diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3765c55..4d8db53 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 All notable changes to PWA Template will be documented in this file. This project adheres to a manual release process; update both this file and `assets/changelog.json` when shipping new versions so the in-app update summary stays accurate.
 
+## [NEXT_VERSION] - [NEXT_DATE]
+
+- Expand automated test coverage for additional edge cases so branch coverage now exceeds the 80% minimum target.
+
 ## 1.1.39 - 2026-03-18
 
 - Add extra automated test scenarios for fallback states and navigation actions so reliability checks catch more edge cases.
diff --git a/assets/changelog.json b/assets/changelog.json
index 4038380..f60b83e 100644
--- a/assets/changelog.json
+++ b/assets/changelog.json
@@ -1,4 +1,11 @@
 [
+  {
+    "version": "[NEXT_VERSION]",
+    "date": "[NEXT_DATE]",
+    "changes": [
+      "Increase automated branch coverage above 80% by adding tests for more edge-case app behavior."
+    ]
+  },
   {
     "version": "1.1.39",
     "date": "2026-03-18",
diff --git a/tests/app.coverage-extra.test.js b/tests/app.coverage-extra.test.js
index 0a4300c..179d988 100644
--- a/tests/app.coverage-extra.test.js
+++ b/tests/app.coverage-extra.test.js
@@ -20,6 +20,7 @@ describe('app coverage additions', () => {
       <button id="menu-toggle" type="button"></button>
       <button id="clearDataButton" type="button" data-action="clear-data">Clear</button>
       <button id="goSettingsButton" type="button" data-action="go-settings">Go settings</button>
+      <button id="updateButton" type="button" data-action="update-app">Check updates</button>
       <aside id="sidebar" class="-translate-x-full">
         <button class="nav-btn" data-target="welcome"></button>
         <button class="nav-btn" data-target="settings"></button>
@@ -39,6 +40,7 @@ describe('app coverage additions', () => {
       </main>
       <div id="modal" class="modal-hidden" aria-hidden="true">
         <div id="modal-body"></div>
+        <button type="button" data-action="close-modal" class="hidden">X</button>
       </div>
       <section id="changelogCard">
         <div data-changelog-list></div>
@@ -133,4 +135,246 @@ describe('app coverage additions', () => {
     expect(document.querySelector('[data-changelog-empty]').classList.contains('hidden')).toBe(false);
     expect(document.querySelector('[data-app-version]').textContent).toBe('0.0.0');
   });
+
+  test('uses alert fallback when update check cannot resolve a registration', async () => {
+    const alertSpy = jest.spyOn(window, 'alert').mockImplementation(() => {});
+    document.getElementById('modal').remove();
+    Object.defineProperty(window.navigator, 'serviceWorker', {
+      configurable: true,
+      value: {
+        getRegistration: jest.fn(async () => null),
+        ready: Promise.reject(new Error('offline')),
+        addEventListener: jest.fn(),
+        removeEventListener: jest.fn(),
+        register: jest.fn(async () => ({ unregister: jest.fn() })),
+      },
+    });
+
+    require('../assets/js/app.js');
+    document.dispatchEvent(new Event('DOMContentLoaded'));
+    document.getElementById('updateButton').click();
+    await new Promise((resolve) => setTimeout(resolve, 0));
+
+    expect(alertSpy).toHaveBeenCalledWith(
+      expect.stringContaining("couldn't reach the update service"),
+    );
+  });
+
+  test('handles malformed changelog/version responses and close-modal action', async () => {
+    const errorSpy = jest.spyOn(console, 'error').mockImplementation(() => {});
+    global.fetch = jest.fn(async (url) => {
+      if (String(url).includes('changelog')) {
+        return { ok: true, json: async () => [{ version: null, date: 'not-a-date', changes: ['x'] }] };
+      }
+      if (String(url).includes('version')) {
+        return { ok: true, json: async () => ({ version: 123 }) };
+      }
+      return { ok: false, json: async () => ({}) };
+    });
+
+    require('../assets/js/app.js');
+    document.dispatchEvent(new Event('DOMContentLoaded'));
+    await new Promise((resolve) => setTimeout(resolve, 0));
+
+    expect(document.querySelector('[data-changelog-list]').textContent).toContain('Version null');
+    expect(document.querySelector('[data-app-version]').textContent).toBe('0.0.0');
+
+    document.getElementById('updateButton').click();
+    await new Promise((resolve) => setTimeout(resolve, 0));
+    document.querySelector('[data-action="close-modal"]').click();
+    expect(document.getElementById('modal').classList.contains('modal-hidden')).toBe(true);
+    expect(errorSpy).not.toHaveBeenCalledWith(expect.stringContaining('Unable to load changelog'));
+  });
+
+  test('falls back safely when collapsed card state in storage is invalid JSON', () => {
+    localStorage.setItem('collapsedCards', '{invalid json');
+
+    expect(() => {
+      require('../assets/js/app.js');
+      document.dispatchEvent(new Event('DOMContentLoaded'));
+    }).not.toThrow();
+
+    const card = document.querySelector('[data-collapsible-id="example-card"]');
+    expect(card.classList.contains('collapsed')).toBe(false);
+  });
+
+  test('keeps sidebar closed for unknown nav target and leaves clear-data cancellable', () => {
+    require('../assets/js/app.js');
+    document.dispatchEvent(new Event('DOMContentLoaded'));
+
+    document.querySelector('#sidebar .nav-btn').dataset.target = 'missing';
+    document.querySelector('#sidebar .nav-btn').click();
+    expect(document.getElementById('welcome').classList.contains('active')).toBe(true);
+
+    document.getElementById('clearDataButton').click();
+    const cancelButton = Array.from(document.querySelectorAll('#modal button')).find(
+      (button) => button.textContent === 'Cancel',
+    );
+    cancelButton.click();
+    expect(document.getElementById('modal').classList.contains('modal-hidden')).toBe(true);
+  });
+
+  test('closes modal from overlay click and escape key while preserving stored welcome fallback', async () => {
+    localStorage.setItem('activeView', 'welcome');
+    localStorage.setItem('welcomeDisabled', '1');
+
+    require('../assets/js/app.js');
+    document.dispatchEvent(new Event('DOMContentLoaded'));
+
+    expect(document.getElementById('settings').classList.contains('active')).toBe(true);
+    document.getElementById('updateButton').click();
+    await new Promise((resolve) => setTimeout(resolve, 0));
+    expect(document.getElementById('modal').classList.contains('modal-hidden')).toBe(false);
+
+    document.getElementById('modal').dispatchEvent(new MouseEvent('click', { bubbles: true }));
+    expect(document.getElementById('modal').classList.contains('modal-hidden')).toBe(true);
+
+    document.getElementById('updateButton').click();
+    document.dispatchEvent(new KeyboardEvent('keydown', { key: 'Escape' }));
+    expect(document.getElementById('modal').classList.contains('modal-hidden')).toBe(true);
+  });
+
+  test('navigates with brand home according to welcome visibility preference', () => {
+    require('../assets/js/app.js');
+    document.dispatchEvent(new Event('DOMContentLoaded'));
+
+    document.getElementById('goSettingsButton').click();
+    expect(document.getElementById('settings').classList.contains('active')).toBe(true);
+
+    document.getElementById('brandHome').click();
+    expect(document.getElementById('welcome').classList.contains('active')).toBe(true);
+
+    document.getElementById('welcomeToggle').checked = false;
+    document.getElementById('welcomeToggle').dispatchEvent(new Event('change', { bubbles: true }));
+    document.getElementById('brandHome').click();
+    expect(document.getElementById('settings').classList.contains('active')).toBe(true);
+  });
+
+  test('ignores unsupported actions and survives storage read failures', () => {
+    const getItemSpy = jest.spyOn(Storage.prototype, 'getItem').mockImplementation(() => {
+      throw new Error('storage disabled');
+    });
+
+    require('../assets/js/app.js');
+    document.dispatchEvent(new Event('DOMContentLoaded'));
+
+    const unknownAction = document.createElement('button');
+    unknownAction.dataset.action = 'do-nothing';
+    document.body.appendChild(unknownAction);
+    unknownAction.click();
+
+    expect(document.getElementById('welcome').classList.contains('active')).toBe(true);
+    expect(getItemSpy).toHaveBeenCalled();
+  });
+
+  test('dismisses confirmation modal with Escape and unhides dedicated close button', () => {
+    require('../assets/js/app.js');
+    document.dispatchEvent(new Event('DOMContentLoaded'));
+
+    document.getElementById('clearDataButton').click();
+    expect(document.querySelector('#modal [data-action="close-modal"]').classList.contains('hidden')).toBe(
+      false,
+    );
+    document.dispatchEvent(new KeyboardEvent('keydown', { key: 'Escape' }));
+    expect(document.getElementById('modal').classList.contains('modal-hidden')).toBe(true);
+  });
+
+  test('handles failed changelog and version fetches gracefully', async () => {
+    const errorSpy = jest.spyOn(console, 'error').mockImplementation(() => {});
+    global.fetch = jest.fn(async () => {
+      throw new Error('network down');
+    });
+
+    require('../assets/js/app.js');
+    document.dispatchEvent(new Event('DOMContentLoaded'));
+    await new Promise((resolve) => setTimeout(resolve, 0));
+
+    expect(document.querySelector('[data-changelog-error]').classList.contains('hidden')).toBe(false);
+    expect(document.querySelector('[data-app-version]').textContent).toBe('0.0.0');
+    expect(errorSpy).toHaveBeenCalled();
+  });
+
+  test('sorts changelog versions using numeric comparison', async () => {
+    global.fetch = jest.fn(async (url) => {
+      if (String(url).includes('changelog')) {
+        return {
+          ok: true,
+          json: async () => [
+            { version: '1.2.0', date: '2026-01-01', changes: [] },
+            { version: '1.10.0', date: '2026-01-02', changes: [] },
+          ],
+        };
+      }
+      return { ok: true, json: async () => ({ version: '1.10.0' }) };
+    });
+
+    require('../assets/js/app.js');
+    document.dispatchEvent(new Event('DOMContentLoaded'));
+    await new Promise((resolve) => setTimeout(resolve, 0));
+
+    const headings = Array.from(document.querySelectorAll('[data-changelog-list] p'));
+    expect(headings[0].textContent).toContain('1.10.0');
+  });
+
+  test('runs confirmed clear-data flow without crashing test environment', async () => {
+    window.location.reload = jest.fn();
+    localStorage.setItem('themeChoice', 'glass');
+    sessionStorage.setItem('scratch', '1');
+
+    require('../assets/js/app.js');
+    document.dispatchEvent(new Event('DOMContentLoaded'));
+
+    document.getElementById('clearDataButton').click();
+    const confirmButton = Array.from(document.querySelectorAll('#modal button')).find(
+      (button) => button.textContent === 'Confirm',
+    );
+    confirmButton.click();
+    await new Promise((resolve) => setTimeout(resolve, 0));
+
+    expect(localStorage.getItem('themeChoice')).toBeNull();
+    expect(sessionStorage.getItem('scratch')).toBeNull();
+  });
+
+  test('swallows storage clear failures during confirmed reset flow', async () => {
+    window.location.reload = jest.fn();
+    const clearSpy = jest.spyOn(Storage.prototype, 'clear').mockImplementation(() => {
+      throw new Error('quota blocked');
+    });
+
+    require('../assets/js/app.js');
+    document.dispatchEvent(new Event('DOMContentLoaded'));
+
+    document.getElementById('clearDataButton').click();
+    const confirmButton = Array.from(document.querySelectorAll('#modal button')).find(
+      (button) => button.textContent === 'Confirm',
+    );
+    confirmButton.click();
+    await new Promise((resolve) => setTimeout(resolve, 0));
+
+    expect(clearSpy).toHaveBeenCalled();
+  });
+
+  test('falls back when refocusing update button throws', async () => {
+    Object.defineProperty(window.navigator, 'serviceWorker', {
+      configurable: true,
+      value: {
+        getRegistration: jest.fn(async () => null),
+        ready: Promise.resolve(null),
+        addEventListener: jest.fn(),
+        removeEventListener: jest.fn(),
+        register: jest.fn(async () => ({ unregister: jest.fn() })),
+      },
+    });
+
+    require('../assets/js/app.js');
+    document.dispatchEvent(new Event('DOMContentLoaded'));
+    const updateButton = document.getElementById('updateButton');
+    updateButton.focus = jest.fn(() => {
+      throw new Error('focus blocked');
+    });
+
+    updateButton.click();
+    await new Promise((resolve) => setTimeout(resolve, 0));
+    expect(updateButton.focus).toHaveBeenCalled();
+  });
 });