From f6cc556d37bd2289709b79f9dd70212b8656342e Mon Sep 17 00:00:00 2001
From: Julian Lam <julian@nodebb.org>
Date: Mon, 29 Dec 2025 14:32:34 -0500
Subject: [PATCH] fix: topic crosspost delete and purge handling

---
 src/topics/crossposts.js  | 10 +++++++
 src/topics/delete.js      |  1 +
 test/topics/crossposts.js | 60 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 71 insertions(+)

diff --git a/src/topics/crossposts.js b/src/topics/crossposts.js
index ce2bcda93a..72cff44424 100644
--- a/src/topics/crossposts.js
+++ b/src/topics/crossposts.js
@@ -127,4 +127,14 @@ Crossposts.remove = async function (tid, cid, uid) {
 
 	crossposts = await Crossposts.get(tid);
 	return crossposts;
+};
+
+Crossposts.removeAll = async function (tid) {
+	const crosspostIds = await db.getSortedSetMembers(`tid:${tid}:crossposts`);
+	const crossposts = await db.getObjects(crosspostIds.map(id => `crosspost:${id}`));
+	await Promise.all(crossposts.map(async ({ tid, cid, uid }) => {
+		return Crossposts.remove(tid, cid, uid);
+	}));
+
+	return [];
 };
\ No newline at end of file
diff --git a/src/topics/delete.js b/src/topics/delete.js
index 466d25a0dd..03e756e1fd 100644
--- a/src/topics/delete.js
+++ b/src/topics/delete.js
@@ -102,6 +102,7 @@ module.exports = function (Topics) {
 			Topics.deleteTopicTags(tid),
 			Topics.events.purge(tid),
 			Topics.thumbs.deleteAll(tid),
+			Topics.crossposts.removeAll(tid),
 			reduceCounters(tid),
 		]);
 		plugins.hooks.fire('action:topic.purge', { topic: deletedTopic, uid: uid });
diff --git a/test/topics/crossposts.js b/test/topics/crossposts.js
index a018973a50..542e5b22a7 100644
--- a/test/topics/crossposts.js
+++ b/test/topics/crossposts.js
@@ -288,6 +288,66 @@ describe('Crossposting (& related logic)', () => {
 		});
 	});
 
+	describe('Deletion', () => {
+		let tid;
+		let cid1;
+		let cid2;
+		let uid;
+
+		before(async () => {
+			({ cid: cid1 } = await categories.create({ name: utils.generateUUID().slice(0, 8) }));
+			const crosspostCategory = await categories.create({ name: utils.generateUUID().slice(0, 8) });
+			cid2 = crosspostCategory.cid;
+			uid = await user.create({ username: utils.generateUUID().slice(0, 8) });
+			const { topicData } = await topics.post({
+				uid,
+				cid: cid1,
+				title: utils.generateUUID(),
+				content: utils.generateUUID(),
+			});
+			tid = topicData.tid;
+
+			await topics.crossposts.add(tid, cid2, uid);
+			await topics.delete(tid, uid);
+		});
+
+		it('should maintain crossposts when topic is deleted', async () => {
+			const crossposts = await topics.crossposts.get(tid);
+			assert(Array.isArray(crossposts));
+			assert.strictEqual(crossposts.length, 1);
+		});
+	});
+
+	describe('Purging', () => {
+		let tid;
+		let cid1;
+		let cid2;
+		let uid;
+
+		before(async () => {
+			({ cid: cid1 } = await categories.create({ name: utils.generateUUID().slice(0, 8) }));
+			const crosspostCategory = await categories.create({ name: utils.generateUUID().slice(0, 8) });
+			cid2 = crosspostCategory.cid;
+			uid = await user.create({ username: utils.generateUUID().slice(0, 8) });
+			const { topicData } = await topics.post({
+				uid,
+				cid: cid1,
+				title: utils.generateUUID(),
+				content: utils.generateUUID(),
+			});
+			tid = topicData.tid;
+
+			await topics.crossposts.add(tid, cid2, uid);
+			await topics.purge(tid, uid);
+		});
+
+		it('should remove crossposts when topic is purged', async () => {
+			const crossposts = await topics.crossposts.get(tid);
+			assert(Array.isArray(crossposts));
+			assert.strictEqual(crossposts.length, 0);
+		});
+	});
+
 	describe('ActivityPub effects (or lack thereof)', () => {
 		describe('local canonical category', () => {
 			let tid;