Dedupe sharded manifest/rounds rows on overlap

Re-rendered batches occasionally produce a second shard whose rows
collide on (match_id, map_name[, round]) — Svelte's each_key_duplicate
fired on the homepage grid. Keep the freshest uploaded_at per key.

src/lib/api/hf.ts

@@ -27,7 +27,9 @@ async function listIndexShards(
 		});
 }
 
-async function loadShardedIndex<T>(
+type IndexRow = { match_id: number; map_name: string; uploaded_at: string; round?: number };
+
+async function loadShardedIndex<T extends IndexRow>(
 	prefix: 'manifest' | 'rounds',
 	opts: FetchOptions
 ): Promise<T[]> {
@@ -36,7 +38,19 @@ async function loadShardedIndex<T>(
 	const shards = await Promise.all(
 		paths.map((p) => fetchParquetRows<T>(resolveUrl(p), opts))
 	);
-	return shards.flat();
+	// A re-rendered batch produces a second shard whose rows collide with the
+	// original on (match,map[,round]). Keep the freshest copy per key.
+	const keyOf =
+		prefix === 'manifest'
+			? (r: T) => `${r.match_id}|${r.map_name}`
+			: (r: T) => `${r.match_id}|${r.map_name}|${r.round}`;
+	const latest = new Map<string, T>();
+	for (const r of shards.flat()) {
+		const k = keyOf(r);
+		const cur = latest.get(k);
+		if (!cur || r.uploaded_at > cur.uploaded_at) latest.set(k, r);
+	}
+	return Array.from(latest.values());
 }
 
 export function listMatches(opts: FetchOptions = {}): Promise<Match[]> {