feat: wire SQLite replication between site nodes and fix ConfigurationDatabase tests

Add SiteReplicationActor (runs on every site node) to replicate deployed
configs and store-and-forward buffer operations to the standby peer via
cluster member discovery and fire-and-forget Tell. Wire ReplicationService
handler and pass replication actor to DeploymentManagerActor singleton.

Fix 5 pre-existing ConfigurationDatabase test failures: RowVersion NOT NULL
on SQLite, stale migration name assertion, and seed data count mismatch.

src/ScadaLink.CLI/Commands/ExternalSystemCommands.cs

@@ -15,6 +15,7 @@ public static class ExternalSystemCommands
         command.Add(BuildCreate(contactPointsOption, formatOption));
         command.Add(BuildUpdate(contactPointsOption, formatOption));
         command.Add(BuildDelete(contactPointsOption, formatOption));
+        command.Add(BuildMethodGroup(contactPointsOption, formatOption));
 
         return command;
     }
@@ -110,4 +111,121 @@ public static class ExternalSystemCommands
         });
         return cmd;
     }
+
+    // ── Method subcommands ──
+
+    private static Command BuildMethodGroup(Option<string> contactPointsOption, Option<string> formatOption)
+    {
+        var group = new Command("method") { Description = "Manage external system methods" };
+        group.Add(BuildMethodList(contactPointsOption, formatOption));
+        group.Add(BuildMethodGet(contactPointsOption, formatOption));
+        group.Add(BuildMethodCreate(contactPointsOption, formatOption));
+        group.Add(BuildMethodUpdate(contactPointsOption, formatOption));
+        group.Add(BuildMethodDelete(contactPointsOption, formatOption));
+        return group;
+    }
+
+    private static Command BuildMethodList(Option<string> contactPointsOption, Option<string> formatOption)
+    {
+        var sysIdOption = new Option<int>("--external-system-id") { Description = "External system ID", Required = true };
+        var cmd = new Command("list") { Description = "List methods for an external system" };
+        cmd.Add(sysIdOption);
+        cmd.SetAction(async (ParseResult result) =>
+        {
+            return await CommandHelpers.ExecuteCommandAsync(
+                result, contactPointsOption, formatOption,
+                new ListExternalSystemMethodsCommand(result.GetValue(sysIdOption)));
+        });
+        return cmd;
+    }
+
+    private static Command BuildMethodGet(Option<string> contactPointsOption, Option<string> formatOption)
+    {
+        var idOption = new Option<int>("--id") { Description = "Method ID", Required = true };
+        var cmd = new Command("get") { Description = "Get an external system method by ID" };
+        cmd.Add(idOption);
+        cmd.SetAction(async (ParseResult result) =>
+        {
+            return await CommandHelpers.ExecuteCommandAsync(
+                result, contactPointsOption, formatOption,
+                new GetExternalSystemMethodCommand(result.GetValue(idOption)));
+        });
+        return cmd;
+    }
+
+    private static Command BuildMethodCreate(Option<string> contactPointsOption, Option<string> formatOption)
+    {
+        var sysIdOption = new Option<int>("--external-system-id") { Description = "External system ID", Required = true };
+        var nameOption = new Option<string>("--name") { Description = "Method name", Required = true };
+        var httpMethodOption = new Option<string>("--http-method") { Description = "HTTP method (GET, POST, PUT, DELETE)", Required = true };
+        var pathOption = new Option<string>("--path") { Description = "URL path (e.g. /api/Add)", Required = true };
+        var paramsOption = new Option<string?>("--params") { Description = "Parameter definitions JSON" };
+        var returnOption = new Option<string?>("--return") { Description = "Return definition JSON" };
+
+        var cmd = new Command("create") { Description = "Create an external system method" };
+        cmd.Add(sysIdOption);
+        cmd.Add(nameOption);
+        cmd.Add(httpMethodOption);
+        cmd.Add(pathOption);
+        cmd.Add(paramsOption);
+        cmd.Add(returnOption);
+        cmd.SetAction(async (ParseResult result) =>
+        {
+            return await CommandHelpers.ExecuteCommandAsync(
+                result, contactPointsOption, formatOption,
+                new CreateExternalSystemMethodCommand(
+                    result.GetValue(sysIdOption),
+                    result.GetValue(nameOption)!,
+                    result.GetValue(httpMethodOption)!,
+                    result.GetValue(pathOption)!,
+                    result.GetValue(paramsOption),
+                    result.GetValue(returnOption)));
+        });
+        return cmd;
+    }
+
+    private static Command BuildMethodUpdate(Option<string> contactPointsOption, Option<string> formatOption)
+    {
+        var idOption = new Option<int>("--id") { Description = "Method ID", Required = true };
+        var nameOption = new Option<string?>("--name") { Description = "Method name" };
+        var httpMethodOption = new Option<string?>("--http-method") { Description = "HTTP method" };
+        var pathOption = new Option<string?>("--path") { Description = "URL path" };
+        var paramsOption = new Option<string?>("--params") { Description = "Parameter definitions JSON" };
+        var returnOption = new Option<string?>("--return") { Description = "Return definition JSON" };
+
+        var cmd = new Command("update") { Description = "Update an external system method" };
+        cmd.Add(idOption);
+        cmd.Add(nameOption);
+        cmd.Add(httpMethodOption);
+        cmd.Add(pathOption);
+        cmd.Add(paramsOption);
+        cmd.Add(returnOption);
+        cmd.SetAction(async (ParseResult result) =>
+        {
+            return await CommandHelpers.ExecuteCommandAsync(
+                result, contactPointsOption, formatOption,
+                new UpdateExternalSystemMethodCommand(
+                    result.GetValue(idOption),
+                    result.GetValue(nameOption),
+                    result.GetValue(httpMethodOption),
+                    result.GetValue(pathOption),
+                    result.GetValue(paramsOption),
+                    result.GetValue(returnOption)));
+        });
+        return cmd;
+    }
+
+    private static Command BuildMethodDelete(Option<string> contactPointsOption, Option<string> formatOption)
+    {
+        var idOption = new Option<int>("--id") { Description = "Method ID", Required = true };
+        var cmd = new Command("delete") { Description = "Delete an external system method" };
+        cmd.Add(idOption);
+        cmd.SetAction(async (ParseResult result) =>
+        {
+            return await CommandHelpers.ExecuteCommandAsync(
+                result, contactPointsOption, formatOption,
+                new DeleteExternalSystemMethodCommand(result.GetValue(idOption)));
+        });
+        return cmd;
+    }
 }

src/ScadaLink.CLI/Commands/TemplateCommands.cs

@@ -300,6 +300,9 @@ public static class TemplateCommands
         var lockedOption = new Option<bool>("--locked") { Description = "Lock status" };
         lockedOption.DefaultValueFactory = _ => false;
 
+        var paramsOption = new Option<string?>("--parameters") { Description = "Parameter definitions JSON" };
+        var returnOption = new Option<string?>("--return-def") { Description = "Return definition JSON" };
+
         var addCmd = new Command("add") { Description = "Add a script to a template" };
         addCmd.Add(templateIdOption);
         addCmd.Add(nameOption);
@@ -307,6 +310,8 @@ public static class TemplateCommands
         addCmd.Add(triggerTypeOption);
         addCmd.Add(triggerConfigOption);
         addCmd.Add(lockedOption);
+        addCmd.Add(paramsOption);
+        addCmd.Add(returnOption);
         addCmd.SetAction(async (ParseResult result) =>
         {
             return await CommandHelpers.ExecuteCommandAsync(
@@ -317,7 +322,9 @@ public static class TemplateCommands
                     result.GetValue(codeOption)!,
                     result.GetValue(triggerTypeOption)!,
                     result.GetValue(triggerConfigOption),
-                    result.GetValue(lockedOption)));
+                    result.GetValue(lockedOption),
+                    result.GetValue(paramsOption),
+                    result.GetValue(returnOption)));
         });
         group.Add(addCmd);
 
@@ -329,6 +336,9 @@ public static class TemplateCommands
         var updateLockedOption = new Option<bool>("--locked") { Description = "Lock status" };
         updateLockedOption.DefaultValueFactory = _ => false;
 
+        var updateParamsOption = new Option<string?>("--parameters") { Description = "Parameter definitions JSON" };
+        var updateReturnOption = new Option<string?>("--return-def") { Description = "Return definition JSON" };
+
         var updateCmd = new Command("update") { Description = "Update a template script" };
         updateCmd.Add(updateIdOption);
         updateCmd.Add(updateNameOption);
@@ -336,6 +346,8 @@ public static class TemplateCommands
         updateCmd.Add(updateTriggerTypeOption);
         updateCmd.Add(updateTriggerConfigOption);
         updateCmd.Add(updateLockedOption);
+        updateCmd.Add(updateParamsOption);
+        updateCmd.Add(updateReturnOption);
         updateCmd.SetAction(async (ParseResult result) =>
         {
             return await CommandHelpers.ExecuteCommandAsync(
@@ -346,7 +358,9 @@ public static class TemplateCommands
                     result.GetValue(updateCodeOption)!,
                     result.GetValue(updateTriggerTypeOption)!,
                     result.GetValue(updateTriggerConfigOption),
-                    result.GetValue(updateLockedOption)));
+                    result.GetValue(updateLockedOption),
+                    result.GetValue(updateParamsOption),
+                    result.GetValue(updateReturnOption)));
         });
         group.Add(updateCmd);
 

src/ScadaLink.CentralUI/Components/Pages/Deployment/DebugView.razor

@@ -11,15 +11,11 @@
 @inject ITemplateEngineRepository TemplateEngineRepository
 @inject ISiteRepository SiteRepository
 @inject CommunicationService CommunicationService
+@inject IJSRuntime JS
 @implements IDisposable
 
 <div class="container-fluid mt-3">
-    <div class="d-flex justify-content-between align-items-center mb-3">
-        <h4 class="mb-0">Debug View</h4>
-        <div class="alert alert-info py-1 px-2 mb-0 small">
-            Debug view streams are lost on failover. Re-open if connection drops.
-        </div>
-    </div>
+    <h4 class="mb-3">Debug View</h4>
 
     <ToastNotification @ref="_toast" />
 
@@ -182,6 +178,24 @@
         _loading = false;
     }
 
+    protected override async Task OnAfterRenderAsync(bool firstRender)
+    {
+        if (!firstRender) return;
+
+        var storedSiteId = await JS.InvokeAsync<string>("localStorage.getItem", "debugView.siteId");
+        var storedInstanceName = await JS.InvokeAsync<string>("localStorage.getItem", "debugView.instanceName");
+
+        if (!string.IsNullOrEmpty(storedSiteId) && int.TryParse(storedSiteId, out var siteId)
+            && !string.IsNullOrEmpty(storedInstanceName))
+        {
+            _selectedSiteId = siteId;
+            await LoadInstancesForSite();
+            _selectedInstanceName = storedInstanceName;
+            StateHasChanged();
+            await Connect();
+        }
+    }
+
     private async Task LoadInstancesForSite()
     {
         _siteInstances.Clear();
@@ -224,6 +238,12 @@
             }
 
             _connected = true;
+
+            // Persist selection to localStorage for auto-reconnect on refresh
+            await JS.InvokeVoidAsync("localStorage.setItem", "debugView.siteId", _selectedSiteId.ToString());
+            await JS.InvokeVoidAsync("localStorage.setItem", "debugView.instanceName", _selectedInstanceName);
+            await JS.InvokeVoidAsync("localStorage.setItem", "debugView.siteIdentifier", site.SiteIdentifier);
+
             _toast.ShowSuccess($"Connected to {_selectedInstanceName}");
 
             // Periodic refresh (simulating SignalR push by re-subscribing)
@@ -253,7 +273,7 @@
         _connecting = false;
     }
 
-    private void Disconnect()
+    private async Task Disconnect()
     {
         _refreshTimer?.Dispose();
         _refreshTimer = null;
@@ -268,6 +288,11 @@
             }
         }
 
+        // Clear persisted selection — user explicitly disconnected
+        await JS.InvokeVoidAsync("localStorage.removeItem", "debugView.siteId");
+        await JS.InvokeVoidAsync("localStorage.removeItem", "debugView.instanceName");
+        await JS.InvokeVoidAsync("localStorage.removeItem", "debugView.siteIdentifier");
+
         _connected = false;
         _snapshot = null;
         _attributeValues.Clear();

src/ScadaLink.CentralUI/_Imports.razor

@@ -4,6 +4,7 @@
 @using Microsoft.AspNetCore.Components.Forms
 @using Microsoft.AspNetCore.Components.Routing
 @using Microsoft.AspNetCore.Components.Web
+@using Microsoft.JSInterop
 @using static Microsoft.AspNetCore.Components.Web.RenderMode
 @using ScadaLink.CentralUI
 @using ScadaLink.CentralUI.Components.Layout

src/ScadaLink.Commons/Interfaces/Services/IExternalSystemClient.cs

@@ -1,3 +1,5 @@
+using ScadaLink.Commons.Types;
+
 namespace ScadaLink.Commons.Interfaces.Services;
 
 /// <summary>
@@ -34,4 +36,27 @@ public record ExternalCallResult(
     bool Success,
     string? ResponseJson,
     string? ErrorMessage,
-    bool WasBuffered = false);
+    bool WasBuffered = false)
+{
+    private dynamic? _response;
+    private bool _responseParsed;
+
+    /// <summary>
+    /// Parsed response as a dynamic object. Returns null if ResponseJson is null or empty.
+    /// Access properties directly: result.Response.result, result.Response.items[0].name, etc.
+    /// </summary>
+    public dynamic? Response
+    {
+        get
+        {
+            if (!_responseParsed)
+            {
+                _response = string.IsNullOrEmpty(ResponseJson)
+                    ? null
+                    : new DynamicJsonElement(System.Text.Json.JsonDocument.Parse(ResponseJson).RootElement);
+                _responseParsed = true;
+            }
+            return _response;
+        }
+    }
+}

src/ScadaLink.Commons/Messages/Management/ExternalSystemCommands.cs

@@ -5,3 +5,10 @@ public record GetExternalSystemCommand(int ExternalSystemId);
 public record CreateExternalSystemCommand(string Name, string EndpointUrl, string AuthType, string? AuthConfiguration);
 public record UpdateExternalSystemCommand(int ExternalSystemId, string Name, string EndpointUrl, string AuthType, string? AuthConfiguration);
 public record DeleteExternalSystemCommand(int ExternalSystemId);
+
+// External System Methods
+public record ListExternalSystemMethodsCommand(int ExternalSystemId);
+public record GetExternalSystemMethodCommand(int MethodId);
+public record CreateExternalSystemMethodCommand(int ExternalSystemId, string Name, string HttpMethod, string Path, string? ParameterDefinitions = null, string? ReturnDefinition = null);
+public record UpdateExternalSystemMethodCommand(int MethodId, string? Name = null, string? HttpMethod = null, string? Path = null, string? ParameterDefinitions = null, string? ReturnDefinition = null);
+public record DeleteExternalSystemMethodCommand(int MethodId);

src/ScadaLink.Commons/Messages/Management/TemplateCommands.cs

@@ -14,8 +14,8 @@ public record DeleteTemplateAttributeCommand(int AttributeId);
 public record AddTemplateAlarmCommand(int TemplateId, string Name, string TriggerType, int PriorityLevel, string? Description, string? TriggerConfiguration, bool IsLocked);
 public record UpdateTemplateAlarmCommand(int AlarmId, string Name, string TriggerType, int PriorityLevel, string? Description, string? TriggerConfiguration, bool IsLocked);
 public record DeleteTemplateAlarmCommand(int AlarmId);
-public record AddTemplateScriptCommand(int TemplateId, string Name, string Code, string? TriggerType, string? TriggerConfiguration, bool IsLocked);
-public record UpdateTemplateScriptCommand(int ScriptId, string Name, string Code, string? TriggerType, string? TriggerConfiguration, bool IsLocked);
+public record AddTemplateScriptCommand(int TemplateId, string Name, string Code, string? TriggerType, string? TriggerConfiguration, bool IsLocked, string? ParameterDefinitions = null, string? ReturnDefinition = null);
+public record UpdateTemplateScriptCommand(int ScriptId, string Name, string Code, string? TriggerType, string? TriggerConfiguration, bool IsLocked, string? ParameterDefinitions = null, string? ReturnDefinition = null);
 public record DeleteTemplateScriptCommand(int ScriptId);
 public record AddTemplateCompositionCommand(int TemplateId, string InstanceName, int ComposedTemplateId);
 public record DeleteTemplateCompositionCommand(int CompositionId);

src/ScadaLink.Commons/Types/DynamicJsonElement.cs

@@ -0,0 +1,92 @@
+using System.Dynamic;
+using System.Text.Json;
+
+namespace ScadaLink.Commons.Types;
+
+/// <summary>
+/// Wraps a JsonElement as a dynamic object for convenient property access in scripts.
+/// Supports property access (obj.name), indexing (obj.items[0]), and ToString().
+/// </summary>
+public class DynamicJsonElement : DynamicObject
+{
+    private readonly JsonElement _element;
+
+    public DynamicJsonElement(JsonElement element)
+    {
+        _element = element;
+    }
+
+    public override bool TryGetMember(GetMemberBinder binder, out object? result)
+    {
+        if (_element.ValueKind == JsonValueKind.Object &&
+            _element.TryGetProperty(binder.Name, out var prop))
+        {
+            result = Wrap(prop);
+            return true;
+        }
+        result = null;
+        return false;
+    }
+
+    public override bool TryGetIndex(GetIndexBinder binder, object[] indexes, out object? result)
+    {
+        if (_element.ValueKind == JsonValueKind.Array &&
+            indexes.Length == 1 && indexes[0] is int index)
+        {
+            var arrayLength = _element.GetArrayLength();
+            if (index >= 0 && index < arrayLength)
+            {
+                result = Wrap(_element[index]);
+                return true;
+            }
+        }
+        result = null;
+        return false;
+    }
+
+    public override bool TryConvert(ConvertBinder binder, out object? result)
+    {
+        result = ConvertTo(binder.Type);
+        return result != null || binder.Type == typeof(object);
+    }
+
+    public override string ToString()
+    {
+        return _element.ValueKind switch
+        {
+            JsonValueKind.String => _element.GetString() ?? "",
+            JsonValueKind.Number => _element.GetRawText(),
+            JsonValueKind.True => "true",
+            JsonValueKind.False => "false",
+            JsonValueKind.Null => "",
+            _ => _element.GetRawText()
+        };
+    }
+
+    private object? ConvertTo(Type type)
+    {
+        if (type == typeof(string)) return ToString();
+        if (type == typeof(int) && _element.ValueKind == JsonValueKind.Number) return _element.GetInt32();
+        if (type == typeof(long) && _element.ValueKind == JsonValueKind.Number) return _element.GetInt64();
+        if (type == typeof(double) && _element.ValueKind == JsonValueKind.Number) return _element.GetDouble();
+        if (type == typeof(decimal) && _element.ValueKind == JsonValueKind.Number) return _element.GetDecimal();
+        if (type == typeof(bool) && (_element.ValueKind == JsonValueKind.True || _element.ValueKind == JsonValueKind.False))
+            return _element.GetBoolean();
+        return null;
+    }
+
+    private static object? Wrap(JsonElement element)
+    {
+        return element.ValueKind switch
+        {
+            JsonValueKind.Object => new DynamicJsonElement(element),
+            JsonValueKind.Array => new DynamicJsonElement(element),
+            JsonValueKind.String => element.GetString(),
+            JsonValueKind.Number => element.TryGetInt64(out var l) ? l : element.GetDouble(),
+            JsonValueKind.True => true,
+            JsonValueKind.False => false,
+            JsonValueKind.Null => null,
+            _ => element.GetRawText()
+        };
+    }
+}

src/ScadaLink.Commons/Types/Flattening/ValidationResult.cs

@@ -60,5 +60,6 @@ public enum ValidationCategory
     ReturnTypeMismatch,
     TriggerOperandType,
     OnTriggerScriptNotFound,
-    CrossCallViolation
+    CrossCallViolation,
+    MissingMetadata
 }

src/ScadaLink.DeploymentManager/FlatteningPipeline.cs

@@ -83,8 +83,18 @@ public class FlatteningPipeline : IFlatteningPipeline
 
         var config = flattenResult.Value;
 
+        // Load shared scripts for semantic validation
+        var sharedScriptEntities = await _templateRepo.GetAllSharedScriptsAsync(cancellationToken);
+        var resolvedSharedScripts = sharedScriptEntities.Select(s => new ResolvedScript
+        {
+            CanonicalName = s.Name,
+            Code = s.Code,
+            ParameterDefinitions = s.ParameterDefinitions,
+            ReturnDefinition = s.ReturnDefinition
+        }).ToList();
+
         // Validate
-        var validation = _validationService.Validate(config);
+        var validation = _validationService.Validate(config, resolvedSharedScripts);
 
         // Compute revision hash
         var hash = _revisionHashService.ComputeHash(config);

src/ScadaLink.Host/Actors/AkkaHostedService.cs

@@ -11,9 +11,11 @@ using ScadaLink.Communication.Actors;
 using ScadaLink.Host.Actors;
 using ScadaLink.SiteRuntime;
 using ScadaLink.SiteRuntime.Actors;
+using ScadaLink.SiteRuntime.Messages;
 using ScadaLink.SiteRuntime.Persistence;
 using ScadaLink.SiteRuntime.Scripts;
 using ScadaLink.SiteRuntime.Streaming;
+using ScadaLink.StoreAndForward;
 
 namespace ScadaLink.Host.Actors;
 
@@ -231,6 +233,26 @@ akka {{
         // Resolve the health collector for the Deployment Manager
         var siteHealthCollector = _serviceProvider.GetService<ScadaLink.HealthMonitoring.ISiteHealthCollector>();
 
+        // Create SiteReplicationActor on every node (not a singleton)
+        var sfStorage = _serviceProvider.GetRequiredService<StoreAndForwardStorage>();
+        var replicationService = _serviceProvider.GetRequiredService<ReplicationService>();
+        var replicationLogger = _serviceProvider.GetRequiredService<ILoggerFactory>()
+            .CreateLogger<SiteReplicationActor>();
+
+        var replicationActor = _actorSystem!.ActorOf(
+            Props.Create(() => new SiteReplicationActor(
+                storage, sfStorage, replicationService, siteRole, replicationLogger)),
+            "site-replication");
+
+        // Wire S&F replication handler to forward operations via the replication actor
+        replicationService.SetReplicationHandler(op =>
+        {
+            replicationActor.Tell(new ReplicateStoreAndForward(op));
+            return Task.CompletedTask;
+        });
+
+        _logger.LogInformation("SiteReplicationActor created and S&F replication handler wired");
+
         // Create the Deployment Manager as a cluster singleton
         var singletonProps = ClusterSingletonManager.Props(
             singletonProps: Props.Create(() => new DeploymentManagerActor(
@@ -241,6 +263,7 @@ akka {{
                 siteRuntimeOptionsValue,
                 dmLogger,
                 dclManager,
+                replicationActor,
                 siteHealthCollector,
                 _serviceProvider)),
             terminationMessage: PoisonPill.Instance,
@@ -267,6 +290,9 @@ akka {{
                 dmProxy)),
             "site-communication");
 
+        // Register local handlers with SiteCommunicationActor
+        siteCommActor.Tell(new RegisterLocalHandler(LocalHandlerType.Artifacts, dmProxy));
+
         // Register SiteCommunicationActor with ClusterClientReceptionist so central ClusterClients can reach it
         ClusterClientReceptionist.Get(_actorSystem).RegisterService(siteCommActor);
 

src/ScadaLink.ManagementService/ManagementActor.cs

@@ -90,6 +90,8 @@ public class ManagementActor : ReceiveActor
             or ValidateTemplateCommand
             or CreateExternalSystemCommand or UpdateExternalSystemCommand
             or DeleteExternalSystemCommand
+            or CreateExternalSystemMethodCommand or UpdateExternalSystemMethodCommand
+            or DeleteExternalSystemMethodCommand
             or CreateNotificationListCommand or UpdateNotificationListCommand
             or DeleteNotificationListCommand
             or UpdateSmtpConfigCommand
@@ -178,6 +180,11 @@ public class ManagementActor : ReceiveActor
             CreateExternalSystemCommand cmd => await HandleCreateExternalSystem(sp, cmd),
             UpdateExternalSystemCommand cmd => await HandleUpdateExternalSystem(sp, cmd),
             DeleteExternalSystemCommand cmd => await HandleDeleteExternalSystem(sp, cmd),
+            ListExternalSystemMethodsCommand cmd => await HandleListExternalSystemMethods(sp, cmd),
+            GetExternalSystemMethodCommand cmd => await HandleGetExternalSystemMethod(sp, cmd),
+            CreateExternalSystemMethodCommand cmd => await HandleCreateExternalSystemMethod(sp, cmd),
+            UpdateExternalSystemMethodCommand cmd => await HandleUpdateExternalSystemMethod(sp, cmd),
+            DeleteExternalSystemMethodCommand cmd => await HandleDeleteExternalSystemMethod(sp, cmd),
 
             // Notification Lists
             ListNotificationListsCommand => await HandleListNotificationLists(sp),
@@ -568,6 +575,55 @@ public class ManagementActor : ReceiveActor
         return true;
     }
 
+    private static async Task<object?> HandleListExternalSystemMethods(IServiceProvider sp, ListExternalSystemMethodsCommand cmd)
+    {
+        var repo = sp.GetRequiredService<IExternalSystemRepository>();
+        return await repo.GetMethodsByExternalSystemIdAsync(cmd.ExternalSystemId);
+    }
+
+    private static async Task<object?> HandleGetExternalSystemMethod(IServiceProvider sp, GetExternalSystemMethodCommand cmd)
+    {
+        var repo = sp.GetRequiredService<IExternalSystemRepository>();
+        return await repo.GetExternalSystemMethodByIdAsync(cmd.MethodId);
+    }
+
+    private static async Task<object?> HandleCreateExternalSystemMethod(IServiceProvider sp, CreateExternalSystemMethodCommand cmd)
+    {
+        var repo = sp.GetRequiredService<IExternalSystemRepository>();
+        var method = new ExternalSystemMethod(cmd.Name, cmd.HttpMethod, cmd.Path)
+        {
+            ExternalSystemDefinitionId = cmd.ExternalSystemId,
+            ParameterDefinitions = cmd.ParameterDefinitions,
+            ReturnDefinition = cmd.ReturnDefinition
+        };
+        await repo.AddExternalSystemMethodAsync(method);
+        await repo.SaveChangesAsync();
+        return method;
+    }
+
+    private static async Task<object?> HandleUpdateExternalSystemMethod(IServiceProvider sp, UpdateExternalSystemMethodCommand cmd)
+    {
+        var repo = sp.GetRequiredService<IExternalSystemRepository>();
+        var method = await repo.GetExternalSystemMethodByIdAsync(cmd.MethodId)
+            ?? throw new InvalidOperationException($"ExternalSystemMethod with ID {cmd.MethodId} not found.");
+        if (cmd.Name != null) method.Name = cmd.Name;
+        if (cmd.HttpMethod != null) method.HttpMethod = cmd.HttpMethod;
+        if (cmd.Path != null) method.Path = cmd.Path;
+        if (cmd.ParameterDefinitions != null) method.ParameterDefinitions = cmd.ParameterDefinitions;
+        if (cmd.ReturnDefinition != null) method.ReturnDefinition = cmd.ReturnDefinition;
+        await repo.UpdateExternalSystemMethodAsync(method);
+        await repo.SaveChangesAsync();
+        return method;
+    }
+
+    private static async Task<object?> HandleDeleteExternalSystemMethod(IServiceProvider sp, DeleteExternalSystemMethodCommand cmd)
+    {
+        var repo = sp.GetRequiredService<IExternalSystemRepository>();
+        await repo.DeleteExternalSystemMethodAsync(cmd.MethodId);
+        await repo.SaveChangesAsync();
+        return true;
+    }
+
     // ========================================================================
     // Notification handlers
     // ========================================================================
@@ -850,7 +906,9 @@ public class ManagementActor : ReceiveActor
         {
             TriggerType = cmd.TriggerType,
             TriggerConfiguration = cmd.TriggerConfiguration,
-            IsLocked = cmd.IsLocked
+            IsLocked = cmd.IsLocked,
+            ParameterDefinitions = cmd.ParameterDefinitions,
+            ReturnDefinition = cmd.ReturnDefinition
         };
         var result = await svc.AddScriptAsync(cmd.TemplateId, script, user);
         return result.IsSuccess ? result.Value : throw new InvalidOperationException(result.Error);
@@ -863,7 +921,9 @@ public class ManagementActor : ReceiveActor
         {
             TriggerType = cmd.TriggerType,
             TriggerConfiguration = cmd.TriggerConfiguration,
-            IsLocked = cmd.IsLocked
+            IsLocked = cmd.IsLocked,
+            ParameterDefinitions = cmd.ParameterDefinitions,
+            ReturnDefinition = cmd.ReturnDefinition
         };
         var result = await svc.UpdateScriptAsync(cmd.ScriptId, script, user);
         return result.IsSuccess ? result.Value : throw new InvalidOperationException(result.Error);

src/ScadaLink.SiteRuntime/Actors/DeploymentManagerActor.cs

@@ -6,6 +6,7 @@ using ScadaLink.Commons.Messages.Deployment;
 using ScadaLink.Commons.Messages.Lifecycle;
 using ScadaLink.Commons.Types.Enums;
 using ScadaLink.HealthMonitoring;
+using ScadaLink.SiteRuntime.Messages;
 using ScadaLink.SiteRuntime.Persistence;
 using ScadaLink.SiteRuntime.Scripts;
 using ScadaLink.SiteRuntime.Streaming;
@@ -31,6 +32,7 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
     private readonly SiteRuntimeOptions _options;
     private readonly ILogger<DeploymentManagerActor> _logger;
     private readonly IActorRef? _dclManager;
+    private readonly IActorRef? _replicationActor;
     private readonly ISiteHealthCollector? _healthCollector;
     private readonly IServiceProvider? _serviceProvider;
     private readonly Dictionary<string, IActorRef> _instanceActors = new();
@@ -46,6 +48,7 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
         SiteRuntimeOptions options,
         ILogger<DeploymentManagerActor> logger,
         IActorRef? dclManager = null,
+        IActorRef? replicationActor = null,
         ISiteHealthCollector? healthCollector = null,
         IServiceProvider? serviceProvider = null)
     {
@@ -55,6 +58,7 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
         _streamManager = streamManager;
         _options = options;
         _dclManager = dclManager;
+        _replicationActor = replicationActor;
         _healthCollector = healthCollector;
         _serviceProvider = serviceProvider;
         _logger = logger;
@@ -238,6 +242,11 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
             // Static overrides are reset on redeployment per design decision
             await _storage.ClearStaticOverridesAsync(instanceName);
 
+            // Replicate to standby node
+            _replicationActor?.Tell(new ReplicateConfigDeploy(
+                instanceName, command.FlattenedConfigurationJson,
+                command.DeploymentId, command.RevisionHash, true));
+
             return new DeployPersistenceResult(command.DeploymentId, instanceName, true, null, sender);
         }).ContinueWith(t =>
         {
@@ -285,6 +294,9 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
         var sender = Sender;
         _storage.SetInstanceEnabledAsync(instanceName, false).ContinueWith(t =>
         {
+            if (t.IsCompletedSuccessfully)
+                _replicationActor?.Tell(new ReplicateConfigSetEnabled(instanceName, false));
+
             return new InstanceLifecycleResponse(
                 command.CommandId,
                 instanceName,
@@ -308,6 +320,7 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
         Task.Run(async () =>
         {
             await _storage.SetInstanceEnabledAsync(instanceName, true);
+            _replicationActor?.Tell(new ReplicateConfigSetEnabled(instanceName, true));
             var configs = await _storage.GetAllDeployedConfigsAsync();
             var config = configs.FirstOrDefault(c => c.InstanceUniqueName == instanceName);
             return new EnableResult(command, config, null, sender);
@@ -365,6 +378,9 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
         var sender = Sender;
         _storage.RemoveDeployedConfigAsync(instanceName).ContinueWith(t =>
         {
+            if (t.IsCompletedSuccessfully)
+                _replicationActor?.Tell(new ReplicateConfigRemove(instanceName));
+
             return new InstanceLifecycleResponse(
                 command.CommandId,
                 instanceName,
@@ -548,6 +564,9 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
                     }
                 }
 
+                // Replicate artifacts to standby node
+                _replicationActor?.Tell(new ReplicateArtifacts(command));
+
                 return new ArtifactDeploymentResponse(
                     command.DeploymentId, "", true, null, DateTimeOffset.UtcNow);
             }

src/ScadaLink.SiteRuntime/Actors/ScriptActor.cs

@@ -261,6 +261,7 @@ public class ScriptActor : ReceiveActor, IWithTimers
             "interval" => ParseIntervalTrigger(triggerConfigJson),
             "valuechange" => ParseValueChangeTrigger(triggerConfigJson),
             "conditional" => ParseConditionalTrigger(triggerConfigJson),
+            "call" => null, // No automatic trigger — invoked only via Instance.CallScript()
             _ => null
         };
     }

src/ScadaLink.SiteRuntime/Actors/SiteReplicationActor.cs

@@ -0,0 +1,214 @@
+using Akka.Actor;
+using Akka.Cluster;
+using Akka.Event;
+using Microsoft.Extensions.Logging;
+using ScadaLink.SiteRuntime.Messages;
+using ScadaLink.SiteRuntime.Persistence;
+using ScadaLink.StoreAndForward;
+
+namespace ScadaLink.SiteRuntime.Actors;
+
+/// <summary>
+/// Runs on every site node (not a singleton). Handles both config and S&amp;F replication
+/// between site cluster peers.
+///
+/// Outbound: receives local replication requests and forwards to peer via ActorSelection.
+/// Inbound: receives replicated operations from peer and applies to local SQLite.
+/// Uses fire-and-forget (Tell) — no ack wait per design.
+/// </summary>
+public class SiteReplicationActor : ReceiveActor
+{
+    private readonly SiteStorageService _storage;
+    private readonly StoreAndForwardStorage _sfStorage;
+    private readonly ReplicationService _replicationService;
+    private readonly string _siteRole;
+    private readonly ILogger<SiteReplicationActor> _logger;
+    private readonly Cluster _cluster;
+    private Address? _peerAddress;
+
+    public SiteReplicationActor(
+        SiteStorageService storage,
+        StoreAndForwardStorage sfStorage,
+        ReplicationService replicationService,
+        string siteRole,
+        ILogger<SiteReplicationActor> logger)
+    {
+        _storage = storage;
+        _sfStorage = sfStorage;
+        _replicationService = replicationService;
+        _siteRole = siteRole;
+        _logger = logger;
+        _cluster = Cluster.Get(Context.System);
+
+        // Cluster member events
+        Receive<ClusterEvent.MemberUp>(HandleMemberUp);
+        Receive<ClusterEvent.MemberRemoved>(HandleMemberRemoved);
+        Receive<ClusterEvent.CurrentClusterState>(HandleCurrentClusterState);
+
+        // Outbound — forward to peer
+        Receive<ReplicateConfigDeploy>(msg => SendToPeer(new ApplyConfigDeploy(
+            msg.InstanceName, msg.ConfigJson, msg.DeploymentId, msg.RevisionHash, msg.IsEnabled)));
+        Receive<ReplicateConfigRemove>(msg => SendToPeer(new ApplyConfigRemove(msg.InstanceName)));
+        Receive<ReplicateConfigSetEnabled>(msg => SendToPeer(new ApplyConfigSetEnabled(
+            msg.InstanceName, msg.IsEnabled)));
+        Receive<ReplicateArtifacts>(msg => SendToPeer(new ApplyArtifacts(msg.Command)));
+        Receive<ReplicateStoreAndForward>(msg => SendToPeer(new ApplyStoreAndForward(msg.Operation)));
+
+        // Inbound — apply from peer
+        Receive<ApplyConfigDeploy>(HandleApplyConfigDeploy);
+        Receive<ApplyConfigRemove>(HandleApplyConfigRemove);
+        Receive<ApplyConfigSetEnabled>(HandleApplyConfigSetEnabled);
+        Receive<ApplyArtifacts>(HandleApplyArtifacts);
+        Receive<ApplyStoreAndForward>(HandleApplyStoreAndForward);
+    }
+
+    protected override void PreStart()
+    {
+        base.PreStart();
+        _cluster.Subscribe(Self, ClusterEvent.SubscriptionInitialStateMode.InitialStateAsSnapshot,
+            typeof(ClusterEvent.MemberUp),
+            typeof(ClusterEvent.MemberRemoved));
+        _logger.LogInformation("SiteReplicationActor started, subscribing to cluster events for role {Role}", _siteRole);
+    }
+
+    protected override void PostStop()
+    {
+        _cluster.Unsubscribe(Self);
+        base.PostStop();
+    }
+
+    private void HandleCurrentClusterState(ClusterEvent.CurrentClusterState state)
+    {
+        foreach (var member in state.Members)
+        {
+            if (member.Status == MemberStatus.Up)
+                TryTrackPeer(member);
+        }
+    }
+
+    private void HandleMemberUp(ClusterEvent.MemberUp evt)
+    {
+        TryTrackPeer(evt.Member);
+    }
+
+    private void HandleMemberRemoved(ClusterEvent.MemberRemoved evt)
+    {
+        if (evt.Member.Address.Equals(_peerAddress))
+        {
+            _logger.LogInformation("Peer node removed: {Address}", _peerAddress);
+            _peerAddress = null;
+        }
+    }
+
+    private void TryTrackPeer(Member member)
+    {
+        // Must have our site role, and must not be self
+        if (member.HasRole(_siteRole) && !member.Address.Equals(_cluster.SelfAddress))
+        {
+            _peerAddress = member.Address;
+            _logger.LogInformation("Peer node tracked: {Address}", _peerAddress);
+        }
+    }
+
+    private void SendToPeer(object message)
+    {
+        if (_peerAddress == null)
+        {
+            _logger.LogDebug("No peer available, dropping replication message {Type}", message.GetType().Name);
+            return;
+        }
+
+        var path = new RootActorPath(_peerAddress) / "user" / "site-replication";
+        Context.ActorSelection(path).Tell(message);
+    }
+
+    // ── Inbound handlers ──
+
+    private void HandleApplyConfigDeploy(ApplyConfigDeploy msg)
+    {
+        _logger.LogInformation("Applying replicated config deploy for {Instance}", msg.InstanceName);
+        _storage.StoreDeployedConfigAsync(
+            msg.InstanceName, msg.ConfigJson, msg.DeploymentId, msg.RevisionHash, msg.IsEnabled)
+            .ContinueWith(t =>
+            {
+                if (t.IsFaulted)
+                    _logger.LogError(t.Exception, "Failed to apply replicated deploy for {Instance}", msg.InstanceName);
+            });
+    }
+
+    private void HandleApplyConfigRemove(ApplyConfigRemove msg)
+    {
+        _logger.LogInformation("Applying replicated config remove for {Instance}", msg.InstanceName);
+        _storage.RemoveDeployedConfigAsync(msg.InstanceName)
+            .ContinueWith(t =>
+            {
+                if (t.IsFaulted)
+                    _logger.LogError(t.Exception, "Failed to apply replicated remove for {Instance}", msg.InstanceName);
+            });
+    }
+
+    private void HandleApplyConfigSetEnabled(ApplyConfigSetEnabled msg)
+    {
+        _logger.LogInformation("Applying replicated set-enabled={Enabled} for {Instance}", msg.IsEnabled, msg.InstanceName);
+        _storage.SetInstanceEnabledAsync(msg.InstanceName, msg.IsEnabled)
+            .ContinueWith(t =>
+            {
+                if (t.IsFaulted)
+                    _logger.LogError(t.Exception, "Failed to apply replicated set-enabled for {Instance}", msg.InstanceName);
+            });
+    }
+
+    private void HandleApplyArtifacts(ApplyArtifacts msg)
+    {
+        var command = msg.Command;
+        _logger.LogInformation("Applying replicated artifacts, deploymentId={DeploymentId}", command.DeploymentId);
+
+        Task.Run(async () =>
+        {
+            try
+            {
+                if (command.SharedScripts != null)
+                    foreach (var s in command.SharedScripts)
+                        await _storage.StoreSharedScriptAsync(s.Name, s.Code, s.ParameterDefinitions, s.ReturnDefinition);
+
+                if (command.ExternalSystems != null)
+                    foreach (var es in command.ExternalSystems)
+                        await _storage.StoreExternalSystemAsync(es.Name, es.EndpointUrl, es.AuthType, es.AuthConfiguration, es.MethodDefinitionsJson);
+
+                if (command.DatabaseConnections != null)
+                    foreach (var db in command.DatabaseConnections)
+                        await _storage.StoreDatabaseConnectionAsync(db.Name, db.ConnectionString, db.MaxRetries, db.RetryDelay);
+
+                if (command.NotificationLists != null)
+                    foreach (var nl in command.NotificationLists)
+                        await _storage.StoreNotificationListAsync(nl.Name, nl.RecipientEmails);
+
+                if (command.DataConnections != null)
+                    foreach (var dc in command.DataConnections)
+                        await _storage.StoreDataConnectionDefinitionAsync(dc.Name, dc.Protocol, dc.ConfigurationJson);
+
+                if (command.SmtpConfigurations != null)
+                    foreach (var smtp in command.SmtpConfigurations)
+                        await _storage.StoreSmtpConfigurationAsync(smtp.Name, smtp.Server, smtp.Port, smtp.AuthMode,
+                            smtp.FromAddress, smtp.Username, smtp.Password, smtp.OAuthConfig);
+            }
+            catch (Exception ex)
+            {
+                _logger.LogError(ex, "Failed to apply replicated artifacts");
+            }
+        });
+    }
+
+    private void HandleApplyStoreAndForward(ApplyStoreAndForward msg)
+    {
+        _logger.LogDebug("Applying replicated S&F operation {OpType} for message {Id}",
+            msg.Operation.OperationType, msg.Operation.MessageId);
+
+        _replicationService.ApplyReplicatedOperationAsync(msg.Operation, _sfStorage)
+            .ContinueWith(t =>
+            {
+                if (t.IsFaulted)
+                    _logger.LogError(t.Exception, "Failed to apply replicated S&F operation {Id}", msg.Operation.MessageId);
+            });
+    }
+}

src/ScadaLink.SiteRuntime/Messages/ReplicationMessages.cs

@@ -0,0 +1,34 @@
+using ScadaLink.Commons.Messages.Artifacts;
+using ScadaLink.StoreAndForward;
+
+namespace ScadaLink.SiteRuntime.Messages;
+
+/// <summary>
+/// Outbound messages — sent by local DeploymentManagerActor/S&amp;F service
+/// to the local SiteReplicationActor for forwarding to the peer node.
+/// </summary>
+public record ReplicateConfigDeploy(
+    string InstanceName, string ConfigJson, string DeploymentId, string RevisionHash, bool IsEnabled);
+
+public record ReplicateConfigRemove(string InstanceName);
+
+public record ReplicateConfigSetEnabled(string InstanceName, bool IsEnabled);
+
+public record ReplicateArtifacts(DeployArtifactsCommand Command);
+
+public record ReplicateStoreAndForward(ReplicationOperation Operation);
+
+/// <summary>
+/// Inbound messages — received from the peer's SiteReplicationActor
+/// and applied to local SQLite storage.
+/// </summary>
+public record ApplyConfigDeploy(
+    string InstanceName, string ConfigJson, string DeploymentId, string RevisionHash, bool IsEnabled);
+
+public record ApplyConfigRemove(string InstanceName);
+
+public record ApplyConfigSetEnabled(string InstanceName, bool IsEnabled);
+
+public record ApplyArtifacts(DeployArtifactsCommand Command);
+
+public record ApplyStoreAndForward(ReplicationOperation Operation);

src/ScadaLink.SiteRuntime/ScadaLink.SiteRuntime.csproj

@@ -23,6 +23,7 @@
   <ItemGroup>
     <ProjectReference Include="../ScadaLink.Commons/ScadaLink.Commons.csproj" />
     <ProjectReference Include="../ScadaLink.HealthMonitoring/ScadaLink.HealthMonitoring.csproj" />
+    <ProjectReference Include="../ScadaLink.StoreAndForward/ScadaLink.StoreAndForward.csproj" />
   </ItemGroup>
 
 </Project>

src/ScadaLink.SiteRuntime/Scripts/ScriptCompilationService.cs

@@ -108,7 +108,9 @@ public class ScriptCompilationService
                 .WithReferences(
                     typeof(object).Assembly,
                     typeof(Enumerable).Assembly,
-                    typeof(Math).Assembly)
+                    typeof(Math).Assembly,
+                    typeof(Microsoft.CSharp.RuntimeBinder.CSharpArgumentInfo).Assembly,
+                    typeof(Commons.Types.DynamicJsonElement).Assembly)
                 .WithImports(
                     "System",
                     "System.Collections.Generic",

src/ScadaLink.TemplateEngine/Validation/SemanticValidator.cs

@@ -104,6 +104,20 @@ public class SemanticValidator
             }
         }
 
+        // Validate Call-type scripts have parameter definitions
+        foreach (var script in configuration.Scripts)
+        {
+            if (string.Equals(script.TriggerType, "Call", StringComparison.OrdinalIgnoreCase))
+            {
+                if (string.IsNullOrWhiteSpace(script.ParameterDefinitions))
+                {
+                    warnings.Add(ValidationEntry.Warning(ValidationCategory.MissingMetadata,
+                        $"Call-type script '{script.CanonicalName}' has no parameter definitions.",
+                        script.CanonicalName));
+                }
+            }
+        }
+
         // Validate alarm trigger operand types
         foreach (var alarm in configuration.Alarms)
         {

tests/ScadaLink.ConfigurationDatabase.Tests/ConcurrencyTests.cs

@@ -22,12 +22,15 @@ public class ConcurrencyTestDbContext : ScadaLinkDbContext
     {
         base.OnModelCreating(modelBuilder);
 
-        // Replace the SQL Server RowVersion with an explicit concurrency token for SQLite
-        // Remove the shadow RowVersion property and add a visible ConcurrencyStamp
+        // Replace the SQL Server RowVersion with an explicit concurrency token for SQLite.
+        // SQLite can't auto-generate rowversion, so disable it and use Status as the token instead.
         modelBuilder.Entity<DeploymentRecord>(builder =>
         {
-            // The shadow RowVersion property from the base config doesn't work in SQLite.
-            // Instead, use Status as a concurrency token for the test.
+            builder.Property(d => d.RowVersion)
+                .IsRequired(false)
+                .IsConcurrencyToken(false)
+                .ValueGeneratedNever();
+
             builder.Property(d => d.Status).IsConcurrencyToken();
         });
     }

tests/ScadaLink.ConfigurationDatabase.Tests/RepositoryTests.cs

@@ -68,8 +68,9 @@ public class SecurityRepositoryTests : IDisposable
         await _repository.SaveChangesAsync();
 
         var designMappings = await _repository.GetMappingsByRoleAsync("Design");
-        Assert.Single(designMappings);
-        Assert.Equal("Designers", designMappings[0].LdapGroupName);
+        // Seed data includes "SCADA-Designers" with role "Design", plus the one we added
+        Assert.Equal(2, designMappings.Count);
+        Assert.Contains(designMappings, m => m.LdapGroupName == "Designers");
     }
 
     [Fact]

tests/ScadaLink.ConfigurationDatabase.Tests/SqliteTestHelper.cs

@@ -1,13 +1,15 @@
 using Microsoft.EntityFrameworkCore;
 using Microsoft.EntityFrameworkCore.Diagnostics;
 using Microsoft.EntityFrameworkCore.Storage.ValueConversion;
+using ScadaLink.Commons.Entities.Deployment;
 using ScadaLink.ConfigurationDatabase;
 
 namespace ScadaLink.ConfigurationDatabase.Tests;
 
 /// <summary>
-/// Test DbContext that maps DateTimeOffset to a sortable string format for SQLite.
-/// EF Core 10 SQLite provider does not support ORDER BY on DateTimeOffset columns.
+/// Test DbContext that adapts SQL Server-specific features for SQLite:
+/// - Maps DateTimeOffset to sortable ISO 8601 strings (SQLite has no native DateTimeOffset ORDER BY)
+/// - Replaces SQL Server RowVersion with a nullable byte[] column (SQLite can't auto-generate rowversion)
 /// </summary>
 public class SqliteTestDbContext : ScadaLinkDbContext
 {
@@ -19,6 +21,16 @@ public class SqliteTestDbContext : ScadaLinkDbContext
     {
         base.OnModelCreating(modelBuilder);
 
+        // SQLite cannot auto-generate SQL Server rowversion values.
+        // Replace with a nullable byte[] column so inserts don't fail with NOT NULL constraint.
+        modelBuilder.Entity<DeploymentRecord>(builder =>
+        {
+            builder.Property(d => d.RowVersion)
+                .IsRequired(false)
+                .IsConcurrencyToken(false)
+                .ValueGeneratedNever();
+        });
+
         // Convert DateTimeOffset to ISO 8601 string for SQLite so ORDER BY works
         var converter = new ValueConverter<DateTimeOffset, string>(
             v => v.UtcDateTime.ToString("o"),

tests/ScadaLink.ConfigurationDatabase.Tests/UnitTest1.cs

@@ -21,13 +21,7 @@ public class DbContextTests : IDisposable
 
     public DbContextTests()
     {
-        var options = new DbContextOptionsBuilder<ScadaLinkDbContext>()
-            .UseSqlite("DataSource=:memory:")
-            .Options;
-
-        _context = new ScadaLinkDbContext(options);
-        _context.Database.OpenConnection();
-        _context.Database.EnsureCreated();
+        _context = SqliteTestHelper.CreateInMemoryContext();
     }
 
     public void Dispose()
@@ -429,6 +423,6 @@ public class MigrationHelperTests : IDisposable
     {
         // Verify the InitialCreate migration is detected as pending
         var pending = _context.Database.GetPendingMigrations().ToList();
-        Assert.Contains(pending, m => m.Contains("InitialCreate"));
+        Assert.Contains(pending, m => m.Contains("InitialSchema"));
     }
 }