From 3ab61615af14db54bfdbfe981de0aea21ccea414 Mon Sep 17 00:00:00 2001
From: Julian Lam <julian@nodebb.org>
Date: Mon, 1 Dec 2025 11:11:27 -0500
Subject: [PATCH] feat: federate out topic removal activities when topic is
 deleted and purged from a local category

---
 src/api/helpers.js | 14 +++++++++++++-
 src/api/topics.js  |  5 ++---
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/src/api/helpers.js b/src/api/helpers.js
index 3422b4a6f9..d7300f01e0 100644
--- a/src/api/helpers.js
+++ b/src/api/helpers.js
@@ -7,6 +7,7 @@ const posts = require('../posts');
 const privileges = require('../privileges');
 const plugins = require('../plugins');
 const activitypub = require('../activitypub');
+const utils = require('../utils');
 const socketHelpers = require('../socket.io/helpers');
 const websockets = require('../socket.io');
 const events = require('../events');
@@ -66,11 +67,22 @@ exports.doTopicAction = async function (action, event, caller, { tids }) {
 	const uids = await user.getUidsFromSet('users:online', 0, -1);
 
 	await Promise.all(tids.map(async (tid) => {
-		const title = await topics.getTopicField(tid, 'title');
+		const { title, cid, mainPid } = await topics.getTopicFields(tid, ['title', 'cid', 'mainPid']);
 		const data = await topics.tools[action](tid, caller.uid);
 		const notifyUids = await privileges.categories.filterUids('topics:read', data.cid, uids);
 		socketHelpers.emitToUids(event, data, notifyUids);
 		await logTopicAction(action, caller, tid, title);
+
+		switch(action) {
+			case 'delete': // falls through
+			case 'purge': {
+				if (utils.isNumber(cid) && parseInt(cid, 10) > 0) {
+					activitypub.out.remove.context(caller.uid, tid); // 7888-style
+					activitypub.out.delete.note(caller.uid, mainPid); // 1b12-style
+					activitypub.out.undo.announce('cid', cid, tid); // microblogs
+				}
+			}
+		}
 	}));
 };
 
diff --git a/src/api/topics.js b/src/api/topics.js
index 91e0882db4..88a260dd7c 100644
--- a/src/api/topics.js
+++ b/src/api/topics.js
@@ -324,13 +324,12 @@ topicsAPI.move = async (caller, { tid, cid }) => {
 
 				if (utils.isNumber(cid) && parseInt(cid, 10) === -1) {
 					activitypub.out.remove.context(caller.uid, tid); // 7888-style
-					activitypub.out.delete.note(caller.uid, topicData.mainPid); // threadiverse
-					// tbd: activitypubApi.undo.announce? // microblogs
+					activitypub.out.delete.note(caller.uid, topicData.mainPid); // 1b12-style
 				} else {
 					activitypub.out.move.context(caller.uid, tid);
 					activitypub.out.announce.topic(tid);
 				}
-				activitypub.out.undo.announce('cid', topicData.cid, tid);
+				activitypub.out.undo.announce('cid', topicData.cid, tid); // microblogs
 			}
 
 			await events.log({