(() => {
  "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 exercisesKey = () => `puppy-tracker:${currentUser.id}:exercises: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",
    "training":    "Training",
  };

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

  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();
  }

  // ---------- exercises (training definitions) ----------
  // User-defined training exercises ("Sit", "Leash walking", …), each with
  // optional instruction text. They sync like events: UUID ids, last-write-wins
  // on updatedAt, tombstoned deletes — but as their own collection, since they
  // are definitions rather than things that happened at a point in time.
  function loadExercises() {
    try {
      const parsed = JSON.parse(localStorage.getItem(exercisesKey()));
      return Array.isArray(parsed) ? parsed : [];
    } catch {
      return [];
    }
  }

  function saveExercises(list) {
    localStorage.setItem(exercisesKey(), JSON.stringify(list));
  }

  function liveExercises() {
    return loadExercises()
      .filter(x => !x.deleted)
      .sort((a, b) => (a.name || "").localeCompare(b.name || ""));
  }

  function addExercise(name, note) {
    const list = loadExercises();
    list.push({ id: uuid(), name, note: note || "", updatedAt: Date.now() });
    saveExercises(list);
    scheduleSync();
    render();
  }

  function updateExercise(id, patch) {
    saveExercises(loadExercises().map(x =>
      x.id === id ? { ...x, ...patch, updatedAt: Date.now() } : x
    ));
    scheduleSync();
    render();
  }

  function deleteExercise(id) {
    // Tombstone, like events. Logged training sessions keep referencing the id;
    // name lookups still resolve through the tombstone (see exerciseNames).
    saveExercises(loadExercises().map(x =>
      x.id === id ? { ...x, deleted: true, updatedAt: Date.now() } : x
    ));
    scheduleSync();
    render();
  }

  // id -> name across *all* exercises, tombstones included, so history rows for
  // a deleted exercise still show its name instead of a generic "Training".
  function exerciseNames() {
    return new Map(loadExercises().map(x => [x.id, x.name]));
  }

  // ---------- 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;
  }

  // Current state derived from the *latest* sleep event. The single source of
  // truth for both the big clock and the "Currently" row. For two boundary
  // events sharing the same `at` (common once "now" events are minute-floored),
  // the one logged later (higher updatedAt) wins, so the tie resolves the same
  // way everywhere it's read.
  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 ||
          (e.at === latest.at && (e.updatedAt || 0) > (latest.updatedAt || 0))) {
        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");
    const gramsTotal = dayEvents
      .filter(e => e.type === "eat" && Number.isFinite(e.grams))
      .reduce((s, e) => s + e.grams, 0);
    const gramsEl = document.getElementById("stat-meals-grams");
    gramsEl.textContent = gramsTotal > 0 ? `${Math.round(gramsTotal)} g` : "";
    gramsEl.hidden = !(gramsTotal > 0);
    document.getElementById("stat-pees").textContent  = count("pee");
    document.getElementById("stat-poos").textContent  = count("poo");
    document.getElementById("stat-training").textContent = count("training");
  }

  // 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)})`
      : "—";
  }

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

      for (const pid of photoIdsOf(ev)) {
        const img = document.createElement("img");
        img.className = "thumb";
        img.alt = "photo";
        img.loading = "lazy";
        img.dataset.photoId = pid;
        img.addEventListener("click", (e) => {
          e.stopPropagation(); // don't open the edit dialog
          openLightbox(pid);
        });
        li.appendChild(img);
        photoSrc(pid).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,
        grams: dayEvents
          .filter(e => e.type === "eat" && Number.isFinite(e.grams))
          .reduce((s, e) => s + e.grams, 0),
      });
    }
    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):
  // 1-unit gridlines up to 10, 2-unit up to 20, 5-unit beyond.
  function niceAxis(rawMax) {
    if (!(rawMax > 0)) return { yMax: 1, steps: 1 };
    if (rawMax <= 10) {
      const m = Math.ceil(rawMax);
      return { yMax: m, steps: m };
    }
    if (rawMax <= 20) {
      const m = Math.ceil(rawMax / 2) * 2;
      return { yMax: m, steps: m / 2 };
    }
    const m = Math.ceil(rawMax / 5) * 5;
    return { yMax: m, steps: m / 5 };
  }

  // Grams axis: 0-based with a "nice" step so tick labels stay round whatever
  // the daily totals are (tens of grams for a tiny puppy, hundreds+ later).
  function niceAxisGrams(rawMax) {
    if (!(rawMax > 0)) return { yMax: 100, steps: 2 };
    const rawStep = rawMax / 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;
    const yMax = Math.ceil(rawMax / step) * step;
    return { yMax, steps: Math.max(1, Math.round(yMax / step)) };
  }

  // 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);
  }

  // Grams of food per day. Hidden entirely until any meal in the window has an
  // amount logged, so the weekly card doesn't grow an empty chart.
  function drawGramsChart(days) {
    const wrap = document.getElementById("grams-chart-wrap");
    const svg  = document.getElementById("chart-grams");
    if (!days.some(d => d.grams > 0)) { wrap.hidden = true; return; }
    wrap.hidden = false;

    const W = 320, H = 160;
    const ML = 34, MR = 6, MT = 10, MB = 26;
    const innerW = W - ML - MR;
    const innerH = H - MT - MB;

    const { yMax, steps: ySteps } = niceAxisGrams(Math.max(...days.map(d => d.grams)));

    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 = yMax * i / ySteps;
      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}</text>`);
    }

    days.forEach((d, i) => {
      const isToday = i === days.length - 1;
      const x = ML + i * (barW + gap);
      const h = (d.grams / yMax) * innerH;
      const y = MT + innerH - h;
      const title = `${d.date.toLocaleDateString(undefined, { weekday: "long", month: "short", day: "numeric" })} — ${Math.round(d.grams)} g`;
      parts.push(
        `<rect class="bar bar-eat ${isToday ? "" : "bar-faded"}" data-day="${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 renderWeekly(events) {
    const days = weeklyData(events);
    drawSleepChart(days);
    drawCountsChart(days);
    drawGramsChart(days);
  }

  // ---------- pattern charts (last 14 days) ----------
  const PATTERN_DAYS = 14;

  // Actogram: one row per day (oldest at top), a midnight-to-midnight track with
  // the puppy's sleep shaded. Sleep windows are clipped to each day, so a night
  // that crosses midnight shows correctly split across two rows. Today's open
  // sleep runs to now (sleepWindows already clips ongoing sleep to Date.now()).
  function renderSleepTimeline(events) {
    const svg = document.getElementById("chart-sleep-timeline");
    if (!svg) return;
    const N = PATTERN_DAYS;
    const W = 320, H = 228;
    const ML = 44, MR = 8, MT = 16, MB = 4;
    const innerW = W - ML - MR;
    const rowGap = 2;
    const rowH = (H - MT - MB - (N - 1) * rowGap) / N;
    const dayMs = 86_400_000;

    const today = startOfDay(new Date());
    const windows = sleepWindows(events);
    const xOf = (frac) => ML + frac * innerW;

    const parts = [];
    for (const hr of [0, 6, 12, 18, 24]) {
      const x = xOf(hr / 24);
      parts.push(`<line class="grid" x1="${x.toFixed(1)}" y1="${MT}" x2="${x.toFixed(1)}" y2="${H - MB}"/>`);
      const anchor = hr === 0 ? "start" : hr === 24 ? "end" : "middle";
      parts.push(`<text x="${x.toFixed(1)}" y="${MT - 5}" text-anchor="${anchor}">${hr}h</text>`);
    }

    for (let i = 0; i < N; i++) {
      const day = new Date(today);
      day.setDate(day.getDate() - (N - 1 - i)); // oldest at top, today at bottom
      const dayStart = startOfDay(day).getTime();
      const dayEnd = dayStart + dayMs;
      const isToday = ymd(day) === ymd(new Date());
      const y = MT + i * (rowH + rowGap);

      parts.push(`<rect class="stl-track" x="${ML}" y="${y.toFixed(1)}" width="${innerW}" height="${rowH.toFixed(1)}" rx="2"/>`);

      for (const wdw of windows) {
        const s = Math.max(wdw.start, dayStart);
        const e = Math.min(wdw.end, dayEnd);
        if (e <= s) continue;
        const x = xOf((s - dayStart) / dayMs);
        const wpx = ((e - s) / dayMs) * innerW;
        parts.push(`<rect class="stl-sleep" x="${x.toFixed(1)}" y="${y.toFixed(1)}" width="${Math.max(0.6, wpx).toFixed(1)}" height="${rowH.toFixed(1)}" rx="1.5"/>`);
      }

      const label = isToday ? "Today" : `${day.toLocaleDateString(undefined, { weekday: "short" })} ${day.getDate()}`;
      parts.push(`<text class="stl-day ${isToday ? "stl-today" : ""}" x="${ML - 6}" y="${(y + rowH / 2 + 3).toFixed(1)}" text-anchor="end">${escapeText(label)}</text>`);

      const title = day.toLocaleDateString(undefined, { weekday: "long", month: "short", day: "numeric" });
      parts.push(`<rect class="bar stl-hit" data-day="${ymd(day)}" x="${ML}" y="${y.toFixed(1)}" width="${innerW}" height="${rowH.toFixed(1)}"><title>${escapeText(title)}</title></rect>`);
    }

    setChartSVG(svg, parts); // wires the .bar[data-day] click → select that day
  }

  // Hour-of-day heatmap: one row per event type, 24 cells shaded by how often
  // that event lands in each hour across the window. Reveals daily rhythm that
  // the median gap can't show (e.g. "always poos ~7am and ~6pm").
  function renderHourHeatmap(events) {
    const svg = document.getElementById("chart-hour-heatmap");
    if (!svg) return;
    const from = startOfDay(new Date(Date.now() - (PATTERN_DAYS - 1) * 86_400_000)).getTime();

    const series = [
      { type: "pee", label: "Pees",  cls: "hm-pee" },
      { type: "poo", label: "Poos",  cls: "hm-poo" },
      { type: "eat", label: "Meals", cls: "hm-eat" },
    ];
    const counts = {};
    for (const s of series) counts[s.type] = new Array(24).fill(0);
    for (const e of events) {
      if (e.at < from) continue;
      if (counts[e.type]) counts[e.type][new Date(e.at).getHours()]++;
    }

    const W = 320, H = 120;
    const ML = 40, MR = 8, MT = 6, MB = 18;
    const innerW = W - ML - MR;
    const rowGap = 6;
    const rowH = (H - MT - MB - (series.length - 1) * rowGap) / series.length;
    const cellW = innerW / 24;

    const parts = [];
    series.forEach((s, r) => {
      const y = MT + r * (rowH + rowGap);
      const max = Math.max(1, ...counts[s.type]);
      for (let h = 0; h < 24; h++) {
        const c = counts[s.type][h];
        const op = c === 0 ? 0.06 : 0.2 + 0.8 * (c / max);
        const x = ML + h * cellW;
        const range = `${pad2(h)}:00–${pad2((h + 1) % 24)}:00`;
        parts.push(
          `<rect class="hm-cell ${s.cls}" x="${x.toFixed(1)}" y="${y.toFixed(1)}" ` +
          `width="${(cellW - 1).toFixed(1)}" height="${rowH.toFixed(1)}" rx="1.5" fill-opacity="${op.toFixed(2)}">` +
          `<title>${escapeText(`${s.label} · ${range}: ${c}`)}</title></rect>`
        );
      }
      parts.push(`<text x="${ML - 6}" y="${(y + rowH / 2 + 3).toFixed(1)}" text-anchor="end">${s.label}</text>`);
    });

    const yAxis = H - MB + 12;
    for (const hr of [0, 6, 12, 18]) {
      const x = ML + (hr / 24) * innerW;
      parts.push(`<text x="${x.toFixed(1)}" y="${yAxis}" text-anchor="${hr === 0 ? "start" : "middle"}">${hr}h</text>`);
    }
    parts.push(`<text x="${(ML + innerW).toFixed(1)}" y="${yAxis}" text-anchor="end">24h</text>`);

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

  // ---------- 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);
  }

  // ---------- training ----------
  // Per-exercise stats plus a consistency heatmap. Everything here is rolling
  // (last session / last 7 days / streak / last 14 days) rather than scoped to
  // the day picker — the point is keeping the habit up, not reviewing one day.
  const TRAINING_DAYS = 14;
  const expandedExercises = new Set(); // ids showing their instructions (per page load)

  function trainingStreakDays(times) {
    // Consecutive days with ≥1 session, counting back from today — or from
    // yesterday, so a streak isn't shown as broken before today's session
    // has had a chance to happen.
    const days = new Set(times.map(t => ymd(new Date(t))));
    const d = new Date();
    if (!days.has(ymd(d))) d.setDate(d.getDate() - 1);
    let streak = 0;
    while (days.has(ymd(d))) { streak++; d.setDate(d.getDate() - 1); }
    return streak;
  }

  function exerciseMeta(times) {
    if (times.length === 0) return "not yet trained";
    const weekFrom = startOfDay(new Date());
    weekFrom.setDate(weekFrom.getDate() - 6);
    const week = times.filter(t => t >= weekFrom.getTime()).length;
    const parts = [`last ${formatRelative(Math.max(...times))}`, `${week}× this week`];
    const streak = trainingStreakDays(times);
    if (streak >= 2) parts.push(`🔥 ${streak}-day streak`);
    return parts.join(" · ");
  }

  // Exercise × day grid: one row per exercise, one cell per day, opacity scaled
  // by that day's session count. Same idea as the hour heatmap, with days for
  // columns. Cells click through to the day picker via setChartSVG.
  function renderTrainingHeatmap(exercises, events) {
    const wrap = document.getElementById("training-chart-wrap");
    const svg  = document.getElementById("chart-training");
    if (exercises.length === 0) { wrap.hidden = true; return; }
    wrap.hidden = false;

    const N = TRAINING_DAYS;
    const from = startOfDay(new Date());
    from.setDate(from.getDate() - (N - 1));
    const dayList = [];
    const dayIndex = new Map(); // ymd -> column
    for (let i = 0; i < N; i++) {
      const d = new Date(from);
      d.setDate(d.getDate() + i);
      dayList.push(d);
      dayIndex.set(ymd(d), i);
    }
    const exIndex = new Map(exercises.map((x, i) => [x.id, i]));
    const counts = exercises.map(() => new Array(N).fill(0));
    for (const e of events) {
      if (e.type !== "training") continue;
      const r = exIndex.get(e.exerciseId);
      const c = dayIndex.get(ymd(new Date(e.at)));
      if (r !== undefined && c !== undefined) counts[r][c]++;
    }

    const W = 320;
    const ML = 70, MR = 8, MT = 6, MB = 18;
    const rowH = 16, rowGap = 4;
    const H = MT + exercises.length * (rowH + rowGap) - rowGap + MB;
    svg.setAttribute("viewBox", `0 0 ${W} ${H}`);
    const innerW = W - ML - MR;
    const cellW = innerW / N;

    const parts = [];
    exercises.forEach((x, r) => {
      const y = MT + r * (rowH + rowGap);
      const max = Math.max(1, ...counts[r]);
      for (let c = 0; c < N; c++) {
        const n = counts[r][c];
        const op = n === 0 ? 0.06 : 0.35 + 0.65 * (n / max);
        const d = dayList[c];
        const title = `${x.name} · ${d.toLocaleDateString(undefined, { weekday: "short", month: "short", day: "numeric" })}: ${n}`;
        parts.push(
          `<rect class="bar hm-cell hm-training" data-day="${ymd(d)}" ` +
          `x="${(ML + c * cellW).toFixed(1)}" y="${y.toFixed(1)}" ` +
          `width="${(cellW - 1.5).toFixed(1)}" height="${rowH}" rx="2" fill-opacity="${op.toFixed(2)}">` +
          `<title>${escapeText(title)}</title></rect>`
        );
      }
      const name = x.name.length > 12 ? x.name.slice(0, 11) + "…" : x.name;
      parts.push(`<text x="${ML - 6}" y="${(y + rowH / 2 + 3).toFixed(1)}" text-anchor="end">${escapeText(name)}</text>`);
    });

    const yAxis = H - MB + 12;
    parts.push(`<text x="${ML}" y="${yAxis}" text-anchor="start">${escapeText(dayList[0].toLocaleDateString(undefined, { month: "short", day: "numeric" }))}</text>`);
    parts.push(`<text x="${ML + innerW}" y="${yAxis}" text-anchor="end">Today</text>`);

    setChartSVG(svg, parts);
  }

  function renderTraining(events) {
    const list  = document.getElementById("training-list");
    const empty = document.getElementById("training-empty");
    const exercises = liveExercises();
    list.innerHTML = "";
    empty.hidden = exercises.length > 0;

    for (const ex of exercises) {
      const times = events
        .filter(e => e.type === "training" && e.exerciseId === ex.id)
        .map(e => e.at);

      const li = document.createElement("li");
      li.className = "exercise" + (expandedExercises.has(ex.id) ? " expanded" : "");

      const row  = document.createElement("div");
      row.className = "ex-row";
      const main = document.createElement("div");
      main.className = "ex-main";
      const nameEl = document.createElement("span");
      nameEl.className = "ex-name";
      nameEl.textContent = ex.name;
      const metaEl = document.createElement("span");
      metaEl.className = "ex-meta";
      metaEl.textContent = exerciseMeta(times);
      main.appendChild(nameEl);
      main.appendChild(metaEl);

      const logBtn = document.createElement("button");
      logBtn.type = "button";
      logBtn.className = "ex-log";
      logBtn.textContent = "Log";
      logBtn.addEventListener("click", (e) => {
        e.stopPropagation();
        const ev = addEvent("training", "", Date.now(), { exerciseId: ex.id });
        showSnackbar(`${ex.name} logged`, ev);
      });

      row.appendChild(main);
      row.appendChild(logBtn);
      row.addEventListener("click", () => {
        if (expandedExercises.has(ex.id)) expandedExercises.delete(ex.id);
        else expandedExercises.add(ex.id);
        li.classList.toggle("expanded");
      });

      const detail = document.createElement("div");
      detail.className = "ex-detail";
      const noteEl = document.createElement("p");
      noteEl.className = "ex-note";
      noteEl.textContent = ex.note || "No instructions yet — tap Edit to add how to train this.";
      const editBtn = document.createElement("button");
      editBtn.type = "button";
      editBtn.className = "ghost ex-edit";
      editBtn.textContent = "Edit";
      editBtn.addEventListener("click", (e) => {
        e.stopPropagation();
        openExerciseDialog(ex);
      });
      detail.appendChild(noteEl);
      detail.appendChild(editBtn);

      li.appendChild(row);
      li.appendChild(detail);
      list.appendChild(li);
    }

    renderTrainingHeatmap(exercises, events);
  }

  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;
    // Use the puppy's name in the sleep-timeline heading rather than assuming a
    // gender; fall back to a neutral phrase when no name is configured.
    const sleepTitle = document.getElementById("sleep-timeline-title");
    if (sleepTitle) sleepTitle.textContent = cfg.name ? `When ${cfg.name} sleeps` : "When sleeping";
  }

  function render() {
    const events = live();
    renderHeader();
    renderDayBar();
    renderBigClock(events);
    renderStats(events);
    renderLasts(events);
    renderTiming(events);
    renderSleepWindows(events);
    renderWakeWindows(events);
    renderWeekly(events);
    renderSleepTimeline(events);
    renderHourHeatmap(events);
    renderTraining(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 a server response back into local storage. Anything local with a
  // newer updatedAt than the server's copy wins — that covers items the user
  // added/edited during the in-flight sync request. Shared by the events and
  // exercises collections, which follow the same LWW contract.
  function mergeSynced(serverItems, load, save) {
    const localById = new Map(load().map(e => [e.id, e]));
    const merged = new Map();
    for (const se of serverItems) {
      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);
      }
    }
    save([...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();

      const exRes = await fetch("api/exercises/sync", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ exercises: loadExercises() }),
      });
      if (exRes.status === 401) { handleLoggedOut(); return; }
      if (!exRes.ok) throw new Error(`HTTP ${exRes.status}`);
      const exBody = await exRes.json();

      if (Array.isArray(exBody.exercises)) {
        mergeSynced(exBody.exercises, loadExercises, saveExercises);
      }
      if (Array.isArray(body.events)) {
        mergeSynced(body.events, loadAll, saveAll);
      }
      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 notePhotoPreview = document.getElementById("note-photo-preview");
  const noteWeightField  = document.getElementById("note-weight-field");
  const noteWeight       = document.getElementById("note-weight");
  const noteGramsField   = document.getElementById("note-grams-field");
  const noteGrams        = document.getElementById("note-grams");
  let pendingType        = null;
  let notePhotos         = []; // pending photos for this dialog: [{ blob, url }]
  // Whether the user has manually touched the date/time fields. While false the
  // dialog logs at the exact current millisecond rather than the minute-floored
  // input, so a just-logged event doesn't look up to ~59s old.
  let noteTimeEdited     = false;

  // An event can carry several photos: photoId holds their UUIDs
  // comma-separated. A legacy single id is just a one-element list, and the
  // server passes the string through untouched (photos themselves are
  // uploaded and fetched individually by UUID).
  function photoIdsOf(ev) {
    return (ev.photoId || "").split(",").filter(Boolean);
  }

  // A preview thumbnail with a remove button; shared by both dialogs.
  function photoThumb(url, onRemove) {
    const wrap = document.createElement("div");
    wrap.className = "photo-thumb";
    const img = document.createElement("img");
    img.alt = "";
    if (url) img.src = url;
    const rm = document.createElement("button");
    rm.type = "button";
    rm.className = "photo-thumb-remove";
    rm.setAttribute("aria-label", "Remove photo");
    rm.textContent = "×";
    rm.addEventListener("click", onRemove);
    wrap.appendChild(img);
    wrap.appendChild(rm);
    return wrap;
  }

  function renderNotePhotos() {
    notePhotoPreview.innerHTML = "";
    notePhotoPreview.hidden = notePhotos.length === 0;
    notePhotos.forEach((p, i) => {
      notePhotoPreview.appendChild(photoThumb(p.url, () => {
        URL.revokeObjectURL(p.url);
        notePhotos.splice(i, 1);
        renderNotePhotos();
      }));
    });
  }

  function clearNotePhotos() {
    for (const p of notePhotos) URL.revokeObjectURL(p.url);
    notePhotos = [];
    renderNotePhotos();
    notePhotoInput.value = "";
  }

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

  function noteDialogAt() {
    // Untouched time → stamp the exact current instant (sub-minute accurate).
    // Once the user picks a time, honor the input (minute precision is fine).
    if (!noteTimeEdited) return Date.now();
    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);
    noteTimeEdited = false; // "Now" means log at the current instant again
  });

  [noteDate, noteTime].forEach(el => {
    const markEdited = () => { noteTimeEdited = true; };
    el.addEventListener("change", markEdited);
    el.addEventListener("input", markEdited);
  });

  notePhotoBtn.addEventListener("click", () => notePhotoInput.click());
  notePhotoInput.addEventListener("change", async (e) => {
    for (const file of Array.from(e.target.files || [])) {
      try {
        const blob = await resizeImage(file);
        notePhotos.push({ blob, url: URL.createObjectURL(blob) });
      } catch (err) {
        alert("Couldn't process that photo: " + err.message);
      }
    }
    notePhotoInput.value = "";
    renderNotePhotos();
  });

  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 grams;
    if (pendingType === "eat" && noteGrams.value.trim() !== "") {
      const g = parseFloat(noteGrams.value);
      if (!(g > 0)) { alert("Enter the amount in grams, or leave it empty."); return; }
      grams = Math.round(g);
    }
    const photoIds = [];
    for (const p of notePhotos) {
      const id = uuid();
      try { await putPhoto(id, p.blob, false); }
      catch (err) {
        alert("Couldn't store photo locally: " + err.message);
        return;
      }
      photoIds.push(id);
    }
    addEvent(pendingType, noteInput.value.trim(), noteDialogAt(), { photoId: photoIds.join(","), weight, grams });
    pendingType = null;
    clearNotePhotos();
    noteDialog.close();
  });
  noteForm.querySelector('button[value="cancel"]').addEventListener("click", (e) => {
    e.preventDefault();
    pendingType = null;
    clearNotePhotos();
    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 editPhotoPreview = document.getElementById("edit-photo-preview");
  const editWeightField  = document.getElementById("edit-weight-field");
  const editWeight       = document.getElementById("edit-weight");
  const editGramsField   = document.getElementById("edit-grams-field");
  const editGrams        = document.getElementById("edit-grams");
  let editingId          = null;
  // The dialog's working set of photos, in display order. Existing photos are
  // { id, url } (url from photoSrc's page-lifetime cache — never revoked here);
  // newly picked ones are { blob, url } with a fresh object URL we own.
  let editPhotos         = [];

  function renderEditPhotos() {
    editPhotoPreview.innerHTML = "";
    editPhotoPreview.hidden = editPhotos.length === 0;
    editPhotos.forEach((p, i) => {
      editPhotoPreview.appendChild(photoThumb(p.url, () => {
        if (p.blob) URL.revokeObjectURL(p.url);
        editPhotos.splice(i, 1);
        renderEditPhotos();
      }));
    });
  }

  function resetEditPhotos() {
    for (const p of editPhotos) if (p.blob) URL.revokeObjectURL(p.url);
    editPhotos = [];
    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 : "";
    editGramsField.hidden = ev.type !== "eat";
    editGrams.value = (ev.type === "eat" && Number.isFinite(ev.grams) && ev.grams > 0) ? ev.grams : "";
    resetEditPhotos();
    for (const id of photoIdsOf(ev)) {
      editPhotos.push({ id, url: await photoSrc(id) });
    }
    renderEditPhotos();
    editDialog.showModal();
  }

  editPhotoBtn.addEventListener("click", () => editPhotoInput.click());
  editPhotoInput.addEventListener("change", async (e) => {
    for (const file of Array.from(e.target.files || [])) {
      try {
        const blob = await resizeImage(file);
        editPhotos.push({ blob, url: URL.createObjectURL(blob) });
      } catch (err) {
        alert("Couldn't process that photo: " + err.message);
      }
    }
    editPhotoInput.value = "";
    renderEditPhotos();
  });

  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 (!editGramsField.hidden) {
      if (editGrams.value.trim() === "") {
        patch.grams = undefined; // cleared → drop the amount
      } else {
        const g = parseFloat(editGrams.value);
        if (!(g > 0)) { alert("Enter the amount in grams, or leave it empty."); return; }
        patch.grams = Math.round(g);
      }
    }
    const photoIds = [];
    for (const p of editPhotos) {
      if (p.id) { photoIds.push(p.id); continue; }
      const id = uuid();
      try { await putPhoto(id, p.blob, false); }
      catch (err) { alert("Couldn't store photo locally: " + err.message); return; }
      photoIds.push(id);
    }
    patch.photoId = photoIds.join(",");
    updateEvent(editingId, patch);
    editingId = null;
    resetEditPhotos();
    editDialog.close();
  });

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

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

  // ---------- changelog dialog ----------
  // Shows the *loaded* build's full changelog: the plain URL is served
  // cache-first by the controlling service worker, so the list always matches
  // the version actually running (the update banner handles what's newer).
  const changelogDialog = document.getElementById("changelog-dialog");
  const changelogList   = document.getElementById("changelog-list");
  const changelogEmpty  = document.getElementById("changelog-empty");

  function formatChangelogDate(iso) {
    const [y, m, d] = (iso || "").split("-").map(Number);
    if (!y || !m || !d) return iso || "";
    return new Date(y, m - 1, d).toLocaleDateString(undefined, {
      year: "numeric", month: "short", day: "numeric",
    });
  }

  document.getElementById("changelog-btn").addEventListener("click", async () => {
    let entries = [];
    try {
      const res = await fetch("changelog.json");
      if (res.ok) {
        const body = await res.json();
        if (Array.isArray(body)) entries = body.filter(e => e && e.text);
      }
    } catch { /* fall through to empty state */ }

    changelogList.innerHTML = "";
    changelogEmpty.hidden = entries.length > 0;
    let lastDate = null;
    for (const e of entries) {
      if (e.date !== lastDate) {
        lastDate = e.date;
        const dt = document.createElement("li");
        dt.className = "changelog-date";
        dt.textContent = formatChangelogDate(e.date);
        changelogList.appendChild(dt);
      }
      const li = document.createElement("li");
      li.className = "changelog-entry";
      li.textContent = e.text;
      changelogList.appendChild(li);
    }
    changelogDialog.showModal();
  });

  // ---------- exercise dialog (add / edit a training exercise) ----------
  const exerciseDialog = document.getElementById("exercise-dialog");
  const exerciseForm   = document.getElementById("exercise-form");
  const exerciseTitle  = document.getElementById("exercise-title");
  const exerciseName   = document.getElementById("exercise-name");
  const exerciseNote   = document.getElementById("exercise-note");
  const exerciseDelete = document.getElementById("exercise-delete");
  let editingExerciseId = null;

  function openExerciseDialog(ex) {
    editingExerciseId = ex ? ex.id : null;
    exerciseTitle.textContent = ex ? "Edit exercise" : "Add exercise";
    exerciseName.value = ex ? ex.name : "";
    exerciseNote.value = ex ? (ex.note || "") : "";
    exerciseDelete.hidden = !ex;
    exerciseDialog.showModal();
    setTimeout(() => exerciseName.focus(), 50);
  }

  document.getElementById("exercise-add").addEventListener("click", () => openExerciseDialog(null));

  exerciseForm.querySelector('button[value="save"]').addEventListener("click", (e) => {
    e.preventDefault();
    const name = exerciseName.value.trim();
    if (!name) { alert("Give the exercise a name."); return; }
    const note = exerciseNote.value.trim();
    if (editingExerciseId) updateExercise(editingExerciseId, { name, note });
    else addExercise(name, note);
    editingExerciseId = null;
    exerciseDialog.close();
  });
  exerciseForm.querySelector('button[value="cancel"]').addEventListener("click", (e) => {
    e.preventDefault();
    editingExerciseId = null;
    exerciseDialog.close();
  });
  exerciseDelete.addEventListener("click", (e) => {
    e.preventDefault();
    if (editingExerciseId && confirm("Delete this exercise? Logged sessions stay in history.")) {
      deleteExercise(editingExerciseId);
    }
    editingExerciseId = null;
    exerciseDialog.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());
        localStorage.removeItem(exercisesKey());
      } catch { /* ignore */ }
      clearUser();
      deleteAccountDialog.close();
      location.reload();
    } catch (err) {
      deleteAccountError.textContent = err.message || "Something went wrong";
      deleteAccountError.hidden = false;
    } finally {
      deleteAccountConfirm.disabled = false;
    }
  });

  // ---------- quick-log snackbar ----------
  // A single tap on a quick-action logs the event at the current instant, then
  // shows a brief snackbar to undo it or add detail — so the two-tap dialog flow
  // is never required for a plain pee/poo/meal/sleep boundary. Weigh-ins still
  // open the dialog since they need a value.
  const snackbar     = document.getElementById("snackbar");
  const snackbarMsg  = document.getElementById("snackbar-msg");
  const snackbarUndo = document.getElementById("snackbar-undo");
  const snackbarNote = document.getElementById("snackbar-note");
  let snackbarEvent  = null;
  let snackbarTimer  = null;

  function hideSnackbar() {
    clearTimeout(snackbarTimer);
    snackbarTimer = null;
    snackbarEvent = null;
    snackbar.classList.remove("show");
    snackbar.hidden = true;
  }

  function showSnackbar(msg, ev) {
    snackbarEvent = ev;
    snackbarMsg.textContent = msg;
    snackbar.hidden = false;
    void snackbar.offsetWidth; // reflow so the fade-in transition runs
    snackbar.classList.add("show");
    clearTimeout(snackbarTimer);
    snackbarTimer = setTimeout(hideSnackbar, 5000);
  }

  function quickLog(type) {
    const ev = addEvent(type, "", Date.now());
    showSnackbar(`${EVENT_LABELS[type]} logged`, ev);
  }

  snackbarUndo.addEventListener("click", () => {
    if (snackbarEvent) deleteEvent(snackbarEvent.id);
    hideSnackbar();
  });
  snackbarNote.addEventListener("click", () => {
    const ev = snackbarEvent;
    hideSnackbar();
    if (ev) openEditDialog(ev);
  });

  // ---------- collapsible panels ----------
  // Each main section carrying a data-panel key can be folded by clicking its
  // heading; collapsed keys are remembered across reloads. State is device-global
  // (like the theme), so a single non-namespaced key is fine — it's not per-user
  // data. Only collapsed panels are stored, so newly added panels default open.
  const PANELS_KEY = "puppy-tracker:panels:v1";
  function loadPanelState() {
    try {
      const s = JSON.parse(localStorage.getItem(PANELS_KEY));
      return s && typeof s === "object" ? s : {};
    } catch { return {}; }
  }
  function savePanelState(state) {
    try { localStorage.setItem(PANELS_KEY, JSON.stringify(state)); } catch { /* ignore */ }
  }
  function initPanels() {
    const state = loadPanelState();
    document.querySelectorAll("main section[data-panel]").forEach(section => {
      const key = section.dataset.panel;
      const h2 = section.querySelector(":scope > h2");
      if (!h2) return;
      section.classList.add("collapsible");
      const collapsed = !!state[key];
      section.classList.toggle("collapsed", collapsed);
      h2.setAttribute("role", "button");
      h2.setAttribute("tabindex", "0");
      h2.setAttribute("aria-expanded", String(!collapsed));
      const toggle = () => {
        const nowCollapsed = section.classList.toggle("collapsed");
        h2.setAttribute("aria-expanded", String(!nowCollapsed));
        const s = loadPanelState();
        if (nowCollapsed) s[key] = true; else delete s[key];
        savePanelState(s);
      };
      h2.addEventListener("click", toggle);
      h2.addEventListener("keydown", (e) => {
        if (e.key === "Enter" || e.key === " ") { e.preventDefault(); toggle(); }
      });
    });
  }
  initPanels();

  // ---------- wiring ----------
  document.querySelectorAll("button.action").forEach(btn => {
    btn.addEventListener("click", () => {
      const type = btn.dataset.type;
      // Weigh-ins need a typed value and meals ask for grams, so those two
      // keep the full dialog.
      if (type === "weight" || type === "eat") { openNoteDialog(type); return; }
      quickLog(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();
    });

    // What the waiting build changes compared to the running one. The plain
    // URL is answered by the *old* controlling worker cache-first, i.e. the
    // loaded build's changelog; the cache-busting query misses every SW cache
    // and hits the network, i.e. the new build's changelog. Entries in the
    // fresh copy that the cached one lacks are exactly "new since this build".
    async function changelogDiff() {
      const load = async (url) => {
        try {
          const res = await fetch(url);
          if (!res.ok) return null;
          const body = await res.json();
          return Array.isArray(body) ? body : null;
        } catch {
          return null;
        }
      };
      const current = await load("changelog.json");
      const fresh   = await load(`changelog.json?v=${Date.now()}`);
      if (!fresh) return [];
      const seen = new Set((current || []).map(e => e && e.text));
      return fresh.filter(e => e && e.text && !seen.has(e.text));
    }

    function showUpdateBanner(worker) {
      waitingWorker = worker;
      updateBanner.hidden = false;
      const list = document.getElementById("update-changelog");
      list.hidden = true;
      list.innerHTML = "";
      changelogDiff().then(entries => {
        if (entries.length === 0) return;
        for (const e of entries.slice(0, 6)) {
          const li = document.createElement("li");
          li.textContent = e.text;
          list.appendChild(li);
        }
        list.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);
      renderSleepTimeline(evs);
      renderHourHeatmap(evs);
      renderTraining(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();
  })();
})();