Add Outline stage, parallel reading, offline saves, backup, sync-conflict handling and more

Study
- New Outline stage (hierarchical I./A./1. points, linked to chunks, in all exports);
  the chunk stage is now "Chunks"
- Home cards: passages shown as ranges, tags capped with "+N more"

Reader
- Side-by-side translations and a Compare tab per verse
- Typeface, line spacing, verse-number settings; text and column scale with the screen
- Highlights/bookmarks sheet with named colours (synced); BSB footnote spacing fix
- Cmd-K palette (passages, studies, notes, marks), keyboard shortcuts and "?" help

Flow and safety
- Toasts with Undo replace most confirm()/alert()
- Back/Forward move between pages
- Server refuses saves over a newer copy (409); keep-mine / use-other banner;
  opening a study no longer re-stamps it
- Latest chapter request wins when flipping quickly

Offline and data
- Save books, plan days or a whole BSB/NET for offline
- Service worker fixes: helloao /api/ URLs were skipped and responses cloned too late
- Settings: download/restore a full backup

Accessibility
- Sheets trap focus and close on Escape, skip link, focus ring, reduced motion,
  theme contrast raised to 4.5:1 (with a test)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

server/db.js

@@ -353,6 +353,12 @@ export function getProject(id, userId) {
   }
 }
 
+/** The server copy's lastEdited for a project owned by userId, or null when there isn't one. */
+export function getProjectEdited(id, userId) {
+  const row = db.prepare('SELECT last_edited AS lastEdited FROM projects WHERE id = ? AND user_id = ?').get(id, userId);
+  return row ? row.lastEdited : null;
+}
+
 /**
  * Insert or replace a project owned by userId.
  * Returns the summary, or null if the id already belongs to a different user.

server/index.js

@@ -6,7 +6,7 @@ import { randomUUID } from 'crypto';
 import { fileURLToPath } from 'url';
 import { dirname, join } from 'path';
 import {
-  initDb, getAllProjects, getProject, upsertProject, deleteProject,
+  initDb, getAllProjects, getProject, getProjectEdited, upsertProject, deleteProject,
   countUsers, createUser, getUserByEmail, getUserById, claimOrphanProjects,
   enableTotp, disableTotp, setBackupCodeHashes, setPodcastName,
   getShareToken, setShareToken, clearShareToken, getProjectByShareToken,
@@ -26,6 +26,7 @@ import { startReminderScheduler, sendTestReminder, isValidTimeZone } from './rem
 import { registerBibleRoutes } from './bibleApi.js';
 import { cleanMarks } from './readerMarks.js';
 import { cleanPrefsPatch, mergePrefs } from './prefs.js';
+import { isSaveConflict, parseBase } from './projectSync.js';
 
 // Shape returned to the client for the signed-in user (login, MFA verify, /auth/me).
 function userPayload(user) {
@@ -398,6 +399,11 @@ app.put('/api/projects/:id', requireAuth, (req, res) => {
     }
     if (body.id.length > 100) return res.status(400).json({ error: 'Invalid project id.' });
     if (body.title.length > 500) return res.status(400).json({ error: 'Project title is too long.' });
+    // Refuse to overwrite a copy another device saved after the one this device last saw
+    const stored = getProjectEdited(body.id, req.session.userId);
+    if (isSaveConflict({ stored, base: parseBase(req.get('X-Base-Edited')), force: req.query.force === '1' })) {
+      return res.status(409).json({ error: 'This study was changed on another device.', code: 'conflict', serverEdited: stored });
+    }
     const saved = upsertProject(body, req.session.userId);
     if (!saved) {
       return res.status(403).json({ error: 'That project belongs to a different account.' });

server/prefs.js

@@ -10,10 +10,20 @@ const ENUMS = {
   commentarySource: ['matthew-henry', 'john-gill', 'jamieson-fausset-brown', 'tyndale', 'adam-clarke', 'john-calvin', 'keil-delitzsch'],
 };
 const DAY_MS = 86_400_000;
+const COLOR = /^#[0-9a-fA-F]{3,8}$/;
 
 // A cleaned value, or undefined when it isn't acceptable for that preference.
 export function cleanPrefValue(key, value) {
   if (ENUMS[key]) return ENUMS[key].includes(value) ? value : undefined;
+  if (key === 'colorLabels') {
+    // What each highlight colour means to the reader: { "#fef08a": "Promises", ... }
+    if (!value || typeof value !== 'object' || Array.isArray(value)) return undefined;
+    const out = {};
+    for (const [color, label] of Object.entries(value).slice(0, 12)) {
+      if (COLOR.test(color) && typeof label === 'string' && label.trim()) out[color] = label.trim().slice(0, 30);
+    }
+    return out;
+  }
   if (key === 'position') {
     if (!value || typeof value !== 'object') return undefined;
     const book = String(value.book ?? '').toUpperCase();

server/projectSync.js

@@ -0,0 +1,18 @@
+// Stops one device from silently overwriting a study another device has saved since. The browser sends
+// the `lastEdited` of the server copy it last saw (X-Base-Edited); if the server's copy has moved past
+// that, the save is refused with 409 and the person chooses whose version to keep.
+
+// stored: the server copy's lastEdited (null when there is none); base: what the client last saw
+// (null/undefined when it never synced this study); force: the person chose "keep mine".
+export function isSaveConflict({ stored, base, force = false }) {
+  if (force || stored == null) return false;
+  if (!Number.isFinite(base)) return false; // a device that never saw the server's copy has nothing to compare
+  return stored > base;
+}
+
+// Reads the base header; anything that isn't a plain number is treated as "unknown".
+export function parseBase(header) {
+  if (header == null || header === '') return null;
+  const n = Number(header);
+  return Number.isFinite(n) ? n : null;
+}

server/projectSync.test.js

@@ -0,0 +1,24 @@
+import { expect, test } from 'vitest';
+import { isSaveConflict, parseBase } from './projectSync.js';
+
+test('a save is fine when the server copy is no newer than what the device last saw', () => {
+  expect(isSaveConflict({ stored: 100, base: 100 })).toBe(false);
+  expect(isSaveConflict({ stored: 90, base: 100 })).toBe(false);
+});
+
+test('a save conflicts when another device saved after the one this device last saw', () => {
+  expect(isSaveConflict({ stored: 200, base: 100 })).toBe(true);
+});
+
+test('first saves, unknown bases and "keep mine" never conflict', () => {
+  expect(isSaveConflict({ stored: null, base: 100 })).toBe(false);
+  expect(isSaveConflict({ stored: 200, base: null })).toBe(false);
+  expect(isSaveConflict({ stored: 200, base: 100, force: true })).toBe(false);
+});
+
+test('reads the base header', () => {
+  expect(parseBase('1700000000000')).toBe(1700000000000);
+  expect(parseBase('')).toBeNull();
+  expect(parseBase(undefined)).toBeNull();
+  expect(parseBase('abc')).toBeNull();
+});

server/readerMarks.js

@@ -30,10 +30,13 @@ export function cleanMarks(body) {
       if (!int(h.startOffset, 0, 5000) || !int(h.endOffset, 1, 5000) || h.endOffset <= h.startOffset) continue;
       if (typeof h.color !== 'string' || !COLOR.test(h.color)) continue;
       seen.add(h.id);
-      highlights.push({
+      const entry = {
         id: h.id, book: String(h.book).toUpperCase(), chapter: h.chapter, verse: h.verse,
         startOffset: h.startOffset, endOffset: h.endOffset, color: h.color,
-      });
+      };
+      // The highlighted words, kept so lists of highlights can show them without loading the chapter
+      if (typeof h.text === 'string' && h.text.length > 0) entry.text = h.text.slice(0, 500);
+      highlights.push(entry);
     }
   }
   return { bookmarks, highlights };