From 712c0c94874dedccecd061ae007a72370b1b65e9 Mon Sep 17 00:00:00 2001
From: dasha_uwu <dasha@linuxping.win>
Date: Tue, 27 Jan 2026 08:35:52 +0500
Subject: [PATCH] Do not overwrite retained PDU

---
 src/service/rooms/retention/mod.rs   | 18 +++++++++++++++++-
 src/service/rooms/timeline/append.rs |  5 +++--
 src/service/rooms/timeline/redact.rs |  6 ++++--
 3 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/src/service/rooms/retention/mod.rs b/src/service/rooms/retention/mod.rs
index e9c53640..3957fd10 100644
--- a/src/service/rooms/retention/mod.rs
+++ b/src/service/rooms/retention/mod.rs
@@ -10,6 +10,8 @@ use tuwunel_core::{
 };
 use tuwunel_database::{Deserialized, Json, Map};
 
+use crate::rooms::timeline::RoomMutexGuard;
+
 pub struct Service {
 	services: Arc<crate::services::OnceServices>,
 	eventid_originalpdu: Arc<Map>,
@@ -83,11 +85,25 @@ pub async fn get_original_pdu_json(&self, event_id: &EventId) -> Result<Canonica
 }
 
 #[implement(Service)]
-pub fn save_original_pdu(&self, event_id: &EventId, pdu: &CanonicalJsonObject) {
+pub async fn save_original_pdu(
+	&self,
+	event_id: &EventId,
+	pdu: &CanonicalJsonObject,
+	_state_lock: &RoomMutexGuard,
+) {
 	if !self.services.config.save_unredacted_events {
 		return;
 	}
 
+	if self
+		.eventid_originalpdu
+		.exists(event_id)
+		.await
+		.is_ok()
+	{
+		return;
+	}
+
 	let now = SystemTime::now()
 		.duration_since(UNIX_EPOCH)
 		.unwrap()
diff --git a/src/service/rooms/timeline/append.rs b/src/service/rooms/timeline/append.rs
index c81c321d..74e0bc4d 100644
--- a/src/service/rooms/timeline/append.rs
+++ b/src/service/rooms/timeline/append.rs
@@ -184,7 +184,7 @@ where
 		.log_err()
 		.ok();
 
-	self.append_pdu_effects(pdu_id, pdu, shortroomid, count)
+	self.append_pdu_effects(pdu_id, pdu, shortroomid, count, state_lock)
 		.await?;
 
 	drop(next_count1);
@@ -207,6 +207,7 @@ async fn append_pdu_effects(
 	pdu: &PduEvent,
 	shortroomid: ShortRoomId,
 	count: PduCount,
+	state_lock: &RoomMutexGuard,
 ) -> Result {
 	match *pdu.kind() {
 		| TimelineEventType::RoomRedaction => {
@@ -233,7 +234,7 @@ async fn append_pdu_effects(
 					.user_can_redact(redact_id, pdu.sender(), pdu.room_id(), false)
 					.await?
 			{
-				self.redact_pdu(redact_id, pdu, shortroomid)
+				self.redact_pdu(redact_id, pdu, shortroomid, state_lock)
 					.await?;
 			}
 		},
diff --git a/src/service/rooms/timeline/redact.rs b/src/service/rooms/timeline/redact.rs
index 3632c1e9..16c6fde4 100644
--- a/src/service/rooms/timeline/redact.rs
+++ b/src/service/rooms/timeline/redact.rs
@@ -4,7 +4,7 @@ use ruma::{
 };
 use tuwunel_core::{Result, err, implement, matrix::event::Event};
 
-use crate::rooms::short::ShortRoomId;
+use crate::rooms::{short::ShortRoomId, timeline::RoomMutexGuard};
 
 /// Replace a PDU with the redacted form.
 #[implement(super::Service)]
@@ -14,6 +14,7 @@ pub async fn redact_pdu<Pdu: Event + Send + Sync>(
 	event_id: &EventId,
 	reason: &Pdu,
 	shortroomid: ShortRoomId,
+	state_lock: &RoomMutexGuard,
 ) -> Result {
 	let Ok(pdu_id) = self.get_pdu_id(event_id).await else {
 		// If event does not exist, just noop
@@ -30,7 +31,8 @@ pub async fn redact_pdu<Pdu: Event + Send + Sync>(
 
 	self.services
 		.retention
-		.save_original_pdu(event_id, &pdu);
+		.save_original_pdu(event_id, &pdu, state_lock)
+		.await;
 
 	let body = pdu["content"]
 		.as_object()