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.

clients/python/src/zb_mom_ww_mxgateway/__init__.py

@@ -2,7 +2,7 @@
 
 from .auth import ApiKey, auth_metadata
 from .client import GatewayClient
-from .galaxy import GalaxyRepositoryClient
+from .galaxy import GalaxyRepositoryClient, LazyBrowseNode
 from .generated.galaxy_repository_pb2 import (
     DeployEvent,
     GalaxyAttribute,
@@ -19,19 +19,21 @@ from .errors import (
     MxGatewayTransportError,
     MxGatewayWorkerError,
 )
-from .options import ClientOptions
+from .options import BrowseChildrenOptions, ClientOptions
 from .session import Session
 from .values import MxValueView, from_mx_value, to_mx_value
 from .version import __version__
 
 __all__ = [
     "ApiKey",
+    "BrowseChildrenOptions",
     "ClientOptions",
     "DeployEvent",
     "GalaxyAttribute",
     "GalaxyObject",
     "GalaxyRepositoryClient",
     "GatewayClient",
+    "LazyBrowseNode",
     "MxAccessError",
     "MxGatewayAuthenticationError",
     "MxGatewayAuthorizationError",

clients/python/src/zb_mom_ww_mxgateway_cli/commands.py

@@ -769,7 +769,7 @@ def _build_write_bulk_entries(kwargs: dict[str, Any]):
     """
 
     handles = _parse_int_list(kwargs["item_handles"])
-    value_texts = _parse_string_list(kwargs["values"])
+    value_texts = _parse_string_list(kwargs["values"], param_hint="--values")
     if len(handles) != len(value_texts):
         raise click.UsageError(
             f"item-handles count ({len(handles)}) does not match values count ({len(value_texts)})",
@@ -1045,8 +1045,7 @@ async def _write2(**kwargs: Any) -> dict[str, Any]:
 async def _smoke(**kwargs: Any) -> dict[str, Any]:
     async with await _connect(kwargs) as client:
         session = await client.open_session(client_session_name=kwargs["client_name"])
-        closed = False
-        try:
+        async with session:
             server_handle = await session.register(kwargs["client_name"])
             item_handle = await session.add_item(server_handle, kwargs["item"])
             await session.advise(server_handle, item_handle)
@@ -1061,9 +1060,6 @@ async def _smoke(**kwargs: Any) -> dict[str, Any]:
                 "itemHandle": item_handle,
                 "events": [_message_dict(event) for event in events],
             }
-        finally:
-            if not closed:
-                await session.close()
 
 
 async def _galaxy_test_connection(**kwargs: Any) -> dict[str, Any]:
@@ -1487,10 +1483,10 @@ def _parse_datetime(raw_value: str) -> datetime:
     return parsed
 
 
-def _parse_string_list(raw_value: str) -> list[str]:
+def _parse_string_list(raw_value: str, param_hint: str = "--items") -> list[str]:
     values = [item.strip() for item in raw_value.split(",") if item.strip()]
     if not values:
-        raise click.BadParameter("at least one item is required", param_hint="--items")
+        raise click.BadParameter("at least one item is required", param_hint=param_hint)
     return values
 
 
@@ -1498,7 +1494,12 @@ def _parse_int_list(raw_value: str) -> list[int]:
     values = [item.strip() for item in raw_value.split(",") if item.strip()]
     if not values:
         raise click.BadParameter("at least one item handle is required", param_hint="--item-handles")
-    return [int(item) for item in values]
+    try:
+        return [int(item) for item in values]
+    except ValueError as exc:
+        raise click.BadParameter(
+            f"item handles must be integers: {exc}", param_hint="--item-handles"
+        ) from exc
 
 
 def _message_dict(message: Any) -> dict[str, Any]: