default to main event for batch tokens

fix prev_batch token for legacy sync timeline

Signed-off-by: Jason Volk <jason@zemos.net>

src/api/client/context.rs

@@ -169,12 +169,14 @@ pub(crate) async fn get_context_route(
 		start: events_before
 			.last()
 			.map(at!(0))
+			.or(Some(base_token))
 			.as_ref()
 			.map(ToString::to_string),
 
 		end: events_after
 			.last()
 			.map(at!(0))
+			.or(Some(base_token))
 			.as_ref()
 			.map(ToString::to_string),
 

src/api/client/message.rs

@@ -136,8 +136,6 @@ pub(crate) async fn get_message_events_route(
 		.collect()
 		.await;
 
-	let start_token = events.first().map(at!(0)).unwrap_or(from);
-
 	let next_token = events.last().map(at!(0));
 
 	if !cfg!(feature = "element_hacks") {
@@ -156,7 +154,7 @@ pub(crate) async fn get_message_events_route(
 		.collect();
 
 	Ok(get_message_events::v3::Response {
-		start: start_token.to_string(),
+		start: from.to_string(),
 		end: next_token.as_ref().map(ToString::to_string),
 		chunk,
 		state,

src/api/client/sync/v3.rs

@@ -945,7 +945,6 @@ async fn load_joined_room(
 	let prev_batch = timeline_pdus
 		.first()
 		.map(at!(0))
-		.map(|count| count.saturating_sub(1))
 		.as_ref()
 		.map(ToString::to_string);