193 lines
9.0 KiB
JavaScript
193 lines
9.0 KiB
JavaScript
/* Exact, resumable asset synchronization shared by pages and workers. */
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(function (root) {
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'use strict';
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const CACHE = 'ytplayer-assets';
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const STATE = '/__ytp_asset_state';
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const url = (path, file) => path + '?v=' + file.h;
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function paths(manifest) {
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return Object.keys(manifest.files).sort();
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}
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function blocking(manifest, previous, activeLayout) {
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const names = new Set(Object.entries(manifest.groups)
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.filter(([name, group]) => name === 'core' || !group.background ||
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name === 'layout:' + activeLayout ||
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(previous?.groups[name] && previous.groups[name].contract !== group.contract))
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.map(([name]) => name));
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for (const name of names) for (const dependency of manifest.groups[name].dependencies || []) names.add(dependency);
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return [...new Set([...names].flatMap(name => manifest.groups[name].files))].sort();
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}
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function plan(manifest, keys) {
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const held = new Set(keys);
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return {
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missing: paths(manifest).map(path => url(path, manifest.files[path])).filter(key => !held.has(key)),
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blocking: blocking(manifest).map(path => url(path, manifest.files[path])),
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};
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}
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function retained(current, previous) {
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const currentPaths = new Set(paths(current));
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const keep = new Set([...currentPaths].map(path => url(path, current.files[path])));
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if (previous) for (const path of paths(previous)) {
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if (!currentPaths.has(path) || current.files[path]?.h !== previous.files[path].h) keep.add(url(path, previous.files[path]));
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}
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return keep;
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}
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function fallback(manifest, previous, path) {
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if (!manifest.files[path] || !previous?.files[path]) return null;
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const group = Object.keys(manifest.groups).find(name => manifest.groups[name].files.includes(path));
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if (!group || !previous.groups[group]?.files.includes(path) ||
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manifest.groups[group].contract !== previous.groups[group].contract) return null;
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return url(path, previous.files[path]);
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}
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async function state(cache) {
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const response = await cache.match(STATE);
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return response ? response.json() : null;
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}
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async function status(manifest, cache, { previous, activeLayout, offline = true } = {}) {
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const found = await Promise.all(blocking(manifest, previous, activeLayout).map(async path => {
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const response = await cache.match(url(path, manifest.files[path]));
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return !!response && response.headers.get('X-Asset-Hash') === manifest.files[path].h;
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}));
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const missing = found.filter(value => !value).length;
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return { ready: missing === 0, missing, version: manifest.buildTag, ...(offline ? await completeness(manifest, cache) : {}) };
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}
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// All concurrent messages/layout jobs in this worker share six download slots.
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let downloads = 0;
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const waiters = [];
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async function downloadSlot(task) {
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if (downloads >= 6) await new Promise(resolve => waiters.push(resolve));
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else downloads++;
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try { return await task(); }
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finally { const next = waiters.shift(); if (next) next(); else downloads--; }
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}
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const pendingDownloads = new Map();
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async function sharedDownload(key, task) {
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while (pendingDownloads.has(key)) await pendingDownloads.get(key).catch(() => {});
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const promise = downloadSlot(task);
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pendingDownloads.set(key, promise);
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try { return await promise; }
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finally { pendingDownloads.delete(key); }
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}
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async function syncAssets(manifest, { cache, fetchFn, concurrency = 6, attempts = 3, activeLayout, groups, all = false }) {
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const previous = (await state(cache))?.current;
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const missing = [];
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const selected = all ? paths(manifest) : groups ? [...new Set(groups.flatMap(name => manifest.groups[name]?.files || []))].sort()
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: blocking(manifest, previous, activeLayout);
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for (const path of selected) {
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const key = url(path, manifest.files[path]);
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const response = await cache.match(key);
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if (!response || response.headers.get('X-Asset-Hash') !== manifest.files[path].h) missing.push(key);
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}
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const count = missing.length;
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let failure;
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await Promise.all(Array.from({ length: Math.max(1, Math.min(6, concurrency, count)) }, async () => {
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while (missing.length) {
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const key = missing.shift();
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try { await sharedDownload(key, async () => {
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const held = await cache.match(key);
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if (held?.headers.get('X-Asset-Hash') === key.split('v=')[1]) return;
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let error;
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for (let attempt = 0; attempt < Math.min(3, attempts); attempt++) {
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const controller = new AbortController();
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const timer = setTimeout(() => controller.abort(), 30000);
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try {
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const response = await fetchFn(key, { credentials: 'same-origin', signal: controller.signal });
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if (!response.ok || response.headers.get('X-Asset-Hash') !== key.split('v=')[1]) {
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throw new Error('Asset hash mismatch: ' + key);
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}
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// Keep the timeout through body consumption, not just response headers.
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await cache.put(key, response);
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error = null;
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break;
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} catch (err) { error = err; }
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finally { clearTimeout(timer); }
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}
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if (error) throw error;
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}); } catch (error) { failure = error; }
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}
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}));
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if (failure) throw failure;
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if (!groups && !all && !(await status(manifest, cache, { previous, activeLayout, offline: false })).ready) throw new Error('Incomplete blocking assets');
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return { refreshed: count, caches: 1 };
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}
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// Verified cache entries are the durable progress journal. Counters are rebuilt
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// after worker termination or browser eviction; never trust a stored ready bit.
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async function completeness(manifest, cache) {
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const files = paths(manifest);
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const missingFiles = (await Promise.all(files.map(async path => {
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const response = await cache.match(url(path, manifest.files[path]));
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return !response || response.headers.get('X-Asset-Hash') !== manifest.files[path].h ? path : null;
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}))).filter(Boolean);
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const total = files.length;
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return { offlineReady: missingFiles.length === 0, cached: total - missingFiles.length, total, missingFiles };
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}
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const completionKey = manifest => '/__ytp_completion/' + manifest.buildTag;
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async function complete(manifest, { cache, fetchFn, cycles = 4, now = Date.now,
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sleep = ms => new Promise(resolve => setTimeout(resolve, ms)), baseDelay = 1000,
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maxDelay = 30000, notify = () => {}, force = false } = {}) {
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const key = completionKey(manifest), saved = await cache.match(key);
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let job = saved ? await saved.json() : { failures: 0, nextRetryAt: 0 };
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let snapshot = await completeness(manifest, cache);
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const publish = async running => {
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job = { ...job, ...snapshot, running, version: manifest.buildTag };
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await cache.put(key, Response.json(job));
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await notify(job);
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};
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if (snapshot.offlineReady) { job.failures = 0; job.nextRetryAt = 0; await publish(false); return job; }
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if (!force && job.nextRetryAt > now()) await sleep(Math.min(maxDelay, job.nextRetryAt - now()));
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for (let cycle = 0; cycle < cycles; cycle++) {
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await publish(true);
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let error;
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try { await syncAssets(manifest, { cache, fetchFn, all: true }); }
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catch (failure) { error = failure; }
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snapshot = await completeness(manifest, cache);
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if (snapshot.offlineReady) { job.failures = 0; job.nextRetryAt = 0; job.error = null; await publish(false); return job; }
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job.failures++;
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const delay = Math.min(maxDelay, baseDelay * 2 ** Math.min(job.failures - 1, 10));
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job.nextRetryAt = now() + delay;
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job.error = String(error?.message || 'Incomplete offline cache');
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await publish(cycle + 1 < cycles);
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if (cycle + 1 < cycles) await sleep(delay);
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}
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return job;
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}
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async function commit(manifest, cache, { previousClients, activeLayout } = {}) {
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const old = await state(cache);
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if (!(await status(manifest, cache, { previous: old?.current, activeLayout, offline: false })).ready) {
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throw new Error('Incomplete blocking assets');
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}
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const sameBuild = old?.current?.buildTag === manifest.buildTag;
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const previous = sameBuild ? old.previous : old?.current;
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const next = {
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current: manifest, previous,
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previousClients: previousClients || (sameBuild ? old.previousClients : []),
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};
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// One state write publishes the complete build and its old-tab affinity.
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await cache.put(STATE, new Response(JSON.stringify(next), { headers: { 'Content-Type': 'application/json' } }));
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const keep = retained(manifest, previous);
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for (const request of await cache.keys()) {
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const parsed = new URL(request.url);
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const key = parsed.pathname + parsed.search;
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if (parsed.searchParams.has('v') && !keep.has(key)) await cache.delete(key);
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}
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return next;
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}
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const api = { CACHE, STATE, url, paths, blocking, plan, retained, fallback, status, completeness, completionKey, complete, syncAssets, state, commit };
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if (typeof module !== 'undefined' && module.exports) module.exports = api;
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else root.AssetSyncCore = api;
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})(typeof globalThis !== 'undefined' ? globalThis : this);
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