Version history, notes on highlights and bookmarks, "you've studied this", prayer journal

- Earlier versions of a study: the server keeps compressed copies (about one per ten minutes of
  editing, the latest 30); Export shows what differs and puts one back (the replaced copy is kept)
- Notes on highlights and bookmarks: synced, merged without loss, in exports and backups
- Reader verse panel lists your studies and chunks that cover the verse, and opens them
- Prayer journal: requests, who for, linked verses, days prayed, answers; synced, in backups
  and the account export; daily prayer reminder through ntfy
- TODO.md lists the ideas not built yet

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

src/hooks/usePrayers.js

@@ -0,0 +1,74 @@
+// The prayer journal on this device, kept in step with your account. Every change is saved here at once and
+// sent to the account a moment later; signing in merges the two (the newer version of each prayer wins), so a prayer
+// added on your phone appears on your computer. Signing out clears this device's copy.
+import { useCallback, useEffect, useRef, useState } from 'react';
+import { getRemotePrayers, saveRemotePrayers } from '../syncService.js';
+import { markAnswered, markDeleted, mergePrayers, newPrayer, prayersEqual, reopen, touch, togglePrayedToday } from '../utils/prayers.js';
+import { localDateString } from '../utils/readingPlans.js';
+
+const KEY = 'prayers';
+const PUSH_DELAY_MS = 1500;
+const load = () => { try { const v = JSON.parse(localStorage.getItem(KEY) || '[]'); return Array.isArray(v) ? v : []; } catch { return []; } };
+const save = (list) => { try { localStorage.setItem(KEY, JSON.stringify(list)); } catch { /* storage unavailable */ } };
+
+export function usePrayers() {
+  const [prayers, setPrayersState] = useState(load);
+  const ref = useRef(prayers);
+  ref.current = prayers;
+  const enabledRef = useRef(false);
+  const timerRef = useRef(null);
+
+  const push = useCallback(async () => {
+    window.clearTimeout(timerRef.current);
+    if (!enabledRef.current) return;
+    const result = await saveRemotePrayers(ref.current);
+    if (result.ok) {
+      const merged = mergePrayers(ref.current, result.data?.prayers);
+      if (!prayersEqual(merged, ref.current)) { ref.current = merged; save(merged); setPrayersState(merged); }
+    }
+  }, []);
+
+  const set = useCallback((next) => {
+    ref.current = next;
+    save(next);
+    setPrayersState(next);
+    if (enabledRef.current) { window.clearTimeout(timerRef.current); timerRef.current = window.setTimeout(push, PUSH_DELAY_MS); }
+  }, [push]);
+
+  const replace = (id, fn) => set(ref.current.map((p) => (p.id === id ? fn(p) : p)));
+
+  const addPrayer = (fields) => { const p = newPrayer(fields); set([p, ...ref.current]); return p; };
+  const editPrayer = (id, patch) => replace(id, (p) => touch(p, patch));
+  const togglePrayed = (id) => replace(id, (p) => togglePrayedToday(p, localDateString()));
+  const answerPrayer = (id, note) => replace(id, (p) => markAnswered(p, note));
+  const reopenPrayer = (id) => replace(id, (p) => reopen(p));
+  // Deleting leaves a marker so the other devices drop it too; the returned function puts it back
+  const deletePrayer = (id) => {
+    const before = ref.current.find((p) => p.id === id);
+    if (!before) return () => {};
+    set(ref.current.map((p) => (p.id === id ? markDeleted(p) : p)));
+    return () => set(ref.current.map((p) => (p.id === id ? touch(before, {}) : p)));
+  };
+  // Prayers from a backup file are added; a prayer already here keeps whichever copy is newer
+  const importPrayers = (list) => set(mergePrayers(ref.current, list));
+
+  const pull = useCallback(async () => {
+    enabledRef.current = true;
+    const result = await getRemotePrayers();
+    if (!result.ok) return;
+    const merged = mergePrayers(ref.current, result.data?.prayers);
+    if (!prayersEqual(merged, ref.current)) { ref.current = merged; save(merged); setPrayersState(merged); }
+    if (!prayersEqual(merged, result.data?.prayers ?? [])) await push();
+  }, [push]);
+
+  const stop = useCallback(() => {
+    enabledRef.current = false;
+    window.clearTimeout(timerRef.current);
+    try { localStorage.removeItem(KEY); } catch { /* storage unavailable */ }
+    ref.current = [];
+    setPrayersState([]);
+  }, []);
+
+  useEffect(() => () => window.clearTimeout(timerRef.current), []);
+  return { prayers, addPrayer, editPrayer, togglePrayed, answerPrayer, reopenPrayer, deletePrayer, importPrayers, pullPrayers: pull, stopPrayers: stop };
+}