(() => {
  "use strict";

  // Storage is namespaced per account so two people sharing a browser (or one
  // person logging out and back in as someone else) never see each other's
  // cached events/profile. currentUser is set by the auth gate before the app
  // boots, so these are only ever called once a user is known.
  let currentUser = null;
  const eventsKey = () => `puppy-tracker:${currentUser.id}:events:v1`;
  const configKey = () => `puppy-tracker:${currentUser.id}:config:v1`;
  const SYNC_URL = "api/events/sync";
  const SYNC_DEBOUNCE_MS = 1200;
  const SYNC_POLL_MS = 60_000;

  const EVENT_LABELS = {
    "sleep-start": "Sleep start",
    "sleep-end":   "Sleep end",
    "eat":         "Ate",
    "pee":         "Pee",
    "poo":         "Poo",
    "weight":      "Weigh-in",
  };

  // ---------- photos: IndexedDB store ----------
  // Schema: object store `photos` keyed by `id`, value `{id, blob, uploaded}`.
  // - Photos taken locally are written with uploaded:false and queued for upload.
  // - Photos fetched from server are cached with uploaded:true (server is source-of-truth).
  const PHOTO_DB = "puppy-tracker";
  const PHOTO_STORE = "photos";
  let photoDB = null;

  function openPhotoDB() {
    if (photoDB) return Promise.resolve(photoDB);
    return new Promise((resolve, reject) => {
      const req = indexedDB.open(PHOTO_DB, 1);
      req.onupgradeneeded = (e) => {
        const db = e.target.result;
        if (!db.objectStoreNames.contains(PHOTO_STORE)) {
          db.createObjectStore(PHOTO_STORE, { keyPath: "id" });
        }
      };
      req.onsuccess = () => { photoDB = req.result; resolve(photoDB); };
      req.onerror   = () => reject(req.error);
    });
  }

  async function putPhoto(id, blob, uploaded) {
    const db = await openPhotoDB();
    return new Promise((resolve, reject) => {
      const tx = db.transaction(PHOTO_STORE, "readwrite");
      tx.objectStore(PHOTO_STORE).put({ id, blob, uploaded });
      tx.oncomplete = () => resolve();
      tx.onerror    = () => reject(tx.error);
    });
  }

  async function getPhoto(id) {
    const db = await openPhotoDB();
    return new Promise((resolve, reject) => {
      const tx  = db.transaction(PHOTO_STORE, "readonly");
      const req = tx.objectStore(PHOTO_STORE).get(id);
      req.onsuccess = () => resolve(req.result || null);
      req.onerror   = () => reject(req.error);
    });
  }

  async function getAllPhotos() {
    const db = await openPhotoDB();
    return new Promise((resolve, reject) => {
      const tx  = db.transaction(PHOTO_STORE, "readonly");
      const req = tx.objectStore(PHOTO_STORE).getAll();
      req.onsuccess = () => resolve(req.result || []);
      req.onerror   = () => reject(req.error);
    });
  }

  async function deletePhoto(id) {
    const db = await openPhotoDB();
    return new Promise((resolve, reject) => {
      const tx = db.transaction(PHOTO_STORE, "readwrite");
      tx.objectStore(PHOTO_STORE).delete(id);
      tx.oncomplete = () => resolve();
      tx.onerror    = () => reject(tx.error);
    });
  }

  // Resize an image File to a max dimension and return a JPEG Blob.
  function resizeImage(file, maxDim = 1600, quality = 0.85) {
    return new Promise((resolve, reject) => {
      const img = new Image();
      const url = URL.createObjectURL(file);
      img.onload = () => {
        URL.revokeObjectURL(url);
        const scale = Math.min(1, maxDim / Math.max(img.naturalWidth, img.naturalHeight));
        const w = Math.max(1, Math.round(img.naturalWidth  * scale));
        const h = Math.max(1, Math.round(img.naturalHeight * scale));
        const canvas = document.createElement("canvas");
        canvas.width = w; canvas.height = h;
        canvas.getContext("2d").drawImage(img, 0, 0, w, h);
        canvas.toBlob(
          (blob) => blob ? resolve(blob) : reject(new Error("toBlob returned null")),
          "image/jpeg",
          quality,
        );
      };
      img.onerror = () => { URL.revokeObjectURL(url); reject(new Error("image load failed")); };
      img.src = url;
    });
  }

  async function uploadPhotoBlob(id, blob) {
    const form = new FormData();
    form.append("id", id);
    form.append("file", blob, `${id}.jpg`);
    const res = await fetch("api/photos", { method: "POST", body: form });
    if (!res.ok) throw new Error(`upload HTTP ${res.status}`);
  }

  async function syncPhotos() {
    if (!navigator.onLine) return;
    const all = await getAllPhotos();
    for (const p of all) {
      if (p.uploaded) continue;
      try {
        await uploadPhotoBlob(p.id, p.blob);
        await putPhoto(p.id, p.blob, true);
      } catch (err) {
        console.warn("photo upload failed", p.id, err);
        // leave queued; next sync will retry
      }
    }
  }

  // Resolve a photoId to a displayable URL. Prefers local cache; falls back
  // to the server URL (the SW will cache it transparently). Returns null if
  // we have nothing and the server doesn't either.
  const photoURLCache = new Map(); // id -> object URL (lifetime = page session)
  async function photoSrc(id) {
    if (!id) return null;
    if (photoURLCache.has(id)) return photoURLCache.get(id);
    const local = await getPhoto(id);
    if (local && local.blob) {
      const url = URL.createObjectURL(local.blob);
      photoURLCache.set(id, url);
      return url;
    }
    // Fall back to server URL — let the browser/SW cache it. Also opportunistically
    // pull it into IndexedDB so cold-offline-loads still see it.
    if (navigator.onLine) {
      try {
        const res = await fetch(`api/photos/${encodeURIComponent(id)}`);
        if (res.ok) {
          const blob = await res.blob();
          await putPhoto(id, blob, true);
          const url = URL.createObjectURL(blob);
          photoURLCache.set(id, url);
          return url;
        }
      } catch (_) { /* fall through */ }
    }
    return null;
  }

  // crypto.randomUUID() is only exposed in secure contexts (HTTPS / localhost),
  // so over plain HTTP on the LAN we need a fallback. crypto.getRandomValues
  // is available everywhere; Math.random is the last resort.
  function uuid() {
    if (typeof crypto !== "undefined" && typeof crypto.randomUUID === "function") {
      return crypto.randomUUID();
    }
    if (typeof crypto !== "undefined" && typeof crypto.getRandomValues === "function") {
      const b = new Uint8Array(16);
      crypto.getRandomValues(b);
      b[6] = (b[6] & 0x0f) | 0x40; // version 4
      b[8] = (b[8] & 0x3f) | 0x80; // variant 10
      const h = [...b].map(x => x.toString(16).padStart(2, "0"));
      return `${h.slice(0,4).join("")}-${h.slice(4,6).join("")}-${h.slice(6,8).join("")}-${h.slice(8,10).join("")}-${h.slice(10,16).join("")}`;
    }
    return `x-${Date.now().toString(16)}-${Math.random().toString(16).slice(2, 10)}`;
  }

  // ---------- storage ----------
  // Internal "raw" storage includes deleted tombstones; UI uses live().
  function loadAll() {
    try {
      const raw = localStorage.getItem(eventsKey());
      if (!raw) return [];
      const parsed = JSON.parse(raw);
      if (!Array.isArray(parsed)) return [];
      // Backfill updatedAt for events written by an older client version.
      return parsed.map(e => ({
        ...e,
        updatedAt: Number.isFinite(e.updatedAt) ? e.updatedAt : (e.at || Date.now()),
      }));
    } catch {
      return [];
    }
  }

  function saveAll(events) {
    localStorage.setItem(eventsKey(), JSON.stringify(events));
  }

  function live() {
    return loadAll().filter(e => !e.deleted);
  }

  // ---------- config (puppy name + birthday) ----------
  // The shared profile lives on the host so every client sees the same values.
  // localStorage is just a cache for instant paint + offline; the server is the
  // source of truth, reconciled by last-write-wins on updatedAt (see syncConfig).
  function loadConfig() {
    try {
      const parsed = JSON.parse(localStorage.getItem(configKey()));
      if (!parsed || typeof parsed !== "object") return { name: "", birthday: "", updatedAt: 0 };
      return {
        name: parsed.name || "",
        birthday: parsed.birthday || "",
        updatedAt: Number.isFinite(parsed.updatedAt) ? parsed.updatedAt : 0,
      };
    } catch {
      return { name: "", birthday: "", updatedAt: 0 };
    }
  }

  function saveConfig(cfg) {
    localStorage.setItem(configKey(), JSON.stringify(cfg));
  }

  // Age in whole days / weeks / calendar months from a "YYYY-MM-DD" birthday,
  // measured at `at` (defaults to now — pass a weigh-in's timestamp for its age
  // at that point). Returns null for a missing/invalid birthday or a date before it.
  function ageParts(birthday, at) {
    if (!birthday) return null;
    const [y, mo, d] = birthday.split("-").map(Number);
    if (!y || !mo || !d) return null;
    const birth = startOfDay(new Date(y, mo - 1, d));
    const ref   = startOfDay(new Date(Number.isFinite(at) ? at : Date.now()));
    if (birth > ref) return null;
    const days  = Math.floor((ref - birth) / 86_400_000);
    const weeks = Math.floor(days / 7);
    let months = (ref.getFullYear() - birth.getFullYear()) * 12 +
                 (ref.getMonth() - birth.getMonth());
    if (ref.getDate() < birth.getDate()) months--;
    if (months < 0) months = 0;
    return { days, weeks, months };
  }

  function formatAge(birthday, at) {
    const a = ageParts(birthday, at);
    if (!a) return "";
    const wk = `${a.weeks} week${a.weeks === 1 ? "" : "s"}`;
    if (a.months < 1) return `${wk} old`;
    const mo = `${a.months} month${a.months === 1 ? "" : "s"}`;
    return `${wk} · ${mo} old`;
  }

  function addEvent(type, note, at, photoId, weight) {
    const events = loadAll();
    const now = Date.now();
    events.push({
      id: uuid(),
      type,
      at: Number.isFinite(at) ? at : now,
      note: note || "",
      photoId: photoId || "",
      weight: Number.isFinite(weight) ? weight : undefined,
      updatedAt: now,
    });
    saveAll(events);
    scheduleSync();
    render();
  }

  function updateEvent(id, patch) {
    const events = loadAll().map(e =>
      e.id === id ? { ...e, ...patch, updatedAt: Date.now() } : e
    );
    saveAll(events);
    scheduleSync();
    render();
  }

  function deleteEvent(id) {
    // Soft-delete so the deletion can propagate via sync.
    const events = loadAll().map(e =>
      e.id === id ? { ...e, deleted: true, updatedAt: Date.now() } : e
    );
    saveAll(events);
    scheduleSync();
    render();
  }

  // ---------- helpers ----------
  function ymd(date) {
    const y = date.getFullYear();
    const m = String(date.getMonth() + 1).padStart(2, "0");
    const d = String(date.getDate()).padStart(2, "0");
    return `${y}-${m}-${d}`;
  }

  function startOfDay(date) {
    const d = new Date(date);
    d.setHours(0, 0, 0, 0);
    return d;
  }

  function endOfDay(date) {
    const d = new Date(date);
    d.setHours(23, 59, 59, 999);
    return d;
  }

  function formatTime(ts) {
    return new Date(ts).toLocaleTimeString([], { hour: "2-digit", minute: "2-digit", hour12: false });
  }

  const pad2 = n => String(n).padStart(2, "0");
  function toDateInput(ts) {
    const d = new Date(ts);
    return `${d.getFullYear()}-${pad2(d.getMonth() + 1)}-${pad2(d.getDate())}`;
  }
  function toTimeInput(ts) {
    const d = new Date(ts);
    return `${pad2(d.getHours())}:${pad2(d.getMinutes())}`;
  }
  function fromDateTimeInputs(dateStr, timeStr) {
    if (!dateStr || !timeStr) return NaN;
    const [y, mo, d] = dateStr.split("-").map(Number);
    const [h, mi]    = timeStr.split(":").map(Number);
    const t = new Date(y, mo - 1, d, h, mi).getTime();
    return Number.isFinite(t) ? t : NaN;
  }

  function formatDuration(ms) {
    if (ms <= 0) return "0m";
    const totalMin = Math.round(ms / 60000);
    const h = Math.floor(totalMin / 60);
    const m = totalMin % 60;
    if (h === 0) return `${m}m`;
    return `${h}h ${m}m`;
  }

  // kg with up to 2 decimals, trailing zeros stripped (5.20 -> "5.2 kg").
  function formatWeight(kg) {
    return `${Math.round(kg * 100) / 100} kg`;
  }

  function formatRelative(ts) {
    if (!ts) return "—";
    const diff = Date.now() - ts;
    if (diff < 60_000) return "just now";
    if (diff < 3_600_000) return `${Math.floor(diff / 60_000)}m ago`;
    if (diff < 86_400_000) {
      const h = Math.floor(diff / 3_600_000);
      const m = Math.floor((diff % 3_600_000) / 60_000);
      return m ? `${h}h ${m}m ago` : `${h}h ago`;
    }
    const d = Math.floor(diff / 86_400_000);
    return `${d}d ago`;
  }

  function eventsForDay(events, day) {
    const from = startOfDay(day).getTime();
    const to = endOfDay(day).getTime();
    return events
      .filter(e => e.at >= from && e.at <= to)
      .sort((a, b) => a.at - b.at);
  }

  // Calculate sleep time within a given day. Sleep intervals are derived from
  // consecutive sleep-start → sleep-end pairs across the whole event log, and
  // clipped to the day window. Unmatched sleep-start = ongoing sleep (clipped to now).
  function sleepMsInRange(events, fromTs, toTs) {
    const sorted = [...events].sort((a, b) => a.at - b.at);
    const intervals = [];
    let openStart = null;
    for (const e of sorted) {
      if (e.type === "sleep-start" && openStart === null) {
        openStart = e.at;
      } else if (e.type === "sleep-end" && openStart !== null) {
        intervals.push([openStart, e.at]);
        openStart = null;
      }
    }
    if (openStart !== null) intervals.push([openStart, Date.now()]);

    let total = 0;
    for (const [start, end] of intervals) {
      const s = Math.max(start, fromTs);
      const ePt = Math.min(end, toTs);
      if (ePt > s) total += ePt - s;
    }
    return total;
  }

  function isCurrentlyAsleep(events) {
    const sorted = [...events].sort((a, b) => a.at - b.at);
    let asleep = false;
    for (const e of sorted) {
      if (e.type === "sleep-start") asleep = true;
      else if (e.type === "sleep-end") asleep = false;
    }
    return asleep;
  }

  // Current state derived from the *latest* sleep event. Used by the live
  // counter at the top of the page.
  function currentSleepState(events) {
    let latest = null;
    for (const e of events) {
      if (e.type !== "sleep-start" && e.type !== "sleep-end") continue;
      if (!latest || e.at > latest.at) latest = e;
    }
    if (!latest) return { state: null, since: 0 };
    return {
      state: latest.type === "sleep-start" ? "asleep" : "awake",
      since: latest.at,
    };
  }

  function formatCounter(ms) {
    if (ms < 0) ms = 0;
    const totalSec = Math.floor(ms / 1000);
    const h  = Math.floor(totalSec / 3600);
    const m  = Math.floor((totalSec % 3600) / 60);
    const s  = totalSec % 60;
    const pp = n => String(n).padStart(2, "0");
    return h > 0 ? `${h}:${pp(m)}:${pp(s)}` : `${m}:${pp(s)}`;
  }

  function lastEventOfType(events, type) {
    let latest = null;
    for (const e of events) {
      if (e.type === type && (!latest || e.at > latest.at)) latest = e;
    }
    return latest;
  }

  // Wake windows: time between a sleep-end and the next sleep-start. The final
  // sleep-end with no following sleep-start = ongoing/open wake window.
  function wakeWindows(events) {
    const sorted = events
      .filter(e => e.type === "sleep-start" || e.type === "sleep-end")
      .sort((a, b) => a.at - b.at);
    const out = [];
    let waking = null;
    for (const e of sorted) {
      if (e.type === "sleep-end") {
        waking = e.at;
      } else if (e.type === "sleep-start" && waking !== null) {
        out.push({ start: waking, end: e.at, ongoing: false });
        waking = null;
      }
    }
    if (waking !== null) out.push({ start: waking, end: Date.now(), ongoing: true });
    return out;
  }

  // Sleep windows: each sleep-start → next sleep-end pair. An unmatched
  // sleep-start = ongoing/open sleep window.
  function sleepWindows(events) {
    const sorted = events
      .filter(e => e.type === "sleep-start" || e.type === "sleep-end")
      .sort((a, b) => a.at - b.at);
    const out = [];
    let sleeping = null;
    for (const e of sorted) {
      if (e.type === "sleep-start") {
        sleeping = e.at;
      } else if (e.type === "sleep-end" && sleeping !== null) {
        out.push({ start: sleeping, end: e.at, ongoing: false });
        sleeping = null;
      }
    }
    if (sleeping !== null) out.push({ start: sleeping, end: Date.now(), ongoing: true });
    return out;
  }

  function sleepWindowsForDay(events, day) {
    const dayStart = startOfDay(day).getTime();
    const dayEnd   = endOfDay(day).getTime();
    const today    = ymd(new Date()) === ymd(day);
    // Keep the overlap filter so windows show on every day they touch, but
    // display the *actual* start/end — a sleep from 23:00 yesterday to 07:00
    // today should show as "23:00 – 07:00 (8h)", not clipped at midnight.
    return sleepWindows(events)
      .filter(w => w.start <= dayEnd && w.end >= dayStart)
      .map(w => ({ start: w.start, end: w.end, ongoing: w.ongoing && today }));
  }

  // Wake windows that overlap the given day, clipped to that day for display.
  // Only mark a window as "ongoing" if the selected day is today.
  function wakeWindowsForDay(events, day) {
    const dayStart = startOfDay(day).getTime();
    const dayEnd   = endOfDay(day).getTime();
    const today    = ymd(new Date()) === ymd(day);
    // Same untrimmed-times policy as sleep windows: show the real start/end
    // even if part of the window falls outside the selected day.
    return wakeWindows(events)
      .filter(w => w.start <= dayEnd && w.end >= dayStart)
      .map(w => ({ start: w.start, end: w.end, ongoing: w.ongoing && today }));
  }

  // ---------- rendering ----------
  const dayPicker  = document.getElementById("day-picker");
  const eventList  = document.getElementById("event-list");
  const emptyState = document.getElementById("empty-state");
  const statusEl   = document.getElementById("online-status");

  function selectedDay() {
    const v = dayPicker.value;
    if (v) {
      const [y, m, d] = v.split("-").map(Number);
      return new Date(y, m - 1, d);
    }
    return new Date();
  }

  function renderStats(events) {
    const day = selectedDay();
    const from = startOfDay(day).getTime();
    const today = ymd(new Date()) === ymd(day);
    const to = today ? Date.now() : endOfDay(day).getTime();

    const sleepMs = sleepMsInRange(events, from, to);
    const awakeMs = Math.max(0, (to - from) - sleepMs);

    const dayEvents = eventsForDay(events, day);
    const count = (t) => dayEvents.filter(e => e.type === t).length;

    document.getElementById("stat-sleep").textContent = formatDuration(sleepMs);
    document.getElementById("stat-awake").textContent = formatDuration(awakeMs);
    document.getElementById("stat-meals").textContent = count("eat");
    document.getElementById("stat-pees").textContent  = count("pee");
    document.getElementById("stat-poos").textContent  = count("poo");
  }

  // Gaps (ms) between consecutive events of `type` logged within the last
  // `days` days, sorted ascending. These intervals are what tell you how
  // often the puppy needs to go out.
  function gapsBetween(events, type, days = 7) {
    const cutoff = startOfDay(new Date());
    cutoff.setDate(cutoff.getDate() - (days - 1));
    const from = cutoff.getTime();
    const times = events
      .filter(e => e.type === type && e.at >= from)
      .map(e => e.at)
      .sort((a, b) => a - b);
    const gaps = [];
    for (let i = 1; i < times.length; i++) gaps.push(times[i] - times[i - 1]);
    return gaps.sort((a, b) => a - b);
  }

  // Median is used for the "typical" gap because it ignores the single long
  // overnight gap each day, so it reflects real daytime frequency.
  function median(sorted) {
    if (sorted.length === 0) return null;
    const mid = Math.floor(sorted.length / 2);
    return sorted.length % 2 ? sorted[mid] : (sorted[mid - 1] + sorted[mid]) / 2;
  }

  function renderTiming(events) {
    const peeGaps = gapsBetween(events, "pee");
    const pooGaps = gapsBetween(events, "poo");
    const show = (id, ms) => {
      document.getElementById(id).textContent = ms == null ? "—" : formatDuration(ms);
    };
    show("gap-pee",     median(peeGaps));
    show("gap-pee-min", peeGaps[0] ?? null);
    show("gap-poo",     median(pooGaps));
    show("gap-poo-min", pooGaps[0] ?? null);

    const hint = document.getElementById("timing-hint");
    const typicalPee = median(peeGaps);
    if (typicalPee != null) {
      hint.textContent =
        `Based on ${peeGaps.length} pee gap${peeGaps.length === 1 ? "" : "s"}. ` +
        `Aim to take the puppy out a little before the typical ${formatDuration(typicalPee)} mark.`;
    } else {
      hint.textContent = "Log a few more pees and poos to see typical timings.";
    }
  }

  function renderLasts(events) {
    const setLast = (id, type) => {
      const ev = lastEventOfType(events, type);
      document.getElementById(id).textContent = ev
        ? `${formatTime(ev.at)} (${formatRelative(ev.at)})`
        : "—";
    };
    setLast("last-pee", "pee");
    setLast("last-poo", "poo");
    setLast("last-eat", "eat");

    const sortedSleep = events
      .filter(e => e.type === "sleep-start" || e.type === "sleep-end")
      .sort((a, b) => b.at - a.at);
    const lastSleep = sortedSleep[0];
    document.getElementById("last-sleep").textContent = lastSleep
      ? `${EVENT_LABELS[lastSleep.type]} at ${formatTime(lastSleep.at)} (${formatRelative(lastSleep.at)})`
      : "—";

    const row = document.getElementById("currently-row");
    const currently = document.getElementById("currently");
    if (isCurrentlyAsleep(events)) {
      row.hidden = false;
      currently.textContent = "😴 Asleep";
    } else {
      row.hidden = true;
    }
  }

  // Tracks the latest sleep transition so the 1-second tick can update the
  // counter without re-deriving from the event log.
  let bigClockState = null; // "asleep" | "awake" | null
  let bigClockSince = 0;

  function renderBigClock(events) {
    const card  = document.getElementById("big-clock");
    const label = document.getElementById("bc-label");
    const time  = document.getElementById("bc-time");
    const since = document.getElementById("bc-since");
    const { state, since: ts } = currentSleepState(events);
    bigClockState = state;
    bigClockSince = ts;
    if (!state) {
      card.hidden = true;
      return;
    }
    card.hidden = false;
    card.classList.toggle("asleep", state === "asleep");
    card.classList.toggle("awake",  state === "awake");
    label.textContent = state === "asleep" ? "Asleep for" : "Awake for";
    time.textContent  = formatCounter(Date.now() - ts);
    since.textContent = `since ${formatTime(ts)}`;
  }

  function tickBigClock() {
    if (!bigClockState) return;
    const time = document.getElementById("bc-time");
    if (time) time.textContent = formatCounter(Date.now() - bigClockSince);
  }

  function renderWindowList(listId, emptyId, windows, ongoingLabel, extraClass) {
    const list  = document.getElementById(listId);
    const empty = document.getElementById(emptyId);
    list.innerHTML = "";
    if (windows.length === 0) {
      empty.hidden = false;
      return;
    }
    empty.hidden = true;
    for (const w of windows) {
      const li = document.createElement("li");
      li.className = `ww ${extraClass}` + (w.ongoing ? " ongoing" : "");
      const range = document.createElement("span");
      range.className = "ww-range";
      range.textContent = w.ongoing
        ? `from ${formatTime(w.start)}`
        : `${formatTime(w.start)} – ${formatTime(w.end)}`;
      const dur = document.createElement("span");
      dur.className = "ww-dur";
      dur.textContent = formatDuration(w.end - w.start);
      li.appendChild(range);
      li.appendChild(dur);
      if (w.ongoing) {
        const tag = document.createElement("span");
        tag.className = "ww-tag";
        tag.textContent = ongoingLabel;
        li.appendChild(tag);
      }
      list.appendChild(li);
    }
  }

  function renderSleepWindows(events) {
    renderWindowList(
      "sleep-list", "sleep-empty",
      sleepWindowsForDay(events, selectedDay()),
      "Asleep", "sleep-ww",
    );
  }

  function renderWakeWindows(events) {
    renderWindowList(
      "wake-list", "wake-empty",
      wakeWindowsForDay(events, selectedDay()),
      "Awake", "wake-ww",
    );
  }

  function renderHistory(events) {
    const dayEvents = eventsForDay(events, selectedDay()).reverse();
    eventList.innerHTML = "";
    if (dayEvents.length === 0) {
      emptyState.hidden = false;
      return;
    }
    emptyState.hidden = true;
    for (const ev of dayEvents) {
      const li = document.createElement("li");
      li.className = "event";
      li.dataset.type = ev.type;
      li.dataset.id = ev.id;
      li.innerHTML = `
        <span class="dot"></span>
        <span class="time">${formatTime(ev.at)}</span>
        <span class="label">${EVENT_LABELS[ev.type] || ev.type}</span>
        <span class="note"></span>
      `;
      const noteEl = li.querySelector(".note");
      if (ev.type === "weight" && Number.isFinite(ev.weight)) {
        noteEl.textContent = ev.note ? `${formatWeight(ev.weight)} · ${ev.note}` : formatWeight(ev.weight);
      } else {
        noteEl.textContent = ev.note || "";
      }
      li.addEventListener("click", () => openEditDialog(ev));

      if (ev.photoId) {
        const img = document.createElement("img");
        img.className = "thumb";
        img.alt = "photo";
        img.loading = "lazy";
        img.dataset.photoId = ev.photoId;
        img.addEventListener("click", (e) => {
          e.stopPropagation(); // don't open the edit dialog
          openLightbox(ev.photoId);
        });
        li.appendChild(img);
        photoSrc(ev.photoId).then(url => { if (url) img.src = url; });
      }

      eventList.appendChild(li);
    }
  }

  // ---------- lightbox ----------
  const lightbox      = document.getElementById("lightbox");
  const lightboxImg   = document.getElementById("lightbox-img");
  const lightboxClose = document.getElementById("lightbox-close");

  async function openLightbox(photoId) {
    const url = await photoSrc(photoId);
    if (!url) { alert("Photo not yet available (still uploading?)."); return; }
    lightboxImg.src = url;
    lightbox.showModal();
  }

  lightboxClose.addEventListener("click", () => lightbox.close());
  // Click on backdrop closes the lightbox too.
  lightbox.addEventListener("click", (e) => {
    if (e.target === lightbox) lightbox.close();
  });

  // ---------- weekly charts ----------
  function weeklyData(events) {
    const today = startOfDay(new Date());
    const now = Date.now();
    const days = [];
    for (let i = 6; i >= 0; i--) {
      const d = new Date(today);
      d.setDate(d.getDate() - i);
      const from = startOfDay(d).getTime();
      const to = (i === 0) ? now : endOfDay(d).getTime();
      const sleepMs = sleepMsInRange(events, from, to);
      const dayEvents = eventsForDay(events, d);
      days.push({
        date: d,
        ymd: ymd(d),
        sleepHours: sleepMs / 3_600_000,
        pees:  dayEvents.filter(e => e.type === "pee").length,
        poos:  dayEvents.filter(e => e.type === "poo").length,
        meals: dayEvents.filter(e => e.type === "eat").length,
      });
    }
    return days;
  }

  function dayLabel(date, isToday) {
    if (isToday) return "Today";
    return date.toLocaleDateString(undefined, { weekday: "short" });
  }

  // Pick a chart Y maximum and tick count so every tick label is a clean
  // whole number (avoids 0, 0, 1, 1, 2 from rounding fractional steps).
  function niceAxis(rawMax) {
    if (!(rawMax > 0)) return { yMax: 1, steps: 1 };
    if (rawMax <= 4) {
      const m = Math.ceil(rawMax);
      return { yMax: m, steps: m };
    }
    if (rawMax <= 10) {
      const m = Math.ceil(rawMax / 2) * 2;
      return { yMax: m, steps: m / 2 };
    }
    const m = Math.ceil(rawMax / 5) * 5;
    return { yMax: m, steps: 5 };
  }

  // Sleep-specific axis: always 2-hour granularity, capped at 24h/day,
  // for a more readable picture of typical 10–18 h puppy sleep.
  function niceAxisSleepHours(rawMax) {
    if (!(rawMax > 0)) return { yMax: 2, steps: 2 };
    const m = Math.min(24, Math.max(2, Math.ceil(rawMax / 2) * 2));
    return { yMax: m, steps: m / 2 };
  }

  function escapeText(s) {
    return String(s).replace(/[&<>"']/g, c => (
      { "&": "&amp;", "<": "&lt;", ">": "&gt;", '"': "&quot;", "'": "&#39;" }[c]
    ));
  }

  function setChartSVG(svg, parts) {
    svg.innerHTML = parts.join("");
    svg.querySelectorAll(".bar[data-day]").forEach(b => {
      b.addEventListener("click", () => {
        dayPicker.value = b.dataset.day;
        render();
        const hist = document.querySelector(".history");
        if (hist) hist.scrollIntoView({ behavior: "smooth", block: "start" });
      });
    });
  }

  function drawSleepChart(days) {
    const svg = document.getElementById("chart-sleep");
    const W = 320, H = 160;
    const ML = 26, MR = 6, MT = 10, MB = 26;
    const innerW = W - ML - MR;
    const innerH = H - MT - MB;

    const rawMax = Math.max(...days.map(d => d.sleepHours));
    const { yMax, steps: ySteps } = niceAxisSleepHours(rawMax);

    const gap = 6;
    const barW = (innerW - (days.length - 1) * gap) / days.length;

    const parts = [];
    for (let i = 0; i <= ySteps; i++) {
      const y = MT + innerH * (1 - i / ySteps);
      const v = Math.round(yMax * i / ySteps * 10) / 10;
      const vText = v % 1 === 0 ? v : v.toFixed(1);
      parts.push(`<line class="grid" x1="${ML}" y1="${y}" x2="${W - MR}" y2="${y}"/>`);
      parts.push(`<text x="${ML - 4}" y="${y + 3}" text-anchor="end">${vText}h</text>`);
    }

    days.forEach((d, i) => {
      const isToday = i === days.length - 1;
      const x = ML + i * (barW + gap);
      const h = (d.sleepHours / yMax) * innerH;
      const y = MT + innerH - h;
      const title = `${d.date.toLocaleDateString(undefined, { weekday: "long", month: "short", day: "numeric" })} — ${d.sleepHours.toFixed(1)}h`;
      parts.push(
        `<rect class="bar bar-sleep ${isToday ? "" : "bar-faded"}" data-day="${d.ymd}" ` +
        `x="${x}" y="${y}" width="${barW}" height="${Math.max(0, h)}" rx="3">` +
        `<title>${escapeText(title)}</title></rect>`
      );
      parts.push(
        `<text x="${x + barW / 2}" y="${H - MB + 14}" text-anchor="middle">` +
        `${escapeText(dayLabel(d.date, isToday))}</text>`
      );
    });

    setChartSVG(svg, parts);
  }

  function drawCountsChart(days) {
    const svg = document.getElementById("chart-counts");
    const W = 320, H = 180;
    const ML = 22, MR = 6, MT = 10, MB = 26;
    const innerW = W - ML - MR;
    const innerH = H - MT - MB;

    const rawMax = Math.max(...days.flatMap(d => [d.pees, d.poos, d.meals]));
    const { yMax, steps: ySteps } = niceAxis(rawMax);

    const groupGap = 6;
    const innerBarGap = 2;
    const groupW = (innerW - (days.length - 1) * groupGap) / days.length;
    const barW = (groupW - 2 * innerBarGap) / 3;

    const parts = [];
    for (let i = 0; i <= ySteps; i++) {
      const y = MT + innerH * (1 - i / ySteps);
      const v = Math.round(yMax * i / ySteps);
      parts.push(`<line class="grid" x1="${ML}" y1="${y}" x2="${W - MR}" y2="${y}"/>`);
      parts.push(`<text x="${ML - 4}" y="${y + 3}" text-anchor="end">${v}</text>`);
    }

    const series = [
      { key: "pees",  label: "Pees",  cls: "bar-pee" },
      { key: "poos",  label: "Poos",  cls: "bar-poo" },
      { key: "meals", label: "Meals", cls: "bar-eat" },
    ];

    days.forEach((d, i) => {
      const isToday = i === days.length - 1;
      const groupX = ML + i * (groupW + groupGap);

      series.forEach((s, j) => {
        const val = d[s.key];
        const x = groupX + j * (barW + innerBarGap);
        const h = (val / yMax) * innerH;
        const y = MT + innerH - h;
        const title = `${d.date.toLocaleDateString(undefined, { weekday: "long", month: "short", day: "numeric" })} — ${s.label}: ${val}`;
        parts.push(
          `<rect class="bar ${s.cls} ${isToday ? "" : "bar-faded"}" data-day="${d.ymd}" ` +
          `x="${x}" y="${y}" width="${barW}" height="${Math.max(0, h)}" rx="2">` +
          `<title>${escapeText(title)}</title></rect>`
        );
      });

      parts.push(
        `<text x="${groupX + groupW / 2}" y="${H - MB + 14}" text-anchor="middle">` +
        `${escapeText(dayLabel(d.date, isToday))}</text>`
      );
    });

    setChartSVG(svg, parts);
  }

  function renderWeekly(events) {
    const days = weeklyData(events);
    drawSleepChart(days);
    drawCountsChart(days);
  }

  // ---------- weight ----------
  // Pick a "nice" kg axis that frames the data with a little headroom rather
  // than forcing 0-based (a puppy going 5→8 kg would otherwise look flat).
  function niceWeightAxis(min, max) {
    if (!(max > 0)) return { lo: 0, hi: 1, steps: 1 };
    if (min === max) { min = Math.max(0, min - 0.5); max = max + 0.5; }
    const span = max - min;
    let lo = Math.max(0, min - span * 0.15);
    let hi = max + span * 0.15;
    const rawStep = (hi - lo) / 4;
    const mag  = Math.pow(10, Math.floor(Math.log10(rawStep)));
    const norm = rawStep / mag;
    const step = (norm <= 1 ? 1 : norm <= 2 ? 2 : norm <= 2.5 ? 2.5 : norm <= 5 ? 5 : 10) * mag;
    lo = Math.floor(lo / step) * step;
    hi = Math.ceil(hi / step) * step;
    return { lo, hi, steps: Math.max(1, Math.round((hi - lo) / step)) };
  }

  // Human-readable detail for one weigh-in: date, weight, and the puppy's age
  // at that date (omitted if no birthday is configured).
  function weightPointInfo(w, birthday) {
    const dateStr = new Date(w.at).toLocaleDateString(undefined, { weekday: "short", month: "short", day: "numeric" });
    const age = formatAge(birthday, w.at);
    return `${dateStr} — ${formatWeight(w.weight)}${age ? ` · ${age}` : ""}`;
  }

  function drawWeightChart(weights, birthday) {
    const svg  = document.getElementById("chart-weight");
    const info = document.getElementById("weight-point-info");
    const W = 320, H = 180;
    const ML = 30, MR = 8, MT = 10, MB = 24;
    const innerW = W - ML - MR;
    const innerH = H - MT - MB;

    if (weights.length === 0) { svg.innerHTML = ""; info.textContent = ""; return; }

    const vals = weights.map(w => w.weight);
    const { lo, hi, steps } = niceWeightAxis(Math.min(...vals), Math.max(...vals));

    const t0 = weights[0].at;
    const t1 = weights[weights.length - 1].at;
    const tSpan = t1 - t0;
    const xOf = (t) => tSpan > 0 ? ML + ((t - t0) / tSpan) * innerW : ML + innerW / 2;
    const yOf = (v) => MT + innerH * (1 - (v - lo) / (hi - lo));

    const parts = [];
    for (let i = 0; i <= steps; i++) {
      const v = lo + (hi - lo) * i / steps;
      const y = yOf(v);
      parts.push(`<line class="grid" x1="${ML}" y1="${y}" x2="${W - MR}" y2="${y}"/>`);
      parts.push(`<text x="${ML - 4}" y="${y + 3}" text-anchor="end">${Math.round(v * 10) / 10}</text>`);
    }

    if (weights.length > 1) {
      const d = weights
        .map((w, i) => `${i === 0 ? "M" : "L"}${xOf(w.at).toFixed(1)} ${yOf(w.weight).toFixed(1)}`)
        .join(" ");
      parts.push(`<path class="weight-line" d="${d}"/>`);
    }

    // Visible dots, then larger transparent hit targets on top (easier to tap
    // on touch, and they carry the tooltip + click detail).
    weights.forEach(w => {
      parts.push(`<circle class="weight-dot" cx="${xOf(w.at).toFixed(1)}" cy="${yOf(w.weight).toFixed(1)}" r="3.5"/>`);
    });
    weights.forEach((w, i) => {
      const detail = weightPointInfo(w, birthday);
      parts.push(
        `<circle class="weight-hit" data-i="${i}" cx="${xOf(w.at).toFixed(1)}" cy="${yOf(w.weight).toFixed(1)}" r="10">` +
        `<title>${escapeText(detail)}</title></circle>`
      );
    });

    const fmtX = (t) => new Date(t).toLocaleDateString(undefined, { month: "short", day: "numeric" });
    parts.push(`<text x="${ML}" y="${H - MB + 16}" text-anchor="start">${escapeText(fmtX(t0))}</text>`);
    if (tSpan > 0) {
      parts.push(`<text x="${W - MR}" y="${H - MB + 16}" text-anchor="end">${escapeText(fmtX(t1))}</text>`);
    }

    svg.innerHTML = parts.join("");

    // Default the caption to the most recent weigh-in; hover/tap focuses a point.
    const hits = svg.querySelectorAll(".weight-hit");
    const focus = (i) => {
      info.textContent = weightPointInfo(weights[i], birthday);
      hits.forEach(h => h.classList.toggle("active", Number(h.dataset.i) === i));
    };
    hits.forEach(h => {
      const i = Number(h.dataset.i);
      h.addEventListener("mouseenter", () => focus(i));
      h.addEventListener("click", () => focus(i));
    });
    info.textContent = weightPointInfo(weights[weights.length - 1], birthday);
  }

  function renderWeight(events) {
    const weights = events
      .filter(e => e.type === "weight" && Number.isFinite(e.weight))
      .sort((a, b) => a.at - b.at);

    const empty    = document.getElementById("weight-empty");
    const latestEl = document.getElementById("weight-latest");
    const changeEl = document.getElementById("weight-change");
    const list     = document.getElementById("weight-list");

    const birthday = loadConfig().birthday;

    list.innerHTML = "";
    changeEl.classList.remove("up", "down");

    if (weights.length === 0) {
      empty.hidden = false;
      latestEl.textContent = "—";
      changeEl.textContent = "—";
      drawWeightChart([], birthday);
      return;
    }
    empty.hidden = true;

    const latest = weights[weights.length - 1];
    latestEl.textContent = formatWeight(latest.weight);

    if (weights.length >= 2) {
      const d = latest.weight - weights[weights.length - 2].weight;
      const rounded = Math.round(d * 100) / 100;
      const arrow = d > 0 ? "▲" : d < 0 ? "▼" : "▬";
      changeEl.textContent = `${arrow} ${d > 0 ? "+" : ""}${rounded} kg`;
      changeEl.classList.toggle("up", d > 0);
      changeEl.classList.toggle("down", d < 0);
    } else {
      changeEl.textContent = "—";
    }

    // Most-recent-first log; tap a row to edit that weigh-in.
    for (const w of [...weights].reverse()) {
      const li = document.createElement("li");
      li.className = "ww weight-ww";
      const date = document.createElement("span");
      date.className = "ww-range";
      const age = formatAge(birthday, w.at);
      const dateStr = new Date(w.at).toLocaleDateString(undefined, { month: "short", day: "numeric" });
      date.textContent = age ? `${dateStr} · ${age}` : dateStr;
      const val = document.createElement("span");
      val.className = "ww-dur";
      val.textContent = formatWeight(w.weight);
      li.appendChild(date);
      li.appendChild(val);
      li.addEventListener("click", () => openEditDialog(w));
      list.appendChild(li);
    }

    drawWeightChart(weights, birthday);
  }

  function renderDayBar() {
    const day = selectedDay();
    const isToday = ymd(day) === ymd(new Date());
    document.getElementById("day-next").disabled  = isToday;
    document.getElementById("day-today").disabled = isToday;
    const title = document.getElementById("overview-title");
    if (title) {
      title.textContent = isToday
        ? "Today's overview"
        : day.toLocaleDateString(undefined, { weekday: "long", month: "short", day: "numeric" });
    }
  }

  function renderHeader() {
    const cfg   = loadConfig();
    const title = document.getElementById("app-title");
    const ageEl = document.getElementById("puppy-age");
    title.textContent = cfg.name ? `🐶 ${cfg.name}` : "🐶 Puppy Tracker";
    document.title = cfg.name ? `${cfg.name} · Puppy Tracker` : "Puppy Tracker";
    const ageText = formatAge(cfg.birthday);
    ageEl.textContent = ageText;
    ageEl.hidden = !ageText;
  }

  function render() {
    const events = live();
    renderHeader();
    renderDayBar();
    renderBigClock(events);
    renderStats(events);
    renderLasts(events);
    renderTiming(events);
    renderSleepWindows(events);
    renderWakeWindows(events);
    renderWeekly(events);
    renderWeight(events);
    renderHistory(events);
  }

  // ---------- sync ----------
  let syncTimer  = null;
  let syncing    = false;
  let lastError  = null;
  let lastSynced = 0;

  function setStatus(state) {
    statusEl.classList.remove("offline", "syncing", "error", "pending");
    if (!navigator.onLine) {
      statusEl.textContent = "offline";
      statusEl.classList.add("offline");
      return;
    }
    switch (state) {
      case "syncing":
        statusEl.textContent = "syncing…";
        statusEl.classList.add("syncing");
        break;
      case "error":
        statusEl.textContent = "sync error";
        statusEl.classList.add("error");
        statusEl.title = lastError || "";
        break;
      case "pending":
        statusEl.textContent = "pending";
        statusEl.classList.add("pending");
        break;
      default:
        statusEl.textContent = lastSynced
          ? `synced ${formatRelative(lastSynced)}`
          : "synced";
        statusEl.title = "";
    }
  }

  function scheduleSync() {
    if (!navigator.onLine) { setStatus("pending"); return; }
    setStatus("pending");
    clearTimeout(syncTimer);
    syncTimer = setTimeout(sync, SYNC_DEBOUNCE_MS);
  }

  // Merge server response back into local storage. Anything local with a newer
  // updatedAt than the server's copy wins — that covers events the user added
  // during the in-flight sync request.
  function mergeServer(serverEvents) {
    const localById = new Map(loadAll().map(e => [e.id, e]));
    const merged = new Map();
    for (const se of serverEvents) {
      if (se && se.id) merged.set(se.id, se);
    }
    for (const [id, le] of localById) {
      const se = merged.get(id);
      if (!se || (le.updatedAt || 0) > (se.updatedAt || 0)) {
        merged.set(id, le);
      }
    }
    saveAll([...merged.values()]);
  }

  async function sync() {
    if (!currentUser) return;
    if (syncing) return;
    if (!navigator.onLine) { setStatus("pending"); return; }
    syncing = true;
    setStatus("syncing");
    try {
      // Push queued photos first so events that reference them won't return
      // 404s when other clients try to fetch.
      await syncPhotos();

      const res = await fetch(SYNC_URL, {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ events: loadAll() }),
      });
      if (res.status === 401) { handleLoggedOut(); return; }
      if (!res.ok) throw new Error(`HTTP ${res.status}`);
      const body = await res.json();
      if (Array.isArray(body.events)) {
        mergeServer(body.events);
        lastSynced = Date.now();
        lastError = null;
        render();
      }
      setStatus("synced");
    } catch (err) {
      lastError = err.message || String(err);
      console.warn("sync failed:", lastError);
      setStatus("error");
    } finally {
      syncing = false;
    }
  }

  // ---------- config sync ----------
  // Reconcile the local config cache with the host. Whichever side has the
  // newer updatedAt wins: adopt the server's copy, or push ours if it's ahead
  // (e.g. edited on this device while another client hadn't changed it). This
  // self-heals a failed push — the local copy stays newer and re-pushes next tick.
  async function syncConfig() {
    if (!currentUser) return;
    if (!navigator.onLine) return;
    const local = loadConfig();
    try {
      const res = await fetch("api/config");
      if (res.status === 401) { handleLoggedOut(); return; }
      if (!res.ok) throw new Error(`HTTP ${res.status}`);
      const body = await res.json();
      const server = {
        name: body.name || "",
        birthday: body.birthday || "",
        updatedAt: Number.isFinite(body.updatedAt) ? body.updatedAt : 0,
      };
      if (server.updatedAt > local.updatedAt) {
        saveConfig(server);
        renderHeader();
      } else if (local.updatedAt > server.updatedAt) {
        await pushConfig(local);
      }
    } catch (err) {
      console.warn("config sync failed:", err);
    }
  }

  async function pushConfig(cfg) {
    if (!navigator.onLine) return;
    const res = await fetch("api/config", {
      method: "PUT",
      headers: { "Content-Type": "application/json" },
      body: JSON.stringify(cfg),
    });
    if (!res.ok) throw new Error(`HTTP ${res.status}`);
    const body = await res.json();
    // Adopt the server's answer if it turned out to be newer (another client won).
    if (Number.isFinite(body.updatedAt) && body.updatedAt > cfg.updatedAt) {
      saveConfig({ name: body.name || "", birthday: body.birthday || "", updatedAt: body.updatedAt });
      renderHeader();
    }
  }

  // ---------- dialogs ----------
  const noteDialog       = document.getElementById("note-dialog");
  const noteForm         = document.getElementById("note-form");
  const noteInput        = document.getElementById("note-input");
  const noteDate         = document.getElementById("note-date");
  const noteTime         = document.getElementById("note-time");
  const noteTitle        = document.getElementById("note-title");
  const notePhotoInput   = document.getElementById("note-photo-input");
  const notePhotoBtn     = document.getElementById("note-photo-btn");
  const notePhotoClear   = document.getElementById("note-photo-clear");
  const notePhotoPreview = document.getElementById("note-photo-preview");
  const noteWeightField  = document.getElementById("note-weight-field");
  const noteWeight       = document.getElementById("note-weight");
  let pendingType        = null;
  let notePhotoBlob      = null; // pending blob for the dialog (not yet committed)
  let notePhotoURL       = null; // current preview object URL

  function clearNotePhoto() {
    notePhotoBlob = null;
    if (notePhotoURL) { URL.revokeObjectURL(notePhotoURL); notePhotoURL = null; }
    notePhotoPreview.hidden = true;
    notePhotoPreview.innerHTML = "";
    notePhotoClear.hidden = true;
    notePhotoBtn.textContent = "📷 Add photo";
    notePhotoInput.value = "";
  }

  function openNoteDialog(type) {
    pendingType = type;
    noteInput.value = "";
    const now = Date.now();
    noteDate.value = toDateInput(now);
    noteTime.value = toTimeInput(now);
    noteTitle.textContent = `Log ${EVENT_LABELS[type]}`;
    const isWeight = type === "weight";
    noteWeightField.hidden = !isWeight;
    noteWeight.value = "";
    clearNotePhoto();
    noteDialog.showModal();
    setTimeout(() => (isWeight ? noteWeight : noteInput).focus(), 50);
  }

  function noteDialogAt() {
    const parsed = fromDateTimeInputs(noteDate.value, noteTime.value);
    return Number.isFinite(parsed) ? parsed : Date.now();
  }

  document.getElementById("note-time-now").addEventListener("click", () => {
    const now = Date.now();
    noteDate.value = toDateInput(now);
    noteTime.value = toTimeInput(now);
  });

  notePhotoBtn.addEventListener("click", () => notePhotoInput.click());
  notePhotoClear.addEventListener("click", () => clearNotePhoto());
  notePhotoInput.addEventListener("change", async (e) => {
    const file = e.target.files?.[0];
    if (!file) return;
    try {
      notePhotoBlob = await resizeImage(file);
      if (notePhotoURL) URL.revokeObjectURL(notePhotoURL);
      notePhotoURL = URL.createObjectURL(notePhotoBlob);
      notePhotoPreview.innerHTML = `<img alt="" src="${notePhotoURL}">`;
      notePhotoPreview.hidden = false;
      notePhotoClear.hidden = false;
      notePhotoBtn.textContent = "📷 Replace photo";
    } catch (err) {
      alert("Couldn't process that photo: " + err.message);
    }
  });

  document.getElementById("note-save").addEventListener("click", async (e) => {
    e.preventDefault();
    if (!pendingType) { noteDialog.close(); return; }
    let weight;
    if (pendingType === "weight") {
      weight = parseFloat(noteWeight.value);
      if (!(weight > 0)) { alert("Enter a weight in kilograms."); return; }
      weight = Math.round(weight * 100) / 100;
    }
    let photoId = "";
    if (notePhotoBlob) {
      photoId = uuid();
      try { await putPhoto(photoId, notePhotoBlob, false); }
      catch (err) {
        alert("Couldn't store photo locally: " + err.message);
        return;
      }
    }
    addEvent(pendingType, noteInput.value.trim(), noteDialogAt(), photoId, weight);
    pendingType = null;
    clearNotePhoto();
    noteDialog.close();
  });
  noteForm.querySelector('button[value="cancel"]').addEventListener("click", (e) => {
    e.preventDefault();
    pendingType = null;
    clearNotePhoto();
    noteDialog.close();
  });

  // Edit dialog
  const editDialog       = document.getElementById("edit-dialog");
  const editForm         = document.getElementById("edit-form");
  const editDate         = document.getElementById("edit-date");
  const editTime         = document.getElementById("edit-time");
  const editNote         = document.getElementById("edit-note");
  const editDelete       = document.getElementById("edit-delete");
  const editPhotoInput   = document.getElementById("edit-photo-input");
  const editPhotoBtn     = document.getElementById("edit-photo-btn");
  const editPhotoClear   = document.getElementById("edit-photo-clear");
  const editPhotoPreview = document.getElementById("edit-photo-preview");
  const editWeightField  = document.getElementById("edit-weight-field");
  const editWeight       = document.getElementById("edit-weight");
  let editingId          = null;
  let editPhotoId        = "";      // current photoId for this event
  let editPhotoBlob      = null;    // new blob chosen in this session
  let editPhotoURL       = null;
  let editPhotoCleared   = false;   // user removed an existing photo

  function setEditPreviewFromURL(url) {
    if (!url) { editPhotoPreview.hidden = true; editPhotoPreview.innerHTML = ""; return; }
    editPhotoPreview.innerHTML = `<img alt="" src="${url}">`;
    editPhotoPreview.hidden = false;
  }

  function clearEditPhotoLocalState() {
    editPhotoBlob = null;
    if (editPhotoURL) { URL.revokeObjectURL(editPhotoURL); editPhotoURL = null; }
    editPhotoInput.value = "";
  }

  async function openEditDialog(ev) {
    editingId = ev.id;
    editDate.value = toDateInput(ev.at);
    editTime.value = toTimeInput(ev.at);
    editNote.value = ev.note || "";
    editWeightField.hidden = ev.type !== "weight";
    editWeight.value = (ev.type === "weight" && Number.isFinite(ev.weight)) ? ev.weight : "";
    editPhotoId = ev.photoId || "";
    editPhotoCleared = false;
    clearEditPhotoLocalState();
    if (editPhotoId) {
      const url = await photoSrc(editPhotoId);
      setEditPreviewFromURL(url);
      editPhotoBtn.textContent = "📷 Replace photo";
      editPhotoClear.hidden = false;
    } else {
      setEditPreviewFromURL(null);
      editPhotoBtn.textContent = "📷 Add photo";
      editPhotoClear.hidden = true;
    }
    editDialog.showModal();
  }

  editPhotoBtn.addEventListener("click", () => editPhotoInput.click());
  editPhotoClear.addEventListener("click", () => {
    editPhotoCleared = true;
    clearEditPhotoLocalState();
    setEditPreviewFromURL(null);
    editPhotoBtn.textContent = "📷 Add photo";
    editPhotoClear.hidden = true;
  });
  editPhotoInput.addEventListener("change", async (e) => {
    const file = e.target.files?.[0];
    if (!file) return;
    try {
      editPhotoBlob = await resizeImage(file);
      if (editPhotoURL) URL.revokeObjectURL(editPhotoURL);
      editPhotoURL = URL.createObjectURL(editPhotoBlob);
      setEditPreviewFromURL(editPhotoURL);
      editPhotoCleared = true; // a new photo supersedes any existing one
      editPhotoBtn.textContent = "📷 Replace photo";
      editPhotoClear.hidden = false;
    } catch (err) {
      alert("Couldn't process that photo: " + err.message);
    }
  });

  editForm.querySelector('button[value="save"]').addEventListener("click", async (e) => {
    e.preventDefault();
    if (!editingId) { editDialog.close(); return; }
    const newAt = fromDateTimeInputs(editDate.value, editTime.value);
    const patch = {
      at: Number.isFinite(newAt) ? newAt : undefined,
      note: editNote.value.trim(),
    };
    if (!editWeightField.hidden) {
      const kg = parseFloat(editWeight.value);
      if (!(kg > 0)) { alert("Enter a weight in kilograms."); return; }
      patch.weight = Math.round(kg * 100) / 100;
    }
    if (editPhotoBlob) {
      const newId = uuid();
      try { await putPhoto(newId, editPhotoBlob, false); }
      catch (err) { alert("Couldn't store photo locally: " + err.message); return; }
      patch.photoId = newId;
    } else if (editPhotoCleared) {
      patch.photoId = "";
    }
    updateEvent(editingId, patch);
    editingId = null;
    clearEditPhotoLocalState();
    editDialog.close();
  });

  editForm.querySelector('button[value="cancel"]').addEventListener("click", (e) => {
    e.preventDefault();
    editingId = null;
    clearEditPhotoLocalState();
    editDialog.close();
  });

  editDelete.addEventListener("click", (e) => {
    e.preventDefault();
    if (editingId && confirm("Delete this event?")) {
      deleteEvent(editingId);
    }
    editingId = null;
    clearEditPhotoLocalState();
    editDialog.close();
  });

  // Settings dialog (puppy name + birthday)
  // ---------- theme ----------
  // Preference is device-global (not per user). No stored choice → follow the
  // OS via the prefers-color-scheme media query; a choice sets data-theme on
  // <html>, which the CSS treats as an override. The <head> applies any saved
  // choice before first paint; this just resolves state and reacts to the toggle.
  const THEME_KEY = "puppy-tracker:theme";
  const prefersDark = () =>
    window.matchMedia && window.matchMedia("(prefers-color-scheme: dark)").matches;
  function effectiveTheme() {
    const s = localStorage.getItem(THEME_KEY);
    return s === "light" || s === "dark" ? s : (prefersDark() ? "dark" : "light");
  }
  function setTheme(theme) {
    document.documentElement.dataset.theme = theme;
    try { localStorage.setItem(THEME_KEY, theme); } catch { /* ignore */ }
  }

  const settingsDialog   = document.getElementById("settings-dialog");
  const settingsForm     = document.getElementById("settings-form");
  const settingsName     = document.getElementById("settings-name");
  const settingsBirthday = document.getElementById("settings-birthday");
  const settingsTheme    = document.getElementById("settings-theme");

  // Apply live so the toggle previews immediately (independent of Save/Cancel).
  settingsTheme.addEventListener("change", () => {
    setTheme(settingsTheme.checked ? "dark" : "light");
  });

  function openSettingsDialog() {
    const cfg = loadConfig();
    settingsName.value     = cfg.name;
    settingsBirthday.value = cfg.birthday;
    settingsTheme.checked  = effectiveTheme() === "dark";
    settingsDialog.showModal();
    setTimeout(() => settingsName.focus(), 50);
  }

  document.getElementById("settings-btn").addEventListener("click", openSettingsDialog);

  settingsForm.querySelector('button[value="save"]').addEventListener("click", async (e) => {
    e.preventDefault();
    const cfg = {
      name: settingsName.value.trim(),
      birthday: settingsBirthday.value,
      updatedAt: Date.now(),
    };
    saveConfig(cfg);       // cache locally for instant + offline paint
    renderHeader();
    settingsDialog.close();
    try {
      await pushConfig(cfg);
    } catch (err) {
      console.warn("config save failed:", err);
      // Kept locally; syncConfig retries automatically once the host is reachable.
    }
  });
  settingsForm.querySelector('button[value="cancel"]').addEventListener("click", (e) => {
    e.preventDefault();
    settingsDialog.close();
  });

  // ---------- delete account ----------
  const deleteAccountDialog   = document.getElementById("delete-account-dialog");
  const deleteAccountPassword = document.getElementById("delete-account-password");
  const deleteAccountError    = document.getElementById("delete-account-error");
  const deleteAccountConfirm  = document.getElementById("delete-account-confirm");

  document.getElementById("delete-account-btn").addEventListener("click", () => {
    settingsDialog.close();
    deleteAccountPassword.value = "";
    deleteAccountError.hidden = true;
    deleteAccountDialog.showModal();
    setTimeout(() => deleteAccountPassword.focus(), 50);
  });

  deleteAccountConfirm.addEventListener("click", async () => {
    deleteAccountError.hidden = true;
    deleteAccountConfirm.disabled = true;
    try {
      const res = await fetch("api/me", {
        method: "DELETE",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ password: deleteAccountPassword.value }),
      });
      if (!res.ok) {
        const msg = (await res.text()).trim();
        throw new Error(res.status === 401 ? "Incorrect password" : (msg || `HTTP ${res.status}`));
      }
      // Account is gone server-side. Wipe this user's local cache before the
      // reload drops us back on the login screen.
      try {
        localStorage.removeItem(eventsKey());
        localStorage.removeItem(configKey());
      } catch { /* ignore */ }
      clearUser();
      deleteAccountDialog.close();
      location.reload();
    } catch (err) {
      deleteAccountError.textContent = err.message || "Something went wrong";
      deleteAccountError.hidden = false;
    } finally {
      deleteAccountConfirm.disabled = false;
    }
  });

  // ---------- wiring ----------
  document.querySelectorAll("button.action").forEach(btn => {
    btn.addEventListener("click", () => openNoteDialog(btn.dataset.type));
  });

  dayPicker.value = ymd(new Date());
  dayPicker.addEventListener("change", render);

  function shiftSelectedDay(days) {
    const d = selectedDay();
    d.setDate(d.getDate() + days);
    dayPicker.value = ymd(d);
    render();
  }
  document.getElementById("day-prev").addEventListener("click", () => shiftSelectedDay(-1));
  document.getElementById("day-next").addEventListener("click", () => shiftSelectedDay(+1));
  document.getElementById("day-today").addEventListener("click", () => {
    dayPicker.value = ymd(new Date());
    render();
  });

  // Clicking the status pill forces an immediate sync.
  statusEl.style.cursor = "pointer";
  statusEl.title = "Click to sync now";
  statusEl.addEventListener("click", () => { clearTimeout(syncTimer); sync(); });

  window.addEventListener("online", () => { setStatus(); sync(); syncConfig(); });
  window.addEventListener("offline", () => setStatus());

  // Service worker (independent of auth). The worker no longer auto-activates a
  // new build; instead we detect the waiting worker and let the user choose when
  // to swap onto fresh assets, so a long-open tab isn't left running stale JS.
  if ("serviceWorker" in navigator) {
    const updateBanner = document.getElementById("update-banner");
    const updateReload = document.getElementById("update-reload");
    const updateLater  = document.getElementById("update-later");
    let waitingWorker  = null;

    // Whether there was already a controlling worker when the page loaded. On a
    // brand-new install there isn't, and clients.claim() fires an initial
    // controllerchange we must NOT reload on (there's nothing to refresh to).
    const hadController = !!navigator.serviceWorker.controller;
    let reloadRequested = false; // user pressed Reload → controllerchange reloads
    let refreshing      = false; // guard against a reload loop

    navigator.serviceWorker.addEventListener("controllerchange", () => {
      if (refreshing) return;
      if (!hadController && !reloadRequested) return; // first-install claim
      refreshing = true;
      location.reload();
    });

    function showUpdateBanner(worker) {
      waitingWorker = worker;
      updateBanner.hidden = false;
    }

    updateReload.addEventListener("click", () => {
      reloadRequested = true;
      updateBanner.hidden = true;
      // Tell the waiting worker to activate; controllerchange then reloads us.
      if (waitingWorker) waitingWorker.postMessage({ type: "SKIP_WAITING" });
    });
    // "Later" just dismisses; the next update (or reload) surfaces it again.
    updateLater.addEventListener("click", () => { updateBanner.hidden = true; });

    // Only prompt when a *previous* worker was already in control — that check
    // is what suppresses the banner on the very first install.
    function trackInstalling(worker) {
      worker.addEventListener("statechange", () => {
        if (worker.state === "installed" && navigator.serviceWorker.controller) {
          showUpdateBanner(worker);
        }
      });
    }

    function watchForUpdate(reg) {
      // A worker may already be waiting from a previous session's update.
      if (reg.waiting && navigator.serviceWorker.controller) showUpdateBanner(reg.waiting);
      reg.addEventListener("updatefound", () => {
        if (reg.installing) trackInstalling(reg.installing);
      });
      // Browsers only auto-check for a new worker on navigation, so also poll
      // hourly and whenever the tab becomes visible again.
      setInterval(() => reg.update().catch(() => {}), 60 * 60 * 1000);
      document.addEventListener("visibilitychange", () => {
        if (document.visibilityState === "visible") reg.update().catch(() => {});
      });
    }

    window.addEventListener("load", () => {
      navigator.serviceWorker.register("sw.js")
        .then(watchForUpdate)
        .catch(err => console.error("SW", err));
    });
  }

  // ---------- auth gate ----------
  // The tracker only boots once we know who the user is. startApp() does the
  // first paint, initial sync, and starts the periodic timers — guarded so it
  // runs at most once per page load even if login and the session check race.
  const authScreen   = document.getElementById("auth-screen");
  const appEl        = document.getElementById("app");
  const authForm     = document.getElementById("auth-form");
  const authEmail    = document.getElementById("auth-email");
  const authPassword = document.getElementById("auth-password");
  const authInvite   = document.getElementById("auth-invite");
  const authInviteFld= document.getElementById("auth-invite-field");
  const authError    = document.getElementById("auth-error");
  const authSubmit   = document.getElementById("auth-submit");
  const authSub      = document.getElementById("auth-sub");
  const authToggleBtn= document.getElementById("auth-toggle-btn");
  const authToggleTxt= document.getElementById("auth-toggle-text");
  let authMode = "login"; // or "register"
  let appStarted = false;

  // Remember who was last signed in so an offline reload can still open the
  // app against the cached data instead of stranding the user on a login screen
  // it can't verify. Cleared only on an explicit logout or a server 401.
  const SESSION_KEY = "puppy-tracker:session:v1";
  function setUser(u) {
    currentUser = u;
    try { localStorage.setItem(SESSION_KEY, JSON.stringify(u)); } catch { /* ignore */ }
  }
  function clearUser() {
    currentUser = null;
    try { localStorage.removeItem(SESSION_KEY); } catch { /* ignore */ }
  }
  function cachedUser() {
    try {
      const u = JSON.parse(localStorage.getItem(SESSION_KEY));
      return u && u.id ? u : null;
    } catch { return null; }
  }

  function startApp() {
    if (appStarted) return;
    appStarted = true;

    // Live-update relative times and (eventually) sync status text.
    setInterval(() => {
      const evs = live();
      renderHeader();
      renderBigClock(evs);
      renderStats(evs);
      renderLasts(evs);
      renderTiming(evs);
      renderSleepWindows(evs);
      renderWakeWindows(evs);
      renderWeekly(evs);
      if (navigator.onLine && !syncing) setStatus();
    }, 60_000);

    setInterval(tickBigClock, 1000);
    setInterval(sync, SYNC_POLL_MS);
    setInterval(syncConfig, SYNC_POLL_MS);

    setStatus();
    render();
    sync();
    syncConfig();
  }

  function showAuth() {
    appEl.hidden = true;
    authScreen.hidden = false;
  }

  function showApp() {
    authScreen.hidden = true;
    appEl.hidden = false;
  }

  // Called when the server reports we're no longer authenticated (expired or
  // revoked session). Drop back to the login screen without wiping the local
  // cache — logging back in as the same user picks it straight back up.
  function handleLoggedOut() {
    clearUser();
    setStatus("offline");
    showAuth();
  }

  function renderAuthMode() {
    const reg = authMode === "register";
    authInviteFld.hidden = !reg;
    authInvite.required = reg;
    authSubmit.textContent = reg ? "Create account" : "Sign in";
    authSub.textContent = reg ? "Create your account" : "Sign in to continue";
    authToggleTxt.textContent = reg ? "Already have an account?" : "No account yet?";
    authToggleBtn.textContent = reg ? "Sign in" : "Create one";
    authPassword.autocomplete = reg ? "new-password" : "current-password";
    authError.hidden = true;
  }

  authToggleBtn.addEventListener("click", () => {
    authMode = authMode === "login" ? "register" : "login";
    renderAuthMode();
  });

  authForm.addEventListener("submit", async (e) => {
    e.preventDefault();
    authError.hidden = true;
    authSubmit.disabled = true;
    const body = { email: authEmail.value.trim(), password: authPassword.value };
    if (authMode === "register") body.invite = authInvite.value.trim();
    try {
      const res = await fetch(authMode === "register" ? "api/register" : "api/login", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify(body),
      });
      if (!res.ok) {
        const msg = (await res.text()).trim();
        throw new Error(msg || `HTTP ${res.status}`);
      }
      setUser(await res.json());
      authForm.reset();
      showApp();
      startApp();
    } catch (err) {
      authError.textContent = err.message || "Something went wrong";
      authError.hidden = false;
    } finally {
      authSubmit.disabled = false;
    }
  });

  document.getElementById("logout-btn").addEventListener("click", async () => {
    try { await fetch("api/logout", { method: "POST" }); } catch { /* ignore */ }
    clearUser();
    // Full reload is the simplest way to clear in-memory app state and timers.
    location.reload();
  });

  // On load, ask the server who we are. A valid session boots straight into the
  // app. A 401 means log in. A network failure (offline PWA) falls back to the
  // last cached session so offline data stays reachable — a later sync will
  // 401 and bounce to login if that session has actually gone stale.
  (async function bootstrap() {
    try {
      const res = await fetch("api/me");
      if (res.ok) {
        setUser(await res.json());
        showApp();
        startApp();
        return;
      }
      clearUser(); // explicit 401/403: session is gone
    } catch {
      const cached = cachedUser();
      if (cached) {
        currentUser = cached;
        showApp();
        startApp();
        return;
      }
    }
    renderAuthMode();
    showAuth();
  })();
})();