Let stalled benchmarks time out when progress becomes NaN

scripts/bench/lib.mjs

@@ -136,7 +136,7 @@ export async function until(fn, everyMs, stallMs) {
   for (;;) {
     const r = await fn();
     if (r === true) return;
-    if (typeof r === "number" && r !== last) { last = r; deadline = Date.now() + stallMs; }
+    if (typeof r === "number" && Number.isFinite(r) && r !== last) { last = r; deadline = Date.now() + stallMs; }
     if (Date.now() > deadline) throw new Error(`等超时：${Math.round(stallMs / 60000)} 分钟没有任何进展`);
     await sleep(everyMs);
   }

scripts/bench/until-progress.test.mjs

@@ -0,0 +1,18 @@
+import assert from "node:assert/strict";
+import { test, mock } from "node:test";
+import { until } from "./lib.mjs";
+
+test("NaN progress cannot keep renewing a stalled benchmark", async () => {
+  let now = 0;
+  let polls = 0;
+  mock.method(Date, "now", () => ++now);
+  try {
+    await assert.rejects(until(() => {
+      if (++polls > 10) throw new Error("poll guard reached");
+      return NaN;
+    }, 0, 3), /等超时/);
+    assert.ok(polls <= 10);
+  } finally {
+    mock.restoreAll();
+  }
+});