fix: Filter out invalid replacements from bundled aggregations

Add support for the m.replace and m.reference bundled
aggregations.
This should fix plenty of subtle client issues.
Threads are not included in the new code as they have
historically been written to the database. Replacing the
old system would result in issues when switching away from
continuwuity, so saved for later.
Some TODOs have been left re event visibility and ignored users.
These should be OK for now, though.

.forgejo/workflows/release-image.yml

@@ -180,7 +180,7 @@ jobs:
           file: "docker/Dockerfile"
           build-args: |
             GIT_COMMIT_HASH=${{ github.sha }})
-            GIT_COMMIT_HASH_SHORT=${{ env.COMMIT_SHORT_SHA }})
+            GIT_COMMIT_HASH_SHORT=${{ env.COMMIT_SHORT_SHA }}
             GIT_REMOTE_URL=${{github.event.repository.html_url }}
             GIT_REMOTE_COMMIT_URL=${{github.event.head_commit.url }}
           platforms: ${{ matrix.platform }}

SECURITY.md

@@ -20,10 +20,10 @@ We may backport fixes to the previous release at our discretion, but we don't gu
 
 We appreciate the efforts of security researchers and the community in identifying and reporting vulnerabilities. To ensure that potential vulnerabilities are addressed properly, please follow these guidelines:
 
-1. Contact members of the team over E2EE private message.
+1. **Contact members of the team directly** over E2EE private message.
    - [@jade:ellis.link](https://matrix.to/#/@jade:ellis.link)
    - [@nex:nexy7574.co.uk](https://matrix.to/#/@nex:nexy7574.co.uk) <!-- ? -->
-2. **Email the security team** directly at [security@continuwuity.org](mailto:security@continuwuity.org). This is not E2EE, so don't include sensitive details.
+2. **Email the security team** at [security@continuwuity.org](mailto:security@continuwuity.org). This is not E2EE, so don't include sensitive details.
 3. **Do not disclose the vulnerability publicly** until it has been addressed
 4. **Provide detailed information** about the vulnerability, including:
    - A clear description of the issue
@@ -48,7 +48,7 @@ When you report a security vulnerability:
 
 When security vulnerabilities are identified:
 
-1. We will develop and test fixes in a private branch
+1. We will develop and test fixes in a private fork
 2. Security updates will be released as soon as possible
 3. Release notes will include information about the vulnerabilities, avoiding details that could facilitate exploitation where possible
 4. Critical security updates may be backported to the previous stable release

src/admin/debug/mod.rs

@@ -125,13 +125,13 @@ pub(super) enum DebugCommand {
 		reset: bool,
 	},
 
-	/// - Verify json signatures
+	/// - Sign JSON blob
 	///
 	/// This command needs a JSON blob provided in a Markdown code block below
 	/// the command.
 	SignJson,
 
-	/// - Verify json signatures
+	/// - Verify JSON signatures
 	///
 	/// This command needs a JSON blob provided in a Markdown code block below
 	/// the command.

src/admin/query/room_timeline.rs

@@ -31,7 +31,7 @@ pub(super) async fn last(&self, room_id: OwnedRoomOrAliasId) -> Result {
 		.services
 		.rooms
 		.timeline
-		.last_timeline_count(None, &room_id)
+		.last_timeline_count(&room_id)
 		.await?;
 
 	self.write_str(&format!("{result:#?}")).await
@@ -52,7 +52,7 @@ pub(super) async fn pdus(
 		.services
 		.rooms
 		.timeline
-		.pdus_rev(None, &room_id, from)
+		.pdus_rev(&room_id, from)
 		.try_take(limit.unwrap_or(3))
 		.try_collect()
 		.await?;

src/api/client/context.rs

@@ -84,11 +84,25 @@ pub(crate) async fn get_context_route(
 
 	let base_event = ignored_filter(&services, (base_count, base_pdu), sender_user);
 
+	// PDUs are used to get seen user IDs and then returned in response.
+
 	let events_before = services
 		.rooms
 		.timeline
-		.pdus_rev(Some(sender_user), room_id, Some(base_count))
+		.pdus_rev(room_id, Some(base_count))
 		.ignore_err()
+		.then(async |mut pdu| {
+			pdu.1.set_unsigned(Some(sender_user));
+			if let Err(e) = services
+				.rooms
+				.pdu_metadata
+				.add_bundled_aggregations_to_pdu(sender_user, &mut pdu.1)
+				.await
+			{
+				debug_warn!("Failed to add bundled aggregations: {e}");
+			}
+			pdu
+		})
 		.ready_filter_map(|item| event_filter(item, filter))
 		.wide_filter_map(|item| ignored_filter(&services, item, sender_user))
 		.wide_filter_map(|item| visibility_filter(&services, item, sender_user))
@@ -98,8 +112,20 @@ pub(crate) async fn get_context_route(
 	let events_after = services
 		.rooms
 		.timeline
-		.pdus(Some(sender_user), room_id, Some(base_count))
+		.pdus(room_id, Some(base_count))
 		.ignore_err()
+		.then(async |mut pdu| {
+			pdu.1.set_unsigned(Some(sender_user));
+			if let Err(e) = services
+				.rooms
+				.pdu_metadata
+				.add_bundled_aggregations_to_pdu(sender_user, &mut pdu.1)
+				.await
+			{
+				debug_warn!("Failed to add bundled aggregations: {e}");
+			}
+			pdu
+		})
 		.ready_filter_map(|item| event_filter(item, filter))
 		.wide_filter_map(|item| ignored_filter(&services, item, sender_user))
 		.wide_filter_map(|item| visibility_filter(&services, item, sender_user))

src/api/client/message.rs

@@ -2,7 +2,7 @@ use core::panic;
 
 use axum::extract::State;
 use conduwuit::{
-	Err, Result, at,
+	Err, Result, at, debug_warn,
 	matrix::{
 		Event,
 		pdu::{PduCount, PduEvent},
@@ -114,14 +114,14 @@ pub(crate) async fn get_message_events_route(
 		| Direction::Forward => services
 			.rooms
 			.timeline
-			.pdus(Some(sender_user), room_id, Some(from))
+			.pdus(room_id, Some(from))
 			.ignore_err()
 			.boxed(),
 
 		| Direction::Backward => services
 			.rooms
 			.timeline
-			.pdus_rev(Some(sender_user), room_id, Some(from))
+			.pdus_rev(room_id, Some(from))
 			.ignore_err()
 			.boxed(),
 	};
@@ -132,6 +132,18 @@ pub(crate) async fn get_message_events_route(
 		.wide_filter_map(|item| ignored_filter(&services, item, sender_user))
 		.wide_filter_map(|item| visibility_filter(&services, item, sender_user))
 		.take(limit)
+		.then(async |mut pdu| {
+			pdu.1.set_unsigned(Some(sender_user));
+			if let Err(e) = services
+				.rooms
+				.pdu_metadata
+				.add_bundled_aggregations_to_pdu(sender_user, &mut pdu.1)
+				.await
+			{
+				debug_warn!("Failed to add bundled aggregations: {e}");
+			}
+			pdu
+		})
 		.collect()
 		.await;
 

src/api/client/relations.rs

@@ -1,6 +1,6 @@
 use axum::extract::State;
 use conduwuit::{
-	Result, at,
+	Result, at, debug_warn,
 	matrix::pdu::PduCount,
 	utils::{IterStream, ReadyExt, result::FlatOk, stream::WidebandExt},
 };
@@ -149,6 +149,17 @@ async fn paginate_relations_with_filter(
 		.ready_take_while(|(count, _)| Some(*count) != to)
 		.wide_filter_map(|item| visibility_filter(services, sender_user, item))
 		.take(limit)
+		.then(async |mut pdu| {
+			if let Err(e) = services
+				.rooms
+				.pdu_metadata
+				.add_bundled_aggregations_to_pdu(sender_user, &mut pdu.1)
+				.await
+			{
+				debug_warn!("Failed to add bundled aggregations to relation: {e}");
+			}
+			pdu
+		})
 		.collect()
 		.await;
 
@@ -172,6 +183,10 @@ async fn paginate_relations_with_filter(
 	})
 }
 
+// TODO: Can we move the visibility filter lower down, to avoid checking events
+// that won't be sent? At the moment this also results in getting events that
+// appear to have no relation because intermediaries are not visible to the
+// user.
 async fn visibility_filter(
 	services: &Services,
 	sender_user: &UserId,

src/api/client/room/event.rs

@@ -1,5 +1,5 @@
 use axum::extract::State;
-use conduwuit::{Err, Event, Result, err};
+use conduwuit::{Err, Event, Result, debug_warn, err};
 use futures::{FutureExt, TryFutureExt, future::try_join};
 use ruma::api::client::room::get_room_event;
 
@@ -38,7 +38,16 @@ pub(crate) async fn get_room_event_route(
 		"Fetched PDU must match requested"
 	);
 
-	event.add_age().ok();
+	if let Err(e) = services
+		.rooms
+		.pdu_metadata
+		.add_bundled_aggregations_to_pdu(body.sender_user(), &mut event)
+		.await
+	{
+		debug_warn!("Failed to add bundled aggregations to event: {e}");
+	}
+
+	event.set_unsigned(body.sender_user.as_deref());
 
 	Ok(get_room_event::v3::Response { event: event.into_room_event() })
 }

src/api/client/room/initial_sync.rs

@@ -1,6 +1,6 @@
 use axum::extract::State;
 use conduwuit::{
-	Err, PduEvent, Result, at,
+	Err, PduEvent, Result, at, debug_warn,
 	utils::{BoolExt, stream::TryTools},
 };
 use futures::TryStreamExt;
@@ -25,12 +25,28 @@ pub(crate) async fn room_initial_sync_route(
 		return Err!(Request(Forbidden("No room preview available.")));
 	}
 
+	// Events are returned in body
+
 	let limit = LIMIT_MAX;
 	let events: Vec<_> = services
 		.rooms
 		.timeline
-		.pdus_rev(None, room_id, None)
+		.pdus_rev(room_id, None)
 		.try_take(limit)
+		.and_then(async |mut pdu| {
+			pdu.1.set_unsigned(body.sender_user.as_deref());
+			if let Some(sender_user) = body.sender_user.as_deref() {
+				if let Err(e) = services
+					.rooms
+					.pdu_metadata
+					.add_bundled_aggregations_to_pdu(sender_user, &mut pdu.1)
+					.await
+				{
+					debug_warn!("Failed to add bundled aggregations: {e}");
+				}
+			}
+			Ok(pdu)
+		})
 		.try_collect()
 		.await?;
 

src/api/client/search.rs

@@ -2,7 +2,7 @@ use std::collections::BTreeMap;
 
 use axum::extract::State;
 use conduwuit::{
-	Err, Result, at, is_true,
+	Err, Result, at, debug_warn, is_true,
 	matrix::pdu::PduEvent,
 	result::FlatOk,
 	utils::{IterStream, stream::ReadyExt},
@@ -144,6 +144,17 @@ async fn category_room_events(
 		.map(at!(2))
 		.flatten()
 		.stream()
+		.then(|mut pdu| async {
+			if let Err(e) = services
+				.rooms
+				.pdu_metadata
+				.add_bundled_aggregations_to_pdu(sender_user, &mut pdu)
+				.await
+			{
+				debug_warn!("Failed to add bundled aggregations to search result: {e}");
+			}
+			pdu
+		})
 		.map(PduEvent::into_room_event)
 		.map(|result| SearchResult {
 			rank: None,

src/api/client/sync/mod.rs

@@ -3,7 +3,7 @@ mod v4;
 mod v5;
 
 use conduwuit::{
-	Error, PduCount, Result,
+	Error, PduCount, Result, debug_warn,
 	matrix::pdu::PduEvent,
 	utils::stream::{BroadbandExt, ReadyExt, TryIgnore},
 };
@@ -31,11 +31,7 @@ async fn load_timeline(
 	next_batch: Option<PduCount>,
 	limit: usize,
 ) -> Result<(Vec<(PduCount, PduEvent)>, bool), Error> {
-	let last_timeline_count = services
-		.rooms
-		.timeline
-		.last_timeline_count(Some(sender_user), room_id)
-		.await?;
+	let last_timeline_count = services.rooms.timeline.last_timeline_count(room_id).await?;
 
 	if last_timeline_count <= roomsincecount {
 		return Ok((Vec::new(), false));
@@ -44,10 +40,25 @@ async fn load_timeline(
 	let non_timeline_pdus = services
 		.rooms
 		.timeline
-		.pdus_rev(Some(sender_user), room_id, None)
+		.pdus_rev(room_id, None)
 		.ignore_err()
 		.ready_skip_while(|&(pducount, _)| pducount > next_batch.unwrap_or_else(PduCount::max))
-		.ready_take_while(|&(pducount, _)| pducount > roomsincecount);
+		.ready_take_while(|&(pducount, _)| pducount > roomsincecount)
+		.map(move |mut pdu| {
+			pdu.1.set_unsigned(Some(sender_user));
+			pdu
+		})
+		.then(async move |mut pdu| {
+			if let Err(e) = services
+				.rooms
+				.pdu_metadata
+				.add_bundled_aggregations_to_pdu(sender_user, &mut pdu.1)
+				.await
+			{
+				debug_warn!("Failed to add bundled aggregations: {e}");
+			}
+			pdu
+		});
 
 	// Take the last events for the timeline
 	pin_mut!(non_timeline_pdus);

src/api/client/sync/v3.rs

@@ -1191,7 +1191,7 @@ async fn calculate_heroes(
 	services
 		.rooms
 		.timeline
-		.all_pdus(sender_user, room_id)
+		.all_pdus(room_id)
 		.ready_filter(|(_, pdu)| pdu.kind == RoomMember)
 		.fold_default(|heroes: Vec<_>, (_, pdu)| {
 			fold_hero(heroes, services, room_id, sender_user, pdu)

src/api/client/threads.rs

@@ -1,6 +1,6 @@
 use axum::extract::State;
 use conduwuit::{
-	Result, at,
+	Result, at, debug_warn,
 	matrix::pdu::{PduCount, PduEvent},
 };
 use futures::StreamExt;
@@ -28,6 +28,8 @@ pub(crate) async fn get_threads_route(
 		.transpose()?
 		.unwrap_or_else(PduCount::max);
 
+	// TODO: user_can_see_event and set_unsigned should be at the same level /
+	// function, so unsigned is only set for seen events.
 	let threads: Vec<(PduCount, PduEvent)> = services
 		.rooms
 		.threads
@@ -42,6 +44,17 @@ pub(crate) async fn get_threads_route(
 				.await
 				.then_some((count, pdu))
 		})
+		.then(|(count, mut pdu)| async move {
+			if let Err(e) = services
+				.rooms
+				.pdu_metadata
+				.add_bundled_aggregations_to_pdu(body.sender_user(), &mut pdu)
+				.await
+			{
+				debug_warn!("Failed to add bundled aggregations to thread: {e}");
+			}
+			(count, pdu)
+		})
 		.collect()
 		.await;
 

src/api/server/backfill.rs

@@ -3,6 +3,7 @@ use std::cmp;
 use axum::extract::State;
 use conduwuit::{
 	PduCount, Result,
+	result::LogErr,
 	utils::{IterStream, ReadyExt, stream::TryTools},
 };
 use futures::{FutureExt, StreamExt, TryStreamExt};
@@ -62,7 +63,7 @@ pub(crate) async fn get_backfill_route(
 		pdus: services
 			.rooms
 			.timeline
-			.pdus_rev(None, &body.room_id, Some(from.saturating_add(1)))
+			.pdus_rev(&body.room_id, Some(from.saturating_add(1)))
 			.try_take(limit)
 			.try_filter_map(|(_, pdu)| async move {
 				Ok(services
@@ -72,6 +73,15 @@ pub(crate) async fn get_backfill_route(
 					.await
 					.then_some(pdu))
 			})
+			.and_then(async |mut pdu| {
+				// Strip the transaction ID, as that is private
+				pdu.remove_transaction_id().log_err().ok();
+				// Add age, as this is specified
+				pdu.add_age().log_err().ok();
+				// It's not clear if we should strip or add any more data, leave as is.
+				// In particular: Redaction?
+				Ok(pdu)
+			})
 			.try_filter_map(|pdu| async move {
 				Ok(services
 					.rooms

src/core/config/check.rs

@@ -219,6 +219,15 @@ pub fn check(config: &Config) -> Result {
 		));
 	}
 
+	// Check if support contact information is configured
+	if config.well_known.support_email.is_none() && config.well_known.support_mxid.is_none() {
+		warn!(
+			"No support contact information (support_email or support_mxid) is configured in \
+			 the well_known section. Users in the admin room will be automatically listed as \
+			 support contacts in the /.well-known/matrix/support endpoint."
+		);
+	}
+
 	if config
 		.url_preview_domain_contains_allowlist
 		.contains(&"*".to_owned())

src/core/matrix/pdu/unsigned.rs

@@ -1,11 +1,24 @@
-use std::collections::BTreeMap;
+use std::{borrow::Borrow, collections::BTreeMap};
 
 use ruma::MilliSecondsSinceUnixEpoch;
 use serde::Deserialize;
 use serde_json::value::{RawValue as RawJsonValue, Value as JsonValue, to_raw_value};
 
 use super::Pdu;
-use crate::{Result, err, implement, is_true};
+use crate::{Result, err, implement, is_true, result::LogErr};
+
+/// Set the `unsigned` field of the PDU using only information in the PDU.
+/// Some unsigned data is already set within the database (eg. prev events,
+/// threads). Once this is done, other data must be calculated from the database
+/// (eg. relations) This is for server-to-client events.
+/// Backfill handles this itself.
+#[implement(Pdu)]
+pub fn set_unsigned(&mut self, user_id: Option<&ruma::UserId>) {
+	if Some(self.sender.borrow()) != user_id {
+		self.remove_transaction_id().log_err().ok();
+	}
+	self.add_age().log_err().ok();
+}
 
 #[implement(Pdu)]
 pub fn remove_transaction_id(&mut self) -> Result {

src/service/rooms/pdu_metadata/bundled_aggregations.rs

@@ -0,0 +1,765 @@
+use conduwuit::{Event, PduEvent, Result, err};
+use ruma::{
+	EventId, RoomId, UserId,
+	api::Direction,
+	events::relation::{BundledMessageLikeRelations, BundledReference, ReferenceChunk},
+};
+
+use super::PdusIterItem;
+
+const MAX_BUNDLED_RELATIONS: usize = 50;
+
+impl super::Service {
+	/// Gets bundled aggregations for an event according to the Matrix
+	/// specification.
+	/// - m.replace relations are bundled to include the most recent replacement
+	///   event.
+	/// - m.reference relations are bundled to include a chunk of event IDs.
+	#[tracing::instrument(skip(self), level = "debug")]
+	pub async fn get_bundled_aggregations(
+		&self,
+		user_id: &UserId,
+		room_id: &RoomId,
+		event_id: &EventId,
+	) -> Result<Option<BundledMessageLikeRelations<Box<serde_json::value::RawValue>>>> {
+		let relations = self
+			.get_relations(
+				user_id,
+				room_id,
+				event_id,
+				conduwuit::PduCount::max(),
+				MAX_BUNDLED_RELATIONS,
+				0,
+				Direction::Backward,
+			)
+			.await;
+		// The relations database code still handles the basic unsigned data
+		// We don't want to recursively fetch relations
+
+		// TODO: Event visibility check
+		// TODO: ignored users?
+
+		if relations.is_empty() {
+			return Ok(None);
+		}
+
+		// Get the original event for validation of replacement events
+		let original_event = self.services.timeline.get_pdu(event_id).await?;
+
+		let mut replace_events = Vec::with_capacity(relations.len());
+		let mut reference_events = Vec::with_capacity(relations.len());
+
+		for relation in &relations {
+			let pdu = &relation.1;
+
+			let content = pdu.get_content_as_value();
+			if let Some(relates_to) = content.get("m.relates_to") {
+				// We don't check that the event relates back, because we assume the database is
+				// good.
+				if let Some(rel_type) = relates_to.get("rel_type") {
+					match rel_type.as_str() {
+						| Some("m.replace") => {
+							// Only consider valid replacements
+							if Self::is_valid_replacement_event(&original_event, pdu).await? {
+								replace_events.push(relation);
+							}
+						},
+						| Some("m.reference") => {
+							reference_events.push(relation);
+						},
+						| _ => {
+							// Ignore other relation types for now
+							// Threads are in the database but not handled here
+							// Other types are not specified AFAICT.
+						},
+					}
+				}
+			}
+		}
+
+		// If no relations to bundle, return None
+		if replace_events.is_empty() && reference_events.is_empty() {
+			return Ok(None);
+		}
+
+		let mut bundled = BundledMessageLikeRelations::new();
+
+		// Handle m.replace relations - find the most recent one
+		if !replace_events.is_empty() {
+			let most_recent_replacement = Self::find_most_recent_replacement(&replace_events)?;
+
+			// Convert the replacement event to the bundled format
+			if let Some(replacement_pdu) = most_recent_replacement {
+				// According to the Matrix spec, we should include the full event as raw JSON
+				let replacement_json = serde_json::to_string(replacement_pdu)
+					.map_err(|e| err!(Database("Failed to serialize replacement event: {e}")))?;
+				let raw_value = serde_json::value::RawValue::from_string(replacement_json)
+					.map_err(|e| err!(Database("Failed to create RawValue: {e}")))?;
+				bundled.replace = Some(Box::new(raw_value));
+			}
+		}
+
+		// Handle m.reference relations - collect event IDs
+		if !reference_events.is_empty() {
+			let reference_chunk = Self::build_reference_chunk(&reference_events)?;
+			if !reference_chunk.is_empty() {
+				bundled.reference = Some(Box::new(ReferenceChunk::new(reference_chunk)));
+			}
+		}
+
+		// TODO: Handle other relation types (m.annotation, etc.) when specified
+
+		Ok(Some(bundled))
+	}
+
+	/// Build reference chunk for m.reference bundled aggregations
+	fn build_reference_chunk(
+		reference_events: &[&PdusIterItem],
+	) -> Result<Vec<BundledReference>> {
+		let mut chunk = Vec::with_capacity(reference_events.len());
+
+		for relation in reference_events {
+			let pdu = &relation.1;
+
+			let reference_entry = BundledReference::new(pdu.event_id().to_owned());
+			chunk.push(reference_entry);
+		}
+
+		// Don't sort, order is unspecified
+
+		Ok(chunk)
+	}
+
+	/// Find the most recent replacement event based on origin_server_ts and
+	/// lexicographic event_id ordering
+	fn find_most_recent_replacement<'a>(
+		replacement_events: &'a [&'a PdusIterItem],
+	) -> Result<Option<&'a PduEvent>> {
+		if replacement_events.is_empty() {
+			return Ok(None);
+		}
+
+		let mut most_recent: Option<&PduEvent> = None;
+
+		// Jank, is there a better way to do this?
+		for relation in replacement_events {
+			let pdu = &relation.1;
+
+			match most_recent {
+				| None => {
+					most_recent = Some(pdu);
+				},
+				| Some(current_most_recent) => {
+					// Compare by origin_server_ts first
+					match pdu
+						.origin_server_ts()
+						.cmp(&current_most_recent.origin_server_ts())
+					{
+						| std::cmp::Ordering::Greater => {
+							most_recent = Some(pdu);
+						},
+						| std::cmp::Ordering::Equal => {
+							// If timestamps are equal, use lexicographic ordering of event_id
+							if pdu.event_id() > current_most_recent.event_id() {
+								most_recent = Some(pdu);
+							}
+						},
+						| std::cmp::Ordering::Less => {
+							// Keep current most recent
+						},
+					}
+				},
+			}
+		}
+
+		Ok(most_recent)
+	}
+
+	/// Adds bundled aggregations to a PDU's unsigned field
+	#[tracing::instrument(skip(self, pdu), level = "debug")]
+	pub async fn add_bundled_aggregations_to_pdu(
+		&self,
+		user_id: &UserId,
+		pdu: &mut PduEvent,
+	) -> Result<()> {
+		if pdu.is_redacted() {
+			return Ok(());
+		}
+
+		let bundled_aggregations = self
+			.get_bundled_aggregations(user_id, pdu.room_id(), pdu.event_id())
+			.await?;
+
+		if let Some(aggregations) = bundled_aggregations {
+			let aggregations_json = serde_json::to_value(aggregations)
+				.map_err(|e| err!(Database("Failed to serialize bundled aggregations: {e}")))?;
+
+			Self::add_bundled_aggregations_to_unsigned(pdu, aggregations_json)?;
+		}
+
+		Ok(())
+	}
+
+	/// Helper method to add bundled aggregations to a PDU's unsigned
+	/// field
+	fn add_bundled_aggregations_to_unsigned(
+		pdu: &mut PduEvent,
+		aggregations_json: serde_json::Value,
+	) -> Result<()> {
+		use serde_json::{
+			Map, Value as JsonValue,
+			value::{RawValue as RawJsonValue, to_raw_value},
+		};
+
+		let mut unsigned: Map<String, JsonValue> = pdu
+			.unsigned
+			.as_deref()
+			.map(RawJsonValue::get)
+			.map_or_else(|| Ok(Map::new()), serde_json::from_str)
+			.map_err(|e| err!(Database("Invalid unsigned in pdu event: {e}")))?;
+
+		let relations = unsigned
+			.entry("m.relations")
+			.or_insert_with(|| JsonValue::Object(Map::new()))
+			.as_object_mut()
+			.ok_or_else(|| err!(Database("m.relations is not an object")))?;
+
+		if let JsonValue::Object(aggregations_map) = aggregations_json {
+			for (rel_type, aggregation) in aggregations_map {
+				relations.insert(rel_type, aggregation);
+			}
+		}
+
+		pdu.unsigned = Some(to_raw_value(&unsigned)?);
+
+		Ok(())
+	}
+
+	/// Validates that an event is acceptable as a replacement for another event
+	/// See C/S spec "Validity of replacement events"
+	#[tracing::instrument(level = "debug")]
+	async fn is_valid_replacement_event(
+		original_event: &PduEvent,
+		replacement_event: &PduEvent,
+	) -> Result<bool> {
+		// 1. Same room_id
+		if original_event.room_id() != replacement_event.room_id() {
+			return Ok(false);
+		}
+
+		// 2. Same sender
+		if original_event.sender() != replacement_event.sender() {
+			return Ok(false);
+		}
+
+		// 3. Same type
+		if original_event.event_type() != replacement_event.event_type() {
+			return Ok(false);
+		}
+
+		// 4. Neither event should have a state_key property
+		if original_event.state_key().is_some() || replacement_event.state_key().is_some() {
+			return Ok(false);
+		}
+
+		// 5. Original event must not have rel_type of m.replace
+		let original_content = original_event.get_content_as_value();
+		if let Some(relates_to) = original_content.get("m.relates_to") {
+			if let Some(rel_type) = relates_to.get("rel_type") {
+				if rel_type.as_str() == Some("m.replace") {
+					return Ok(false);
+				}
+			}
+		}
+
+		// 6. Replacement event must have m.new_content property
+		// Skip this check for encrypted events, as m.new_content would be inside the
+		// encrypted payload
+		if replacement_event.event_type() != &ruma::events::TimelineEventType::RoomEncrypted {
+			let replacement_content = replacement_event.get_content_as_value();
+			if replacement_content.get("m.new_content").is_none() {
+				return Ok(false);
+			}
+		}
+
+		Ok(true)
+	}
+}
+
+#[cfg(test)]
+mod tests {
+	use conduwuit_core::pdu::{EventHash, PduEvent};
+	use ruma::{UInt, events::TimelineEventType, owned_event_id, owned_room_id, owned_user_id};
+	use serde_json::{Value as JsonValue, json, value::to_raw_value};
+
+	fn create_test_pdu(unsigned_content: Option<JsonValue>) -> PduEvent {
+		PduEvent {
+			event_id: owned_event_id!("$test:example.com"),
+			room_id: owned_room_id!("!test:example.com"),
+			sender: owned_user_id!("@test:example.com"),
+			origin_server_ts: UInt::try_from(1_234_567_890_u64).unwrap(),
+			kind: TimelineEventType::RoomMessage,
+			content: to_raw_value(&json!({"msgtype": "m.text", "body": "test"})).unwrap(),
+			state_key: None,
+			prev_events: vec![],
+			depth: UInt::from(1_u32),
+			auth_events: vec![],
+			redacts: None,
+			unsigned: unsigned_content.map(|content| to_raw_value(&content).unwrap()),
+			hashes: EventHash { sha256: "test_hash".to_owned() },
+			signatures: None,
+			origin: None,
+		}
+	}
+
+	fn create_bundled_aggregations() -> JsonValue {
+		json!({
+			"m.replace": {
+				"event_id": "$replace:example.com",
+				"origin_server_ts": 1_234_567_890,
+				"sender": "@replacer:example.com"
+			},
+			"m.reference": {
+				"count": 5,
+				"chunk": [
+					"$ref1:example.com",
+					"$ref2:example.com"
+				]
+			}
+		})
+	}
+
+	#[test]
+	fn test_add_bundled_aggregations_to_unsigned_no_existing_unsigned() {
+		let mut pdu = create_test_pdu(None);
+		let aggregations = create_bundled_aggregations();
+
+		let result = super::super::Service::add_bundled_aggregations_to_unsigned(
+			&mut pdu,
+			aggregations.clone(),
+		);
+		assert!(result.is_ok(), "Should succeed when no unsigned field exists");
+
+		assert!(pdu.unsigned.is_some(), "Unsigned field should be created");
+
+		let unsigned_str = pdu.unsigned.as_ref().unwrap().get();
+		let unsigned: JsonValue = serde_json::from_str(unsigned_str).unwrap();
+
+		assert!(unsigned.get("m.relations").is_some(), "m.relations should exist");
+		assert_eq!(
+			unsigned["m.relations"], aggregations,
+			"Relations should match the aggregations"
+		);
+	}
+
+	#[test]
+	fn test_add_bundled_aggregations_to_unsigned_overwrite_same_relation_type() {
+		let existing_unsigned = json!({
+			"m.relations": {
+				"m.replace": {
+					"event_id": "$old_replace:example.com",
+					"origin_server_ts": 1_111_111_111,
+					"sender": "@old_replacer:example.com"
+				}
+			}
+		});
+
+		let mut pdu = create_test_pdu(Some(existing_unsigned));
+		let new_aggregations = create_bundled_aggregations();
+
+		let result = super::super::Service::add_bundled_aggregations_to_unsigned(
+			&mut pdu,
+			new_aggregations.clone(),
+		);
+		assert!(result.is_ok(), "Should succeed when overwriting same relation type");
+
+		let unsigned_str = pdu.unsigned.as_ref().unwrap().get();
+		let unsigned: JsonValue = serde_json::from_str(unsigned_str).unwrap();
+
+		let relations = &unsigned["m.relations"];
+
+		assert_eq!(
+			relations["m.replace"], new_aggregations["m.replace"],
+			"m.replace should be updated"
+		);
+		assert_eq!(
+			relations["m.replace"]["event_id"], "$replace:example.com",
+			"Should have new event_id"
+		);
+
+		assert!(relations.get("m.reference").is_some(), "New m.reference should be added");
+	}
+
+	#[test]
+	fn test_add_bundled_aggregations_to_unsigned_preserve_other_unsigned_fields() {
+		// Test case: Other unsigned fields should be preserved
+		let existing_unsigned = json!({
+			"age": 98765,
+			"prev_content": {"msgtype": "m.text", "body": "old message"},
+			"redacted_because": {"event_id": "$redaction:example.com"},
+			"m.relations": {
+				"m.annotation": {"count": 1}
+			}
+		});
+
+		let mut pdu = create_test_pdu(Some(existing_unsigned));
+		let new_aggregations = json!({
+			"m.replace": {"event_id": "$new:example.com"}
+		});
+
+		let result = super::super::Service::add_bundled_aggregations_to_unsigned(
+			&mut pdu,
+			new_aggregations,
+		);
+		assert!(result.is_ok(), "Should succeed while preserving other fields");
+
+		let unsigned_str = pdu.unsigned.as_ref().unwrap().get();
+		let unsigned: JsonValue = serde_json::from_str(unsigned_str).unwrap();
+
+		// Verify all existing fields are preserved
+		assert_eq!(unsigned["age"], 98765, "age should be preserved");
+		assert!(unsigned.get("prev_content").is_some(), "prev_content should be preserved");
+		assert!(
+			unsigned.get("redacted_because").is_some(),
+			"redacted_because should be preserved"
+		);
+
+		// Verify relations were merged correctly
+		let relations = &unsigned["m.relations"];
+		assert!(
+			relations.get("m.annotation").is_some(),
+			"Existing m.annotation should be preserved"
+		);
+		assert!(relations.get("m.replace").is_some(), "New m.replace should be added");
+	}
+
+	#[test]
+	fn test_add_bundled_aggregations_to_unsigned_invalid_existing_unsigned() {
+		// Test case: Invalid JSON in existing unsigned should result in error
+		let mut pdu = create_test_pdu(None);
+		// Manually set invalid unsigned data
+		pdu.unsigned = Some(to_raw_value(&"invalid json").unwrap());
+
+		let aggregations = create_bundled_aggregations();
+		let result =
+			super::super::Service::add_bundled_aggregations_to_unsigned(&mut pdu, aggregations);
+
+		assert!(result.is_err(), "fails when existing unsigned is invalid");
+		// Should we ignore the error and overwrite anyway?
+	}
+
+	// Test helper function to create test PDU events
+	fn create_test_event(
+		event_id: &str,
+		room_id: &str,
+		sender: &str,
+		event_type: TimelineEventType,
+		content: &JsonValue,
+		state_key: Option<&str>,
+	) -> PduEvent {
+		PduEvent {
+			event_id: event_id.try_into().unwrap(),
+			room_id: room_id.try_into().unwrap(),
+			sender: sender.try_into().unwrap(),
+			origin_server_ts: UInt::try_from(1_234_567_890_u64).unwrap(),
+			kind: event_type,
+			content: to_raw_value(&content).unwrap(),
+			state_key: state_key.map(Into::into),
+			prev_events: vec![],
+			depth: UInt::from(1_u32),
+			auth_events: vec![],
+			redacts: None,
+			unsigned: None,
+			hashes: EventHash { sha256: "test_hash".to_owned() },
+			signatures: None,
+			origin: None,
+		}
+	}
+
+	/// Test that a valid replacement event passes validation
+	#[tokio::test]
+	async fn test_valid_replacement_event() {
+		let original = create_test_event(
+			"$original:example.com",
+			"!room:example.com",
+			"@user:example.com",
+			TimelineEventType::RoomMessage,
+			&json!({"msgtype": "m.text", "body": "original message"}),
+			None,
+		);
+
+		let replacement = create_test_event(
+			"$replacement:example.com",
+			"!room:example.com",
+			"@user:example.com",
+			TimelineEventType::RoomMessage,
+			&json!({
+				"msgtype": "m.text",
+				"body": "* edited message",
+				"m.new_content": {
+					"msgtype": "m.text",
+					"body": "edited message"
+				},
+				"m.relates_to": {
+					"rel_type": "m.replace",
+					"event_id": "$original:example.com"
+				}
+			}),
+			None,
+		);
+
+		let result =
+			super::super::Service::is_valid_replacement_event(&original, &replacement).await;
+		assert!(result.is_ok(), "Validation should succeed");
+		assert!(result.unwrap(), "Valid replacement event should be accepted");
+	}
+
+	/// Test replacement event with different room ID is rejected
+	#[tokio::test]
+	async fn test_replacement_event_different_room() {
+		let original = create_test_event(
+			"$original:example.com",
+			"!room1:example.com",
+			"@user:example.com",
+			TimelineEventType::RoomMessage,
+			&json!({"msgtype": "m.text", "body": "original message"}),
+			None,
+		);
+
+		let replacement = create_test_event(
+			"$replacement:example.com",
+			"!room2:example.com", // Different room
+			"@user:example.com",
+			TimelineEventType::RoomMessage,
+			&json!({
+				"msgtype": "m.text",
+				"body": "* edited message",
+				"m.new_content": {
+					"msgtype": "m.text",
+					"body": "edited message"
+				}
+			}),
+			None,
+		);
+
+		let result =
+			super::super::Service::is_valid_replacement_event(&original, &replacement).await;
+		assert!(result.is_ok(), "Validation should succeed");
+		assert!(!result.unwrap(), "Different room ID should be rejected");
+	}
+
+	/// Test replacement event with different sender is rejected
+	#[tokio::test]
+	async fn test_replacement_event_different_sender() {
+		let original = create_test_event(
+			"$original:example.com",
+			"!room:example.com",
+			"@user1:example.com",
+			TimelineEventType::RoomMessage,
+			&json!({"msgtype": "m.text", "body": "original message"}),
+			None,
+		);
+
+		let replacement = create_test_event(
+			"$replacement:example.com",
+			"!room:example.com",
+			"@user2:example.com", // Different sender
+			TimelineEventType::RoomMessage,
+			&json!({
+				"msgtype": "m.text",
+				"body": "* edited message",
+				"m.new_content": {
+					"msgtype": "m.text",
+					"body": "edited message"
+				}
+			}),
+			None,
+		);
+
+		let result =
+			super::super::Service::is_valid_replacement_event(&original, &replacement).await;
+		assert!(result.is_ok(), "Validation should succeed");
+		assert!(!result.unwrap(), "Different sender should be rejected");
+	}
+
+	/// Test replacement event with different type is rejected
+	#[tokio::test]
+	async fn test_replacement_event_different_type() {
+		let original = create_test_event(
+			"$original:example.com",
+			"!room:example.com",
+			"@user:example.com",
+			TimelineEventType::RoomMessage,
+			&json!({"msgtype": "m.text", "body": "original message"}),
+			None,
+		);
+
+		let replacement = create_test_event(
+			"$replacement:example.com",
+			"!room:example.com",
+			"@user:example.com",
+			TimelineEventType::RoomTopic, // Different event type
+			&json!({
+				"topic": "new topic",
+				"m.new_content": {
+					"topic": "new topic"
+				}
+			}),
+			None,
+		);
+
+		let result =
+			super::super::Service::is_valid_replacement_event(&original, &replacement).await;
+		assert!(result.is_ok(), "Validation should succeed");
+		assert!(!result.unwrap(), "Different event type should be rejected");
+	}
+
+	/// Test replacement event with state key is rejected
+	#[tokio::test]
+	async fn test_replacement_event_with_state_key() {
+		let original = create_test_event(
+			"$original:example.com",
+			"!room:example.com",
+			"@user:example.com",
+			TimelineEventType::RoomName,
+			&json!({"name": "room name"}),
+			Some(""), // Has state key
+		);
+
+		let replacement = create_test_event(
+			"$replacement:example.com",
+			"!room:example.com",
+			"@user:example.com",
+			TimelineEventType::RoomName,
+			&json!({
+				"name": "new room name",
+				"m.new_content": {
+					"name": "new room name"
+				}
+			}),
+			None,
+		);
+
+		let result =
+			super::super::Service::is_valid_replacement_event(&original, &replacement).await;
+		assert!(result.is_ok(), "Validation should succeed");
+		assert!(!result.unwrap(), "Event with state key should be rejected");
+	}
+
+	/// Test replacement of an event that is already a replacement is rejected
+	#[tokio::test]
+	async fn test_replacement_event_original_is_replacement() {
+		let original = create_test_event(
+			"$original:example.com",
+			"!room:example.com",
+			"@user:example.com",
+			TimelineEventType::RoomMessage,
+			&json!({
+				"msgtype": "m.text",
+				"body": "* edited message",
+				"m.relates_to": {
+					"rel_type": "m.replace", // Original is already a replacement
+					"event_id": "$some_other:example.com"
+				}
+			}),
+			None,
+		);
+
+		let replacement = create_test_event(
+			"$replacement:example.com",
+			"!room:example.com",
+			"@user:example.com",
+			TimelineEventType::RoomMessage,
+			&json!({
+				"msgtype": "m.text",
+				"body": "* edited again",
+				"m.new_content": {
+					"msgtype": "m.text",
+					"body": "edited again"
+				}
+			}),
+			None,
+		);
+
+		let result =
+			super::super::Service::is_valid_replacement_event(&original, &replacement).await;
+		assert!(result.is_ok(), "Validation should succeed");
+		assert!(!result.unwrap(), "Replacement of replacement should be rejected");
+	}
+
+	/// Test replacement event missing m.new_content is rejected
+	#[tokio::test]
+	async fn test_replacement_event_missing_new_content() {
+		let original = create_test_event(
+			"$original:example.com",
+			"!room:example.com",
+			"@user:example.com",
+			TimelineEventType::RoomMessage,
+			&json!({"msgtype": "m.text", "body": "original message"}),
+			None,
+		);
+
+		let replacement = create_test_event(
+			"$replacement:example.com",
+			"!room:example.com",
+			"@user:example.com",
+			TimelineEventType::RoomMessage,
+			&json!({
+				"msgtype": "m.text",
+				"body": "* edited message"
+				// Missing m.new_content
+			}),
+			None,
+		);
+
+		let result =
+			super::super::Service::is_valid_replacement_event(&original, &replacement).await;
+		assert!(result.is_ok(), "Validation should succeed");
+		assert!(!result.unwrap(), "Missing m.new_content should be rejected");
+	}
+
+	/// Test encrypted replacement event without m.new_content is accepted
+	#[tokio::test]
+	async fn test_replacement_event_encrypted_missing_new_content_is_valid() {
+		let original = create_test_event(
+			"$original:example.com",
+			"!room:example.com",
+			"@user:example.com",
+			TimelineEventType::RoomEncrypted,
+			&json!({
+				"algorithm": "m.megolm.v1.aes-sha2",
+				"ciphertext": "encrypted_payload_base64",
+				"sender_key": "sender_key",
+				"session_id": "session_id"
+			}),
+			None,
+		);
+
+		let replacement = create_test_event(
+			"$replacement:example.com",
+			"!room:example.com",
+			"@user:example.com",
+			TimelineEventType::RoomEncrypted,
+			&json!({
+				"algorithm": "m.megolm.v1.aes-sha2",
+				"ciphertext": "encrypted_replacement_payload_base64",
+				"sender_key": "sender_key",
+				"session_id": "session_id",
+				"m.relates_to": {
+					"rel_type": "m.replace",
+					"event_id": "$original:example.com"
+				}
+				// No m.new_content in cleartext - this is valid for encrypted events
+			}),
+			None,
+		);
+
+		let result =
+			super::super::Service::is_valid_replacement_event(&original, &replacement).await;
+		assert!(result.is_ok(), "Validation should succeed");
+		assert!(
+			result.unwrap(),
+			"Encrypted replacement without cleartext m.new_content should be accepted"
+		);
+	}
+}

src/service/rooms/pdu_metadata/data.rs

@@ -3,7 +3,6 @@ use std::{mem::size_of, sync::Arc};
 use conduwuit::{
 	PduCount, PduEvent,
 	arrayvec::ArrayVec,
-	result::LogErr,
 	utils::{
 		ReadyExt,
 		stream::{TryIgnore, WidebandExt},
@@ -80,9 +79,7 @@ impl Data {
 
 			let mut pdu = self.services.timeline.get_pdu_from_id(&pdu_id).await.ok()?;
 
-			if pdu.sender != user_id {
-				pdu.remove_transaction_id().log_err().ok();
-			}
+			pdu.set_unsigned(Some(user_id));
 
 			Some((shorteventid, pdu))
 		})

src/service/rooms/pdu_metadata/mod.rs

@@ -1,3 +1,4 @@
+mod bundled_aggregations;
 mod data;
 use std::sync::Arc;
 

src/service/rooms/search/mod.rs

@@ -127,7 +127,12 @@ pub async fn search_pdus<'a>(
 				.then_some(pdu)
 		})
 		.skip(query.skip)
-		.take(query.limit);
+		.take(query.limit)
+		.map(move |mut pdu| {
+			pdu.set_unsigned(query.user_id);
+			// TODO: bundled aggregation
+			pdu
+		});
 
 	Ok((count, pdus))
 }

src/service/rooms/threads/mod.rs

@@ -160,9 +160,7 @@ impl Service {
 				let mut pdu = self.services.timeline.get_pdu_from_id(&pdu_id).await.ok()?;
 				let pdu_id: PduId = pdu_id.into();
 
-				if pdu.sender != user_id {
-					pdu.remove_transaction_id().ok();
-				}
+				pdu.set_unsigned(Some(user_id));
 
 				Some((pdu_id.shorteventid, pdu))
 			});

src/service/rooms/timeline/data.rs

@@ -1,14 +1,11 @@
-use std::{borrow::Borrow, sync::Arc};
+use std::sync::Arc;
 
 use conduwuit::{
-	Err, PduCount, PduEvent, Result, at, err,
-	result::{LogErr, NotFound},
-	utils,
-	utils::stream::TryReadyExt,
+	Err, PduCount, PduEvent, Result, at, err, result::NotFound, utils, utils::stream::TryReadyExt,
 };
 use database::{Database, Deserialized, Json, KeyVal, Map};
 use futures::{FutureExt, Stream, TryFutureExt, TryStreamExt, future::select_ok, pin_mut};
-use ruma::{CanonicalJsonObject, EventId, OwnedUserId, RoomId, UserId, api::Direction};
+use ruma::{CanonicalJsonObject, EventId, OwnedUserId, RoomId, api::Direction};
 
 use super::{PduId, RawPduId};
 use crate::{Dep, rooms, rooms::short::ShortRoomId};
@@ -46,12 +43,8 @@ impl Data {
 	}
 
 	#[inline]
-	pub(super) async fn last_timeline_count(
-		&self,
-		sender_user: Option<&UserId>,
-		room_id: &RoomId,
-	) -> Result<PduCount> {
-		let pdus_rev = self.pdus_rev(sender_user, room_id, PduCount::max());
+	pub(super) async fn last_timeline_count(&self, room_id: &RoomId) -> Result<PduCount> {
+		let pdus_rev = self.pdus_rev(room_id, PduCount::max());
 
 		pin_mut!(pdus_rev);
 		let last_count = pdus_rev
@@ -65,12 +58,8 @@ impl Data {
 	}
 
 	#[inline]
-	pub(super) async fn latest_pdu_in_room(
-		&self,
-		sender_user: Option<&UserId>,
-		room_id: &RoomId,
-	) -> Result<PduEvent> {
-		let pdus_rev = self.pdus_rev(sender_user, room_id, PduCount::max());
+	pub(super) async fn latest_pdu_in_room(&self, room_id: &RoomId) -> Result<PduEvent> {
+		let pdus_rev = self.pdus_rev(room_id, PduCount::max());
 
 		pin_mut!(pdus_rev);
 		pdus_rev
@@ -223,7 +212,6 @@ impl Data {
 	/// order.
 	pub(super) fn pdus_rev<'a>(
 		&'a self,
-		user_id: Option<&'a UserId>,
 		room_id: &'a RoomId,
 		until: PduCount,
 	) -> impl Stream<Item = Result<PdusIterItem>> + Send + 'a {
@@ -233,14 +221,13 @@ impl Data {
 				self.pduid_pdu
 					.rev_raw_stream_from(&current)
 					.ready_try_take_while(move |(key, _)| Ok(key.starts_with(&prefix)))
-					.ready_and_then(move |item| Self::each_pdu(item, user_id))
+					.ready_and_then(Self::from_json_slice)
 			})
 			.try_flatten_stream()
 	}
 
 	pub(super) fn pdus<'a>(
 		&'a self,
-		user_id: Option<&'a UserId>,
 		room_id: &'a RoomId,
 		from: PduCount,
 	) -> impl Stream<Item = Result<PdusIterItem>> + Send + 'a {
@@ -250,21 +237,15 @@ impl Data {
 				self.pduid_pdu
 					.raw_stream_from(&current)
 					.ready_try_take_while(move |(key, _)| Ok(key.starts_with(&prefix)))
-					.ready_and_then(move |item| Self::each_pdu(item, user_id))
+					.ready_and_then(Self::from_json_slice)
 			})
 			.try_flatten_stream()
 	}
 
-	fn each_pdu((pdu_id, pdu): KeyVal<'_>, user_id: Option<&UserId>) -> Result<PdusIterItem> {
+	fn from_json_slice((pdu_id, pdu): KeyVal<'_>) -> Result<PdusIterItem> {
 		let pdu_id: RawPduId = pdu_id.into();
 
-		let mut pdu = serde_json::from_slice::<PduEvent>(pdu)?;
-
-		if Some(pdu.sender.borrow()) != user_id {
-			pdu.remove_transaction_id().log_err().ok();
-		}
-
-		pdu.add_age().log_err().ok();
+		let pdu = serde_json::from_slice::<PduEvent>(pdu)?;
 
 		Ok((pdu_id.pdu_count(), pdu))
 	}

src/service/rooms/timeline/mod.rs

@@ -165,7 +165,7 @@ impl Service {
 
 	#[tracing::instrument(skip(self), level = "debug")]
 	pub async fn first_item_in_room(&self, room_id: &RoomId) -> Result<(PduCount, PduEvent)> {
-		let pdus = self.pdus(None, room_id, None);
+		let pdus = self.pdus(room_id, None);
 
 		pin_mut!(pdus);
 		pdus.try_next()
@@ -175,16 +175,12 @@ impl Service {
 
 	#[tracing::instrument(skip(self), level = "debug")]
 	pub async fn latest_pdu_in_room(&self, room_id: &RoomId) -> Result<PduEvent> {
-		self.db.latest_pdu_in_room(None, room_id).await
+		self.db.latest_pdu_in_room(room_id).await
 	}
 
 	#[tracing::instrument(skip(self), level = "debug")]
-	pub async fn last_timeline_count(
-		&self,
-		sender_user: Option<&UserId>,
-		room_id: &RoomId,
-	) -> Result<PduCount> {
-		self.db.last_timeline_count(sender_user, room_id).await
+	pub async fn last_timeline_count(&self, room_id: &RoomId) -> Result<PduCount> {
+		self.db.last_timeline_count(room_id).await
 	}
 
 	/// Returns the `count` of this pdu's id.
@@ -545,6 +541,10 @@ impl Service {
 			| _ => {},
 		}
 
+		// CONCERN: If we receive events with a relation out-of-order, we never write
+		// their relation / thread. We need some kind of way to trigger when we receive
+		// this event, and potentially a way to rebuild the table entirely.
+
 		if let Ok(content) = pdu.get_content::<ExtractRelatesToEventId>() {
 			if let Ok(related_pducount) = self.get_pdu_count(&content.relates_to.event_id).await {
 				self.services
@@ -996,34 +996,30 @@ impl Service {
 	#[inline]
 	pub fn all_pdus<'a>(
 		&'a self,
-		user_id: &'a UserId,
 		room_id: &'a RoomId,
 	) -> impl Stream<Item = PdusIterItem> + Send + 'a {
-		self.pdus(Some(user_id), room_id, None).ignore_err()
+		self.pdus(room_id, None).ignore_err()
 	}
 
 	/// Reverse iteration starting at from.
 	#[tracing::instrument(skip(self), level = "debug")]
 	pub fn pdus_rev<'a>(
 		&'a self,
-		user_id: Option<&'a UserId>,
 		room_id: &'a RoomId,
 		until: Option<PduCount>,
 	) -> impl Stream<Item = Result<PdusIterItem>> + Send + 'a {
 		self.db
-			.pdus_rev(user_id, room_id, until.unwrap_or_else(PduCount::max))
+			.pdus_rev(room_id, until.unwrap_or_else(PduCount::max))
 	}
 
 	/// Forward iteration starting at from.
 	#[tracing::instrument(skip(self), level = "debug")]
 	pub fn pdus<'a>(
 		&'a self,
-		user_id: Option<&'a UserId>,
 		room_id: &'a RoomId,
 		from: Option<PduCount>,
 	) -> impl Stream<Item = Result<PdusIterItem>> + Send + 'a {
-		self.db
-			.pdus(user_id, room_id, from.unwrap_or_else(PduCount::min))
+		self.db.pdus(room_id, from.unwrap_or_else(PduCount::min))
 	}
 
 	/// Replace a PDU with the redacted form.

src/service/sending/sender.rs

@@ -781,7 +781,7 @@ impl Service {
 
 		for pdu in pdus {
 			// Redacted events are not notification targets (we don't send push for them)
-			if pdu.contains_unsigned_property("redacted_because", serde_json::Value::is_string) {
+			if pdu.is_redacted() {
 				continue;
 			}