feat: wire ExternalSystem, Database, and Notify APIs into script runtime

IServiceProvider now flows through the actor chain (DeploymentManagerActor
→ InstanceActor → ScriptActor → ScriptExecutionActor) so scripts can
resolve IExternalSystemClient, IDatabaseGateway, and
INotificationDeliveryService from DI. ScriptGlobals exposes ExternalSystem,
Database, Notify, and Scripts as top-level properties so scripts can use
them without the Instance. prefix.

src/ScadaLink.Host/Actors/AkkaHostedService.cs

@@ -241,7 +241,8 @@ akka {{
                 siteRuntimeOptionsValue,
                 dmLogger,
                 dclManager,
-                siteHealthCollector)),
+                siteHealthCollector,
+                _serviceProvider)),
             terminationMessage: PoisonPill.Instance,
             settings: ClusterSingletonManagerSettings.Create(_actorSystem!)
                 .WithRole(siteRole)

src/ScadaLink.Host/Program.cs

@@ -4,7 +4,6 @@ using ScadaLink.CentralUI;
 using ScadaLink.ClusterInfrastructure;
 using ScadaLink.Communication;
 using ScadaLink.ConfigurationDatabase;
-using ScadaLink.DataConnectionLayer;
 using ScadaLink.DeploymentManager;
 using ScadaLink.ExternalSystemGateway;
 using ScadaLink.HealthMonitoring;
@@ -15,9 +14,6 @@ using ScadaLink.InboundAPI;
 using ScadaLink.ManagementService;
 using ScadaLink.NotificationService;
 using ScadaLink.Security;
-using ScadaLink.SiteEventLogging;
-using ScadaLink.SiteRuntime;
-using ScadaLink.StoreAndForward;
 using ScadaLink.TemplateEngine;
 using Serilog;
 
@@ -98,7 +94,7 @@ try
         builder.Services.AddHostedService(sp => sp.GetRequiredService<AkkaHostedService>());
 
         // Options binding
-        BindSharedOptions(builder.Services, builder.Configuration);
+        SiteServiceRegistration.BindSharedOptions(builder.Services, builder.Configuration);
         builder.Services.Configure<SecurityOptions>(builder.Configuration.GetSection("ScadaLink:Security"));
         builder.Services.Configure<InboundApiOptions>(builder.Configuration.GetSection("ScadaLink:InboundApi"));
 
@@ -148,35 +144,7 @@ try
 
         builder.ConfigureServices((context, services) =>
         {
-            // Shared components
+            SiteServiceRegistration.Configure(services, context.Configuration);
-            services.AddClusterInfrastructure();
-            services.AddCommunication();
-            services.AddSiteHealthMonitoring();
-            services.AddExternalSystemGateway();
-            services.AddNotificationService();
-
-            // Health report transport: sends SiteHealthReport to SiteCommunicationActor via Akka
-            services.AddSingleton<ISiteIdentityProvider, SiteIdentityProvider>();
-            services.AddSingleton<IHealthReportTransport, AkkaHealthReportTransport>();
-
-            // Site-only components — AddSiteRuntime registers SiteStorageService with SQLite path
-            // and site-local repository implementations (IExternalSystemRepository, INotificationRepository)
-            var siteDbPath = context.Configuration["ScadaLink:Database:SiteDbPath"] ?? "site.db";
-            services.AddSiteRuntime($"Data Source={siteDbPath}");
-            services.AddDataConnectionLayer();
-            services.AddStoreAndForward();
-            services.AddSiteEventLogging();
-
-            // WP-13: Akka.NET bootstrap via hosted service
-            services.AddSingleton<AkkaHostedService>();
-            services.AddHostedService(sp => sp.GetRequiredService<AkkaHostedService>());
-
-            // Options binding
-            BindSharedOptions(services, context.Configuration);
-            services.Configure<SiteRuntimeOptions>(context.Configuration.GetSection("ScadaLink:SiteRuntime"));
-            services.Configure<DataConnectionOptions>(context.Configuration.GetSection("ScadaLink:DataConnection"));
-            services.Configure<StoreAndForwardOptions>(context.Configuration.GetSection("ScadaLink:StoreAndForward"));
-            services.Configure<SiteEventLogOptions>(context.Configuration.GetSection("ScadaLink:SiteEventLog"));
         });
 
         var host = builder.Build();
@@ -197,17 +165,6 @@ finally
     await Log.CloseAndFlushAsync();
 }
 
-static void BindSharedOptions(IServiceCollection services, IConfiguration config)
-{
-    services.Configure<NodeOptions>(config.GetSection("ScadaLink:Node"));
-    services.Configure<ClusterOptions>(config.GetSection("ScadaLink:Cluster"));
-    services.Configure<DatabaseOptions>(config.GetSection("ScadaLink:Database"));
-    services.Configure<CommunicationOptions>(config.GetSection("ScadaLink:Communication"));
-    services.Configure<HealthMonitoringOptions>(config.GetSection("ScadaLink:HealthMonitoring"));
-    services.Configure<NotificationOptions>(config.GetSection("ScadaLink:Notification"));
-    services.Configure<LoggingOptions>(config.GetSection("ScadaLink:Logging"));
-}
-
 /// <summary>
 /// Exposes the auto-generated Program class for test infrastructure (e.g. WebApplicationFactory).
 /// </summary>

src/ScadaLink.Host/SiteServiceRegistration.cs

@@ -0,0 +1,63 @@
+using ScadaLink.ClusterInfrastructure;
+using ScadaLink.Communication;
+using ScadaLink.DataConnectionLayer;
+using ScadaLink.ExternalSystemGateway;
+using ScadaLink.HealthMonitoring;
+using ScadaLink.Host.Actors;
+using ScadaLink.NotificationService;
+using ScadaLink.SiteEventLogging;
+using ScadaLink.SiteRuntime;
+using ScadaLink.StoreAndForward;
+
+namespace ScadaLink.Host;
+
+/// <summary>
+/// Extracted site-role DI registrations so both Program.cs and tests
+/// use the same composition root.
+/// </summary>
+public static class SiteServiceRegistration
+{
+    public static void Configure(IServiceCollection services, IConfiguration config)
+    {
+        // Shared components
+        services.AddClusterInfrastructure();
+        services.AddCommunication();
+        services.AddSiteHealthMonitoring();
+        services.AddExternalSystemGateway();
+        services.AddNotificationService();
+
+        // Health report transport: sends SiteHealthReport to SiteCommunicationActor via Akka
+        services.AddSingleton<ISiteIdentityProvider, SiteIdentityProvider>();
+        services.AddSingleton<IHealthReportTransport, AkkaHealthReportTransport>();
+
+        // Site-only components — AddSiteRuntime registers SiteStorageService with SQLite path
+        // and site-local repository implementations (IExternalSystemRepository, INotificationRepository)
+        var siteDbPath = config["ScadaLink:Database:SiteDbPath"] ?? "site.db";
+        services.AddSiteRuntime($"Data Source={siteDbPath}");
+        services.AddDataConnectionLayer();
+        services.AddStoreAndForward();
+        services.AddSiteEventLogging();
+
+        // WP-13: Akka.NET bootstrap via hosted service
+        services.AddSingleton<AkkaHostedService>();
+        services.AddHostedService(sp => sp.GetRequiredService<AkkaHostedService>());
+
+        // Options binding
+        BindSharedOptions(services, config);
+        services.Configure<SiteRuntimeOptions>(config.GetSection("ScadaLink:SiteRuntime"));
+        services.Configure<DataConnectionOptions>(config.GetSection("ScadaLink:DataConnection"));
+        services.Configure<StoreAndForwardOptions>(config.GetSection("ScadaLink:StoreAndForward"));
+        services.Configure<SiteEventLogOptions>(config.GetSection("ScadaLink:SiteEventLog"));
+    }
+
+    public static void BindSharedOptions(IServiceCollection services, IConfiguration config)
+    {
+        services.Configure<NodeOptions>(config.GetSection("ScadaLink:Node"));
+        services.Configure<ClusterOptions>(config.GetSection("ScadaLink:Cluster"));
+        services.Configure<DatabaseOptions>(config.GetSection("ScadaLink:Database"));
+        services.Configure<CommunicationOptions>(config.GetSection("ScadaLink:Communication"));
+        services.Configure<HealthMonitoringOptions>(config.GetSection("ScadaLink:HealthMonitoring"));
+        services.Configure<NotificationOptions>(config.GetSection("ScadaLink:Notification"));
+        services.Configure<LoggingOptions>(config.GetSection("ScadaLink:Logging"));
+    }
+}

src/ScadaLink.SiteRuntime/Actors/DeploymentManagerActor.cs

@@ -32,6 +32,7 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
     private readonly ILogger<DeploymentManagerActor> _logger;
     private readonly IActorRef? _dclManager;
     private readonly ISiteHealthCollector? _healthCollector;
+    private readonly IServiceProvider? _serviceProvider;
     private readonly Dictionary<string, IActorRef> _instanceActors = new();
     private int _totalDeployedCount;
 
@@ -45,7 +46,8 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
         SiteRuntimeOptions options,
         ILogger<DeploymentManagerActor> logger,
         IActorRef? dclManager = null,
-        ISiteHealthCollector? healthCollector = null)
+        ISiteHealthCollector? healthCollector = null,
+        IServiceProvider? serviceProvider = null)
     {
         _storage = storage;
         _compilationService = compilationService;
@@ -54,6 +56,7 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
         _options = options;
         _dclManager = dclManager;
         _healthCollector = healthCollector;
+        _serviceProvider = serviceProvider;
         _logger = logger;
 
         // Lifecycle commands
@@ -561,7 +564,8 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
             _options,
             loggerFactory.CreateLogger<InstanceActor>(),
             _dclManager,
-            _healthCollector));
+            _healthCollector,
+            _serviceProvider));
 
         var actorRef = Context.ActorOf(props, instanceName);
         _instanceActors[instanceName] = actorRef;

src/ScadaLink.SiteRuntime/Actors/InstanceActor.cs

@@ -39,6 +39,7 @@ public class InstanceActor : ReceiveActor
     private readonly SiteRuntimeOptions _options;
     private readonly ILogger _logger;
     private readonly ISiteHealthCollector? _healthCollector;
+    private readonly IServiceProvider? _serviceProvider;
     private readonly Dictionary<string, object?> _attributes = new();
     private readonly Dictionary<string, string> _attributeQualities = new();
     private readonly Dictionary<string, AlarmState> _alarmStates = new();
@@ -64,7 +65,8 @@ public class InstanceActor : ReceiveActor
         SiteRuntimeOptions options,
         ILogger logger,
         IActorRef? dclManager = null,
-        ISiteHealthCollector? healthCollector = null)
+        ISiteHealthCollector? healthCollector = null,
+        IServiceProvider? serviceProvider = null)
     {
         _instanceUniqueName = instanceUniqueName;
         _storage = storage;
@@ -75,6 +77,7 @@ public class InstanceActor : ReceiveActor
         _logger = logger;
         _dclManager = dclManager;
         _healthCollector = healthCollector;
+        _serviceProvider = serviceProvider;
 
         // Deserialize the flattened configuration
         _configuration = JsonSerializer.Deserialize<FlattenedConfiguration>(configJson);
@@ -479,7 +482,8 @@ public class InstanceActor : ReceiveActor
                 _sharedScriptLibrary,
                 _options,
                 _logger,
-                _healthCollector));
+                _healthCollector,
+                _serviceProvider));
 
             var actorRef = Context.ActorOf(props, $"script-{script.CanonicalName}");
             _scriptActors[script.CanonicalName] = actorRef;

src/ScadaLink.SiteRuntime/Actors/ScriptActor.cs

@@ -31,6 +31,7 @@ public class ScriptActor : ReceiveActor, IWithTimers
     private readonly SiteRuntimeOptions _options;
     private readonly ILogger _logger;
     private readonly ISiteHealthCollector? _healthCollector;
+    private readonly IServiceProvider? _serviceProvider;
 
     private Script<object?>? _compiledScript;
     private ScriptTriggerConfig? _triggerConfig;
@@ -49,7 +50,8 @@ public class ScriptActor : ReceiveActor, IWithTimers
         SharedScriptLibrary sharedScriptLibrary,
         SiteRuntimeOptions options,
         ILogger logger,
-        ISiteHealthCollector? healthCollector = null)
+        ISiteHealthCollector? healthCollector = null,
+        IServiceProvider? serviceProvider = null)
     {
         _scriptName = scriptName;
         _instanceName = instanceName;
@@ -59,6 +61,7 @@ public class ScriptActor : ReceiveActor, IWithTimers
         _options = options;
         _logger = logger;
         _healthCollector = healthCollector;
+        _serviceProvider = serviceProvider;
         _minTimeBetweenRuns = scriptConfig.MinTimeBetweenRuns;
 
         // Parse trigger configuration
@@ -212,7 +215,8 @@ public class ScriptActor : ReceiveActor, IWithTimers
             replyTo,
             correlationId,
             _logger,
-            _healthCollector));
+            _healthCollector,
+            _serviceProvider));
 
         Context.ActorOf(props, executionId);
     }

src/ScadaLink.SiteRuntime/Actors/ScriptExecutionActor.cs

@@ -1,6 +1,8 @@
 using Akka.Actor;
 using Microsoft.CodeAnalysis.Scripting;
+using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
+using ScadaLink.Commons.Interfaces.Services;
 using ScadaLink.Commons.Messages.ScriptExecution;
 using ScadaLink.HealthMonitoring;
 using ScadaLink.SiteRuntime.Scripts;
@@ -30,7 +32,8 @@ public class ScriptExecutionActor : ReceiveActor
         IActorRef replyTo,
         string correlationId,
         ILogger logger,
-        ISiteHealthCollector? healthCollector = null)
+        ISiteHealthCollector? healthCollector = null,
+        IServiceProvider? serviceProvider = null)
     {
         // Immediately begin execution
         var self = Self;
@@ -39,7 +42,7 @@ public class ScriptExecutionActor : ReceiveActor
         ExecuteScript(
             scriptName, instanceName, compiledScript, parameters, callDepth,
             instanceActor, sharedScriptLibrary, options, replyTo, correlationId,
-            self, parent, logger, healthCollector);
+            self, parent, logger, healthCollector, serviceProvider);
     }
 
     private static void ExecuteScript(
@@ -56,16 +59,31 @@ public class ScriptExecutionActor : ReceiveActor
         IActorRef self,
         IActorRef parent,
         ILogger logger,
-        ISiteHealthCollector? healthCollector)
+        ISiteHealthCollector? healthCollector,
+        IServiceProvider? serviceProvider)
     {
         var timeout = TimeSpan.FromSeconds(options.ScriptExecutionTimeoutSeconds);
 
         // CTS must be created inside the async lambda so it outlives this method
         _ = Task.Run(async () =>
         {
+            IServiceScope? serviceScope = null;
             using var cts = new CancellationTokenSource(timeout);
             try
             {
+                // Resolve integration services from DI (scoped lifetime)
+                IExternalSystemClient? externalSystemClient = null;
+                IDatabaseGateway? databaseGateway = null;
+                INotificationDeliveryService? notificationService = null;
+
+                if (serviceProvider != null)
+                {
+                    serviceScope = serviceProvider.CreateScope();
+                    externalSystemClient = serviceScope.ServiceProvider.GetService<IExternalSystemClient>();
+                    databaseGateway = serviceScope.ServiceProvider.GetService<IDatabaseGateway>();
+                    notificationService = serviceScope.ServiceProvider.GetService<INotificationDeliveryService>();
+                }
+
                 var context = new ScriptRuntimeContext(
                     instanceActor,
                     self,
@@ -74,7 +92,10 @@ public class ScriptExecutionActor : ReceiveActor
                     options.MaxScriptCallDepth,
                     timeout,
                     instanceName,
-                    logger);
+                    logger,
+                    externalSystemClient,
+                    databaseGateway,
+                    notificationService);
 
                 var globals = new ScriptGlobals
                 {
@@ -123,6 +144,8 @@ public class ScriptExecutionActor : ReceiveActor
             }
             finally
             {
+                // Dispose the DI scope (and scoped services) after script execution completes
+                serviceScope?.Dispose();
                 // Stop self after execution completes
                 self.Tell(PoisonPill.Instance);
             }

src/ScadaLink.SiteRuntime/Scripts/ScriptCompilationService.cs

@@ -178,4 +178,28 @@ public class ScriptGlobals
     public IReadOnlyDictionary<string, object?> Parameters { get; set; } =
         new Dictionary<string, object?>();
     public CancellationToken CancellationToken { get; set; }
+
+    /// <summary>
+    /// Top-level ExternalSystem access for scripts (delegates to Instance.ExternalSystem).
+    /// Usage: ExternalSystem.Call("systemName", "methodName", params)
+    /// </summary>
+    public ScriptRuntimeContext.ExternalSystemHelper ExternalSystem => Instance.ExternalSystem;
+
+    /// <summary>
+    /// Top-level Database access for scripts (delegates to Instance.Database).
+    /// Usage: Database.Connection("name") or Database.CachedWrite("name", "sql", params)
+    /// </summary>
+    public ScriptRuntimeContext.DatabaseHelper Database => Instance.Database;
+
+    /// <summary>
+    /// Top-level Notify access for scripts (delegates to Instance.Notify).
+    /// Usage: Notify.To("listName").Send("subject", "message")
+    /// </summary>
+    public ScriptRuntimeContext.NotifyHelper Notify => Instance.Notify;
+
+    /// <summary>
+    /// Top-level Scripts access for shared script calls (delegates to Instance.Scripts).
+    /// Usage: Scripts.CallShared("scriptName", params)
+    /// </summary>
+    public ScriptRuntimeContext.ScriptCallHelper Scripts => Instance.Scripts;
 }

tests/ScadaLink.Host.Tests/ActorPathTests.cs

@@ -0,0 +1,197 @@
+using Akka.Actor;
+using Microsoft.AspNetCore.Mvc.Testing;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using ScadaLink.ConfigurationDatabase;
+using ScadaLink.Host;
+using ScadaLink.Host.Actors;
+
+namespace ScadaLink.Host.Tests;
+
+[CollectionDefinition("ActorSystem")]
+public class ActorSystemCollection : ICollectionFixture<object> { }
+
+/// <summary>
+/// Verifies that all expected Central-role actors are created at the correct paths
+/// when AkkaHostedService starts.
+/// </summary>
+[Collection("ActorSystem")]
+public class CentralActorPathTests : IAsyncLifetime
+{
+    private WebApplicationFactory<Program>? _factory;
+    private ActorSystem? _actorSystem;
+    private string? _previousEnv;
+
+    public Task InitializeAsync()
+    {
+        _previousEnv = Environment.GetEnvironmentVariable("DOTNET_ENVIRONMENT");
+        Environment.SetEnvironmentVariable("DOTNET_ENVIRONMENT", "Central");
+
+        _factory = new WebApplicationFactory<Program>()
+            .WithWebHostBuilder(builder =>
+            {
+                builder.ConfigureAppConfiguration((_, config) =>
+                {
+                    config.AddInMemoryCollection(new Dictionary<string, string?>
+                    {
+                        ["ScadaLink:Node:NodeHostname"] = "localhost",
+                        ["ScadaLink:Node:RemotingPort"] = "0",
+                        ["ScadaLink:Cluster:SeedNodes:0"] = "akka.tcp://scadalink@localhost:25510",
+                        ["ScadaLink:Cluster:SeedNodes:1"] = "akka.tcp://scadalink@localhost:25520",
+                        ["ScadaLink:Cluster:MinNrOfMembers"] = "1",
+                        ["ScadaLink:Database:SkipMigrations"] = "true",
+                        ["ScadaLink:Security:JwtSigningKey"] = "test-signing-key-must-be-at-least-32-chars-long!",
+                        ["ScadaLink:Security:LdapServer"] = "localhost",
+                        ["ScadaLink:Security:LdapPort"] = "3893",
+                        ["ScadaLink:Security:LdapUseTls"] = "false",
+                        ["ScadaLink:Security:AllowInsecureLdap"] = "true",
+                        ["ScadaLink:Security:LdapSearchBase"] = "dc=scadalink,dc=local",
+                    });
+                });
+                builder.UseSetting("ScadaLink:Node:Role", "Central");
+                builder.UseSetting("ScadaLink:Database:SkipMigrations", "true");
+                builder.ConfigureServices(services =>
+                {
+                    // Replace SQL Server with in-memory database
+                    var descriptorsToRemove = services
+                        .Where(d =>
+                            d.ServiceType == typeof(DbContextOptions<ScadaLinkDbContext>) ||
+                            d.ServiceType == typeof(DbContextOptions) ||
+                            d.ServiceType == typeof(ScadaLinkDbContext) ||
+                            d.ServiceType.FullName?.Contains("EntityFrameworkCore") == true)
+                        .ToList();
+                    foreach (var d in descriptorsToRemove)
+                        services.Remove(d);
+
+                    services.AddDbContext<ScadaLinkDbContext>(options =>
+                        options.UseInMemoryDatabase($"ActorPathTests_{Guid.NewGuid()}"));
+                });
+            });
+
+        // CreateClient triggers host startup including AkkaHostedService
+        _ = _factory.CreateClient();
+
+        var akkaService = _factory.Services.GetRequiredService<AkkaHostedService>();
+        _actorSystem = akkaService.ActorSystem;
+        return Task.CompletedTask;
+    }
+
+    public async Task DisposeAsync()
+    {
+        _factory?.Dispose();
+        Environment.SetEnvironmentVariable("DOTNET_ENVIRONMENT", _previousEnv);
+        await Task.CompletedTask;
+    }
+
+    [Fact]
+    public async Task CentralActors_DeadLetterMonitor_Exists()
+        => await AssertActorExists("/user/dead-letter-monitor");
+
+    [Fact]
+    public async Task CentralActors_CentralCommunication_Exists()
+        => await AssertActorExists("/user/central-communication");
+
+    [Fact]
+    public async Task CentralActors_Management_Exists()
+        => await AssertActorExists("/user/management");
+
+    private async Task AssertActorExists(string path)
+    {
+        Assert.NotNull(_actorSystem);
+        var selection = _actorSystem!.ActorSelection(path);
+        var identity = await selection.Ask<ActorIdentity>(
+            new Identify(path), TimeSpan.FromSeconds(5));
+        Assert.NotNull(identity.Subject);
+    }
+}
+
+/// <summary>
+/// Verifies that all expected Site-role actors are created at the correct paths
+/// when AkkaHostedService starts.
+/// </summary>
+[Collection("ActorSystem")]
+public class SiteActorPathTests : IAsyncLifetime
+{
+    private IHost? _host;
+    private ActorSystem? _actorSystem;
+    private string _tempDbPath = null!;
+
+    public async Task InitializeAsync()
+    {
+        _tempDbPath = Path.Combine(Path.GetTempPath(), $"scadalink_actor_test_{Guid.NewGuid()}.db");
+
+        var builder = Microsoft.Extensions.Hosting.Host.CreateDefaultBuilder();
+        builder.ConfigureAppConfiguration(config =>
+        {
+            config.Sources.Clear();
+            config.AddInMemoryCollection(new Dictionary<string, string?>
+            {
+                ["ScadaLink:Node:Role"] = "Site",
+                ["ScadaLink:Node:NodeHostname"] = "localhost",
+                ["ScadaLink:Node:SiteId"] = "TestSite",
+                ["ScadaLink:Node:RemotingPort"] = "0",
+                ["ScadaLink:Cluster:SeedNodes:0"] = "akka.tcp://scadalink@localhost:25510",
+                ["ScadaLink:Cluster:SeedNodes:1"] = "akka.tcp://scadalink@localhost:25520",
+                ["ScadaLink:Cluster:MinNrOfMembers"] = "1",
+                ["ScadaLink:Database:SiteDbPath"] = _tempDbPath,
+                // Configure a dummy central contact point to trigger ClusterClient creation
+                ["ScadaLink:Communication:CentralContactPoints:0"] = "akka.tcp://scadalink@localhost:25510",
+            });
+        });
+        builder.ConfigureServices((context, services) =>
+        {
+            SiteServiceRegistration.Configure(services, context.Configuration);
+        });
+
+        _host = builder.Build();
+        await _host.StartAsync();
+
+        var akkaService = _host.Services.GetRequiredService<AkkaHostedService>();
+        _actorSystem = akkaService.ActorSystem;
+    }
+
+    public async Task DisposeAsync()
+    {
+        if (_host != null)
+        {
+            await _host.StopAsync();
+            _host.Dispose();
+        }
+        try { File.Delete(_tempDbPath); } catch { /* best effort */ }
+    }
+
+    [Fact]
+    public async Task SiteActors_DeadLetterMonitor_Exists()
+        => await AssertActorExists("/user/dead-letter-monitor");
+
+    [Fact]
+    public async Task SiteActors_DclManager_Exists()
+        => await AssertActorExists("/user/dcl-manager");
+
+    [Fact]
+    public async Task SiteActors_DeploymentManagerSingleton_Exists()
+        => await AssertActorExists("/user/deployment-manager-singleton");
+
+    [Fact]
+    public async Task SiteActors_DeploymentManagerProxy_Exists()
+        => await AssertActorExists("/user/deployment-manager-proxy");
+
+    [Fact]
+    public async Task SiteActors_SiteCommunication_Exists()
+        => await AssertActorExists("/user/site-communication");
+
+    [Fact]
+    public async Task SiteActors_CentralClusterClient_Exists()
+        => await AssertActorExists("/user/central-cluster-client");
+
+    private async Task AssertActorExists(string path)
+    {
+        Assert.NotNull(_actorSystem);
+        var selection = _actorSystem!.ActorSelection(path);
+        var identity = await selection.Ask<ActorIdentity>(
+            new Identify(path), TimeSpan.FromSeconds(5));
+        Assert.NotNull(identity.Subject);
+    }
+}

tests/ScadaLink.Host.Tests/CompositionRootTests.cs

@@ -0,0 +1,429 @@
+using Microsoft.AspNetCore.Components.Authorization;
+using Microsoft.AspNetCore.Mvc.Testing;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Hosting;
+using Microsoft.Extensions.Options;
+using ScadaLink.ClusterInfrastructure;
+using ScadaLink.Communication;
+using ScadaLink.Commons.Interfaces.Repositories;
+using ScadaLink.Commons.Interfaces.Services;
+using ScadaLink.ConfigurationDatabase;
+using ScadaLink.DataConnectionLayer;
+using ScadaLink.DeploymentManager;
+using ScadaLink.ExternalSystemGateway;
+using ScadaLink.HealthMonitoring;
+using ScadaLink.Host;
+using ScadaLink.Host.Actors;
+using ScadaLink.InboundAPI;
+using ScadaLink.ManagementService;
+using ScadaLink.NotificationService;
+using ScadaLink.Security;
+using ScadaLink.SiteEventLogging;
+using ScadaLink.SiteRuntime;
+using ScadaLink.SiteRuntime.Persistence;
+using ScadaLink.SiteRuntime.Repositories;
+using ScadaLink.SiteRuntime.Scripts;
+using ScadaLink.StoreAndForward;
+using ScadaLink.TemplateEngine;
+using ScadaLink.TemplateEngine.Flattening;
+using ScadaLink.TemplateEngine.Services;
+using ScadaLink.TemplateEngine.Validation;
+
+namespace ScadaLink.Host.Tests;
+
+/// <summary>
+/// Removes AkkaHostedService from running as a hosted service while keeping it
+/// resolvable in DI (other services like AkkaHealthReportTransport depend on it).
+/// </summary>
+internal static class AkkaHostedServiceRemover
+{
+    internal static void RemoveAkkaHostedServiceOnly(IServiceCollection services)
+    {
+        // Pattern used in Program.cs:
+        //   services.AddSingleton<AkkaHostedService>();             // index N
+        //   services.AddHostedService(sp => sp.GetRequiredService<AkkaHostedService>());  // index N+1
+        // We keep the singleton so DI resolution works, but remove the IHostedService
+        // factory so StartAsync is never called.
+        int akkaIndex = -1;
+        for (int i = 0; i < services.Count; i++)
+        {
+            if (services[i].ServiceType == typeof(AkkaHostedService))
+            {
+                akkaIndex = i;
+                break;
+            }
+        }
+
+        if (akkaIndex < 0) return;
+
+        // The IHostedService factory is the next registration after the singleton
+        for (int i = akkaIndex + 1; i < services.Count; i++)
+        {
+            if (services[i].ServiceType == typeof(IHostedService)
+                && services[i].ImplementationFactory != null)
+            {
+                services.RemoveAt(i);
+                break;
+            }
+        }
+    }
+}
+
+/// <summary>
+/// Verifies every expected DI service resolves from the Central composition root.
+/// Uses WebApplicationFactory to exercise the real Program.cs pipeline.
+/// </summary>
+public class CentralCompositionRootTests : IDisposable
+{
+    private readonly WebApplicationFactory<Program> _factory;
+    private readonly string? _previousEnv;
+
+    public CentralCompositionRootTests()
+    {
+        _previousEnv = Environment.GetEnvironmentVariable("DOTNET_ENVIRONMENT");
+        Environment.SetEnvironmentVariable("DOTNET_ENVIRONMENT", "Central");
+
+        _factory = new WebApplicationFactory<Program>()
+            .WithWebHostBuilder(builder =>
+            {
+                builder.ConfigureAppConfiguration((_, config) =>
+                {
+                    config.AddInMemoryCollection(new Dictionary<string, string?>
+                    {
+                        ["ScadaLink:Node:NodeHostname"] = "localhost",
+                        ["ScadaLink:Node:RemotingPort"] = "0",
+                        ["ScadaLink:Cluster:SeedNodes:0"] = "akka.tcp://scadalink@localhost:2551",
+                        ["ScadaLink:Cluster:SeedNodes:1"] = "akka.tcp://scadalink@localhost:2552",
+                        ["ScadaLink:Database:SkipMigrations"] = "true",
+                        ["ScadaLink:Security:JwtSigningKey"] = "test-signing-key-must-be-at-least-32-chars-long!",
+                        ["ScadaLink:Security:LdapServer"] = "localhost",
+                        ["ScadaLink:Security:LdapPort"] = "3893",
+                        ["ScadaLink:Security:LdapUseTls"] = "false",
+                        ["ScadaLink:Security:AllowInsecureLdap"] = "true",
+                        ["ScadaLink:Security:LdapSearchBase"] = "dc=scadalink,dc=local",
+                    });
+                });
+                builder.UseSetting("ScadaLink:Node:Role", "Central");
+                builder.UseSetting("ScadaLink:Database:SkipMigrations", "true");
+                builder.ConfigureServices(services =>
+                {
+                    // Replace SQL Server with in-memory database
+                    var descriptorsToRemove = services
+                        .Where(d =>
+                            d.ServiceType == typeof(DbContextOptions<ScadaLinkDbContext>) ||
+                            d.ServiceType == typeof(DbContextOptions) ||
+                            d.ServiceType == typeof(ScadaLinkDbContext) ||
+                            d.ServiceType.FullName?.Contains("EntityFrameworkCore") == true)
+                        .ToList();
+                    foreach (var d in descriptorsToRemove)
+                        services.Remove(d);
+
+                    services.AddDbContext<ScadaLinkDbContext>(options =>
+                        options.UseInMemoryDatabase($"CompositionRootTests_{Guid.NewGuid()}"));
+
+                    // Keep AkkaHostedService in DI (other services depend on it)
+                    // but prevent it from starting by removing only its IHostedService registration.
+                    AkkaHostedServiceRemover.RemoveAkkaHostedServiceOnly(services);
+                });
+            });
+
+        // Trigger host build
+        _ = _factory.Server;
+    }
+
+    public void Dispose()
+    {
+        _factory.Dispose();
+        Environment.SetEnvironmentVariable("DOTNET_ENVIRONMENT", _previousEnv);
+    }
+
+    // --- Singletons ---
+
+    [Theory]
+    [MemberData(nameof(CentralSingletonServices))]
+    public void Central_ResolveSingleton(Type serviceType)
+    {
+        var service = _factory.Services.GetService(serviceType);
+        Assert.NotNull(service);
+    }
+
+    public static IEnumerable<object[]> CentralSingletonServices => new[]
+    {
+        new object[] { typeof(CommunicationService) },
+        new object[] { typeof(ISiteHealthCollector) },
+        new object[] { typeof(CentralHealthAggregator) },
+        new object[] { typeof(ICentralHealthAggregator) },
+        new object[] { typeof(OperationLockManager) },
+        new object[] { typeof(OAuth2TokenService) },
+        new object[] { typeof(InboundScriptExecutor) },
+    };
+
+    // --- Scoped services ---
+
+    [Theory]
+    [MemberData(nameof(CentralScopedServices))]
+    public void Central_ResolveScoped(Type serviceType)
+    {
+        using var scope = _factory.Services.CreateScope();
+        var service = scope.ServiceProvider.GetService(serviceType);
+        Assert.NotNull(service);
+    }
+
+    public static IEnumerable<object[]> CentralScopedServices => new[]
+    {
+        // TemplateEngine
+        new object[] { typeof(TemplateService) },
+        new object[] { typeof(SharedScriptService) },
+        new object[] { typeof(InstanceService) },
+        new object[] { typeof(SiteService) },
+        new object[] { typeof(AreaService) },
+        new object[] { typeof(TemplateDeletionService) },
+        // DeploymentManager
+        new object[] { typeof(IFlatteningPipeline) },
+        new object[] { typeof(DeploymentService) },
+        new object[] { typeof(ArtifactDeploymentService) },
+        // Security
+        new object[] { typeof(LdapAuthService) },
+        new object[] { typeof(JwtTokenService) },
+        new object[] { typeof(RoleMapper) },
+        // InboundAPI
+        new object[] { typeof(ApiKeyValidator) },
+        new object[] { typeof(RouteHelper) },
+        // ExternalSystemGateway
+        new object[] { typeof(ExternalSystemClient) },
+        new object[] { typeof(IExternalSystemClient) },
+        new object[] { typeof(DatabaseGateway) },
+        new object[] { typeof(IDatabaseGateway) },
+        // NotificationService
+        new object[] { typeof(NotificationDeliveryService) },
+        new object[] { typeof(INotificationDeliveryService) },
+        // ConfigurationDatabase repositories
+        new object[] { typeof(ScadaLinkDbContext) },
+        new object[] { typeof(ISecurityRepository) },
+        new object[] { typeof(ICentralUiRepository) },
+        new object[] { typeof(ITemplateEngineRepository) },
+        new object[] { typeof(IDeploymentManagerRepository) },
+        new object[] { typeof(ISiteRepository) },
+        new object[] { typeof(IExternalSystemRepository) },
+        new object[] { typeof(INotificationRepository) },
+        new object[] { typeof(IInboundApiRepository) },
+        new object[] { typeof(IAuditService) },
+        new object[] { typeof(IInstanceLocator) },
+        // CentralUI
+        new object[] { typeof(AuthenticationStateProvider) },
+    };
+
+    // --- Transient services ---
+
+    [Theory]
+    [MemberData(nameof(CentralTransientServices))]
+    public void Central_ResolveTransient(Type serviceType)
+    {
+        using var scope = _factory.Services.CreateScope();
+        var service = scope.ServiceProvider.GetService(serviceType);
+        Assert.NotNull(service);
+    }
+
+    public static IEnumerable<object[]> CentralTransientServices => new[]
+    {
+        new object[] { typeof(FlatteningService) },
+        new object[] { typeof(DiffService) },
+        new object[] { typeof(RevisionHashService) },
+        new object[] { typeof(ScriptCompiler) },
+        new object[] { typeof(SemanticValidator) },
+        new object[] { typeof(ValidationService) },
+    };
+
+    // --- Options ---
+
+    [Theory]
+    [MemberData(nameof(CentralOptions))]
+    public void Central_ResolveOptions(Type optionsType)
+    {
+        var service = _factory.Services.GetService(optionsType);
+        Assert.NotNull(service);
+    }
+
+    public static IEnumerable<object[]> CentralOptions => new[]
+    {
+        new object[] { typeof(IOptions<NodeOptions>) },
+        new object[] { typeof(IOptions<ClusterOptions>) },
+        new object[] { typeof(IOptions<DatabaseOptions>) },
+        new object[] { typeof(IOptions<CommunicationOptions>) },
+        new object[] { typeof(IOptions<HealthMonitoringOptions>) },
+        new object[] { typeof(IOptions<NotificationOptions>) },
+        new object[] { typeof(IOptions<LoggingOptions>) },
+        new object[] { typeof(IOptions<SecurityOptions>) },
+        new object[] { typeof(IOptions<InboundApiOptions>) },
+        new object[] { typeof(IOptions<ManagementServiceOptions>) },
+        new object[] { typeof(IOptions<ExternalSystemGatewayOptions>) },
+    };
+
+    // --- Hosted services ---
+
+    [Fact]
+    public void Central_CentralHealthAggregator_RegisteredAsHostedService()
+    {
+        var hostedServices = _factory.Services.GetServices<IHostedService>();
+        Assert.Contains(hostedServices, s => s.GetType() == typeof(CentralHealthAggregator));
+    }
+}
+
+/// <summary>
+/// Verifies every expected DI service resolves from the Site composition root.
+/// Uses the extracted SiteServiceRegistration.Configure() so the test always
+/// matches the real Program.cs registration.
+/// </summary>
+public class SiteCompositionRootTests : IDisposable
+{
+    private readonly IHost _host;
+    private readonly string _tempDbPath;
+
+    public SiteCompositionRootTests()
+    {
+        _tempDbPath = Path.Combine(Path.GetTempPath(), $"scadalink_test_{Guid.NewGuid()}.db");
+
+        var builder = Microsoft.Extensions.Hosting.Host.CreateDefaultBuilder();
+        builder.ConfigureAppConfiguration(config =>
+        {
+            config.Sources.Clear();
+            config.AddInMemoryCollection(new Dictionary<string, string?>
+            {
+                ["ScadaLink:Node:Role"] = "Site",
+                ["ScadaLink:Node:NodeHostname"] = "test-site",
+                ["ScadaLink:Node:SiteId"] = "TestSite",
+                ["ScadaLink:Node:RemotingPort"] = "0",
+                ["ScadaLink:Database:SiteDbPath"] = _tempDbPath,
+            });
+        });
+        builder.ConfigureServices((context, services) =>
+        {
+            SiteServiceRegistration.Configure(services, context.Configuration);
+
+            // Keep AkkaHostedService in DI (other services depend on it)
+            // but prevent it from starting by removing only its IHostedService registration.
+            AkkaHostedServiceRemover.RemoveAkkaHostedServiceOnly(services);
+        });
+
+        _host = builder.Build();
+    }
+
+    public void Dispose()
+    {
+        _host.Dispose();
+        try { File.Delete(_tempDbPath); } catch { /* best effort */ }
+    }
+
+    // --- Singletons ---
+
+    [Theory]
+    [MemberData(nameof(SiteSingletonServices))]
+    public void Site_ResolveSingleton(Type serviceType)
+    {
+        var service = _host.Services.GetService(serviceType);
+        Assert.NotNull(service);
+    }
+
+    public static IEnumerable<object[]> SiteSingletonServices => new[]
+    {
+        new object[] { typeof(CommunicationService) },
+        new object[] { typeof(ISiteHealthCollector) },
+        new object[] { typeof(SiteStorageService) },
+        new object[] { typeof(ScriptCompilationService) },
+        new object[] { typeof(SharedScriptLibrary) },
+        new object[] { typeof(IDataConnectionFactory) },
+        new object[] { typeof(StoreAndForwardStorage) },
+        new object[] { typeof(StoreAndForwardService) },
+        new object[] { typeof(ReplicationService) },
+        new object[] { typeof(ISiteEventLogger) },
+        new object[] { typeof(IEventLogQueryService) },
+        new object[] { typeof(OAuth2TokenService) },
+        new object[] { typeof(ISiteIdentityProvider) },
+        new object[] { typeof(IHealthReportTransport) },
+    };
+
+    // --- Scoped services ---
+
+    [Theory]
+    [MemberData(nameof(SiteScopedServices))]
+    public void Site_ResolveScoped(Type serviceType)
+    {
+        using var scope = _host.Services.CreateScope();
+        var service = scope.ServiceProvider.GetService(serviceType);
+        Assert.NotNull(service);
+    }
+
+    public static IEnumerable<object[]> SiteScopedServices => new[]
+    {
+        new object[] { typeof(IExternalSystemRepository) },
+        new object[] { typeof(INotificationRepository) },
+        new object[] { typeof(ExternalSystemClient) },
+        new object[] { typeof(IExternalSystemClient) },
+        new object[] { typeof(DatabaseGateway) },
+        new object[] { typeof(IDatabaseGateway) },
+        new object[] { typeof(NotificationDeliveryService) },
+        new object[] { typeof(INotificationDeliveryService) },
+    };
+
+    // --- Implementation type assertions ---
+
+    [Fact]
+    public void Site_ExternalSystemRepository_IsSiteImplementation()
+    {
+        using var scope = _host.Services.CreateScope();
+        var repo = scope.ServiceProvider.GetRequiredService<IExternalSystemRepository>();
+        Assert.IsType<SiteExternalSystemRepository>(repo);
+    }
+
+    [Fact]
+    public void Site_NotificationRepository_IsSiteImplementation()
+    {
+        using var scope = _host.Services.CreateScope();
+        var repo = scope.ServiceProvider.GetRequiredService<INotificationRepository>();
+        Assert.IsType<SiteNotificationRepository>(repo);
+    }
+
+    // --- Options ---
+
+    [Theory]
+    [MemberData(nameof(SiteOptions))]
+    public void Site_ResolveOptions(Type optionsType)
+    {
+        var service = _host.Services.GetService(optionsType);
+        Assert.NotNull(service);
+    }
+
+    public static IEnumerable<object[]> SiteOptions => new[]
+    {
+        new object[] { typeof(IOptions<NodeOptions>) },
+        new object[] { typeof(IOptions<ClusterOptions>) },
+        new object[] { typeof(IOptions<DatabaseOptions>) },
+        new object[] { typeof(IOptions<CommunicationOptions>) },
+        new object[] { typeof(IOptions<HealthMonitoringOptions>) },
+        new object[] { typeof(IOptions<NotificationOptions>) },
+        new object[] { typeof(IOptions<LoggingOptions>) },
+        new object[] { typeof(IOptions<SiteRuntimeOptions>) },
+        new object[] { typeof(IOptions<DataConnectionOptions>) },
+        new object[] { typeof(IOptions<StoreAndForwardOptions>) },
+        new object[] { typeof(IOptions<SiteEventLogOptions>) },
+    };
+
+    // --- Hosted services ---
+
+    [Theory]
+    [MemberData(nameof(SiteHostedServices))]
+    public void Site_HostedServiceRegistered(Type expectedType)
+    {
+        var hostedServices = _host.Services.GetServices<IHostedService>();
+        Assert.Contains(hostedServices, s => s.GetType() == expectedType);
+    }
+
+    public static IEnumerable<object[]> SiteHostedServices => new[]
+    {
+        new object[] { typeof(HealthReportSender) },
+        new object[] { typeof(SiteStorageInitializer) },
+        new object[] { typeof(EventLogPurgeService) },
+    };
+}

tests/ScadaLink.Host.Tests/HostStartupTests.cs

@@ -3,16 +3,7 @@ using Microsoft.AspNetCore.Mvc.Testing;
 using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Hosting;
-using ScadaLink.ClusterInfrastructure;
-using ScadaLink.Communication;
-using ScadaLink.DataConnectionLayer;
-using ScadaLink.ExternalSystemGateway;
-using ScadaLink.HealthMonitoring;
 using ScadaLink.Host;
-using ScadaLink.NotificationService;
-using ScadaLink.SiteEventLogging;
-using ScadaLink.SiteRuntime;
-using ScadaLink.StoreAndForward;
 
 namespace ScadaLink.Host.Tests;
 
@@ -83,35 +74,12 @@ public class HostStartupTests : IDisposable
                 ["ScadaLink:Node:Role"] = "Site",
                 ["ScadaLink:Node:NodeHostname"] = "test-site",
                 ["ScadaLink:Node:SiteId"] = "TestSite",
-                ["ScadaLink:Node:RemotingPort"] = "8082",
+                ["ScadaLink:Node:RemotingPort"] = "0",
             });
         });
         builder.ConfigureServices((context, services) =>
         {
-            // Shared components
+            SiteServiceRegistration.Configure(services, context.Configuration);
-            services.AddClusterInfrastructure();
-            services.AddCommunication();
-            services.AddHealthMonitoring();
-            services.AddExternalSystemGateway();
-            services.AddNotificationService();
-
-            // Site-only components
-            services.AddSiteRuntime();
-            services.AddDataConnectionLayer();
-            services.AddStoreAndForward();
-            services.AddSiteEventLogging();
-
-            // Options binding (mirrors Program.cs site path)
-            services.Configure<NodeOptions>(context.Configuration.GetSection("ScadaLink:Node"));
-            services.Configure<ClusterOptions>(context.Configuration.GetSection("ScadaLink:Cluster"));
-            services.Configure<DatabaseOptions>(context.Configuration.GetSection("ScadaLink:Database"));
-            services.Configure<CommunicationOptions>(context.Configuration.GetSection("ScadaLink:Communication"));
-            services.Configure<HealthMonitoringOptions>(context.Configuration.GetSection("ScadaLink:HealthMonitoring"));
-            services.Configure<NotificationOptions>(context.Configuration.GetSection("ScadaLink:Notification"));
-            services.Configure<LoggingOptions>(context.Configuration.GetSection("ScadaLink:Logging"));
-            services.Configure<DataConnectionOptions>(context.Configuration.GetSection("ScadaLink:DataConnection"));
-            services.Configure<StoreAndForwardOptions>(context.Configuration.GetSection("ScadaLink:StoreAndForward"));
-            services.Configure<SiteEventLogOptions>(context.Configuration.GetSection("ScadaLink:SiteEventLog"));
         });
 
         var host = builder.Build();
@@ -134,20 +102,12 @@ public class HostStartupTests : IDisposable
                 ["ScadaLink:Node:Role"] = "Site",
                 ["ScadaLink:Node:NodeHostname"] = "test-site",
                 ["ScadaLink:Node:SiteId"] = "TestSite",
-                ["ScadaLink:Node:RemotingPort"] = "8082",
+                ["ScadaLink:Node:RemotingPort"] = "0",
             });
         });
         builder.ConfigureServices((context, services) =>
         {
-            services.AddClusterInfrastructure();
+            SiteServiceRegistration.Configure(services, context.Configuration);
-            services.AddCommunication();
-            services.AddHealthMonitoring();
-            services.AddExternalSystemGateway();
-            services.AddNotificationService();
-            services.AddSiteRuntime();
-            services.AddDataConnectionLayer();
-            services.AddStoreAndForward();
-            services.AddSiteEventLogging();
         });
 
         var host = builder.Build();

tests/ScadaLink.Host.Tests/ScadaLink.Host.Tests.csproj

@@ -16,6 +16,7 @@
     <PackageReference Include="Akka.TestKit.Xunit2" Version="1.5.62" />
     <PackageReference Include="coverlet.collector" Version="6.0.4" />
     <PackageReference Include="Microsoft.AspNetCore.Mvc.Testing" Version="10.0.5" />
+    <PackageReference Include="Microsoft.EntityFrameworkCore.InMemory" Version="10.0.5" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1" />
     <PackageReference Include="Serilog" Version="4.3.1" />
     <PackageReference Include="xunit" Version="2.9.3" />