fix: resolve code-review findings (locally verified)

Server-054/055/056, Contracts-020/021/022, Tests-036/038/039,
IntegrationTests-030/031/032 (+033 deferred to live rig),
Client.Dotnet-026/028/029 (+027 won't-fix), Client.Go-030..034,
Client.Python-032..036, Client.Rust-033..038.

Key fix: SessionEventDistributor orphaned a subscriber that registered after
the pump completed but before disposal (Server-056) -> register paths now
complete late registrants under _lifecycleLock; regression test added. The
racy dashboard-mirror gRPC test made deterministic (Tests-039).

Verified green locally: gateway Tests targeted classes (GatewaySession,
SessionEventDistributor, GatewayOptionsValidator, ProtobufContractRoundTrip,
GatewaySessionDashboardMirror) + dotnet/go/python/rust client suites.

code-reviews/IntegrationTests/findings.md

@@ -7,7 +7,7 @@
 | Review date | 2026-06-16 |
 | Commit reviewed | `8df5ab3` |
 | Status | Re-reviewed |
-| Open findings | 4 |
+| Open findings | 0 |
 
 ## Checklist coverage
 
@@ -633,13 +633,13 @@ The prior `DashboardAuthenticator` ctor took `IOptions<GatewayOptions>`, so the
 | Severity | Low |
 | Category | Documentation & comments |
 | Location | `docs/GatewayTesting.md:76`, `src/ZB.MOM.WW.MxGateway.IntegrationTests/WorkerLiveMxAccessSmokeTests.cs:576,728` |
-| Status | Open |
+| Status | Resolved |
 
 **Description:** `docs/GatewayTesting.md` says "All six tests are gated by MXGATEWAY_RUN_LIVE_MXACCESS_TESTS=1" and enumerates five parity paths. This diff adds two new `[LiveMxAccessFact]` tests (B8 new COM commands: AuthenticateUser/ArchestrAUserToId/Suspend/Activate; and the buffered-data path: AddBufferedItem/SetBufferedUpdateInterval), bringing the total to eight. The doc still says "six" and omits the two new parity surfaces.
 
 **Recommendation:** Update GatewayTesting.md to "eight" and add bullets for the B8 new-COM-commands and buffered-data parity surfaces.
 
-**Resolution:** _(empty until closed)_
+**Resolution:** 2026-06-16: Updated `docs/GatewayTesting.md` — changed "five parity paths" to "seven", "All six tests" to "All eight tests", and added bullets for the B8 new-COM-commands surface (AuthenticateUser/ArchestrAUserToId/Suspend/Activate against an added-but-not-advised item) and the buffered-data surface (AddBufferedItem/SetBufferedUpdateInterval/Advise round-trip with at least one OnBufferedDataChange event, residual noted for multi-sample conversion).
 
 ### IntegrationTests-031
 
@@ -648,13 +648,13 @@ The prior `DashboardAuthenticator` ctor took `IOptions<GatewayOptions>`, so the
 | Severity | Low |
 | Category | Documentation & comments |
 | Location | `src/ZB.MOM.WW.MxGateway.IntegrationTests/WorkerLiveMxAccessSmokeTests.cs:672` |
-| Status | Open |
+| Status | Resolved |
 
 **Description:** The inline comment at line 672 says "Suspend / Activate against the advised item", but no `Advise` call is made between `AddItem` (line 616) and `CreateSuspendRequest` (line 677) — the item is added but not advised. The comment mislabels the COM subscription state under test (the parity assertion only requires a real reply, not a successful one).
 
 **Recommendation:** Change "against the advised item" to "against the added-but-not-advised item" (or remove "advised"), and note that Suspend/Activate is exercised without a prior Advise.
 
-**Resolution:** _(empty until closed)_
+**Resolution:** 2026-06-16: Rewrote the comment to "Suspend / Activate against the added-but-not-advised item (no Advise was issued between AddItem and this call)," making the COM subscription state explicit and noting that parity requires only a real reply, not a successful one.
 
 ### IntegrationTests-032
 
@@ -663,13 +663,13 @@ The prior `DashboardAuthenticator` ctor took `IOptions<GatewayOptions>`, so the
 | Severity | Low |
 | Category | Testing coverage |
 | Location | `src/ZB.MOM.WW.MxGateway.IntegrationTests/WorkerLiveMxAccessSmokeTests.cs:823-865` |
-| Status | Open |
+| Status | Resolved |
 
 **Description:** In the buffered-item test, when no sample-bearing `OnBufferedDataChange` batch arrives, the sample-predicate `TimeoutException` is caught and discarded (line 831) before asserting `bootstrapBufferedEvents > 0`. The final failure message ("No OnBufferedDataChange event arrived at all") conflates two failure modes (NoData bootstrap not delivered vs. delivered-but-no-sample), reducing residual diagnostic quality.
 
 **Recommendation:** Before nulling the batch, log the caught timeout message (e.g. `output.WriteLine($"B8: sample-bearing batch predicate timed out: {ex.Message}")`) so the residual log distinguishes the two cases.
 
-**Resolution:** _(empty until closed)_
+**Resolution:** 2026-06-16: Added `output.WriteLine($"B8: sample-bearing batch predicate timed out: {ex.Message}")` inside the `catch (TimeoutException ex)` block before nulling `bufferedBatch`, so the residual log clearly records the timeout detail and distinguishes "predicate timed out" from "no OnBufferedDataChange arrived at all".
 
 ### IntegrationTests-033
 
@@ -678,10 +678,10 @@ The prior `DashboardAuthenticator` ctor took `IOptions<GatewayOptions>`, so the
 | Severity | Low |
 | Category | Testing coverage |
 | Location | `src/ZB.MOM.WW.MxGateway.IntegrationTests/WorkerLiveMxAccessSmokeTests.cs:577-709` |
-| Status | Open |
+| Status | Deferred |
 
 **Description:** The new-COM-commands live test covers AuthenticateUser/ArchestrAUserToId/Suspend/Activate but not `AddItem2`/`Write2` — the B8 extended commands with a second context parameter introduced in the same bundle. Only live COM tests can verify the COM call succeeds with the correct argument split; a parity regression short-circuiting AddItem2/Write2 to InvalidRequest would not be caught.
 
 **Recommendation:** Add AddItem2/Write2 to the parity test (or a dedicated test) asserting each produces a real reply (not InvalidRequest) against a valid handle and item-definition split.
 
-**Resolution:** _(empty until closed)_
+**Resolution:** 2026-06-16: requires a live MXAccess rig + provider state not available on this dev box; add the AddItem2/Write2 parity assertions when running on the MXAccess host.