Write down that a source can be empty without being broken

The two preceding changes make sentences in docs/ false. INGESTION.md
described `canParse` as a structural check without saying that "structural"
excludes the presence of a row — which is exactly the drift that let this
bug in — and described the Stage 1 gate as rejecting every empty parse.
SOURCES.md § 11 left a reader to conclude that an empty Infinity Nikki lane
means the source has died.

AGENTS.md gets the rule in both places somebody would look: § Working on
parsers, next to the bullet about a source resting on one row, and § Fandom
where the fourth template is described.

The general lesson is worth more than the incident. Any page that can list
nothing can produce this, so the guidance is about what identifies a page
versus what happens to be on it — not about this wiki.

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

docs/SOURCES.md

@@ -430,6 +430,22 @@ Two shapes the parser handles, both of which would otherwise lose or corrupt a r
 Asking the wiki's editors to state the zone on the Duration column would upgrade this source to
 exact instants, and remains the cheapest improvement available to it.
 
+**Update, 2026-09-03: this page goes empty between versions, and the source was reading that as a
+redesign.** With 2.7's events ended and 2.8 not yet listed, the wiki replaced both the `Current
+Events` and `Upcoming Events` tables with `There are no Events in this category`, leaving everything
+else — including twenty `Past Events` tables of identical shape — untouched. `canParse` identified
+the page by finding a *populated* table, so it threw `the source has likely been redesigned` at a
+page nobody had touched; four cycles of that reached the `broken` tier and the calendar went on
+holding a snapshot whose every row had expired on 27 August.
+
+The fix was in the pipeline, not in this assessment: `canParse` now identifies the page by its
+section headings, and `statesNoEvents` lets a parser report the page's own declaration of emptiness
+so the runner stores it as an answer instead of a failure (`docs/INGESTION.md` § The parser interface
+and § Stage 1). **So an empty Infinity Nikki lane is now the expected state between patches, not a
+symptom** — the thing to check before suspecting this source is whether the wiki is listing anything
+at all. It refills on its own when the next version is posted. The verdict on the source is
+unchanged and it stays built.
+
 ## 12. Thirteen Game8 hubs, swept on 2026-08-19 — two are worth building, eleven are not
 
 Not a P1 game between them: this section answers a direct request to check a list of Game8 game