fix(app): refetch the tail when a channel window falls behind (#2565)

fluxer_app/src/features/messaging/state/MessagingMessages.ts

@@ -449,9 +449,9 @@ class Messages {
 	}
 
 	@action
-	handleLoadMessages(action: {channelId: string; jump?: JumpOptions}): boolean {
+	handleLoadMessages(action: {channelId: string; jump?: JumpOptions; tailProbe?: boolean}): boolean {
 		const messages = ChannelMessages.getOrCreate(action.channelId);
-		this.commitMessages(messages.beginLoad(action.jump));
+		this.commitMessages(action.tailProbe ? messages.beginProbeLoad() : messages.beginLoad(action.jump));
 		this.notifyChange();
 		return false;
 	}
@@ -505,6 +505,7 @@ class Messages {
 		hasMoreBefore?: boolean;
 		hasMoreAfter?: boolean;
 		cached?: boolean;
+		tailProbe?: boolean;
 		messages: Array<WireMessage>;
 	}): boolean {
 		const messages = ChannelMessages.getOrCreate(action.channelId).applyLoadedWindow({
@@ -515,6 +516,7 @@ class Messages {
 			hasMoreBefore: action.hasMoreBefore,
 			hasMoreAfter: action.hasMoreAfter,
 			cached: action.cached,
+			tailProbe: action.tailProbe,
 		});
 		this.commitMessages(messages);
 		this.notifyChange();
@@ -529,6 +531,15 @@ class Messages {
 		return false;
 	}
 
+	@action
+	handleTailProbeSettled(action: {channelId: string}): boolean {
+		const messages = ChannelMessages.get(action.channelId);
+		if (!messages?.probeLoading) return false;
+		this.commitMessages(messages.endProbeLoad());
+		this.notifyChange();
+		return true;
+	}
+
 	@action
 	handleLoadMessagesBlocked(action: {channelId: string}): boolean {
 		const messages = ChannelMessages.getOrCreate(action.channelId);