P6 done: personas can be quoted, under the owner's default of anyone, automatically

- Our public and unlisted posts state interactionPolicy.canQuote. The policy comes from the post, then the persona
  (`source[quote_policy]`: public, followers or nobody; default public as the owner chose), and is always nobody for
  followers-only posts and DMs.
- QuoteRequests are answered with Accept{result} naming a parrot-licence at /peasants/{name}/parrot-licences/{id}
  (the route name the owner chose), or with Reject. Followers-only checks that the requester really follows.
- A licence is a QuoteAuthorization naming both posts; revoking it (POST /api/v1/statuses/:id/quotes/:quoting_id/revoke)
  marks it 410, sends Delete{licence} to the quoter and the persona's followers, and revokes our own copy of the quote.
- A quote that arrives with one of our licences is accepted only if that licence is ours, unrevoked and names exactly
  that quoting post. One persona quoting another gets a licence too.
- Mastodon API: quote_approval for our posts (automatic, followers, current_user), `quote_approval_policy` when posting,
  PUT /api/v1/statuses/:id/interaction_policy, `source.quote_policy`.

Checked live: GoToSocial still accepts our posts with the policy stated, and leaves likes, replies and boosts open.

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

PrivaPub/Federation/Controllers/PeasantsController.cs

@@ -199,6 +199,33 @@ namespace PrivaPub.Federation.Controllers
 			return Activity(note);
 		}
 
+		[HttpGet, Route("{actor}/parrot-licences/{licenceId}")]
+		public async Task<IActionResult> ParrotLicence(string actor, string licenceId, CancellationToken token)
+		{
+			var author = await _localActors.FindByUserName(actor, token);
+			var licence = author == default ? default : await DB.Default.Find<QuoteLicence>().Match(l => l.ID == licenceId && l.AuthorAvatarId == author.Id).ExecuteFirstAsync(token);
+			var quoted = licence == default ? default : await _dbEntities.Posts.MatchID(licence.PostId).ExecuteFirstAsync(token);
+			if (quoted == default)
+				return NotFound();
+			var uri = Domain.Statuses.QuoteService.LicenceUri(author, licence.ID);
+			if (licence.RevokedAt.HasValue || quoted.DeletedAt.HasValue)
+				return new ContentResult
+				{
+					Content = new JsonObject { ["@context"] = ActivityPubRenderer.ActivityStreams, ["id"] = uri, ["type"] = "Tombstone", ["formerType"] = "QuoteAuthorization" }.ToJsonString(),
+					ContentType = ActivityContentType,
+					StatusCode = StatusCodes.Status410Gone
+				};
+			return Activity(new JsonObject
+			{
+				["@context"] = ActivityPubRenderer.Context(),
+				["id"] = uri,
+				["type"] = "QuoteAuthorization",
+				["attributedTo"] = author.Uri,
+				["interactingObject"] = licence.QuotingObjectURI,
+				["interactionTarget"] = quoted.ObjectURI
+			});
+		}
+
 		[HttpGet, Route("{actor}/grunts/{activityId}")]
 		public async Task<IActionResult> Grunt(string actor, string activityId, CancellationToken token)
 		{

PrivaPub/Federation/Inbox/Handlers/QuoteRequestHandler.cs

@@ -0,0 +1,21 @@
+using PrivaPub.Domain.Statuses;
+using PrivaPub.Models.User;
+
+using System.Text.Json.Nodes;
+
+namespace PrivaPub.Federation.Inbox.Handlers
+{
+	public class QuoteRequestHandler : IActivityHandler
+	{
+		readonly IQuoteService _quotes;
+
+		public QuoteRequestHandler(IQuoteService quotes)
+		{
+			_quotes = quotes;
+		}
+
+		public string Type => "QuoteRequest";
+
+		public Task Handle(JsonNode activity, ForeignAvatar actor, CancellationToken token) => _quotes.ReceiveRequest(activity, actor, token);
+	}
+}

PrivaPub/Federation/Rendering/ActivityPubRenderer.cs

@@ -43,11 +43,18 @@ namespace PrivaPub.Federation.Rendering
 				["quoteAuthorization"] = new JsonObject { ["@id"] = "https://w3id.org/fep/044f#quoteAuthorization", ["@type"] = "@id" },
 				["QuoteRequest"] = "https://w3id.org/fep/044f#QuoteRequest",
 				["QuoteAuthorization"] = "https://w3id.org/fep/044f#QuoteAuthorization",
+				["interactingObject"] = new JsonObject { ["@id"] = "gts:interactingObject", ["@type"] = "@id" },
+				["interactionTarget"] = new JsonObject { ["@id"] = "gts:interactionTarget", ["@type"] = "@id" },
 				["misskey"] = "https://misskey-hub.net/ns#",
 				["_misskey_quote"] = "misskey:_misskey_quote",
 				["fedibird"] = "http://fedibird.com/ns#",
 				["quoteUri"] = "fedibird:quoteUri",
 				["quoteUrl"] = "as:quoteUrl",
+				["gts"] = "https://gotosocial.org/ns#",
+				["interactionPolicy"] = new JsonObject { ["@id"] = "gts:interactionPolicy", ["@type"] = "@id" },
+				["canQuote"] = new JsonObject { ["@id"] = "gts:canQuote", ["@type"] = "@id" },
+				["automaticApproval"] = new JsonObject { ["@id"] = "gts:automaticApproval", ["@type"] = "@id" },
+				["manualApproval"] = new JsonObject { ["@id"] = "gts:manualApproval", ["@type"] = "@id" },
 				["litepub"] = "http://litepub.social/ns#",
 				["EmojiReact"] = "litepub:EmojiReact",
 				["focalPoint"] = new JsonObject { ["@container"] = "@list", ["@id"] = "toot:focalPoint" },
@@ -188,6 +195,9 @@ namespace PrivaPub.Federation.Rendering
 			};
 		}
 
+		public static string QuotableBy(PostEntity post) =>
+			post.Visibility is PostVisibility.Public or PostVisibility.Unlisted ? post.LocalQuotePolicy ?? Models.User.QuotePolicies.Nobody : Models.User.QuotePolicies.Nobody;
+
 		static void AddQuote(JsonObject note, PostEntity post, ref string content)
 		{
 			if (string.IsNullOrEmpty(post.QuoteURI))
@@ -262,6 +272,19 @@ namespace PrivaPub.Federation.Rendering
 					.ToArray())
 			};
 			AddQuote(note, post, ref content);
+			if (!post.IsFederatedCopy)
+				note["interactionPolicy"] = new JsonObject
+				{
+					["canQuote"] = new JsonObject
+					{
+						["automaticApproval"] = new JsonArray((JsonNode)(QuotableBy(post) switch
+						{
+							Models.User.QuotePolicies.Public => Objects.Addressing.Public,
+							Models.User.QuotePolicies.Followers => author.Followers,
+							_ => author.Uri
+						}))
+					}
+				};
 			note["content"] = content;
 			if (!string.IsNullOrEmpty(post.Language))
 				note["contentMap"] = new JsonObject { [post.Language] = content };