refactor(galaxy): migrate to ZB.MOM.WW.MxGateway.* nupkg packages

Imports the freshly-rebuilt ZB.MOM.WW.MxGateway.Client + ZB.MOM.WW.MxGateway.Contracts
nupkgs (0.1.0) from /tmp/mxgw-dist. Replaces the vendored libs/ DLLs and the
pre-restructure MxGateway.* namespaces across the runtime Galaxy driver,
Galaxy.Browser, and their tests.

Key changes:
- nuget-packages/ added as a local feed via NuGet.config; .gitignore exempts it
  from the *.nupkg rule so the packages are tracked
- Directory.Packages.props pins both packages at 0.1.0
- 4 csprojs swap <Reference HintPath="libs/...dll"/> for <PackageReference/>
- 36 .cs files renamed `using MxGateway.*` -> `using ZB.MOM.WW.MxGateway.*`
- libs/ removed (vendored DLLs + README.md)

GalaxyBrowseSession rewritten around the new lazy API:
- RootAsync calls GalaxyRepositoryClient.BrowseAsync (returns LazyBrowseNodes)
  and caches them by TagName instead of bulk-fetching the whole hierarchy
- ExpandAsync looks up the cached LazyBrowseNode and calls its ExpandAsync,
  giving true one-wire-call-per-click instead of in-memory parent/child scan
- _byGobjectId + _hasChildrenSet dropped (LazyBrowseNode carries HasChildrenHint)
- AttributesAsync unchanged (already uses DiscoverHierarchyAsync MaxDepth=0)

Tests: Galaxy.Tests 245/245, Galaxy.Browser.Tests 10/10, AdminUI.Tests 66/66.
Pre-existing 12 solution errors unchanged (test sinks + Cli XML comments).

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Browser/GalaxyBrowseSession.cs

@@ -1,29 +1,26 @@
 using System.Collections.Concurrent;
-using MxGateway.Client;
-using MxGateway.Contracts.Proto.Galaxy;
+using ZB.MOM.WW.MxGateway.Client;
+using ZB.MOM.WW.MxGateway.Contracts.Proto.Galaxy;
 using ZB.MOM.WW.OtOpcUa.Commons.Browsing;
 
 namespace ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Browser;
 
 /// <summary>
-///     Galaxy browse over the gateway's <see cref="GalaxyRepositoryClient"/>.
-///     The gateway returns the deployed hierarchy as a flat <see cref="GalaxyObject"/>
-///     list, so this session fetches the full set once on <see cref="RootAsync"/>,
-///     caches it by <c>TagName</c> (and <c>GobjectId</c> for parent lookup), and serves
-///     subsequent <see cref="ExpandAsync"/> calls in-memory. Attribute fetches are
-///     per-object via <c>DiscoverHierarchyAsync(MaxDepth=0, IncludeAttributes=true)</c>.
-///     Owns the supplied <see cref="GalaxyRepositoryClient"/> and disposes it
-///     best-effort. (Browse does not need an <c>MxGatewaySession</c> — that's only
-///     required for live subscribe/write paths handled by the runtime driver.)
+///     Lazy Galaxy browse over <see cref="GalaxyRepositoryClient.BrowseAsync"/>.
+///     <see cref="RootAsync"/> returns the top-level <see cref="LazyBrowseNode"/>s
+///     directly from the gateway; <see cref="ExpandAsync"/> fetches the direct children
+///     of a previously-handed-out node via <see cref="LazyBrowseNode.ExpandAsync"/>
+///     (one wire call per click, paginated internally by the client). Attribute fetches
+///     are per-object via <c>DiscoverHierarchyAsync(MaxDepth=0, IncludeAttributes=true)</c>.
+///     Owns the supplied <see cref="GalaxyRepositoryClient"/> and disposes it best-effort.
 /// </summary>
 internal sealed class GalaxyBrowseSession : IBrowseSession
 {
     private readonly GalaxyRepositoryClient _client;
-    private readonly ConcurrentDictionary<string, GalaxyObject> _byTagName = new(StringComparer.Ordinal);
-    private readonly ConcurrentDictionary<int, GalaxyObject> _byGobjectId = new();
-    private volatile bool _disposed;
+    private readonly ConcurrentDictionary<string, LazyBrowseNode> _byTagName = new(StringComparer.Ordinal);
     private readonly SemaphoreSlim _rootGate = new(1, 1);
-    private HashSet<int> _hasChildrenSet = new();
+    private volatile bool _disposed;
+    private IReadOnlyList<LazyBrowseNode>? _roots;
 
     /// <summary>Opaque token identifying this session in the AdminUI registry.</summary>
     public Guid Token { get; } = Guid.NewGuid();
@@ -33,19 +30,20 @@ internal sealed class GalaxyBrowseSession : IBrowseSession
 
     /// <summary>
     ///     Initializes a new session wrapping a connected repository client. The factory
-    ///     in <c>GalaxyDriverBrowser</c> (Task 9) constructs the client via
+    ///     in <c>GalaxyDriverBrowser</c> constructs the client via
     ///     <see cref="GalaxyRepositoryClient.Create"/> and hands it off here for the
     ///     session's lifetime.
     /// </summary>
-    /// <param name="client">Galaxy repository client to query for hierarchy and attributes.</param>
+    /// <param name="client">Galaxy repository client to query for browse and attributes.</param>
     internal GalaxyBrowseSession(GalaxyRepositoryClient client)
     {
         _client = client ?? throw new ArgumentNullException(nameof(client));
     }
 
     /// <summary>
-    ///     Fetches the full Galaxy hierarchy from the gateway, populates the cache,
-    ///     and returns the top-level objects (those with no parent in the deployed model).
+    ///     Fetches the top-level <see cref="LazyBrowseNode"/>s from the gateway and
+    ///     returns them as <see cref="BrowseNode"/>s. Result is cached; a second call
+    ///     returns the cached roots without a re-fetch.
     /// </summary>
     public async Task<IReadOnlyList<BrowseNode>> RootAsync(CancellationToken cancellationToken)
     {
@@ -53,29 +51,11 @@ internal sealed class GalaxyBrowseSession : IBrowseSession
         await _rootGate.WaitAsync(cancellationToken).ConfigureAwait(false);
         try
         {
-            var all = await _client.DiscoverHierarchyAsync(
-                new DiscoverHierarchyOptions { IncludeAttributes = false }, cancellationToken)
+            _roots ??= await _client.BrowseAsync(new BrowseChildrenOptions(), cancellationToken)
                 .ConfigureAwait(false);
 
-            // Populate caches so later ExpandAsync calls can resolve children in-memory.
-            foreach (var obj in all)
-            {
-                _byTagName[obj.TagName] = obj;
-                _byGobjectId[obj.GobjectId] = obj;
-            }
-
-            // Precompute the set of GobjectIds that appear as a parent — used by
-            // Project to compute HasChildrenHint in O(1) instead of O(n²).
-            _hasChildrenSet = new HashSet<int>(_byGobjectId.Values.Select(o => o.ParentGobjectId));
-
-            // Roots are objects whose parent isn't part of the returned set (typically
-            // ParentGobjectId == 0 for WinPlatforms / top-level Areas).
-            var roots = all
-                .Where(o => o.ParentGobjectId == 0 || !_byGobjectId.ContainsKey(o.ParentGobjectId))
-                .ToList();
-
             LastUsedUtc = DateTime.UtcNow;
-            return Project(roots);
+            return Project(_roots);
         }
         finally
         {
@@ -84,27 +64,24 @@ internal sealed class GalaxyBrowseSession : IBrowseSession
     }
 
     /// <summary>
-    ///     Returns the direct children of the cached Galaxy object identified by
-    ///     <paramref name="nodeId"/> (the object's <c>TagName</c>). Throws
-    ///     <see cref="ArgumentException"/> if the tag hasn't been handed out by a
-    ///     prior Root/Expand call (i.e. it's not in the cache).
+    ///     Fetches the direct children of the cached node identified by
+    ///     <paramref name="nodeId"/> (the object's <c>TagName</c>) via
+    ///     <see cref="LazyBrowseNode.ExpandAsync"/>. Throws <see cref="ArgumentException"/>
+    ///     if the tag hasn't been handed out by a prior Root/Expand call.
     /// </summary>
-    public Task<IReadOnlyList<BrowseNode>> ExpandAsync(string nodeId, CancellationToken cancellationToken)
+    public async Task<IReadOnlyList<BrowseNode>> ExpandAsync(string nodeId, CancellationToken cancellationToken)
     {
         ObjectDisposedException.ThrowIf(_disposed, this);
-        if (!_byTagName.TryGetValue(nodeId, out var parent))
+        if (!_byTagName.TryGetValue(nodeId, out var node))
         {
             throw new ArgumentException(
                 $"Galaxy object '{nodeId}' is not in the current browse-session cache. " +
                 "Re-open the browser or expand its parent first.", nameof(nodeId));
         }
 
-        var children = _byGobjectId.Values
-            .Where(o => o.ParentGobjectId == parent.GobjectId)
-            .ToList();
-
+        await node.ExpandAsync(cancellationToken).ConfigureAwait(false);
         LastUsedUtc = DateTime.UtcNow;
-        return Task.FromResult(Project(children));
+        return Project(node.Children);
     }
 
     /// <summary>
@@ -143,29 +120,25 @@ internal sealed class GalaxyBrowseSession : IBrowseSession
     }
 
     /// <summary>
-    ///     Projects <see cref="GalaxyObject"/>s to <see cref="BrowseNode"/>s, ensuring
-    ///     every projected object is also written to the by-tag cache so later
-    ///     <see cref="ExpandAsync"/> calls can find it. Galaxy nodes are always
-    ///     <see cref="BrowseNodeKind.Folder"/> — leaves only appear in the attribute
-    ///     side-panel, never in the tree.
+    ///     Projects <see cref="LazyBrowseNode"/>s to <see cref="BrowseNode"/>s, caching
+    ///     each by <c>TagName</c> so a subsequent <see cref="ExpandAsync"/> can locate
+    ///     it. Galaxy nodes are always <see cref="BrowseNodeKind.Folder"/> — leaves only
+    ///     appear in the attribute side-panel.
     /// </summary>
-    private IReadOnlyList<BrowseNode> Project(IReadOnlyList<GalaxyObject> nodes)
+    private IReadOnlyList<BrowseNode> Project(IReadOnlyList<LazyBrowseNode> nodes)
     {
         var result = new List<BrowseNode>(nodes.Count);
-        foreach (var obj in nodes)
+        foreach (var n in nodes)
         {
-            // Belt-and-braces: ensure the cache holds every node we hand back so
-            // ExpandAsync can resolve it on the next round-trip.
-            _byTagName[obj.TagName] = obj;
-            _byGobjectId[obj.GobjectId] = obj;
-
-            var displayName = !string.IsNullOrEmpty(obj.ContainedName) ? obj.ContainedName : obj.TagName;
-            var hasChildrenHint = _hasChildrenSet.Contains(obj.GobjectId);
+            _byTagName[n.Object.TagName] = n;
+            var displayName = !string.IsNullOrEmpty(n.Object.ContainedName)
+                ? n.Object.ContainedName
+                : n.Object.TagName;
             result.Add(new BrowseNode(
-                NodeId: obj.TagName,
+                NodeId: n.Object.TagName,
                 DisplayName: displayName,
                 Kind: BrowseNodeKind.Folder,
-                HasChildrenHint: hasChildrenHint));
+                HasChildrenHint: n.HasChildrenHint));
         }
         return result;
     }

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Browser/GalaxyDriverBrowser.cs

@@ -2,7 +2,7 @@ using System.Text.Json;
 using System.Text.Json.Serialization;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
-using MxGateway.Client;
+using ZB.MOM.WW.MxGateway.Client;
 using ZB.MOM.WW.OtOpcUa.Commons.Browsing;
 using ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Config;
 

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Browser/ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Browser.csproj

@@ -13,23 +13,8 @@
         <InternalsVisibleTo Include="ZB.MOM.WW.OtOpcUa.Driver.Galaxy.Browser.Tests" />
     </ItemGroup>
     <ItemGroup>
-        <!-- Vendored mxaccessgw .NET client — same DLLs as Driver.Galaxy.
-             See Driver.Galaxy/libs/README.md for the unwinding plan. -->
-        <Reference Include="MxGateway.Client">
-            <HintPath>..\ZB.MOM.WW.OtOpcUa.Driver.Galaxy\libs\MxGateway.Client.dll</HintPath>
-            <Private>true</Private>
-        </Reference>
-        <Reference Include="MxGateway.Contracts">
-            <HintPath>..\ZB.MOM.WW.OtOpcUa.Driver.Galaxy\libs\MxGateway.Contracts.dll</HintPath>
-            <Private>true</Private>
-        </Reference>
-    </ItemGroup>
-    <ItemGroup>
-        <!-- Transitive deps of the vendored MxGateway.Client.dll -->
-        <PackageReference Include="Google.Protobuf" />
-        <PackageReference Include="Grpc.Core.Api" />
-        <PackageReference Include="Grpc.Net.Client" />
+        <PackageReference Include="ZB.MOM.WW.MxGateway.Client" />
+        <PackageReference Include="ZB.MOM.WW.MxGateway.Contracts" />
         <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" />
-        <PackageReference Include="Polly.Core" />
     </ItemGroup>
 </Project>