docs: backfill XML documentation across 756 files

Adds <summary>, <param>, <typeparam>, and <inheritdoc/> tags to public
members surfaced by commentchecker — resolves 5,847 of 5,869 issues
(99.6%) across three /fixdocs passes.

tests/Core/ZB.MOM.WW.OtOpcUa.Core.Tests/Resilience/AlarmSurfaceInvokerTests.cs

@@ -10,6 +10,7 @@ public sealed class AlarmSurfaceInvokerTests
 {
     private static readonly DriverResilienceOptions TierAOptions = new() { Tier = DriverTier.A };
 
+    /// <summary>Verifies SubscribeAsync on an empty list returns empty without calling the driver.</summary>
     [Fact]
     public async Task SubscribeAsync_EmptyList_ReturnsEmpty_WithoutDriverCall()
     {
@@ -22,6 +23,7 @@ public sealed class AlarmSurfaceInvokerTests
         driver.SubscribeCallCount.ShouldBe(0);
     }
 
+    /// <summary>Verifies SubscribeAsync with no resolver routes through the default host.</summary>
     [Fact]
     public async Task SubscribeAsync_SingleHost_RoutesThroughDefaultHost()
     {
@@ -35,6 +37,7 @@ public sealed class AlarmSurfaceInvokerTests
         driver.LastSubscribedIds.ShouldBe(["src-1", "src-2"]);
     }
 
+    /// <summary>Verifies SubscribeAsync fans out correctly to multiple hosts based on resolver.</summary>
     [Fact]
     public async Task SubscribeAsync_MultiHost_FansOutByResolvedHost()
     {
@@ -53,6 +56,7 @@ public sealed class AlarmSurfaceInvokerTests
         driver.SubscribeCallCount.ShouldBe(2);     // one driver call per host
     }
 
+    /// <summary>Verifies AcknowledgeAsync does not retry on failure.</summary>
     [Fact]
     public async Task AcknowledgeAsync_DoesNotRetry_OnFailure()
     {
@@ -65,6 +69,7 @@ public sealed class AlarmSurfaceInvokerTests
         driver.AcknowledgeCallCount.ShouldBe(1, "AlarmAcknowledge must not retry — decision #143");
     }
 
+    /// <summary>Verifies SubscribeAsync retries on transient failures.</summary>
     [Fact]
     public async Task SubscribeAsync_Retries_Transient_Failures()
     {
@@ -106,6 +111,7 @@ public sealed class AlarmSurfaceInvokerTests
         driver.UnsubscribeCallCount.ShouldBe(2, "one unsubscribe per subscription handle (per host)");
     }
 
+    /// <summary>Verifies UnsubscribeAsync with no resolver uses the default host.</summary>
     [Fact]
     public async Task UnsubscribeAsync_SingleHost_UsesDefaultHost()
     {
@@ -131,15 +137,31 @@ public sealed class AlarmSurfaceInvokerTests
         return new AlarmSurfaceInvoker(invoker, driver, defaultHost, resolver);
     }
 
+    /// <summary>Fake alarm source for testing.</summary>
     private sealed class FakeAlarmSource : IAlarmSource
     {
+        /// <summary>Gets the number of times SubscribeAlarmsAsync was called.</summary>
         public int SubscribeCallCount { get; private set; }
+
+        /// <summary>Gets the number of times UnsubscribeAlarmsAsync was called.</summary>
         public int UnsubscribeCallCount { get; private set; }
+
+        /// <summary>Gets the number of times AcknowledgeAsync was called.</summary>
         public int AcknowledgeCallCount { get; private set; }
+
+        /// <summary>Gets or sets the number of failures before SubscribeAlarmsAsync succeeds.</summary>
         public int SubscribeFailuresBeforeSuccess { get; set; }
+
+        /// <summary>Gets or sets whether AcknowledgeAsync should throw.</summary>
         public bool AcknowledgeShouldThrow { get; set; }
+
+        /// <summary>Gets the source node IDs from the most recent SubscribeAlarmsAsync call.</summary>
         public IReadOnlyList<string> LastSubscribedIds { get; private set; } = [];
 
+        /// <summary>Subscribes to alarms.</summary>
+        /// <param name="sourceNodeIds">The source node IDs to subscribe to.</param>
+        /// <param name="cancellationToken">Cancellation token.</param>
+        /// <returns>An alarm subscription handle.</returns>
         public Task<IAlarmSubscriptionHandle> SubscribeAlarmsAsync(
             IReadOnlyList<string> sourceNodeIds, CancellationToken cancellationToken)
         {
@@ -150,12 +172,20 @@ public sealed class AlarmSurfaceInvokerTests
             return Task.FromResult<IAlarmSubscriptionHandle>(new StubHandle($"h-{SubscribeCallCount}"));
         }
 
+        /// <summary>Unsubscribes from alarms.</summary>
+        /// <param name="handle">The subscription handle to unsubscribe.</param>
+        /// <param name="cancellationToken">Cancellation token.</param>
+        /// <returns>A completed task.</returns>
         public Task UnsubscribeAlarmsAsync(IAlarmSubscriptionHandle handle, CancellationToken cancellationToken)
         {
             UnsubscribeCallCount++;
             return Task.CompletedTask;
         }
 
+        /// <summary>Acknowledges alarms.</summary>
+        /// <param name="acknowledgements">The alarm acknowledgements to process.</param>
+        /// <param name="cancellationToken">Cancellation token.</param>
+        /// <returns>A completed task.</returns>
         public Task AcknowledgeAsync(
             IReadOnlyList<AlarmAcknowledgeRequest> acknowledgements, CancellationToken cancellationToken)
         {
@@ -164,13 +194,21 @@ public sealed class AlarmSurfaceInvokerTests
             return Task.CompletedTask;
         }
 
+        /// <summary>Occurs when an alarm event is raised.</summary>
         public event EventHandler<AlarmEventArgs>? OnAlarmEvent { add { } remove { } }
     }
 
+    /// <summary>Stub alarm subscription handle for testing.</summary>
+    /// <param name="DiagnosticId">Diagnostic identifier for the handle.</param>
     private sealed record StubHandle(string DiagnosticId) : IAlarmSubscriptionHandle;
 
+    /// <summary>Stub host resolver for testing multi-host scenarios.</summary>
+    /// <param name="map">The map of source node IDs to host names.</param>
     private sealed class StubResolver(Dictionary<string, string> map) : IPerCallHostResolver
     {
+        /// <summary>Resolves the host for the given full reference.</summary>
+        /// <param name="fullReference">The full reference to resolve.</param>
+        /// <returns>The resolved host name.</returns>
         public string ResolveHost(string fullReference) => map[fullReference];
     }
 }

tests/Core/ZB.MOM.WW.OtOpcUa.Core.Tests/Resilience/CapabilityInvokerTests.cs

@@ -13,6 +13,7 @@ public sealed class CapabilityInvokerTests
         DriverResilienceOptions options) =>
         new(builder, "drv-test", () => options);
 
+    /// <summary>Verifies that the capability invoker returns the value from the call site.</summary>
     [Fact]
     public async Task Read_ReturnsValue_FromCallSite()
     {
@@ -27,6 +28,7 @@ public sealed class CapabilityInvokerTests
         result.ShouldBe(42);
     }
 
+    /// <summary>Verifies that the capability invoker retries on transient failures.</summary>
     [Fact]
     public async Task Read_Retries_OnTransientFailure()
     {
@@ -49,6 +51,7 @@ public sealed class CapabilityInvokerTests
         attempts.ShouldBe(2);
     }
 
+    /// <summary>Verifies that non-idempotent writes do not retry even when the policy has retries configured.</summary>
     [Fact]
     public async Task Write_NonIdempotent_DoesNotRetry_EvenWhenPolicyHasRetries()
     {
@@ -81,6 +84,7 @@ public sealed class CapabilityInvokerTests
         attempts.ShouldBe(1, "non-idempotent write must never replay");
     }
 
+    /// <summary>Verifies that idempotent writes retry when the policy has retries configured.</summary>
     [Fact]
     public async Task Write_Idempotent_Retries_WhenPolicyHasRetries()
     {
@@ -111,6 +115,7 @@ public sealed class CapabilityInvokerTests
         attempts.ShouldBe(2);
     }
 
+    /// <summary>Verifies that writes do not retry when the policy has zero retries configured.</summary>
     [Fact]
     public async Task Write_Default_DoesNotRetry_WhenPolicyHasZeroRetries()
     {
@@ -137,6 +142,7 @@ public sealed class CapabilityInvokerTests
         attempts.ShouldBe(1, "tier-A default for Write is RetryCount=0");
     }
 
+    /// <summary>Verifies that different hosts are honored independently in the resilience pipeline.</summary>
     [Fact]
     public async Task Execute_HonorsDifferentHosts_Independently()
     {

tests/Core/ZB.MOM.WW.OtOpcUa.Core.Tests/Resilience/DriverResilienceOptionsParserTests.cs

@@ -8,6 +8,7 @@ namespace ZB.MOM.WW.OtOpcUa.Core.Tests.Resilience;
 [Trait("Category", "Unit")]
 public sealed class DriverResilienceOptionsParserTests
 {
+    /// <summary>Verifies that null JSON returns pure tier defaults.</summary>
     [Fact]
     public void NullJson_ReturnsPureTierDefaults()
     {
@@ -19,6 +20,7 @@ public sealed class DriverResilienceOptionsParserTests
             DriverResilienceOptions.GetTierDefaults(DriverTier.A)[DriverCapability.Read]);
     }
 
+    /// <summary>Verifies that whitespace JSON returns defaults.</summary>
     [Fact]
     public void WhitespaceJson_ReturnsDefaults()
     {
@@ -26,6 +28,7 @@ public sealed class DriverResilienceOptionsParserTests
         diag.ShouldBeNull();
     }
 
+    /// <summary>Verifies that malformed JSON falls back with diagnostic.</summary>
     [Fact]
     public void MalformedJson_FallsBack_WithDiagnostic()
     {
@@ -38,6 +41,7 @@ public sealed class DriverResilienceOptionsParserTests
             DriverResilienceOptions.GetTierDefaults(DriverTier.A)[DriverCapability.Read]);
     }
 
+    /// <summary>Verifies that empty object returns defaults.</summary>
     [Fact]
     public void EmptyObject_ReturnsDefaults()
     {
@@ -48,6 +52,7 @@ public sealed class DriverResilienceOptionsParserTests
             DriverResilienceOptions.GetTierDefaults(DriverTier.A)[DriverCapability.Write]);
     }
 
+    /// <summary>Verifies that Read override is merged into tier defaults.</summary>
     [Fact]
     public void ReadOverride_MergedIntoTierDefaults()
     {
@@ -72,6 +77,7 @@ public sealed class DriverResilienceOptionsParserTests
             DriverResilienceOptions.GetTierDefaults(DriverTier.A)[DriverCapability.Write]);
     }
 
+    /// <summary>Verifies that partial policy fills missing fields from tier default.</summary>
     [Fact]
     public void PartialPolicy_FillsMissingFieldsFromTierDefault()
     {
@@ -92,6 +98,7 @@ public sealed class DriverResilienceOptionsParserTests
         read.BreakerFailureThreshold.ShouldBe(tierDefault.BreakerFailureThreshold);
     }
 
+    /// <summary>Verifies that bulkhead overrides are honored.</summary>
     [Fact]
     public void BulkheadOverrides_AreHonored()
     {
@@ -105,6 +112,7 @@ public sealed class DriverResilienceOptionsParserTests
         options.BulkheadMaxQueue.ShouldBe(500);
     }
 
+    /// <summary>Verifies that unknown capability surfaces in diagnostic but does not fail.</summary>
     [Fact]
     public void UnknownCapability_Surfaces_InDiagnostic_ButDoesNotFail()
     {
@@ -125,6 +133,7 @@ public sealed class DriverResilienceOptionsParserTests
             DriverResilienceOptions.GetTierDefaults(DriverTier.A)[DriverCapability.Read]);
     }
 
+    /// <summary>Verifies that property names are case insensitive.</summary>
     [Fact]
     public void PropertyNames_AreCaseInsensitive()
     {
@@ -137,6 +146,7 @@ public sealed class DriverResilienceOptionsParserTests
         options.BulkheadMaxConcurrent.ShouldBe(42);
     }
 
+    /// <summary>Verifies that capability name is case insensitive.</summary>
     [Fact]
     public void CapabilityName_IsCaseInsensitive()
     {
@@ -150,6 +160,8 @@ public sealed class DriverResilienceOptionsParserTests
         options.Resolve(DriverCapability.Read).RetryCount.ShouldBe(99);
     }
 
+    /// <summary>Verifies that every tier with empty JSON round-trips its defaults.</summary>
+    /// <param name="tier">The driver tier to test.</param>
     [Theory]
     [InlineData(DriverTier.A)]
     [InlineData(DriverTier.B)]
@@ -164,6 +176,7 @@ public sealed class DriverResilienceOptionsParserTests
             options.Resolve(cap).ShouldBe(DriverResilienceOptions.GetTierDefaults(tier)[cap]);
     }
 
+    /// <summary>Verifies that RecycleIntervalSeconds on Tier C with positive value parses and surfaces.</summary>
     [Fact]
     public void RecycleIntervalSeconds_TierC_PositiveValue_ParsesAndSurfaces()
     {
@@ -174,6 +187,7 @@ public sealed class DriverResilienceOptionsParserTests
         options.RecycleIntervalSeconds.ShouldBe(3600);
     }
 
+    /// <summary>Verifies that RecycleIntervalSeconds when null defaults to null.</summary>
     [Fact]
     public void RecycleIntervalSeconds_Null_DefaultsToNull()
     {
@@ -181,6 +195,8 @@ public sealed class DriverResilienceOptionsParserTests
         options.RecycleIntervalSeconds.ShouldBeNull();
     }
 
+    /// <summary>Verifies that RecycleIntervalSeconds on Tier A or B is rejected with diagnostic.</summary>
+    /// <param name="tier">The driver tier to test.</param>
     [Theory]
     [InlineData(DriverTier.A)]
     [InlineData(DriverTier.B)]
@@ -196,6 +212,7 @@ public sealed class DriverResilienceOptionsParserTests
         diag.ShouldContain("Tier C only");
     }
 
+    /// <summary>Verifies that RecycleIntervalSeconds with non-positive value is rejected with diagnostic.</summary>
     [Fact]
     public void RecycleIntervalSeconds_NonPositive_Rejected_With_Diagnostic()
     {

tests/Core/ZB.MOM.WW.OtOpcUa.Core.Tests/Resilience/DriverResilienceOptionsTests.cs

@@ -8,6 +8,8 @@ namespace ZB.MOM.WW.OtOpcUa.Core.Tests.Resilience;
 [Trait("Category", "Unit")]
 public sealed class DriverResilienceOptionsTests
 {
+    /// <summary>Verifies that tier defaults cover every capability.</summary>
+    /// <param name="tier">The driver tier to test.</param>
     [Theory]
     [InlineData(DriverTier.A)]
     [InlineData(DriverTier.B)]
@@ -20,6 +22,8 @@ public sealed class DriverResilienceOptionsTests
             defaults.ShouldContainKey(capability);
     }
 
+    /// <summary>Verifies that write never retries by default.</summary>
+    /// <param name="tier">The driver tier to test.</param>
     [Theory]
     [InlineData(DriverTier.A)]
     [InlineData(DriverTier.B)]
@@ -30,6 +34,8 @@ public sealed class DriverResilienceOptionsTests
         defaults[DriverCapability.Write].RetryCount.ShouldBe(0);
     }
 
+    /// <summary>Verifies that alarm acknowledge never retries by default.</summary>
+    /// <param name="tier">The driver tier to test.</param>
     [Theory]
     [InlineData(DriverTier.A)]
     [InlineData(DriverTier.B)]
@@ -40,6 +46,9 @@ public sealed class DriverResilienceOptionsTests
         defaults[DriverCapability.AlarmAcknowledge].RetryCount.ShouldBe(0);
     }
 
+    /// <summary>Verifies that idempotent capabilities retry by default.</summary>
+    /// <param name="tier">The driver tier to test.</param>
+    /// <param name="capability">The driver capability to test.</param>
     [Theory]
     [InlineData(DriverTier.A, DriverCapability.Read)]
     [InlineData(DriverTier.A, DriverCapability.HistoryRead)]
@@ -52,6 +61,7 @@ public sealed class DriverResilienceOptionsTests
         defaults[capability].RetryCount.ShouldBeGreaterThan(0);
     }
 
+    /// <summary>Verifies that TierC disables circuit breaker deferring to supervisor.</summary>
     [Fact]
     public void TierC_DisablesCircuitBreaker_DeferringToSupervisor()
     {
@@ -61,6 +71,8 @@ public sealed class DriverResilienceOptionsTests
             policy.BreakerFailureThreshold.ShouldBe(0, "Tier C breaker is handled by the Proxy supervisor (decision #68)");
     }
 
+    /// <summary>Verifies that TierA and TierB enable circuit breaker.</summary>
+    /// <param name="tier">The driver tier to test.</param>
     [Theory]
     [InlineData(DriverTier.A)]
     [InlineData(DriverTier.B)]
@@ -72,6 +84,7 @@ public sealed class DriverResilienceOptionsTests
             policy.BreakerFailureThreshold.ShouldBeGreaterThan(0);
     }
 
+    /// <summary>Verifies that resolve uses tier defaults when no override is set.</summary>
     [Fact]
     public void Resolve_Uses_TierDefaults_When_NoOverride()
     {
@@ -82,6 +95,7 @@ public sealed class DriverResilienceOptionsTests
         resolved.ShouldBe(DriverResilienceOptions.GetTierDefaults(DriverTier.A)[DriverCapability.Read]);
     }
 
+    /// <summary>Verifies that resolve uses override when configured.</summary>
     [Fact]
     public void Resolve_Uses_Override_When_Configured()
     {
@@ -106,6 +120,7 @@ public sealed class DriverResilienceOptionsTests
     ///     enum-only addition that forgets to update <c>GetTierDefaults</c> would otherwise blow up
     ///     on the hot path with <see cref="KeyNotFoundException"/>.
     /// </summary>
+    /// <param name="tier">The driver tier to test.</param>
     [Theory]
     [InlineData(DriverTier.A)]
     [InlineData(DriverTier.B)]

tests/Core/ZB.MOM.WW.OtOpcUa.Core.Tests/Resilience/DriverResiliencePipelineBuilderTests.cs

@@ -12,6 +12,7 @@ public sealed class DriverResiliencePipelineBuilderTests
 {
     private static readonly DriverResilienceOptions TierAOptions = new() { Tier = DriverTier.A };
 
+    /// <summary>Verifies that read operations retry transient failures.</summary>
     [Fact]
     public async Task Read_Retries_Transient_Failures()
     {
@@ -29,6 +30,7 @@ public sealed class DriverResiliencePipelineBuilderTests
         attempts.ShouldBe(3);
     }
 
+    /// <summary>Verifies that write operations do not retry on failure.</summary>
     [Fact]
     public async Task Write_DoesNotRetry_OnFailure()
     {
@@ -50,6 +52,7 @@ public sealed class DriverResiliencePipelineBuilderTests
         ex.Message.ShouldBe("boom");
     }
 
+    /// <summary>Verifies that alarm acknowledge operations do not retry on failure.</summary>
     [Fact]
     public async Task AlarmAcknowledge_DoesNotRetry_OnFailure()
     {
@@ -70,6 +73,7 @@ public sealed class DriverResiliencePipelineBuilderTests
         attempts.ShouldBe(1);
     }
 
+    /// <summary>Verifies that pipelines are isolated per host.</summary>
     [Fact]
     public void Pipeline_IsIsolated_PerHost()
     {
@@ -83,6 +87,7 @@ public sealed class DriverResiliencePipelineBuilderTests
         builder.CachedPipelineCount.ShouldBe(2);
     }
 
+    /// <summary>Verifies that pipelines are reused for the same driver, host, and capability triple.</summary>
     [Fact]
     public void Pipeline_IsReused_ForSameTriple()
     {
@@ -96,6 +101,7 @@ public sealed class DriverResiliencePipelineBuilderTests
         builder.CachedPipelineCount.ShouldBe(1);
     }
 
+    /// <summary>Verifies that pipelines are isolated per capability.</summary>
     [Fact]
     public void Pipeline_IsIsolated_PerCapability()
     {
@@ -108,6 +114,7 @@ public sealed class DriverResiliencePipelineBuilderTests
         read.ShouldNotBeSameAs(write);
     }
 
+    /// <summary>Verifies that a dead host does not open the breaker for a sibling host.</summary>
     [Fact]
     public async Task DeadHost_DoesNotOpenBreaker_ForSiblingHost()
     {
@@ -138,6 +145,7 @@ public sealed class DriverResiliencePipelineBuilderTests
         liveAttempts.ShouldBe(1, "healthy sibling host must not be affected by dead peer");
     }
 
+    /// <summary>Verifies that the circuit breaker opens after the failure threshold on tier A.</summary>
     [Fact]
     public async Task CircuitBreaker_Opens_AfterFailureThreshold_OnTierA()
     {
@@ -162,6 +170,7 @@ public sealed class DriverResiliencePipelineBuilderTests
             }));
     }
 
+    /// <summary>Verifies that timeout cancels slow operations.</summary>
     [Fact]
     public async Task Timeout_Cancels_SlowOperation()
     {
@@ -183,6 +192,7 @@ public sealed class DriverResiliencePipelineBuilderTests
             }));
     }
 
+    /// <summary>Verifies that invalidate removes only the matching instance.</summary>
     [Fact]
     public void Invalidate_Removes_OnlyMatchingInstance()
     {
@@ -200,6 +210,7 @@ public sealed class DriverResiliencePipelineBuilderTests
         builder.CachedPipelineCount.ShouldBe(2);
     }
 
+    /// <summary>Verifies that cancellation is not retried.</summary>
     [Fact]
     public async Task Cancellation_IsNot_Retried()
     {
@@ -220,6 +231,7 @@ public sealed class DriverResiliencePipelineBuilderTests
         attempts.ShouldBeLessThanOrEqualTo(1);
     }
 
+    /// <summary>Verifies that the tracker records failure on every retry.</summary>
     [Fact]
     public async Task Tracker_RecordsFailure_OnEveryRetry()
     {
@@ -240,6 +252,7 @@ public sealed class DriverResiliencePipelineBuilderTests
         snap!.ConsecutiveFailures.ShouldBe(retryCount);
     }
 
+    /// <summary>Verifies that the tracker stamps the breaker open when it trips.</summary>
     [Fact]
     public async Task Tracker_StampsBreakerOpen_WhenBreakerTrips()
     {
@@ -263,6 +276,7 @@ public sealed class DriverResiliencePipelineBuilderTests
         snap!.LastBreakerOpenUtc.ShouldNotBeNull();
     }
 
+    /// <summary>Verifies that the tracker isolates counters per host.</summary>
     [Fact]
     public async Task Tracker_IsolatesCounters_PerHost()
     {

tests/Core/ZB.MOM.WW.OtOpcUa.Core.Tests/Resilience/DriverResilienceStatusTrackerTests.cs

@@ -9,6 +9,7 @@ public sealed class DriverResilienceStatusTrackerTests
 {
     private static readonly DateTime Now = new(2026, 4, 19, 12, 0, 0, DateTimeKind.Utc);
 
+    /// <summary>Verifies that TryGet returns null before any write operations.</summary>
     [Fact]
     public void TryGet_Returns_Null_Before_AnyWrite()
     {
@@ -17,6 +18,7 @@ public sealed class DriverResilienceStatusTrackerTests
         tracker.TryGet("drv", "host").ShouldBeNull();
     }
 
+    /// <summary>Verifies that RecordFailure accumulates consecutive failures.</summary>
     [Fact]
     public void RecordFailure_Accumulates_ConsecutiveFailures()
     {
@@ -29,6 +31,7 @@ public sealed class DriverResilienceStatusTrackerTests
         tracker.TryGet("drv", "host")!.ConsecutiveFailures.ShouldBe(3);
     }
 
+    /// <summary>Verifies that RecordSuccess resets consecutive failures to zero.</summary>
     [Fact]
     public void RecordSuccess_Resets_ConsecutiveFailures()
     {
@@ -41,6 +44,7 @@ public sealed class DriverResilienceStatusTrackerTests
         tracker.TryGet("drv", "host")!.ConsecutiveFailures.ShouldBe(0);
     }
 
+    /// <summary>Verifies that RecordBreakerOpen populates the LastBreakerOpenUtc timestamp.</summary>
     [Fact]
     public void RecordBreakerOpen_Populates_LastBreakerOpenUtc()
     {
@@ -51,6 +55,7 @@ public sealed class DriverResilienceStatusTrackerTests
         tracker.TryGet("drv", "host")!.LastBreakerOpenUtc.ShouldBe(Now);
     }
 
+    /// <summary>Verifies that RecordRecycle populates the LastRecycleUtc timestamp.</summary>
     [Fact]
     public void RecordRecycle_Populates_LastRecycleUtc()
     {
@@ -61,6 +66,7 @@ public sealed class DriverResilienceStatusTrackerTests
         tracker.TryGet("drv", "host")!.LastRecycleUtc.ShouldBe(Now);
     }
 
+    /// <summary>Verifies that RecordFootprint captures baseline and current memory usage.</summary>
     [Fact]
     public void RecordFootprint_CapturesBaselineAndCurrent()
     {
@@ -73,6 +79,7 @@ public sealed class DriverResilienceStatusTrackerTests
         snap.CurrentFootprintBytes.ShouldBe(150_000_000);
     }
 
+    /// <summary>Verifies that different hosts are tracked independently.</summary>
     [Fact]
     public void DifferentHosts_AreIndependent()
     {
@@ -86,6 +93,7 @@ public sealed class DriverResilienceStatusTrackerTests
         tracker.TryGet("drv", "host-b")!.ConsecutiveFailures.ShouldBe(1);
     }
 
+    /// <summary>Verifies that Snapshot returns all tracked driver-host pairs.</summary>
     [Fact]
     public void Snapshot_ReturnsAll_TrackedPairs()
     {
@@ -99,6 +107,7 @@ public sealed class DriverResilienceStatusTrackerTests
         snapshot.Count.ShouldBe(3);
     }
 
+    /// <summary>Verifies that concurrent writes do not lose failure records.</summary>
     [Fact]
     public void ConcurrentWrites_DoNotLose_Failures()
     {

tests/Core/ZB.MOM.WW.OtOpcUa.Core.Tests/Resilience/FlakeyDriverIntegrationTests.cs

@@ -14,6 +14,7 @@ namespace ZB.MOM.WW.OtOpcUa.Core.Tests.Resilience;
 [Trait("Category", "Integration")]
 public sealed class FlakeyDriverIntegrationTests
 {
+    /// <summary>Verifies read succeeds after transient failures with retries.</summary>
     [Fact]
     public async Task Read_SurfacesSuccess_AfterTransientFailures()
     {
@@ -41,6 +42,7 @@ public sealed class FlakeyDriverIntegrationTests
         result[0].StatusCode.ShouldBe(0u);
     }
 
+    /// <summary>Verifies non-idempotent write fails on first failure without replay.</summary>
     [Fact]
     public async Task Write_NonIdempotent_FailsOnFirstFailure_NoReplay()
     {
@@ -65,6 +67,7 @@ public sealed class FlakeyDriverIntegrationTests
         flaky.WriteAttempts.ShouldBe(1, "non-idempotent write must never replay (decision #44)");
     }
 
+    /// <summary>Verifies idempotent write retries until success.</summary>
     [Fact]
     public async Task Write_Idempotent_RetriesUntilSuccess()
     {
@@ -89,6 +92,7 @@ public sealed class FlakeyDriverIntegrationTests
         results[0].StatusCode.ShouldBe(0u);
     }
 
+    /// <summary>Verifies multiple hosts have independent failure counts and circuit breakers.</summary>
     [Fact]
     public async Task MultipleHosts_OnOneDriver_HaveIndependentFailureCounts()
     {
@@ -116,20 +120,31 @@ public sealed class FlakeyDriverIntegrationTests
         liveAttempts.ShouldBe(1);
     }
 
+    /// <summary>Driver that fails reads/writes for a configurable number of attempts.</summary>
     private sealed class FlakeyDriver : IReadable, IWritable
     {
         private readonly int _failReadsBeforeIndex;
         private readonly int _failWritesBeforeIndex;
 
+        /// <summary>Gets the number of read attempts made.</summary>
         public int ReadAttempts { get; private set; }
+
+        /// <summary>Gets the number of write attempts made.</summary>
         public int WriteAttempts { get; private set; }
 
+        /// <summary>Initializes a flaky driver with configurable failure counts.</summary>
+        /// <param name="failReadsBeforeIndex">Fail reads until this attempt number.</param>
+        /// <param name="failWritesBeforeIndex">Fail writes until this attempt number.</param>
         public FlakeyDriver(int failReadsBeforeIndex = 0, int failWritesBeforeIndex = 0)
         {
             _failReadsBeforeIndex = failReadsBeforeIndex;
             _failWritesBeforeIndex = failWritesBeforeIndex;
         }
 
+        /// <summary>Reads values, failing transiently until the threshold.</summary>
+        /// <param name="fullReferences">Full references to read.</param>
+        /// <param name="cancellationToken">Cancellation token.</param>
+        /// <returns>Data value snapshots.</returns>
         public Task<IReadOnlyList<DataValueSnapshot>> ReadAsync(
             IReadOnlyList<string> fullReferences,
             CancellationToken cancellationToken)
@@ -145,6 +160,10 @@ public sealed class FlakeyDriverIntegrationTests
             return Task.FromResult(result);
         }
 
+        /// <summary>Writes values, failing transiently until the threshold.</summary>
+        /// <param name="writes">The write requests.</param>
+        /// <param name="cancellationToken">Cancellation token.</param>
+        /// <returns>Write results.</returns>
         public Task<IReadOnlyList<WriteResult>> WriteAsync(
             IReadOnlyList<WriteRequest> writes,
             CancellationToken cancellationToken)

tests/Core/ZB.MOM.WW.OtOpcUa.Core.Tests/Resilience/InFlightCounterTests.cs

@@ -8,6 +8,7 @@ namespace ZB.MOM.WW.OtOpcUa.Core.Tests.Resilience;
 [Trait("Category", "Unit")]
 public sealed class InFlightCounterTests
 {
+    /// <summary>Verifies that starting and completing a call nets to zero.</summary>
     [Fact]
     public void StartThenComplete_NetsToZero()
     {
@@ -18,6 +19,7 @@ public sealed class InFlightCounterTests
         tracker.TryGet("drv", "host-a")!.CurrentInFlight.ShouldBe(0);
     }
 
+    /// <summary>Verifies that nested starts sum the depth.</summary>
     [Fact]
     public void NestedStarts_SumDepth()
     {
@@ -32,6 +34,7 @@ public sealed class InFlightCounterTests
         tracker.TryGet("drv", "host-a")!.CurrentInFlight.ShouldBe(2);
     }
 
+    /// <summary>Verifies that completing before start is clamped to zero.</summary>
     [Fact]
     public void CompleteBeforeStart_ClampedToZero()
     {
@@ -42,6 +45,7 @@ public sealed class InFlightCounterTests
         tracker.TryGet("drv", "host-a")!.CurrentInFlight.ShouldBe(0);
     }
 
+    /// <summary>Verifies that different hosts track independently.</summary>
     [Fact]
     public void DifferentHosts_TrackIndependently()
     {
@@ -54,6 +58,7 @@ public sealed class InFlightCounterTests
         tracker.TryGet("drv", "host-b")!.CurrentInFlight.ShouldBe(1);
     }
 
+    /// <summary>Verifies that concurrent starts do not lose count.</summary>
     [Fact]
     public void ConcurrentStarts_DoNotLose_Count()
     {
@@ -63,6 +68,7 @@ public sealed class InFlightCounterTests
         tracker.TryGet("drv", "host-a")!.CurrentInFlight.ShouldBe(500);
     }
 
+    /// <summary>Verifies that CapabilityInvoker increments the tracker during execution.</summary>
     [Fact]
     public async Task CapabilityInvoker_IncrementsTracker_DuringExecution()
     {
@@ -90,6 +96,7 @@ public sealed class InFlightCounterTests
         tracker.TryGet("drv-live", "plc-1")!.CurrentInFlight.ShouldBe(0, "post-call, counter decremented");
     }
 
+    /// <summary>Verifies that CapabilityInvoker decrements the counter on exception.</summary>
     [Fact]
     public async Task CapabilityInvoker_ExceptionPath_DecrementsCounter()
     {
@@ -111,6 +118,7 @@ public sealed class InFlightCounterTests
             "finally-block must decrement even when call-site throws");
     }
 
+    /// <summary>Verifies that CapabilityInvoker without a tracker does not throw.</summary>
     [Fact]
     public async Task CapabilityInvoker_WithoutTracker_DoesNotThrow()
     {

tests/Core/ZB.MOM.WW.OtOpcUa.Core.Tests/Resilience/PerCallHostResolverDispatchTests.cs

@@ -17,11 +17,18 @@ public sealed class PerCallHostResolverDispatchTests
     private sealed class StaticResolver : IPerCallHostResolver
     {
         private readonly Dictionary<string, string> _map;
+
+        /// <summary>Initializes a new instance of StaticResolver with a predefined mapping.</summary>
+        /// <param name="map">The mapping of full references to host names.</param>
         public StaticResolver(Dictionary<string, string> map) => _map = map;
+
+        /// <summary>Resolves a host name from the static mapping.</summary>
+        /// <param name="fullReference">The full reference to resolve.</param>
         public string ResolveHost(string fullReference) =>
             _map.TryGetValue(fullReference, out var host) ? host : string.Empty;
     }
 
+    /// <summary>Verifies that a dead PLC does not open the breaker for healthy PLCs when using a per-call resolver.</summary>
     [Fact]
     public async Task DeadPlc_DoesNotOpenBreaker_For_HealthyPlc_With_Resolver()
     {
@@ -59,6 +66,7 @@ public sealed class PerCallHostResolverDispatchTests
         aliveAttempts.ShouldBe(1, "decision #144 — per-PLC isolation keeps healthy PLCs serving");
     }
 
+    /// <summary>Verifies that empty string from resolver is treated as single-host fallback.</summary>
     [Fact]
     public void Resolver_EmptyString_Treated_As_Single_Host_Fallback()
     {
@@ -71,6 +79,7 @@ public sealed class PerCallHostResolverDispatchTests
         resolver.ResolveHost("not-in-map").ShouldBe("", "unknown refs return empty so dispatch falls back to single-host");
     }
 
+    /// <summary>Verifies that without a resolver, the same host shares one resilience pipeline.</summary>
     [Fact]
     public async Task WithoutResolver_SameHost_Shares_One_Pipeline()
     {
@@ -88,6 +97,7 @@ public sealed class PerCallHostResolverDispatchTests
         builder.CachedPipelineCount.ShouldBe(1, "single-host drivers share one pipeline");
     }
 
+    /// <summary>Verifies that with a resolver, different hosts get separate resilience pipelines.</summary>
     [Fact]
     public async Task WithResolver_TwoHosts_Get_Two_Pipelines()
     {