Support service task being first element after StartEvent.

AGENTS.md

@@ -115,6 +115,7 @@ The libraries integrate with:
 - Use internal accessibility on types by default
 - Use sealed for classes unless we consider inheritance a valid use-case
 - Use Nullable Reference Types
+- Don't use null forgiveness operator without justification
 - Remember to dispose `IDisposable`/`IAsyncDisposable` instances
 - We want to minimize external dependencies
 - For HTTP APIs we should have `...Request` and `...Response` DTOs (see `LookupPersonRequest.cs` and the corresponding response as an example)

src/Altinn.App.Api/Controllers/InstancesController.cs

@@ -334,7 +334,7 @@ public async Task<ActionResult<InstanceResponse>> Post(
 
         Instance instance;
         instanceTemplate.Process = null;
-        ProcessStateChange? change = null;
+        ProcessStateChange change;
 
         try
         {
@@ -381,9 +381,18 @@ await _instanceClient.DeleteInstance(
                 Guid.Parse(instance.Id.Split("/")[1])
             );
 
-            // notify app and store events
-            _logger.LogInformation("Events sent to process engine: {Events}", change?.Events);
-            await _processEngine.HandleEventsAndUpdateStorage(instance, null, change?.Events);
+            ProcessChangeResult startProcessResult = await _processEngine.Start(
+                instance,
+                change,
+                User,
+                language: language,
+                ct: HttpContext.RequestAborted
+            );
+
+            if (!startProcessResult.Success)
+                return Conflict(startProcessResult.ErrorMessage);
+
+            instance = startProcessResult.MutatedInstance;
         }
         catch (Exception exception)
         {
@@ -565,6 +574,9 @@ public async Task<ActionResult<InstanceResponse>> PostSimplified(
 
             processResult = await _processEngine.GenerateProcessStartEvents(request);
 
+            if (!processResult.Success)
+                return Conflict(processResult.ErrorMessage);
+
             Instance? source = null;
 
             if (isCopyRequest)
@@ -598,11 +610,20 @@ public async Task<ActionResult<InstanceResponse>> PostSimplified(
             }
 
             instance = await _instanceClient.GetInstance(instance);
-            await _processEngine.HandleEventsAndUpdateStorage(
+
+            var startProcessResult = await _processEngine.Start(
                 instance,
-                instansiationInstance.Prefill,
-                processResult.ProcessStateChange?.Events
+                processResult.ProcessStateChange,
+                User,
+                prefill: instansiationInstance.Prefill,
+                language: language,
+                ct: HttpContext.RequestAborted
             );
+
+            if (!startProcessResult.Success)
+                return Conflict(startProcessResult.ErrorMessage);
+
+            instance = startProcessResult.MutatedInstance;
         }
         catch (Exception exception)
         {
@@ -724,7 +745,21 @@ public async Task<ActionResult> CopyInstance(
 
         targetInstance = await _instanceClient.GetInstance(targetInstance);
 
-        await _processEngine.HandleEventsAndUpdateStorage(targetInstance, null, startResult.ProcessStateChange?.Events);
+        if (!startResult.Success)
+            return Conflict(startResult.ErrorMessage);
+
+        var startProcessResult = await _processEngine.Start(
+            targetInstance,
+            startResult.ProcessStateChange,
+            User,
+            language: language,
+            ct: HttpContext.RequestAborted
+        );
+
+        if (!startProcessResult.Success)
+            return Conflict(startProcessResult.ErrorMessage);
+
+        targetInstance = startProcessResult.MutatedInstance;
 
         await RegisterEvent("app.instance.created", targetInstance);
 

src/Altinn.App.Api/Controllers/ProcessController.cs

@@ -147,12 +147,20 @@ public async Task<ActionResult<AppProcessState>> StartProcess(
                 return Conflict(result.ErrorMessage);
             }
 
-            await _processEngine.HandleEventsAndUpdateStorage(instance, null, result.ProcessStateChange?.Events);
-
-            AppProcessState appProcessState = await ConvertAndAuthorizeActions(
+            var startProcessResult = await _processEngine.Start(
                 instance,
-                result.ProcessStateChange?.NewProcessState
+                result.ProcessStateChange,
+                User,
+                ct: HttpContext.RequestAborted
             );
+            if (!startProcessResult.Success)
+            {
+                return GetResultForError(startProcessResult);
+            }
+
+            instance = startProcessResult.MutatedInstance;
+
+            AppProcessState appProcessState = await ConvertAndAuthorizeActions(instance, instance.Process);
             return Ok(appProcessState);
         }
         catch (PlatformHttpException e)

src/Altinn.App.Core/Features/Telemetry/Telemetry.Processes.cs

@@ -41,6 +41,13 @@ internal void ProcessEnded(ProcessStateChange processChange)
         return activity;
     }
 
+    internal Activity? StartProcessStartExecutionActivity(Instance instance)
+    {
+        var activity = ActivitySource.StartActivity($"{Prefix}.StartExecution");
+        activity?.SetInstanceId(instance);
+        return activity;
+    }
+
     internal Activity? StartProcessNextActivity(Instance instance, string? action)
     {
         var activity = ActivitySource.StartActivity($"{Prefix}.Next");

src/Altinn.App.Core/Internal/Process/Interfaces/IProcessEngine.cs

@@ -1,3 +1,4 @@
+using System.Security.Claims;
 using Altinn.App.Core.Internal.Process.ProcessTasks.ServiceTasks;
 using Altinn.App.Core.Models.Process;
 using Altinn.Platform.Storage.Interface.Models;
@@ -35,4 +36,17 @@ Task<Instance> HandleEventsAndUpdateStorage(
         Dictionary<string, string>? prefill,
         List<InstanceEvent>? events
     );
+
+    /// <summary>
+    /// Dispatches process start events to storage and auto-runs any initial service tasks.
+    /// Call after instance creation and data storage, with the result from <see cref="GenerateProcessStartEvents"/>.
+    /// </summary>
+    Task<ProcessChangeResult> Start(
+        Instance instance,
+        ProcessStateChange processStateChange,
+        ClaimsPrincipal user,
+        Dictionary<string, string>? prefill = null,
+        string? language = null,
+        CancellationToken ct = default
+    );
 }

src/Altinn.App.Core/Internal/Process/ProcessEngine.cs

@@ -1,5 +1,6 @@
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
+using System.Security.Claims;
 using Altinn.App.Core.Extensions;
 using Altinn.App.Core.Features;
 using Altinn.App.Core.Features.Action;
@@ -149,6 +150,46 @@ out ProcessError? startEventError
         return changeResult;
     }
 
+    /// <inheritdoc/>
+    public async Task<ProcessChangeResult> Start(
+        Instance instance,
+        ProcessStateChange processStateChange,
+        ClaimsPrincipal user,
+        Dictionary<string, string>? prefill = null,
+        string? language = null,
+        CancellationToken ct = default
+    )
+    {
+        using var activity = _telemetry?.StartProcessStartExecutionActivity(instance);
+
+        // HandleEvents mutates instance in-place; we discard the DispatchToStorage
+        // return (same as callers did before this method existed).
+        bool isServiceTask = IsServiceTask(instance);
+        await HandleEventsAndUpdateStorage(instance, isServiceTask ? null : prefill, processStateChange.Events);
+
+        if (!isServiceTask)
+        {
+            var result = new ProcessChangeResult(instance) { Success = true, ProcessStateChange = processStateChange };
+            activity?.SetProcessChangeResult(result);
+            return result;
+        }
+
+        // Auto-run through initial service tasks, forwarding prefill to the first user task
+        var nextResult = await Next(
+            new ProcessNextRequest
+            {
+                Instance = instance,
+                User = user,
+                Action = null,
+                Language = language,
+                Prefill = prefill,
+            },
+            ct
+        );
+        activity?.SetProcessChangeResult(nextResult);
+        return nextResult;
+    }
+
     /// <inheritdoc/>
     public async Task<ProcessChangeResult> Next(ProcessNextRequest request, CancellationToken ct = default)
     {
@@ -196,6 +237,7 @@ public async Task<ProcessChangeResult> Next(ProcessNextRequest request, Cancella
                 Action = firstIteration ? request.Action : null,
                 ActionOnBehalfOf = firstIteration ? request.ActionOnBehalfOf : null,
                 Language = request.Language,
+                Prefill = request.Prefill,
             };
 
             result = await ProcessNext(processNextRequest, ct);
@@ -360,7 +402,7 @@ serviceTaskResult is ServiceTaskFailedResult
             }
         }
 
-        MoveToNextResult moveToNextResult = await HandleMoveToNext(instance, processNextAction);
+        MoveToNextResult moveToNextResult = await HandleMoveToNext(instance, processNextAction, request.Prefill);
 
         if (moveToNextResult.IsEndEvent)
         {
@@ -747,7 +789,11 @@ private async Task<InstanceEvent> GenerateProcessChangeEvent(string eventType, I
         return instanceEvent;
     }
 
-    private async Task<MoveToNextResult> HandleMoveToNext(Instance instance, string? action)
+    private async Task<MoveToNextResult> HandleMoveToNext(
+        Instance instance,
+        string? action,
+        Dictionary<string, string>? prefill = null
+    )
     {
         ProcessStateChange? processStateChange = await MoveProcessStateToNextAndGenerateEvents(instance, action);
 
@@ -756,7 +802,10 @@ private async Task<MoveToNextResult> HandleMoveToNext(Instance instance, string?
             return new MoveToNextResult(instance, null);
         }
 
-        instance = await HandleEventsAndUpdateStorage(instance, null, processStateChange.Events);
+        // Only apply prefill when the destination is a user task, not a service task.
+        // Service tasks can have data types too, and we don't want prefill applied to them.
+        Dictionary<string, string>? prefillForTask = IsServiceTask(instance) ? null : prefill;
+        instance = await HandleEventsAndUpdateStorage(instance, prefillForTask, processStateChange.Events);
         await _processEventDispatcher.RegisterEventWithEventsComponent(instance);
 
         return new MoveToNextResult(instance, processStateChange);

src/Altinn.App.Core/Models/Process/ProcessChangeResult.cs

@@ -13,6 +13,7 @@ public class ProcessChangeResult
     /// Gets or sets a value indicating whether the process change was successful
     /// </summary>
     [MemberNotNullWhen(true, nameof(ProcessStateChange))]
+    [MemberNotNullWhen(true, nameof(MutatedInstance))]
     [MemberNotNullWhen(false, nameof(ErrorMessage), nameof(ErrorType))]
     public bool Success { get; init; }
 

src/Altinn.App.Core/Models/Process/ProcessNextRequest.cs

@@ -32,4 +32,10 @@ public sealed record ProcessNextRequest
     /// The language the user sent with process/next (not required)
     /// </summary>
     public required string? Language { get; init; }
+
+    /// <summary>
+    /// Prefill data to apply when the next user task starts.
+    /// Used during instantiation to forward prefill past initial service tasks.
+    /// </summary>
+    public Dictionary<string, string>? Prefill { get; init; }
 }

test/Altinn.App.Api.Tests/Controllers/InstancesControllerFixture.cs

@@ -133,6 +133,7 @@ internal static InstancesControllerFixture Create(Authenticated? auth = null)
         services.AddSingleton(new Mock<IAppResources>(MockBehavior.Strict).Object);
 
         var httpContextMock = new Mock<HttpContext>(MockBehavior.Strict);
+        httpContextMock.Setup(hc => hc.RequestAborted).Returns(CancellationToken.None);
         services.AddTransient(_ => httpContextMock.Object);
 
         services.AddTransient<InternalPatchService>();