fix(build): pick a source's own fixture, not a sibling page's on the same site

build-feed globbed fixtures by site (`fandom-*`), so a second Fandom page
for a game, such as Genshin's Miliastra Pass beside its event page, would
have handed its fixture to the events parser. pickFixture matches the
source's whole name followed by a date. Every fixture already follows
that name, and the built feed is unchanged (206 events, same ids).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

scripts/build-feed.ts

@@ -12,7 +12,7 @@
 import { ADAPTERS } from "../src/ingest/adapters/index.ts";
 import { sourceHealth } from "../src/ingest/health.ts";
 import { mergeEvents } from "../src/ingest/merge.ts";
-import { SnapshotStore, freshnessAt } from "../src/ingest/snapshots.ts";
+import { SnapshotStore, freshnessAt, pickFixture } from "../src/ingest/snapshots.ts";
 import { EventFeed, SCHEMA_VERSION, type SourceHealth } from "../src/shared/feed.ts";
 import type { GachaEvent, GameId } from "../src/shared/schema.ts";
 
@@ -22,17 +22,16 @@ const snapshots = new SnapshotStore(process.env["SNAPSHOT_DIR"] ?? "snapshots");
 /**
  * Newest fixture for one *source*, not one game.
  *
- * A game can have several sources, and fixtures are named `<site>-events-<date>`
- * against adapter ids of `<game>-<site>-events`. Globbing by game alone hands
- * one site's page to another site's parser.
+ * A game can have several sources, and fixtures are named `<id less the
+ * game>-<date>` (`fandom-events-2026-09-12` for `genshin-fandom-events`).
+ * Globbing by game alone, or by site, hands one page to another page's parser —
+ * see `pickFixture`.
  */
 async function latestFixture(adapterId: string, game: GameId) {
-  const site = adapterId.replace(`${game}-`, "").replace(/-events$/, "");
-  const pattern = `fixtures/${game}/${site}-*.html`;
-  const files = [...new Bun.Glob(pattern).scanSync(".")].sort();
-  const file = files.at(-1);
+  const files = [...new Bun.Glob(`fixtures/${game}/*.html`).scanSync(".")];
+  const file = pickFixture(adapterId, game, files);
   if (file === undefined) {
-    throw new Error(`no fixture found for ${adapterId} (${pattern})`);
+    throw new Error(`no fixture found for ${adapterId} (fixtures/${game}/${adapterId.slice(game.length + 1)}-<date>.html)`);
   }
   return { file, html: await Bun.file(file).text() };
 }

src/ingest/snapshots.ts

@@ -404,3 +404,18 @@ export function freshnessAt(snapshot: Snapshot): string {
     ? confirmed
     : snapshot.meta.contentChangedAt;
 }
+
+/**
+ * The newest checked-in fixture for one *source*, from `files`, or undefined.
+ *
+ * Fixtures are named `<id without the game>-<YYYY-MM-DD>.html`: `fandom-events-2026-09-12`
+ * for `genshin-fandom-events`. The name must be followed directly by the date —
+ * a glob of `fandom-*` would hand `genshin-fandom-miliastra-pass`'s page to the
+ * events parser, a second page on the same site being exactly the case that
+ * shares a prefix. Sorted by name, so the newest date is last.
+ */
+export function pickFixture(adapterId: string, game: string, files: readonly string[]): string | undefined {
+  const name = adapterId.slice(game.length + 1);
+  const own = new RegExp(`(^|/)${name.replace(/[.*+?^${}()|[\]\\]/g, "\\$&")}-\\d{4}-\\d{2}-\\d{2}\\.html$`);
+  return files.filter((f) => own.test(f)).sort().at(-1);
+}

test/snapshots.test.ts

@@ -1,3 +1,4 @@
+import { pickFixture } from "../src/ingest/snapshots.ts";
 import { afterEach, beforeEach, describe, expect, test } from "bun:test";
 import { statSync } from "node:fs";
 import { mkdtemp, readdir, rm, writeFile } from "node:fs/promises";
@@ -454,3 +455,29 @@ describe("freshnessAt", () => {
     ).toBe(T0);
   });
 });
+
+describe("pickFixture: a source's own fixture, never a sibling's", () => {
+  const files = [
+    "fixtures/genshin/fandom-events-2026-09-12.html",
+    "fixtures/genshin/fandom-miliastra-pass-2026-10-16.html",
+    "fixtures/genshin/game8-events-2026-08-14.html",
+  ];
+
+  test("an -events source keeps its old names", () => {
+    expect(pickFixture("genshin-fandom-events", "genshin", files)).toBe(
+      "fixtures/genshin/fandom-events-2026-09-12.html",
+    );
+  });
+
+  test("a second page on the same site does not take the events page's fixture, or give it its own", () => {
+    expect(pickFixture("genshin-fandom-miliastra-pass", "genshin", files)).toBe(
+      "fixtures/genshin/fandom-miliastra-pass-2026-10-16.html",
+    );
+  });
+
+  test("the newest date wins, and nothing matches nothing", () => {
+    expect(pickFixture("genshin-game8-events", "genshin", [...files, "fixtures/genshin/game8-events-2026-09-01.html"]))
+      .toBe("fixtures/genshin/game8-events-2026-09-01.html");
+    expect(pickFixture("genshin-fandom-other", "genshin", files)).toBeUndefined();
+  });
+});