server-persisted watch history with position + resume

- POST/GET /api/history: JSON file in data/history.json (50 entries
  kept, top 5 shown on home), upsert per (anime, episode)
- watch position saved every ~10s of playback + on pause/unload
- resume: opening an anime seeks to the saved position unless
  >=95% through (then starts fresh); position shown on home items
- drops localStorage; server is the source of truth (verified:
  fresh watch -> new session resumes at saved pos -> home lists it)

static/app.js

@@ -30,23 +30,24 @@ function showStreamError(msg) {
   if (player) player.append(p); else fail(new Error(msg));
 }
 
-// ---------- history ----------
-const HKEY = "aniweb.history";
-const hist = () => JSON.parse(localStorage.getItem(HKEY) || "[]");
-function pushHistory(entry) {
-  const h = hist().filter(x => !(x.slug_id === entry.slug_id && x.ep_id === entry.ep_id));
-  h.unshift(entry);
-  localStorage.setItem(HKEY, JSON.stringify(h.slice(0, 20)));
+// ---------- history (server-persisted, incl. watch position) ----------
+let history = [];
+async function refreshHistory() {
+  try { history = await api("/api/history"); } catch { /* home just shows empty */ }
 }
+function postHistory(entry) {
+  fetch("/api/history", {method: "POST", headers: {"Content-Type": "application/json"},
+    body: JSON.stringify(entry)}).catch(() => {});
+}
+const fmtPos = s => { s = Math.floor(s || 0); return `${Math.floor(s / 60)}:${String(s % 60).padStart(2, "0")}`; };
 
 function showHome() {
   main.innerHTML = "";
-  const h = hist();
-  if (!h.length) { main.append(el("p", "muted", "Search for an anime to get started.")); return; }
+  if (!history.length) { main.append(el("p", "muted", "Search for an anime to get started.")); return; }
   const sec = el("section");
   sec.append(el("h2", null, "Recently played"));
-  for (const x of h) {
-    const b = el("button", "hist-item", `${x.title} — Ep ${x.ep} (${x.lang === "eng" ? "dub" : "sub"})`);
+  for (const x of history.slice(0, 5)) {
+    const b = el("button", "hist-item", `${x.title} — Ep ${x.ep} (${x.lang === "eng" ? "dub" : "sub"}) · ${fmtPos(x.pos)}`);
     b.onclick = () => location.href = `?anime=${x.slug_id}&season=${x.season_id}&ep=${x.ep_id}&lang=${x.lang}`;
     sec.append(b);
   }
@@ -128,7 +129,7 @@ async function showAnime(slug_id, opts = {}) {
     if (cur) { markActive(cur); play(opts.ep, cur.dataset.no); }
   } else {
     // default: resume last watched ep of this season, else start at ep 1
-    const h = hist().find(x => x.slug_id === slug_id && x.season_id === seasonId);
+    const h = history.find(x => x.slug_id === slug_id && x.season_id === seasonId);
     const auto = h ? h.ep_id : +eps.querySelector(".ep")?.dataset.ep;
     if (auto) {
       const cur = [...eps.children].find(b => +b.dataset.ep === auto);
@@ -154,6 +155,8 @@ function videoEl() {
 
 function stopHls() { if (hls) { hls.destroy(); hls = null; } }
 
+let currentEp = null, lastSavedPos = 0;
+
 async function play(ep_id, ep_no) {
   try {
     const s = await api(`/api/episode/${ep_id}/stream?lang=${lang}`);
@@ -171,16 +174,37 @@ async function play(ep_id, ep_no) {
     });
     hls.loadSource("/stream/" + s.token);
     hls.attachMedia(v);
+    currentEp = {ep_id, ep_no, v};
+    lastSavedPos = 0;
+    const saved = history.find(x => x.slug_id === detail.slug_id && x.ep_id === ep_id);
+    if (saved?.pos > 10) {
+      v.addEventListener("loadedmetadata", () => {
+        if (saved.pos < v.duration * 0.95) v.currentTime = saved.pos;
+      }, {once: true});
+    }
     v.onerror = () => showStreamError("media error: " + (v.error?.message || v.error?.code));
     v.play().catch(() => showPlayOverlay(v)); // autoplay blocked (no user gesture) -> visible prompt
+    watchPos(v);
+    postHistory({title: detail.name, slug_id: detail.slug_id, season_id: seasonId,
+                 ep_id, lang, ep: ep_no, pos: saved?.pos || 0});
   } catch (e) {
     showStreamError(e.message);
   }
-  pushHistory({title: detail.name, slug_id: detail.slug_id, season_id: seasonId,
-               ep_id, lang, ep: ep_no});
   document.title = `${detail.name} E${ep_no} — ani-web`;
 }
 
+function watchPos(v) {
+  const save = () => {
+    if (!currentEp || v.currentTime <= 3) return;
+    lastSavedPos = v.currentTime;
+    postHistory({title: detail.name, slug_id: detail.slug_id, season_id: seasonId,
+                 ep_id: currentEp.ep_id, lang, ep: currentEp.ep_no, pos: v.currentTime});
+  };
+  v.addEventListener("timeupdate", () => { if (v.currentTime - lastSavedPos >= 10) save(); });
+  v.addEventListener("pause", save);
+  window.addEventListener("pagehide", save);
+}
+
 function showPlayOverlay(v) {
   const o = el("button", "play-overlay", "▶ click to play");
   o.onclick = () => { v.play(); o.remove(); };
@@ -189,6 +213,7 @@ function showPlayOverlay(v) {
 
 // ---------- boot ----------
 (async () => {
+  await refreshHistory();
   const p = new URLSearchParams(location.search);
   try {
     if (p.get("q")) await showSearch(p.get("q"));