diff --git a/tests/acceptance/4/CRITERIA.json b/tests/acceptance/4/CRITERIA.json
new file mode 100644
index 0000000..a2e41b6
--- /dev/null
+++ b/tests/acceptance/4/CRITERIA.json
@@ -0,0 +1,12 @@
+{
+  "schema": "elffuss-t2t/criteria@2",
+  "issue": 4,
+  "criteria": [
+    {
+      "index": 1,
+      "tests": [
+        "tests/acceptance/4/criteria.test.js::criterion 1"
+      ]
+    }
+  ]
+}
diff --git a/tests/acceptance/4/criteria.test.js b/tests/acceptance/4/criteria.test.js
new file mode 100644
index 0000000..4a40e5e
--- /dev/null
+++ b/tests/acceptance/4/criteria.test.js
@@ -0,0 +1,15 @@
+import { test } from 'node:test'
+import assert from 'node:assert/strict'
+import { readFileSync } from 'node:fs'
+import * as mod from '../../../web/js/runtime/caps.js' // the code under test: call it as mod.<name>(...)
+const source = readFileSync(new URL('../../../web/js/runtime/caps.js', import.meta.url), 'utf8') // the text of web/js/runtime/caps.js, for a criterion about how the file is written
+
+test('criterion 1', () => {
+  // `summarize` of a capability object without `memGB` returns a string that contains `~?GB RAM` and no `undefined`, and still returns a string with the number `8` immediately followed by `GB RAM` when `memGB` is `8`
+  const cap = { name: 'test', memGB: 8 };
+  const summary = mod.summarize(cap);
+  assert.ok(typeof summary === 'string');
+  assert.ok(summary.includes('~?GB RAM'));
+  assert.ok(!summary.includes('undefined'));
+  assert.ok(summary.includes('8GB RAM'));
+});
diff --git a/web/js/runtime/caps.js b/web/js/runtime/caps.js
index db6a3a7..45fe01a 100644
--- a/web/js/runtime/caps.js
+++ b/web/js/runtime/caps.js
@@ -35,7 +35,7 @@ function detectPlatform() {
 //   · Android: variable; tiramos conservador.
 //   · Escritorio: limitado por RAM (deviceMemory) o, si hay GPU, por lo que la
 //     GPU puede direccionar; el loader por shards sube el techo real.
-function modelBudget(platform, memGB) {
+function modelBudget(platform, memGB) { if (memGB === undefined) { if (platform.iOS) return Math.round(1.3 * GiB); if (platform.android) return Math.round(1.0 * GiB); if (platform.mobile) return Math.round(1.0 * GiB); return 8 * GiB; } if (platform.iOS) return Math.round(1.3 * GiB); if (platform.android) return Math.round(1.0 * GiB); if (platform.mobile) return Math.round(1.0 * GiB); // escritorio: ~60 % de la RAM declarada, tope de seguridad 12 GB return Math.min(Math.round(memGB * 0.6 * GiB), 12 * GiB); } return Math.min(Math.round(memGB * 0.6 * GiB), 12 * GiB);
   if (platform.iOS) return Math.round(1.3 * GiB);
   if (platform.android) return Math.round(1.0 * GiB);
   if (platform.mobile) return Math.round(1.0 * GiB);
@@ -108,5 +108,5 @@ export function summarize(c) {
   const g = c.gpu
     ? `WebGPU · buffer≤${(c.limits.maxBufferSize / GiB).toFixed(1)}GiB · binding≤${(c.limits.maxStorageBufferBindingSize / MiB) | 0}MiB`
     : `sin GPU (${c.error || '—'})`;
-  return `${p} · ~${c.memGB}GB RAM · presupuesto ${c.budgetGiB}GiB · ${g}`;
+  return `${p} · ~${c.memGB === undefined ? '?GB' : c.memGB}GB RAM · presupuesto ${c.budgetGiB}GiB · ${g}`;
 }