docs: complete XML doc comments via fixdocs (2757 to 131 findings)

Add missing <returns>/<param>/<summary>/<typeparam> tags and clean up
misused inheritdoc across 481 files so the documented API surface is
complete. Documentation-only (zero code lines changed). The 131 remaining
findings are inheritdoc-style warnings deliberately left to preserve
hand-written implementation rationale (plan-decision notes, race-condition
explanations).

src/Client/ZB.MOM.WW.OtOpcUa.Client.CLI/CommandBase.cs

@@ -67,11 +67,13 @@ public abstract class CommandBase : ICommand
     /// Executes the command-specific workflow against the configured OPC UA endpoint.
     /// </summary>
     /// <param name="console">The CLI console used for output and cancellation handling.</param>
+    /// <returns>A value task that represents the asynchronous command execution.</returns>
     public abstract ValueTask ExecuteAsync(IConsole console);
 
     /// <summary>
     ///     Creates a <see cref="ConnectionSettings" /> from the common command options.
     /// </summary>
+    /// <returns>A <see cref="ConnectionSettings"/> populated from the current command option values.</returns>
     protected ConnectionSettings CreateConnectionSettings()
     {
         var securityMode = SecurityModeMapper.FromString(Security);
@@ -97,6 +99,7 @@ public abstract class CommandBase : ICommand
     ///     and returns both the service and the connection info.
     /// </summary>
     /// <param name="ct">The cancellation token that aborts connection setup for the command.</param>
+    /// <returns>A tuple of the connected <see cref="IOpcUaClientService"/> and the resulting <see cref="ConnectionInfo"/>.</returns>
     protected async Task<(IOpcUaClientService Service, ConnectionInfo Info)> CreateServiceAndConnectAsync(
         CancellationToken ct)
     {

src/Client/ZB.MOM.WW.OtOpcUa.Client.Shared/Adapters/DefaultApplicationConfigurationFactory.cs

@@ -12,9 +12,7 @@ internal sealed class DefaultApplicationConfigurationFactory : IApplicationConfi
 {
     private static readonly ILogger Logger = Log.ForContext<DefaultApplicationConfigurationFactory>();
 
-    /// <summary>Creates an OPC UA application configuration from the provided connection settings.</summary>
+    /// <inheritdoc />
-    /// <param name="settings">The connection settings to use.</param>
-    /// <param name="ct">Token to cancel the operation.</param>
     public async Task<ApplicationConfiguration> CreateAsync(ConnectionSettings settings, CancellationToken ct)
     {
         // Resolve the canonical PKI path lazily on first use so constructing a

src/Client/ZB.MOM.WW.OtOpcUa.Client.Shared/Adapters/DefaultEndpointDiscovery.cs

@@ -11,10 +11,7 @@ internal sealed class DefaultEndpointDiscovery : IEndpointDiscovery
 {
     private static readonly ILogger Logger = Log.ForContext<DefaultEndpointDiscovery>();
 
-    /// <summary>Selects an OPC UA endpoint matching the requested security mode.</summary>
+    /// <inheritdoc />
-    /// <param name="config">The application configuration.</param>
-    /// <param name="endpointUrl">The endpoint URL to query.</param>
-    /// <param name="requestedMode">The requested message security mode.</param>
     public EndpointDescription SelectEndpoint(ApplicationConfiguration config, string endpointUrl,
         MessageSecurityMode requestedMode)
     {
@@ -53,6 +50,7 @@ internal static class EndpointSelector
     ///     Thrown when no endpoint matches <paramref name="requestedMode"/>; the message lists the
     ///     security mode + policy combinations the server returned so operators can diagnose mismatches.
     /// </exception>
+    /// <returns>The best matching <see cref="EndpointDescription"/> with its URL rewritten to the requested host.</returns>
     public static EndpointDescription SelectBest(
         IEnumerable<EndpointDescription> allEndpoints,
         string endpointUrl,

src/Client/ZB.MOM.WW.OtOpcUa.Client.Shared/Adapters/IApplicationConfigurationFactory.cs

@@ -13,5 +13,6 @@ internal interface IApplicationConfigurationFactory
     /// </summary>
     /// <param name="settings">The connection settings to configure.</param>
     /// <param name="ct">Cancellation token for the operation.</param>
+    /// <returns>A task that resolves to the validated <see cref="ApplicationConfiguration"/>.</returns>
     Task<ApplicationConfiguration> CreateAsync(ConnectionSettings settings, CancellationToken ct = default);
 }

src/Client/ZB.MOM.WW.OtOpcUa.Client.Shared/Adapters/IEndpointDiscovery.cs

@@ -14,6 +14,7 @@ internal interface IEndpointDiscovery
     /// <param name="config">The OPC UA application configuration.</param>
     /// <param name="endpointUrl">The endpoint URL to discover.</param>
     /// <param name="requestedMode">The requested message security mode.</param>
+    /// <returns>The best matching endpoint description for the requested security mode.</returns>
     EndpointDescription SelectEndpoint(ApplicationConfiguration config, string endpointUrl,
         MessageSecurityMode requestedMode);
 }

src/Client/ZB.MOM.WW.OtOpcUa.Client.Shared/Adapters/ISessionAdapter.cs

@@ -58,6 +58,7 @@ internal interface ISessionAdapter : IDisposable
     /// </summary>
     /// <param name="nodeId">The node whose current runtime value should be read.</param>
     /// <param name="ct">The cancellation token that aborts the server read if the client cancels the request.</param>
+    /// <returns>A task that resolves to the current <see cref="DataValue"/> for the node.</returns>
     Task<DataValue> ReadValueAsync(NodeId nodeId, CancellationToken ct = default);
 
     /// <summary>
@@ -66,6 +67,7 @@ internal interface ISessionAdapter : IDisposable
     /// <param name="nodeId">The node whose value should be updated.</param>
     /// <param name="value">The typed OPC UA data value to write to the server.</param>
     /// <param name="ct">The cancellation token that aborts the write if the client cancels the request.</param>
+    /// <returns>A task that resolves to the OPC UA <see cref="StatusCode"/> for the write operation.</returns>
     Task<StatusCode> WriteValueAsync(NodeId nodeId, DataValue value, CancellationToken ct = default);
 
     /// <summary>
@@ -75,6 +77,7 @@ internal interface ISessionAdapter : IDisposable
     /// <param name="nodeId">The starting node for the hierarchical browse.</param>
     /// <param name="nodeClassMask">The node classes that should be returned to the caller.</param>
     /// <param name="ct">The cancellation token that aborts the browse request.</param>
+    /// <returns>A task that resolves to a tuple of an optional continuation point and the returned references.</returns>
     Task<(byte[]? ContinuationPoint, ReferenceDescriptionCollection References)> BrowseAsync(
         NodeId nodeId, uint nodeClassMask = 0, CancellationToken ct = default);
 
@@ -83,6 +86,7 @@ internal interface ISessionAdapter : IDisposable
     /// </summary>
     /// <param name="continuationPoint">The continuation token returned by a prior browse result page.</param>
     /// <param name="ct">The cancellation token that aborts the browse-next request.</param>
+    /// <returns>A task that resolves to a tuple of an optional next continuation point and the returned references.</returns>
     Task<(byte[]? ContinuationPoint, ReferenceDescriptionCollection References)> BrowseNextAsync(
         byte[] continuationPoint, CancellationToken ct = default);
 
@@ -91,6 +95,7 @@ internal interface ISessionAdapter : IDisposable
     /// </summary>
     /// <param name="nodeId">The node to inspect for child objects or variables.</param>
     /// <param name="ct">The cancellation token that aborts the child lookup.</param>
+    /// <returns>A task that resolves to <see langword="true"/> if the node has at least one child; otherwise <see langword="false"/>.</returns>
     Task<bool> HasChildrenAsync(NodeId nodeId, CancellationToken ct = default);
 
     /// <summary>
@@ -101,6 +106,7 @@ internal interface ISessionAdapter : IDisposable
     /// <param name="endTime">The inclusive end of the requested history window.</param>
     /// <param name="maxValues">The maximum number of raw samples to return to the client.</param>
     /// <param name="ct">The cancellation token that aborts the history read.</param>
+    /// <returns>A task that resolves to the ordered list of raw historical data values.</returns>
     Task<IReadOnlyList<DataValue>> HistoryReadRawAsync(NodeId nodeId, DateTime startTime, DateTime endTime,
         int maxValues, CancellationToken ct = default);
 
@@ -113,6 +119,7 @@ internal interface ISessionAdapter : IDisposable
     /// <param name="aggregateId">The OPC UA aggregate function to evaluate over the history window.</param>
     /// <param name="intervalMs">The processing interval, in milliseconds, for each aggregate bucket.</param>
     /// <param name="ct">The cancellation token that aborts the aggregate history read.</param>
+    /// <returns>A task that resolves to the ordered list of processed aggregate data values.</returns>
     Task<IReadOnlyList<DataValue>> HistoryReadAggregateAsync(NodeId nodeId, DateTime startTime, DateTime endTime,
         NodeId aggregateId, double intervalMs, CancellationToken ct = default);
 
@@ -121,6 +128,7 @@ internal interface ISessionAdapter : IDisposable
     /// </summary>
     /// <param name="publishingIntervalMs">The requested publishing interval for monitored items on the new subscription.</param>
     /// <param name="ct">The cancellation token that aborts subscription creation.</param>
+    /// <returns>A task that resolves to the newly created <see cref="ISubscriptionAdapter"/>.</returns>
     Task<ISubscriptionAdapter> CreateSubscriptionAsync(int publishingIntervalMs, CancellationToken ct = default);
 
     /// <summary>
@@ -130,11 +138,13 @@ internal interface ISessionAdapter : IDisposable
     /// <param name="methodId">The method node to invoke.</param>
     /// <param name="inputArguments">The ordered input arguments supplied to the server method call.</param>
     /// <param name="ct">The cancellation token that aborts the method invocation.</param>
+    /// <returns>A task that resolves to the list of output arguments returned by the method, or <see langword="null"/> if none.</returns>
     Task<IList<object>?> CallMethodAsync(NodeId objectId, NodeId methodId, object[] inputArguments, CancellationToken ct = default);
 
     /// <summary>
     /// Closes the underlying session gracefully before the adapter is disposed or replaced during failover.
     /// </summary>
     /// <param name="ct">The cancellation token that aborts the close request.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task CloseAsync(CancellationToken ct = default);
 }

src/Client/ZB.MOM.WW.OtOpcUa.Client.Shared/Adapters/ISubscriptionAdapter.cs

@@ -28,6 +28,7 @@ internal interface ISubscriptionAdapter : IDisposable
     /// </summary>
     /// <param name="clientHandle">The client handle returned when the monitored item was created.</param>
     /// <param name="ct">The cancellation token that aborts the monitored-item removal.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task RemoveMonitoredItemAsync(uint clientHandle, CancellationToken ct = default);
 
     /// <summary>
@@ -46,11 +47,13 @@ internal interface ISubscriptionAdapter : IDisposable
     ///     Requests a condition refresh for this subscription.
     /// </summary>
     /// <param name="ct">The cancellation token that aborts the condition refresh request.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task ConditionRefreshAsync(CancellationToken ct = default);
 
     /// <summary>
     ///     Removes all monitored items and deletes the subscription.
     /// </summary>
     /// <param name="ct">The cancellation token that aborts subscription deletion.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task DeleteAsync(CancellationToken ct = default);
 }

src/Client/ZB.MOM.WW.OtOpcUa.Client.Shared/ClientStoragePaths.cs

@@ -28,6 +28,7 @@ public static class ClientStoragePaths
     ///     one-shot legacy-folder migration before returning so callers that depend on this
     ///     path (PKI store, settings file) find their existing state at the canonical name.
     /// </summary>
+    /// <returns>The absolute path to the client's top-level folder under LocalApplicationData.</returns>
     public static string GetRoot()
     {
         var localAppData = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);
@@ -37,6 +38,7 @@ public static class ClientStoragePaths
     }
 
     /// <summary>Subfolder for the application's PKI store — used by both CLI + UI.</summary>
+    /// <returns>The absolute path to the PKI store subfolder.</returns>
     public static string GetPkiPath() => Path.Combine(GetRoot(), "pki");
 
     /// <summary>
@@ -45,6 +47,7 @@ public static class ClientStoragePaths
     ///     folder existed + was moved to canonical, false when no migration was needed or
     ///     canonical was already present.
     /// </summary>
+    /// <returns><see langword="true"/> when the legacy folder was found and moved; <see langword="false"/> when no migration was needed.</returns>
     public static bool TryRunLegacyMigration()
     {
         var localAppData = Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData);

src/Client/ZB.MOM.WW.OtOpcUa.Client.Shared/IOpcUaClientService.cs

@@ -24,12 +24,14 @@ public interface IOpcUaClientService : IDisposable
     /// </summary>
     /// <param name="settings">The endpoint, security, and authentication settings used to establish the session.</param>
     /// <param name="ct">The cancellation token that aborts the connect workflow.</param>
+    /// <returns>A <see cref="ConnectionInfo"/> describing the active session after a successful connect.</returns>
     Task<ConnectionInfo> ConnectAsync(ConnectionSettings settings, CancellationToken ct = default);
 
     /// <summary>
     /// Disconnects from the active OPC UA endpoint and tears down subscriptions owned by the client.
     /// </summary>
     /// <param name="ct">The cancellation token that aborts disconnect cleanup.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task DisconnectAsync(CancellationToken ct = default);
 
     /// <summary>
@@ -37,6 +39,7 @@ public interface IOpcUaClientService : IDisposable
     /// </summary>
     /// <param name="nodeId">The node whose value should be retrieved.</param>
     /// <param name="ct">The cancellation token that aborts the read request.</param>
+    /// <returns>The current <see cref="DataValue"/> including value, status code, and timestamps.</returns>
     Task<DataValue> ReadValueAsync(NodeId nodeId, CancellationToken ct = default);
 
     /// <summary>
@@ -45,6 +48,7 @@ public interface IOpcUaClientService : IDisposable
     /// <param name="nodeId">The node whose value should be updated.</param>
     /// <param name="value">The raw value supplied by the CLI or UI workflow.</param>
     /// <param name="ct">The cancellation token that aborts the write request.</param>
+    /// <returns>The OPC UA <see cref="StatusCode"/> returned by the server for the write operation.</returns>
     Task<StatusCode> WriteValueAsync(NodeId nodeId, object value, CancellationToken ct = default);
 
     /// <summary>
@@ -52,6 +56,7 @@ public interface IOpcUaClientService : IDisposable
     /// </summary>
     /// <param name="parentNodeId">The node to browse, or <see cref="ObjectIds.ObjectsFolder"/> when omitted.</param>
     /// <param name="ct">The cancellation token that aborts the browse request.</param>
+    /// <returns>The list of child nodes discovered under the specified parent.</returns>
     Task<IReadOnlyList<BrowseResult>> BrowseAsync(NodeId? parentNodeId = null, CancellationToken ct = default);
 
     /// <summary>
@@ -60,6 +65,7 @@ public interface IOpcUaClientService : IDisposable
     /// <param name="nodeId">The node whose value changes should be monitored.</param>
     /// <param name="intervalMs">The monitored-item sampling and publishing interval in milliseconds.</param>
     /// <param name="ct">The cancellation token that aborts subscription creation.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task SubscribeAsync(NodeId nodeId, int intervalMs = 1000, CancellationToken ct = default);
 
     /// <summary>
@@ -67,6 +73,7 @@ public interface IOpcUaClientService : IDisposable
     /// </summary>
     /// <param name="nodeId">The node whose live-data subscription should be removed.</param>
     /// <param name="ct">The cancellation token that aborts the unsubscribe request.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task UnsubscribeAsync(NodeId nodeId, CancellationToken ct = default);
 
     /// <summary>
@@ -75,18 +82,21 @@ public interface IOpcUaClientService : IDisposable
     /// <param name="sourceNodeId">The event source to monitor, or the server object when omitted.</param>
     /// <param name="intervalMs">The publishing interval in milliseconds for the alarm subscription.</param>
     /// <param name="ct">The cancellation token that aborts alarm subscription creation.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task SubscribeAlarmsAsync(NodeId? sourceNodeId = null, int intervalMs = 1000, CancellationToken ct = default);
 
     /// <summary>
     /// Removes the active alarm subscription.
     /// </summary>
     /// <param name="ct">The cancellation token that aborts alarm subscription cleanup.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task UnsubscribeAlarmsAsync(CancellationToken ct = default);
 
     /// <summary>
     /// Requests retained alarm conditions again so a client can repopulate its alarm list after reconnecting.
     /// </summary>
     /// <param name="ct">The cancellation token that aborts the condition refresh request.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task RequestConditionRefreshAsync(CancellationToken ct = default);
 
     /// <summary>
@@ -111,6 +121,7 @@ public interface IOpcUaClientService : IDisposable
     /// <param name="endTime">The inclusive end of the requested history range.</param>
     /// <param name="maxValues">The maximum number of raw values to return.</param>
     /// <param name="ct">The cancellation token that aborts the history read.</param>
+    /// <returns>The raw historical <see cref="DataValue"/> samples in the requested range.</returns>
     Task<IReadOnlyList<DataValue>> HistoryReadRawAsync(NodeId nodeId, DateTime startTime, DateTime endTime,
         int maxValues = 1000, CancellationToken ct = default);
 
@@ -123,6 +134,7 @@ public interface IOpcUaClientService : IDisposable
     /// <param name="aggregate">The aggregate function the operator selected for processed history.</param>
     /// <param name="intervalMs">The processing interval, in milliseconds, for each aggregate bucket.</param>
     /// <param name="ct">The cancellation token that aborts the processed history request.</param>
+    /// <returns>The processed historical <see cref="DataValue"/> samples computed by the requested aggregate.</returns>
     Task<IReadOnlyList<DataValue>> HistoryReadAggregateAsync(NodeId nodeId, DateTime startTime, DateTime endTime,
         AggregateType aggregate, double intervalMs = 3600000, CancellationToken ct = default);
 
@@ -130,6 +142,7 @@ public interface IOpcUaClientService : IDisposable
     /// Reads redundancy status data such as redundancy mode, service level, and partner endpoint URIs.
     /// </summary>
     /// <param name="ct">The cancellation token that aborts redundancy inspection.</param>
+    /// <returns>A <see cref="RedundancyInfo"/> snapshot containing redundancy mode, service level, and partner endpoint URIs.</returns>
     Task<RedundancyInfo> GetRedundancyInfoAsync(CancellationToken ct = default);
 
     /// <summary>

src/Client/ZB.MOM.WW.OtOpcUa.Client.Shared/OpcUaClientService.cs

@@ -73,13 +73,13 @@ public sealed class OpcUaClientService : IOpcUaClientService
     {
     }
 
-    /// <inheritdoc />
+    /// <summary>Raised when subscribed node values change.</summary>
     public event EventHandler<DataChangedEventArgs>? DataChanged;
 
-    /// <inheritdoc />
+    /// <summary>Raised when an alarm event is received from the server.</summary>
     public event EventHandler<AlarmEventArgs>? AlarmEvent;
 
-    /// <inheritdoc />
+    /// <summary>Raised when the connection state changes.</summary>
     public event EventHandler<ConnectionStateChangedEventArgs>? ConnectionStateChanged;
 
     /// <inheritdoc />

src/Client/ZB.MOM.WW.OtOpcUa.Client.UI/Services/AvaloniaUiDispatcher.cs

@@ -7,8 +7,7 @@ namespace ZB.MOM.WW.OtOpcUa.Client.UI.Services;
 /// </summary>
 public sealed class AvaloniaUiDispatcher : IUiDispatcher
 {
-    /// <summary>Posts an action to the Avalonia UI thread for execution.</summary>
+    /// <inheritdoc />
-    /// <param name="action">The action to execute on the UI thread.</param>
     public void Post(Action action)
     {
         Dispatcher.UIThread.Post(action);

src/Client/ZB.MOM.WW.OtOpcUa.Client.UI/Services/ISettingsService.cs

@@ -6,6 +6,7 @@ namespace ZB.MOM.WW.OtOpcUa.Client.UI.Services;
 public interface ISettingsService
 {
     /// <summary>Loads user settings from persistent storage.</summary>
+    /// <returns>The persisted <see cref="UserSettings"/>, or a default instance if none are saved.</returns>
     UserSettings Load();
     /// <summary>Saves user settings to persistent storage.</summary>
     /// <param name="settings">The settings to save.</param>

src/Client/ZB.MOM.WW.OtOpcUa.Client.UI/Services/JsonSettingsService.cs

@@ -19,8 +19,7 @@ public sealed class JsonSettingsService : ISettingsService
         WriteIndented = true
     };
 
-    /// <summary>Loads user settings from the settings file.</summary>
+    /// <inheritdoc />
-    /// <returns>The loaded user settings, or a new default instance if load fails.</returns>
     public UserSettings Load()
     {
         try
@@ -37,8 +36,7 @@ public sealed class JsonSettingsService : ISettingsService
         }
     }
 
-    /// <summary>Saves user settings to the settings file.</summary>
+    /// <inheritdoc />
-    /// <param name="settings">The user settings to save.</param>
     public void Save(UserSettings settings)
     {
         try

src/Client/ZB.MOM.WW.OtOpcUa.Client.UI/Services/SynchronousUiDispatcher.cs

@@ -6,8 +6,7 @@ namespace ZB.MOM.WW.OtOpcUa.Client.UI.Services;
 /// </summary>
 public sealed class SynchronousUiDispatcher : IUiDispatcher
 {
-    /// <summary>Executes the action synchronously on the calling thread.</summary>
+    /// <inheritdoc />
-    /// <param name="action">The action to execute.</param>
     public void Post(Action action)
     {
         action();

src/Client/ZB.MOM.WW.OtOpcUa.Client.UI/ViewModels/AlarmsViewModel.cs

@@ -195,6 +195,7 @@ public partial class AlarmsViewModel : ObservableObject
     /// <summary>
     ///     Returns the monitored node ID for persistence, or null if not subscribed.
     /// </summary>
+    /// <returns>The monitored node ID string, or null if not currently subscribed.</returns>
     public string? GetAlarmSourceNodeId()
     {
         return IsSubscribed ? MonitoredNodeIdText : null;

src/Client/ZB.MOM.WW.OtOpcUa.Client.UI/ViewModels/BrowseTreeViewModel.cs

@@ -30,6 +30,7 @@ public class BrowseTreeViewModel : ObservableObject
     /// <summary>
     ///     Loads root nodes by browsing with a null parent.
     /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public async Task LoadRootsAsync()
     {
         var results = await _service.BrowseAsync();

src/Client/ZB.MOM.WW.OtOpcUa.Client.UI/ViewModels/SubscriptionsViewModel.cs

@@ -143,6 +143,7 @@ public partial class SubscriptionsViewModel : ObservableObject
     /// </summary>
     /// <param name="nodeIdStr">The node ID to subscribe to from the browse tree or persisted settings.</param>
     /// <param name="intervalMs">The monitored-item interval, in milliseconds, for the subscription.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public async Task AddSubscriptionForNodeAsync(string nodeIdStr, int intervalMs = 1000)
     {
         if (!IsConnected || string.IsNullOrWhiteSpace(nodeIdStr)) return;
@@ -176,6 +177,7 @@ public partial class SubscriptionsViewModel : ObservableObject
     /// <param name="nodeIdStr">The root node whose variables should be subscribed recursively.</param>
     /// <param name="nodeClass">The node class of the starting node so variables can be subscribed immediately.</param>
     /// <param name="intervalMs">The monitored-item interval, in milliseconds, used for created subscriptions.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public Task AddSubscriptionRecursiveAsync(string nodeIdStr, string nodeClass, int intervalMs = 1000)
     {
         return AddSubscriptionRecursiveAsync(nodeIdStr, nodeClass, intervalMs, maxDepth: 10, currentDepth: 0);
@@ -211,6 +213,7 @@ public partial class SubscriptionsViewModel : ObservableObject
     /// <summary>
     ///     Returns the node IDs of all active subscriptions for persistence.
     /// </summary>
+    /// <returns>The list of node ID strings for all currently active subscriptions.</returns>
     public List<string> GetSubscribedNodeIds()
     {
         return ActiveSubscriptions.Select(s => s.NodeId).ToList();
@@ -220,6 +223,7 @@ public partial class SubscriptionsViewModel : ObservableObject
     ///     Restores subscriptions from a saved list of node IDs.
     /// </summary>
     /// <param name="nodeIds">The node IDs persisted from a prior UI session.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public async Task RestoreSubscriptionsAsync(IEnumerable<string> nodeIds)
     {
         foreach (var nodeId in nodeIds)
@@ -232,6 +236,7 @@ public partial class SubscriptionsViewModel : ObservableObject
     /// </summary>
     /// <param name="nodeIdStr">The node ID the operator wants to write.</param>
     /// <param name="rawValue">The raw text value entered by the operator.</param>
+    /// <returns>A tuple of (success flag, operator-readable message) describing the outcome of the write.</returns>
     public async Task<(bool Success, string Message)> ValidateAndWriteAsync(string nodeIdStr, string rawValue)
     {
         try

src/Core/ZB.MOM.WW.OtOpcUa.Cluster/ClusterRoleInfo.cs

@@ -43,20 +43,16 @@ public sealed class ClusterRoleInfo : IClusterRoleInfo, IDisposable
         _subscriber = system.ActorOf(Props.Create(() => new SubscriberActor(this)), "clusterroleinfo-subscriber");
     }
 
-    /// <summary>Gets the local cluster node identifier.</summary>
+    /// <inheritdoc />
     public CommonsNodeId LocalNode => _localNode;
 
-    /// <summary>Gets the set of roles assigned to the local node.</summary>
+    /// <inheritdoc />
     public IReadOnlySet<string> LocalRoles => _localRoles;
 
-    /// <summary>Checks if the local node has a specific role.</summary>
+    /// <inheritdoc />
-    /// <param name="role">The role name to check.</param>
-    /// <returns>True if the local node has the specified role; otherwise false.</returns>
     public bool HasRole(string role) => _localRoles.Contains(role);
 
-    /// <summary>Gets all cluster members that have a specific role.</summary>
+    /// <inheritdoc />
-    /// <param name="role">The role name.</param>
-    /// <returns>A read-only list of node IDs with the specified role.</returns>
     public IReadOnlyList<CommonsNodeId> MembersWithRole(string role)
     {
         lock (_lock)
@@ -68,9 +64,7 @@ public sealed class ClusterRoleInfo : IClusterRoleInfo, IDisposable
         }
     }
 
-    /// <summary>Gets the current leader node for a specific role.</summary>
+    /// <inheritdoc />
-    /// <param name="role">The role name.</param>
-    /// <returns>The node ID of the current role leader, or null if no leader is elected.</returns>
     public CommonsNodeId? RoleLeader(string role)
     {
         lock (_lock)

src/Core/ZB.MOM.WW.OtOpcUa.Cluster/RoleParser.cs

@@ -9,6 +9,7 @@ public static class RoleParser
 
     /// <summary>Parses a comma-separated string of role names into a validated array.</summary>
     /// <param name="raw">The raw role string to parse.</param>
+    /// <returns>An array of validated, distinct, lower-cased role names; empty array when the input is null or whitespace.</returns>
     public static string[] Parse(string? raw)
     {
         if (string.IsNullOrWhiteSpace(raw)) return Array.Empty<string>();

src/Core/ZB.MOM.WW.OtOpcUa.Cluster/ServiceCollectionExtensions.cs

@@ -18,6 +18,7 @@ public static class ServiceCollectionExtensions
     /// </summary>
     /// <param name="services">The service collection to configure.</param>
     /// <param name="configuration">The application configuration containing cluster options.</param>
+    /// <returns>The same <see cref="IServiceCollection"/> for chaining.</returns>
     public static IServiceCollection AddOtOpcUaCluster(this IServiceCollection services, IConfiguration configuration)
     {
         services.AddOptions<AkkaClusterOptions>()
@@ -45,6 +46,7 @@ public static class ServiceCollectionExtensions
     /// </summary>
     /// <param name="builder">The Akka configuration builder to configure.</param>
     /// <param name="serviceProvider">The service provider for resolving cluster options.</param>
+    /// <returns>The same <see cref="AkkaConfigurationBuilder"/> for chaining.</returns>
     public static AkkaConfigurationBuilder WithOtOpcUaClusterBootstrap(
         this AkkaConfigurationBuilder builder,
         IServiceProvider serviceProvider)

src/Core/ZB.MOM.WW.OtOpcUa.Commons/Browsing/IBrowseSession.cs

@@ -16,14 +16,22 @@ public interface IBrowseSession : IAsyncDisposable
     DateTime LastUsedUtc { get; }
 
     /// <summary>Returns the top-level browse nodes.</summary>
+    /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>A task that resolves to the list of top-level browse nodes.</returns>
     Task<IReadOnlyList<BrowseNode>> RootAsync(CancellationToken cancellationToken);
 
     /// <summary>Returns the direct children of the node identified by
     /// <paramref name="nodeId"/>.</summary>
+    /// <param name="nodeId">The identifier of the node whose children to expand.</param>
+    /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>A task that resolves to the list of direct child nodes.</returns>
     Task<IReadOnlyList<BrowseNode>> ExpandAsync(string nodeId, CancellationToken cancellationToken);
 
     /// <summary>Returns the attributes of the node identified by <paramref name="nodeId"/>.
     /// Empty for drivers whose tree is uniform (OPC UA Client). Galaxy uses this to populate
     /// the attribute side-panel after the user selects an object.</summary>
+    /// <param name="nodeId">The identifier of the node whose attributes to retrieve.</param>
+    /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>A task that resolves to the list of attribute descriptors for the node.</returns>
     Task<IReadOnlyList<AttributeInfo>> AttributesAsync(string nodeId, CancellationToken cancellationToken);
 }

src/Core/ZB.MOM.WW.OtOpcUa.Commons/Browsing/IDriverBrowser.cs

@@ -15,5 +15,6 @@ public interface IDriverBrowser
     /// <param name="configJson">Driver options serialized as JSON; same shape the runtime
     /// driver would consume.</param>
     /// <param name="cancellationToken">Cancellation for the connect phase only.</param>
+    /// <returns>A task containing the opened browse session.</returns>
     Task<IBrowseSession> OpenAsync(string configJson, CancellationToken cancellationToken);
 }

src/Core/ZB.MOM.WW.OtOpcUa.Commons/Engines/IAlarmActorStateStore.cs

@@ -18,6 +18,7 @@ public interface IAlarmActorStateStore
     /// <summary>Saves the alarm actor state snapshot.</summary>
     /// <param name="snapshot">The state snapshot to persist.</param>
     /// <param name="ct">Cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task SaveAsync(AlarmActorStateSnapshot snapshot, CancellationToken ct);
 }
 
@@ -41,14 +42,10 @@ public sealed class NullAlarmActorStateStore : IAlarmActorStateStore
 {
     public static readonly NullAlarmActorStateStore Instance = new();
     private NullAlarmActorStateStore() { }
-    /// <summary>Always returns null, indicating no persisted state.</summary>
+    /// <inheritdoc />
-    /// <param name="alarmId">The alarm identifier (unused).</param>
-    /// <param name="ct">Cancellation token (unused).</param>
     public Task<AlarmActorStateSnapshot?> LoadAsync(string alarmId, CancellationToken ct) =>
         Task.FromResult<AlarmActorStateSnapshot?>(null);
-    /// <summary>Completes immediately without persisting anything.</summary>
+    /// <inheritdoc />
-    /// <param name="snapshot">The state snapshot (ignored).</param>
-    /// <param name="ct">Cancellation token (unused).</param>
     public Task SaveAsync(AlarmActorStateSnapshot snapshot, CancellationToken ct) =>
         Task.CompletedTask;
 }

src/Core/ZB.MOM.WW.OtOpcUa.Commons/Engines/IVirtualTagEvaluator.cs

@@ -43,11 +43,7 @@ public sealed class NullVirtualTagEvaluator : IVirtualTagEvaluator
 {
     public static readonly NullVirtualTagEvaluator Instance = new();
     private NullVirtualTagEvaluator() { }
-    /// <summary>Returns <see cref="VirtualTagEvalResult.NoChange"/> for every evaluation.</summary>
+    /// <inheritdoc />
-    /// <param name="virtualTagId">The virtual tag identifier (ignored).</param>
-    /// <param name="expression">The expression string (ignored).</param>
-    /// <param name="dependencies">The variable dependencies (ignored).</param>
-    /// <returns>Always returns <see cref="VirtualTagEvalResult.NoChange"/>.</returns>
     public VirtualTagEvalResult Evaluate(string virtualTagId, string expression, IReadOnlyDictionary<string, object?> dependencies)
         => VirtualTagEvalResult.NoChange;
 }

src/Core/ZB.MOM.WW.OtOpcUa.Commons/Interfaces/IAdminOperationsClient.cs

@@ -23,5 +23,6 @@ public interface IAdminOperationsClient
     /// <typeparam name="T">Expected reply type.</typeparam>
     /// <param name="message">The message to send.</param>
     /// <param name="ct">Cancellation token (caller-controlled timeout).</param>
+    /// <returns>A task that resolves to the reply of type <typeparamref name="T"/>.</returns>
     Task<T> AskAsync<T>(object message, CancellationToken ct);
 }

src/Core/ZB.MOM.WW.OtOpcUa.Commons/Interfaces/IFleetDiagnosticsClient.cs

@@ -11,5 +11,6 @@ public interface IFleetDiagnosticsClient
     /// <summary>Gets diagnostics for the specified node.</summary>
     /// <param name="nodeId">The node ID to retrieve diagnostics for.</param>
     /// <param name="ct">The cancellation token.</param>
+    /// <returns>A task that resolves to the diagnostics snapshot for the specified node.</returns>
     Task<NodeDiagnosticsSnapshot> GetDiagnosticsAsync(NodeId nodeId, CancellationToken ct);
 }

src/Core/ZB.MOM.WW.OtOpcUa.Commons/Observability/OtOpcUaTelemetry.cs

@@ -69,6 +69,7 @@ public static class OtOpcUaTelemetry
     /// null when no listener is attached so the call site stays cheap on undecorated builds.
     /// </summary>
     /// <param name="deploymentId">The deployment identifier to tag the span with.</param>
+    /// <returns>The started <see cref="Activity"/>, or null when no listener is attached.</returns>
     public static Activity? StartDeployApplySpan(string deploymentId)
     {
         var activity = ActivitySource.StartActivity("otopcua.deploy.apply", ActivityKind.Internal);
@@ -77,6 +78,7 @@ public static class OtOpcUaTelemetry
     }
 
     /// <summary>Span wrapping a full OPC UA address-space rebuild (Phase7 plan → apply).</summary>
+    /// <returns>The started <see cref="Activity"/>, or null when no listener is attached.</returns>
     public static Activity? StartAddressSpaceRebuildSpan()
         => ActivitySource.StartActivity("otopcua.opcua.address_space_rebuild", ActivityKind.Internal);
 }

src/Core/ZB.MOM.WW.OtOpcUa.Commons/OpcUa/DeferredAddressSpaceSink.cs

@@ -22,37 +22,22 @@ public sealed class DeferredAddressSpaceSink : IOpcUaAddressSpaceSink
     public void SetSink(IOpcUaAddressSpaceSink? sink) =>
         _inner = sink ?? NullOpcUaAddressSpaceSink.Instance;
 
-    /// <summary>Writes a value to the OPC UA address space through the inner sink.</summary>
+    /// <inheritdoc />
-    /// <param name="nodeId">The node ID of the variable.</param>
-    /// <param name="value">The value to write.</param>
-    /// <param name="quality">The OPC UA quality value.</param>
-    /// <param name="sourceTimestampUtc">The source timestamp in UTC.</param>
     public void WriteValue(string nodeId, object? value, OpcUaQuality quality, DateTime sourceTimestampUtc)
         => _inner.WriteValue(nodeId, value, quality, sourceTimestampUtc);
 
-    /// <summary>Writes an alarm state through the inner sink.</summary>
+    /// <inheritdoc />
-    /// <param name="alarmNodeId">The node ID of the alarm condition.</param>
-    /// <param name="active">Whether the alarm is active.</param>
-    /// <param name="acknowledged">Whether the alarm has been acknowledged.</param>
-    /// <param name="sourceTimestampUtc">The source timestamp in UTC.</param>
     public void WriteAlarmState(string alarmNodeId, bool active, bool acknowledged, DateTime sourceTimestampUtc)
         => _inner.WriteAlarmState(alarmNodeId, active, acknowledged, sourceTimestampUtc);
 
-    /// <summary>Ensures a folder exists in the address space through the inner sink.</summary>
+    /// <inheritdoc />
-    /// <param name="folderNodeId">The node ID of the folder.</param>
-    /// <param name="parentNodeId">The node ID of the parent folder, or null for root.</param>
-    /// <param name="displayName">The display name of the folder.</param>
     public void EnsureFolder(string folderNodeId, string? parentNodeId, string displayName)
         => _inner.EnsureFolder(folderNodeId, parentNodeId, displayName);
 
-    /// <summary>Ensures a variable exists in the address space through the inner sink.</summary>
+    /// <inheritdoc />
-    /// <param name="variableNodeId">The node ID of the variable.</param>
-    /// <param name="parentFolderNodeId">The node ID of the parent folder, or null for root.</param>
-    /// <param name="displayName">The display name of the variable.</param>
-    /// <param name="dataType">The OPC UA data type of the variable.</param>
     public void EnsureVariable(string variableNodeId, string? parentFolderNodeId, string displayName, string dataType)
         => _inner.EnsureVariable(variableNodeId, parentFolderNodeId, displayName, dataType);
 
-    /// <summary>Rebuilds the address space through the inner sink.</summary>
+    /// <inheritdoc />
     public void RebuildAddressSpace() => _inner.RebuildAddressSpace();
 }

src/Core/ZB.MOM.WW.OtOpcUa.Commons/OpcUa/DeferredServiceLevelPublisher.cs

@@ -16,7 +16,6 @@ public sealed class DeferredServiceLevelPublisher : IServiceLevelPublisher
     public void SetInner(IServiceLevelPublisher? inner) =>
         _inner = inner ?? NullServiceLevelPublisher.Instance;
 
-    /// <summary>Publishes a service level value to the inner publisher.</summary>
+    /// <inheritdoc />
-    /// <param name="serviceLevel">The service level to publish.</param>
     public void Publish(byte serviceLevel) => _inner.Publish(serviceLevel);
 }

src/Core/ZB.MOM.WW.OtOpcUa.Commons/Types/CorrelationId.cs

@@ -3,15 +3,18 @@ namespace ZB.MOM.WW.OtOpcUa.Commons.Types;
 public readonly record struct CorrelationId(Guid Value)
 {
     /// <summary>Creates a new CorrelationId with a randomly generated GUID.</summary>
+    /// <returns>A new <see cref="CorrelationId"/> backed by a random GUID.</returns>
     public static CorrelationId NewId() => new(Guid.NewGuid());
     /// <inheritdoc />
     public override string ToString() => Value.ToString("N");
     /// <summary>Parses a lowercase hex string without hyphens into a CorrelationId.</summary>
     /// <param name="s">The string to parse.</param>
+    /// <returns>A <see cref="CorrelationId"/> parsed from the supplied string.</returns>
     public static CorrelationId Parse(string s) => new(Guid.ParseExact(s, "N"));
     /// <summary>Attempts to parse a lowercase hex string without hyphens into a CorrelationId.</summary>
     /// <param name="s">The string to parse, or null.</param>
     /// <param name="id">The resulting CorrelationId if parsing succeeds.</param>
+    /// <returns><see langword="true"/> if parsing succeeded; otherwise <see langword="false"/>.</returns>
     public static bool TryParse(string? s, out CorrelationId id)
     {
         if (Guid.TryParseExact(s, "N", out var g)) { id = new CorrelationId(g); return true; }

src/Core/ZB.MOM.WW.OtOpcUa.Configuration/LocalCache/ILocalConfigCache.cs

@@ -21,10 +21,12 @@ public interface ILocalConfigCache
     /// <summary>Stores a generation snapshot in the local cache.</summary>
     /// <param name="snapshot">The generation snapshot to store.</param>
     /// <param name="ct">The cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task PutAsync(GenerationSnapshot snapshot, CancellationToken ct = default);
     /// <summary>Removes old generations, keeping only the most recent N.</summary>
     /// <param name="clusterId">The cluster identifier.</param>
     /// <param name="keepLatest">The number of latest generations to keep.</param>
     /// <param name="ct">The cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task PruneOldGenerationsAsync(string clusterId, int keepLatest = 10, CancellationToken ct = default);
 }

src/Core/ZB.MOM.WW.OtOpcUa.Configuration/LocalCache/LiteDbConfigCache.cs

@@ -45,9 +45,7 @@ public sealed class LiteDbConfigCache : ILocalConfigCache, IDisposable
         }
     }
 
-    /// <summary>Gets the most recent snapshot for the specified cluster.</summary>
+    /// <inheritdoc />
-    /// <param name="clusterId">The cluster ID.</param>
-    /// <param name="ct">Cancellation token.</param>
     public Task<GenerationSnapshot?> GetMostRecentAsync(string clusterId, CancellationToken ct = default)
     {
         ct.ThrowIfCancellationRequested();
@@ -58,9 +56,7 @@ public sealed class LiteDbConfigCache : ILocalConfigCache, IDisposable
         return Task.FromResult<GenerationSnapshot?>(snapshot);
     }
 
-    /// <summary>Stores a snapshot in the cache.</summary>
+    /// <inheritdoc />
-    /// <param name="snapshot">The snapshot to store.</param>
-    /// <param name="ct">Cancellation token.</param>
     public async Task PutAsync(GenerationSnapshot snapshot, CancellationToken ct = default)
     {
         ct.ThrowIfCancellationRequested();
@@ -89,10 +85,7 @@ public sealed class LiteDbConfigCache : ILocalConfigCache, IDisposable
         }
     }
 
-    /// <summary>Removes old generation snapshots, keeping only the latest ones.</summary>
+    /// <inheritdoc />
-    /// <param name="clusterId">The cluster ID.</param>
-    /// <param name="keepLatest">Number of latest generations to keep.</param>
-    /// <param name="ct">Cancellation token.</param>
     public Task PruneOldGenerationsAsync(string clusterId, int keepLatest = 10, CancellationToken ct = default)
     {
         ct.ThrowIfCancellationRequested();

src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Services/ILdapGroupRoleMappingService.cs

@@ -24,11 +24,13 @@ public interface ILdapGroupRoleMappingService
     /// </remarks>
     /// <param name="ldapGroups">The LDAP groups to search for.</param>
     /// <param name="cancellationToken">The cancellation token.</param>
+    /// <returns>A task resolving to the list of mappings whose LDAP group matches any of the provided groups.</returns>
     Task<IReadOnlyList<LdapGroupRoleMapping>> GetByGroupsAsync(
         IEnumerable<string> ldapGroups, CancellationToken cancellationToken);
 
     /// <summary>Enumerate every mapping; Admin UI listing only.</summary>
     /// <param name="cancellationToken">The cancellation token.</param>
+    /// <returns>A task resolving to all LDAP group role mappings.</returns>
     Task<IReadOnlyList<LdapGroupRoleMapping>> ListAllAsync(CancellationToken cancellationToken);
 
     /// <summary>Create a new grant.</summary>
@@ -39,11 +41,13 @@ public interface ILdapGroupRoleMappingService
     /// </exception>
     /// <param name="row">The LDAP group role mapping to create.</param>
     /// <param name="cancellationToken">The cancellation token.</param>
+    /// <returns>A task resolving to the newly created <see cref="LdapGroupRoleMapping"/> with any DB-assigned values populated.</returns>
     Task<LdapGroupRoleMapping> CreateAsync(LdapGroupRoleMapping row, CancellationToken cancellationToken);
 
     /// <summary>Delete a mapping by its surrogate key.</summary>
     /// <param name="id">The unique identifier of the mapping to delete.</param>
     /// <param name="cancellationToken">The cancellation token.</param>
+    /// <returns>A task that represents the asynchronous delete operation.</returns>
     Task DeleteAsync(Guid id, CancellationToken cancellationToken);
 }
 

src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Services/LdapGroupRoleMappingService.cs

@@ -10,10 +10,7 @@ namespace ZB.MOM.WW.OtOpcUa.Configuration.Services;
 /// </summary>
 public sealed class LdapGroupRoleMappingService(OtOpcUaConfigDbContext db) : ILdapGroupRoleMappingService
 {
-    /// <summary>Gets LDAP group role mappings for the specified groups.</summary>
+    /// <inheritdoc />
-    /// <param name="ldapGroups">The LDAP group names to query.</param>
-    /// <param name="cancellationToken">The cancellation token.</param>
-    /// <returns>The matching role mappings.</returns>
     public async Task<IReadOnlyList<LdapGroupRoleMapping>> GetByGroupsAsync(
         IEnumerable<string> ldapGroups, CancellationToken cancellationToken)
     {

src/Core/ZB.MOM.WW.OtOpcUa.Configuration/Validation/DraftValidator.cs

@@ -21,6 +21,7 @@ public static class DraftValidator
     ///     Validates a draft snapshot and returns all validation errors found in a single pass.
     /// </summary>
     /// <param name="draft">The draft snapshot to validate.</param>
+    /// <returns>A read-only list of all validation errors found; empty if the draft is valid.</returns>
     public static IReadOnlyList<ValidationError> Validate(DraftSnapshot draft)
     {
         var errors = new List<ValidationError>();
@@ -147,6 +148,7 @@ public static class DraftValidator
 
     /// <summary>Decision #125: EquipmentId = 'EQ-' + lowercase first 12 hex chars of the UUID.</summary>
     /// <param name="uuid">The equipment UUID to derive the ID from.</param>
+    /// <returns>The derived equipment ID string in the form <c>EQ-xxxxxxxxxxxx</c>.</returns>
     public static string DeriveEquipmentId(Guid uuid) =>
         "EQ-" + uuid.ToString("N")[..12].ToLowerInvariant();
 
@@ -203,6 +205,7 @@ public static class DraftValidator
     /// </remarks>
     /// <param name="cluster">The server cluster to validate.</param>
     /// <param name="clusterNodes">The cluster nodes to validate against the cluster configuration.</param>
+    /// <returns>A read-only list of all validation errors found; empty if the topology is valid.</returns>
     public static IReadOnlyList<ValidationError> ValidateClusterTopology(
         ServerCluster cluster,
         IReadOnlyList<ClusterNode> clusterNodes)

src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/DriverTypeRegistry.cs

@@ -55,6 +55,7 @@ public sealed class DriverTypeRegistry
 
     /// <summary>Look up a driver type by name. Throws if unknown.</summary>
     /// <param name="driverType">The driver type name to look up.</param>
+    /// <returns>The <see cref="DriverTypeMetadata"/> registered for the specified type name.</returns>
     public DriverTypeMetadata Get(string driverType)
     {
         ArgumentException.ThrowIfNullOrWhiteSpace(driverType);
@@ -69,6 +70,7 @@ public sealed class DriverTypeRegistry
 
     /// <summary>Try to look up a driver type by name. Returns null if unknown (no exception).</summary>
     /// <param name="driverType">The driver type name to look up.</param>
+    /// <returns>The matching <see cref="DriverTypeMetadata"/>, or <c>null</c> if not registered.</returns>
     public DriverTypeMetadata? TryGet(string driverType)
     {
         ArgumentException.ThrowIfNullOrWhiteSpace(driverType);
@@ -76,6 +78,7 @@ public sealed class DriverTypeRegistry
     }
 
     /// <summary>Snapshot of all registered driver types.</summary>
+    /// <returns>A read-only collection of all currently registered driver type metadata entries.</returns>
     public IReadOnlyCollection<DriverTypeMetadata> All() => _types.Values.ToList();
 }
 

src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/Historian/IHistorianDataSource.cs

@@ -28,6 +28,7 @@ public interface IHistorianDataSource : IDisposable
     /// <param name="endUtc">The end of the time range in UTC.</param>
     /// <param name="maxValuesPerNode">The maximum number of values to return per node.</param>
     /// <param name="cancellationToken">A cancellation token that can be used to cancel the operation.</param>
+    /// <returns>A task resolving to a <see cref="HistoryReadResult"/> containing the raw samples.</returns>
     Task<HistoryReadResult> ReadRawAsync(
         string fullReference,
         DateTime startUtc,
@@ -46,6 +47,7 @@ public interface IHistorianDataSource : IDisposable
     /// <param name="interval">The interval for bucketing samples.</param>
     /// <param name="aggregate">The aggregation function to apply to each bucket.</param>
     /// <param name="cancellationToken">A cancellation token that can be used to cancel the operation.</param>
+    /// <returns>A task resolving to a <see cref="HistoryReadResult"/> containing the processed interval samples.</returns>
     Task<HistoryReadResult> ReadProcessedAsync(
         string fullReference,
         DateTime startUtc,
@@ -63,6 +65,7 @@ public interface IHistorianDataSource : IDisposable
     /// <param name="fullReference">The full reference of the tag to read.</param>
     /// <param name="timestampsUtc">The list of timestamps to read values at.</param>
     /// <param name="cancellationToken">A cancellation token that can be used to cancel the operation.</param>
+    /// <returns>A task resolving to a <see cref="HistoryReadResult"/> with one sample per requested timestamp.</returns>
     Task<HistoryReadResult> ReadAtTimeAsync(
         string fullReference,
         IReadOnlyList<DateTime> timestampsUtc,
@@ -93,6 +96,7 @@ public interface IHistorianDataSource : IDisposable
     /// <param name="endUtc">The end of the time range in UTC.</param>
     /// <param name="maxEvents">The maximum number of events to return, or a non-positive value to use the default backend cap.</param>
     /// <param name="cancellationToken">A cancellation token that can be used to cancel the operation.</param>
+    /// <returns>A task resolving to a <see cref="HistoricalEventsResult"/> containing historical alarm and event records.</returns>
     Task<HistoricalEventsResult> ReadEventsAsync(
         string? sourceName,
         DateTime startUtc,
@@ -104,5 +108,6 @@ public interface IHistorianDataSource : IDisposable
     ///     Point-in-time health snapshot for diagnostics and dashboards. Pure
     ///     observation; never blocks on backend I/O.
     /// </summary>
+    /// <returns>The current <see cref="HistorianHealthSnapshot"/> for this data source.</returns>
     HistorianHealthSnapshot GetHealthSnapshot();
 }

src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/IAddressSpaceBuilder.cs

@@ -18,6 +18,7 @@ public interface IAddressSpaceBuilder
     /// </summary>
     /// <param name="browseName">OPC UA browse name (the segment of the path under the parent).</param>
     /// <param name="displayName">Human-readable display name. May equal <paramref name="browseName"/>.</param>
+    /// <returns>A child builder scoped to inside this folder.</returns>
     IAddressSpaceBuilder Folder(string browseName, string displayName);
 
     /// <summary>
@@ -27,6 +28,7 @@ public interface IAddressSpaceBuilder
     /// <param name="browseName">OPC UA browse name (the segment of the path under the parent folder).</param>
     /// <param name="displayName">Human-readable display name. May equal <paramref name="browseName"/>.</param>
     /// <param name="attributeInfo">Driver-side metadata for the variable.</param>
+    /// <returns>An opaque handle for the registered variable.</returns>
     IVariableHandle Variable(string browseName, string displayName, DriverAttributeInfo attributeInfo);
 
     /// <summary>
@@ -56,6 +58,7 @@ public interface IVariableHandle
     ///     <c>Acknowledge</c>, <c>Deactivate</c>).
     /// </summary>
     /// <param name="info">The alarm condition information.</param>
+    /// <returns>A sink that receives alarm lifecycle transitions for this condition.</returns>
     IAlarmConditionSink MarkAsAlarmCondition(AlarmConditionInfo info);
 }
 

src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/IAlarmSource.cs

@@ -13,6 +13,7 @@ public interface IAlarmSource
     /// </summary>
     /// <param name="sourceNodeIds">The driver node IDs to subscribe to.</param>
     /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>A task that resolves to an opaque <see cref="IAlarmSubscriptionHandle"/> for the new subscription.</returns>
     Task<IAlarmSubscriptionHandle> SubscribeAlarmsAsync(
         IReadOnlyList<string> sourceNodeIds,
         CancellationToken cancellationToken);
@@ -20,11 +21,13 @@ public interface IAlarmSource
     /// <summary>Cancel an alarm subscription returned by <see cref="SubscribeAlarmsAsync"/>.</summary>
     /// <param name="handle">The subscription handle returned from <see cref="SubscribeAlarmsAsync"/>.</param>
     /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task UnsubscribeAlarmsAsync(IAlarmSubscriptionHandle handle, CancellationToken cancellationToken);
 
     /// <summary>Acknowledge one or more active alarms by source node ID + condition ID.</summary>
     /// <param name="acknowledgements">The batch of alarm acknowledgement requests.</param>
     /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task AcknowledgeAsync(
         IReadOnlyList<AlarmAcknowledgeRequest> acknowledgements,
         CancellationToken cancellationToken);

src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/IDriver.cs

@@ -23,6 +23,7 @@ public interface IDriver
     /// <summary>Initialize the driver from its <c>DriverConfig</c> JSON; open connections; prepare for first use.</summary>
     /// <param name="driverConfigJson">The driver configuration as JSON.</param>
     /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task InitializeAsync(string driverConfigJson, CancellationToken cancellationToken);
 
     /// <summary>
@@ -37,13 +38,16 @@ public interface IDriver
     /// </remarks>
     /// <param name="driverConfigJson">The driver configuration as JSON.</param>
     /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task ReinitializeAsync(string driverConfigJson, CancellationToken cancellationToken);
 
     /// <summary>Stop the driver, close connections, release resources. Called on shutdown or driver removal.</summary>
     /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task ShutdownAsync(CancellationToken cancellationToken);
 
     /// <summary>Current health snapshot, polled by Core for the status dashboard and ServiceLevel.</summary>
+    /// <returns>The current driver health snapshot.</returns>
     DriverHealth GetHealth();
 
     /// <summary>
@@ -56,6 +60,7 @@ public interface IDriver
     ///     allocation tracking". Tier C drivers (process-isolated) report through the same
     ///     interface but the cache-flush is internal to their host.
     /// </remarks>
+    /// <returns>The approximate driver-attributable memory footprint in bytes.</returns>
     long GetMemoryFootprint();
 
     /// <summary>
@@ -63,5 +68,6 @@ public interface IDriver
     ///     Required-for-correctness state must NOT be flushed.
     /// </summary>
     /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task FlushOptionalCachesAsync(CancellationToken cancellationToken);
 }

src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/IDriverFactory.cs

@@ -34,12 +34,8 @@ public sealed class NullDriverFactory : IDriverFactory
     public static readonly NullDriverFactory Instance = new();
     private NullDriverFactory() { }
 
-    /// <summary>Creates a driver (always returns null in this null implementation).</summary>
+    /// <inheritdoc />
-    /// <param name="driverType">The driver type name.</param>
-    /// <param name="driverInstanceId">The driver instance identifier.</param>
-    /// <param name="driverConfigJson">The driver configuration as a JSON string.</param>
-    /// <returns>Always returns null.</returns>
     public IDriver? TryCreate(string driverType, string driverInstanceId, string driverConfigJson) => null;
-    /// <summary>Gets the collection of supported driver types (empty in this null implementation).</summary>
+    /// <inheritdoc />
     public IReadOnlyCollection<string> SupportedTypes { get; } = Array.Empty<string>();
 }

src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/IDriverHealthPublisher.cs

@@ -11,6 +11,10 @@ public interface IDriverHealthPublisher
     ///     Publishes a health snapshot for one driver instance. Implementations must be
     ///     non-blocking and tolerant of being called from any thread.
     /// </summary>
+    /// <param name="clusterId">The cluster identifier the driver instance belongs to.</param>
+    /// <param name="driverInstanceId">The unique identifier of the driver instance.</param>
+    /// <param name="health">The current health state of the driver instance.</param>
+    /// <param name="errorCount5Min">Number of errors recorded in the past 5 minutes.</param>
     void Publish(
         string clusterId,
         string driverInstanceId,

src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/IDriverProbe.cs

@@ -17,6 +17,10 @@ public interface IDriverProbe
     ///     timeout cancellation. Never throw on connection failure; instead return a result
     ///     with <c>Ok = false</c> + a message.
     /// </summary>
+    /// <param name="configJson">Driver configuration JSON; same shape the runtime driver consumes.</param>
+    /// <param name="timeout">Maximum duration for the probe attempt.</param>
+    /// <param name="ct">Cancellation token for the probe operation.</param>
+    /// <returns>A task containing the probe result with success status and optional latency.</returns>
     Task<DriverProbeResult> ProbeAsync(string configJson, TimeSpan timeout, CancellationToken ct);
 }
 

src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/IDriverSupervisor.cs

@@ -22,5 +22,6 @@ public interface IDriverSupervisor
     /// </summary>
     /// <param name="reason">Human-readable reason — flows into the supervisor's logs.</param>
     /// <param name="cancellationToken">Cancels the recycle request; an in-flight restart is not interrupted.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task RecycleAsync(string reason, CancellationToken cancellationToken);
 }

src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/IHistoryProvider.cs

@@ -94,6 +94,7 @@ public interface IHistoryProvider
     ///     <c>HistorianDataSource</c>). The asymmetry is intentional — Core.Abstractions-006.
     /// </param>
     /// <param name="cancellationToken">Request cancellation.</param>
+    /// <returns>A task that resolves to the historical events result for the requested window.</returns>
     /// <remarks>
     ///     Default implementation throws. Only drivers with an event historian (Galaxy via the
     ///     Wonderware Alarm &amp; Events log) override. Modbus / the OPC UA Client driver stay

src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/IHostConnectivityProbe.cs

@@ -16,6 +16,7 @@ public interface IHostConnectivityProbe
     ///     Snapshot of host-level connectivity. The Core uses this to drive Bad-quality
     ///     fan-out scoped to the affected host's subtree (not the whole driver namespace).
     /// </summary>
+    /// <returns>A snapshot list of per-host connectivity statuses.</returns>
     IReadOnlyList<HostConnectivityStatus> GetHostStatuses();
 
     /// <summary>Fired when a host transitions Running ↔ Stopped (or similar lifecycle change).</summary>

src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/ITagDiscovery.cs

@@ -13,5 +13,6 @@ public interface ITagDiscovery
     /// </summary>
     /// <param name="builder">The address space builder to stream discovered nodes into.</param>
     /// <param name="cancellationToken">A cancellation token for the discovery operation.</param>
+    /// <returns>A task that represents the asynchronous discovery operation.</returns>
     Task DiscoverAsync(IAddressSpaceBuilder builder, CancellationToken cancellationToken);
 }

src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/IWritable.cs

@@ -19,6 +19,7 @@ public interface IWritable
     /// </summary>
     /// <param name="writes">Pairs of full reference + value to write.</param>
     /// <param name="cancellationToken">Cancellation token; the driver should abort the batch if cancelled.</param>
+    /// <returns>A task that resolves to one <see cref="WriteResult"/> per requested write, in the same order.</returns>
     Task<IReadOnlyList<WriteResult>> WriteAsync(
         IReadOnlyList<WriteRequest> writes,
         CancellationToken cancellationToken);

src/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions/PollGroupEngine.cs

@@ -41,6 +41,7 @@ public sealed class PollGroupEngine : IAsyncDisposable
     /// <summary>Default floor for publishing intervals — matches the Modbus 100 ms cap.</summary>
     public static readonly TimeSpan DefaultMinInterval = TimeSpan.FromMilliseconds(100);
 
+    /// <summary>Initializes a new poll-group engine with the supplied reader, change callback, interval floor, and optional error sink.</summary>
     /// <param name="reader">Driver-supplied batch reader; snapshots MUST be returned in the same
     ///     order as the input references.</param>
     /// <param name="onChange">Callback invoked per changed tag — the driver forwards to its own
@@ -68,6 +69,7 @@ public sealed class PollGroupEngine : IAsyncDisposable
     /// <summary>Register a new polled subscription and start its background loop.</summary>
     /// <param name="fullReferences">The list of tag references to poll.</param>
     /// <param name="publishingInterval">The desired polling interval; will be clamped to the configured minimum.</param>
+    /// <returns>A subscription handle that can be passed to <see cref="Unsubscribe"/> to cancel the loop.</returns>
     public ISubscriptionHandle Subscribe(IReadOnlyList<string> fullReferences, TimeSpan publishingInterval)
     {
         ArgumentNullException.ThrowIfNull(fullReferences);
@@ -207,6 +209,7 @@ public sealed class PollGroupEngine : IAsyncDisposable
     }
 
     /// <summary>Cancel every active subscription and await all loop tasks. Idempotent.</summary>
+    /// <returns>A value task that represents the asynchronous dispose operation.</returns>
     public async ValueTask DisposeAsync()
     {
         // Cancel all loops first so they can all start winding down in parallel.
@@ -253,7 +256,7 @@ public sealed class PollGroupEngine : IAsyncDisposable
 
     private sealed record PollSubscriptionHandle(long Id) : ISubscriptionHandle
     {
-        /// <summary>Gets a diagnostic identifier for this subscription.</summary>
+        /// <inheritdoc />
         public string DiagnosticId => $"poll-sub-{Id}";
     }
 }

src/Core/ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian/IAlarmHistorianSink.cs

@@ -26,9 +26,11 @@ public interface IAlarmHistorianSink
     /// <summary>Durably enqueue the event. Returns as soon as the queue row is committed.</summary>
     /// <param name="evt">The alarm historian event to enqueue.</param>
     /// <param name="cancellationToken">A cancellation token for async operations.</param>
+    /// <returns>A task that represents the asynchronous enqueue operation.</returns>
     Task EnqueueAsync(AlarmHistorianEvent evt, CancellationToken cancellationToken);
 
     /// <summary>Snapshot of current queue depth + drain health.</summary>
+    /// <returns>A snapshot of the current queue depth and drain state.</returns>
     HistorianSinkStatus GetStatus();
 }
 
@@ -97,6 +99,7 @@ public interface IAlarmHistorianWriter
     /// <summary>Push a batch of events to the historian. Returns one outcome per event, same order.</summary>
     /// <param name="batch">The batch of alarm historian events to write.</param>
     /// <param name="cancellationToken">A cancellation token for async operations.</param>
+    /// <returns>A task that resolves to one write outcome per event, in the same order as the batch.</returns>
     Task<IReadOnlyList<HistorianWriteOutcome>> WriteBatchAsync(
         IReadOnlyList<AlarmHistorianEvent> batch, CancellationToken cancellationToken);
 }

src/Core/ZB.MOM.WW.OtOpcUa.Core.AlarmHistorian/SqliteStoreAndForwardSink.cs

@@ -255,6 +255,7 @@ public sealed class SqliteStoreAndForwardSink : IAlarmHistorianSink, IDisposable
     /// </remarks>
     /// <param name="evt">The alarm historian event to enqueue.</param>
     /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public async Task EnqueueAsync(AlarmHistorianEvent evt, CancellationToken cancellationToken)
     {
         if (evt is null) throw new ArgumentNullException(nameof(evt));
@@ -345,6 +346,7 @@ public sealed class SqliteStoreAndForwardSink : IAlarmHistorianSink, IDisposable
     ///     connections per tick, each paying the open + PRAGMA cost.
     /// </remarks>
     /// <param name="ct">Cancellation token for the operation.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public async Task DrainOnceAsync(CancellationToken ct)
     {
         if (_disposed) return;
@@ -490,7 +492,7 @@ public sealed class SqliteStoreAndForwardSink : IAlarmHistorianSink, IDisposable
         }
     }
 
-    /// <summary>Gets the current status of the historian sink including queue depth and drain state.</summary>
+    /// <inheritdoc />
     public HistorianSinkStatus GetStatus()
     {
         // Core.AlarmHistorian-008: read the non-dead-lettered count from the in-memory
@@ -534,6 +536,7 @@ public sealed class SqliteStoreAndForwardSink : IAlarmHistorianSink, IDisposable
     }
 
     /// <summary>Operator action from Admin UI — retry every dead-lettered row. Non-cascading: they rejoin the regular queue + get a fresh backoff.</summary>
+    /// <returns>The number of rows moved back to the active queue.</returns>
     public int RetryDeadLettered()
     {
         using var conn = OpenConnection();

src/Core/ZB.MOM.WW.OtOpcUa.Core.ScriptedAlarms/ScriptedAlarmEngine.cs

@@ -97,6 +97,7 @@ public sealed class ScriptedAlarmEngine : IDisposable
     ///     copy under the gate. (Core.ScriptedAlarms-013.)
     /// </remarks>
     /// <param name="alarmId">The alarm identifier to look up.</param>
+    /// <returns>The live read-cache dictionary for the alarm, or <see langword="null"/> if not yet allocated.</returns>
     internal IReadOnlyDictionary<string, DataValueSnapshot>? TryGetScratchReadCacheForTest(string alarmId)
         => _scratchByAlarmId.TryGetValue(alarmId, out var s) ? s.ReadCache : null;
 
@@ -113,6 +114,7 @@ public sealed class ScriptedAlarmEngine : IDisposable
     ///     (Core.ScriptedAlarms-013.)
     /// </remarks>
     /// <param name="alarmId">The alarm identifier to look up.</param>
+    /// <returns>The reusable <see cref="AlarmPredicateContext"/> for the alarm, or <see langword="null"/> if not yet allocated.</returns>
     internal AlarmPredicateContext? TryGetScratchContextForTest(string alarmId)
         => _scratchByAlarmId.TryGetValue(alarmId, out var s) ? s.Context : null;
     private readonly ConcurrentDictionary<string, DataValueSnapshot> _valueCache
@@ -175,6 +177,7 @@ public sealed class ScriptedAlarmEngine : IDisposable
     /// </summary>
     /// <param name="definitions">The alarm definitions to load.</param>
     /// <param name="ct">The cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public async Task LoadAsync(IReadOnlyList<ScriptedAlarmDefinition> definitions, CancellationToken ct)
     {
         if (_disposed) throw new ObjectDisposedException(nameof(ScriptedAlarmEngine));
@@ -306,10 +309,12 @@ public sealed class ScriptedAlarmEngine : IDisposable
     ///     unknown alarm. Mainly used for diagnostics + the Admin UI status page.
     /// </summary>
     /// <param name="alarmId">The alarm identifier.</param>
+    /// <returns>The current <see cref="AlarmConditionState"/> for the alarm, or <see langword="null"/> if the alarm is unknown.</returns>
     public AlarmConditionState? GetState(string alarmId)
         => _alarms.TryGetValue(alarmId, out var s) ? s.Condition : null;
 
     /// <summary>Gets the current persisted state for all loaded alarms.</summary>
+    /// <returns>A snapshot collection of all current alarm condition states.</returns>
     public IReadOnlyCollection<AlarmConditionState> GetAllStates()
         => _alarms.Values.Select(a => a.Condition).ToArray();
 
@@ -318,6 +323,7 @@ public sealed class ScriptedAlarmEngine : IDisposable
     /// <param name="user">The user performing the acknowledgment.</param>
     /// <param name="comment">An optional comment to attach to the acknowledgment.</param>
     /// <param name="ct">The cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public Task AcknowledgeAsync(string alarmId, string user, string? comment, CancellationToken ct)
         => ApplyAsync(alarmId, ct, cur => Part9StateMachine.ApplyAcknowledge(cur, user, comment, _clock()));
 
@@ -326,6 +332,7 @@ public sealed class ScriptedAlarmEngine : IDisposable
     /// <param name="user">The user performing the confirmation.</param>
     /// <param name="comment">An optional comment to attach to the confirmation.</param>
     /// <param name="ct">The cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public Task ConfirmAsync(string alarmId, string user, string? comment, CancellationToken ct)
         => ApplyAsync(alarmId, ct, cur => Part9StateMachine.ApplyConfirm(cur, user, comment, _clock()));
 
@@ -333,6 +340,7 @@ public sealed class ScriptedAlarmEngine : IDisposable
     /// <param name="alarmId">The alarm identifier.</param>
     /// <param name="user">The user performing the shelve operation.</param>
     /// <param name="ct">The cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public Task OneShotShelveAsync(string alarmId, string user, CancellationToken ct)
         => ApplyAsync(alarmId, ct, cur => Part9StateMachine.ApplyOneShotShelve(cur, user, _clock()));
 
@@ -341,6 +349,7 @@ public sealed class ScriptedAlarmEngine : IDisposable
     /// <param name="user">The user performing the shelve operation.</param>
     /// <param name="unshelveAtUtc">The UTC time at which the shelve will automatically expire.</param>
     /// <param name="ct">The cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public Task TimedShelveAsync(string alarmId, string user, DateTime unshelveAtUtc, CancellationToken ct)
         => ApplyAsync(alarmId, ct, cur => Part9StateMachine.ApplyTimedShelve(cur, user, unshelveAtUtc, _clock()));
 
@@ -348,6 +357,7 @@ public sealed class ScriptedAlarmEngine : IDisposable
     /// <param name="alarmId">The alarm identifier.</param>
     /// <param name="user">The user performing the unshelve operation.</param>
     /// <param name="ct">The cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public Task UnshelveAsync(string alarmId, string user, CancellationToken ct)
         => ApplyAsync(alarmId, ct, cur => Part9StateMachine.ApplyUnshelve(cur, user, _clock()));
 
@@ -355,6 +365,7 @@ public sealed class ScriptedAlarmEngine : IDisposable
     /// <param name="alarmId">The alarm identifier.</param>
     /// <param name="user">The user performing the enable operation.</param>
     /// <param name="ct">The cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public Task EnableAsync(string alarmId, string user, CancellationToken ct)
         => ApplyAsync(alarmId, ct, cur => Part9StateMachine.ApplyEnable(cur, user, _clock()));
 
@@ -362,6 +373,7 @@ public sealed class ScriptedAlarmEngine : IDisposable
     /// <param name="alarmId">The alarm identifier.</param>
     /// <param name="user">The user performing the disable operation.</param>
     /// <param name="ct">The cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public Task DisableAsync(string alarmId, string user, CancellationToken ct)
         => ApplyAsync(alarmId, ct, cur => Part9StateMachine.ApplyDisable(cur, user, _clock()));
 
@@ -370,6 +382,7 @@ public sealed class ScriptedAlarmEngine : IDisposable
     /// <param name="user">The user adding the comment.</param>
     /// <param name="text">The comment text.</param>
     /// <param name="ct">The cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public Task AddCommentAsync(string alarmId, string user, string text, CancellationToken ct)
         => ApplyAsync(alarmId, ct, cur => Part9StateMachine.ApplyAddComment(cur, user, text, _clock()));
 

src/Core/ZB.MOM.WW.OtOpcUa.Core.Scripting/DependencyExtractor.cs

@@ -39,6 +39,7 @@ public static class DependencyExtractor
     ///     paths, or a list of rejection messages if non-literal paths were used.
     /// </summary>
     /// <param name="scriptSource">The script source code to analyze.</param>
+    /// <returns>The extracted dependency paths, or rejection messages for unsupported patterns.</returns>
     public static DependencyExtractionResult Extract(string scriptSource)
     {
         if (string.IsNullOrWhiteSpace(scriptSource))

src/Core/ZB.MOM.WW.OtOpcUa.Core.Scripting/ScriptContext.cs

@@ -41,6 +41,7 @@ public abstract class ScriptContext
     ///     right upstream tags at load time.
     /// </remarks>
     /// <param name="path">The literal tag path to read.</param>
+    /// <returns>The current <see cref="DataValueSnapshot"/> for the tag, including value, quality, and timestamp.</returns>
     public abstract DataValueSnapshot GetTag(string path);
 
     /// <summary>
@@ -81,6 +82,7 @@ public abstract class ScriptContext
     /// <param name="current">The current value to check.</param>
     /// <param name="previous">The previous value to compare against.</param>
     /// <param name="tolerance">The minimum difference threshold for a change to be detected.</param>
+    /// <returns><see langword="true"/> when the absolute difference between current and previous exceeds tolerance.</returns>
     public static bool Deadband(double current, double previous, double tolerance)
         => Math.Abs(current - previous) > tolerance;
 }

src/Core/ZB.MOM.WW.OtOpcUa.Core.Scripting/ScriptEvaluator.cs

@@ -66,6 +66,7 @@ public sealed class ScriptEvaluator<TContext, TResult> : IDisposable
 
     /// <summary>Compiles user script source into an evaluator.</summary>
     /// <param name="scriptSource">The user script source code to compile.</param>
+    /// <returns>A compiled <see cref="ScriptEvaluator{TContext, TResult}"/> ready to invoke.</returns>
     public static ScriptEvaluator<TContext, TResult> Compile(string scriptSource)
     {
         if (scriptSource is null) throw new ArgumentNullException(nameof(scriptSource));
@@ -173,6 +174,7 @@ public sealed class ScriptEvaluator<TContext, TResult> : IDisposable
     /// <summary>Runs the script against an already-constructed context.</summary>
     /// <param name="context">The script context.</param>
     /// <param name="ct">Cancellation token for the operation.</param>
+    /// <returns>A task that resolves to the script's return value.</returns>
     public Task<TResult> RunAsync(TContext context, CancellationToken ct = default)
     {
         if (_disposed) throw new ObjectDisposedException(nameof(ScriptEvaluator<TContext, TResult>));

src/Core/ZB.MOM.WW.OtOpcUa.Core.Scripting/ScriptSandbox.cs

@@ -43,6 +43,7 @@ public static class ScriptSandbox
     ///     to resolve <c>ctx.GetTag(...)</c> calls.
     /// </summary>
     /// <param name="contextType">The concrete script context type to use for compilation.</param>
+    /// <returns>The sandbox configuration for compiling scripts with the given context type.</returns>
     public static SandboxConfig Build(Type contextType)
     {
         if (contextType is null) throw new ArgumentNullException(nameof(contextType));

src/Core/ZB.MOM.WW.OtOpcUa.Core.VirtualTags/DependencyGraph.cs

@@ -156,6 +156,7 @@ public sealed class DependencyGraph
     ///     dependencies. Throws <see cref="DependencyCycleException"/> if any cycle
     ///     exists. Implemented via Kahn's algorithm.
     /// </summary>
+    /// <returns>A list of node IDs in topological evaluation order.</returns>
     public IReadOnlyList<string> TopologicalSort()
     {
         // Kahn's framing: edge u -> v means "u must come before v". For dependencies,
@@ -205,6 +206,7 @@ public sealed class DependencyGraph
     ///     Empty list means the graph is a DAG. Useful for surfacing every cycle in one
     ///     rejection pass so operators see all of them, not just one at a time.
     /// </summary>
+    /// <returns>A list of strongly-connected components that form cycles; empty if the graph is acyclic.</returns>
     public IReadOnlyList<IReadOnlyList<string>> DetectCycles()
     {
         // Iterative Tarjan's SCC. Avoids recursion so deep graphs don't StackOverflow.

src/Core/ZB.MOM.WW.OtOpcUa.Core.VirtualTags/ITagUpstreamSource.cs

@@ -30,6 +30,7 @@ public interface ITagUpstreamSource
     ///     when the path isn't configured.
     /// </summary>
     /// <param name="path">The tag path to read.</param>
+    /// <returns>The last-known value and quality snapshot for the tag.</returns>
     DataValueSnapshot ReadTag(string path);
 
     /// <summary>
@@ -40,5 +41,6 @@ public interface ITagUpstreamSource
     /// </summary>
     /// <param name="path">The tag path to subscribe to.</param>
     /// <param name="observer">The callback to invoke when the value changes.</param>
+    /// <returns>An <see cref="IDisposable"/> that cancels the subscription when disposed.</returns>
     IDisposable SubscribeTag(string path, Action<string, DataValueSnapshot> observer);
 }

src/Core/ZB.MOM.WW.OtOpcUa.Core.VirtualTags/VirtualTagEngine.cs

@@ -198,6 +198,7 @@ public sealed class VirtualTagEngine : IDisposable
     ///     default. Also called after a config reload.
     /// </summary>
     /// <param name="ct">Cancellation token to stop evaluation.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public async Task EvaluateAllAsync(CancellationToken ct = default)
     {
         EnsureLoaded();
@@ -212,6 +213,7 @@ public sealed class VirtualTagEngine : IDisposable
     /// <summary>Evaluate a single tag — used by the timer trigger + test hooks.</summary>
     /// <param name="path">Path of the virtual tag to evaluate.</param>
     /// <param name="ct">Cancellation token to stop evaluation.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public Task EvaluateOneAsync(string path, CancellationToken ct = default)
     {
         EnsureLoaded();
@@ -226,6 +228,7 @@ public sealed class VirtualTagEngine : IDisposable
     ///     evaluation result.
     /// </summary>
     /// <param name="path">Path of the tag to read.</param>
+    /// <returns>The most recently cached value and quality for the tag path.</returns>
     public DataValueSnapshot Read(string path)
     {
         if (string.IsNullOrWhiteSpace(path))
@@ -242,6 +245,7 @@ public sealed class VirtualTagEngine : IDisposable
     /// </summary>
     /// <param name="path">Path of the tag to subscribe to.</param>
     /// <param name="observer">Callback invoked with the tag path and new value on each evaluation.</param>
+    /// <returns>An <see cref="IDisposable"/> that cancels the subscription when disposed.</returns>
     public IDisposable Subscribe(string path, Action<string, DataValueSnapshot> observer)
     {
         // Race-safe pattern paired with Unsub.Dispose: if Unsub.Dispose removed the

src/Core/ZB.MOM.WW.OtOpcUa.Core/Authorization/AuthorizationDecision.cs

@@ -19,6 +19,7 @@ public sealed record AuthorizationDecision(
     public bool IsAllowed => Verdict == AuthorizationVerdict.Allow;
 
     /// <summary>Convenience constructor for the common "no grants matched" outcome.</summary>
+    /// <returns>An <see cref="AuthorizationDecision"/> with <see cref="AuthorizationVerdict.NotGranted"/> and empty provenance.</returns>
     public static AuthorizationDecision NotGranted() => new(AuthorizationVerdict.NotGranted, []);
 
     /// <summary>Allow with the list of grants that matched.</summary>

src/Core/ZB.MOM.WW.OtOpcUa.Core/Authorization/IPermissionEvaluator.cs

@@ -22,5 +22,6 @@ public interface IPermissionEvaluator
     /// <param name="session">The user session containing resolved LDAP groups and roles.</param>
     /// <param name="operation">The OPC UA operation being requested.</param>
     /// <param name="scope">The node address scope being accessed.</param>
+    /// <returns>An <see cref="AuthorizationDecision"/> indicating whether the operation is allowed.</returns>
     AuthorizationDecision Authorize(UserAuthorizationState session, OpcUaOperation operation, NodeScope scope);
 }

src/Core/ZB.MOM.WW.OtOpcUa.Core/Authorization/PermissionTrie.cs

@@ -33,6 +33,7 @@ public sealed class PermissionTrie
     /// </summary>
     /// <param name="scope">The node scope to match permissions for.</param>
     /// <param name="ldapGroups">The user's LDAP group memberships.</param>
+    /// <returns>The list of grants that apply to the given scope for any of the session's LDAP groups.</returns>
     public IReadOnlyList<MatchedGrant> CollectMatches(NodeScope scope, IEnumerable<string> ldapGroups)
     {
         ArgumentNullException.ThrowIfNull(scope);

src/Core/ZB.MOM.WW.OtOpcUa.Core/Authorization/PermissionTrieBuilder.cs

@@ -41,6 +41,7 @@ public static class PermissionTrieBuilder
     ///     Core-011 production hazard. The callback fires only when <paramref name="scopePaths"/>
     ///     is non-null (a null lookup is the explicit deterministic-test fallback mode).
     /// </param>
+    /// <returns>An immutable <see cref="PermissionTrie"/> for the given cluster and generation.</returns>
     public static PermissionTrie Build(
         string clusterId,
         long generationId,

src/Core/ZB.MOM.WW.OtOpcUa.Core/Authorization/PermissionTrieCache.cs

@@ -34,6 +34,7 @@ public sealed class PermissionTrieCache
 
     /// <summary>Get the current-generation trie for a cluster; null when nothing installed.</summary>
     /// <param name="clusterId">The cluster identifier.</param>
+    /// <returns>The current-generation trie, or null if nothing is installed for the cluster.</returns>
     public PermissionTrie? GetTrie(string clusterId)
     {
         ArgumentException.ThrowIfNullOrWhiteSpace(clusterId);
@@ -43,6 +44,7 @@ public sealed class PermissionTrieCache
     /// <summary>Get a specific (cluster, generation) trie; null if that pair isn't cached.</summary>
     /// <param name="clusterId">The cluster identifier.</param>
     /// <param name="generationId">The generation identifier.</param>
+    /// <returns>The trie for the specified cluster and generation, or null if not cached.</returns>
     public PermissionTrie? GetTrie(string clusterId, long generationId)
     {
         if (!_byCluster.TryGetValue(clusterId, out var entry)) return null;
@@ -51,6 +53,7 @@ public sealed class PermissionTrieCache
 
     /// <summary>The generation id the <see cref="GetTrie(string)"/> shortcut currently serves for a cluster.</summary>
     /// <param name="clusterId">The cluster identifier.</param>
+    /// <returns>The current generation ID, or null if no trie is installed for the cluster.</returns>
     public long? CurrentGenerationId(string clusterId)
         => _byCluster.TryGetValue(clusterId, out var entry) ? entry.Current.GenerationId : null;
 
@@ -111,11 +114,13 @@ public sealed class PermissionTrieCache
 
         /// <summary>Creates a cluster entry from a single trie.</summary>
         /// <param name="trie">The permission trie to create the entry from.</param>
+        /// <returns>A new <see cref="ClusterEntry"/> containing the single trie as the current generation.</returns>
         public static ClusterEntry FromSingle(PermissionTrie trie) =>
             new(trie, new Dictionary<long, PermissionTrie> { [trie.GenerationId] = trie });
 
         /// <summary>Creates a new entry with an additional trie, updating current if it's newer.</summary>
         /// <param name="trie">The new permission trie to add.</param>
+        /// <returns>A new <see cref="ClusterEntry"/> with the trie added and the current pointer updated if the new generation is newer.</returns>
         public ClusterEntry WithAdditional(PermissionTrie trie)
         {
             var next = new Dictionary<long, PermissionTrie>(Tries) { [trie.GenerationId] = trie };

src/Core/ZB.MOM.WW.OtOpcUa.Core/Authorization/TriePermissionEvaluator.cs

@@ -24,11 +24,7 @@ public sealed class TriePermissionEvaluator : IPermissionEvaluator
         _timeProvider = timeProvider ?? TimeProvider.System;
     }
 
-    /// <summary>Authorizes an operation against the user's session and node scope.</summary>
+    /// <inheritdoc />
-    /// <param name="session">The user's authorization session.</param>
-    /// <param name="operation">The OPC UA operation to authorize.</param>
-    /// <param name="scope">The target node scope.</param>
-    /// <returns>An authorization decision indicating whether the operation is allowed.</returns>
     public AuthorizationDecision Authorize(UserAuthorizationState session, OpcUaOperation operation, NodeScope scope)
     {
         ArgumentNullException.ThrowIfNull(session);

src/Core/ZB.MOM.WW.OtOpcUa.Core/Authorization/UserAuthorizationState.cs

@@ -64,6 +64,7 @@ public sealed record UserAuthorizationState
     ///     whenever this is true.
     /// </summary>
     /// <param name="utcNow">The current UTC time.</param>
+    /// <returns><c>true</c> when the state exceeds its maximum staleness ceiling.</returns>
     public bool IsStale(DateTime utcNow) => utcNow - MembershipResolvedUtc > AuthCacheMaxStaleness;
 
     /// <summary>
@@ -72,6 +73,7 @@ public sealed record UserAuthorizationState
     ///     call still evaluates against the cached memberships.
     /// </summary>
     /// <param name="utcNow">The current UTC time.</param>
+    /// <returns><c>true</c> when a background refresh should be initiated but the current cached memberships are still usable.</returns>
     public bool NeedsRefresh(DateTime utcNow) =>
         !IsStale(utcNow) && utcNow - MembershipResolvedUtc > MembershipFreshnessInterval;
 }

src/Core/ZB.MOM.WW.OtOpcUa.Core/Hosting/DriverFactoryRegistry.cs

@@ -63,6 +63,7 @@ public sealed class DriverFactoryRegistry
     ///     missing-assembly deployment doesn't take down the whole server.
     /// </summary>
     /// <param name="driverType">The driver type to look up.</param>
+    /// <returns>The registered factory delegate, or <see langword="null"/> if no factory was registered for the type.</returns>
     public Func<string, string, IDriver>? TryGet(string driverType)
     {
         ArgumentException.ThrowIfNullOrWhiteSpace(driverType);
@@ -75,6 +76,7 @@ public sealed class DriverFactoryRegistry
     ///     case upstream; we don't double-surface that failure here.
     /// </summary>
     /// <param name="driverType">The driver type to look up.</param>
+    /// <returns>The registered <see cref="DriverTier"/>, or <see cref="DriverTier.A"/> if the type is unknown.</returns>
     public DriverTier GetTier(string driverType)
     {
         ArgumentException.ThrowIfNullOrWhiteSpace(driverType);

src/Core/ZB.MOM.WW.OtOpcUa.Core/Hosting/DriverFactoryRegistryAdapter.cs

@@ -20,16 +20,13 @@ public sealed class DriverFactoryRegistryAdapter : IDriverFactory
         _registry = registry;
     }
 
-    /// <summary>Attempts to create a driver instance by type and configuration.</summary>
+    /// <inheritdoc />
-    /// <param name="driverType">The driver type name.</param>
-    /// <param name="driverInstanceId">The driver instance identifier.</param>
-    /// <param name="driverConfigJson">The driver configuration as a JSON string.</param>
     public IDriver? TryCreate(string driverType, string driverInstanceId, string driverConfigJson)
     {
         var factory = _registry.TryGet(driverType);
         return factory?.Invoke(driverInstanceId, driverConfigJson);
     }
 
-    /// <summary>Gets the collection of supported driver type names.</summary>
+    /// <inheritdoc />
     public IReadOnlyCollection<string> SupportedTypes => _registry.RegisteredTypes;
 }

src/Core/ZB.MOM.WW.OtOpcUa.Core/Hosting/DriverHost.cs

@@ -21,6 +21,7 @@ public sealed class DriverHost : IAsyncDisposable
 
     /// <summary>Gets the health status of a registered driver.</summary>
     /// <param name="driverInstanceId">The driver instance identifier to query.</param>
+    /// <returns>The driver health if the driver is registered; otherwise null.</returns>
     public DriverHealth? GetHealth(string driverInstanceId)
     {
         lock (_lock)
@@ -33,6 +34,7 @@ public sealed class DriverHost : IAsyncDisposable
     ///     startup. Returns null when the driver is not registered.
     /// </summary>
     /// <param name="driverInstanceId">The driver instance identifier to look up.</param>
+    /// <returns>The driver instance if registered; otherwise null.</returns>
     public IDriver? GetDriver(string driverInstanceId)
     {
         lock (_lock)
@@ -47,6 +49,7 @@ public sealed class DriverHost : IAsyncDisposable
     /// <param name="driver">The driver instance to register.</param>
     /// <param name="driverConfigJson">The configuration JSON for the driver.</param>
     /// <param name="ct">Cancellation token for the operation.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public async Task RegisterAsync(IDriver driver, string driverConfigJson, CancellationToken ct)
     {
         ArgumentNullException.ThrowIfNull(driver);
@@ -70,6 +73,7 @@ public sealed class DriverHost : IAsyncDisposable
     /// <summary>Unregisters a driver and calls shutdown.</summary>
     /// <param name="driverInstanceId">The driver instance identifier to unregister.</param>
     /// <param name="ct">Cancellation token for the operation.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     public async Task UnregisterAsync(string driverInstanceId, CancellationToken ct)
     {
         IDriver? driver;
@@ -84,6 +88,7 @@ public sealed class DriverHost : IAsyncDisposable
     }
 
     /// <summary>Disposes the driver host and all registered drivers.</summary>
+    /// <returns>A value task that represents the asynchronous operation.</returns>
     public async ValueTask DisposeAsync()
     {
         List<IDriver> snapshot;

src/Core/ZB.MOM.WW.OtOpcUa.Core/Observability/DriverHealthReport.cs

@@ -27,6 +27,7 @@ public static class DriverHealthReport
 {
     /// <summary>Compute the fleet-wide readiness verdict from per-driver states.</summary>
     /// <param name="drivers">The list of per-driver health snapshots to aggregate.</param>
+    /// <returns>The fleet-wide <see cref="ReadinessVerdict"/> derived from all driver states.</returns>
     public static ReadinessVerdict Aggregate(IReadOnlyList<DriverHealthSnapshot> drivers)
     {
         ArgumentNullException.ThrowIfNull(drivers);
@@ -54,6 +55,7 @@ public static class DriverHealthReport
     ///     return per the Stream C.1 state matrix.
     /// </summary>
     /// <param name="verdict">The readiness verdict to map to HTTP status.</param>
+    /// <returns>The HTTP status code (200 or 503) corresponding to the verdict.</returns>
     public static int HttpStatus(ReadinessVerdict verdict) => verdict switch
     {
         ReadinessVerdict.Healthy => 200,

src/Core/ZB.MOM.WW.OtOpcUa.Core/Observability/LogContextEnricher.cs

@@ -22,6 +22,7 @@ public static class LogContextEnricher
     /// <param name="driverType">The driver type name.</param>
     /// <param name="capability">The driver capability being invoked.</param>
     /// <param name="correlationId">The correlation ID for tracing the call.</param>
+    /// <returns>A scope that pops the pushed properties when disposed.</returns>
     public static IDisposable Push(string driverInstanceId, string driverType, DriverCapability capability, string correlationId)
     {
         ArgumentException.ThrowIfNullOrWhiteSpace(driverInstanceId);
@@ -40,6 +41,7 @@ public static class LogContextEnricher
     ///     12-hex-char slice of a GUID — long enough for log correlation, short enough to
     ///     scan visually.
     /// </summary>
+    /// <returns>A 12-character hex string suitable for log correlation.</returns>
     public static string NewCorrelationId() => Guid.NewGuid().ToString("N")[..12];
 
     private sealed class CompositeScope : IDisposable

src/Core/ZB.MOM.WW.OtOpcUa.Core/OpcUa/EquipmentNodeWalker.cs

@@ -183,6 +183,7 @@ public static class EquipmentNodeWalker
     ///     wants an opaque non-JSON reference.
     /// </remarks>
     /// <param name="tagConfig">The tag configuration JSON or string.</param>
+    /// <returns>The value of the <c>FullName</c> field from the JSON, or the raw <paramref name="tagConfig"/> string as a fallback.</returns>
     internal static string ExtractFullName(string tagConfig)
     {
         if (string.IsNullOrWhiteSpace(tagConfig)) return tagConfig;

src/Core/ZB.MOM.WW.OtOpcUa.Core/OpcUa/GenericDriverNodeManager.cs

@@ -49,6 +49,7 @@ public class GenericDriverNodeManager(IDriver driver) : IDisposable
     /// </summary>
     /// <param name="builder">The address space builder to populate.</param>
     /// <param name="ct">The cancellation token.</param>
+    /// <returns>A task that represents the asynchronous address space build operation.</returns>
     public async Task BuildAddressSpaceAsync(IAddressSpaceBuilder builder, CancellationToken ct)
     {
         ArgumentNullException.ThrowIfNull(builder);
@@ -111,23 +112,15 @@ public class GenericDriverNodeManager(IDriver driver) : IDisposable
         IAddressSpaceBuilder inner,
         ConcurrentDictionary<string, IAlarmConditionSink> sinks) : IAddressSpaceBuilder
     {
-        /// <summary>Adds a folder to the address space.</summary>
+        /// <inheritdoc />
-        /// <param name="browseName">The browse name of the folder node.</param>
-        /// <param name="displayName">The display name of the folder node.</param>
         public IAddressSpaceBuilder Folder(string browseName, string displayName)
             => new CapturingBuilder(inner.Folder(browseName, displayName), sinks);
 
-        /// <summary>Adds a variable to the address space.</summary>
+        /// <inheritdoc />
-        /// <param name="browseName">The browse name of the variable node.</param>
-        /// <param name="displayName">The display name of the variable node.</param>
-        /// <param name="attributeInfo">Metadata describing the variable's data type and properties.</param>
         public IVariableHandle Variable(string browseName, string displayName, DriverAttributeInfo attributeInfo)
             => new CapturingHandle(inner.Variable(browseName, displayName, attributeInfo), sinks);
 
-        /// <summary>Adds a property to the address space.</summary>
+        /// <inheritdoc />
-        /// <param name="browseName">The browse name of the property node.</param>
-        /// <param name="dataType">The OPC UA data type of the property.</param>
-        /// <param name="value">The initial value of the property, or null.</param>
         public void AddProperty(string browseName, DriverDataType dataType, object? value)
             => inner.AddProperty(browseName, dataType, value);
     }
@@ -136,11 +129,10 @@ public class GenericDriverNodeManager(IDriver driver) : IDisposable
         IVariableHandle inner,
         ConcurrentDictionary<string, IAlarmConditionSink> sinks) : IVariableHandle
     {
-        /// <summary>Gets the full reference for the variable.</summary>
+        /// <inheritdoc />
         public string FullReference => inner.FullReference;
 
-        /// <summary>Marks the variable as an alarm condition and registers its sink.</summary>
+        /// <inheritdoc />
-        /// <param name="info">Configuration for the alarm condition.</param>
         public IAlarmConditionSink MarkAsAlarmCondition(AlarmConditionInfo info)
         {
             var sink = inner.MarkAsAlarmCondition(info);

src/Core/ZB.MOM.WW.OtOpcUa.Core/Resilience/AlarmSurfaceInvoker.cs

@@ -59,6 +59,7 @@ public sealed class AlarmSurfaceInvoker
     /// </summary>
     /// <param name="sourceNodeIds">The source node IDs to subscribe to.</param>
     /// <param name="cancellationToken">The cancellation token.</param>
+    /// <returns>A task that resolves to one subscription handle per resolved host.</returns>
     public async Task<IReadOnlyList<IAlarmSubscriptionHandle>> SubscribeAsync(
         IReadOnlyList<string> sourceNodeIds,
         CancellationToken cancellationToken)
@@ -89,6 +90,7 @@ public sealed class AlarmSurfaceInvoker
     /// </summary>
     /// <param name="handle">The subscription handle to unsubscribe.</param>
     /// <param name="cancellationToken">The cancellation token.</param>
+    /// <returns>A task that represents the asynchronous unsubscribe operation.</returns>
     public ValueTask UnsubscribeAsync(IAlarmSubscriptionHandle handle, CancellationToken cancellationToken)
     {
         ArgumentNullException.ThrowIfNull(handle);
@@ -110,6 +112,7 @@ public sealed class AlarmSurfaceInvoker
     /// </summary>
     /// <param name="acknowledgements">The alarm acknowledgement requests.</param>
     /// <param name="cancellationToken">The cancellation token.</param>
+    /// <returns>A task that represents the asynchronous acknowledgement operation.</returns>
     public async Task AcknowledgeAsync(
         IReadOnlyList<AlarmAcknowledgeRequest> acknowledgements,
         CancellationToken cancellationToken)
@@ -166,7 +169,7 @@ public sealed class AlarmSurfaceInvoker
         public IAlarmSubscriptionHandle Inner { get; } = inner;
         /// <summary>Gets the resolved host name.</summary>
         public string Host { get; } = host;
-        /// <summary>Gets the diagnostic ID from the inner handle.</summary>
+        /// <inheritdoc />
         public string DiagnosticId => Inner.DiagnosticId;
     }
 }

src/Core/ZB.MOM.WW.OtOpcUa.Core/Resilience/CapabilityInvoker.cs

@@ -58,6 +58,7 @@ public sealed class CapabilityInvoker
     /// <param name="hostName">The host name for logging and status tracking.</param>
     /// <param name="callSite">The async function to execute.</param>
     /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>The result produced by <paramref name="callSite"/> after executing through the pipeline.</returns>
     public async ValueTask<TResult> ExecuteAsync<TResult>(
         DriverCapability capability,
         string hostName,
@@ -86,6 +87,7 @@ public sealed class CapabilityInvoker
     /// <param name="hostName">The host name for logging and status tracking.</param>
     /// <param name="callSite">The async function to execute.</param>
     /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>A value task that represents the asynchronous operation.</returns>
     public async ValueTask ExecuteAsync(
         DriverCapability capability,
         string hostName,
@@ -121,6 +123,7 @@ public sealed class CapabilityInvoker
     /// <param name="isIdempotent">Whether the write operation is idempotent.</param>
     /// <param name="callSite">The async function to execute.</param>
     /// <param name="cancellationToken">Cancellation token for the operation.</param>
+    /// <returns>The result produced by <paramref name="callSite"/> after executing through the write pipeline.</returns>
     public async ValueTask<TResult> ExecuteWriteAsync<TResult>(
         string hostName,
         bool isIdempotent,

src/Core/ZB.MOM.WW.OtOpcUa.Core/Resilience/DriverResilienceOptionsParser.cs

@@ -50,6 +50,7 @@ public static class DriverResilienceOptionsParser
     /// <param name="tier">The driver tier for default resilience options.</param>
     /// <param name="resilienceConfigJson">The optional JSON configuration string to parse.</param>
     /// <param name="parseDiagnostic">An out parameter containing diagnostic information if parsing fails.</param>
+    /// <returns>The effective resilience options; tier defaults when the JSON is null or malformed.</returns>
     public static DriverResilienceOptions ParseOrDefaults(
         DriverTier tier,
         string? resilienceConfigJson,

src/Core/ZB.MOM.WW.OtOpcUa.Core/Resilience/DriverResiliencePipelineBuilder.cs

@@ -54,6 +54,7 @@ public sealed class DriverResiliencePipelineBuilder
     /// </param>
     /// <param name="capability">Which capability surface is being called.</param>
     /// <param name="options">Per-driver-instance options (tier + per-capability overrides).</param>
+    /// <returns>The cached or newly created <see cref="ResiliencePipeline"/> for the given key.</returns>
     public ResiliencePipeline GetOrCreate(
         string driverInstanceId,
         string hostName,

src/Core/ZB.MOM.WW.OtOpcUa.Core/Resilience/DriverResilienceStatusTracker.cs

@@ -128,10 +128,12 @@ public sealed class DriverResilienceStatusTracker
     /// <summary>Snapshot of a specific (instance, host) pair; null if no counters recorded yet.</summary>
     /// <param name="driverInstanceId">The driver instance identifier.</param>
     /// <param name="hostName">The host name.</param>
+    /// <returns>The current <see cref="ResilienceStatusSnapshot"/> for the pair, or <see langword="null"/> if no counters have been recorded.</returns>
     public ResilienceStatusSnapshot? TryGet(string driverInstanceId, string hostName) =>
         _status.TryGetValue(new StatusKey(driverInstanceId, hostName), out var snapshot) ? snapshot : null;
 
     /// <summary>Copy of every currently-tracked (instance, host, snapshot) triple. Safe under concurrent writes.</summary>
+    /// <returns>A snapshot list of all currently tracked driver instance and host resilience states.</returns>
     public IReadOnlyList<(string DriverInstanceId, string HostName, ResilienceStatusSnapshot Snapshot)> Snapshot() =>
         _status.Select(kvp => (kvp.Key.DriverInstanceId, kvp.Key.HostName, kvp.Value)).ToList();
 

src/Core/ZB.MOM.WW.OtOpcUa.Core/Stability/MemoryTracking.cs

@@ -33,6 +33,7 @@ public sealed class MemoryTracking
 
     /// <summary>Tier-default multiplier/floor constants per decision #146.</summary>
     /// <param name="tier">The driver tier.</param>
+    /// <returns>A tuple with the growth multiplier and the minimum floor bytes for the specified tier.</returns>
     public static (int Multiplier, long FloorBytes) GetTierConstants(DriverTier tier) => tier switch
     {
         DriverTier.A => (Multiplier: 3, FloorBytes: 50L * 1024 * 1024),
@@ -73,6 +74,7 @@ public sealed class MemoryTracking
     /// </summary>
     /// <param name="footprintBytes">The current memory footprint in bytes.</param>
     /// <param name="utcNow">The current UTC time.</param>
+    /// <returns>The <see cref="MemoryTrackingAction"/> classifying this sample against the soft/hard thresholds.</returns>
     public MemoryTrackingAction Sample(long footprintBytes, DateTime utcNow)
     {
         if (_phase == TrackingPhase.WarmingUp)

src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli/AbCipCommandBase.cs

@@ -60,6 +60,7 @@ public abstract class AbCipCommandBase : DriverCommandBase
     ///     probe loop would race the operator's own reads.
     /// </summary>
     /// <param name="tags">The list of tag definitions to include in the options.</param>
+    /// <returns>A fully-configured <see cref="AbCipDriverOptions"/> with probe and alarm projection disabled.</returns>
     protected AbCipDriverOptions BuildOptions(IReadOnlyList<AbCipTagDefinition> tags) => new()
     {
         Devices = [new AbCipDeviceOptions(

src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.AbCip.Cli/Commands/ReadCommand.cs

@@ -66,6 +66,7 @@ public sealed class ReadCommand : AbCipCommandBase
     /// </summary>
     /// <param name="tagPath">The symbolic tag path.</param>
     /// <param name="type">The data type.</param>
+    /// <returns>A combined tag-name string in <c>path:type</c> form.</returns>
     internal static string SynthesiseTagName(string tagPath, AbCipDataType type)
         => $"{tagPath}:{type}";
 }

src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Cli/Commands/ReadCommand.cs

@@ -58,6 +58,7 @@ public sealed class ReadCommand : AbLegacyCommandBase
     /// <summary>Tag-name key the driver uses internally. Address+type is already unique.</summary>
     /// <param name="address">The PCCC file address.</param>
     /// <param name="type">The data type of the address.</param>
+    /// <returns>A combined tag name string in the form <c>address:type</c>.</returns>
     internal static string SynthesiseTagName(string address, AbLegacyDataType type)
         => $"{address}:{type}";
 }

src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.Cli.Common/SnapshotFormatter.cs

@@ -23,6 +23,7 @@ public static class SnapshotFormatter
     /// </summary>
     /// <param name="tagName">The tag name to include in the output.</param>
     /// <param name="snapshot">The data value snapshot to format.</param>
+    /// <returns>A multi-line string representation of the tag and its value.</returns>
     public static string Format(string tagName, DataValueSnapshot snapshot)
     {
         ArgumentNullException.ThrowIfNull(snapshot);
@@ -42,6 +43,7 @@ public static class SnapshotFormatter
     /// </summary>
     /// <param name="tagName">The tag name to include in the output.</param>
     /// <param name="result">The write result to format.</param>
+    /// <returns>A single-line string showing the tag name and write status.</returns>
     public static string FormatWrite(string tagName, WriteResult result)
     {
         ArgumentNullException.ThrowIfNull(result);
@@ -54,6 +56,7 @@ public static class SnapshotFormatter
     /// </summary>
     /// <param name="tagNames">The list of tag names to include as rows.</param>
     /// <param name="snapshots">The list of data value snapshots to format.</param>
+    /// <returns>An aligned table string with tag, value, status, and source-time columns.</returns>
     public static string FormatTable(
         IReadOnlyList<string> tagNames, IReadOnlyList<DataValueSnapshot> snapshots)
     {

src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Cli/Commands/ReadCommand.cs

@@ -52,6 +52,7 @@ public sealed class ReadCommand : FocasCommandBase
     /// <summary>Constructs a tag name from address and data type.</summary>
     /// <param name="address">The FOCAS address.</param>
     /// <param name="type">The data type.</param>
+    /// <returns>A synthesized tag name string combining the address and data type.</returns>
     internal static string SynthesiseTagName(string address, FocasDataType type)
         => $"{address}:{type}";
 }

src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Cli/FocasCommandBase.cs

@@ -47,6 +47,7 @@ public abstract class FocasCommandBase : DriverCommandBase
     ///     as <c>BadCommunicationError</c>.
     /// </summary>
     /// <param name="tags">The tag definitions to include in the driver options.</param>
+    /// <returns>A <see cref="FocasDriverOptions"/> configured with the CNC target and the supplied tag list.</returns>
     protected FocasDriverOptions BuildOptions(IReadOnlyList<FocasTagDefinition> tags) => new()
     {
         Devices = [new FocasDeviceOptions(

src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.Modbus.Cli/ModbusCommandBase.cs

@@ -48,6 +48,7 @@ public abstract class ModbusCommandBase : DriverCommandBase
     ///     command against its own keep-alive reads.
     /// </summary>
     /// <param name="tags">The tag definitions to include in the options.</param>
+    /// <returns>A <see cref="ModbusDriverOptions"/> configured for a one-shot CLI run.</returns>
     protected ModbusDriverOptions BuildOptions(IReadOnlyList<ModbusTagDefinition> tags) => new()
     {
         Host = Host,

src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.S7.Cli/Commands/ReadCommand.cs

@@ -61,6 +61,7 @@ public sealed class ReadCommand : S7CommandBase
     /// <summary>Tag-name key used internally. Address + type is already unique.</summary>
     /// <param name="address">The S7 address to encode in the tag name.</param>
     /// <param name="type">The data type to encode in the tag name.</param>
+    /// <returns>The synthesised tag name encoding the address and type.</returns>
     internal static string SynthesiseTagName(string address, S7DataType type)
         => $"{address}:{type}";
 }

src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.S7.Cli/S7CommandBase.cs

@@ -51,6 +51,7 @@ public abstract class S7CommandBase : DriverCommandBase
     ///     disabled — CLI runs are one-shot.
     /// </summary>
     /// <param name="tags">The tag definitions to include in the options.</param>
+    /// <returns>An <see cref="S7DriverOptions"/> populated with the current command-line values and the supplied tags.</returns>
     protected S7DriverOptions BuildOptions(IReadOnlyList<S7TagDefinition> tags) => new()
     {
         Host = Host,

src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.Cli/Commands/BrowseCommand.cs

@@ -90,6 +90,7 @@ public sealed class BrowseCommand : TwinCATCommandBase
     /// </summary>
     /// <param name="source">The source collection to filter.</param>
     /// <param name="prefix">The prefix to filter on, or null to keep everything.</param>
+    /// <returns>A filtered list of variables whose browse names start with the given prefix.</returns>
     internal static List<(string BrowseName, DriverAttributeInfo Info)> FilterByPrefix(
         IReadOnlyList<(string BrowseName, DriverAttributeInfo Info)> source, string? prefix)
         => source
@@ -102,6 +103,7 @@ public sealed class BrowseCommand : TwinCATCommandBase
     /// </summary>
     /// <param name="matchedCount">The number of matched items.</param>
     /// <param name="max">The maximum number to show, or 0 for unbounded.</param>
+    /// <returns>The effective print limit: <paramref name="matchedCount"/> when unbounded, otherwise the lesser of <paramref name="max"/> and <paramref name="matchedCount"/>.</returns>
     internal static int PrintLimit(int matchedCount, int max)
         => max <= 0 ? matchedCount : Math.Min(max, matchedCount);
 
@@ -112,6 +114,7 @@ public sealed class BrowseCommand : TwinCATCommandBase
     ///     authorization is enforced server-side.
     /// </summary>
     /// <param name="info">The attribute info to label.</param>
+    /// <returns>"RO" for view-only attributes; "RW" for all others.</returns>
     internal static string AccessTag(DriverAttributeInfo info)
         => info.SecurityClass == SecurityClassification.ViewOnly ? "RO" : "RW";
 

src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.Cli/Commands/WriteCommand.cs

@@ -69,6 +69,7 @@ public sealed class WriteCommand : TwinCATTagCommandBase
     /// <summary>Parse <c>--value</c> per <see cref="TwinCATDataType"/>, invariant culture.</summary>
     /// <param name="raw">The raw string value to parse.</param>
     /// <param name="type">The target TwinCAT data type.</param>
+    /// <returns>The parsed value as a boxed .NET object matching the requested data type.</returns>
     internal static object ParseValue(string raw, TwinCATDataType type) => type switch
     {
         TwinCATDataType.Bool => ParseBool(raw),

src/Drivers/Cli/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.Cli/TwinCATTagCommandBase.cs

@@ -24,6 +24,7 @@ public abstract class TwinCATTagCommandBase : TwinCATCommandBase
     ///     native notifications toggled by <see cref="PollOnly"/>.
     /// </summary>
     /// <param name="tags">Tag definitions for the driver.</param>
+    /// <returns>A <see cref="TwinCATDriverOptions"/> configured for a single-device CLI run.</returns>
     protected TwinCATDriverOptions BuildOptions(IReadOnlyList<TwinCATTagDefinition> tags) => new()
     {
         Devices = [new TwinCATDeviceOptions(
@@ -39,6 +40,7 @@ public abstract class TwinCATTagCommandBase : TwinCATCommandBase
     // ---- Test hook ----
     /// <summary>Test hook that exposes BuildOptions for unit testing.</summary>
     /// <param name="tags">Tag definitions for the driver.</param>
+    /// <returns>A <see cref="TwinCATDriverOptions"/> configured for a single-device CLI run.</returns>
     internal TwinCATDriverOptions BuildOptionsForTest(IReadOnlyList<TwinCATTagDefinition> tags)
         => BuildOptions(tags);
 }

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/AbCipDriver.cs

@@ -130,10 +130,10 @@ public sealed class AbCipDriver : IDriver, IReadable, IWritable, ITagDiscovery,
     /// </summary>
     internal AbCipTemplateCache TemplateCache => _templateCache;
 
-    /// <summary>Gets the unique identifier for this driver instance.</summary>
+    /// <inheritdoc />
     public string DriverInstanceId => _driverInstanceId;
 
-    /// <summary>Gets the driver type identifier.</summary>
+    /// <inheritdoc />
     public string DriverType => "AbCip";
 
     /// <summary>
@@ -244,10 +244,7 @@ public sealed class AbCipDriver : IDriver, IReadable, IWritable, ITagDiscovery,
         return Task.CompletedTask;
     }
 
-    /// <summary>Reinitialize the driver by shutting down and reinitializing with new configuration.</summary>
+    /// <inheritdoc />
-    /// <param name="driverConfigJson">The new driver configuration as JSON.</param>
-    /// <param name="cancellationToken">Cancellation token for the operation.</param>
-    /// <returns>A task representing the asynchronous reinitialization.</returns>
     public async Task ReinitializeAsync(string driverConfigJson, CancellationToken cancellationToken)
     {
         await ShutdownAsync(cancellationToken).ConfigureAwait(false);
@@ -305,19 +302,12 @@ public sealed class AbCipDriver : IDriver, IReadable, IWritable, ITagDiscovery,
 
     // ---- ISubscribable (polling overlay via shared engine) ----
 
-    /// <summary>Subscribe to value changes for the specified tag references.</summary>
+    /// <inheritdoc />
-    /// <param name="fullReferences">The tag references to subscribe to.</param>
-    /// <param name="publishingInterval">The interval at which to publish changes.</param>
-    /// <param name="cancellationToken">Cancellation token for the operation.</param>
-    /// <returns>A handle representing the subscription.</returns>
     public Task<ISubscriptionHandle> SubscribeAsync(
         IReadOnlyList<string> fullReferences, TimeSpan publishingInterval, CancellationToken cancellationToken) =>
         Task.FromResult(_poll.Subscribe(fullReferences, publishingInterval));
 
-    /// <summary>Unsubscribe from value changes using a subscription handle.</summary>
+    /// <inheritdoc />
-    /// <param name="handle">The subscription handle to unsubscribe.</param>
-    /// <param name="cancellationToken">Cancellation token for the operation.</param>
-    /// <returns>A completed task.</returns>
     public Task UnsubscribeAsync(ISubscriptionHandle handle, CancellationToken cancellationToken)
     {
         _poll.Unsubscribe(handle);
@@ -349,19 +339,13 @@ public sealed class AbCipDriver : IDriver, IReadable, IWritable, ITagDiscovery,
         return _alarmProjection.SubscribeAsync(sourceNodeIds, cancellationToken);
     }
 
-    /// <summary>Unsubscribe from alarm events.</summary>
+    /// <inheritdoc />
-    /// <param name="handle">The alarm subscription handle.</param>
-    /// <param name="cancellationToken">Cancellation token for the operation.</param>
-    /// <returns>A completed task.</returns>
     public Task UnsubscribeAlarmsAsync(IAlarmSubscriptionHandle handle, CancellationToken cancellationToken) =>
         _options.EnableAlarmProjection
             ? _alarmProjection.UnsubscribeAsync(handle, cancellationToken)
             : Task.CompletedTask;
 
-    /// <summary>Acknowledge alarms.</summary>
+    /// <inheritdoc />
-    /// <param name="acknowledgements">The alarm acknowledgements to process.</param>
-    /// <param name="cancellationToken">Cancellation token for the operation.</param>
-    /// <returns>A completed task.</returns>
     public Task AcknowledgeAsync(
         IReadOnlyList<AlarmAcknowledgeRequest> acknowledgements, CancellationToken cancellationToken) =>
         _options.EnableAlarmProjection
@@ -370,8 +354,7 @@ public sealed class AbCipDriver : IDriver, IReadable, IWritable, ITagDiscovery,
 
     // ---- IHostConnectivityProbe ----
 
-    /// <summary>Gets the connectivity status of all configured devices.</summary>
+    /// <inheritdoc />
-    /// <returns>A read-only list of host connectivity statuses.</returns>
     public IReadOnlyList<HostConnectivityStatus> GetHostStatuses() =>
         [.. _devices.Values.Select(s => new HostConnectivityStatus(s.Options.HostAddress, s.HostState, s.HostStateChangedUtc))];
 
@@ -873,8 +856,7 @@ public sealed class AbCipDriver : IDriver, IReadable, IWritable, ITagDiscovery,
         }
     }
 
-    /// <summary>Gets the current health status of the driver.</summary>
+    /// <inheritdoc />
-    /// <returns>The driver health information.</returns>
     public DriverHealth GetHealth() => _health;
 
     /// <summary>
@@ -885,9 +867,7 @@ public sealed class AbCipDriver : IDriver, IReadable, IWritable, ITagDiscovery,
     /// <returns>The memory footprint in bytes.</returns>
     public long GetMemoryFootprint() => 0;
 
-    /// <summary>Flushes optional caches to free memory.</summary>
+    /// <inheritdoc />
-    /// <param name="cancellationToken">Cancellation token for the operation.</param>
-    /// <returns>A completed task.</returns>
     public Task FlushOptionalCachesAsync(CancellationToken cancellationToken)
     {
         _templateCache.Clear();

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/AbCipStatusMapper.cs

@@ -48,6 +48,7 @@ public static class AbCipStatusMapper
 
     /// <summary>Map a CIP general-status byte to an OPC UA StatusCode.</summary>
     /// <param name="status">The CIP general-status byte value.</param>
+    /// <returns>The corresponding OPC UA StatusCode.</returns>
     public static uint MapCipGeneralStatus(byte status) => status switch
     {
         0x00 => Good,
@@ -72,6 +73,7 @@ public static class AbCipStatusMapper
     ///     operation; every other (negative) member is an error.
     /// </summary>
     /// <param name="status">The libplctag status code as an integer.</param>
+    /// <returns>The corresponding OPC UA StatusCode.</returns>
     public static uint MapLibplctagStatus(int status) => MapLibplctagStatus((Status)status);
 
     /// <summary>
@@ -80,6 +82,7 @@ public static class AbCipStatusMapper
     ///     <see cref="IAbCipTagRuntime.GetStatus"/> seam, which returns the boxed-as-int value.
     /// </summary>
     /// <param name="status">The libplctag Status enum value.</param>
+    /// <returns>The corresponding OPC UA StatusCode.</returns>
     public static uint MapLibplctagStatus(Status status) => status switch
     {
         Status.Ok => Good,

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/AbCipSystemTagFilter.cs

@@ -19,6 +19,7 @@ public static class AbCipSystemTagFilter
     ///     always preserved case and the system-tag prefixes are uppercase by convention.
     /// </summary>
     /// <param name="tagName">The tag name to check.</param>
+    /// <returns><see langword="true"/> if the tag is a system tag that should be hidden; otherwise <see langword="false"/>.</returns>
     public static bool IsSystemTag(string tagName)
     {
         if (string.IsNullOrWhiteSpace(tagName)) return true;

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/AbCipTagPath.cs

@@ -24,6 +24,7 @@ public sealed record AbCipTagPath(
     int? BitIndex)
 {
     /// <summary>Rebuild the canonical Logix tag string.</summary>
+    /// <returns>The canonical Logix tag string suitable for the libplctag <c>name=</c> attribute.</returns>
     public string ToLibplctagName()
     {
         var buf = new System.Text.StringBuilder();

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/AbCipTemplateCache.cs

@@ -23,6 +23,7 @@ public sealed class AbCipTemplateCache
     /// </summary>
     /// <param name="deviceHostAddress">The device host address and port.</param>
     /// <param name="templateInstanceId">The template instance ID.</param>
+    /// <returns>The cached <see cref="AbCipUdtShape"/>, or <c>null</c> if not yet populated.</returns>
     public AbCipUdtShape? TryGet(string deviceHostAddress, uint templateInstanceId) =>
         _shapes.TryGetValue((deviceHostAddress, templateInstanceId), out var shape) ? shape : null;
 

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/AbCipUdtMemberLayout.cs

@@ -30,6 +30,7 @@ public static class AbCipUdtMemberLayout
     ///     if any member type is unsupported for declaration-only layout.
     /// </summary>
     /// <param name="members">The list of UDT member declarations.</param>
+    /// <returns>A dictionary mapping member name to byte offset, or <see langword="null"/> if any member type is unsupported.</returns>
     public static IReadOnlyDictionary<string, int>? TryBuild(
         IReadOnlyList<AbCipStructureMember> members)
     {

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/AbCipUdtReadPlanner.cs

@@ -28,6 +28,7 @@ public static class AbCipUdtReadPlanner
     /// <param name="requests">The list of tag references to read.</param>
     /// <param name="tagsByName">Dictionary mapping tag names to their definitions.</param>
     /// <param name="enableDeclarationOnlyGrouping">Whether to enable UDT member grouping based on declaration order.</param>
+    /// <returns>An <see cref="AbCipUdtReadPlan"/> partitioning requests into whole-UDT groups and per-tag fallbacks.</returns>
     public static AbCipUdtReadPlan Build(
         IReadOnlyList<string> requests,
         IReadOnlyDictionary<string, AbCipTagDefinition> tagsByName,

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/IAbCipTagEnumerator.cs

@@ -15,6 +15,7 @@ public interface IAbCipTagEnumerator : IDisposable
     /// </summary>
     /// <param name="deviceParams">Parameters for creating device tags.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>An async enumerable of discovered tags.</returns>
     IAsyncEnumerable<AbCipDiscoveredTag> EnumerateAsync(
         AbCipTagCreateParams deviceParams,
         CancellationToken cancellationToken);
@@ -26,6 +27,7 @@ public interface IAbCipTagEnumeratorFactory
     /// <summary>
     /// Creates a new tag enumerator instance.
     /// </summary>
+    /// <returns>A new <see cref="IAbCipTagEnumerator"/> instance.</returns>
     IAbCipTagEnumerator Create();
 }
 
@@ -59,6 +61,7 @@ internal sealed class EmptyAbCipTagEnumerator : IAbCipTagEnumerator
     /// </summary>
     /// <param name="deviceParams">Parameters for creating device tags.</param>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>An empty async enumerable of discovered tags.</returns>
     public async IAsyncEnumerable<AbCipDiscoveredTag> EnumerateAsync(
         AbCipTagCreateParams deviceParams,
         [System.Runtime.CompilerServices.EnumeratorCancellation] CancellationToken cancellationToken)
@@ -79,5 +82,6 @@ internal sealed class EmptyAbCipTagEnumeratorFactory : IAbCipTagEnumeratorFactor
     /// <summary>
     /// Creates a new empty tag enumerator.
     /// </summary>
+    /// <returns>A new <see cref="EmptyAbCipTagEnumerator"/> instance.</returns>
     public IAbCipTagEnumerator Create() => new EmptyAbCipTagEnumerator();
 }

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/IAbCipTagRuntime.cs

@@ -11,20 +11,24 @@ public interface IAbCipTagRuntime : IDisposable
 {
     /// <summary>Create the underlying native tag (equivalent to libplctag's <c>plc_tag_create</c>).</summary>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task InitializeAsync(CancellationToken cancellationToken);
 
     /// <summary>Issue a read; on completion the local buffer holds the current PLC value.</summary>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task ReadAsync(CancellationToken cancellationToken);
 
     /// <summary>Flush the local buffer to the PLC.</summary>
     /// <param name="cancellationToken">Cancellation token.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     Task WriteAsync(CancellationToken cancellationToken);
 
     /// <summary>
     ///     Raw libplctag status code — mapped to an OPC UA StatusCode via
     ///     <see cref="AbCipStatusMapper.MapLibplctagStatus(int)"/>. Zero on success, negative on error.
     /// </summary>
+    /// <returns>The raw libplctag status integer; zero on success, negative on error.</returns>
     int GetStatus();
 
     /// <summary>
@@ -34,6 +38,7 @@ public interface IAbCipTagRuntime : IDisposable
     /// </summary>
     /// <param name="type">CIP data type to decode.</param>
     /// <param name="bitIndex">Bit index for BOOL-within-DINT extraction, or null.</param>
+    /// <returns>The decoded .NET value, or <c>null</c> if the buffer cannot be decoded for the given type.</returns>
     object? DecodeValue(AbCipDataType type, int? bitIndex);
 
     /// <summary>
@@ -48,6 +53,7 @@ public interface IAbCipTagRuntime : IDisposable
     /// <param name="type">CIP data type to decode.</param>
     /// <param name="offset">Byte offset in the buffer.</param>
     /// <param name="bitIndex">Bit index for BOOL-within-DINT extraction, or null.</param>
+    /// <returns>The decoded .NET value at the specified offset, or <c>null</c> if the offset is unsupported.</returns>
     object? DecodeValueAt(AbCipDataType type, int offset, int? bitIndex);
 
     /// <summary>
@@ -68,6 +74,7 @@ public interface IAbCipTagFactory
 {
     /// <summary>Creates a tag runtime handle from the specified creation parameters.</summary>
     /// <param name="createParams">Parameters needed to create the tag runtime.</param>
+    /// <returns>A new <see cref="IAbCipTagRuntime"/> instance for the specified tag.</returns>
     IAbCipTagRuntime Create(AbCipTagCreateParams createParams);
 }