grpc: reuse GalaxyBrowseProjector.ResolveParentId from handler

src/ZB.MOM.WW.MxGateway.Server/Galaxy/GalaxyBrowseProjector.cs

@@ -62,7 +62,16 @@ public static class GalaxyBrowseProjector
         return new GalaxyBrowseChildrenResult(page, hasChildren, filtered.Children.Count, filterSignature);
     }
 
-    private static int ResolveParentId(GalaxyHierarchyCacheEntry entry, BrowseChildrenRequest request)
+    /// <summary>
+    ///     Resolves the request's parent oneof to a gobject id, throwing
+    ///     <see cref="RpcException"/> with <see cref="StatusCode.NotFound"/> when the
+    ///     parent does not exist. Public so the gRPC handler can compute the same
+    ///     parent id (needed for the page-token signature) without reimplementing the
+    ///     resolution rules.
+    /// </summary>
+    /// <param name="entry">The Galaxy hierarchy cache entry to query.</param>
+    /// <param name="request">The browse-children request.</param>
+    public static int ResolveParentId(GalaxyHierarchyCacheEntry entry, BrowseChildrenRequest request)
     {
         switch (request.ParentCase)
         {

src/ZB.MOM.WW.MxGateway.Server/Grpc/GalaxyRepositoryGrpcService.cs

@@ -128,8 +128,11 @@ public sealed class GalaxyRepositoryGrpcService(
         IReadOnlyList<string> browseSubtrees = ResolveBrowseSubtrees();
 
         // Resolve the parent id once so the page-token signature can include it
-        // and the projector sees the same resolved id when memoizing.
-        int parentId = ResolveParentIdForToken(entry, request);
+        // and the projector sees the same resolved id when memoizing. The projector
+        // re-resolves internally; with the by-name/by-path indexes on
+        // GalaxyHierarchyIndex that second call is O(1), so the redundancy is cheap
+        // and keeps the projector self-contained.
+        int parentId = GalaxyDb.GalaxyBrowseProjector.ResolveParentId(entry, request);
         string filterSignature = GalaxyDb.GalaxyBrowseProjector.ComputeFilterSignature(
             request, browseSubtrees, parentId);
         PageToken pageToken = ParsePageToken(request.PageToken, entry.Sequence, filterSignature);
@@ -283,32 +286,6 @@ public sealed class GalaxyRepositoryGrpcService(
         return Math.Min(pageSize, MaxDiscoverPageSize);
     }
 
-    // Lightweight parent resolver used only for signature computation. Re-throws
-    // NotFound consistently with the projector so the error surface matches.
-    private static int ResolveParentIdForToken(
-        GalaxyDb.GalaxyHierarchyCacheEntry entry,
-        BrowseChildrenRequest request)
-    {
-        return request.ParentCase switch
-        {
-            BrowseChildrenRequest.ParentOneofCase.None => 0,
-            BrowseChildrenRequest.ParentOneofCase.ParentGobjectId =>
-                request.ParentGobjectId == 0 ? 0
-                : entry.Index.ObjectViewsById.ContainsKey(request.ParentGobjectId)
-                    ? request.ParentGobjectId
-                    : throw new RpcException(new Status(StatusCode.NotFound, "BrowseChildren parent was not found.")),
-            BrowseChildrenRequest.ParentOneofCase.ParentTagName =>
-                entry.Index.ObjectViews.FirstOrDefault(
-                    v => string.Equals(v.Object.TagName, request.ParentTagName, StringComparison.OrdinalIgnoreCase))?.Object.GobjectId
-                ?? throw new RpcException(new Status(StatusCode.NotFound, "BrowseChildren parent was not found.")),
-            BrowseChildrenRequest.ParentOneofCase.ParentContainedPath =>
-                entry.Index.ObjectViews.FirstOrDefault(
-                    v => string.Equals(v.ContainedPath, request.ParentContainedPath, StringComparison.OrdinalIgnoreCase))?.Object.GobjectId
-                ?? throw new RpcException(new Status(StatusCode.NotFound, "BrowseChildren parent was not found.")),
-            _ => 0,
-        };
-    }
-
     private IReadOnlyList<string> ResolveBrowseSubtrees()
     {
         ApiKeyConstraints constraints = identityAccessor.Current?.EffectiveConstraints ?? ApiKeyConstraints.Empty;