[backend/federation] Limit the maximum number of replies to backfill per post

Iceshrimp.Backend/Core/Federation/ActivityPub/ObjectResolver.cs

@@ -78,7 +78,7 @@ public class ObjectResolver(
 		}
 	}
 
-	public async IAsyncEnumerable<ASObject> IterateCollection(ASCollection? collection)
+	public async IAsyncEnumerable<ASObject> IterateCollection(ASCollection? collection, int pageLimit = 10)
 	{
 		if (collection == null) yield break;
 
@@ -91,10 +91,6 @@ public class ObjectResolver(
 			foreach (var item in collection.Items)
 				yield return item;
 
-		// we only limit based on pages here. the consumer of this iterator may
-		// additionally limit per-item via System.Linq.Async Take()
-		var pageLimit = 50;
-
 		// some remote software (e.g. fedibird) can get in a state where page.next == page.id
 		var visitedPages = new HashSet<string>();
 
@@ -118,6 +114,8 @@ public class ObjectResolver(
 				visitedPages.Add(page.Next.Id);
 			}
 
+			// we only limit based on pages here. the consumer of this iterator may
+			// additionally limit per-item via System.Linq.Async Take()
 			if (--pageLimit <= 0)
 				break;
 

Iceshrimp.Backend/Core/Services/NoteService.cs

@@ -1195,7 +1195,7 @@ public class NoteService(
 
 		_recursionLimit = recursionLimit;
 		await objectResolver.IterateCollection(repliesCollection)
-		                    .Take(100) // does this limit make sense?
+		                    .Take(50)
 		                    .Where(p => p.Id != null && (replyBackfillConfig.BackfillEverything || new Uri(p.Id).Authority == collectionId.Authority))
 		                    .Select(p => ResolveNoteAsync(p.Id!, null, fetchUser, forceRefresh: false))
 		                    .AwaitAllNoConcurrencyAsync();