feat: Enhance Task Runner with simulation and failure policy support

- Added tests for output projection and failure policy population in TaskPackPlanner.
- Introduced new failure policy manifest in TestManifests.
- Implemented simulation endpoints in the web service for task execution.
- Created TaskRunnerServiceOptions for configuration management.
- Updated appsettings.json to include TaskRunner configuration.
- Enhanced PackRunWorkerService to handle execution graphs and state management.
- Added support for parallel execution and conditional steps in the worker service.
- Updated documentation to reflect new features and changes in execution flow.

src/TaskRunner/StellaOps.TaskRunner/StellaOps.TaskRunner.Infrastructure/Execution/FilePackRunStateStore.cs

@@ -0,0 +1,191 @@
+using System.Text.Json;
+using StellaOps.TaskRunner.Core.Execution;
+using StellaOps.TaskRunner.Core.Planning;
+
+namespace StellaOps.TaskRunner.Infrastructure.Execution;
+
+/// <summary>
+/// File-system backed implementation of <see cref="IPackRunStateStore"/> intended for development and air-gapped smoke tests.
+/// </summary>
+public sealed class FilePackRunStateStore : IPackRunStateStore
+{
+    private static readonly JsonSerializerOptions SerializerOptions = new(JsonSerializerDefaults.Web)
+    {
+        WriteIndented = true
+    };
+
+    private readonly string rootPath;
+    private readonly SemaphoreSlim mutex = new(1, 1);
+
+    public FilePackRunStateStore(string rootPath)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(rootPath);
+
+        this.rootPath = Path.GetFullPath(rootPath);
+        Directory.CreateDirectory(this.rootPath);
+    }
+
+    public async Task<PackRunState?> GetAsync(string runId, CancellationToken cancellationToken)
+    {
+        ArgumentException.ThrowIfNullOrWhiteSpace(runId);
+
+        var path = GetPath(runId);
+        if (!File.Exists(path))
+        {
+            return null;
+        }
+
+        await using var stream = File.Open(path, FileMode.Open, FileAccess.Read, FileShare.Read);
+        var document = await JsonSerializer.DeserializeAsync<StateDocument>(stream, SerializerOptions, cancellationToken)
+            .ConfigureAwait(false);
+
+        return document?.ToDomain();
+    }
+
+    public async Task SaveAsync(PackRunState state, CancellationToken cancellationToken)
+    {
+        ArgumentNullException.ThrowIfNull(state);
+
+        var path = GetPath(state.RunId);
+        var document = StateDocument.FromDomain(state);
+
+        Directory.CreateDirectory(rootPath);
+
+        await mutex.WaitAsync(cancellationToken).ConfigureAwait(false);
+        try
+        {
+            await using var stream = File.Open(path, FileMode.Create, FileAccess.Write, FileShare.None);
+            await JsonSerializer.SerializeAsync(stream, document, SerializerOptions, cancellationToken)
+                .ConfigureAwait(false);
+        }
+        finally
+        {
+            mutex.Release();
+        }
+    }
+
+    public async Task<IReadOnlyList<PackRunState>> ListAsync(CancellationToken cancellationToken)
+    {
+        if (!Directory.Exists(rootPath))
+        {
+            return Array.Empty<PackRunState>();
+        }
+
+        var states = new List<PackRunState>();
+
+        var files = Directory.EnumerateFiles(rootPath, "*.json", SearchOption.TopDirectoryOnly)
+            .OrderBy(file => file, StringComparer.Ordinal);
+
+        foreach (var file in files)
+        {
+            cancellationToken.ThrowIfCancellationRequested();
+
+            await using var stream = File.Open(file, FileMode.Open, FileAccess.Read, FileShare.Read);
+            var document = await JsonSerializer.DeserializeAsync<StateDocument>(stream, SerializerOptions, cancellationToken)
+                .ConfigureAwait(false);
+
+            if (document is not null)
+            {
+                states.Add(document.ToDomain());
+            }
+        }
+
+        return states;
+    }
+
+    private string GetPath(string runId)
+    {
+        var safeName = SanitizeFileName(runId);
+        return Path.Combine(rootPath, $"{safeName}.json");
+    }
+
+    private static string SanitizeFileName(string value)
+    {
+        var result = value.Trim();
+        foreach (var invalid in Path.GetInvalidFileNameChars())
+        {
+            result = result.Replace(invalid, '_');
+        }
+
+        return result;
+    }
+
+    private sealed record StateDocument(
+        string RunId,
+        string PlanHash,
+        TaskPackPlanFailurePolicy FailurePolicy,
+        DateTimeOffset CreatedAt,
+        DateTimeOffset UpdatedAt,
+        IReadOnlyList<StepDocument> Steps)
+    {
+        public static StateDocument FromDomain(PackRunState state)
+        {
+            var steps = state.Steps.Values
+                .OrderBy(step => step.StepId, StringComparer.Ordinal)
+                .Select(step => new StepDocument(
+                    step.StepId,
+                    step.Kind,
+                    step.Enabled,
+                    step.ContinueOnError,
+                    step.MaxParallel,
+                    step.ApprovalId,
+                    step.GateMessage,
+                    step.Status,
+                    step.Attempts,
+                    step.LastTransitionAt,
+                    step.NextAttemptAt,
+                    step.StatusReason))
+                .ToList();
+
+            return new StateDocument(
+                state.RunId,
+                state.PlanHash,
+                state.FailurePolicy,
+                state.CreatedAt,
+                state.UpdatedAt,
+                steps);
+        }
+
+        public PackRunState ToDomain()
+        {
+            var steps = Steps.ToDictionary(
+                step => step.StepId,
+                step => new PackRunStepStateRecord(
+                    step.StepId,
+                    step.Kind,
+                    step.Enabled,
+                    step.ContinueOnError,
+                    step.MaxParallel,
+                    step.ApprovalId,
+                    step.GateMessage,
+                    step.Status,
+                    step.Attempts,
+                    step.LastTransitionAt,
+                    step.NextAttemptAt,
+                    step.StatusReason),
+                StringComparer.Ordinal);
+
+            return new PackRunState(
+                RunId,
+                PlanHash,
+                FailurePolicy,
+                CreatedAt,
+                UpdatedAt,
+                steps);
+        }
+    }
+
+    private sealed record StepDocument(
+        string StepId,
+        PackRunStepKind Kind,
+        bool Enabled,
+        bool ContinueOnError,
+        int? MaxParallel,
+        string? ApprovalId,
+        string? GateMessage,
+        PackRunStepExecutionStatus Status,
+        int Attempts,
+        DateTimeOffset? LastTransitionAt,
+        DateTimeOffset? NextAttemptAt,
+        string? StatusReason);
+}

src/TaskRunner/StellaOps.TaskRunner/StellaOps.TaskRunner.Infrastructure/Execution/NoopPackRunStepExecutor.cs

@@ -0,0 +1,24 @@
+using System.Text.Json.Nodes;
+using StellaOps.TaskRunner.Core.Execution;
+using StellaOps.TaskRunner.Core.Planning;
+
+namespace StellaOps.TaskRunner.Infrastructure.Execution;
+
+public sealed class NoopPackRunStepExecutor : IPackRunStepExecutor
+{
+    public Task<PackRunStepExecutionResult> ExecuteAsync(
+        PackRunExecutionStep step,
+        IReadOnlyDictionary<string, TaskPackPlanParameterValue> parameters,
+        CancellationToken cancellationToken)
+    {
+        if (parameters.TryGetValue("simulateFailure", out var value) &&
+            value.Value is JsonValue jsonValue &&
+            jsonValue.TryGetValue<bool>(out var failure) &&
+            failure)
+        {
+            return Task.FromResult(new PackRunStepExecutionResult(false, "Simulated failure requested."));
+        }
+
+        return Task.FromResult(new PackRunStepExecutionResult(true));
+    }
+}