From 89eecd2bf74fd83708b5623e94591861db40b8ae Mon Sep 17 00:00:00 2001
From: timedout <git@nexy7574.co.uk>
Date: Mon, 21 Sep 2026 00:39:34 +0100
Subject: [PATCH] fix: Record `redacted_because_id` instead of
 `redacted_because`

---
 src/api/server/get_missing_events.rs |  4 ++--
 src/core/matrix/pdu/redact.rs        | 20 +++++++++++---------
 src/service/rooms/timeline/redact.rs |  2 +-
 3 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/src/api/server/get_missing_events.rs b/src/api/server/get_missing_events.rs
index a6578ac41..7c5b8799f 100644
--- a/src/api/server/get_missing_events.rs
+++ b/src/api/server/get_missing_events.rs
@@ -3,7 +3,7 @@ use std::collections::{HashSet, VecDeque};
 use axum::extract::State;
 use conduwuit::{Err, Event, Result, debug, info, trace, utils::to_canonical_object, warn};
 use ruma::{OwnedEventId, api::federation::event::get_missing_events};
-use serde_json::{json, value::RawValue};
+use serde_json::value::RawValue;
 use service::rooms::event_handler::GET_MISSING_EVENTS_MAX_BATCH_SIZE;
 
 use super::AccessCheck;
@@ -91,7 +91,7 @@ pub(crate) async fn get_missing_events_route(
 			.await
 		{
 			debug!(%next_event_id, origin = %body.identity, "redacting event origin cannot see");
-			pdu.redact(&room_version, json!({}))?;
+			pdu.redact(&room_version, None)?;
 		}
 
 		trace!(
diff --git a/src/core/matrix/pdu/redact.rs b/src/core/matrix/pdu/redact.rs
index ffee4fd49..875086563 100644
--- a/src/core/matrix/pdu/redact.rs
+++ b/src/core/matrix/pdu/redact.rs
@@ -1,10 +1,14 @@
 use ruma::{RoomVersionId, canonical_json::redact_content_in_place};
-use serde_json::{Value as JsonValue, json, value::to_raw_value};
+use serde_json::{json, value::to_raw_value};
 
 use crate::{Err, Result, err};
 
 impl super::Pdu {
-	pub fn redact(&mut self, room_version_id: &RoomVersionId, reason: JsonValue) -> Result {
+	pub fn redact(
+		&mut self,
+		room_version_id: &RoomVersionId,
+		redacted_because: Option<&ruma::EventId>,
+	) -> Result {
 		let Some(rules) = room_version_id.rules() else {
 			return Err!("Cannot redact event for unknown room version {room_version_id}");
 		};
@@ -20,15 +24,13 @@ impl super::Pdu {
 
 		redact_content_in_place(&mut content, &rules.redaction, self.kind.to_string());
 
-		let reason = serde_json::to_value(reason).expect("Failed to preserialize reason");
-
-		let redacted_because = json!({
-			"redacted_because": reason,
-		});
-
-		self.unsigned = to_raw_value(&redacted_because)
+		if let Some(event_id) = redacted_because {
+			self.unsigned = to_raw_value(&json!({
+				"redacted_because_id": event_id,
+			}))
 			.expect("Failed to serialize unsigned")
 			.into();
+		}
 
 		self.content = to_raw_value(&content).expect("Failed to serialize content");
 
diff --git a/src/service/rooms/timeline/redact.rs b/src/service/rooms/timeline/redact.rs
index 5509feeb5..efa19dff5 100644
--- a/src/service/rooms/timeline/redact.rs
+++ b/src/service/rooms/timeline/redact.rs
@@ -45,7 +45,7 @@ impl super::Service {
 			.get_room_version(&pdu.room_id_or_hash())
 			.await?;
 
-		pdu.redact(&room_version_id, reason.to_value())?;
+		pdu.redact(&room_version_id, Some(reason.event_id()))?;
 
 		let obj = utils::to_canonical_object(&pdu).map_err(|e| {
 			err!(Database(error!(%event_id, ?e, "Failed to convert PDU to canonical JSON")))