// holo-gpu-device.mjs — ONE WebGPU device for the whole app (the engine, BLAKE3 verify, Bao streaming).
// Memoized: exactly one requestDevice() per page. Created with the ADAPTER'S MAX limits so a 145 MB block
// binds as a storage buffer (the default cap is 128 MB — a separate default-limits device silently produced a
// wrong hash on the embed → κ mismatch → the two-device clash). timestamp-query is requested when available.
// Sharing ONE device is what lets fetch→verify→decode coexist without contending.
let _p = null;
export function getDevice() {
  if (_p) return _p;
  _p = (async () => {
    if (typeof navigator === "undefined" || !navigator.gpu) throw new Error("no WebGPU");
    const adapter = await navigator.gpu.requestAdapter();
    const L = adapter.limits;
    const canTs = adapter.features.has("timestamp-query");
    const dev = await adapter.requestDevice({
      requiredFeatures: canTs ? ["timestamp-query"] : [],
      requiredLimits: {
        maxStorageBufferBindingSize: L.maxStorageBufferBindingSize,
        maxBufferSize: L.maxBufferSize,
        maxComputeWorkgroupsPerDimension: L.maxComputeWorkgroupsPerDimension,
      },
    });
    try { if (typeof globalThis !== "undefined") globalThis.__gpuDeviceCount = (globalThis.__gpuDeviceCount || 0) + 1; } catch (e) {}
    return { dev, adapter, canTs };
  })().catch((e) => { _p = null; throw e; });
  return _p;
}
export default { getDevice };