From 6ba4b355262771d280ca6516d55357619e90cd08 Mon Sep 17 00:00:00 2001
From: Andy Balaam <andy.balaam@matrix.org>
Date: Tue, 7 Nov 2023 13:45:08 +0000
Subject: [PATCH] Revert "Revert "Don't remove thread info from a thread root
 when it is redacted""

This reverts commit 4dbff2a837cbc5ba37424c65ccdc833a1843deb2.
---
 spec/unit/models/event.spec.ts | 23 +++++++++++++++++++++++
 src/models/event.ts            |  5 +++--
 2 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/spec/unit/models/event.spec.ts b/spec/unit/models/event.spec.ts
index 9e7720a14..5ff9d745d 100644
--- a/spec/unit/models/event.spec.ts
+++ b/spec/unit/models/event.spec.ts
@@ -111,6 +111,29 @@ describe("MatrixEvent", () => {
             expect(mainTimelineLiveEventIds(room)).toEqual([ev.getId()]);
         });
 
+        it("should keep thread roots in both timelines when redacted", async () => {
+            // Given a thread exists
+            const mockClient = createMockClient();
+            const room = new Room("!roomid:e.xyz", mockClient, "myname");
+            const threadRoot = createEvent("$threadroot:server");
+            const ev = createThreadedEvent("$event1:server", threadRoot.getId()!);
+
+            await room.addLiveEvents([threadRoot, ev]);
+            await room.createThreadsTimelineSets();
+            expect(threadRoot.threadRootId).toEqual(threadRoot.getId());
+            expect(mainTimelineLiveEventIds(room)).toEqual([threadRoot.getId()]);
+            expect(threadLiveEventIds(room, 0)).toEqual([threadRoot.getId(), ev.getId()]);
+
+            // When I redact the thread root
+            const redaction = createRedaction(ev.getId()!);
+            threadRoot.makeRedacted(redaction, room);
+
+            // Then it remains in the main timeline and the thread
+            expect(threadRoot.threadRootId).toEqual(threadRoot.getId());
+            expect(mainTimelineLiveEventIds(room)).toEqual([threadRoot.getId()]);
+            expect(threadLiveEventIds(room, 0)).toEqual([threadRoot.getId(), ev.getId()]);
+        });
+
         it("should move into the main timeline when redacted", async () => {
             // Given an event in a thread
             const mockClient = createMockClient();
diff --git a/src/models/event.ts b/src/models/event.ts
index c76da4a45..d37c98b4a 100644
--- a/src/models/event.ts
+++ b/src/models/event.ts
@@ -1208,8 +1208,9 @@ export class MatrixEvent extends TypedEventEmitter<MatrixEventEmittedEvents, Mat
             }
         }
 
-        // If the redacted event was in a thread
-        if (room && this.threadRootId && this.threadRootId !== this.getId()) {
+        // If the redacted event was in a thread (but not thread root), move it
+        // to the main timeline. This will change if MSC3389 is merged.
+        if (room && !this.isThreadRoot && this.threadRootId && this.threadRootId !== this.getId()) {
             this.moveAllRelatedToMainTimeline(room);
         }