P7: FEP-268d searchableBy decides what search finds

A remote account's searchableBy, and a post's own, outrank indexable in status search: Public lets anyone find a
public post, the author's followers only those who follow it, anything else nobody but those it already reaches
(their own, named, favourited, bookmarked or boosted posts). Read on actors and posts, kept through edits; PrivaPub
does not emit it.

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

PrivaPub/Api/Mastodon/Controllers/SearchController.cs

@@ -105,15 +105,30 @@ namespace PrivaPub.Api.Mastodon.Controllers
 			mine.UnionWith((await _dbEntities.Posts.Match(p => p.AuthorAccountId == MyId && ids.Contains(p.ReblogOfPostId) && !p.DeletedAt.HasValue).ExecuteAsync(token))
 				.Select(p => p.ReblogOfPostId));
 			var authors = candidates.Select(p => p.AuthorAccountId ?? p.GroupUserId).Where(a => a != default).Distinct().ToList();
-			var indexable = (await _dbEntities.Avatars.Match(a => authors.Contains(a.ID) && a.Settings.IsIndexable).ExecuteAsync(token)).Select(a => a.ID)
-				.Concat((await _dbEntities.ForeignAvatars.Match(f => authors.Contains(f.ID) && f.IsIndexable).ExecuteAsync(token)).Select(f => f.ID))
-				.ToHashSet();
+			var indexable = (await _dbEntities.Avatars.Match(a => authors.Contains(a.ID) && a.Settings.IsIndexable).ExecuteAsync(token)).Select(a => a.ID).ToHashSet();
+			// a remote author's searchableBy (FEP-268d) outranks its indexable, and a post's own outranks both
+			var remoteAuthors = (await _dbEntities.ForeignAvatars.Match(f => authors.Contains(f.ID)).ExecuteAsync(token)).ToDictionary(f => f.ID);
+			var stating = remoteAuthors.Values.Where(f => f.SearchableBy != default).Select(f => f.ActorURI)
+				.Concat(candidates.Where(p => p.SearchableBy != default).Select(p => p.ActorURI))
+				.Where(uri => uri != default).Distinct().ToList();
+			var followed = stating.Count == 0
+				? new HashSet<string>()
+				: (await _dbEntities.Followings.Match(f => f.AvatarId == MyId && stating.Contains(f.TargetActorURI) && f.State == Models.Social.FollowState.Accepted)
+					.ExecuteAsync(token)).Select(f => f.TargetActorURI).ToHashSet();
+			bool Searchable(PostEntity post, string author)
+			{
+				var remote = remoteAuthors.GetValueOrDefault(author);
+				var rule = post.SearchableBy ?? remote?.SearchableBy;
+				if (rule != default)
+					return Federation.Objects.ObjectShapes.Searchable(rule, remote?.FollowersURL, followed.Contains(post.ActorURI ?? string.Empty));
+				return remote?.IsIndexable == true || indexable.Contains(author);
+			}
 			var found = new List<PostEntity>();
 			foreach (var post in candidates)
 			{
 				var author = post.AuthorAccountId ?? post.GroupUserId;
 				var reachable = author == MyId && !post.IsFederatedCopy || mine.Contains(post.ID) || post.Mentions.Any(m => m.AccountId == MyId)
-					|| post.Visibility == PostVisibility.Public && indexable.Contains(author);
+					|| post.Visibility == PostVisibility.Public && Searchable(post, author);
 				if (reachable && await VisibilityPolicy.CanSee(post, MyId, token))
 					found.Add(post);
 				if (found.Count >= offset + limit)

PrivaPub/Federation/Actors/ActorDocument.cs

@@ -38,6 +38,7 @@ namespace PrivaPub.Federation.Actors
 		public string MovedTo { get; init; }
 		public string Moderators { get; init; }
 		public List<PostFlair> Flairs { get; init; } = new();
+		public List<string> SearchableBy { get; init; }
 		public List<string> AlsoKnownAs { get; init; } = new();//the accounts it says it also is (a Move's target names the moved one)
 		public DateTime? Published { get; init; }
 		public List<CustomEmoji> Emojis { get; init; } = new();
@@ -96,6 +97,7 @@ namespace PrivaPub.Federation.Actors
 				MovedTo = RemoteActorService.Text(root, "movedTo"),
 				Flairs = type != "Group" ? new() : ObjectShapes.Flairs(root.TryGetProperty("tag", out var labels) ? JsonNode.Parse(labels.GetRawText()) : default,
 					root.TryGetProperty("lemmy:tagsForPosts", out var older) ? JsonNode.Parse(older.GetRawText()) : default),
+				SearchableBy = root.TryGetProperty("searchableBy", out var searchable) ? ObjectShapes.SearchableBy(JsonNode.Parse(searchable.GetRawText())) : default,
 				Moderators = type == "Group" ? RemoteActorService.Text(root, "attributedTo") ?? RemoteActorService.Text(root, "moderators") : default,
 				AlsoKnownAs = root.TryGetProperty("alsoKnownAs", out var aliases) ? Uris(aliases) : new(),
 				Published = DateTimeOffset.TryParse(RemoteActorService.Text(root, "published"), CultureInfo.InvariantCulture, DateTimeStyles.AssumeUniversal, out var published)

PrivaPub/Federation/Actors/RemoteActorService.cs

@@ -236,6 +236,7 @@ namespace PrivaPub.Federation.Actors
 				.Modify(a => a.MovedToURL, Origin.Of(actor.MovedTo) == default ? default : actor.MovedTo)
 				.Modify(a => a.ModeratorsURL, Origin.Same(actor.Moderators, actor.Id) ? actor.Moderators : default)
 				.Modify(a => a.Flairs, actor.Flairs)
+				.Modify(a => a.SearchableBy, actor.SearchableBy)
 				.Modify(a => a.AlsoKnownAs, actor.AlsoKnownAs)
 				.Modify(a => a.Published, actor.Published)
 				.Modify(a => a.Emojis, actor.Emojis)

PrivaPub/Federation/Inbox/RemoteEdits.cs

@@ -39,6 +39,7 @@ namespace PrivaPub.Federation.Inbox
 			post.Event = note.Event ?? post.Event;
 			post.Place = note.Place;
 			post.Flairs = await RemotePosts.Flairs(note, post.AudienceURI, token);
+			post.SearchableBy = note.SearchableBy;
 			if (note.CommentsEnabled is { } enabled)
 				post.LockedAt = enabled ? null : post.LockedAt ?? DateTime.UtcNow;
 			if (!IsEdit(note, post))

PrivaPub/Federation/Inbox/RemotePosts.cs

@@ -106,6 +106,7 @@ namespace PrivaPub.Federation.Inbox
 				Excerpt = note.Excerpt,
 				Source = note.Source,
 				Poll = note.Poll,
+				SearchableBy = note.SearchableBy,
 				QuotePolicy = note.QuotePolicy,
 				ReplyPolicy = note.ReplyPolicy,
 				LikePolicy = note.LikePolicy,

PrivaPub/Federation/Objects/NoteParser.cs

@@ -41,6 +41,7 @@ namespace PrivaPub.Federation.Objects
 		public PostSource Source { get; init; }
 		public PostPoll Poll { get; init; }
 		public List<PostFlair> Flairs { get; init; } = new();
+		public List<string> SearchableBy { get; init; }
 		public InteractionRule QuotePolicy { get; init; }
 		public InteractionRule ReplyPolicy { get; init; }
 		public InteractionRule LikePolicy { get; init; }
@@ -121,6 +122,7 @@ namespace PrivaPub.Federation.Objects
 				Source = ObjectShapes.Source(note),
 				Poll = ObjectShapes.Poll(note),
 				Flairs = ObjectShapes.Flairs(note["tag"]),
+				SearchableBy = ObjectShapes.SearchableBy(note["searchableBy"]),
 				QuotePolicy = ObjectShapes.QuotePolicy(note),
 				ReplyPolicy = ObjectShapes.Policy(note, "canReply"),
 				LikePolicy = ObjectShapes.Policy(note, "canLike"),

PrivaPub/Federation/Objects/ObjectShapes.cs

@@ -100,6 +100,18 @@ namespace PrivaPub.Federation.Objects
 
 		const int MaxFlairs = 20;
 
+		// FEP-268d: who may find this in a search (Public, the author's followers, nobody else); null when not stated
+		public static List<string> SearchableBy(JsonNode node) => node switch
+		{
+			null => default,
+			JsonArray array => array.Select(Id).Where(id => id != default).Take(MaxAudience).ToList(),
+			_ when Id(node) is { } single => new List<string> { single },
+			_ => new List<string>()
+		};
+
+		public static bool Searchable(List<string> searchableBy, string followers, bool viewerFollows) =>
+			searchableBy.Any(Addressing.IsPublic) || viewerFollows && searchableBy.Any(w => w == followers || w.EndsWith("/followers", StringComparison.Ordinal));
+
 		// a post's flairs, or a community's (its `tag`, and PieFed's older `lemmy:tagsForPosts`), in both dialects
 		public static List<PostFlair> Flairs(params JsonNode[] lists) =>
 			lists.SelectMany(Objects)

PrivaPub/Models/Post/Post.cs

@@ -48,6 +48,8 @@ namespace PrivaPub.Models.Post
 		public PostPoll Poll { get; set; }
 		[BsonIgnoreIfNull]
 		public List<PostFlair> Flairs { get; set; }
+		[BsonIgnoreIfNull]
+		public List<string> SearchableBy { get; set; }//FEP-268d on the post itself: outranks its author's
 		public List<float> Location { get; set; } = new();
 		public float RangeKm { get; set; } = 5.0f;
 		[BsonIgnoreIfNull]

PrivaPub/Models/User/Avatar.cs

@@ -78,6 +78,7 @@ namespace PrivaPub.Models.User
 		public string OutboxURL { get; set; }
 		public string FeaturedURL { get; set; }//featured: the posts it pins
 		public List<PrivaPub.Models.Post.PostFlair> Flairs { get; set; } = new();//a community's labels for its posts
+		public List<string> SearchableBy { get; set; }//FEP-268d, when the account states it: outranks IsIndexable
 		public string ModeratorsURL { get; set; }//a community's attributedTo (Lemmy, PieFed, Mbin): the collection of its moderators
 		public List<AssertionKey> AssertionKeys { get; set; } = new();//its Ed25519 keys (FEP-521a), which prove what it sends (FEP-8b32)
 		public string WallURL { get; set; }//sm:wall (FEP-400e): where others write to it, Smithereen's walls