Posts reach their audience, edits follow them, deletes leave a tombstone

OutboxPublisher works out who a post goes to, Mastodon's way: followers'
shared inboxes for public, unlisted and followers-only; every mentioned
remote account's own inbox; the recipients only for direct; the parent's
author for a reply; a community's followers for a post in it; nobody for
a circle. Creates, updates and deletes all use it.

- Local posts take a visibility (public, unlisted, followers-only) and a
  spoiler text next to the content-warning flag.
- /clientapi/post/update keeps the previous version as a revision,
  re-renders, and sends Update{Note} with `updated` to the same to/cc.
- Deleting is now soft: the content, title, spoiler, media and revisions
  are cleared, timeline entries removed, the parent's reply count goes
  down, Delete goes to the stored audience, and the object answers 410
  with a Tombstone instead of 404.
- Editing a persona's profile sends Update{Person} to its followers.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012CzABvBkbcFqoHdmi8b9WB

PrivaPub/Federation/Outbox/OutboxPublisher.cs

@@ -0,0 +1,95 @@
+using PrivaPub.Federation.Actors;
+using PrivaPub.Federation.Rendering;
+using PrivaPub.Models.Federation;
+using PrivaPub.Models.Post;
+using PrivaPub.StaticServices;
+
+using System.Text.Json.Nodes;
+
+using PostEntity = PrivaPub.Models.Post.Post;
+
+namespace PrivaPub.Federation.Outbox
+{
+	public interface IOutboxPublisher
+	{
+		Task<IReadOnlyList<string>> Audience(LocalActor author, PostEntity post, CancellationToken token);
+		Task Publish(LocalActor author, PostEntity post, JsonObject activity, CancellationToken token);
+		Task PublishProfile(LocalActor actor, CancellationToken token);
+	}
+
+	public class OutboxPublisher : IOutboxPublisher
+	{
+		readonly DbEntities _dbEntities;
+		readonly ILocalActorService _localActors;
+		readonly IDeliveryService _delivery;
+
+		public OutboxPublisher(DbEntities dbEntities, ILocalActorService localActors, IDeliveryService delivery)
+		{
+			_dbEntities = dbEntities;
+			_localActors = localActors;
+			_delivery = delivery;
+		}
+
+		public async Task<IReadOnlyList<string>> Audience(LocalActor author, PostEntity post, CancellationToken token)
+		{
+			if (post.Visibility is PostVisibility.Circle or PostVisibility.LocalGeo || post.IsLocalOnly)
+				return Array.Empty<string>();
+
+			var inboxes = new List<string>();
+			if (post.Visibility is PostVisibility.Public or PostVisibility.Unlisted or PostVisibility.FollowersOnly)
+				inboxes.AddRange(await _delivery.FollowerInboxes(author, token));
+
+			var addressed = post.Mentions.Where(m => !m.IsLocal).Select(m => m.ActorURI)
+				.Concat(post.Visibility == PostVisibility.Direct ? post.To.Concat(post.Cc) : Enumerable.Empty<string>())
+				.Where(uri => !uri.StartsWith(author.BaseAddress + "/", StringComparison.OrdinalIgnoreCase))
+				.Distinct(StringComparer.Ordinal)
+				.ToList();
+			foreach (var uri in addressed)
+			{
+				var actor = await _dbEntities.ForeignAvatars.Match(a => a.ActorURI == uri).ExecuteFirstAsync(token);
+				if (actor != default && !string.IsNullOrEmpty(actor.InboxURL))
+					inboxes.Add(actor.InboxURL);
+			}
+
+			if (post.Visibility != PostVisibility.Direct && !string.IsNullOrEmpty(post.InReplyToAccountId))
+			{
+				var parentAuthor = await _dbEntities.ForeignAvatars.MatchID(post.InReplyToAccountId).ExecuteFirstAsync(token);
+				if (parentAuthor != default && !string.IsNullOrEmpty(parentAuthor.InboxURL))
+					inboxes.Add(parentAuthor.InboxURL);
+			}
+
+			if (!string.IsNullOrEmpty(post.GroupId) && post.Visibility is PostVisibility.Public or PostVisibility.Unlisted)
+			{
+				var group = await _localActors.FindById(LocalActorKind.Group, post.GroupId, token);
+				if (group is { IsFederated: true })
+					inboxes.AddRange(await _delivery.FollowerInboxes(group, token));
+			}
+
+			return inboxes.Where(i => !string.IsNullOrEmpty(i)).Distinct(StringComparer.Ordinal).ToList();
+		}
+
+		public async Task Publish(LocalActor author, PostEntity post, JsonObject activity, CancellationToken token)
+		{
+			var inboxes = await Audience(author, post, token);
+			if (inboxes.Count > 0)
+				await _delivery.Enqueue(author, inboxes, activity, token);
+		}
+
+		public async Task PublishProfile(LocalActor actor, CancellationToken token)
+		{
+			var document = ActivityPubRenderer.Actor(actor);
+			document.Remove("@context");
+			var update = new JsonObject
+			{
+				["@context"] = ActivityPubRenderer.Context(),
+				["id"] = actor.ActivityUri($"update-profile-{DateTimeOffset.UtcNow.ToUnixTimeMilliseconds()}"),
+				["type"] = "Update",
+				["actor"] = actor.Uri,
+				["to"] = new JsonArray(ActivityPubRenderer.Public),
+				["cc"] = new JsonArray(actor.Followers),
+				["object"] = document
+			};
+			await _delivery.EnqueueToFollowers(actor, update, token);
+		}
+	}
+}