /// <summary>

src/Runner.Worker/Dap/IDapDebugger.cs

@@ -1,4 +1,5 @@
-using System.Threading.Tasks;
+using System.Collections.Generic;
+using System.Threading.Tasks;
 using GitHub.Runner.Common;
 
 namespace GitHub.Runner.Worker.Dap
@@ -19,6 +20,8 @@ namespace GitHub.Runner.Worker.Dap
     {
         Task StartAsync(IExecutionContext jobContext);
         Task WaitUntilReadyAsync();
+        Task OnJobStepsInitializedAsync(IEnumerable<IStep> steps, IEnumerable<IStep> initialPostSteps);
+        void OnPostStepRegistered(IStep step);
         Task OnStepStartingAsync(IStep step);
         void OnStepCompleted(IStep step);
         Task OnJobCompletedAsync();

src/Runner.Worker/Dap/JobExecutionView.cs

@@ -0,0 +1,358 @@
+using System;
+using System.Collections.Generic;
+using System.Globalization;
+using System.Text;
+
+namespace GitHub.Runner.Worker.Dap
+{
+    internal sealed class JobExecutionView
+    {
+        private const string _sourceFileName = "execution.yml";
+
+        private readonly object _lock = new object();
+        private readonly List<SourceEntry> _preEntries = new List<SourceEntry>();
+        private readonly List<SourceEntry> _mainEntries = new List<SourceEntry>();
+        private readonly List<SourceEntry> _postEntries = new List<SourceEntry>();
+        private readonly List<StepLine> _lineByStep = new List<StepLine>();
+        private string _content;
+        private int _completeJobLine;
+
+        public JobExecutionView(
+            string jobId,
+            IEnumerable<IStep> steps,
+            IEnumerable<IStep> initialPostSteps,
+            IEnumerable<PredictedPostStep> predictedPostSteps = null)
+        {
+            JobId = string.IsNullOrWhiteSpace(jobId) ? "job" : jobId;
+
+            _preEntries.Add(new SourceEntry("Setup job"));
+            AddSteps(steps);
+            AddPredictedPostSteps(predictedPostSteps);
+            AddSteps(initialPostSteps);
+            _postEntries.Add(SourceEntry.CreateSyntheticCompleteJob());
+            Render();
+        }
+
+        public string JobId { get; }
+        public string SourceFileName => _sourceFileName;
+
+        public string Content
+        {
+            get
+            {
+                lock (_lock)
+                {
+                    return _content;
+                }
+            }
+        }
+
+        public int CompleteJobLine
+        {
+            get
+            {
+                lock (_lock)
+                {
+                    return _completeJobLine;
+                }
+            }
+        }
+
+        public int? TryClaimPredictedStep(string matchKey, IStep step)
+        {
+            if (string.IsNullOrEmpty(matchKey) || step == null)
+            {
+                return null;
+            }
+
+            lock (_lock)
+            {
+                var existingLine = TryGetLineForStepNoLock(step);
+                if (existingLine.HasValue)
+                {
+                    return existingLine;
+                }
+
+                foreach (var entry in _postEntries)
+                {
+                    if (!string.Equals(entry.MatchKey, matchKey, StringComparison.Ordinal))
+                    {
+                        continue;
+                    }
+
+                    if (entry.Step != null && !ReferenceEquals(entry.Step, step))
+                    {
+                        return null;
+                    }
+
+                    entry.Step = step;
+                    Render();
+                    return TryGetLineForStepNoLock(step);
+                }
+
+                return null;
+            }
+        }
+
+        public int? TryGetLineForStep(IStep step)
+        {
+            if (step == null)
+            {
+                return null;
+            }
+
+            lock (_lock)
+            {
+                return TryGetLineForStepNoLock(step);
+            }
+        }
+
+        private int? TryGetLineForStepNoLock(IStep step)
+        {
+            foreach (var stepLine in _lineByStep)
+            {
+                if (ReferenceEquals(stepLine.Step, step))
+                {
+                    return stepLine.Line;
+                }
+            }
+
+            return null;
+        }
+
+        private void AddSteps(IEnumerable<IStep> steps)
+        {
+            if (steps == null)
+            {
+                return;
+            }
+
+            foreach (var step in steps)
+            {
+                if (step == null)
+                {
+                    continue;
+                }
+
+                GetEntries(GetSection(step)).Add(new SourceEntry(step));
+            }
+        }
+
+        private void AddPredictedPostSteps(IEnumerable<PredictedPostStep> steps)
+        {
+            if (steps == null)
+            {
+                return;
+            }
+
+            foreach (var step in steps)
+            {
+                if (step == null)
+                {
+                    continue;
+                }
+
+                _postEntries.Add(new SourceEntry(step.DisplayName, step.MatchKey));
+            }
+        }
+
+        private List<SourceEntry> GetEntries(SourceSection section)
+        {
+            switch (section)
+            {
+                case SourceSection.Pre:
+                    return _preEntries;
+                case SourceSection.Post:
+                    return _postEntries;
+                default:
+                    return _mainEntries;
+            }
+        }
+
+        private static SourceSection GetSection(IStep step)
+        {
+            if (step is IActionRunner actionRunner)
+            {
+                return GetSection(actionRunner.Stage);
+            }
+
+            if (step.ExecutionContext != null)
+            {
+                return GetSection(step.ExecutionContext.Stage);
+            }
+
+            return SourceSection.Main;
+        }
+
+        private static SourceSection GetSection(ActionRunStage stage)
+        {
+            switch (stage)
+            {
+                case ActionRunStage.Pre:
+                    return SourceSection.Pre;
+                case ActionRunStage.Post:
+                    return SourceSection.Post;
+                default:
+                    return SourceSection.Main;
+            }
+        }
+
+        private void Render()
+        {
+            _lineByStep.Clear();
+            _completeJobLine = 0;
+
+            var sb = new StringBuilder();
+            var line = 1;
+
+            AppendSection(sb, "pre", _preEntries, ref line, appendSeparatorLine: true);
+            AppendSection(sb, "main", _mainEntries, ref line, appendSeparatorLine: true);
+            AppendSection(sb, "post", _postEntries, ref line, appendSeparatorLine: false);
+
+            _content = sb.ToString();
+        }
+
+        private void AppendSection(
+            StringBuilder sb,
+            string sectionName,
+            IReadOnlyList<SourceEntry> entries,
+            ref int line,
+            bool appendSeparatorLine)
+        {
+            sb.Append(sectionName).Append(":\n");
+            line++;
+
+            foreach (var entry in entries)
+            {
+                if (entry.Step != null && TryGetLineForStepNoLock(entry.Step) == null)
+                {
+                    _lineByStep.Add(new StepLine(entry.Step, line));
+                }
+
+                sb.Append("  - step: ");
+                sb.Append(FormatYamlString(entry.DisplayName));
+                sb.Append('\n');
+                if (entry.IsSyntheticCompleteJob)
+                {
+                    _completeJobLine = line;
+                }
+
+                line++;
+            }
+
+            if (appendSeparatorLine)
+            {
+                sb.Append('\n');
+                line++;
+            }
+        }
+
+        private static string FormatYamlString(string value)
+        {
+            var sb = new StringBuilder();
+            sb.Append('"');
+            foreach (var c in value)
+            {
+                switch (c)
+                {
+                    case '\\':
+                        sb.Append(@"\\");
+                        break;
+                    case '"':
+                        sb.Append("\\\"");
+                        break;
+                    case '\r':
+                        sb.Append(@"\r");
+                        break;
+                    case '\n':
+                        sb.Append(@"\n");
+                        break;
+                    case '\t':
+                        sb.Append(@"\t");
+                        break;
+                    default:
+                        if (char.IsControl(c))
+                        {
+                            sb.Append(@"\u");
+                            sb.Append(((int)c).ToString("x4", CultureInfo.InvariantCulture));
+                        }
+                        else
+                        {
+                            sb.Append(c);
+                        }
+                        break;
+                }
+            }
+
+            sb.Append('"');
+            return sb.ToString();
+        }
+
+        internal sealed class PredictedPostStep
+        {
+            public PredictedPostStep(string displayName, string matchKey)
+            {
+                DisplayName = string.IsNullOrEmpty(displayName) ? "step" : displayName;
+                MatchKey = matchKey;
+            }
+
+            public string DisplayName { get; }
+            public string MatchKey { get; }
+        }
+
+        private sealed class StepLine
+        {
+            public StepLine(IStep step, int line)
+            {
+                Step = step;
+                Line = line;
+            }
+
+            public IStep Step { get; }
+            public int Line { get; }
+        }
+
+        private sealed class SourceEntry
+        {
+            public SourceEntry(string displayName)
+            {
+                DisplayName = string.IsNullOrEmpty(displayName) ? "step" : displayName;
+            }
+
+            public SourceEntry(string displayName, string matchKey)
+                : this(displayName)
+            {
+                MatchKey = matchKey;
+            }
+
+            public SourceEntry(IStep step)
+            {
+                Step = step;
+                DisplayName = string.IsNullOrEmpty(step.DisplayName) ? "step" : step.DisplayName;
+            }
+
+            private SourceEntry(string displayName, bool isSyntheticCompleteJob)
+                : this(displayName)
+            {
+                IsSyntheticCompleteJob = isSyntheticCompleteJob;
+            }
+
+            public static SourceEntry CreateSyntheticCompleteJob()
+            {
+                return new SourceEntry("Complete job", isSyntheticCompleteJob: true);
+            }
+
+            public IStep Step { get; set; }
+            public string DisplayName { get; }
+            public string MatchKey { get; }
+            public bool IsSyntheticCompleteJob { get; }
+        }
+
+        private enum SourceSection
+        {
+            Pre,
+            Main,
+            Post
+        }
+    }
+}

src/Runner.Worker/Dap/JobExecutionViewRenderer.cs

@@ -1,336 +0,0 @@
-using System;
-using System.Collections.Generic;
-using System.Globalization;
-using System.Text;
-using GitHub.Runner.Sdk;
-
-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>
-    /// 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(YamlScalarFormatter.Format(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(YamlScalarFormatter.Format(entry.DisplayName));
-                sb.Append('\n');
-                newlinesEmitted++;
-
-                switch (phase)
-                {
-                    case JobExecutionPhase.Pre:
-                    case JobExecutionPhase.Post:
-                        if (!string.IsNullOrEmpty(entry.Uses))
-                        {
-                            sb.Append("    action: ").Append(YamlScalarFormatter.Format(entry.Uses)).Append('\n');
-                            newlinesEmitted++;
-                        }
-                        // No source: annotation for pre/post.
-                        break;
-
-                    case JobExecutionPhase.Main:
-                        if (!string.IsNullOrEmpty(entry.Id))
-                        {
-                            sb.Append("    id: ").Append(YamlScalarFormatter.Format(entry.Id)).Append('\n');
-                            newlinesEmitted++;
-                        }
-                        if (!string.IsNullOrEmpty(entry.Uses))
-                        {
-                            sb.Append("    uses: ").Append(YamlScalarFormatter.Format(entry.Uses)).Append('\n');
-                            newlinesEmitted++;
-                        }
-                        if (!string.IsNullOrEmpty(entry.Run))
-                        {
-                            if (entry.Run.IndexOf('\n') < 0)
-                            {
-                                sb.Append("    run: ").Append(YamlScalarFormatter.Format(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(YamlScalarFormatter.Format(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(YamlScalarFormatter.Format(entry.Shell)).Append('\n');
-                            newlinesEmitted++;
-                        }
-                        if (!string.IsNullOrEmpty(entry.WorkingDirectory))
-                        {
-                            sb.Append("    working-directory: ").Append(YamlScalarFormatter.Format(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;
-        }
-    }
-}

src/Runner.Worker/Dap/YamlScalarFormatter.cs

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

src/Runner.Worker/ExecutionContext.cs

@@ -337,7 +337,25 @@ namespace GitHub.Runner.Worker
             }
 
             step.ExecutionContext = Root.CreatePostChild(step.DisplayName, IntraActionState, siblingScopeName);
+            if (step is JobExtensionRunner)
+            {
+                step.ExecutionContext.StepTelemetry.Type = "runner";
+                step.ExecutionContext.StepTelemetry.Action = step.DisplayName.ToLowerInvariant().Replace(' ', '_');
+            }
             Root.PostJobSteps.Push(step);
+
+            if (Root.Global.Debugger?.Enabled == true)
+            {
+                try
+                {
+                    HostContext.GetService<Dap.IDapDebugger>().OnPostStepRegistered(step);
+                }
+                catch (Exception ex)
+                {
+                    Trace.Warning("Failed to notify DAP debugger about registered post job step.");
+                    Trace.Error(ex);
+                }
+            }
         }
 
         public IExecutionContext CreateChild(

src/Runner.Worker/Handlers/NodeScriptActionHandler.cs

@@ -12,6 +12,7 @@ using GitHub.Runner.Common.Util;
 using GitHub.Runner.Sdk;
 using GitHub.Runner.Worker.Container;
 using GitHub.Runner.Worker.Container.ContainerHooks;
+using GitHub.Services.Common;
 
 namespace GitHub.Runner.Worker.Handlers
 {
@@ -128,6 +129,15 @@ namespace GitHub.Runner.Worker.Handlers
             // file name character on Linux.
             string arguments = StepHost.ResolvePathForStepHost(ExecutionContext, StringUtil.Format(@"""{0}""", target.Replace(@"""", @"\""")));
 
+            // Disable maglev jit compiler in node.js 24.x.x on x64 Windows until the node.js bug is fixed.
+            // https://github.com/nodejs/node/issues/62260
+            if (nodeRuntimeVersion.StartsWith("node24", StringComparison.OrdinalIgnoreCase) &&
+                (StringUtil.ConvertToBoolean(System.Environment.GetEnvironmentVariable("ACTIONS_RUNNER_DISABLE_NODE_MAGLEV")) || StringUtil.ConvertToBoolean(Environment.GetValueOrDefault("ACTIONS_RUNNER_DISABLE_NODE_MAGLEV"))))
+            {
+                Trace.Info("Disable maglev jit compiler in node.js");
+                arguments = $"--no-maglev {arguments}";
+            }
+
 #if OS_WINDOWS
             // It appears that node.exe outputs UTF8 when not in TTY mode.
             Encoding outputEncoding = Encoding.UTF8;

src/Runner.Worker/JobRunner.cs

@@ -13,6 +13,7 @@ using GitHub.DistributedTask.WebApi;
 using GitHub.Runner.Common;
 using GitHub.Runner.Common.Util;
 using GitHub.Runner.Sdk;
+using GitHub.Runner.Worker.Dap;
 using GitHub.Services.Common;
 using GitHub.Services.WebApi;
 using Sdk.RSWebApi.Contracts;
@@ -230,6 +231,12 @@ namespace GitHub.Runner.Worker
                         jobContext.JobSteps.Enqueue(step);
                     }
 
+                    if (jobContext.Global.Debugger?.Enabled == true)
+                    {
+                        var dapDebugger = HostContext.GetService<IDapDebugger>();
+                        await dapDebugger.OnJobStepsInitializedAsync(jobContext.JobSteps, jobContext.PostJobSteps);
+                    }
+
                     await stepsRunner.RunAsync(jobContext);
                 }
                 catch (Exception ex)

src/Sdk/DTPipelines/workflow-v1.0.json

@@ -186,7 +186,16 @@
         "vars",
         "needs",
         "strategy",
-        "matrix"
+        "matrix",
+        "steps",
+        "job",
+        "runner",
+        "env",
+        "always(0,0)",
+        "failure(0,0)",
+        "cancelled(0,0)",
+        "success(0,0)",
+        "hashFiles(1,255)"
       ],
       "string": {}
     },

src/Sdk/WorkflowParser/Conversion/WorkflowTemplateConverter.cs

@@ -2291,6 +2291,10 @@ namespace GitHub.Actions.WorkflowParser.Conversion
             new NamedValueInfo<NoOperationNamedValue>(WorkflowTemplateConstants.Needs),
             new NamedValueInfo<NoOperationNamedValue>(WorkflowTemplateConstants.Strategy),
             new NamedValueInfo<NoOperationNamedValue>(WorkflowTemplateConstants.Matrix),
+            new NamedValueInfo<NoOperationNamedValue>(WorkflowTemplateConstants.Steps),
+            new NamedValueInfo<NoOperationNamedValue>(WorkflowTemplateConstants.Job),
+            new NamedValueInfo<NoOperationNamedValue>(WorkflowTemplateConstants.Runner),
+            new NamedValueInfo<NoOperationNamedValue>(WorkflowTemplateConstants.Env),
         };
         private static readonly IFunctionInfo[] s_jobConditionFunctions = new IFunctionInfo[]
         {
@@ -2307,6 +2311,13 @@ namespace GitHub.Actions.WorkflowParser.Conversion
             new FunctionInfo<NoOperation>(WorkflowTemplateConstants.Success, 0, 0),
             new FunctionInfo<NoOperation>(WorkflowTemplateConstants.HashFiles, 1, Byte.MaxValue),
         };
-        private static readonly IFunctionInfo[] s_snapshotConditionFunctions = null;
+        private static readonly IFunctionInfo[] s_snapshotConditionFunctions = new IFunctionInfo[]
+        {
+            new FunctionInfo<NoOperation>(WorkflowTemplateConstants.Always, 0, 0),
+            new FunctionInfo<NoOperation>(WorkflowTemplateConstants.Cancelled, 0, 0),
+            new FunctionInfo<NoOperation>(WorkflowTemplateConstants.Failure, 0, 0),
+            new FunctionInfo<NoOperation>(WorkflowTemplateConstants.Success, 0, 0),
+            new FunctionInfo<NoOperation>(WorkflowTemplateConstants.HashFiles, 1, Byte.MaxValue),
+        };
     }
 }

src/Sdk/WorkflowParser/workflow-v1.0.json

@@ -2196,7 +2196,16 @@
         "vars",
         "needs",
         "strategy",
-        "matrix"
+        "matrix",
+        "steps",
+        "job",
+        "runner",
+        "env",
+        "always(0,0)",
+        "failure(0,0)",
+        "cancelled(0,0)",
+        "success(0,0)",
+        "hashFiles(1,255)"
       ],
       "description": "Use the if conditional to prevent a snapshot from being taken unless a condition is met. Any supported context and expression can be used to create a conditional. Expressions in an `if` conditional do not require the bracketed expression syntax. When you use expressions in an `if` conditional, you may omit the expression syntax because GitHub automatically evaluates the `if` conditional as an expression.",
       "string": {

src/Test/L0/Worker/DapDebuggerL0.cs

@@ -11,7 +11,9 @@ using Moq;
 using GitHub.Runner.Worker;
 using GitHub.Runner.Worker.Dap;
 using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
 using Xunit;
+using Pipelines = GitHub.DistributedTask.Pipelines;
 
 namespace GitHub.Runner.Common.Tests.Worker
 {
@@ -255,6 +257,78 @@ namespace GitHub.Runner.Common.Tests.Worker
             return jobContext;
         }
 
+        private static Mock<IStep> CreateStep(string displayName, ActionRunStage? stage = null)
+        {
+            var step = new Mock<IStep>();
+            step.Setup(s => s.DisplayName).Returns(displayName);
+            if (stage.HasValue)
+            {
+                var executionContext = new Mock<IExecutionContext>();
+                executionContext.Setup(x => x.Stage).Returns(stage.Value);
+                step.Setup(s => s.ExecutionContext).Returns(executionContext.Object);
+            }
+            else
+            {
+                step.Setup(s => s.ExecutionContext).Returns((IExecutionContext)null);
+            }
+
+            return step;
+        }
+
+        private static Mock<IActionRunner> CreateActionRunner(string displayName, ActionRunStage stage, Pipelines.ActionStep action)
+        {
+            var executionContext = new Mock<IExecutionContext>();
+            executionContext.Setup(x => x.Stage).Returns(stage);
+
+            var runner = new Mock<IActionRunner>();
+            runner.Setup(s => s.DisplayName).Returns(displayName);
+            runner.Setup(s => s.ExecutionContext).Returns(executionContext.Object);
+            runner.Setup(s => s.Stage).Returns(stage);
+            runner.Setup(s => s.Action).Returns(action);
+            return runner;
+        }
+
+        private static Pipelines.ActionStep CreateRepositoryActionStep(string name)
+        {
+            return new Pipelines.ActionStep
+            {
+                Id = Guid.NewGuid(),
+                Name = name,
+                Reference = new Pipelines.RepositoryPathReference
+                {
+                    Name = name,
+                    Ref = "v1",
+                    RepositoryType = Pipelines.RepositoryTypes.GitHub
+                }
+            };
+        }
+
+        private static Definition CreateActionDefinitionWithPost()
+        {
+            return new Definition
+            {
+                Data = new ActionDefinitionData
+                {
+                    Execution = new NodeJSActionExecutionData
+                    {
+                        Script = "main.js",
+                        Post = "post.js"
+                    }
+                }
+            };
+        }
+
+        private static Request MakeRequest(string command, object arguments)
+        {
+            return new Request
+            {
+                Seq = 1,
+                Type = "request",
+                Command = command,
+                Arguments = JObject.FromObject(arguments)
+            };
+        }
+
         [Fact]
         [Trait("Level", "L0")]
         [Trait("Category", "Worker")]
@@ -718,6 +792,325 @@ namespace GitHub.Runner.Common.Tests.Worker
             }
         }
 
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task HandleSourceReturnsJobStepsSource()
+        {
+            using (var hc = CreateTestContext())
+            {
+                hc.SecretMasker.AddValue("secret-step");
+                var port = GetFreePort();
+                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
+                await _debugger.StartAsync(jobContext.Object);
+
+                var waitTask = _debugger.WaitUntilReadyAsync();
+                using var client = await ConnectClientAsync(port);
+                var stream = client.GetStream();
+                await SendRequestAsync(stream, new Request
+                {
+                    Seq = 1,
+                    Type = "request",
+                    Command = "configurationDone"
+                });
+                await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                await waitTask;
+
+                var pre = CreateStep("Pre cache", ActionRunStage.Pre);
+                var checkout = CreateStep("Checkout");
+                var secret = CreateStep("secret-step");
+                var post = CreateStep("Post cache", ActionRunStage.Post);
+                await _debugger.OnJobStepsInitializedAsync(
+                    new[] { pre.Object, checkout.Object, secret.Object },
+                    new[] { post.Object });
+
+                var response = _debugger.HandleSource(MakeRequest(
+                    "source",
+                    new SourceArguments { SourceReference = 1 }));
+
+                Assert.True(response.Success);
+                var body = Assert.IsType<SourceResponseBody>(response.Body);
+                Assert.Equal(
+                    "pre:\n  - step: \"Setup job\"\n  - step: \"Pre cache\"\n\nmain:\n  - step: \"Checkout\"\n  - step: \"***\"\n\npost:\n  - step: \"Post cache\"\n  - step: \"Complete job\"\n",
+                    body.Content);
+                Assert.Null(body.MimeType);
+
+                await _debugger.StopAsync();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task StackTraceUsesJobStepsSourceLine()
+        {
+            using (CreateTestContext())
+            {
+                var port = GetFreePort();
+                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
+                await _debugger.StartAsync(jobContext.Object);
+
+                var waitTask = _debugger.WaitUntilReadyAsync();
+                using var client = await ConnectClientAsync(port);
+                var stream = client.GetStream();
+                await SendRequestAsync(stream, new Request
+                {
+                    Seq = 1,
+                    Type = "request",
+                    Command = "configurationDone"
+                });
+                await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                await waitTask;
+
+                var checkout = CreateStep("Checkout");
+                var build = CreateStep("Build");
+                await _debugger.OnJobStepsInitializedAsync(
+                    new[] { checkout.Object, build.Object },
+                    Array.Empty<IStep>());
+
+                var stepTask = _debugger.OnStepStartingAsync(build.Object);
+                var stoppedEvent = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                Assert.Contains("\"event\":\"stopped\"", stoppedEvent);
+
+                var bannerEvent = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                Assert.Contains("\"event\":\"output\"", bannerEvent);
+
+                await SendRequestAsync(stream, new Request
+                {
+                    Seq = 2,
+                    Type = "request",
+                    Command = "stackTrace"
+                });
+
+                var stackTraceJson = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                var stackTrace = JObject.Parse(stackTraceJson);
+                var frame = stackTrace["body"]?["stackFrames"]?[0];
+
+                Assert.NotNull(frame);
+                Assert.Equal(6, frame["line"].Value<int>());
+                Assert.Equal(1, frame["source"]["sourceReference"].Value<int>());
+                Assert.Equal("execution.yml", frame["source"]["name"].Value<string>());
+
+                await SendRequestAsync(stream, new Request
+                {
+                    Seq = 3,
+                    Type = "request",
+                    Command = "continue"
+                });
+                await stepTask;
+
+                await _debugger.StopAsync();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task StackTraceOmitsSourceForUnmappedCurrentStep()
+        {
+            using (CreateTestContext())
+            {
+                var port = GetFreePort();
+                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
+                await _debugger.StartAsync(jobContext.Object);
+
+                var waitTask = _debugger.WaitUntilReadyAsync();
+                using var client = await ConnectClientAsync(port);
+                var stream = client.GetStream();
+                await SendRequestAsync(stream, new Request
+                {
+                    Seq = 1,
+                    Type = "request",
+                    Command = "configurationDone"
+                });
+                await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                await waitTask;
+
+                var checkout = CreateStep("Checkout");
+                var build = CreateStep("Build");
+                await _debugger.OnJobStepsInitializedAsync(
+                    new[] { checkout.Object },
+                    Array.Empty<IStep>());
+
+                var stepTask = _debugger.OnStepStartingAsync(build.Object);
+                await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+
+                await SendRequestAsync(stream, new Request
+                {
+                    Seq = 2,
+                    Type = "request",
+                    Command = "stackTrace"
+                });
+
+                var stackTraceJson = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                var stackTrace = JObject.Parse(stackTraceJson);
+                var frame = stackTrace["body"]?["stackFrames"]?[0];
+
+                Assert.NotNull(frame);
+                Assert.Equal(0, frame["line"].Value<int>());
+                Assert.Null(frame["source"]);
+
+                await SendRequestAsync(stream, new Request
+                {
+                    Seq = 3,
+                    Type = "request",
+                    Command = "continue"
+                });
+                await stepTask;
+
+                await _debugger.StopAsync();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task PredictedPostStepIsServedAtInitializationAndClaimedAtRegistration()
+        {
+            using (var hc = CreateTestContext())
+            {
+                var action = CreateRepositoryActionStep("actions/cache");
+                var actionManager = new Mock<IActionManager>();
+                actionManager
+                    .Setup(x => x.LoadAction(It.IsAny<IExecutionContext>(), action))
+                    .Returns(CreateActionDefinitionWithPost());
+                hc.SetSingleton<IActionManager>(actionManager.Object);
+
+                var port = GetFreePort();
+                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
+                await _debugger.StartAsync(jobContext.Object);
+
+                var waitTask = _debugger.WaitUntilReadyAsync();
+                using var client = await ConnectClientAsync(port);
+                var stream = client.GetStream();
+                await SendRequestAsync(stream, new Request
+                {
+                    Seq = 1,
+                    Type = "request",
+                    Command = "configurationDone"
+                });
+                await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                await waitTask;
+
+                var checkout = CreateActionRunner("Checkout", ActionRunStage.Main, action);
+                await _debugger.OnJobStepsInitializedAsync(
+                    new[] { checkout.Object },
+                    Array.Empty<IStep>());
+
+                var sourceResponse = _debugger.HandleSource(MakeRequest(
+                    "source",
+                    new SourceArguments { SourceReference = 1 }));
+                var sourceBody = Assert.IsType<SourceResponseBody>(sourceResponse.Body);
+                Assert.Equal(
+                    "pre:\n  - step: \"Setup job\"\n\nmain:\n  - step: \"Checkout\"\n\npost:\n  - step: \"Post Checkout\"\n  - step: \"Complete job\"\n",
+                    sourceBody.Content);
+
+                var post = CreateActionRunner("Post Checkout", ActionRunStage.Post, action);
+                _debugger.OnPostStepRegistered(post.Object);
+
+                var stepTask = _debugger.OnStepStartingAsync(post.Object);
+                var stoppedEvent = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                Assert.Contains("\"event\":\"stopped\"", stoppedEvent);
+
+                var bannerEvent = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                Assert.Contains("\"event\":\"output\"", bannerEvent);
+
+                await SendRequestAsync(stream, new Request
+                {
+                    Seq = 2,
+                    Type = "request",
+                    Command = "stackTrace"
+                });
+
+                var stackTraceJson = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                var stackTrace = JObject.Parse(stackTraceJson);
+                var frame = stackTrace["body"]?["stackFrames"]?[0];
+
+                Assert.NotNull(frame);
+                Assert.Equal(8, frame["line"].Value<int>());
+                Assert.Equal(1, frame["source"]["sourceReference"].Value<int>());
+
+                await SendRequestAsync(stream, new Request
+                {
+                    Seq = 3,
+                    Type = "request",
+                    Command = "continue"
+                });
+                await stepTask;
+
+                await _debugger.StopAsync();
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task StackTraceSanitizesSyntheticSourcePath()
+        {
+            using (CreateTestContext())
+            {
+                var port = GetFreePort();
+                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+                var jobContext = CreateJobContextWithTunnel(cts.Token, port, jobName: "my/job\\name");
+                await _debugger.StartAsync(jobContext.Object);
+
+                var waitTask = _debugger.WaitUntilReadyAsync();
+                using var client = await ConnectClientAsync(port);
+                var stream = client.GetStream();
+                await SendRequestAsync(stream, new Request
+                {
+                    Seq = 1,
+                    Type = "request",
+                    Command = "configurationDone"
+                });
+                await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                await waitTask;
+
+                var checkout = CreateStep("Checkout");
+                await _debugger.OnJobStepsInitializedAsync(
+                    new[] { checkout.Object },
+                    Array.Empty<IStep>());
+
+                var stepTask = _debugger.OnStepStartingAsync(checkout.Object);
+                await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+
+                await SendRequestAsync(stream, new Request
+                {
+                    Seq = 2,
+                    Type = "request",
+                    Command = "stackTrace"
+                });
+
+                var stackTraceJson = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                var stackTrace = JObject.Parse(stackTraceJson);
+                var frame = stackTrace["body"]?["stackFrames"]?[0];
+
+                Assert.NotNull(frame);
+                Assert.Equal("my_job_name/execution.yml", frame["source"]["path"].Value<string>());
+
+                await SendRequestAsync(stream, new Request
+                {
+                    Seq = 3,
+                    Type = "request",
+                    Command = "continue"
+                });
+                await stepTask;
+
+                await _debugger.StopAsync();
+            }
+        }
+
         [Fact]
         [Trait("Level", "L0")]
         [Trait("Category", "Worker")]
@@ -746,6 +1139,11 @@ namespace GitHub.Runner.Common.Tests.Worker
                 await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
                 await waitTask;
 
+                var checkout = CreateStep("Checkout");
+                await _debugger.OnJobStepsInitializedAsync(
+                    new[] { checkout.Object },
+                    Array.Empty<IStep>());
+
                 // Complete the job — OnJobCompletedAsync pauses when stepping,
                 // so run it in the background and send continue to unblock.
                 var completedTask = _debugger.OnJobCompletedAsync();
@@ -754,11 +1152,27 @@ namespace GitHub.Runner.Common.Tests.Worker
                 var stoppedMsg = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
                 Assert.Contains("\"event\":\"stopped\"", stoppedMsg);
 
-                // Send continue to unblock the pause
                 await SendRequestAsync(stream, new Request
                 {
                     Seq = 2,
                     Type = "request",
+                    Command = "stackTrace"
+                });
+
+                var stackTraceJson = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                var stackTrace = JObject.Parse(stackTraceJson);
+                var frame = stackTrace["body"]?["stackFrames"]?[0];
+
+                Assert.NotNull(frame);
+                Assert.Equal("Complete job [completed]", frame["name"].Value<string>());
+                Assert.Equal(8, frame["line"].Value<int>());
+                Assert.Equal(1, frame["source"]["sourceReference"].Value<int>());
+
+                // Send continue to unblock the pause
+                await SendRequestAsync(stream, new Request
+                {
+                    Seq = 3,
+                    Type = "request",
                     Command = "continue"
                 });
 
@@ -777,6 +1191,68 @@ namespace GitHub.Runner.Common.Tests.Worker
             }
         }
 
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public async Task OnJobCompletedUsesSyntheticCompleteJobLineWhenPostStepSharesName()
+        {
+            using (CreateTestContext())
+            {
+                var port = GetFreePort();
+                using var cts = new CancellationTokenSource(TimeSpan.FromSeconds(10));
+                var jobContext = CreateJobContextWithTunnel(cts.Token, port);
+                await _debugger.StartAsync(jobContext.Object);
+
+                var waitTask = _debugger.WaitUntilReadyAsync();
+                using var client = await ConnectClientAsync(port);
+                var stream = client.GetStream();
+                await SendRequestAsync(stream, new Request
+                {
+                    Seq = 1,
+                    Type = "request",
+                    Command = "configurationDone"
+                });
+
+                await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                await waitTask;
+
+                var checkout = CreateStep("Checkout");
+                var realPost = CreateStep("Complete job", ActionRunStage.Post);
+                await _debugger.OnJobStepsInitializedAsync(
+                    new[] { checkout.Object },
+                    new[] { realPost.Object });
+
+                var completedTask = _debugger.OnJobCompletedAsync();
+
+                await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+
+                await SendRequestAsync(stream, new Request
+                {
+                    Seq = 2,
+                    Type = "request",
+                    Command = "stackTrace"
+                });
+
+                var stackTraceJson = await ReadDapMessageAsync(stream, TimeSpan.FromSeconds(5));
+                var stackTrace = JObject.Parse(stackTraceJson);
+                var frame = stackTrace["body"]?["stackFrames"]?[0];
+
+                Assert.NotNull(frame);
+                Assert.Equal("Complete job [completed]", frame["name"].Value<string>());
+                Assert.Equal(9, frame["line"].Value<int>());
+
+                await SendRequestAsync(stream, new Request
+                {
+                    Seq = 3,
+                    Type = "request",
+                    Command = "continue"
+                });
+
+                await completedTask;
+            }
+        }
+
         [Fact]
         [Trait("Level", "L0")]
         [Trait("Category", "Worker")]

src/Test/L0/Worker/DapMessagesL0.cs

@@ -1,4 +1,4 @@
-using System.Collections.Generic;
+using System.Collections.Generic;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Linq;
 using Xunit;
@@ -171,6 +171,36 @@ namespace GitHub.Runner.Common.Tests.Worker
             Assert.Equal("normal", deserialized.PresentationHint);
         }
 
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void SourceRequestAndResponseSerialization()
+        {
+            var args = new SourceArguments
+            {
+                Source = new Source
+                {
+                    SourceReference = 1
+                }
+            };
+
+            var argsJson = JsonConvert.SerializeObject(args);
+            var deserializedArgs = JsonConvert.DeserializeObject<SourceArguments>(argsJson);
+
+            Assert.Equal(1, deserializedArgs.Source.SourceReference);
+
+            var body = new SourceResponseBody
+            {
+                Content = "pre:\n  - step: \"Setup job\"\n\nmain:\n  - step: \"Checkout\"\n\npost:\n  - step: \"Complete job\"\n"
+            };
+
+            var bodyJson = JsonConvert.SerializeObject(body);
+            var deserializedBody = JsonConvert.DeserializeObject<SourceResponseBody>(bodyJson);
+
+            Assert.Equal("pre:\n  - step: \"Setup job\"\n\nmain:\n  - step: \"Checkout\"\n\npost:\n  - step: \"Complete job\"\n", deserializedBody.Content);
+            Assert.Null(deserializedBody.MimeType);
+        }
+
         [Fact]
         [Trait("Level", "L0")]
         [Trait("Category", "Worker")]

src/Test/L0/Worker/ExecutionContextL0.cs

@@ -361,6 +361,119 @@ namespace GitHub.Runner.Common.Tests.Worker
             }
         }
 
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void RegisterPostJobStep_JobExtensionRunner_DefaultsRunnerTelemetry()
+        {
+            using (TestHostContext hc = CreateTestContext())
+            {
+                // Arrange: Create a job request message.
+                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 pagingLogger1 = new Mock<IPagingLogger>();
+                var pagingLogger2 = new Mock<IPagingLogger>();
+                var jobServerQueue = new Mock<IJobServerQueue>();
+                jobServerQueue.Setup(x => x.QueueTimelineRecordUpdate(It.IsAny<Guid>(), It.IsAny<TimelineRecord>()));
+
+                hc.EnqueueInstance(pagingLogger1.Object);
+                hc.EnqueueInstance(pagingLogger2.Object);
+                hc.SetSingleton(jobServerQueue.Object);
+
+                var jobContext = new Runner.Worker.ExecutionContext();
+                jobContext.Initialize(hc);
+
+                // Act.
+                jobContext.InitializeJob(jobRequest, CancellationToken.None);
+
+                var extensionStep = new JobExtensionRunner(
+                    runAsync: (_, _) => System.Threading.Tasks.Task.CompletedTask,
+                    condition: "always()",
+                    displayName: "Create Custom Image",
+                    data: null);
+
+                jobContext.RegisterPostJobStep(extensionStep);
+
+                // Assert: telemetry defaults are populated for non-action post-job steps.
+                Assert.NotNull(extensionStep.ExecutionContext);
+                Assert.Equal("runner", extensionStep.ExecutionContext.StepTelemetry.Type);
+                Assert.Equal("create_custom_image", extensionStep.ExecutionContext.StepTelemetry.Action);
+            }
+        }
+
+        [Fact]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Worker")]
+        public void RegisterPostJobStep_ActionRunner_DoesNotOverrideTelemetry()
+        {
+            using (TestHostContext hc = CreateTestContext())
+            {
+                // Arrange: Create a job request message.
+                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 pagingLogger1 = new Mock<IPagingLogger>();
+                var pagingLogger2 = new Mock<IPagingLogger>();
+                var pagingLogger3 = new Mock<IPagingLogger>();
+                var pagingLogger4 = new Mock<IPagingLogger>();
+                var jobServerQueue = new Mock<IJobServerQueue>();
+                jobServerQueue.Setup(x => x.QueueTimelineRecordUpdate(It.IsAny<Guid>(), It.IsAny<TimelineRecord>()));
+
+                var actionRunner = new ActionRunner();
+                actionRunner.Initialize(hc);
+
+                hc.EnqueueInstance(pagingLogger1.Object);
+                hc.EnqueueInstance(pagingLogger2.Object);
+                hc.EnqueueInstance(pagingLogger3.Object);
+                hc.EnqueueInstance(pagingLogger4.Object);
+                hc.EnqueueInstance(actionRunner as IActionRunner);
+                hc.SetSingleton(jobServerQueue.Object);
+
+                var jobContext = new Runner.Worker.ExecutionContext();
+                jobContext.Initialize(hc);
+
+                // Act.
+                jobContext.InitializeJob(jobRequest, CancellationToken.None);
+
+                var action = jobContext.CreateChild(Guid.NewGuid(), "action", "action", null, null, 0);
+
+                var postRunner = hc.CreateService<IActionRunner>();
+                postRunner.Action = new Pipelines.ActionStep() { Id = Guid.NewGuid(), Name = "post", DisplayName = "Post Action", Reference = new Pipelines.RepositoryPathReference() { Name = "actions/action" } };
+                postRunner.Stage = ActionRunStage.Post;
+                postRunner.Condition = "always()";
+                postRunner.DisplayName = "Post Action";
+
+                action.RegisterPostJobStep(postRunner);
+
+                // Assert: action post-step telemetry is left for the handler to fill in,
+                // so RegisterPostJobStep should NOT pre-populate runner-owned defaults.
+                Assert.NotNull(postRunner.ExecutionContext);
+                Assert.Null(postRunner.ExecutionContext.StepTelemetry.Type);
+                Assert.Null(postRunner.ExecutionContext.StepTelemetry.Action);
+            }
+        }
+
         [Fact]
         [Trait("Level", "L0")]
         [Trait("Category", "Worker")]

src/Test/L0/Worker/JobExecutionViewRendererL0.cs

@@ -1,598 +0,0 @@
-using System;
-using System.Collections.Generic;
-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_AlwaysUsesLfLineBreaks()
-        {
-            // Regression: YamlDotNet's Emitter calls WriteLine, which on
-            // Windows produces CRLF (the host's Environment.NewLine).
-            // The renderer's hand-emitted skeleton always uses '\n'; this
-            // test asserts the scalar formatter doesn't sneak CRLF in.
-            var entry = new JobExecutionViewEntry(JobExecutionPhase.Main, "with: colon", id: "step-1", uses: "actions/checkout@v4");
-            var result = JobExecutionViewRenderer.Render("job-1", new[] { entry });
-            Assert.DoesNotContain("\r", result.Yaml);
-        }
-    }
-}

src/Test/L0/Worker/YamlScalarFormatterL0.cs

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