diff --git a/cypress/support/e2e.js b/cypress/support/e2e.js
index 67318bd..a093b7d 100644
--- a/cypress/support/e2e.js
+++ b/cypress/support/e2e.js
@@ -20,9 +20,11 @@
 
 // Import commands.js using ES2015 syntax:
 import "./commands";
-Cypress.on("uncaught:exception", (err, runnable) => {
-  // returning false here prevents Cypress from failing the test
-  return false;
+import { getCypressUncaughtExceptionDecision } from "./uncaughtExceptionPolicy";
+
+Cypress.on("uncaught:exception", (error) => {
+  // Ignore only known benign browser/runtime noise; fail all other app errors.
+  return getCypressUncaughtExceptionDecision(error);
 });
 
 // Alternatively you can use CommonJS syntax:
diff --git a/cypress/support/uncaughtExceptionPolicy.js b/cypress/support/uncaughtExceptionPolicy.js
new file mode 100644
index 0000000..e02a6b1
--- /dev/null
+++ b/cypress/support/uncaughtExceptionPolicy.js
@@ -0,0 +1,26 @@
+// The Lucia project.
+// Copyright 2026-2026 DSP, inc.  All rights reserved.
+// Authors:
+//   imacat.yang@dsp.im (imacat), 2026/03/08
+/**
+ * Returns whether an uncaught exception should be ignored in Cypress.
+ * @param {unknown} error - The thrown uncaught exception.
+ * @returns {boolean} True when the exception is known-benign and safe to ignore.
+ */
+export function shouldIgnoreUncaughtException(error) {
+  const message = error instanceof Error ? error.message : String(error);
+  const ignorePatterns = [
+    /ResizeObserver loop limit exceeded/i,
+    /ResizeObserver loop completed with undelivered notifications/i,
+  ];
+  return ignorePatterns.some((pattern) => pattern.test(message));
+}
+
+/**
+ * Converts ignore policy into Cypress uncaught-exception callback return value.
+ * @param {unknown} error - The thrown uncaught exception.
+ * @returns {false|undefined} False to ignore, undefined to let Cypress fail the test.
+ */
+export function getCypressUncaughtExceptionDecision(error) {
+  return shouldIgnoreUncaughtException(error) ? false : undefined;
+}
diff --git a/tests/unit/cypress/uncaughtExceptionPolicy.test.js b/tests/unit/cypress/uncaughtExceptionPolicy.test.js
new file mode 100644
index 0000000..34c4c12
--- /dev/null
+++ b/tests/unit/cypress/uncaughtExceptionPolicy.test.js
@@ -0,0 +1,31 @@
+import { describe, expect, it } from "vitest";
+import {
+  getCypressUncaughtExceptionDecision,
+  shouldIgnoreUncaughtException,
+} from "../../../cypress/support/uncaughtExceptionPolicy";
+
+describe("shouldIgnoreUncaughtException", () => {
+  it("returns true for known benign ResizeObserver errors", () => {
+    expect(
+      shouldIgnoreUncaughtException(new Error("ResizeObserver loop limit exceeded")),
+    ).toBe(true);
+  });
+
+  it("returns false for unknown runtime errors", () => {
+    expect(shouldIgnoreUncaughtException(new Error("TypeError: x is undefined"))).toBe(false);
+  });
+
+  it("returns false for Cypress handler when the error should be ignored", () => {
+    expect(
+      getCypressUncaughtExceptionDecision(
+        new Error("ResizeObserver loop completed with undelivered notifications."),
+      ),
+    ).toBe(false);
+  });
+
+  it("returns undefined for Cypress handler when the error should fail the test", () => {
+    expect(
+      getCypressUncaughtExceptionDecision(new Error("TypeError: x is undefined")),
+    ).toBeUndefined();
+  });
+});