Add deterministic tests

frontend/deterministic-tests/src/parse-concurrency.ts

@@ -0,0 +1,15 @@
+import * as os from "node:os";
+
+export function parseConcurrency(): number {
+    const args = process.argv.slice(2);
+    for (let i = 0; i < args.length; i++) {
+        if (
+            (args[i] === "--concurrency" || args[i] === "-j") &&
+            i + 1 < args.length
+        ) {
+            const n = parseInt(args[i + 1], 10);
+            if (!isNaN(n) && n > 0) return n;
+        }
+    }
+    return os.cpus().length;
+}