From 0c79eaa529e7f0265f0cd5339a305593f1292f61 Mon Sep 17 00:00:00 2001
From: Julian Lam <julian@nodebb.org>
Date: Mon, 19 Jan 2026 19:06:23 -0500
Subject: [PATCH] feat: topic crossposts generate topic events, #13908

---
 public/language/en-GB/topic.json |  2 ++
 src/topics/crossposts.js         |  7 ++++++-
 src/topics/events.js             | 14 +++++++++++++-
 3 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/public/language/en-GB/topic.json b/public/language/en-GB/topic.json
index f736000fb9..7b0979f70b 100644
--- a/public/language/en-GB/topic.json
+++ b/public/language/en-GB/topic.json
@@ -74,6 +74,8 @@
 	"user-referenced-topic-on": "%1 <a href=\"%2\">referenced</a> this topic on %3",
 	"user-forked-topic-ago": "%1 <a href=\"%2\">forked</a> this topic %3",
 	"user-forked-topic-on": "%1 <a href=\"%2\">forked</a> this topic on %3",
+	"user-crossposted-topic-ago": "%1 crossposted this topic to %2 %3",
+	"user-crossposted-topic-on": "%1 crossposted this topicto %2 on %3",
 
 	"bookmark-instructions" : "Click here to return to the last read post in this thread.",
 
diff --git a/src/topics/crossposts.js b/src/topics/crossposts.js
index e677e11481..0bd2f918af 100644
--- a/src/topics/crossposts.js
+++ b/src/topics/crossposts.js
@@ -98,8 +98,9 @@ Crossposts.add = async function (tid, cid, uid) {
 			db.setObject(`crosspost:${crosspostId}`, { uid, tid, cid, timestamp: now }),
 			db.sortedSetAdd(`tid:${tid}:crossposts`, now, crosspostId),
 			uid > 0 ? db.sortedSetAdd(`uid:${uid}:crossposts`, now, crosspostId) : false,
+			topics.events.log(tid, { uid, type: 'crosspost', toCid: cid }),
 		]);
-		await categories.onTopicsMoved([cid]);
+		await categories.onTopicsMoved([cid]); // must be done after
 	} else {
 		throw new Error('[[error:topic-already-crossposted]]');
 	}
@@ -146,6 +147,10 @@ Crossposts.remove = async function (tid, cid, uid) {
 	]);
 	await categories.onTopicsMoved([cid]);
 
+	topics.events.find(tid, { uid, toCid: cid, type: 'crosspost' }).then((eventIds) => {
+		topics.events.purge(tid, eventIds);
+	});
+
 	crossposts = await Crossposts.get(tid);
 	return crossposts;
 };
diff --git a/src/topics/events.js b/src/topics/events.js
index 0748318c37..87d81b3100 100644
--- a/src/topics/events.js
+++ b/src/topics/events.js
@@ -73,6 +73,10 @@ Events._types = {
 		icon: 'fa-code-fork',
 		translation: async (event, language) => translateEventArgs(event, language, 'topic:user-forked-topic', renderUser(event), `${relative_path}${event.href}`, renderTimeago(event)),
 	},
+	crosspost: {
+		icon: 'fa-square-arrow-up-right',
+		translation: async (event, language) => translateEventArgs(event, language, 'topic:user-crossposted-topic', renderUser(event), renderCategory(event.toCategory), renderTimeago(event)),
+	},
 };
 
 Events.init = async () => {
@@ -117,6 +121,10 @@ function renderUser(event) {
 	return `${helpers.buildAvatar(user, '16px', true)} <a href="${relative_path}/user/${user.userslug}">${user.displayname}</a>`;
 }
 
+function renderCategory(category) {
+	return `${helpers.buildCategoryLabel(category, 'a')}`;
+}
+
 function renderTimeago(event) {
 	return `<span class="timeago timeline-text" title="${event.timestampISO}"></span>`;
 }
@@ -183,9 +191,10 @@ async function addEventsFromPostQueue(tid, uid, events) {
 }
 
 async function modifyEvent({ uid, events }) {
-	const [users, fromCategories, userSettings] = await Promise.all([
+	const [users, fromCategories, toCategories, userSettings] = await Promise.all([
 		getUserInfo(events.map(event => event.uid).filter(Boolean)),
 		getCategoryInfo(events.map(event => event.fromCid).filter(Boolean)),
+		getCategoryInfo(events.map(event => event.toCid).filter(Boolean)),
 		user.getSettings(uid),
 	]);
 
@@ -215,6 +224,9 @@ async function modifyEvent({ uid, events }) {
 		if (event.hasOwnProperty('fromCid')) {
 			event.fromCategory = fromCategories[event.fromCid];
 		}
+		if (event.hasOwnProperty('toCid')) {
+			event.toCategory = toCategories[event.toCid];
+		}
 
 		Object.assign(event, Events._types[event.type]);
 	});