diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/Compatibility/Aggregates/README.md b/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/Compatibility/Aggregates/README.md
index ffb5e45b..3f1ddc0b 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/Compatibility/Aggregates/README.md
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/Compatibility/Aggregates/README.md
@@ -10,9 +10,9 @@ Representation adaptations:
 - Nullable reference annotations describe the existing optional bounds/slices; no warning policy is disabled.
 - Immutable StatusCode methods replace the old setters. NodeId extraction and QualifiedName construction use supported typed APIs.
 - Removed TypeInfo.Cast/Variant(object, TypeInfo) operations use the SDK 2 typed conversion surface; baseline vectors verify value **types**, values, timestamps and all status bits.
-- Interval, quality, sample selection, queue trimming, interpolation and partial-result algorithms remain the baseline algorithms. Factory registration replaces the existing 37 IDs through the public SDK API; it must not add capabilities or duplicate advertised references.
+- Interval, quality, sample selection, queue trimming, interpolation and partial-result algorithms remain the baseline algorithms. The server creates a fresh SDK AggregateManager and registers these 37 IDs exactly once through the public API. It must not call the base registration first: replacing an existing factory also adds a duplicate diagnostic node in SDK 2.0.1. No extra capability is advertised.
 
-The isolated `scripts/validation/opcua-aggregate-baseline` process pins only SDK 1.5.378.182 and generates the checked-in golden fixture. It is deliberately outside the solution and does not inherit the candidate package graph. The golden file records the baseline assembly hash, shared inputs and 4,144 outputs/cases across all 37 aggregate IDs, seven datasets, forward/reverse, stepped/sloped interpolation, uncertain-as-bad flags and incremental/partial processing. No baseline binary is loaded by the candidate tests or production host.
+The isolated `scripts/validation/opcua-aggregate-baseline` process pins only SDK 1.5.378.182 and generates the checked-in golden fixture. It is deliberately outside the solution and does not inherit the candidate package graph. The golden file records the baseline assembly hash, shared inputs and 6,144 outputs/cases across all 37 aggregate IDs: the original 4,144 cases plus 2,000 numeric-width, nonfinite/conversion, timestamp tie/picosecond and configuration-edge cases. Forward/reverse, stepped/sloped interpolation, uncertain-as-bad flags and incremental/partial processing are retained. The candidate tests exercise the same independent expectations both directly and through the booted runtime manager. Unset SDK 2 FILETIME timestamps map explicitly to the original CLR unset sentinel when observing results. No baseline binary is loaded by the candidate tests or production host.
 
 Run the generator with a **new** output path, then compare it with `tests/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer.IntegrationTests/Fixtures/opcua-1.5.378.182-aggregates.json`. It refuses to overwrite evidence. Never regenerate expectations from the compatibility implementation. Existing historian parity tests retain their application-specific documented divergences from the baseline SDK, while new compatibility tests check the complete old-calculator output.
 
diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OpcUaApplicationHost.cs b/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OpcUaApplicationHost.cs
index e6fa9067..b383df19 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OpcUaApplicationHost.cs
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/OpcUaApplicationHost.cs
@@ -161,8 +161,8 @@ public sealed class OpcUaQuotaOptions
 /// Thin facade over the OPC Foundation .NET Standard SDK's application bootstrap.
 /// Owns the <see cref="ApplicationInstance"/> + <see cref="ApplicationConfiguration"/> lifetime,
 /// builds the <see cref="ApplicationConfiguration"/> programmatically (security profiles + user
-/// token policies + PKI stores), starts a <see cref="StandardServer"/>, attaches the
-/// <c>ImpersonateUser</c> hook for UserName-token authentication via
+/// token policies + PKI stores), installs an SDK identity-registry authenticator before
+/// the <see cref="OtOpcUaSdkServer"/> opens its listeners via
 /// <see cref="IOpcUaUserAuthenticator"/>, and publishes the redundancy peer URIs through
 /// <c>Server.ServerArray</c>. See <c>docs/OpcUaServer.md</c> and <c>docs/security.md</c>.
 /// </summary>
@@ -468,7 +468,7 @@ public sealed class OpcUaApplicationHost : IAsyncDisposable
     private async Task EnsureApplicationCertificateAsync(CancellationToken cancellationToken)
     {
         // silent: false → SDK logs cert creation events through its own trace plumbing.
-        // minimumKeySize/lifetimeInMonths: 0 → use SDK defaults (2048-bit, 12-month lifetime).
+        // A null lifetime keeps the SDK default (12 months). Key-size policy comes from the configuration.
         var ok = await _application!.CheckApplicationInstanceCertificatesAsync(
             false, null, cancellationToken).ConfigureAwait(false);
         if (!ok)
@@ -610,10 +610,10 @@ public sealed class OpcUaApplicationHost : IAsyncDisposable
     /// <summary>
     /// Anonymous + UserName token policies. UserName tokens are always SDK-encrypted with
     /// the server certificate (see docs/security.md "UserName token encryption") so the
-    /// policy works on None endpoints too. The real LDAP-bound validator is wired through
-    /// <see cref="IOpcUaUserAuthenticator"/> on <c>StandardServer.SessionManager.ImpersonateUser</c>
-    /// (see <see cref="AttachUserAuthenticator"/> / <see cref="HandleImpersonation"/>); the Host
-    /// project supplies the LDAP adapter, and <see cref="NullOpcUaUserAuthenticator"/> denies all
+    /// policy works on None endpoints too. The Host supplies API-key authentication through
+    /// <see cref="IOpcUaUserAuthenticator"/>; <see cref="AttachUserAuthenticator"/> installs it in the
+    /// SDK identity registry before listeners open. <see cref="HandleImpersonation"/> retains the
+    /// application decision seam, and <see cref="NullOpcUaUserAuthenticator"/> denies all
     /// UserName logins when none is registered.
     /// </summary>
     /// <param name="allowAnonymous">Whether the Anonymous policy is advertised.</param>
diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/Security/RoleCarryingUserIdentity.cs b/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/Security/RoleCarryingUserIdentity.cs
index 96de455e..f4a26366 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/Security/RoleCarryingUserIdentity.cs
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.OpcUaServer/Security/RoleCarryingUserIdentity.cs
@@ -4,7 +4,7 @@ using Opc.Ua.Server;
 namespace ZB.MOM.WW.OtOpcUa.OpcUaServer.Security;
 
 /// <summary>
-/// A <see cref="UserIdentity"/> that additionally carries the LDAP-resolved roles
+/// An SDK identity that additionally carries the application roles resolved for an API key
 /// (<see cref="OpcUaUserAuthResult.Roles"/>) for the authenticated session. The SDK may augment identities with mandatory and dynamically mapped roles. This subtype
 /// preserves the application identity when those roles are added, so a method
 /// handler can later recover the roles via