A community announces back to its author's own server

Lemmy keeps its user's post in a community pending until the community announces it back. A community hosted here
announced only to its followers, so a post from a server where nobody follows the community stayed pending there; the
author's own server (its shared inbox) now gets the announces too. INTEROP records, confirmed live, why Lemmy refuses
our Flags (an Application reporter, no `to`, an array object). FEDERATION.md's custom emoji line is put back before the
replies paragraph.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01LsXgEaXee4GCU1hwYgPJXw

PrivaPub.Tests/Federation/GroupTests.cs

@@ -125,6 +125,21 @@ namespace PrivaPub.Tests.Federation
 			Assert.True(await DB.Default.Find<Post>().Match(p => p.GroupId == community.Id && p.ActorURI == stranger.Id).ExecuteAnyAsync(token));
 		}
 
+		// Lemmy keeps its user's post pending until the community announces it back, whether anyone there follows the
+		// community or not
+		[Fact]
+		public async Task A_post_into_a_community_is_announced_back_to_its_authors_server_though_nobody_there_follows_it()
+		{
+			var (_, owner) = await _harness.Persona("owner");
+			var (_, community) = await Group(GroupKind.Community, PostingPolicy.Anyone, owner.Id);
+			var stranger = new RemoteActor(_harness.Peer, "stranger", sharedInbox: true);
+
+			await _harness.Deliver(stranger, "/human-centipede", Create(stranger, new[] { community.Uri, Addressing.Public }, community.Uri));
+
+			var announces = (await _harness.Outgoing(stranger.SharedInbox)).Where(a => a["actor"]!.GetValue<string>() == community.Uri).ToList();
+			Assert.Contains(announces, a => a["object"] is JsonObject inner && inner["type"]!.GetValue<string>() == "Create");
+		}
+
 		[Fact]
 		public async Task Mentioning_a_community_posts_into_it_as_a_titled_page()
 		{