Tasks tab: NE Hub lists plus iCloud reminder lists where Apple exposes them

- Lists, quick add, due dates, notes, complete/reopen, delete; Home card for overdue/due today
- iCloud VTODO lists read and written over CalDAV (If-Match, edits patch the latest copy so
  priority/alarms survive); NE Hub lists work regardless
- Fix: text inside a nested VALARM was read as the task's / event's own description and then
  written back on edit; nested components are now skipped (regression tests added)

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

ics.js

@@ -162,6 +162,50 @@ function fieldsFromEvent(ev, clientTz) {
   return { ...base, allDay: false, start: wallClock(s.ms, tz), end: wallClock(endMs, tz), tz };
 }
 
+
+// ---- Tasks (VTODO). fields: { title, notes, due: '' | 'YYYY-MM-DD', done: boolean }
+function validateTodo(f) {
+  if (!f || !String(f.title || '').trim()) throw new Error('Give the task a title');
+  if (f.due && !/^\d{4}-\d{2}-\d{2}$/.test(f.due)) throw new Error('The due date is not valid');
+}
+function todoLines(f, { completed = true } = {}) {
+  const L = ['SUMMARY:' + esc(String(f.title).trim())];
+  if (f.notes) L.push('DESCRIPTION:' + esc(f.notes));
+  if (f.due) L.push('DUE;VALUE=DATE:' + f.due.replace(/-/g, ''));
+  if (f.done) { L.push('STATUS:COMPLETED', 'PERCENT-COMPLETE:100'); if (completed) L.push('COMPLETED:' + nowStamp()); }
+  else L.push('STATUS:NEEDS-ACTION');
+  return L;
+}
+function buildTodoCalendar(items) {
+  const L = ['BEGIN:VCALENDAR', 'VERSION:2.0', 'PRODID:-//NE Hub//Tasks//EN'];
+  for (const i of items) { validateTodo(i.fields); L.push('BEGIN:VTODO', 'UID:' + i.uid, 'DTSTAMP:' + nowStamp(), 'CREATED:' + nowStamp(), 'SEQUENCE:0', ...todoLines(i.fields), 'END:VTODO'); }
+  L.push('END:VCALENDAR');
+  return L.map(fold).join('\r\n') + '\r\n';
+}
+/** Edit an existing VTODO resource in place; alarms and other properties are kept. */
+function patchTodo(text, f) {
+  validateTodo(f);
+  const lines = text.replace(/\r?\n[ \t]/g, '').split(/\r?\n/).filter(l => l !== '');
+  const a = lines.indexOf('BEGIN:VTODO'), b = lines.indexOf('END:VTODO');
+  if (a < 0 || b < a) throw new Error('Could not find the task in that entry');
+  const out = []; let depth = 0, seq = 0, hadCompleted = false, sawStamp = false;
+  lines.forEach((l, i) => {
+    if (i < a || i > b) { out.push(l); return; }
+    if (i === a) { out.push(l); return; }
+    if (i === b) { out.push(...todoLines(f, { completed: !hadCompleted }), 'SEQUENCE:' + (seq + 1)); if (!sawStamp) out.push('DTSTAMP:' + nowStamp()); out.push(l); return; }
+    if (/^BEGIN:/.test(l)) { depth++; out.push(l); return; }
+    if (/^END:/.test(l)) { depth--; out.push(l); return; }
+    if (depth > 0) { out.push(l); return; }
+    const name = l.split(/[;:]/)[0].toUpperCase();
+    if (name === 'COMPLETED') { if (f.done) { hadCompleted = true; out.push(l); } return; } // keep the original completion time
+    if (['SUMMARY', 'DESCRIPTION', 'DUE', 'STATUS', 'PERCENT-COMPLETE'].includes(name)) return;
+    if (name === 'SEQUENCE') { seq = parseInt(l.split(':')[1], 10) || 0; return; }
+    if (name === 'DTSTAMP') { out.push('DTSTAMP:' + nowStamp()); sawStamp = true; return; }
+    out.push(l);
+  });
+  return out.map(fold).join('\r\n') + '\r\n';
+}
+
 const newUid = () => crypto.randomUUID() + '@nehub';
 
-module.exports = { buildVevent, buildCalendar, patchIcs, fieldsFromEvent, vtimezone, validate, newUid, wallClock, validTz };
+module.exports = { validateTodo, buildTodoCalendar, patchTodo, buildVevent, buildCalendar, patchIcs, fieldsFromEvent, vtimezone, validate, newUid, wallClock, validTz };