Merge persisted-settings verification and retain all harness documentation

frontend/settings-persist.test.js

@@ -0,0 +1,34 @@
+const test = require('node:test');
+const assert = require('node:assert/strict');
+const fs = require('node:fs');
+const vm = require('node:vm');
+const source = fs.readFileSync(__dirname + '/app.js', 'utf8');
+// Exercise the production persistence/profile functions without starting a DOM player.
+const declaration = name => source.match(new RegExp('(?:async )?function ' + name + '\\([^]*?\\n}'))[0];
+function fixture(updatedAt) {
+  const settings = { saveBeforePlay: true, autoPreload: true, layout: 'f7-swipe', eq: { preset: 'custom', g: [1,2,3,4,5] } };
+  const context = vm.createContext({ WEB: true, data: { settings, profile: { name: 'test', syncedAt: 200 } }, DEFAULT_SETTINGS: { saveBeforePlay: false, autoPreload: true, layout: 'classic' }, API: { saveData: async () => {} }, profileHeaders: () => ({}), scheduleProfilePush: () => context.pushes++, pushes: 0, fetch: async () => ({ status: 200, json: async () => ({ ok: true, name: 'test', updatedAt, data: { settings: { saveBeforePlay: false } } }) }), localStorage: { getItem: () => JSON.stringify({ settings }) } });
+  vm.runInContext([declaration('loadDataFromStorage'), declaration('applyProfileData'), declaration('pullProfileIfNewer')].join('\n'), context);
+  return context;
+}
+test('stored settings load verbatim instead of reverting to defaults', () => {
+  const c = fixture(100);
+  const loaded = vm.runInContext('loadDataFromStorage()', c);
+  assert.equal(loaded.settings.saveBeforePlay, true);
+  assert.equal(loaded.settings.layout, 'f7-swipe');
+  assert.deepEqual(JSON.parse(JSON.stringify(loaded.settings.eq.g)), [1,2,3,4,5]);
+});
+for (const updatedAt of [100,200]) test(`profile timestamp ${updatedAt} cannot overwrite local settings synced at 200`, async () => {
+  const c = fixture(updatedAt), previous = c.data.settings;
+  await vm.runInContext('pullProfileIfNewer()', c);
+  assert.equal(c.data.settings, previous);
+  assert.equal(c.pushes, 1);
+});
+test('newer profile intentionally replaces settings and restores missing defaults', async () => {
+  const c = fixture(300);
+  await vm.runInContext('pullProfileIfNewer()', c);
+  assert.equal(c.data.settings.saveBeforePlay, false);
+  assert.equal(c.data.settings.autoPreload, true);
+  assert.equal(c.data.settings.layout, 'classic');
+  assert.equal(c.data.profile.syncedAt, 300);
+});