Tell a broken source apart from a stale one

CI failed on Infinity Nikki yielding no events, and was wrong to. Its
snapshot parses to six events; every one of them had ended by the morning
the build ran. The parser is fine — `--now 2026-08-14` gives six, today
gives none — and the page simply has nothing current left on it.

eventCount is counted after expired events are dropped, so "this parser has
stopped reading a redesigned page" and "this page's events have all
finished" arrived as the same zero. Only the first means our code is wrong,
and only the first should redden a build. So the feed now records what each
document yields parsed as of its own capture date, before expiry, and the
check fails on that instead.

Nikki cannot refresh itself out of this, either: docs/SOURCES.md records
that Fandom refuses the Actions runner. A lane with an empty calendar is a
real problem, but it is a refresh problem, so it is reported on the build
log and left visible rather than thrown.

parsedCount is nullable and defaulted, never required: the client validates
the whole feed with safeParse and the service worker serves the last feed it
downloaded, so a required field would have made every cached feed fail
validation and taken the offline promise with it. Null also covers a source
whose bytes were never confirmed live — there is no date to parse "as of",
and a build is not failed on missing information.

The rule moved to shared/feed.ts. A test did pin the old one, by grepping
the workflow for the string — which proved the check existed, never that it
was right.

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

src/shared/feed.ts

@@ -15,7 +15,25 @@ export const SourceHealth = z.object({
   game: GameId,
   url: z.string().url(),
   lastSuccessAt: z.string().datetime().nullable(),
+  /** Events this source contributed to the feed — after expired ones are dropped. */
   eventCount: z.number().int().nonnegative(),
+  /**
+   * Events the document yields when parsed as of its own capture date, before
+   * anything is dropped for having ended.
+   *
+   * The pair is what separates a broken source from a stale one. `eventCount`
+   * alone cannot: a parser that has stopped reading a redesigned page and a
+   * page whose every event has since finished both report zero, and only the
+   * first means our code is wrong.
+   *
+   * **Nullable and defaulted, never required.** The client validates the whole
+   * feed with `EventFeed.safeParse`, and the service worker serves the last
+   * feed it downloaded — so a required field here would make every cached feed
+   * fail validation and take the offline promise with it. Null means an older
+   * feed that never recorded this, which is an absence of information rather
+   * than evidence of a fault.
+   */
+  parsedCount: z.number().int().nonnegative().nullable().default(null),
 });
 
 export const EventFeed = z.object({
@@ -88,3 +106,36 @@ export function freshness(
 
   return { refreshedAt, stale };
 }
+
+/**
+ * Sources whose document yielded nothing at all.
+ *
+ * This is the failure a parser-only pipeline is most prone to and that nothing
+ * else would surface: a page is redesigned, the parser reads it as empty, and
+ * one game's calendar goes blank while the total stays comfortably healthy.
+ * Worth failing a build over.
+ *
+ * A source whose events have merely all ended is not this, and CI said it was
+ * — the check read `eventCount`, which is measured after expiry, so a stale
+ * page and a broken parser arrived as the same zero. Only an explicit zero
+ * counts here; a null is an older feed that never recorded the figure, and
+ * failing on missing information would be the same mistake in a new place.
+ */
+export function brokenSources(sources: readonly SourceHealth[]): SourceHealth[] {
+  return sources.filter((s) => s.parsedCount === 0);
+}
+
+/**
+ * Sources that parsed fine but have nothing current left to show.
+ *
+ * A real problem — that lane renders an empty calendar — but a refresh
+ * problem rather than a code one, and some of these cannot be refreshed from
+ * CI at all (`docs/SOURCES.md` records which hosts refuse the runner). So it
+ * is reported and left visible rather than thrown, the same way the app shows
+ * a stale timestamp rather than pretending the calendar is current.
+ */
+export function staleSources(sources: readonly SourceHealth[]): SourceHealth[] {
+  return sources.filter(
+    (s) => s.parsedCount !== null && s.parsedCount > 0 && s.eventCount === 0,
+  );
+}