Everything on, phase 4a: one answer everywhere for counts, search, collections and the instance API

Owner decision 2026-10-04: fix the mismatches and every other mismatch of the same kind.

- One counting rule (Domain/Privacy/Counted), Mastodon's. It is used for a persona's statuses_count, its outbox
  totalItems, NodeInfo localPosts and the instance status_count, which used to count four different things. It
  counts every post that is neither deleted nor a DM, boosts included, and circle and located posts too (owner
  decision). A group's count includes its remote members' posts.
- Users. Personas of banned or deleted roots no longer count, and are not found in search. NodeInfo now gives
  activeMonth and activeHalfyear, and the v2 instance gives active_month instead of a constant 0.
- replies_count counts only public and unlisted replies, so it no longer tells anyone that a private reply exists.
  Migration _012 recounts it.
- A remote account that deletes itself takes everything out of every count (GoneActors): its likes, downvotes,
  reactions and poll votes go and their counters come back, as do its boosts', replies' and quotes' counts, and its
  notifications. Lookups, account lists, search and favourited_by no longer show it. Migration _012 applies this to
  accounts already gone.
- Deleting a post also deletes its pins and the local boosts of it.
- /stalking gives the same total as following_count. Members are still never listed, and hide_collections is now
  always true, since the setting never did anything.
- Joining a community by invitation is following it, so /flock and /groupies agree; leaving unfollows.
- Search. Anyone may search, as on Mastodon; resolve and offset need a sign-in, offset pages, and deleted accounts
  are never found.
- notifications/unread_count counts what the list shows, and the owner's follower and following lists page with
  Link.
- The instance API advertises what is enforced:
  - max_characters, now enforced with a 422;
  - max_pinned_statuses = MaxPins;
  - the media types and limits MediaService and MediaOptions accept;
  - PollService's limits;
  - the configured languages;
  - no streaming URL until streaming exists.

  domain_count counts the servers we have exchanged with; which ones stays unpublished (peers is empty).
- Routes Mastodon answers now answer instead of 404:
  - directory, tags/{name}, timelines/link and identity_proofs;
  - instance/languages, translation_languages, domain_blocks and privacy_policy;
  - the v1 and v2 notification policy, and notification requests.

Also, from phase 3: a recovered password ends /clientapi sessions through a per-root SessionStamp claim instead of
comparing the JWT's whole-second nbf with the change time. That comparison let a token issued in the same second
survive, which made a test flaky.

671 tests pass.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01ELjqpznMFMNrJoJUj6K5p2

PrivaPub/Infrastructure/Data/Migrations/_012_counts_follow_one_rule.cs

@@ -0,0 +1,35 @@
+using MongoDB.Driver;
+using MongoDB.Entities;
+
+using PrivaPub.Federation.Inbox;
+using PrivaPub.Models.Post;
+using PrivaPub.Models.User;
+
+using PostEntity = PrivaPub.Models.Post.Post;
+
+namespace PrivaPub.Infrastructure.Data.Migrations
+{
+	// replies_count now counts only public and unlisted replies, and accounts that deleted themselves leave nothing in the
+	// counts (GoneActors). Both are recounted once for what was stored before.
+	public class _012_counts_follow_one_rule : IMigration
+	{
+		public async Task UpgradeAsync()
+		{
+			var counted = (await DB.Default.Find<PostEntity, string>()
+					.Match(p => p.AnsweringToPostId != null && !p.DeletedAt.HasValue && !p.AuthorGone
+						&& (p.Visibility == PostVisibility.Public || p.Visibility == PostVisibility.Unlisted))
+					.Project(p => p.AnsweringToPostId)
+					.ExecuteAsync())
+				.GroupBy(id => id)
+				.ToDictionary(g => g.Key, g => g.Count());
+			var stale = await DB.Default.Find<PostEntity>().Match(p => p.RepliesCount > 0).Project(p => p.Include(x => x.ID).Include(x => x.RepliesCount)).ExecuteAsync();
+			foreach (var post in stale.Where(p => counted.GetValueOrDefault(p.ID) != p.RepliesCount))
+				await DB.Default.Update<PostEntity>().MatchID(post.ID).Modify(p => p.RepliesCount, counted.GetValueOrDefault(post.ID)).ExecuteAsync();
+			foreach (var (id, count) in counted.Where(c => stale.All(p => p.ID != c.Key)))
+				await DB.Default.Update<PostEntity>().MatchID(id).Modify(p => p.RepliesCount, count).ExecuteAsync();
+
+			foreach (var gone in await DB.Default.Find<ForeignAvatar>().Match(a => a.DeletionAt != null && a.ForgottenAt == null).ExecuteAsync())
+				await GoneActors.Forget(gone, CancellationToken.None);
+		}
+	}
+}