history: flag rows whose slug no longer means the same anime

Provider switch (anidb -> hianime-first) left anidb-era rows whose slugs
200 on hianime as a DIFFERENT anime: /watch/jujutsu-kaisen-2552 is now
Burning Kabaddi (the trailing number is a hianime id), and the stored
anidb ep id doesn't even exist in that anime's list — the row rendered
as watched JJK but linked to the wrong show.

Client-side validation (no data migration): every history row's slug is
checked against GET /api/anime/{slug} once per slug; title mismatch (or
a dead slug) marks the entry stale. Stale rows:
- home: one card per stale anime above the hero + 'history ->' link
- history page: separate 'Moved or renamed on the source' section
Each card: title, 'find it ->' (search by stored title) and x (remove,
same endpoint as regular cards). Current rows are untouched: a hianime
slug whose details name matches the stored title passes.

Tests: API contract for a stale row (deletable while on the board);
live browser test (gated) with the real jujutsu-kaisen-2552 row:
remap card renders, card doesn't link to the wrong slug, find-it
lands on the title's search.

static/app.js

@@ -127,7 +127,53 @@ const bar = (x, cls) => {
   b.append(Object.assign(el("div", "bar-fill"), {style: `width:${p}%`}));
   return b;
 };
-const histHref = x => `?anime=${x.slug_id}&season=${x.season_id}&ep=${x.ep_id}&lang=${x.lang}`;
+function histHref(x) { return `?anime=${x.slug_id}&season=${x.season_id}&ep=${x.ep_id}&lang=${x.lang}`; }
+
+// ---------- stale-entry remap (provider switch) ----------
+// History rows written while anidb was the source carry anidb slugs/ids. Under
+// hianime-first dispatch, /watch/{anidb-slug} often 200s as a DIFFERENT anime
+// (id 2552 = Burning Kabaddi) while the anidb ep id silently dies (not in that
+// anime's list) — the row then links to the wrong show. Validate every row
+// against the details endpoint; mismatch or dead slug -> remap board.
+const _norm = s => String(s || "").toLowerCase().replace(/[^a-z0-9]/g, "");
+const _match = (a, b) => {
+  const x = _norm(a), y = _norm(b);
+  return !!(x && y && (x === y || x.includes(y) || y.includes(x)));
+};
+const _remap = {};
+async function checkEntry(x) {
+  if (x._remapped) return true;
+  if (_remap[x.slug_id] !== undefined) { x._remapped = _remap[x.slug_id]; return !_remap[x.slug_id]; }
+  let d;
+  try { d = await api(`/api/anime/${x.slug_id}`); } catch { d = null; }
+  const ok = !!(d && d.name && _match(d.name, x.title));
+  _remap[x.slug_id] = !ok;
+  x._remapped = !ok;
+  return ok;
+}
+function remapCard(x) {
+  const c = el("a", "card hist remap");
+  c.append(poster(x.poster, x.title),
+           el("div", "card-name", `"${x.title}" \u2014 not found on the current source`));
+  const row = el("div", "chips");
+  const go = el("button", "tiny", "find it \u2192");
+  go.onclick = e => { e.preventDefault(); e.stopPropagation(); location.href = "?q=" + encodeURIComponent(x.title || ""); };
+  const del = el("button", "del", "\u00d7");
+  del.title = "remove from history";
+  del.onclick = async e => {
+    e.preventDefault();
+    e.stopPropagation();
+    await fetch(BASE + "api/history?slug_id=" + encodeURIComponent(x.slug_id) +
+                "&ep_id=" + encodeURIComponent(x.ep_id), {method: "DELETE", headers: {"X-Aniweb": "1"}});
+    c.remove();
+    const i = history.indexOf(x);
+    if (i >= 0) history.splice(i, 1);
+    toast("Removed from history", {label: "Undo", fn: () => postHistory(x)});
+  };
+  row.append(go, del);
+  c.append(row);
+  return c;
+}
 // one entry per anime (latest row wins), newest first
 const byShow = () => {
   const m = new Map();
@@ -189,6 +235,8 @@ function showHome() {
     return;
   }
   const hero = history[0];
+  main.append(remapBoard());
+  if (hero && hero._remapped) return;
   // 1. continue-watching hero
   const sec = el("section", "hero-sec");
   const card = el("a", "hero");
@@ -467,6 +515,22 @@ function langLabel() { return lang === "eng" ? "▶ dub" : "▶ sub"; }
 // ---------- history page (full list + delete + client-side filter) ----------
 const histClass = x => x.dur > 0 && x.pos >= x.dur * 0.95 ? "done"
   : (x.t && Date.now() / 1000 - x.t > 7 * 86400 ? "hold" : "watching");
+function remapBoard() {
+  // home: one stale card per stale anime (latest row), above the hero, so a
+  // switched-source user sees the remap CTA before the wrong-show hero
+  const m = new Map();
+  for (const x of history) if (x._remapped && (!m.has(x.slug_id) || x.t > m.get(x.slug_id).t)) m.set(x.slug_id, x);
+  const out = [];
+  if (m.size) {
+    out.push(el("div", "sec-head").append(
+      el("h2", null, "Moved or renamed on the source \u2014 pick the right one"),
+      link("history \u2192", "?history")));
+    const grid = el("div", "grid mini");
+    for (const x of m.values()) grid.append(remapCard(x));
+    out.push(grid);
+  }
+  return out;
+}
 async function showHistory() {
   document.title = "History \u2014 ani-web";
   skel(10);
@@ -474,6 +538,7 @@ async function showHistory() {
   main.innerHTML = "";
   main.append(el("h2", null, "History"));
   if (!items.length) { main.append(el("p", "muted", "Nothing here.")); focusMain(); return; }
+  await Promise.all(items.map(checkEntry));
   main.append(...histBoard(items));
   focusMain();
 }
@@ -576,12 +641,14 @@ function topAnime(d, n = 0) {
   return ta;
 }
 function histBoard(items, limit = 0) {
+  const good = items.filter(x => !x._remapped);
+  const stale = items.filter(x => x._remapped);
   const labels = {all: "all", watching: "watching", done: "completed", hold: "on hold"};
   let active = "all";
   const chips = el("div", "chips");
   const grid = el("div", "grid");
   const draw = () => {
-    let f = items.filter(x => active === "all" || histClass(x) === active);
+    let f = good.filter(x => active === "all" || histClass(x) === active);
     if (limit) f = f.slice(0, limit);
     grid.replaceChildren(...f.map(histCard));
     for (const c of chips.children) c.classList.toggle("on", c.dataset.f === active);
@@ -593,7 +660,15 @@ function histBoard(items, limit = 0) {
     chips.append(b);
   }
   draw();
-  return [chips, grid];
+  const out = [chips, grid];
+  if (stale.length) {
+    out.push(el("div", "sec-head").append(
+      el("h2", null, "Moved or renamed on the source \u2014 pick the right one")));
+    const sgrid = el("div", "grid mini");
+    for (const x of stale) sgrid.append(remapCard(x));
+    out.push(sgrid);
+  }
+  return out;
 }
 
 function heatMap(byDay, days) {
@@ -1169,6 +1244,7 @@ window.addEventListener("pagehide", () => savePos(0, true));  // keepalive: a pl
   } catch { /* not logged in: api() already redirected to /login */ }
   statusPill();
   await refreshHistory();
+  await Promise.all(history.map(checkEntry));
   const p = new URLSearchParams(location.search);
   try {
     if (p.get("q")) await showSearch(p.get("q"));

tests/test_api.py

@@ -506,3 +506,25 @@ def test_fetch_parallel_stitches_range_lanes():
     finally:
         u._session = real
         u._get = real_get
+
+
+def test_stale_entries_surfaced_as_remappable(base=BASE):
+    # provider switch left anidb-era rows: their slug 200s on hianime as a
+    # DIFFERENT anime (id 2552 = Burning Kabaddi). The client flags the
+    # mismatch; the API contract is unchanged — the entry is deletable by
+    # slug+ep while it sits on the remap board.
+    jar = login("bob", "bobpw12345", base)
+    stale = {"title": "Jujutsu Kaisen", "slug_id": "jujutsu-kaisen-2552",
+             "season_id": 2552, "ep_id": 35996, "lang": "jpn", "ep": 1, "pos": 42}
+    good = {"title": "Seed Anime", "slug_id": "seed-1", "season_id": 1,
+            "ep_id": 1, "lang": "eng", "ep": 1, "pos": 10}
+    assert req("POST", "/api/history", stale, jar=jar, base=base) == 200
+    assert req("POST", "/api/history", good, jar=jar, base=base) == 200
+    all_ = _json("GET", "/api/history?all=1", jar=jar, base=base)
+    got = [x for x in all_ if x["slug_id"] == "jujutsu-kaisen-2552"]
+    assert got and got[0]["ep_id"] == 35996 and got[0]["pos"] == 42, got
+    removed = _json("DELETE", "/api/history?slug_id=jujutsu-kaisen-2552&ep_id=35996",
+                    jar=jar, base=base)
+    assert removed["removed"] >= 1, removed
+    all_ = _json("GET", "/api/history?all=1", jar=jar, base=base)
+    assert not [x for x in all_ if x["slug_id"] == "jujutsu-kaisen-2552"], all_

tests/test_browser.py

@@ -450,3 +450,43 @@ async def _autoplay_blocked():
             timeout=120000, polling=250)
         assert not errors, errors
         await browser.close()
+
+
+def test_stale_history_remap_board():
+    asyncio.run(_stale_history_remap_board())
+
+
+async def _stale_history_remap_board():
+    # provider switch (anidb -> hianime) left rows whose anidb slug 200s on
+    # hianime as a DIFFERENT anime (jujutsu-kaisen-2552 = Burning Kabaddi).
+    # The history page must flag it for remap instead of linking to that show.
+    jar = http.cookiejar.CookieJar()
+    op = urllib.request.build_opener(urllib.request.HTTPCookieProcessor(jar))
+    op.open(urllib.request.Request(BASE + "/login",
+              data=json.dumps({"username": "erin", "password": "erinpw12345"}).encode(),
+              headers={"Content-Type": "application/json", "X-Aniweb": "1"}, method="POST"))
+    op.open(urllib.request.Request(BASE + "/api/history",
+              data=json.dumps({"title": "Jujutsu Kaisen", "slug_id": "jujutsu-kaisen-2552",
+                               "season_id": 2552, "ep_id": 35996, "lang": "jpn", "ep": 1,
+                               "pos": 42}).encode(),
+              headers={"Content-Type": "application/json", "X-Aniweb": "1"}, method="POST"))
+
+    async with async_playwright() as p:
+        browser = await p.chromium.launch(args=LAUNCH_ARGS)
+        page = await (await browser.new_context()).new_page()
+        errors = []
+        page.on("pageerror", lambda e: errors.append(str(e)))
+        await _login(page, "erin", "erinpw12345")
+        await page.goto(BASE + "/?history")
+        await page.wait_for_function(
+            "document.querySelector('a.card.remap')", timeout=60000, polling=POLL)
+        stale = page.locator("a.card.remap", has_text="Jujutsu Kaisen")
+        assert "not found" in await stale.inner_text()
+        # the card must not link to the wrong-slug detail page; find-it goes
+        # to the title's search instead
+        assert not await stale.get_attribute("href")
+        await stale.locator("button:has-text('find it')").click(force=True)
+        await page.wait_for_function(
+            "location.search.includes('q=')", timeout=15000, polling=POLL)
+        assert not errors, errors
+        await browser.close()