diff --git a/src/App.characterization.test.js b/src/App.characterization.test.js
index 80c538e..edee5a2 100644
--- a/src/App.characterization.test.js
+++ b/src/App.characterization.test.js
@@ -4,48 +4,30 @@
 // Purpose: refactor (path-shape rewrite) must not change these calls.
 
 import React from 'react';
-import { render, screen, fireEvent, waitFor } from '@testing-library/react';
+import { screen, fireEvent, waitFor } from '@testing-library/react';
 import '@testing-library/jest-dom';
 import { getCalls, MOCK_DB } from './__mocks__/firebase/_mock-db';
+import { renderApp, createCampaignViaUI, selectCampaignByName } from './testHelpers';
 
-// import AFTER mocks resolve (jest auto-uses __mocks__/firebase/* via moduleNameMapper)
-import App from './App';
-
-// Helper: find first setDoc call matching path substring.
 function findCall(fn, pathSub) {
   return getCalls().find(c => c.fn === fn && (pathSub ? c.path.includes(pathSub) : true));
 }
+function findCalls(fn, pathSub) {
+  return getCalls().filter(c => c.fn === fn && (pathSub ? c.path.includes(pathSub) : true));
+}
 
-beforeEach(() => {
-  // App reads window.location at mount; ensure clean.
-  window.history.replaceState({}, '', '/');
-  window.open = jest.fn();
-  global.alert = jest.fn();
-});
-
-describe('App -> Firebase characterization: createCampaign', () => {
-  test('setDoc called with campaign path + correct payload shape', async () => {
-    render(<App />);
-
-    // Wait past auth (mock fires instantly) and campaign list load.
-    await waitFor(() => screen.getByText(/Create Campaign/i));
-
-    fireEvent.click(screen.getByRole('button', { name: /Create Campaign/i }));
-
-    // Modal: name input + create.
-    await waitFor(() => screen.getByLabelText(/Campaign Name/i));
-    fireEvent.change(screen.getByLabelText(/Campaign Name/i), { target: { value: 'Test Campaign' } });
-    fireEvent.click(screen.getByRole('button', { name: /^Create$/i }));
-
-    await waitFor(() => {
-      const call = findCall('setDoc', '/campaigns/');
-      expect(call).toBeDefined();
-    });
+// ============================================================================
+// CAMPAIGN GROUP
+// ============================================================================
 
+describe('Campaign -> Firebase', () => {
+  test('createCampaign: setDoc with campaign path + payload', async () => {
+    await renderApp();
+    const id = await createCampaignViaUI('Alpha');
     const call = findCall('setDoc', '/campaigns/');
     expect(call.path).toMatch(/campaigns\/.+$/);
     expect(call.data).toMatchObject({
-      name: 'Test Campaign',
+      name: 'Alpha',
       playerDisplayBackgroundUrl: '',
       players: [],
     });
@@ -53,17 +35,108 @@ describe('App -> Firebase characterization: createCampaign', () => {
     expect(call.data).toHaveProperty('createdAt');
   });
 
-  test('campaign path includes APP_ID namespace', async () => {
-    render(<App />);
-    await waitFor(() => screen.getByText(/Create Campaign/i));
-    fireEvent.click(screen.getByRole('button', { name: /Create Campaign/i }));
-    await waitFor(() => screen.getByLabelText(/Campaign Name/i));
-    fireEvent.change(screen.getByLabelText(/Campaign Name/i), { target: { value: 'NS Test' } });
-    fireEvent.click(screen.getByRole('button', { name: /^Create$/i }));
-
-    await waitFor(() => findCall('setDoc', '/campaigns/'));
+  test('createCampaign: path includes APP_ID namespace', async () => {
+    await renderApp();
+    await createCampaignViaUI('NS Test');
     const call = findCall('setDoc', '/campaigns/');
     expect(call.path).toContain('artifacts/');
     expect(call.path).toContain('/public/data/');
   });
+
+  test('createCampaign: optional background URL stored', async () => {
+    await renderApp();
+    fireEvent.click(screen.getByRole('button', { name: /Create Campaign/i }));
+    await waitFor(() => screen.getByLabelText(/Campaign Name/i));
+    fireEvent.change(screen.getByLabelText(/Campaign Name/i), { target: { value: 'With BG' } });
+    fireEvent.change(screen.getByLabelText(/Background URL/i), { target: { value: 'https://img.test/bg.png' } });
+    fireEvent.click(screen.getByRole('button', { name: /^Create$/i }));
+    await waitFor(() => findCall('setDoc', '/campaigns/'));
+    const call = findCall('setDoc', '/campaigns/');
+    expect(call.data.playerDisplayBackgroundUrl).toBe('https://img.test/bg.png');
+  });
+
+  test('addCharacter: updateDoc on campaign doc, players array grows', async () => {
+    await renderApp();
+    const cid = await createCampaignViaUI('Roster');
+    await selectCampaignByName('Roster');
+
+    // CharacterManager form
+    fireEvent.change(screen.getByPlaceholderText('Character name'), { target: { value: 'Brog' } });
+    fireEvent.change(screen.getByLabelText(/Default HP/i), { target: { value: '25' } });
+    fireEvent.change(screen.getByLabelText(/Init Mod/i), { target: { value: '3' } });
+    fireEvent.click(screen.getByRole('button', { name: /Add Character/i }));
+
+    await waitFor(() => findCall('updateDoc', '/campaigns/'));
+    const call = findCall('updateDoc', `/campaigns/${cid}`);
+    expect(call.data.players).toHaveLength(1);
+    expect(call.data.players[0]).toMatchObject({
+      name: 'Brog',
+      defaultMaxHp: 25,
+      defaultInitMod: 3,
+    });
+    expect(call.data.players[0]).toHaveProperty('id');
+  });
+
+  test('updateCharacter: updateDoc with updated players array', async () => {
+    await renderApp();
+    const cid = await createCampaignViaUI('EditRoster');
+    await selectCampaignByName('EditRoster');
+
+    // add one first
+    fireEvent.change(screen.getByPlaceholderText('Character name'), { target: { value: 'Old Name' } });
+    fireEvent.click(screen.getByRole('button', { name: /Add Character/i }));
+    await waitFor(() => findCall('updateDoc', '/campaigns/'));
+
+    // click edit
+    const editBtn = await screen.findByRole('button', { name: /Edit character/i });
+    fireEvent.click(editBtn);
+    await waitFor(() => screen.getByDisplayValue('Old Name'));
+    fireEvent.change(screen.getByDisplayValue('Old Name'), { target: { value: 'New Name' } });
+    // Save button is icon-only (no text); submit its form.
+    const form = screen.getByDisplayValue('New Name').closest('form');
+    fireEvent.submit(form);
+
+    await waitFor(() => {
+      const calls = findCalls('updateDoc', `/campaigns/${cid}`);
+      const last = calls[calls.length - 1];
+      expect(last.data.players[0].name).toBe('New Name');
+    });
+  });
+
+  test('deleteCharacter: updateDoc with character removed', async () => {
+    await renderApp();
+    const cid = await createCampaignViaUI('DeleteRoster');
+    await selectCampaignByName('DeleteRoster');
+
+    fireEvent.change(screen.getByPlaceholderText('Character name'), { target: { value: 'Gone' } });
+    fireEvent.click(screen.getByRole('button', { name: /Add Character/i }));
+    await waitFor(() => findCall('updateDoc', '/campaigns/'));
+
+    const delBtn = await screen.findByRole('button', { name: /Delete character/i });
+    fireEvent.click(delBtn);
+    // confirmation modal
+    fireEvent.click(screen.getByRole('button', { name: /Confirm/i }));
+
+    await waitFor(() => {
+      const calls = findCalls('updateDoc', `/campaigns/${cid}`);
+      const last = calls[calls.length - 1];
+      expect(last.data.players).toHaveLength(0);
+    });
+  });
+
+  test('deleteCampaign: deletes encounters batch + campaign doc + activeDisplay null', async () => {
+    await renderApp();
+    const cid = await createCampaignViaUI('Doomed');
+    await selectCampaignByName('Doomed');
+
+    // campaign card delete button has no aria-label; find trash by text via grid
+    const allDeletes = screen.getAllByText(/Delete/i);
+    // campaign card Delete is in card grid, last one rendered
+    fireEvent.click(allDeletes[allDeletes.length - 1]);
+    fireEvent.click(await screen.findByRole('button', { name: /Confirm/i }));
+
+    await waitFor(() => findCall('deleteDoc', `/campaigns/${cid}`));
+    const delCall = findCall('deleteDoc', `/campaigns/${cid}`);
+    expect(delCall).toBeDefined();
+  });
 });
diff --git a/src/__mocks__/firebase/firestore.js b/src/__mocks__/firebase/firestore.js
index cd62191..a8ff10b 100644
--- a/src/__mocks__/firebase/firestore.js
+++ b/src/__mocks__/firebase/firestore.js
@@ -39,7 +39,7 @@ export async function addDoc(collRef, data) {
   MOCK_DB.set(path, clone(data));
   return { id, path };
 }
-export async function writeBatch(db) {
+export function writeBatch(db) {
   const ops = [];
   return {
     set: (r, d) => ops.push({ op: 'set', path: r.path, data: clone(d) }),
diff --git a/src/testHelpers.js b/src/testHelpers.js
new file mode 100644
index 0000000..a84388e
--- /dev/null
+++ b/src/testHelpers.js
@@ -0,0 +1,37 @@
+// test helpers: drive App UI to states. Used across characterization suites.
+import React from 'react';
+import { render, screen, fireEvent, waitFor } from '@testing-library/react';
+import App from './App';
+import { MOCK_DB } from './__mocks__/firebase/_mock-db';
+
+// Render app, wait for auth + campaign list.
+export async function renderApp() {
+  window.history.replaceState({}, '', '/');
+  global.alert = jest.fn();
+  window.open = jest.fn();
+  const utils = render(<App />);
+  await waitFor(() => screen.getByRole('button', { name: /Create Campaign/i }));
+  return utils;
+}
+
+// Open create-campaign modal, fill name, submit. Returns campaign id from recorded call.
+export async function createCampaignViaUI(name = 'Test Campaign') {
+  fireEvent.click(screen.getByRole('button', { name: /Create Campaign/i }));
+  await waitFor(() => screen.getByLabelText(/Campaign Name/i));
+  fireEvent.change(screen.getByLabelText(/Campaign Name/i), { target: { value: name } });
+  fireEvent.click(screen.getByRole('button', { name: /^Create$/i }));
+  // wait for setDoc recorded
+  const { getCalls } = require('./__mocks__/firebase/_mock-db');
+  await waitFor(() => getCalls().find(c => c.fn === 'setDoc' && c.path.includes('/campaigns/')));
+  const call = getCalls().find(c => c.fn === 'setDoc' && c.path.includes('/campaigns/'));
+  return call.path.split('/').pop(); // campaign id
+}
+
+// Click campaign card by name to select it. Returns selected campaign id.
+export async function selectCampaignByName(name) {
+  const card = await waitFor(() => screen.getByText(name));
+  fireEvent.click(card);
+  await waitFor(() => screen.getByText(/Managing:/i));
+}
+
+export { MOCK_DB };