Add .NET SDK support to temporal-developer skill

SKILL.md

@@ -1,14 +1,14 @@
 ---
 name: temporal-developer
-description: Develop, debug, and manage Temporal applications across Python, TypeScript, Go, and Java. Use when the user is building workflows, activities, or workers with a Temporal SDK, debugging issues like non-determinism errors, stuck workflows, or activity retries, using Temporal CLI, Temporal Server, or Temporal Cloud, or working with durable execution concepts like signals, queries, heartbeats, versioning, continue-as-new, child workflows, or saga patterns.
+description: Develop, debug, and manage Temporal applications across Python, TypeScript, Go, Java and .NET. Use when the user is building workflows, activities, or workers with a Temporal SDK, debugging issues like non-determinism errors, stuck workflows, or activity retries, using Temporal CLI, Temporal Server, or Temporal Cloud, or working with durable execution concepts like signals, queries, heartbeats, versioning, continue-as-new, child workflows, or saga patterns.
 version: 0.2.0
 ---
 
 # Skill: temporal-developer
 
 ## Overview
 
-Temporal is a durable execution platform that makes workflows survive failures automatically. This skill provides guidance for building Temporal applications in Python, TypeScript, Go, and Java.
+Temporal is a durable execution platform that makes workflows survive failures automatically. This skill provides guidance for building Temporal applications in Python, TypeScript, Go, Java and .NET.
 
 ## Core Architecture
 
@@ -79,8 +79,9 @@ Once you've downloaded the file, extract the downloaded archive and add the temp
 1. First, read the getting started guide for the language you are working in:
    - Python -> read `references/python/python.md`
    - TypeScript -> read `references/typescript/typescript.md`
-   - Java -> read `references/java/java.md`
    - Go -> read `references/go/go.md`
+   - Java -> read `references/java/java.md`
+   - .NET (C#) -> read `references/dotnet/dotnet.md`
 2. Second, read appropriate `core` and language-specific references for the task at hand.
 
 ## Primary References

references/core/determinism.md

@@ -88,6 +88,7 @@ Each Temporal SDK language provides a different level of protection against non-
 - TypeScript: The TypeScript SDK runs workflows in an isolated V8 sandbox, intercepting many common sources of non-determinism and replacing them automatically with deterministic variants.
 - Java: The Java SDK has no sandbox. Determinism is enforced by developer conventions — the SDK provides `Workflow.*` APIs as safe alternatives (e.g., `Workflow.sleep()` instead of `Thread.sleep()`), and non-determinism is only detected at replay time via `NonDeterministicException`. A static analysis tool (`temporal-workflowcheck`, beta) can catch violations at build time. Cooperative threading under a global lock eliminates the need for synchronization.
 - Go: The Go SDK has no runtime sandbox. Therefore, non-determinism bugs will never be immediately appararent, and are usually only observable during replay. The optional `workflowcheck` static analysis tool can be used to check for many sources of non-determinism at compile time.
+- .NET: The .NET SDK has no sandbox. It uses a custom TaskScheduler and a runtime EventListener to detect invalid task scheduling. Developers must use Workflow.* safe alternatives (e.g., Workflow.DelayAsync instead of Task.Delay) and avoid non-deterministic .NET Task APIs.
 
 Regardless of which SDK you are using, it is your responsibility to ensure that workflow code does not contain sources of non-determinism. Use SDK-specific tools as well as replay tests for doing so.
 

references/dotnet/advanced-features.md

@@ -0,0 +1,203 @@
+# .NET SDK Advanced Features
+
+## Schedules
+
+Create recurring workflow executions.
+
+```csharp
+using Temporalio.Client.Schedules;
+
+var scheduleId = "daily-report";
+await client.CreateScheduleAsync(
+    scheduleId,
+    new Schedule(
+        Action: ScheduleActionStartWorkflow.Create(
+            (DailyReportWorkflow wf) => wf.RunAsync(),
+            new(id: "daily-report", taskQueue: "reports")),
+        Spec: new ScheduleSpec
+        {
+            Intervals = new List<ScheduleIntervalSpec>
+            {
+                new(Every: TimeSpan.FromDays(1)),
+            },
+        }));
+
+// Manage schedules
+var handle = client.GetScheduleHandle(scheduleId);
+await handle.PauseAsync("Maintenance window");
+await handle.UnpauseAsync();
+await handle.TriggerAsync(); // Run immediately
+await handle.DeleteAsync();
+```
+
+## Async Activity Completion
+
+For activities that complete asynchronously (e.g., human tasks, external callbacks).
+If you configure a `HeartbeatTimeout` on this activity, the external completer is responsible for sending heartbeats via the async handle.
+If you do NOT set a `HeartbeatTimeout`, no heartbeats are required.
+
+**Note:** If the external system that completes the asynchronous action can reliably be trusted to do the task and Signal back with the result, and it doesn't need to Heartbeat or receive Cancellation, then consider using **signals** instead.
+
+```csharp
+using Temporalio.Activities;
+using Temporalio.Client;
+
+[Activity]
+public async Task RequestApprovalAsync(string requestId)
+{
+    var taskToken = ActivityExecutionContext.Current.Info.TaskToken;
+
+    // Store task token for later completion (e.g., in database)
+    await StoreTaskTokenAsync(requestId, taskToken);
+
+    // Mark this activity as waiting for external completion
+    throw new CompleteAsyncException();
+}
+
+// Later, complete the activity from another process
+public async Task CompleteApprovalAsync(string requestId, bool approved)
+{
+    var client = await TemporalClient.ConnectAsync(new("localhost:7233"));
+    // Retrieve the task token from external storage (e.g., database)
+    var taskToken = await GetTaskTokenAsync(requestId);
+
+    var handle = client.GetAsyncActivityHandle(taskToken);
+
+    // Optional: if a HeartbeatTimeout was set, you can periodically:
+    // await handle.HeartbeatAsync(progressDetails);
+
+    if (approved)
+        await handle.CompleteAsync("approved");
+    else
+        // You can also fail or report cancellation via the handle
+        await handle.FailAsync(new ApplicationFailureException("Rejected"));
+}
+```
+
+## Worker Tuning
+
+Configure worker performance settings.
+
+```csharp
+var worker = new TemporalWorker(
+    client,
+    new TemporalWorkerOptions("my-task-queue")
+    {
+        // Workflow task concurrency
+        MaxConcurrentWorkflowTasks = 100,
+        // Activity task concurrency
+        MaxConcurrentActivities = 100,
+        // Graceful shutdown timeout
+        GracefulShutdownTimeout = TimeSpan.FromSeconds(30),
+    }
+    .AddWorkflow<MyWorkflow>()
+    .AddAllActivities(new MyActivities()));
+```
+
+## Workflow Init Attribute
+
+Use `[WorkflowInit]` on a constructor to run initialization code when a workflow is first created.
+
+**Purpose:** Execute some setup code before signal/update happens or run is invoked.
+
+```csharp
+[Workflow]
+public class MyWorkflow
+{
+    private readonly string _initialValue;
+    private readonly List<string> _items = new();
+
+    [WorkflowInit]
+    public MyWorkflow(string initialValue)
+    {
+        _initialValue = initialValue;
+    }
+
+    [WorkflowRun]
+    public async Task<string> RunAsync(string initialValue)
+    {
+        // _initialValue and _items are already initialized
+        return _initialValue;
+    }
+}
+```
+
+Constructor and `[WorkflowRun]` method must have the same parameters with the same types. You cannot make blocking calls (activities, sleeps, etc.) from the constructor.
+
+## Workflow Failure Exception Types
+
+Control which exceptions cause workflow failures vs workflow task retries.
+
+**Default behavior:** Only `ApplicationFailureException` fails a workflow. All other exceptions retry the workflow task forever (treated as bugs to fix with a code deployment).
+
+**Tip for testing:** Set `WorkflowFailureExceptionTypes` to include `Exception` so any unhandled exception fails the workflow immediately rather than retrying the workflow task forever. This surfaces bugs faster.
+
+### Worker-Level Configuration
+
+```csharp
+var worker = new TemporalWorker(
+    client,
+    new TemporalWorkerOptions("my-task-queue")
+    {
+        // These exception types will fail the workflow execution (not just the task)
+        WorkflowFailureExceptionTypes = new[] { typeof(ArgumentException), typeof(InvalidOperationException) },
+    }
+    .AddWorkflow<MyWorkflow>()
+    .AddAllActivities(new MyActivities()));
+```
+
+## Dependency Injection
+
+The .NET SDK supports dependency injection via the `Temporalio.Extensions.Hosting` package, which integrates with .NET's generic host.
+
+### Worker as Generic Host
+
+```csharp
+using Temporalio.Extensions.Hosting;
+
+public class Program
+{
+    public static async Task Main(string[] args)
+    {
+        var host = Host.CreateDefaultBuilder(args)
+            .ConfigureServices(ctx =>
+                ctx.
+                    AddScoped<IOrderRepository, OrderRepository>().
+                    AddHostedTemporalWorker(
+                        clientTargetHost: "localhost:7233",
+                        clientNamespace: "default",
+                        taskQueue: "my-task-queue").
+                    AddScopedActivities<MyActivities>().
+                    AddWorkflow<MyWorkflow>())
+            .Build();
+        await host.RunAsync();
+    }
+}
+```
+
+### Activity Dependency Injection
+
+As shown in the host setup above, activities can be registered with `AddScopedActivities<T>()`, `AddSingletonActivities<T>()`, or `AddTransientActivities<T>()`. Activities registered this way are created via DI, allowing constructor injection:
+
+```csharp
+public class MyActivities
+{
+    private readonly ILogger<MyActivities> _logger;
+    private readonly IOrderRepository _repository;
+
+    public MyActivities(ILogger<MyActivities> logger, IOrderRepository repository)
+    {
+        _logger = logger;
+        _repository = repository;
+    }
+
+    [Activity]
+    public async Task<Order> GetOrderAsync(string orderId)
+    {
+        _logger.LogInformation("Fetching order {OrderId}", orderId);
+        return await _repository.GetAsync(orderId);
+    }
+}
+```
+
+**Note:** Dependency injection is NOT available in workflows — workflows must be self-contained for determinism.