diff --git a/nodejs/tests/no_native_dialogs.test.js b/nodejs/tests/no_native_dialogs.test.js
new file mode 100644
index 0000000..ac394ad
--- /dev/null
+++ b/nodejs/tests/no_native_dialogs.test.js
@@ -0,0 +1,45 @@
+'use strict';
+
+// Regression guard: native alert()/confirm()/prompt() calls block all further
+// browser events on the page (found live, mid browser-automation testing, on
+// directory.ejs's "Rotate Client Secret" — it froze the tab entirely) and are
+// visually inconsistent with the rest of the UI. Every call site was removed
+// in favor of app.messages.action/confirm/toast and app.modal.open; this test
+// keeps it that way.
+
+const fs = require('fs');
+const path = require('path');
+
+const ROOTS = ['views', 'public/js', 'public/lib/js'].map((d) => path.join(__dirname, '..', d));
+
+// Matches a bare alert(/confirm(/prompt( call, but not app.messages.*,
+// app.modal.*, or identifiers merely containing these words (e.g.
+// "confirmation", ".confirmed").
+const NATIVE_DIALOG_RE = /(^|[^.\w$])(alert|confirm|prompt)\s*\(/g;
+
+function walk(dir) {
+	let files = [];
+	if (!fs.existsSync(dir)) return files;
+	for (const entry of fs.readdirSync(dir, { withFileTypes: true })) {
+		const full = path.join(dir, entry.name);
+		if (entry.isDirectory()) files = files.concat(walk(full));
+		else if (/\.(ejs|js)$/.test(entry.name)) files.push(full);
+	}
+	return files;
+}
+
+test('no view or client-side script calls native alert()/confirm()/prompt()', () => {
+	const offenders = [];
+	for (const root of ROOTS) {
+		for (const file of walk(root)) {
+			const src = fs.readFileSync(file, 'utf8');
+			let m;
+			NATIVE_DIALOG_RE.lastIndex = 0;
+			while ((m = NATIVE_DIALOG_RE.exec(src))) {
+				const line = src.slice(0, m.index).split('\n').length;
+				offenders.push(`${path.relative(path.join(__dirname, '..'), file)}:${line} — ${m[2]}(`);
+			}
+		}
+	}
+	expect(offenders).toEqual([]);
+});