파일을 다운로드할 때 전체 파일을 메모리에 올리는 대신 서비스 워커에서 스트리밍으로 복호화하도록 변경

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/lib/client/transfer/chunkedUpload.ts

@@ -4,6 +4,7 @@ import pLimit from "p-limit";
 import { encodeToBase64, encryptChunk } from "#lib/shared/crypto/index.js";
 import { CHUNK_SIZE, getChunkCount, getEncryptedSize } from "#lib/shared/format/index.js";
 import { BoundedQueue } from "#lib/utils/concurrency/index.js";
+import { createSpeedMeter } from "#lib/utils/speedMeter.js";
 
 interface UploadStats {
   progress: number;
@@ -15,59 +16,6 @@ interface EncryptedChunk {
   data: ArrayBuffer;
 }
 
-const createSpeedMeter = (timeWindow = 3000, minInterval = 200, warmupPeriod = 500) => {
-  const samples: { t: number; b: number }[] = [];
-  let lastSpeed = 0;
-  let startTime: number | null = null;
-
-  return (bytesNow?: number) => {
-    if (bytesNow === undefined) return lastSpeed;
-
-    const now = performance.now();
-
-    // Initialize start time on first call
-    if (startTime === null) {
-      startTime = now;
-    }
-
-    // Check if enough time has passed since the last sample
-    const lastSample = samples[samples.length - 1];
-    if (lastSample && now - lastSample.t < minInterval) {
-      return lastSpeed;
-    }
-
-    samples.push({ t: now, b: bytesNow });
-
-    // Remove old samples outside the time window
-    const cutoff = now - timeWindow;
-    while (samples.length > 2 && samples[0]!.t < cutoff) samples.shift();
-
-    // Need at least 2 samples to calculate speed
-    if (samples.length < 2) {
-      return lastSpeed;
-    }
-
-    const first = samples[0]!;
-    const dt = now - first.t;
-    const db = bytesNow - first.b;
-
-    if (dt >= minInterval) {
-      const instantSpeed = (db / dt) * 1000;
-      // Apply EMA for smoother speed transitions
-      const alpha = 0.3;
-      const rawSpeed =
-        lastSpeed === 0 ? instantSpeed : alpha * instantSpeed + (1 - alpha) * lastSpeed;
-
-      // Apply warmup ramp to prevent initial overestimation
-      const elapsed = now - startTime;
-      const warmupWeight = Math.min(1, elapsed / warmupPeriod);
-      lastSpeed = rawSpeed * warmupWeight;
-    }
-
-    return lastSpeed;
-  };
-};
-
 const encryptChunkData = async (chunk: Blob, dataKey: CryptoKey): Promise<ArrayBuffer> => {
   return await encryptChunk(await chunk.arrayBuffer(), dataKey);
 };