decode(): report live-path GPU ms/tok for clean CPU/GPU split

qvac-gpu.js

@@ -1804,9 +1804,11 @@ export async function createQvacGPU(manifest, fetchTensor, cap = 64, eos = 2, st
         mmW(enc, B.normed, W["lm_head"], B.logits);
       }
       enc.copyBufferToBuffer(DEC.ring, base * 4, DEC.stg, 0, n * 4);
+      const _tSub = performance.now();
       dev.queue.submit([enc.finish()]);
       pos = pos0 + n;
       await DEC.stg.mapAsync(GPUMapMode.READ);
+      timing = { encode: 0, exec: (performance.now() - _tSub) / n };   // GPU+fence ms/token on the live decode path (diagnostics)
       const win = new Uint32Array(DEC.stg.getMappedRange().slice(0)).subarray(0, n); DEC.stg.unmap();
       for (let k = 0; k < n; k++) {
         if (win[k] === eos) { pos = pos0 + k; done = true; break; }   // trim + rewind: stale KV beyond pos is never read