t

src/mapPatchWorker.js

@@ -0,0 +1,24 @@
+import { generatePatch } from "./mapPatch.js";
+import { collectTransferableBuffers } from "./transferUtils.js";
+
+self.onmessage = (event) => {
+  const { id, world, rect, options } = event.data || {};
+  try {
+    const result = generatePatch(world, rect, {
+      ...(options || {}),
+      // The worker owns this preview clone. If a multi-tile attempt fails the
+      // main thread discards the entire worker world, so a second full-size field
+      // snapshot is unnecessary and would recreate the large-patch memory spike.
+      _workerOwnedPreview: true,
+      onProgress: (progress) => self.postMessage({ id, type: "progress", progress }),
+    });
+    // The main thread owns the pre-patch world while preview generation runs.
+    // Return the worker-owned preview by transferring its buffers instead of
+    // cloning the complete padded world a second time.
+    const payload = { id, ok: true, world, result };
+    const transfer = Array.from(collectTransferableBuffers(payload));
+    self.postMessage(payload, transfer);
+  } catch (error) {
+    self.postMessage({ id, ok: false, error: error?.message || String(error), stack: error?.stack || "" });
+  }
+};