diff --git a/frontend-modern/src/utils/__tests__/localStorage.test.ts b/frontend-modern/src/utils/__tests__/localStorage.test.ts
new file mode 100644
index 0000000000..5ccab2460e
--- /dev/null
+++ b/frontend-modern/src/utils/__tests__/localStorage.test.ts
@@ -0,0 +1,487 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
+import { createRoot } from 'solid-js';
+import {
+  createLocalStorageBooleanSignal,
+  createLocalStorageNumberSignal,
+  createLocalStorageStringSignal,
+  STORAGE_KEYS,
+} from '@/utils/localStorage';
+
+const SYNC_EVENT = 'pulse-localstorage-sync';
+
+// createEffect defers its first run to a microtask; await this after setting up
+// or mutating a signal so the sync-to-storage effect has flushed.
+const flush = async () => {
+  await Promise.resolve();
+  await Promise.resolve();
+};
+
+type AnySignal<T> = [() => T, (v: T) => void];
+
+const disposables: Array<() => void> = [];
+
+function makeSignal<T>(factory: () => AnySignal<T>): {
+  value: () => T;
+  setValue: (v: T) => void;
+  setValueAny: (v: unknown) => void;
+  dispose: () => void;
+} {
+  let dispose!: () => void;
+  let value!: () => T;
+  let setValue!: (v: T) => void;
+  createRoot((d) => {
+    dispose = d;
+    [value, setValue] = factory() as AnySignal<T>;
+  });
+  const disposeFn = () => dispose();
+  disposables.push(disposeFn);
+  return {
+    value: () => value(),
+    setValue: (v: T) => setValue(v),
+    setValueAny: (v: unknown) => (setValue as (v: unknown) => void)(v),
+    dispose: disposeFn,
+  };
+}
+
+function dispatchCustomSync(key: string, value: string | null) {
+  window.dispatchEvent(
+    new CustomEvent(SYNC_EVENT, { detail: { key, value } }),
+  );
+}
+
+// jsdom's StorageEvent constructor rejects non-jsdom Storage instances for
+// storageArea (the shared in-memory storage from setup is a plain class). The
+// handler only reads key/newValue/storageArea, so a plain Event with those
+// props is sufficient and faithful for exercising the handler logic.
+function dispatchStorageEvent(key: string, newValue: string | null, storageArea: Storage | null) {
+  const event = new Event('storage');
+  Object.defineProperty(event, 'key', { value: key, configurable: true });
+  Object.defineProperty(event, 'newValue', { value: newValue, configurable: true });
+  Object.defineProperty(event, 'storageArea', { value: storageArea, configurable: true });
+  window.dispatchEvent(event);
+}
+
+describe('localStorage signals', () => {
+  beforeEach(() => {
+    localStorage.clear();
+  });
+
+  afterEach(() => {
+    while (disposables.length) disposables.pop()!();
+    vi.restoreAllMocks();
+  });
+
+  describe('STORAGE_KEYS', () => {
+    it('exposes the expected string keys', () => {
+      expect(STORAGE_KEYS.AUTH).toBe('pulse_auth');
+      expect(STORAGE_KEYS.AUTH_USER).toBe('pulse_auth_user');
+      expect(STORAGE_KEYS.THEME_PREFERENCE).toBe('pulseThemePreference');
+      expect(STORAGE_KEYS.SIDEBAR_COLLAPSED).toBe('sidebarCollapsed');
+      expect(STORAGE_KEYS.TEMPERATURE_UNIT).toBe('temperatureUnit');
+      expect(STORAGE_KEYS.DEBUG_MODE).toBe('pulse_debug_mode');
+      expect(STORAGE_KEYS.AUDIT_PAGE_SIZE).toBe('pulse-audit-page-size');
+    });
+
+    it('exposes a broad set of keys across feature areas', () => {
+      expect(Object.keys(STORAGE_KEYS).length).toBeGreaterThan(40);
+      expect(STORAGE_KEYS.WORKLOADS_SEARCH_HISTORY).toBe('workloadsSearchHistory');
+      expect(STORAGE_KEYS.GITHUB_STAR_SNOOZED_UNTIL).toBe('pulse-github-star-snoozed-until');
+    });
+  });
+
+  describe('createLocalStorageStringSignal', () => {
+    it('uses the default value when storage is empty', async () => {
+      const sig = makeSignal(() => createLocalStorageStringSignal('str-key', 'default'));
+
+      expect(sig.value()).toBe('default');
+    });
+
+    it('writes the default value to storage once the effect flushes', async () => {
+      const sig = makeSignal(() => createLocalStorageStringSignal('str-key', 'default'));
+      await flush();
+
+      expect(localStorage.getItem('str-key')).toBe('default');
+      sig.dispose();
+    });
+
+    it('defaults to an empty string when no default is provided', async () => {
+      const sig = makeSignal(() => createLocalStorageStringSignal('str-key'));
+      await flush();
+
+      expect(sig.value()).toBe('');
+      expect(localStorage.getItem('str-key')).toBe('');
+    });
+
+    it('reads a stored value synchronously', () => {
+      localStorage.setItem('str-key', 'stored');
+
+      const sig = makeSignal(() => createLocalStorageStringSignal('str-key', 'default'));
+
+      expect(sig.value()).toBe('stored');
+    });
+
+    it('writes to localStorage when the value changes', async () => {
+      const sig = makeSignal(() => createLocalStorageStringSignal('str-key', 'default'));
+      await flush();
+
+      sig.setValue('new-value');
+      await flush();
+
+      expect(sig.value()).toBe('new-value');
+      expect(localStorage.getItem('str-key')).toBe('new-value');
+    });
+
+    it('persists an empty string', async () => {
+      const sig = makeSignal(() => createLocalStorageStringSignal('str-key', 'default'));
+      await flush();
+
+      sig.setValue('');
+      await flush();
+
+      expect(localStorage.getItem('str-key')).toBe('');
+    });
+
+    // NOTE: setting null/undefined does NOT persist a removal. The effect removes
+    // the item and broadcasts null, but the signal's own same-tab custom-event
+    // listener receives that null broadcast and reverts the signal to its
+    // defaultValue (applyRaw maps null -> defaultValue). The effect then writes
+    // the default back to storage. See GLM_REPORT.md (suspected bug).
+    it('reverts to the default when set to null (current behavior)', async () => {
+      const sig = makeSignal(() => createLocalStorageStringSignal('str-key', 'default'));
+      await flush();
+      sig.setValue('changed');
+      await flush();
+      expect(localStorage.getItem('str-key')).toBe('changed');
+
+      sig.setValueAny(null);
+      await flush();
+
+      expect(sig.value()).toBe('default');
+      expect(localStorage.getItem('str-key')).toBe('default');
+    });
+
+    it('reverts to the default when set to undefined (current behavior)', async () => {
+      const sig = makeSignal(() => createLocalStorageStringSignal('str-key', 'default'));
+      await flush();
+      sig.setValue('changed');
+      await flush();
+      expect(localStorage.getItem('str-key')).toBe('changed');
+
+      sig.setValueAny(undefined);
+      await flush();
+
+      expect(sig.value()).toBe('default');
+      expect(localStorage.getItem('str-key')).toBe('default');
+    });
+
+    it('broadcasts a sync event when the value changes', async () => {
+      const details: Array<{ key: string; value: string | null }> = [];
+      const handler = (e: Event) => {
+        const evt = e as CustomEvent<{ key: string; value: string | null }>;
+        details.push(evt.detail);
+      };
+      window.addEventListener(SYNC_EVENT, handler);
+
+      const sig = makeSignal(() => createLocalStorageStringSignal('broadcast-key', 'def'));
+      await flush();
+      expect(details.at(-1)).toEqual({ key: 'broadcast-key', value: 'def' });
+
+      sig.setValue('updated');
+      await flush();
+      expect(details.at(-1)).toEqual({ key: 'broadcast-key', value: 'updated' });
+
+      sig.setValueAny(null);
+      await flush();
+      // A null broadcast is emitted (the clear intent), but the same-tab
+      // self-sync reverts the signal to its default (suspected bug).
+      expect(details).toContainEqual({ key: 'broadcast-key', value: null });
+      expect(details.at(-1)).toEqual({ key: 'broadcast-key', value: 'def' });
+
+      window.removeEventListener(SYNC_EVENT, handler);
+    });
+  });
+
+  describe('createLocalStorageBooleanSignal', () => {
+    const parseCases: Array<[string, boolean]> = [
+      ['true', true],
+      ['false', false],
+      ['1', false],
+      ['0', false],
+      ['TRUE', false],
+      ['True', false],
+      ['', false],
+      ['anything', false],
+    ];
+
+    it.each(parseCases)('parses stored %j as %s', (stored, expected) => {
+      localStorage.setItem('bool-key', stored);
+
+      const sig = makeSignal(() => createLocalStorageBooleanSignal('bool-key', false));
+
+      expect(sig.value()).toBe(expected);
+    });
+
+    it('defaults to false when no default is given and storage is empty', async () => {
+      const sig = makeSignal(() => createLocalStorageBooleanSignal('bool-key'));
+      await flush();
+
+      expect(sig.value()).toBe(false);
+      expect(localStorage.getItem('bool-key')).toBe('false');
+    });
+
+    it('defaults to true when provided and storage is empty', async () => {
+      const sig = makeSignal(() => createLocalStorageBooleanSignal('bool-key', true));
+      await flush();
+
+      expect(sig.value()).toBe(true);
+      expect(localStorage.getItem('bool-key')).toBe('true');
+    });
+
+    it.each([
+      [true, 'true'],
+      [false, 'false'],
+    ])('writes %s to storage as %j', async (next, expected) => {
+      const sig = makeSignal(() => createLocalStorageBooleanSignal('bool-key', false));
+      await flush();
+
+      sig.setValue(next);
+      await flush();
+
+      expect(localStorage.getItem('bool-key')).toBe(expected);
+    });
+
+    it('reverts to the default when set to null (current behavior)', async () => {
+      const sig = makeSignal(() => createLocalStorageBooleanSignal('bool-key', true));
+      await flush();
+      expect(localStorage.getItem('bool-key')).toBe('true');
+
+      sig.setValueAny(null);
+      await flush();
+
+      expect(sig.value()).toBe(true);
+      expect(localStorage.getItem('bool-key')).toBe('true');
+    });
+  });
+
+  describe('createLocalStorageNumberSignal', () => {
+    const defaultParseCases: Array<[string, number]> = [
+      ['42', 42],
+      ['3.14', 3.14],
+      ['-5', -5],
+      ['0', 0],
+      ['1e3', 1000],
+      ['0x10', 16],
+      ['', 0],
+      ['  ', 0],
+    ];
+
+    it.each(defaultParseCases)('parses stored %j as %s', (stored, expected) => {
+      localStorage.setItem('num-key', stored);
+
+      const sig = makeSignal(() => createLocalStorageNumberSignal('num-key', 7));
+
+      expect(sig.value()).toBe(expected);
+    });
+
+    it.each([
+      ['abc'],
+      ['Infinity'],
+      ['NaN'],
+    ])('falls back to the default when stored %j is not finite', (stored) => {
+      localStorage.setItem('num-key', stored);
+
+      const sig = makeSignal(() => createLocalStorageNumberSignal('num-key', 7));
+
+      expect(sig.value()).toBe(7);
+    });
+
+    it('heals an invalid stored value by writing the default back to storage', async () => {
+      localStorage.setItem('num-key', 'abc');
+
+      const sig = makeSignal(() => createLocalStorageNumberSignal('num-key', 7));
+      await flush();
+
+      expect(sig.value()).toBe(7);
+      expect(localStorage.getItem('num-key')).toBe('7');
+    });
+
+    it('defaults to 0 when no default is given and storage is empty', async () => {
+      const sig = makeSignal(() => createLocalStorageNumberSignal('num-key'));
+      await flush();
+
+      expect(sig.value()).toBe(0);
+      expect(localStorage.getItem('num-key')).toBe('0');
+    });
+
+    it.each([
+      [99, '99'],
+      [0, '0'],
+      [-3.5, '-3.5'],
+    ])('writes %s to storage as %j', async (next, expected) => {
+      const sig = makeSignal(() => createLocalStorageNumberSignal('num-key', 0));
+      await flush();
+
+      sig.setValue(next);
+      await flush();
+
+      expect(localStorage.getItem('num-key')).toBe(expected);
+    });
+
+    it('reverts to the default when set to null (current behavior)', async () => {
+      const sig = makeSignal(() => createLocalStorageNumberSignal('num-key', 5));
+      await flush();
+      expect(localStorage.getItem('num-key')).toBe('5');
+
+      sig.setValueAny(null);
+      await flush();
+
+      expect(sig.value()).toBe(5);
+      expect(localStorage.getItem('num-key')).toBe('5');
+    });
+  });
+
+  describe('cross-instance sync', () => {
+    it('keeps two signals for the same key in sync', async () => {
+      const a = makeSignal(() => createLocalStorageStringSignal('sync-key', 'def'));
+      await flush();
+      const b = makeSignal(() => createLocalStorageStringSignal('sync-key', 'def'));
+      await flush();
+
+      expect(a.value()).toBe('def');
+      expect(b.value()).toBe('def');
+
+      a.setValue('from-a');
+      await flush();
+      expect(b.value()).toBe('from-a');
+      expect(localStorage.getItem('sync-key')).toBe('from-a');
+
+      b.setValue('from-b');
+      await flush();
+      expect(a.value()).toBe('from-b');
+    });
+  });
+
+  describe('storage event sync', () => {
+    it('updates the signal from a storage event for its key', async () => {
+      const sig = makeSignal(() => createLocalStorageStringSignal('se-key', 'def'));
+      await flush();
+
+      dispatchStorageEvent('se-key', 'from-storage', window.localStorage);
+
+      expect(sig.value()).toBe('from-storage');
+    });
+
+    it('ignores storage events for other keys', async () => {
+      const sig = makeSignal(() => createLocalStorageStringSignal('se-key', 'def'));
+      await flush();
+
+      dispatchStorageEvent('other-key', 'nope', window.localStorage);
+
+      expect(sig.value()).toBe('def');
+    });
+
+    it('ignores storage events from a different storage area', async () => {
+      const sig = makeSignal(() => createLocalStorageStringSignal('se-key', 'def'));
+      await flush();
+
+      dispatchStorageEvent('se-key', 'nope', null);
+
+      expect(sig.value()).toBe('def');
+    });
+
+    it('reverts to the default when a storage event clears the key', async () => {
+      localStorage.setItem('se-key', 'present');
+      const sig = makeSignal(() => createLocalStorageStringSignal('se-key', 'def'));
+      await flush();
+      expect(sig.value()).toBe('present');
+
+      dispatchStorageEvent('se-key', null, window.localStorage);
+
+      expect(sig.value()).toBe('def');
+    });
+  });
+
+  describe('custom sync event', () => {
+    it('updates the signal from a custom sync event for its key', async () => {
+      const sig = makeSignal(() => createLocalStorageStringSignal('cs-key', 'def'));
+      await flush();
+
+      dispatchCustomSync('cs-key', 'via-custom');
+
+      expect(sig.value()).toBe('via-custom');
+    });
+
+    it('ignores custom sync events for other keys', async () => {
+      const sig = makeSignal(() => createLocalStorageStringSignal('cs-key', 'def'));
+      await flush();
+
+      dispatchCustomSync('other-key', 'nope');
+
+      expect(sig.value()).toBe('def');
+    });
+
+    it('ignores custom sync events without detail', async () => {
+      const sig = makeSignal(() => createLocalStorageStringSignal('cs-key', 'def'));
+      await flush();
+
+      window.dispatchEvent(new CustomEvent(SYNC_EVENT));
+
+      expect(sig.value()).toBe('def');
+    });
+
+    it('reverts to the default when the custom event value is null', async () => {
+      localStorage.setItem('cs-key', 'present');
+      const sig = makeSignal(() => createLocalStorageStringSignal('cs-key', 'def'));
+      await flush();
+      expect(sig.value()).toBe('present');
+
+      dispatchCustomSync('cs-key', null);
+
+      expect(sig.value()).toBe('def');
+    });
+
+    it('does not change when the custom event carries the current value', async () => {
+      const sig = makeSignal(() => createLocalStorageStringSignal('cs-key', 'def'));
+      await flush();
+
+      dispatchCustomSync('cs-key', 'def');
+
+      expect(sig.value()).toBe('def');
+    });
+  });
+
+  describe('cleanup', () => {
+    it('stops listening for sync events after disposal', async () => {
+      const sig = makeSignal(() => createLocalStorageStringSignal('cu-key', 'def'));
+      await flush();
+      expect(sig.value()).toBe('def');
+
+      sig.dispose();
+
+      dispatchCustomSync('cu-key', 'after-dispose');
+      expect(sig.value()).toBe('def');
+    });
+  });
+
+  describe('broadcast error handling', () => {
+    it('does not throw when dispatching the sync event fails', async () => {
+      const dispatchSpy = vi.spyOn(window, 'dispatchEvent').mockImplementation((event: Event) => {
+        if (event.type === SYNC_EVENT) {
+          throw new Error('dispatch failed');
+        }
+        return true;
+      });
+
+      const sig = makeSignal(() => createLocalStorageStringSignal('err-key', 'def'));
+      await flush();
+      // setItem runs before the (swallowed) broadcast error
+      expect(localStorage.getItem('err-key')).toBe('def');
+
+      sig.setValue('next');
+      await flush();
+      expect(localStorage.getItem('err-key')).toBe('next');
+
+      dispatchSpy.mockRestore();
+    });
+  });
+});
diff --git a/frontend-modern/src/utils/__tests__/logger.test.ts b/frontend-modern/src/utils/__tests__/logger.test.ts
new file mode 100644
index 0000000000..c13aa0d2f5
--- /dev/null
+++ b/frontend-modern/src/utils/__tests__/logger.test.ts
@@ -0,0 +1,197 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
+
+type LoggerModule = typeof import('@/utils/logger');
+
+describe('logger', () => {
+  let logSpy: ReturnType<typeof vi.spyOn>;
+  let warnSpy: ReturnType<typeof vi.spyOn>;
+  let errorSpy: ReturnType<typeof vi.spyOn>;
+
+  beforeEach(() => {
+    logSpy = vi.spyOn(console, 'log').mockImplementation(() => {});
+    warnSpy = vi.spyOn(console, 'warn').mockImplementation(() => {});
+    errorSpy = vi.spyOn(console, 'error').mockImplementation(() => {});
+  });
+
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
+
+  describe('in development (DEV=true)', () => {
+    let logger: LoggerModule['logger'];
+    let logError: LoggerModule['logError'];
+
+    beforeEach(async () => {
+      vi.resetModules();
+      vi.stubEnv('DEV', true);
+      const mod = await import('@/utils/logger');
+      logger = mod.logger;
+      logError = mod.logError;
+    });
+
+    afterEach(() => {
+      vi.unstubAllEnvs();
+      vi.resetModules();
+    });
+
+    it('debug logs with a [DEBUG] prefix via console.log', () => {
+      logger.debug('booting up', { phase: 1 });
+
+      expect(logSpy).toHaveBeenCalledWith('%s', '[DEBUG] booting up', { phase: 1 });
+    });
+
+    it('debug omits data gracefully (defaults to empty string)', () => {
+      logger.debug('no data');
+
+      expect(logSpy).toHaveBeenCalledWith('%s', '[DEBUG] no data', '');
+    });
+
+    const debugDataCases: Array<[string, unknown, unknown]> = [
+      ['object', { a: 1 }, { a: 1 }],
+      ['array', [1, 2], [1, 2]],
+      ['number 0', 0, 0],
+      ['false boolean', false, false],
+      ['empty string', '', ''],
+      ['null becomes empty string', null, ''],
+      ['undefined becomes empty string', undefined, ''],
+      ['NaN', NaN, NaN],
+    ];
+
+    it.each(debugDataCases)(
+      'debug passes %s through as the third console.log arg',
+      (_label, data, expected) => {
+        logger.debug('msg', data);
+
+        expect(logSpy).toHaveBeenCalledWith('%s', '[DEBUG] msg', expected);
+      },
+    );
+
+    it('info always logs in dev even without keywords', () => {
+      logger.info('just info');
+
+      expect(logSpy).toHaveBeenCalledWith('%s', '[INFO] just info', '');
+    });
+
+    it('info passes data through in dev', () => {
+      logger.info('booting', { phase: 1 });
+
+      expect(logSpy).toHaveBeenCalledWith('%s', '[INFO] booting', { phase: 1 });
+    });
+
+    it('warn always logs via console.warn with [WARN] prefix', () => {
+      logger.warn('careful', { x: 1 });
+
+      expect(warnSpy).toHaveBeenCalledWith('%s', '[WARN] careful', { x: 1 });
+    });
+
+    it('warn defaults data to empty string when omitted', () => {
+      logger.warn('careful');
+
+      expect(warnSpy).toHaveBeenCalledWith('%s', '[WARN] careful', '');
+    });
+
+    it('error always logs via console.error with [ERROR] prefix', () => {
+      const err = new Error('boom');
+      logger.error('something broke', err);
+
+      expect(errorSpy).toHaveBeenCalledWith('%s', '[ERROR] something broke', err);
+    });
+
+    it('error defaults error to empty string when omitted', () => {
+      logger.error('something broke');
+
+      expect(errorSpy).toHaveBeenCalledWith('%s', '[ERROR] something broke', '');
+    });
+
+    it('logError is an alias for logger.error', () => {
+      expect(logError).toBe(logger.error);
+
+      const err = new Error('x');
+      logError('aliased', err);
+
+      expect(errorSpy).toHaveBeenCalledWith('%s', '[ERROR] aliased', err);
+    });
+  });
+
+  describe('in production (DEV=false)', () => {
+    let logger: LoggerModule['logger'];
+
+    beforeEach(async () => {
+      vi.resetModules();
+      vi.stubEnv('DEV', false);
+      const mod = await import('@/utils/logger');
+      logger = mod.logger;
+    });
+
+    afterEach(() => {
+      vi.unstubAllEnvs();
+      vi.resetModules();
+    });
+
+    it('debug does not log in production', () => {
+      logger.debug('hello', { a: 1 });
+
+      expect(logSpy).not.toHaveBeenCalled();
+    });
+
+    const infoKeywordCases: Array<[string, boolean]> = [
+      ['connection established', true],
+      ['the operation failed', true],
+      ['an error occurred', true],
+      ['established', true],
+      ['failed', true],
+      ['error', true],
+      ['all systems nominal', false],
+      ['just info', false],
+    ];
+
+    it.each(infoKeywordCases)(
+      'info in production logs for %j? %s',
+      (message, shouldLog) => {
+        logger.info(message);
+
+        if (shouldLog) {
+          expect(logSpy).toHaveBeenCalledWith('%s', `[INFO] ${message}`, '');
+        } else {
+          expect(logSpy).not.toHaveBeenCalled();
+        }
+      },
+    );
+
+    // The keyword check uses String.includes, which is case-sensitive. Capitalized
+    // variants of the trigger words are therefore NOT surfaced in production.
+    const capitalizedKeywordCases: Array<[string]> = [
+      ['Established'],
+      ['Failed'],
+      ['Error'],
+    ];
+
+    it.each(capitalizedKeywordCases)(
+      'info in production does NOT log for capitalized keyword %j (case-sensitive match, suspected bug)',
+      (message) => {
+        logger.info(message);
+
+        expect(logSpy).not.toHaveBeenCalled();
+      },
+    );
+
+    it('info in production passes data through when a keyword matches', () => {
+      logger.info('connection established', { id: 7 });
+
+      expect(logSpy).toHaveBeenCalledWith('%s', '[INFO] connection established', { id: 7 });
+    });
+
+    it('warn still logs in production', () => {
+      logger.warn('careful');
+
+      expect(warnSpy).toHaveBeenCalledWith('%s', '[WARN] careful', '');
+    });
+
+    it('error still logs in production', () => {
+      const err = new Error('boom');
+      logger.error('broke', err);
+
+      expect(errorSpy).toHaveBeenCalledWith('%s', '[ERROR] broke', err);
+    });
+  });
+});
diff --git a/frontend-modern/src/utils/__tests__/toast.test.ts b/frontend-modern/src/utils/__tests__/toast.test.ts
new file mode 100644
index 0000000000..341454824b
--- /dev/null
+++ b/frontend-modern/src/utils/__tests__/toast.test.ts
@@ -0,0 +1,165 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
+
+vi.mock('@/utils/logger', () => ({
+  logger: {
+    debug: vi.fn(),
+    info: vi.fn(),
+    warn: vi.fn(),
+    error: vi.fn(),
+  },
+}));
+
+import { logger } from '@/utils/logger';
+import {
+  showToast,
+  showSuccess,
+  showError,
+  showErrorWithDetail,
+  showWarning,
+} from '@/utils/toast';
+
+describe('toast', () => {
+  const loggerInfo = vi.mocked(logger.info);
+
+  beforeEach(() => {
+    loggerInfo.mockReset();
+    delete (window as unknown as { showToast?: unknown }).showToast;
+  });
+
+  afterEach(() => {
+    delete (window as unknown as { showToast?: unknown }).showToast;
+  });
+
+  describe('showToast', () => {
+    it('delegates to window.showToast and returns its id when available', () => {
+      const mock = vi.fn(() => 'toast-id-1');
+      (window as unknown as { showToast: typeof mock }).showToast = mock;
+
+      const result = showToast('success', 'Saved', 'all good', 5000, 'details');
+
+      expect(mock).toHaveBeenCalledWith('success', 'Saved', 'all good', 5000, 'details');
+      expect(result).toBe('toast-id-1');
+    });
+
+    it('passes undefined for omitted args when delegating', () => {
+      const mock = vi.fn(() => 'id');
+      (window as unknown as { showToast: typeof mock }).showToast = mock;
+
+      const result = showToast('info', 'Hello');
+
+      expect(mock).toHaveBeenCalledWith('info', 'Hello', undefined, undefined, undefined);
+      expect(result).toBe('id');
+    });
+
+    it('returns undefined when window.showToast returns undefined', () => {
+      const mock = vi.fn(() => undefined);
+      (window as unknown as { showToast: typeof mock }).showToast = mock;
+
+      const result = showToast('info', 'Hello');
+
+      expect(result).toBeUndefined();
+    });
+
+    it('delegates with an empty title', () => {
+      const mock = vi.fn(() => 'id');
+      (window as unknown as { showToast: typeof mock }).showToast = mock;
+
+      showToast('info', '');
+
+      expect(mock).toHaveBeenCalledWith('info', '', undefined, undefined, undefined);
+    });
+
+    it('falls back to logger.info and returns undefined when window.showToast is missing', () => {
+      const result = showToast('error', 'Failed', 'something broke');
+
+      expect(loggerInfo).toHaveBeenCalledWith('[toast:error] Failed: something broke');
+      expect(result).toBeUndefined();
+    });
+
+    it('omits the message suffix when no message is provided (fallback)', () => {
+      showToast('warning', 'Careful');
+
+      expect(loggerInfo).toHaveBeenCalledWith('[toast:warning] Careful');
+    });
+
+    it('omits the message suffix when message is an empty string (fallback)', () => {
+      showToast('success', 'Done', '');
+
+      expect(loggerInfo).toHaveBeenCalledWith('[toast:success] Done');
+    });
+
+    it('includes the toast type in the fallback log line', () => {
+      showToast('info', 'Hi', 'msg');
+
+      expect(loggerInfo).toHaveBeenCalledWith('[toast:info] Hi: msg');
+    });
+
+    it('falls back with an empty title (fallback)', () => {
+      showToast('info', '');
+
+      expect(loggerInfo).toHaveBeenCalledWith('[toast:info] ');
+    });
+  });
+
+  describe('convenience wrappers', () => {
+    type ToastWrapper = (title: string, message?: string, duration?: number) => string | undefined;
+    const wrapperCases: Array<{ name: string; fn: ToastWrapper; type: string }> = [
+      { name: 'showSuccess', fn: showSuccess, type: 'success' },
+      { name: 'showError', fn: showError, type: 'error' },
+      { name: 'showWarning', fn: showWarning, type: 'warning' },
+    ];
+
+    it.each(wrapperCases)(
+      '$name delegates to showToast with type "$type"',
+      ({ fn, type }) => {
+        const mock = vi.fn(() => 'id');
+        (window as unknown as { showToast: typeof mock }).showToast = mock;
+
+        const result = fn('Title', 'Message', 3000);
+
+        expect(mock).toHaveBeenCalledWith(type, 'Title', 'Message', 3000, undefined);
+        expect(result).toBe('id');
+      },
+    );
+
+    it('showErrorWithDetail delegates with message undefined and detail as the 5th arg', () => {
+      const mock = vi.fn(() => 'id');
+      (window as unknown as { showToast: typeof mock }).showToast = mock;
+
+      const result = showErrorWithDetail('Boom', 'stack trace', 4000);
+
+      expect(mock).toHaveBeenCalledWith('error', 'Boom', undefined, 4000, 'stack trace');
+      expect(result).toBe('id');
+    });
+
+    it('showErrorWithDetail works without duration or detail', () => {
+      const mock = vi.fn(() => 'id');
+      (window as unknown as { showToast: typeof mock }).showToast = mock;
+
+      showErrorWithDetail('Boom');
+
+      expect(mock).toHaveBeenCalledWith('error', 'Boom', undefined, undefined, undefined);
+    });
+
+    it('passes duration=0 through to window.showToast', () => {
+      const mock = vi.fn(() => 'id');
+      (window as unknown as { showToast: typeof mock }).showToast = mock;
+
+      showSuccess('Title', 'Message', 0);
+
+      expect(mock).toHaveBeenCalledWith('success', 'Title', 'Message', 0, undefined);
+    });
+
+    it('convenience wrappers fall back to logger when the toast system is not ready', () => {
+      showSuccess('Saved', 'done');
+      showError('Failed', 'broken');
+      showWarning('Careful', 'careful');
+      showErrorWithDetail('Boom', 'trace');
+
+      expect(loggerInfo).toHaveBeenCalledWith('[toast:success] Saved: done');
+      expect(loggerInfo).toHaveBeenCalledWith('[toast:error] Failed: broken');
+      expect(loggerInfo).toHaveBeenCalledWith('[toast:warning] Careful: careful');
+      expect(loggerInfo).toHaveBeenCalledWith('[toast:error] Boom');
+    });
+  });
+});