Metabolism: decision-cadence (think slower than you move) + empty-block skip; flat typed-array bytecode; WebGPU decision-layer slice (experimental) + heavy-world benchmark

metabolism/tools/gpu-check.js

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+// A browser-side validation + benchmark of the GPU decision layer.
+// Open this through the demo server (e.g. `npx vite` then /gpu-check.html)
+// or paste it into the demo console — it needs a WebGPU device, which node
+// does not have.
+//
+// It runs the SAME compiled strain programs on the CPU (the reference) and
+// on the GPU (the experiment) over identical senses, and reports the worst
+// disagreement plus the timing of both paths.
+
+import { buildSong } from '../src/song/song.js';
+import { ensureFlat, runProgram, SENSE_COUNT, GRAD_COUNT, ACTION_COUNT, REGS } from '../src/song/strains.js';
+import { GpuDecisionLayer } from '../src/sim/gpu.js';
+import { analyse } from '../src/audio/analyse.js';
+import { decodeWav, mono } from '../src/audio/wav.js';
+
+export async function gpuCheck(song) {
+    const report = { available: GpuDecisionLayer.available };
+    if (!report.available) {
+        report.note = 'no WebGPU device — the CPU path remains the simulation';
+        return report;
+    }
+    const gpu = new GpuDecisionLayer();
+    report.ready = await gpu.init();
+    if (!report.ready) { report.note = 'device request failed'; return report; }
+
+    const world = { fc: 4096, FC: 64, m: song.strains.length, strains: song.strains };
+    for (const strain of song.strains) ensureFlat(strain);
+    gpu.uploadPrograms(world);
+
+    // synthetic but plausible senses: random-ish, deterministic
+    const fc = world.fc, m = world.m;
+    const senses = new Float32Array(m * fc * SENSE_COUNT);
+    const grads = new Float32Array(m * fc * GRAD_COUNT);
+    let seed = 12345;
+    const rnd = () => (seed = (seed * 1103515245 + 12345) & 0x7fffffff) / 0x7fffffff;
+    for (let i = 0; i < senses.length; i++) senses[i] = rnd();
+    for (let i = 0; i < grads.length; i++) grads[i] = Math.sign(rnd() - 0.5);
+
+    // CPU reference
+    const cpuAct = new Float32Array(m * fc * ACTION_COUNT);
+    const t0 = performance.now();
+    for (let s = 0; s < m; s++) {
+        const strain = song.strains[s];
+        const flat = ensureFlat(strain);
+        const mem = new Float32Array(REGS);
+        for (let b = 0; b < fc; b++) {
+            const ss = senses.slice(s * fc * SENSE_COUNT + b * SENSE_COUNT,
+                s * fc * SENSE_COUNT + (b + 1) * SENSE_COUNT);
+            const gg = grads.slice(s * fc * GRAD_COUNT + b * GRAD_COUNT,
+                s * fc * GRAD_COUNT + (b + 1) * GRAD_COUNT);
+            const act = new Float32Array(ACTION_COUNT);
+            runProgram(mem, 0, ss, gg, act, flat._flatI, flat._flatF, flat._flatN);
+            for (let a = 0; a < ACTION_COUNT; a++) {
+                cpuAct[(s * fc + b) * ACTION_COUNT + a] = act[a];
+            }
+        }
+    }
+    report.cpuMs = performance.now() - t0;
+
+    // GPU run (the registers start zero; the CPU reference used zeroed mem too)
+    const t1 = performance.now();
+    const gpuAct = await gpu.decide(world, senses, grads);
+    report.gpuMs = performance.now() - t1;
+
+    let worst = 0;
+    let worstAt = -1;
+    for (let i = 0; i < cpuAct.length; i++) {
+        const d = Math.abs(cpuAct[i] - gpuAct[i]);
+        if (d > worst) { worst = d; worstAt = i; }
+    }
+    report.worstDelta = worst;
+    report.worstAt = worstAt;
+    report.verdict = worst < 1e-4 ? 'MATCH (bit-close)' : `DIVERGES (worst ${worst.toFixed(6)})`;
+    return report;
+}