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).

tests/Client/ZB.MOM.WW.OtOpcUa.Client.UI.Tests/SubscriptionsViewModelTests.cs

@@ -41,6 +41,7 @@ public class SubscriptionsViewModelTests
     }
 
     /// <summary>Verifies that AddSubscriptionCommand adds a new subscription to the active list.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task AddSubscriptionCommand_AddsItem()
     {
@@ -58,6 +59,7 @@ public class SubscriptionsViewModelTests
     }
 
     /// <summary>Verifies that RemoveSubscriptionCommand removes selected subscription.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task RemoveSubscriptionCommand_RemovesItem()
     {
@@ -83,6 +85,7 @@ public class SubscriptionsViewModelTests
     }
 
     /// <summary>Verifies that DataChanged event updates the matching subscription row.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task DataChanged_UpdatesMatchingRow()
     {
@@ -98,6 +101,7 @@ public class SubscriptionsViewModelTests
     }
 
     /// <summary>Verifies that DataChanged event does not update non-matching subscription rows.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task DataChanged_DoesNotUpdateNonMatchingRow()
     {
@@ -146,6 +150,7 @@ public class SubscriptionsViewModelTests
     }
 
     /// <summary>Verifies that AddSubscriptionForNodeAsync adds a subscription.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task AddSubscriptionForNodeAsync_AddsSubscription()
     {
@@ -160,6 +165,7 @@ public class SubscriptionsViewModelTests
     }
 
     /// <summary>Verifies that AddSubscriptionForNodeAsync skips duplicate subscriptions.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task AddSubscriptionForNodeAsync_SkipsDuplicate()
     {
@@ -173,6 +179,7 @@ public class SubscriptionsViewModelTests
     }
 
     /// <summary>Verifies that AddSubscriptionForNodeAsync does nothing when disconnected.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task AddSubscriptionForNodeAsync_DoesNothing_WhenDisconnected()
     {
@@ -185,6 +192,7 @@ public class SubscriptionsViewModelTests
     }
 
     /// <summary>Verifies that GetSubscribedNodeIds returns all active subscription node IDs.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task GetSubscribedNodeIds_ReturnsActiveNodeIds()
     {
@@ -200,6 +208,7 @@ public class SubscriptionsViewModelTests
     }
 
     /// <summary>Verifies that RestoreSubscriptionsAsync subscribes to all provided node IDs.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task RestoreSubscriptionsAsync_SubscribesAllNodes()
     {
@@ -212,6 +221,7 @@ public class SubscriptionsViewModelTests
     }
 
     /// <summary>Verifies that ValidateAndWriteAsync returns true on successful write.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task ValidateAndWriteAsync_SuccessReturnsTrue()
     {
@@ -227,6 +237,7 @@ public class SubscriptionsViewModelTests
     }
 
     /// <summary>Verifies that ValidateAndWriteAsync returns false when value parsing fails.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task ValidateAndWriteAsync_ParseFailureReturnsFalse()
     {
@@ -242,6 +253,7 @@ public class SubscriptionsViewModelTests
     }
 
     /// <summary>Verifies that ValidateAndWriteAsync returns false when write fails.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task ValidateAndWriteAsync_WriteFailureReturnsFalse()
     {
@@ -256,6 +268,7 @@ public class SubscriptionsViewModelTests
     }
 
     /// <summary>Verifies that ValidateAndWriteAsync returns false when status is bad.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task ValidateAndWriteAsync_BadStatusReturnsFalse()
     {
@@ -270,6 +283,7 @@ public class SubscriptionsViewModelTests
     }
 
     /// <summary>Verifies that AddSubscriptionRecursiveAsync subscribes a variable directly.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task AddSubscriptionRecursiveAsync_SubscribesVariableDirectly()
     {
@@ -282,6 +296,7 @@ public class SubscriptionsViewModelTests
     }
 
     /// <summary>Verifies that AddSubscriptionRecursiveAsync browses objects and subscribes variable children.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task AddSubscriptionRecursiveAsync_BrowsesObjectAndSubscribesVariableChildren()
     {
@@ -302,6 +317,7 @@ public class SubscriptionsViewModelTests
     /// Regression test for Client.UI-006 — when SubscribeAsync throws, the failure must be surfaced
     /// to the operator via the view model's StatusMessage rather than silently swallowed.
     /// </summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task AddSubscription_OnFailure_SurfacesStatusMessage()
     {
@@ -320,6 +336,7 @@ public class SubscriptionsViewModelTests
     /// Regression test for Client.UI-006 — silent swallow when adding a subscription for a node
     /// (the context-menu helper) must also surface a status to the operator.
     /// </summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task AddSubscriptionForNodeAsync_OnFailure_SurfacesStatusMessage()
     {
@@ -334,6 +351,7 @@ public class SubscriptionsViewModelTests
     }
 
     /// <summary>Verifies that AddSubscriptionRecursiveAsync recurses through nested objects.</summary>
+    /// <returns>A task that represents the asynchronous test operation.</returns>
     [Fact]
     public async Task AddSubscriptionRecursiveAsync_RecursesNestedObjects()
     {