test: participant characterization (9 tests)

- Participant.characterization.test.js: addMonster (shape, initiative range, NPC), deleteParticipant, toggleActive, applyDamage, damage-to-0, heal revive, toggleCondition
- testHelpers.js: getParticipantForm (scoped), addMonsterViaUI, setupReady, startCombatViaUI

Locks participant write paths + payload shapes. Refactor guard.

src/testHelpers.js

@@ -1,9 +1,22 @@
 // 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 { render, screen, fireEvent, waitFor, within } from '@testing-library/react';
 import App from './App';
 import { MOCK_DB } from './__mocks__/firebase/_mock-db';
 
+// Scoped container: the "Add Participants" section (avoids label clashes with CharacterManager).
+export function getParticipantForm() {
+  const heading = screen.getByText('Add Participants');
+  // closest section/div wrapping the form
+  let node = heading;
+  for (let i = 0; i < 6; i++) {
+    node = node.parentElement;
+    if (!node) break;
+    if (node.querySelector('form')) return node;
+  }
+  return heading.parentElement;
+}
+
 // Render app, wait for auth + campaign list.
 export async function renderApp() {
   window.history.replaceState({}, '', '/');
@@ -53,4 +66,39 @@ export async function selectEncounterByName(name) {
   await waitFor(() => screen.getByText(/Managing Encounter:/i));
 }
 
+// Add a monster participant via the ParticipantManager form. Assumes encounter selected.
+export async function addMonsterViaUI(name = 'Goblin', maxHp = 7, initMod = 2) {
+  const form = within(getParticipantForm());
+  fireEvent.change(form.getByPlaceholderText('e.g., Dire Wolf'), { target: { value: name } });
+  fireEvent.change(form.getByLabelText(/Init Mod/i), { target: { value: String(initMod) } });
+  fireEvent.change(form.getByLabelText(/Max HP/i), { target: { value: String(maxHp) } });
+  fireEvent.click(form.getByRole('button', { name: /Add to Encounter/i }));
+  const { getCalls } = require('./__mocks__/firebase/_mock-db');
+  await waitFor(() => {
+    const calls = getCalls().filter(c => c.fn === 'updateDoc' && c.path.includes('/encounters/'));
+    const last = calls[calls.length - 1];
+    return last && last.data.participants && last.data.participants.some(p => p.name === name);
+  });
+}
+
+// Full setup: app -> campaign -> encounter selected.
+export async function setupReady(campName = 'Camp', encName = 'Enc') {
+  await renderApp();
+  await createCampaignViaUI(campName);
+  await selectCampaignByName(campName);
+  await createEncounterViaUI(encName);
+  await selectEncounterByName(encName);
+}
+
+// Start combat. Assumes encounter selected with active participants.
+export async function startCombatViaUI() {
+  fireEvent.click(screen.getByRole('button', { name: /Start Combat/i }));
+  const { getCalls } = require('./__mocks__/firebase/_mock-db');
+  await waitFor(() => {
+    const calls = getCalls().filter(c => c.fn === 'updateDoc' && c.path.includes('/encounters/'));
+    const last = calls[calls.length - 1];
+    return last && last.data.isStarted === true;
+  });
+}
+
 export { MOCK_DB };