Outbound documents speak Mastodon's dialect under PrivaPub's route names

Local text (Domain/Content/ContentRenderer): Markdig with raw HTML off and
autolinks, or plain text for API clients; then @user and @user@host are
resolved (locally or through WebFinger) into Mastodon's h-card markup and
#tags into hashtag links, skipping code, links and e-mail addresses. A
post stores the result, its mentions and its tags, and is delivered to
the mentioned actors and the parent's author as well as to followers.

Renderer:
- Mastodon's @context (toot, schema PropertyValue, discoverable,
  indexable, blurhash, focalPoint, featured, alsoKnownAs, movedTo) and
  FEP-2c59's webfinger;
- an actor's url is its HTML page, its fields are PropertyValue
  attachments, published is cut to the day and indexable is false;
- a note's content is the stored rendering; a title becomes name and a
  bold first line, a content warning without its own text is summarised
  by the title or "Content warning"; Mention and Hashtag tags, contentMap,
  updated, and to/cc by visibility.

Routes take the agreed names: /groupies, /stalking, /scribbles/{id},
/grunts/{id} (a Create resolves), /whispers/{id} for a DM's context. The
outbox is a collection with a first page, paged by max_id. A browser
asking for an actor or a note is redirected to /@user, and WebFinger's
profile-page points there.

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

PrivaPub/Services/PostsService.cs

@@ -13,6 +13,7 @@ using PrivaPub.StaticServices;
 using System.Text.Json.Nodes;
 
 using PostEntity = PrivaPub.Models.Post.Post;
+using PrivaPub.Domain.Content;
 using PrivaPub.Federation.Actors;
 using PrivaPub.Federation.Rendering;
 using PrivaPub.Federation.Outbox;
@@ -36,6 +37,7 @@ namespace PrivaPub.Services
 		readonly ILocalActorService _localActors;
 		readonly IRemoteActorService _remoteActors;
 		readonly IDeliveryService _delivery;
+		readonly IContentRenderer _content;
 		readonly IStringLocalizer<GenericRes> _localizer;
 		readonly ILogger<PostsService> _logger;
 
@@ -43,6 +45,7 @@ namespace PrivaPub.Services
 			ILocalActorService localActors,
 			IRemoteActorService remoteActors,
 			IDeliveryService delivery,
+			IContentRenderer content,
 			IStringLocalizer<GenericRes> localizer,
 			ILogger<PostsService> logger)
 		{
@@ -50,6 +53,7 @@ namespace PrivaPub.Services
 			_localActors = localActors;
 			_remoteActors = remoteActors;
 			_delivery = delivery;
+			_content = content;
 			_localizer = localizer;
 			_logger = logger;
 		}
@@ -76,6 +80,7 @@ namespace PrivaPub.Services
 				}
 
 				var parent = await Parent(form.AnsweringToPostId, token);
+				var rendered = await _content.Markdown(form.Text, token);
 				var post = new PostEntity
 				{
 					GroupUserId = author.Id,
@@ -84,8 +89,10 @@ namespace PrivaPub.Services
 					Visibility = isLocalOnly ? PostVisibility.Circle : PostVisibility.Public,
 					Title = form.Title,
 					Text = form.Text,
-					ContentHtml = ActivityPubRenderer.Html(form.Text),
+					ContentHtml = rendered.Html,
 					ContentFormat = ContentFormat.Markdown,
+					Mentions = rendered.Mentions.Select(ToMention).ToList(),
+					Tags = rendered.Tags.ToList(),
 					HasContentWarning = form.HasContentWarning,
 					AnsweringToPostId = parent?.ID,
 					InReplyToURI = parent?.ObjectURI ?? RemoteUri(form.AnsweringToPostId),
@@ -95,7 +102,7 @@ namespace PrivaPub.Services
 				};
 				post.ID = (string)post.GenerateNewID();
 				post.ObjectURI = author.PostUri(post.ID);
-				post.Url = post.ObjectURI;
+				post.Url = author.PostHtmlUrl(post.ID);
 
 				if (isLocalOnly)
 				{
@@ -113,7 +120,10 @@ namespace PrivaPub.Services
 				if (parent != default)
 					await DB.Default.Update<PostEntity>().MatchID(parent.ID).Modify(b => b.Inc(p => p.RepliesCount, 1)).ExecuteAsync(token);
 
-				await _delivery.EnqueueToFollowers(author, create, token);
+				var addressedInboxes = rendered.Mentions.Where(m => !m.IsLocal).Select(m => m.Inbox).ToList();
+				if (parent is { IsFederatedCopy: true } && !string.IsNullOrEmpty(parent.AuthorAccountId))
+					addressedInboxes.Add((await _dbEntities.ForeignAvatars.MatchID(parent.AuthorAccountId).ExecuteFirstAsync(token))?.InboxURL);
+				await _delivery.EnqueueToFollowers(author, create, token, addressedInboxes);
 				if (group != default)
 					await _delivery.EnqueueToFollowers(group, ActivityPubRenderer.Announce(group, post.ObjectURI, $"announce-{post.ID}"), token);
 
@@ -248,7 +258,7 @@ namespace PrivaPub.Services
 					{
 						dmGroup = new DmGroup { Members = members, ParticipantsKey = key };
 						dmGroup.ID = (string)dmGroup.GenerateNewID();
-						dmGroup.ConversationURI = $"{author.Uri}/conversations/{dmGroup.ID}";
+						dmGroup.ConversationURI = author.ConversationUri(dmGroup.ID);
 						await DB.Default.SaveAsync(dmGroup, token);
 					}
 				}
@@ -261,14 +271,14 @@ namespace PrivaPub.Services
 					Visibility = PostVisibility.Direct,
 					ContextURI = dmGroup.ConversationURI,
 					Text = form.Text,
-					ContentHtml = ActivityPubRenderer.Html(form.Text),
+					ContentHtml = (await _content.Markdown(form.Text, token)).Html,
 					ContentFormat = ContentFormat.Markdown,
 					HasContentWarning = form.HasContentWarning,
 					ActorURI = author.Uri
 				};
 				dm.ID = (string)dm.GenerateNewID();
 				dm.ObjectURI = author.PostUri(dm.ID);
-				dm.Url = dm.ObjectURI;
+				dm.Url = author.PostHtmlUrl(dm.ID);
 
 				var remote = new List<(string Uri, string Handle)>();
 				var inboxes = new List<string>();
@@ -377,6 +387,14 @@ namespace PrivaPub.Services
 				: await _dbEntities.Posts.MatchID(answeringTo).ExecuteFirstAsync(token);
 		}
 
+		static PostMention ToMention(ResolvedMention mention) => new()
+		{
+			ActorURI = mention.ActorUri,
+			Handle = "@" + mention.Handle,
+			IsLocal = mention.IsLocal,
+			AccountId = mention.AccountId
+		};
+
 		static string RemoteUri(string answeringTo) =>
 			answeringTo != default && answeringTo.StartsWith("https://", StringComparison.OrdinalIgnoreCase) ? answeringTo : default;