fix(auditlog): populate the Actor column on outbound and central rows

Per the Audit Log Actor-column spec, Actor should carry the calling script
identity on outbound rows (ApiCall, DbWrite, NotifySend) and a system identity
on central-dispatch rows (NotifyDeliver). The original emission code hard-coded
Actor=null at all four sites, so only Inbound API rows (API key name) ever
filled it. Stamp the script identity and 'system' respectively.

src/ScadaLink.NotificationOutbox/NotificationOutboxActor.cs

@@ -30,6 +30,13 @@ public class NotificationOutboxActor : ReceiveActor, IWithTimers
     private const int FallbackMaxRetries = 10;
     private static readonly TimeSpan FallbackRetryDelay = TimeSpan.FromMinutes(1);
 
+    /// <summary>
+    /// Audit <c>Actor</c> stamped on central-dispatch (<c>NotifyDeliver</c>) rows.
+    /// The Actor-column spec assigns central-originated audit rows a system
+    /// identity — there is no per-call authenticated user at dispatch time.
+    /// </summary>
+    private const string SystemActor = "system";
+
     private readonly IServiceProvider _serviceProvider;
     private readonly NotificationOutboxOptions _options;
     private readonly ICentralAuditWriter _auditWriter;
@@ -500,9 +507,11 @@ public class NotificationOutboxActor : ReceiveActor, IWithTimers
             Channel = AuditChannel.Notification,
             Kind = AuditKind.NotifyDeliver,
             CorrelationId = correlationId,
-            // Central dispatch — no authenticated actor (the originating
-            // script's identity is captured on the upstream NotifySend row).
-            Actor = null,
+            // Central dispatch — a system identity per the Actor-column spec;
+            // there is no per-call authenticated user here. The originating
+            // script is still captured on SourceScript (and on the upstream
+            // NotifySend row).
+            Actor = SystemActor,
             SourceSiteId = notification.SourceSiteId,
             SourceInstanceId = notification.SourceInstanceId,
             SourceScript = notification.SourceScript,

src/ScadaLink.SiteRuntime/Scripts/AuditingDbCommand.cs

@@ -430,7 +430,10 @@ internal sealed class AuditingDbCommand : DbCommand
             SourceSiteId = string.IsNullOrEmpty(_siteId) ? null : _siteId,
             SourceInstanceId = _instanceName,
             SourceScript = _sourceScript,
-            Actor = null,
+            // Outbound channel: per the Audit Log Actor-column spec the actor is
+            // the calling script. Null when no single script owns the call
+            // (e.g. a shared script running inline).
+            Actor = _sourceScript,
             Target = target,
             Status = status,
             HttpStatus = null,

src/ScadaLink.SiteRuntime/Scripts/ScriptRuntimeContext.cs

@@ -875,7 +875,10 @@ public class ScriptRuntimeContext
                 SourceSiteId = string.IsNullOrEmpty(_siteId) ? null : _siteId,
                 SourceInstanceId = _instanceName,
                 SourceScript = _sourceScript,
-                Actor = null,
+                // Outbound channel: per the Audit Log Actor-column spec the actor
+                // is the calling script. Null when no single script owns the call
+                // (e.g. a shared script running inline).
+                Actor = _sourceScript,
                 Target = $"{systemName}.{methodName}",
                 Status = status,
                 HttpStatus = httpStatus,
@@ -1355,7 +1358,10 @@ public class ScriptRuntimeContext
                     SourceSiteId = string.IsNullOrEmpty(_siteId) ? null : _siteId,
                     SourceInstanceId = _instanceName,
                     SourceScript = _sourceScript,
-                    Actor = null,
+                    // Outbound channel: per the Audit Log Actor-column spec the
+                    // actor is the calling script. Null when no single script
+                    // owns the call (e.g. a shared script running inline).
+                    Actor = _sourceScript,
                     Target = _listName,
                     Status = AuditStatus.Submitted,
                     HttpStatus = null,

tests/ScadaLink.NotificationOutbox.Tests/NotificationOutboxActorAttemptEmissionTests.cs

@@ -155,8 +155,8 @@ public class NotificationOutboxActorAttemptEmissionTests : TestKit
             Assert.Equal("site-alpha", evt.SourceSiteId);
             Assert.Equal("instance-42", evt.SourceInstanceId);
             Assert.Equal("AlarmScript", evt.SourceScript);
-            // Central dispatch: actor is null (no authenticated end-user).
-            Assert.Null(evt.Actor);
+            // Central dispatch: Actor is the system identity (no per-call user).
+            Assert.Equal("system", evt.Actor);
             // Successful attempt: no error message.
             Assert.Null(evt.ErrorMessage);
         });

tests/ScadaLink.SiteRuntime.Tests/Scripts/DatabaseSyncEmissionTests.cs

@@ -266,7 +266,8 @@ public class DatabaseSyncEmissionTests
         Assert.Equal(SiteId, evt.SourceSiteId);
         Assert.Equal(InstanceName, evt.SourceInstanceId);
         Assert.Equal(SourceScript, evt.SourceScript);
-        Assert.Null(evt.Actor);
+        // Outbound channel: Actor carries the calling script identity.
+        Assert.Equal(SourceScript, evt.Actor);
         Assert.Null(evt.CorrelationId);
         Assert.NotEqual(Guid.Empty, evt.EventId);
     }

tests/ScadaLink.SiteRuntime.Tests/Scripts/ExternalSystemCallAuditEmissionTests.cs

@@ -186,7 +186,8 @@ public class ExternalSystemCallAuditEmissionTests
         Assert.Equal(SiteId, evt.SourceSiteId);
         Assert.Equal(InstanceName, evt.SourceInstanceId);
         Assert.Equal(SourceScript, evt.SourceScript);
-        Assert.Null(evt.Actor);
+        // Outbound channel: Actor carries the calling script identity.
+        Assert.Equal(SourceScript, evt.Actor);
         Assert.Null(evt.CorrelationId);
     }
 

tests/ScadaLink.SiteRuntime.Tests/Scripts/NotifySendAuditEmissionTests.cs

@@ -127,7 +127,8 @@ public class NotifySendAuditEmissionTests : TestKit, IAsyncLifetime, IDisposable
         Assert.Null(evt.HttpStatus);
         Assert.Null(evt.ErrorMessage);
         Assert.Null(evt.ErrorDetail);
-        Assert.Null(evt.Actor);
+        // Outbound channel: Actor carries the calling script identity.
+        Assert.Equal(SourceScript, evt.Actor);
     }
 
     [Fact]
@@ -199,7 +200,8 @@ public class NotifySendAuditEmissionTests : TestKit, IAsyncLifetime, IDisposable
         Assert.Equal(SiteId, evt.SourceSiteId);
         Assert.Equal(InstanceName, evt.SourceInstanceId);
         Assert.Equal(SourceScript, evt.SourceScript);
-        Assert.Null(evt.Actor);
+        // Outbound channel: Actor carries the calling script identity.
+        Assert.Equal(SourceScript, evt.Actor);
     }
 
     [Fact]