Personas have walls their followers write on

Owner decision of 2026-10-06 (G-0009, FEP-400e). A persona's actor names its wall (…/graffiti, sm:wall) and, in
Smithereen's privacySettings, that its followers may write on it. A public post that is not a reply, sent with the wall
as its target by an account following the persona, is hosted: the persona is notified, it reaches the persona's and its
followers' homes, and the followers' servers and the author's are told with Add{Note}. The persona deletes it with
DELETE /api/v1/statuses/:id, which sends Remove{Note}; Smithereen deletes the post then. The wall lists the persona's
public posts that start a thread and what was written on it.

Elsewhere: an account's Add{Note} on its own wall shows the post to its followers here as on that wall (privapub.wall on
the status), and its Remove takes it away. An Add or Remove naming a collection of the account's own server PrivaPub
does not know has its document read again first, at most hourly: accounts kept before walls were read had none.

Checked live: Smithereen 40 checks (G-0009 closed); GoToSocial and Mastodon unchanged (121).

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

PrivaPub/Api/Mastodon/Controllers/StatusesController.cs

@@ -34,10 +34,13 @@ namespace PrivaPub.Api.Mastodon.Controllers
 		readonly Domain.Media.IMediaService _media;
 
 		readonly IParticipations _participations;
+		readonly Federation.Actors.IWalls _walls;
 
 		public StatusesController(IStatusService statuses, MastodonMapper mapper, DbEntities dbEntities, IMemoryCache cache, IQuoteService quotes,
-			IOutboxPublisher outbox, PrivaPub.Infrastructure.Jobs.IJobQueue jobs, Domain.Media.IMediaService media, IParticipations participations = default)
+			IOutboxPublisher outbox, PrivaPub.Infrastructure.Jobs.IJobQueue jobs, Domain.Media.IMediaService media, IParticipations participations = default,
+			Federation.Actors.IWalls walls = default)
 		{
+			_walls = walls;
 			_participations = participations;
 			_jobs = jobs;
 			_media = media;
@@ -161,7 +164,7 @@ namespace PrivaPub.Api.Mastodon.Controllers
 		{
 			var before = await _dbEntities.Posts.Match(p => p.ID == id && p.GroupUserId == MyId && !p.IsFederatedCopy && !p.DeletedAt.HasValue).ExecuteFirstAsync(token);
 			if (before == default)
-				return NotFoundError();
+				return await OffWall(id, token);
 			var status = await _mapper.Status(before, MyId, token);
 			var outcome = await _statuses.Remove(Me, id, token);
 			if (!outcome.Ok)
@@ -174,6 +177,20 @@ namespace PrivaPub.Api.Mastodon.Controllers
 			return Json(status);
 		}
 
+		// someone's post on the persona's wall (FEP-400e), taken off it: as on Smithereen, the owner of a wall deletes what is on it
+		async Task<IActionResult> OffWall(string id, CancellationToken token)
+		{
+			var walled = _walls == default
+				? default
+				: await _dbEntities.Posts.Match(p => p.ID == id && p.WallOwnerAccountId == MyId && p.IsFederatedCopy && !p.DeletedAt.HasValue).ExecuteFirstAsync(token);
+			if (walled == default)
+				return NotFoundError();
+			var status = await _mapper.Status(walled, MyId, token);
+			if (!await _walls.Remove(Me, walled, token))
+				return NotFoundError();
+			return Json(status);
+		}
+
 		[HttpGet("/api/v1/statuses/{id}/context"), Scope("read:statuses", requiresUser: false), Microsoft.AspNetCore.Authorization.AllowAnonymous]
 		public async Task<IActionResult> Context(string id, CancellationToken token)
 		{

PrivaPub/Api/Mastodon/Entities/Entities.cs

@@ -77,6 +77,7 @@
 		public PrivaPubAudio Audio { get; set; }
 		public PrivaPubEvent Event { get; set; }
 		public PrivaPubPlace Place { get; set; }//a remote post's own place (Pixelfed), shown only
+		public Account Wall { get; set; }//whose wall it was written on (FEP-400e), when not its author's
 		public PrivaPubVotes Votes { get; set; } = new();
 	}
 

PrivaPub/Api/Mastodon/Mappers/MastodonMapper.cs

@@ -203,7 +203,7 @@ namespace PrivaPub.Api.Mastodon.Mappers
 			var mentionAccounts = mentionUris.Count == 0
 				? new Dictionary<string, ForeignAvatar>()
 				: (await _dbEntities.ForeignAvatars.Match(f => mentionUris.Contains(f.ActorURI)).ExecuteAsync(token)).ToDictionary(f => f.ActorURI);
-			var accounts = await Accounts(all.Select(AuthorOf), token);
+			var accounts = await Accounts(all.Select(AuthorOf).Concat(all.Select(p => p.WallOwnerAccountId).Where(w => w != default)), token);
 
 			var ids = all.Select(p => p.ID).ToList();
 			var favourited = viewerId == default
@@ -277,7 +277,7 @@ namespace PrivaPub.Api.Mastodon.Mappers
 					Card = Card(post),
 					Poll = Poll(post, viewerId, ownVotes.GetValueOrDefault(post.ID)),
 					Emojis = Emojis(post.Emojis),
-					Privapub = Extension(post),
+					Privapub = Extension(post, accounts),
 					EmojiReactions = reactions.GetValueOrDefault(post.ID) ?? new(),
 					Pleroma = new PleromaStatus { EmojiReactions = reactions.GetValueOrDefault(post.ID) ?? new() },
 					Mentions = post.Mentions.Where(m => !m.Silent).Select(m => Mention(m, mentionAccounts)).Where(m => m != default).ToList(),
@@ -480,8 +480,9 @@ namespace PrivaPub.Api.Mastodon.Mappers
 		List<CustomEmojiEntity> Emojis(IEnumerable<CustomEmoji> emojis) =>
 			emojis?.Select(e => new CustomEmojiEntity { Shortcode = e.Shortcode, Url = Proxied(e.URL), StaticUrl = Proxied(e.URL) }).ToList() ?? new();
 
-		PrivaPubStatus Extension(PostEntity post) => new()
+		PrivaPubStatus Extension(PostEntity post, Dictionary<string, Account> accounts) => new()
 		{
+			Wall = post.WallOwnerAccountId == default || post.WallOwnerAccountId == AuthorOf(post) ? default : accounts.GetValueOrDefault(post.WallOwnerAccountId),
 			ObjectType = post.ObjectType,
 			Locked = post.LockedAt.HasValue,
 			Approval = post.Approval is ApprovalState.Pending or ApprovalState.Rejected ? post.Approval.ToString().ToLowerInvariant() : default,