diff --git a/src/app/state/settings.ts b/src/app/state/settings.ts
index b1b744c1f..3958c1c21 100644
--- a/src/app/state/settings.ts
+++ b/src/app/state/settings.ts
@@ -369,13 +369,17 @@ export function mergePersistedSettings(
   const base = { ...defaultSettings, ...fileDefaults };
   if (rawLocalStorage === null) return base;
 
-  const parsed = JSON.parse(rawLocalStorage) as Record<string, unknown>;
-  migrateParsedLocalStorage(parsed);
-
-  return {
-    ...base,
-    ...(parsed as unknown as Settings),
-  };
+  try {
+    const parsed = JSON.parse(rawLocalStorage) as Record<string, unknown>;
+    migrateParsedLocalStorage(parsed);
+
+    return {
+      ...base,
+      ...(parsed as unknown as Settings),
+    };
+  } catch {
+    return base;
+  }
 }
 
 const MESSAGE_SPACING_VALUES = new Set<MessageSpacing>(['0', '100', '200', '300', '400', '500']);
@@ -550,15 +554,30 @@ export const baseSettings = atom<Settings>(cloneDefaultSettings());
 export function bootstrapSettingsStore(store: Store, rawSettingsDefaults: unknown): void {
   const sanitized = sanitizeSettingsDefaults(rawSettingsDefaults);
   runtimeSettingsDefaults = sanitized;
-  const merged = mergePersistedSettings(localStorage.getItem(STORAGE_KEY), sanitized);
+  let raw: string | null = null;
+  try {
+    raw = localStorage.getItem(STORAGE_KEY);
+  } catch {
+    // localStorage unavailable (e.g. Node.js 22 test environment)
+  }
+  const merged = mergePersistedSettings(raw, sanitized);
   store.set(baseSettings, merged);
 }
 
-export const getSettings = (): Settings =>
-  mergePersistedSettings(localStorage.getItem(STORAGE_KEY), runtimeSettingsDefaults);
+export const getSettings = (): Settings => {
+  try {
+    return mergePersistedSettings(localStorage.getItem(STORAGE_KEY), runtimeSettingsDefaults);
+  } catch {
+    return { ...defaultSettings, ...runtimeSettingsDefaults };
+  }
+};
 
 export const setSettings = (settings: Settings) => {
-  localStorage.setItem(STORAGE_KEY, JSON.stringify(settings));
+  try {
+    localStorage.setItem(STORAGE_KEY, JSON.stringify(settings));
+  } catch {
+    // localStorage unavailable (e.g. Node.js 22 test environment)
+  }
 };
 
 export const settingsAtom = atom<Settings, [Settings], undefined>(
diff --git a/src/app/utils/debugLogger.ts b/src/app/utils/debugLogger.ts
index 88f787328..e727fa5ab 100644
--- a/src/app/utils/debugLogger.ts
+++ b/src/app/utils/debugLogger.ts
@@ -47,8 +47,15 @@ class DebugLoggerService {
   private sentryStats = { errors: 0, warnings: 0 };
 
   constructor() {
-    // Check if debug logging is enabled from localStorage
-    this.enabled = localStorage.getItem('sable_internal_debug') === '1';
+    // Check if debug logging is enabled from localStorage.
+    // Guarded with try/catch because this module is instantiated as a singleton
+    // at import time, which in Node.js 22+ can run before a jsdom environment
+    // is ready (Node has a built-in but non-functional localStorage stub).
+    try {
+      this.enabled = localStorage.getItem('sable_internal_debug') === '1';
+    } catch {
+      this.enabled = false;
+    }
     // Load disabled breadcrumb categories
     try {
       const stored = localStorage.getItem(BREADCRUMB_DISABLED_KEY);
diff --git a/src/test/setup.ts b/src/test/setup.ts
index 7b0828bfa..28c93a12c 100644
--- a/src/test/setup.ts
+++ b/src/test/setup.ts
@@ -1 +1,29 @@
 import '@testing-library/jest-dom';
+
+// Node.js 22+ ships a built-in `localStorage` stub that throws for getItem/setItem
+// unless --localstorage-file is supplied at startup. jsdom relies on being able to
+// define window.localStorage, but Node's version can prevent that.  We install an
+// in-memory implementation unconditionally so every test environment starts with a
+// working, isolated localStorage regardless of runtime version.
+const _store = new Map<string, string>();
+const _localStorage = {
+  getItem: (key: string): string | null => _store.get(key) ?? null,
+  setItem: (key: string, value: string): void => {
+    _store.set(key, value);
+  },
+  removeItem: (key: string): void => {
+    _store.delete(key);
+  },
+  clear: (): void => {
+    _store.clear();
+  },
+  get length(): number {
+    return _store.size;
+  },
+  key: (index: number): string | null => [..._store.keys()][index] ?? null,
+};
+Object.defineProperty(globalThis, 'localStorage', {
+  value: _localStorage,
+  writable: true,
+  configurable: true,
+});