feat(settings): export / import your data (#114)

Settings -> General -> "Your data": Export writes one JSON file of the
account's Lotus data (synced settings, bookmarks, private notes, room names
and sections, reminders, status presets, thread notification settings,
timed mutes, soundboard (clips stay on the server), emoji packs, avatar
decoration, and this device's settings). Not messages or encryption keys:
they have their own exports, and keys are secret.

Import merges: new items are added; things that differ are listed per
category and kept unless the user picks "Use the file's". Only our own
account-data types are read from a file. Files from a newer Lotus Chat
are refused with a plain message; the version stamp leaves room to
migrate older ones.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

src/app/utils/dataExport.test.ts

@@ -0,0 +1,76 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { buildExport, mergeData, parseExport, planImport } from './dataExport';
+
+const file = buildExport({
+  userId: '@a:hs',
+  accountData: {
+    'io.lotus.bookmarks': { bookmarks: [{ id: 'b1', note: 'x' }] },
+    'io.lotus.user_notes': { notes: { '@b:hs': 'met at LAN party' } },
+    'm.direct': { secret: true },
+    'io.lotus.settings': { theme: 'dark', fontSize: 16 },
+  },
+  decoration: 'halo',
+  localSettings: { callNoiseSuppression: 'ml' },
+  now: new Date('2026-10-25T00:00:00Z'),
+});
+
+test('[#114] export keeps only our own types', () => {
+  assert.equal(file.format, 'lotus-chat-data');
+  assert.equal(file.version, 1);
+  assert.deepEqual(Object.keys(file.accountData).sort(), [
+    'io.lotus.bookmarks',
+    'io.lotus.settings',
+    'io.lotus.user_notes',
+  ]);
+  assert.equal(file.profile.decoration, 'halo');
+});
+
+test('[#114] parse: round trip, wrong files, newer versions, foreign types', () => {
+  const r = parseExport(JSON.stringify(file));
+  assert.ok(r.ok);
+  assert.equal(parseExport('nope').ok, false);
+  assert.equal(parseExport('{"format":"other"}').ok, false);
+  const newer = parseExport(JSON.stringify({ ...file, version: 2 }));
+  assert.ok(!newer.ok && /newer Lotus Chat/.test(newer.error));
+  const sneaky = parseExport(
+    JSON.stringify({ ...file, accountData: { 'm.push_rules': {}, 'io.lotus.bookmarks': {} } }),
+  );
+  assert.ok(sneaky.ok);
+  assert.deepEqual(Object.keys(sneaky.file.accountData), ['io.lotus.bookmarks']);
+});
+
+test('[#114] merge: lists by id, maps by key, conflicts kept unless preferred', () => {
+  const mine = { bookmarks: [{ id: 'b1', note: 'mine' }, { id: 'b2' }] };
+  const theirs = { bookmarks: [{ id: 'b1', note: 'theirs' }, { id: 'b3' }] };
+  const keep = mergeData(mine, theirs);
+  assert.equal(keep.added, 1);
+  assert.equal(keep.conflicts, 1);
+  assert.deepEqual(keep.value, {
+    bookmarks: [{ id: 'b1', note: 'mine' }, { id: 'b2' }, { id: 'b3' }],
+  });
+  const take = mergeData(mine, theirs, true);
+  assert.deepEqual((take.value as typeof mine).bookmarks[0], { id: 'b1', note: 'theirs' });
+
+  const notes = mergeData({ a: 1, b: 2 }, { b: 3, c: 4 });
+  assert.deepEqual(notes, { value: { a: 1, b: 2, c: 4 }, added: 1, conflicts: 1 });
+  assert.deepEqual(mergeData(undefined, { x: 1 }), { value: { x: 1 }, added: 1, conflicts: 0 });
+  assert.deepEqual(mergeData(['a'], ['a', 'b']).value, ['a', 'b']);
+});
+
+test('[#114] plan summarises per category', () => {
+  const plan = planImport(file, {
+    accountData: { 'io.lotus.settings': { theme: 'light' } },
+    decoration: null,
+    localSettings: { callNoiseSuppression: 'ml' },
+  });
+  const by = Object.fromEntries(plan.map((p) => [p.key, p]));
+  assert.deepEqual(
+    [by['io.lotus.settings'].added, by['io.lotus.settings'].conflicts],
+    [1, 1],
+    'fontSize new, theme differs',
+  );
+  assert.equal(by['io.lotus.bookmarks'].added, 1);
+  assert.equal(by['profile.decoration'].added, 1);
+  assert.deepEqual([by['local.settings'].added, by['local.settings'].conflicts], [0, 0]);
+});