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js/worker-client.js

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+(function () {
+  'use strict';
+
+  const root = window.PixelIslandModules ||= {};
+  let worker = null;
+  let nextId = 1;
+  const pending = new Map();
+
+  function canUseWorkers() {
+    return typeof Worker === 'function';
+  }
+
+  function getWorker() {
+    if (!canUseWorkers()) return null;
+    if (worker) return worker;
+    worker = new Worker('./js/pixel-worker.js');
+    worker.onmessage = (event) => {
+      const { id, ok, result, error } = event.data || {};
+      const entry = pending.get(id);
+      if (!entry) return;
+      pending.delete(id);
+      if (ok) entry.resolve(result);
+      else entry.reject(new Error(error || 'worker_error'));
+    };
+    worker.onerror = (event) => {
+      const error = new Error(event.message || 'worker_error');
+      for (const entry of pending.values()) entry.reject(error);
+      pending.clear();
+      worker?.terminate();
+      worker = null;
+    };
+    return worker;
+  }
+
+  function request(type, payload) {
+    const target = getWorker();
+    if (!target) return Promise.reject(new Error('workers_unavailable'));
+    const id = nextId++;
+    const promise = new Promise((resolve, reject) => pending.set(id, { resolve, reject }));
+    target.postMessage({ id, type, payload });
+    return promise;
+  }
+
+  function buildPixelBlobs(assets) {
+    return request('buildPixelBlobs', {
+      assets,
+      palette: root.Palette?.PALETTE || [],
+      defaultColorCode: root.Palette?.DEFAULT_SELECTED_COLOR_CODE || 'a'
+    });
+  }
+
+  root.WorkerClient = { canUseWorkers, buildPixelBlobs };
+})();