Follow requests asked again, and followed accounts found by name

A server can take a Follow with 202 and drop it afterwards, as Pleroma does
while it cannot fetch our actor; the request then stayed pending for good.
Following again now sends an unanswered request once more, the same
activity, at most once an hour (a delivery's `again` key).

accounts/search takes following=true: only accounts the persona follows,
by the start of their name, display name or server, never resolved; a
client fills a list with it. "already take" becomes "already taken".

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

PrivaPub/Api/Mastodon/Controllers/AccountsController.cs

@@ -134,7 +134,9 @@ namespace PrivaPub.Api.Mastodon.Controllers
 
 		[HttpGet("/api/v1/accounts/search"), Scope("read:accounts")]
 		public async Task<IActionResult> Search([FromServices] AccountSearch search, CancellationToken token) =>
-			Json(await search.Find(Params.Get("q"), Params.Bool("resolve") == true && MyId != default, Limit(), token));
+			Json(Params.Bool("following") == true && MyId != default
+				? await search.Followed(MyId, Params.Get("q"), Limit(), token)
+				: await search.Find(Params.Get("q"), Params.Bool("resolve") == true && MyId != default, Limit(), token));
 
 		[HttpGet("/api/v1/accounts/{id}"), Scope("read:accounts", requiresUser: false), Microsoft.AspNetCore.Authorization.AllowAnonymous]
 		public async Task<IActionResult> Get(string id, CancellationToken token)

PrivaPub/Api/Mastodon/Mappers/AccountSearch.cs

@@ -21,6 +21,30 @@ namespace PrivaPub.Api.Mastodon.Mappers
 
 		public async Task<List<Account>> Find(string q, bool resolve, int limit, CancellationToken token) => await Find(q, resolve, limit, 0, token);
 
+		// following=true: only accounts the persona follows, matched by the start of their name, display name or server
+		// (what a client offers when adding to a list), read from what PrivaPub holds and never resolved
+		public async Task<List<Account>> Followed(string viewerId, string q, int limit, CancellationToken token)
+		{
+			q = q?.Trim().TrimStart('@') ?? string.Empty;
+			var ids = (await _dbEntities.Followings.Match(f => f.AvatarId == viewerId && f.State == Models.Social.FollowState.Accepted).ExecuteAsync(token))
+				.Select(f => f.TargetAccountId).Where(id => !string.IsNullOrEmpty(id)).ToList();
+			if (ids.Count == 0)
+				return new List<Account>();
+			var parts = q.Split('@');
+			var localDomain = new Uri(_localActors.BaseAddress).Authority;
+			bool Matches(string userName, string name, string domain) =>
+				userName?.StartsWith(parts[0], StringComparison.OrdinalIgnoreCase) == true
+					&& (parts.Length < 2 || domain?.StartsWith(parts[1], StringComparison.OrdinalIgnoreCase) == true)
+				|| parts.Length == 1 && name?.Contains(q, StringComparison.OrdinalIgnoreCase) == true;
+			var found = (await _dbEntities.Avatars.Match(a => ids.Contains(a.ID) && !a.DeletionAt.HasValue).ExecuteAsync(token))
+				.Where(a => Matches(a.UserName, a.Name, localDomain)).Select(a => (a.UserName, a.ID))
+				.Concat((await _dbEntities.ForeignAvatars.Match(f => ids.Contains(f.ID) && !f.DeletionAt.HasValue).ExecuteAsync(token))
+					.Where(f => Matches(f.UserName, f.Name, f.Domain)).Select(f => (f.UserName, f.ID)))
+				.OrderBy(a => a.UserName, StringComparer.OrdinalIgnoreCase).Take(limit).Select(a => a.ID).ToList();
+			var accounts = await _mapper.Accounts(found, token);
+			return found.Where(accounts.ContainsKey).Select(id => accounts[id]).ToList();
+		}
+
 		// gone accounts (remote ones that deleted themselves, personas of banned or deleted roots) are never found
 		public async Task<List<Account>> Find(string q, bool resolve, int limit, int offset, CancellationToken token)
 		{

PrivaPub/Controllers/ClientToServer/RootUserController.cs

@@ -227,7 +227,7 @@ namespace PrivaPub.Controllers.ClientToServer
 			if (string.Equals(avatarUserName, rootUserName?.Trim(), StringComparison.OrdinalIgnoreCase))
 				return Localizer["Your persona's username must differ from your login."];
 			if (await LocalActors.IsUserNameTaken(avatarUserName, token))
-				return Localizer["The username '{0}' is already take.", avatarUserName];
+				return Localizer["The username '{0}' is already taken.", avatarUserName];
 			return default;
 		}
 

PrivaPub/Domain/Social/FollowService.cs

@@ -105,6 +105,11 @@ namespace PrivaPub.Domain.Social
 				if (existing.ShowReblogs != showReblogs)
 					await DB.Default.Update<Following>().MatchID(existing.ID).Modify(f => f.ShowReblogs, showReblogs).ExecuteAsync(token);
 				existing.ShowReblogs = showReblogs;
+				// a request still unanswered is sent again, at most once an hour: a server can take a Follow (202) and
+				// drop it later, as one that cannot yet read our actor does; one that holds it already ignores the copy
+				if (existing.State == FollowState.Requested && remote != default)
+					await _delivery.Enqueue(follower, new[] { remote.InboxURL }, FollowActivity(follower, existing), token,
+						again: "again-" + DateTime.UtcNow.ToString("yyyyMMddHH", System.Globalization.CultureInfo.InvariantCulture));
 				return existing;
 			}
 

PrivaPub/Federation/Outbox/DeliveryService.cs

@@ -23,7 +23,9 @@ namespace PrivaPub.Federation.Outbox
 {
 	public interface IDeliveryService
 	{
-		Task Enqueue(LocalActor signer, IEnumerable<string> inboxes, JsonObject activity, CancellationToken token);
+		// again: a delivery made once more on purpose, which an earlier one of the same activity does not stop; deliveries
+		// with the same again are made once
+		Task Enqueue(LocalActor signer, IEnumerable<string> inboxes, JsonObject activity, CancellationToken token, string again = default);
 		Task EnqueueToFollowers(LocalActor signer, JsonObject activity, CancellationToken token, IEnumerable<string> extraInboxes = default);
 		Task<IReadOnlyList<string>> FollowerInboxes(LocalActor actor, CancellationToken token);
 	}
@@ -41,7 +43,7 @@ namespace PrivaPub.Federation.Outbox
 			_queue = queue;
 		}
 
-		public async Task Enqueue(LocalActor signer, IEnumerable<string> inboxes, JsonObject activity, CancellationToken token)
+		public async Task Enqueue(LocalActor signer, IEnumerable<string> inboxes, JsonObject activity, CancellationToken token, string again = default)
 		{
 			var body = activity.ToJsonString();
 			var activityId = activity["id"] is JsonValue id && id.TryGetValue<string>(out var text) ? text : default;
@@ -54,7 +56,7 @@ namespace PrivaPub.Federation.Outbox
 				{
 					Kind = JobKind.Deliver,
 					Host = target.uri.Host.ToLowerInvariant(),
-					DedupeKey = activityId == default ? default : $"{activityId}|{target.inbox}",
+					DedupeKey = activityId == default ? default : again == default ? $"{activityId}|{target.inbox}" : $"{activityId}|{target.inbox}|{again}",
 					Payload = JsonSerializer.Serialize(new DeliveryPayload(signer.Id, signer.Kind, target.inbox, body))
 				})
 				.ToList();

PrivaPub/Services/ClientToServer/Private/IPrivateAvatarUsersService.cs

@@ -52,7 +52,7 @@ namespace PrivaPub.Services.ClientToServer.Private
 					return result.Invalidate(_localizer["The username may contain only letters, digits and underscores."]);
 
 				if (await _localActors.IsUserNameTaken(userName, default))
-					return result.Invalidate(_localizer["The username '{0}' is already take.", userName]);
+					return result.Invalidate(_localizer["The username '{0}' is already taken.", userName]);
 
 				if (!await IsValidRootUser(form.RootId))
 					return result.Invalidate(_localizer["You can't do this action because of your account status."]);
@@ -71,7 +71,7 @@ namespace PrivaPub.Services.ClientToServer.Private
 				};
 				newAvatar.ID = (string)newAvatar.GenerateNewID();
 				if (!await _localActors.TryReserveUserName(userName, LocalActorKind.Person, newAvatar.ID, default))
-					return result.Invalidate(_localizer["The username '{0}' is already take.", userName]);
+					return result.Invalidate(_localizer["The username '{0}' is already taken.", userName]);
 				if (form.Settings is { IsDefault: false })
 					Apply(newAvatar.Settings, form.Settings);
 

PrivaPub/Services/GroupUsersService.cs

@@ -104,7 +104,7 @@ namespace PrivaPub.Services
 
 				var userName = form.UserName.ToLowerInvariant();
 				if (await _localActors.IsUserNameTaken(userName, token))
-					return result.Invalidate(_localizer["The username '{0}' is already take.", userName]);
+					return result.Invalidate(_localizer["The username '{0}' is already taken.", userName]);
 
 				var (privateKey, publicKey) = Keys.NewKeyPair();
 				var group = new GroupEntity
@@ -126,7 +126,7 @@ namespace PrivaPub.Services
 				};
 				group.ID = (string)group.GenerateNewID();
 				if (!await _localActors.TryReserveUserName(userName, LocalActorKind.Group, group.ID, token))
-					return result.Invalidate(_localizer["The username '{0}' is already take.", userName]);
+					return result.Invalidate(_localizer["The username '{0}' is already taken.", userName]);
 				var actor = _localActors.FromGroup(group);
 				group.Url = actor.Uri;
 				group.InboxURL = actor.Inbox;