fix: FTTが有効かつsinceIdのみを指定した場合に帰って来るレスポンスが逆順である問題

packages/backend/src/core/FanoutTimelineEndpointService.ts

@@ -61,8 +61,8 @@ export class FanoutTimelineEndpointService {
 		// 呼び出し元と以下の処理をシンプルにするためにdbFallbackを置き換える
 		if (!ps.useDbFallback) ps.dbFallback = () => Promise.resolve([]);
 
-		const shouldPrepend = ps.sinceId && !ps.untilId;
-		const idCompare: (a: string, b: string) => number = shouldPrepend ? (a, b) => a < b ? -1 : 1 : (a, b) => a > b ? -1 : 1;
+		const ascending = ps.sinceId && !ps.untilId;
+		const idCompare: (a: string, b: string) => number = ascending ? (a, b) => a < b ? -1 : 1 : (a, b) => a > b ? -1 : 1;
 
 		const redisResult = await this.fanoutTimelineService.getMulti(ps.redisTimelines, ps.untilId, ps.sinceId);
 
@@ -142,26 +142,23 @@ export class FanoutTimelineEndpointService {
 
 				if (ps.allowPartial ? redisTimeline.length !== 0 : redisTimeline.length >= ps.limit) {
 					// 十分Redisからとれた
-					const result = redisTimeline.slice(0, ps.limit);
-					if (shouldPrepend) result.reverse();
-					return result;
+					return redisTimeline.slice(0, ps.limit);
 				}
 			}
 
 			// まだ足りない分はDBにフォールバック
 			const remainingToRead = ps.limit - redisTimeline.length;
 			let dbUntil: string | null;
 			let dbSince: string | null;
-			if (shouldPrepend) {
-				redisTimeline.reverse();
+			if (ascending) {
 				dbUntil = ps.untilId;
 				dbSince = noteIds[noteIds.length - 1];
 			} else {
 				dbUntil = noteIds[noteIds.length - 1];
 				dbSince = ps.sinceId;
 			}
 			const gotFromDb = await ps.dbFallback(dbUntil, dbSince, remainingToRead);
-			return shouldPrepend ? [...gotFromDb, ...redisTimeline] : [...redisTimeline, ...gotFromDb];
+			return [...redisTimeline, ...gotFromDb];
 		}
 
 		return await ps.dbFallback(ps.untilId, ps.sinceId, ps.limit);