P6: quote posts, received and sent (FEP-044f and the older keys)

- Received quotes: read from `quote`, `quoteUrl`, `quoteUri`, `_misskey_quote` or a FEP-e232 Link tag; the quoted post
  is fetched once; a quoteAuthorization stamp is verified field by field on the quoted author's origin; a consent
  quote without a stamp is pending; an older-key quote of a public post is shown; Delete of a stamp revokes. Counts
  and a `quote` notification follow the accepted state. The `quote-inline` fallback survives sanitising and is removed
  from content when the real quote is shown.
- Personas quote through `quoted_status_id`: posts that state a quote policy get a QuoteRequest and stay pending until
  an Accept brings a stamp we can verify, then an Update adds quoteAuthorization; posts that state none are quoted
  the older way, without `quote`; another persona's posts cannot be quoted yet (we issue no stamps). Quoting posts
  are delivered to the quoted author too.
- Mastodon API: Status.quote (with the quoted status one level deep), quotes_count, quote_approval from the remote
  policy, GET /api/v1/statuses/:id/quotes, `quote` notifications, and api_versions.mastodon = 7.

Checked live: GoToSocial's author-only quote policy is respected.

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

PrivaPub/Federation/Inbox/Handlers/AcceptHandler.cs

@@ -1,5 +1,6 @@
 using MongoDB.Entities;
 
+using PrivaPub.Domain.Statuses;
 using PrivaPub.Federation.Actors;
 using PrivaPub.Models.Social;
 using PrivaPub.Models.User;
@@ -15,17 +16,21 @@ namespace PrivaPub.Federation.Inbox.Handlers
 	{
 		readonly DbEntities _dbEntities;
 		readonly ILocalActorService _localActors;
+		readonly IQuoteService _quotes;
 
-		public AcceptHandler(DbEntities dbEntities, ILocalActorService localActors)
+		public AcceptHandler(DbEntities dbEntities, ILocalActorService localActors, IQuoteService quotes)
 		{
 			_dbEntities = dbEntities;
 			_localActors = localActors;
+			_quotes = quotes;
 		}
 
 		public virtual string Type => "Accept";
 
 		public async Task Handle(JsonNode activity, ForeignAvatar actor, CancellationToken token)
 		{
+			if (await _quotes.Answered(activity, actor, accepted: Type == "Accept", token))
+				return;
 			var following = await FindFollowing(activity["object"], actor, _dbEntities, _localActors, token);
 			if (following == default)
 				return;
@@ -56,7 +61,7 @@ namespace PrivaPub.Federation.Inbox.Handlers
 
 	public class RejectHandler : AcceptHandler
 	{
-		public RejectHandler(DbEntities dbEntities, ILocalActorService localActors) : base(dbEntities, localActors)
+		public RejectHandler(DbEntities dbEntities, ILocalActorService localActors, IQuoteService quotes) : base(dbEntities, localActors, quotes)
 		{
 		}
 

PrivaPub/Federation/Inbox/Handlers/CreateHandler.cs

@@ -39,10 +39,12 @@ namespace PrivaPub.Federation.Inbox.Handlers
 		readonly IObjectRecords _records;
 		readonly IPollService _polls;
 		readonly ILinkPreviews _previews;
+		readonly IQuoteService _quotes;
 
 		public CreateHandler(DbEntities dbEntities, ILocalActorService localActors, IRemoteActorService remoteActors, IDeliveryService delivery,
-			IDomainBlocks domainBlocks, IFanout fanout, IRemotePosts remotePosts, IGroupDistributor groups, IObjectRecords records, IPollService polls, ILinkPreviews previews)
+			IDomainBlocks domainBlocks, IFanout fanout, IRemotePosts remotePosts, IGroupDistributor groups, IObjectRecords records, IPollService polls, ILinkPreviews previews, IQuoteService quotes)
 		{
+			_quotes = quotes;
 			_previews = previews;
 			_records = records;
 			_polls = polls;
@@ -152,6 +154,7 @@ namespace PrivaPub.Federation.Inbox.Handlers
 			}
 			await _records.Record(note, post, ObjectPath.Delivered, refetched, token);
 			await _previews.Wanted(post, token);
+			await _quotes.Resolve(post, note, token);
 
 			if (parent != default)
 				await DB.Default.Update<PostEntity>().MatchID(parent.ID).Modify(b => b.Inc(p => p.RepliesCount, 1)).ExecuteAsync(token);

PrivaPub/Federation/Inbox/Handlers/DeleteHandler.cs

@@ -1,5 +1,6 @@
 using MongoDB.Entities;
 
+using PrivaPub.Domain.Statuses;
 using PrivaPub.Federation.Actors;
 using PrivaPub.Federation.Objects;
 using PrivaPub.Federation.Outbox;
@@ -27,10 +28,12 @@ namespace PrivaPub.Federation.Inbox.Handlers
 		readonly IRemoteActorService _remoteActors;
 		readonly IDeliveryService _delivery;
 		readonly IGroupDistributor _groups;
+		readonly IQuoteService _quotes;
 
 		public DeleteHandler(DbEntities dbEntities, ILocalActorService localActors, IRemoteActorService remoteActors, IDeliveryService delivery,
-			IGroupDistributor groups)
+			IGroupDistributor groups, IQuoteService quotes)
 		{
+			_quotes = quotes;
 			_groups = groups;
 			_dbEntities = dbEntities;
 			_localActors = localActors;
@@ -72,7 +75,10 @@ namespace PrivaPub.Federation.Inbox.Handlers
 				.ExecuteAsync(token);
 			var post = await _dbEntities.Posts.Match(p => p.ObjectURI == objectUri && p.ActorURI == actor.ActorURI).ExecuteFirstAsync(token);
 			if (post == default)
+			{
+				await _quotes.Revoke(objectUri, token);
 				return;
+			}
 			await DB.Default.DeleteAsync<PostEntity>(post.ID);
 			await DB.Default.DeleteAsync<ObjectRecord>(r => r.PostId == post.ID || r.ObjectURI == objectUri);
 			await DB.Default.DeleteAsync<TimelineEntry>(e => e.PostId == post.ID || e.ReblogOfPostId == post.ID);

PrivaPub/Federation/Inbox/Handlers/UpdateHandler.cs

@@ -1,6 +1,7 @@
 using MongoDB.Entities;
 
 using PrivaPub.Federation.Actors;
+using PrivaPub.Domain.Statuses;
 using PrivaPub.Federation.Objects;
 using PrivaPub.Federation.Outbox;
 using PrivaPub.Models.Post;
@@ -24,10 +25,12 @@ namespace PrivaPub.Federation.Inbox.Handlers
 		readonly IRemoteActorService _remoteActors;
 		readonly IGroupDistributor _groups;
 		readonly IObjectRecords _records;
+		readonly IQuoteService _quotes;
 
 		public UpdateHandler(DbEntities dbEntities, ILocalActorService localActors, IRemoteActorService remoteActors, IGroupDistributor groups,
-			IObjectRecords records)
+			IObjectRecords records, IQuoteService quotes)
 		{
+			_quotes = quotes;
 			_records = records;
 			_groups = groups;
 			_dbEntities = dbEntities;
@@ -56,6 +59,7 @@ namespace PrivaPub.Federation.Inbox.Handlers
 				return;
 
 			post.Poll = note.Poll ?? post.Poll;
+			post.QuotePolicy = note.QuotePolicy;
 			post.Video = note.Video ?? post.Video;
 			post.Audio = note.Audio ?? post.Audio;
 			post.Event = note.Event ?? post.Event;
@@ -63,6 +67,7 @@ namespace PrivaPub.Federation.Inbox.Handlers
 			{
 				await DB.Default.SaveAsync(post, token);
 				await _records.Revise(note, Id(activity), token);
+				await Requote(post, note, token);
 				return;
 			}
 
@@ -102,11 +107,18 @@ namespace PrivaPub.Federation.Inbox.Handlers
 			post.UpdateDate = DateTime.UtcNow;
 			await DB.Default.SaveAsync(post, token);
 			await _records.Revise(note, Id(activity), token);
+			await Requote(post, note, token);
 			if (!string.IsNullOrEmpty(post.GroupId) && await _localActors.FindById(Models.Federation.LocalActorKind.Group, post.GroupId, token) is { IsCircle: false } community)
 				await _groups.Announce(community, activity.AsObject(), post.ObjectURI, isNewPost: false, token);
 		}
 
 		static bool IsEdit(NoteDocument note, PostEntity post) =>
 			note.Updated is { } updated && updated > (post.EditedAt ?? post.CreationDate);
+
+		async Task Requote(PostEntity post, NoteDocument note, CancellationToken token)
+		{
+			if (note.QuoteUri != post.QuoteURI || note.QuoteAuthorization != post.QuoteAuthorizationURI || post.QuoteState != QuoteState.Accepted)
+				await _quotes.Resolve(post, note, token);
+		}
 	}
 }

PrivaPub/Federation/Inbox/RemotePosts.cs

@@ -82,6 +82,7 @@ namespace PrivaPub.Federation.Inbox
 				Excerpt = note.Excerpt,
 				Source = note.Source,
 				Poll = note.Poll,
+				QuotePolicy = note.QuotePolicy,
 				Emojis = note.Emojis.ToList(),
 				CoverURL = note.CoverURL,
 				Link = note.Link,