Personas a remote post is addressed to see it, named or not

A remote post decided who here may see it by its Mention tags alone. A
followers-only post addressed in to or cc to a persona without naming
it (Akkoma's to[], or a GoToSocial edit that took the @name out while
the post stayed addressed to the persona) was hidden from that persona.
Such personas are now kept as silent mentions, as Mastodon does: they
see the post and it reaches their home, and no list shows them as
mentioned. An edit never narrows who a post was for.

The GoToSocial note that showed it is the first captured fixture
(Fixtures/gotosocial), and parses with its lone tag, to and cc.

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

PrivaPub.Tests/Federation/NoteParserTests.cs

@@ -57,6 +57,19 @@ namespace PrivaPub.Tests.Federation
 			Assert.Null(note.Updated);
 		}
 
+		// GoToSocial writes a lone tag, and lone to and cc, as plain values instead of arrays (captured by the town)
+		[Fact]
+		public void Reads_a_gotosocial_reply_whose_only_tag_and_audience_are_single_values()
+		{
+			var note = NoteParser.Parse(JsonNode.Parse(File.ReadAllText(Path.Combine(AppContext.BaseDirectory, "Fixtures", "gotosocial",
+				"followers-only-reply-one-tag.json"))));
+
+			var mention = Assert.Single(note.Mentions);
+			Assert.Equal("https://privapub.test/peasants/flor_pp98", mention.ActorURI);
+			Assert.Equal(["https://gts.test/users/ines_gt59/followers"], note.To);
+			Assert.Equal(["https://privapub.test/peasants/flor_pp98"], note.Cc);
+		}
+
 		[Fact]
 		public void Reads_a_lemmy_page_with_a_title()
 		{