fix(site-runtime): reconcile artifact deletions on apply — central deletes no longer orphan site rows

The artifact apply (DeploymentManagerActor.HandleDeployArtifacts) was
upsert-only, so deleting an external system (or shared script, DB connection,
data connection) centrally never removed the site's SQLite row — a deleted
external system stayed callable from site scripts forever. Central always
ships the COMPLETE set of each artifact class (ArtifactDeploymentService
GetAll* snapshots; the wire's presence-tracking wrapper lists preserve
null-vs-empty), so the site now applies upsert-then-reconcile: after storing
the incoming set, SiteStorageService.DeleteRowsExceptAsync removes any stored
row absent from it, per artifact table. A null list still means 'field not
shipped' and touches nothing.

Runtime cleanup rides along: a reconciled-away shared script is unregistered
from the compiled SharedScriptLibrary (a stale delegate would stay callable
until restart), and a removed data connection is evicted from the DCL hash
cache and its live connection actor stopped via the previously-caller-less
RemoveConnectionCommand — both on the actor thread via the extended
ApplyArtifactDataConnectionsToDcl message. All four tables are
RegisterReplicated, so the deletes reach the standby as ordinary CDC row
tombstones.

Tests: storage-level reconcile per table (incl. empty-set-deletes-all and
idempotency) in ArtifactStorageTests; actor-level pins in
DeploymentManagerActorTests (orphan delete, null-set no-op, library
unregistration, DCL stop for the removed connection only). Docs:
Component-DeploymentManager + Component-SiteRuntime record the
full-set/reconcile semantics.

src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Actors/DeploymentManagerActor.cs

@@ -1870,6 +1870,14 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
         {
             try
             {
+                // Each non-null artifact list is the COMPLETE system-wide set
+                // (ArtifactDeploymentService ships GetAll* snapshots), so the apply is
+                // upsert-then-reconcile: store every incoming artifact, then delete any
+                // stored row absent from the set — that artifact was deleted centrally.
+                // Upsert-only apply used to leave such rows orphaned on the site forever
+                // (a centrally-deleted external system stayed callable from site scripts).
+                // A null list means "field not shipped" and touches nothing.
+
                 // Store shared scripts and recompile
                 if (command.SharedScripts != null)
                 {
@@ -1881,6 +1889,11 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
                         // Shared scripts recompiled on update
                         _sharedScriptLibrary.CompileAndRegister(script.Name, script.Code);
                     }
+
+                    var removedScripts = await _storage.DeleteSharedScriptsExceptAsync(
+                        command.SharedScripts.Select(s => s.Name).ToList());
+                    foreach (var name in removedScripts)
+                        _sharedScriptLibrary.Remove(name);
                 }
 
                 // Store external system definitions
@@ -1891,6 +1904,9 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
                         await _storage.StoreExternalSystemAsync(es.Name, es.EndpointUrl,
                             es.AuthType, es.AuthConfiguration, es.MethodDefinitionsJson, es.TimeoutSeconds);
                     }
+
+                    await _storage.DeleteExternalSystemsExceptAsync(
+                        command.ExternalSystems.Select(es => es.Name).ToList());
                 }
 
                 // Store database connection definitions
@@ -1901,6 +1917,9 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
                         await _storage.StoreDatabaseConnectionAsync(db.Name, db.ConnectionString,
                             db.MaxRetries, db.RetryDelay);
                     }
+
+                    await _storage.DeleteDatabaseConnectionsExceptAsync(
+                        command.DatabaseConnections.Select(db => db.Name).ToList());
                 }
 
                 // Notification lists and SMTP
@@ -1923,6 +1942,9 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
                             dc.BackupConfigurationJson, dc.FailoverRetryCount);
                     }
 
+                    var removedConnections = await _storage.DeleteDataConnectionDefinitionsExceptAsync(
+                        command.DataConnections.Select(dc => dc.Name).ToList());
+
                     // After the SQLite store, dispatch an
                     // internal message back to the actor thread so the DCL
                     // push runs through EnsureDclConnection — keeping the
@@ -1934,8 +1956,11 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
                     // self-contained after artifact deployment"). The
                     // helper's hash cache skips unchanged definitions, so
                     // the push is idempotent for re-deploys of the same
-                    // artifact bundle.
-                    self.Tell(new ApplyArtifactDataConnectionsToDcl(command.DataConnections));
+                    // artifact bundle. Reconciled removals ride the same
+                    // message so the live DCL connection actor is stopped
+                    // on the actor thread alongside the hash-cache eviction.
+                    self.Tell(new ApplyArtifactDataConnectionsToDcl(
+                        command.DataConnections, removedConnections));
                 }
 
                 // SMTP configuration is
@@ -2012,6 +2037,21 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
                 dc.BackupConfigurationJson,
                 dc.FailoverRetryCount);
         }
+
+        // Reconciled removals: the definition row is already gone from SQLite; evict
+        // the hash cache (so a later re-add with the same name recreates cleanly) and
+        // stop the live DCL connection actor. A connection still referenced by a
+        // deployed instance's config no longer exists centrally either — its attributes
+        // go bad quality, the standard disconnected signal, until the instance is
+        // redeployed against current central config.
+        foreach (var name in msg.RemovedConnectionNames)
+        {
+            _createdConnections.Remove(name);
+            _dclManager?.Tell(new DataConnectionLayer.Actors.RemoveConnectionCommand(name));
+            _logger.LogWarning(
+                "Artifact reconcile removed data connection '{Name}' (deleted centrally); " +
+                "its DCL connection actor has been stopped", name);
+        }
     }
 
     /// <summary>
@@ -2118,8 +2158,11 @@ public class DeploymentManagerActor : ReceiveActor, IWithTimers
     /// <see cref="HandleDeployArtifacts"/>'s off-thread persistence task back
     /// onto the actor thread, so the DCL push (and its hash-cache mutation)
     /// runs through <see cref="EnsureDclConnection"/> without crossing
-    /// thread-confinement boundaries.
+    /// thread-confinement boundaries. <paramref name="RemovedConnectionNames"/>
+    /// carries the reconcile-deleted definitions so the hash-cache eviction and
+    /// live DCL connection stop also happen actor-thread-confined.
     /// </summary>
     internal record ApplyArtifactDataConnectionsToDcl(
-        IReadOnlyList<Commons.Messages.Artifacts.DataConnectionArtifact> DataConnections);
+        IReadOnlyList<Commons.Messages.Artifacts.DataConnectionArtifact> DataConnections,
+        IReadOnlyList<string> RemovedConnectionNames);
 }

src/ZB.MOM.WW.ScadaBridge.SiteRuntime/Persistence/SiteStorageService.cs

@@ -760,6 +760,93 @@ public class SiteStorageService
 
         return results;
     }
+
+    // ── Artifact set reconciliation ──
+
+    /// <summary>
+    /// Deletes shared scripts absent from the supplied full set and returns the deleted names.
+    /// </summary>
+    /// <param name="keepNames">The complete set of shared script names that should exist.</param>
+    /// <returns>A task that resolves to the names of the rows that were deleted.</returns>
+    public Task<List<string>> DeleteSharedScriptsExceptAsync(IReadOnlyCollection<string> keepNames)
+        => DeleteRowsExceptAsync("shared_scripts", keepNames);
+
+    /// <summary>
+    /// Deletes external system definitions absent from the supplied full set and returns the deleted names.
+    /// </summary>
+    /// <param name="keepNames">The complete set of external system names that should exist.</param>
+    /// <returns>A task that resolves to the names of the rows that were deleted.</returns>
+    public Task<List<string>> DeleteExternalSystemsExceptAsync(IReadOnlyCollection<string> keepNames)
+        => DeleteRowsExceptAsync("external_systems", keepNames);
+
+    /// <summary>
+    /// Deletes database connection definitions absent from the supplied full set and returns the deleted names.
+    /// </summary>
+    /// <param name="keepNames">The complete set of database connection names that should exist.</param>
+    /// <returns>A task that resolves to the names of the rows that were deleted.</returns>
+    public Task<List<string>> DeleteDatabaseConnectionsExceptAsync(IReadOnlyCollection<string> keepNames)
+        => DeleteRowsExceptAsync("database_connections", keepNames);
+
+    /// <summary>
+    /// Deletes data connection definitions absent from the supplied full set and returns the deleted names.
+    /// </summary>
+    /// <param name="keepNames">The complete set of data connection names that should exist.</param>
+    /// <returns>A task that resolves to the names of the rows that were deleted.</returns>
+    public Task<List<string>> DeleteDataConnectionDefinitionsExceptAsync(IReadOnlyCollection<string> keepNames)
+        => DeleteRowsExceptAsync("data_connection_definitions", keepNames);
+
+    /// <summary>
+    /// Deletes every row of an artifact table whose <c>name</c> is not in
+    /// <paramref name="keepNames"/>, returning the deleted names.
+    ///
+    /// Central always ships the COMPLETE system-wide set of each artifact class on an
+    /// artifact deployment, so a stored row absent from the incoming set means the
+    /// artifact was deleted centrally. The store methods are upsert-only, which used to
+    /// leave such rows orphaned on the site forever (a centrally-deleted external
+    /// system stayed callable from site scripts indefinitely); the artifact apply now
+    /// reconciles by calling this after upserting. An empty <paramref name="keepNames"/>
+    /// legitimately deletes every row — central saying "none of these exist anymore".
+    /// </summary>
+    private async Task<List<string>> DeleteRowsExceptAsync(string table, IReadOnlyCollection<string> keepNames)
+    {
+        await using var connection = OpenConnection();
+        await using var transaction = connection.BeginTransaction();
+
+        var keepParams = keepNames.Select((name, i) => (Key: $"@k{i}", Value: name)).ToList();
+        var predicate = keepParams.Count == 0
+            ? string.Empty
+            : $" WHERE name NOT IN ({string.Join(", ", keepParams.Select(p => p.Key))})";
+
+        var removed = new List<string>();
+        await using (var select = connection.CreateCommand())
+        {
+            select.Transaction = transaction;
+            select.CommandText = $"SELECT name FROM {table}{predicate}";
+            foreach (var (key, value) in keepParams)
+                select.Parameters.AddWithValue(key, value);
+
+            await using var reader = await select.ExecuteReaderAsync();
+            while (await reader.ReadAsync())
+                removed.Add(reader.GetString(0));
+        }
+
+        if (removed.Count > 0)
+        {
+            await using var delete = connection.CreateCommand();
+            delete.Transaction = transaction;
+            delete.CommandText = $"DELETE FROM {table}{predicate}";
+            foreach (var (key, value) in keepParams)
+                delete.Parameters.AddWithValue(key, value);
+
+            await delete.ExecuteNonQueryAsync();
+            _logger.LogInformation(
+                "Artifact reconcile removed {Count} orphaned row(s) from {Table}: {Names}",
+                removed.Count, table, string.Join(", ", removed));
+        }
+
+        transaction.Commit();
+        return removed;
+    }
 }
 
 /// <summary>