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/Core/ZB.MOM.WW.OtOpcUa.Core.Abstractions.Tests/PollGroupEngineTests.cs

@@ -35,6 +35,7 @@ public sealed class PollGroupEngineTests
     }
 
     /// <summary>Verifies that the initial poll forces an event for every subscribed tag.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Initial_poll_force_raises_every_subscribed_tag()
     {
@@ -54,6 +55,7 @@ public sealed class PollGroupEngineTests
     }
 
     /// <summary>Verifies that unchanged values are only raised once.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Unchanged_value_raises_only_once()
     {
@@ -72,6 +74,7 @@ public sealed class PollGroupEngineTests
     }
 
     /// <summary>Verifies that value changes raise new events.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Value_change_raises_new_event()
     {
@@ -92,6 +95,7 @@ public sealed class PollGroupEngineTests
     }
 
     /// <summary>Verifies that unsubscribe halts the polling loop.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Unsubscribe_halts_the_loop()
     {
@@ -113,6 +117,7 @@ public sealed class PollGroupEngineTests
     }
 
     /// <summary>Verifies that intervals below the configured floor are clamped.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Interval_below_floor_is_clamped()
     {
@@ -134,6 +139,7 @@ public sealed class PollGroupEngineTests
     }
 
     /// <summary>Verifies that multiple subscriptions operate independently.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Multiple_subscriptions_are_independent()
     {
@@ -165,6 +171,7 @@ public sealed class PollGroupEngineTests
     }
 
     /// <summary>Verifies that reader exceptions do not crash the polling loop.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Reader_exception_does_not_crash_loop()
     {
@@ -195,6 +202,7 @@ public sealed class PollGroupEngineTests
     }
 
     /// <summary>Verifies that unsubscribing an unknown handle returns false.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Unsubscribe_unknown_handle_returns_false()
     {
@@ -206,6 +214,7 @@ public sealed class PollGroupEngineTests
     }
 
     /// <summary>Verifies that the active subscription count tracks lifecycle changes.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task ActiveSubscriptionCount_tracks_lifecycle()
     {
@@ -225,6 +234,7 @@ public sealed class PollGroupEngineTests
     }
 
     /// <summary>Verifies that disposing the engine cancels all active subscriptions.</summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task DisposeAsync_cancels_all_subscriptions()
     {
@@ -253,6 +263,7 @@ public sealed class PollGroupEngineTests
     ///     must fire only the initial change event, not a spurious event on every tick, even
     ///     when the driver produces a fresh array instance on each read.
     /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Array_valued_tag_unchanged_contents_raises_only_once()
     {
@@ -289,6 +300,7 @@ public sealed class PollGroupEngineTests
     ///     Core.Abstractions-001: an array-valued tag whose contents change between polls
     ///     must fire a change event for each distinct set of contents.
     /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Array_valued_tag_changed_contents_raises_event()
     {
@@ -320,6 +332,7 @@ public sealed class PollGroupEngineTests
     ///     violates the documented contract. The engine must throw a descriptive exception
     ///     rather than silently stalling.
     /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Reader_short_result_list_raises_descriptive_exception_and_loop_continues()
     {
@@ -366,6 +379,7 @@ public sealed class PollGroupEngineTests
     ///     must continue to swallow exceptions (backward compatible). When an error callback IS
     ///     supplied, every exception caught during a poll cycle must be routed to it.
     /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Reader_exception_is_reported_to_onError_callback()
     {
@@ -401,6 +415,7 @@ public sealed class PollGroupEngineTests
     ///     must also be routed to the error callback so the driver health surface can observe
     ///     repeated contract violations.
     /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task Reader_contract_violation_routes_to_onError_callback()
     {
@@ -433,6 +448,7 @@ public sealed class PollGroupEngineTests
     ///     that itself throws — otherwise a buggy health-surface forwarder would crash the poll
     ///     loop and silently stall the subscription, defeating the whole point of the callback.
     /// </summary>
+    /// <returns>A task that represents the asynchronous operation.</returns>
     [Fact]
     public async Task OnError_handler_that_throws_does_not_crash_loop()
     {
@@ -463,7 +479,7 @@ public sealed class PollGroupEngineTests
 
     private sealed record DummyHandle : ISubscriptionHandle
     {
-        /// <summary>Gets a diagnostic identifier for this handle.</summary>
+        /// <inheritdoc />
         public string DiagnosticId => "dummy";
     }