Identify the Infinity Nikki page by its headings, not by finding a row

The wiki emptied both its Current and Upcoming tables on 2026-09-03 — 2.7's
events had ended and 2.8 was not listed yet — and said so in words: "There
are no Events in this category". Nothing else moved; Past Events still
carries twenty tables of the same shape.

`isInfinityNikkiEventPage` looked for a *populated* table, so it read that
as a redesign. The source spent four cycles reporting "the source has
likely been redesigned" at a page nobody had touched, reached the broken
tier, and went on serving a snapshot whose every row expired on 27 August.

A check that reads data cannot tell a rewrite from a quiet week. It now
reads the section headings, which an empty table does not take with it —
either heading rather than both, since requiring the pair would fail the
source over a renamed heading it does not even read, and one already
separates this page from the other three Fandom templates. docs/INGESTION.md
asked for structural checks all along; this one had drifted into content.

`statesNoEvents` then reports the page's own declaration, so the runner can
tell an answer from a failure. It insists on the statement rather than an
empty table, because a redesign yields an empty table too.

The emptied page is pinned as a fixture: an empty answer is a shape, and it
is the one that used to read as a redesign.

Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>

fixtures/nikki/fandom-events-2026-09-03.expected.json

@@ -0,0 +1 @@
+[]

src/ingest/parsers/fandom.ts

@@ -440,13 +440,61 @@ function nikkeTitle(cell: string): string | null {
 /** Headings whose tables are a schedule our readers can act on. */
 const IN_INCLUDED_SECTION = /^(current|upcoming) events$/i;
 
+/** The page's own words when a section is currently listing nothing. */
+const IN_STATES_EMPTY = /There are no Events in this category/i;
+
+/** Every `<h2>` on the page, flattened to lower-case text. */
+function h2Headings(rendered: string): Set<string> {
+  const flat = rendered.replace(EDIT_SECTION, "").replace(/\s+/g, " ");
+  const out = new Set<string>();
+  for (const node of flat.matchAll(/<h2\b[^>]*>([\s\S]*?)<\/h2>/gi)) {
+    out.add(text(node[1] ?? "").trim().toLowerCase());
+  }
+  return out;
+}
+
 /**
  * True for the Infinity Nikki wiki's `Event` page, and the gate on the branch
- * below. Asserts the heading *and* the table shape, because the page's
- * `Permanent Events` table shares neither.
+ * below.
+ *
+ * **Identity only — never the presence of a row.** This asserted a populated
+ * `Current`/`Upcoming` table until 2026-09-03, which conflated the two things a
+ * tripwire has to keep apart: a page that was rewritten, and a game that has
+ * nothing on. Infinity Nikki emptied both tables the week 2.7's events ended
+ * and 2.8 was not yet listed, and the source spent four cycles reporting
+ * `the source has likely been redesigned` at a page whose markup had not moved
+ * — long enough to reach the `broken` tier and fail the workflow. `canParse` is
+ * documented as a *structural* check for exactly this reason
+ * (docs/INGESTION.md § The adapter registry), so it reads the section headings,
+ * which an empty table does not take with it.
+ *
+ * *Either* heading, not both — the same doc's warning against over-fitting. The
+ * live page carries both, but requiring the pair would fail the source over a
+ * renamed heading it does not even read, and one is already unique: the other
+ * three Fandom templates carry neither. `Past Events` is deliberately not in
+ * the set, or an archive with nothing current would identify as this page.
  */
 function isInfinityNikkiEventPage(rendered: string): boolean {
-  return infinityNikkiTables(rendered).length > 0;
+  const headings = h2Headings(rendered);
+  return headings.has("current events") || headings.has("upcoming events");
+}
+
+/**
+ * True when this page tells us, in its own words, that it currently lists no
+ * events — the state Infinity Nikki sits in between versions.
+ *
+ * This is what lets the refresh gate tell "we read the page and there is
+ * nothing on" from "we read nothing", and it is deliberately the page's
+ * statement rather than a row count: a redesign that broke every selector would
+ * also yield zero rows, and storing *that* as an empty snapshot is the silent
+ * emptying of a calendar the zero-events gate exists to prevent.
+ */
+function infinityNikkiStatesNoEvents(rendered: string): boolean {
+  if (!isInfinityNikkiEventPage(rendered)) return false;
+  // A table we can still read means the page is listing something, whatever
+  // else it says further down.
+  if (infinityNikkiTables(rendered).length > 0) return false;
+  return IN_STATES_EMPTY.test(rendered);
 }
 
 interface InTable {
@@ -765,5 +813,12 @@ export const fandomParser: SourceParser = {
       isInfinityNikkiEventPage(rendered)
     );
   },
+  statesNoEvents(body: string): boolean {
+    const rendered = renderedHtml(body);
+    if (rendered === null) return false;
+    // Only the Infinity Nikki template states this. The other three say nothing
+    // either way when they are empty, so they keep the strict gate.
+    return infinityNikkiStatesNoEvents(rendered);
+  },
   parse: parseFandomEventsPage,
 };

test/adapters/game8.test.ts

@@ -51,6 +51,11 @@ const CASES: Array<{ adapter: Adapter; fixture: string }> = [
   { adapter: adapter("uma-game8-events"), fixture: "fixtures/uma/game8-events-2026-08-19" },
   { adapter: adapter("nikke-fandom-events"), fixture: "fixtures/nikke/fandom-events-2026-08-19" },
   { adapter: adapter("nikki-fandom-events"), fixture: "fixtures/nikki/fandom-events-2026-08-19" },
+  // The same page a week later, listing nothing: 2.7's events had ended and 2.8
+  // was not up yet, so both tables read "There are no Events in this category."
+  // Pinned because an empty answer is a shape too — it is what the detector
+  // used to read as a redesign.
+  { adapter: adapter("nikki-fandom-events"), fixture: "fixtures/nikki/fandom-events-2026-09-03" },
   // Honkai Impact 3rd. Every boundary in this expected file is a week-bucket
   // edge the source labels `ESTIMATED WEEK`, not an announced date — see
   // src/ingest/parsers/arustats.ts and docs/SOURCES.md § 14.
@@ -1767,3 +1772,54 @@ describe("Infinity Nikki wiki (the fourth Fandom template)", () => {
     expect(shop?.summary).toBeTruthy();
   });
 });
+
+describe("Infinity Nikki wiki between versions (the page states it is empty)", () => {
+  const nikki = adapter("nikki-fandom-events");
+  const emptied = "fixtures/nikki/fandom-events-2026-09-03";
+  const populated = "fixtures/nikki/fandom-events-2026-08-19";
+
+  function parse(html: string) {
+    return nikki.parse(html, {
+      now: NOW,
+      sourceUrl: nikki.url,
+      sourceId: nikki.id,
+      game: nikki.game,
+    });
+  }
+
+  test("still recognises the template when both tables have been emptied", async () => {
+    // 2.7's events ended on 27 August and 2.8 was not listed yet, so the wiki
+    // replaced both tables with "There are no Events in this category." The
+    // page is otherwise untouched — `Past Events` still carries twenty tables
+    // of the same shape. A detector that needs a populated row reads that as a
+    // redesign and the runner reports a broken source that is merely quiet.
+    const html = await Bun.file(`${emptied}.html`).text();
+    expect(fandomParser.canParse(html)).toBe(true);
+    expect(() => parse(html)).not.toThrow();
+    expect(parse(html)).toEqual([]);
+  });
+
+  test("says the page states no events, and says it only when the page does", async () => {
+    // The distinction the refresh gate turns on: a page that tells us it lists
+    // nothing is a source we read correctly, not one that broke. Anything
+    // weaker than the page's own words would let a real redesign through as an
+    // empty calendar, which is the failure the zero-events gate exists for.
+    const empty = await Bun.file(`${emptied}.html`).text();
+    const full = await Bun.file(`${populated}.html`).text();
+    expect(fandomParser.statesNoEvents?.(empty)).toBe(true);
+    expect(fandomParser.statesNoEvents?.(full)).toBe(false);
+  });
+
+  test("does not claim emptiness for the other three Fandom templates", async () => {
+    // `statesNoEvents` is asked of every Fandom source, so a loose check would
+    // let a redesigned FGO or Nikke page store an empty snapshot.
+    for (const fixture of [
+      "fixtures/fgo/fandom-events-2026-08-18",
+      "fixtures/nikke/fandom-events-2026-08-19",
+      "fixtures/r1999/fandom-events-2026-08-17",
+    ]) {
+      const html = await Bun.file(`${fixture}.html`).text();
+      expect(fandomParser.statesNoEvents?.(html)).toBe(false);
+    }
+  });
+});