diigo-cache: a short page before the stated end peeks at the next page

The real fill failed at "diigo returned 44 items for page 167 of 168":
diigo's `total` overstates what load_user_items returns, so the true
last page looked short and the guard took it for a capped page size.

A short page that isn't the last by `total` now fetches the next page
(paced like any diigo call): empty means the data really ends there —
accepted, with a "total-overstated" notice logging total vs actual;
anything else means items would be skipped — refused, the message now
giving both counts. The fake gains an account whose total claims 60
more than it has; a fill on it runs to done.

Generated-by: Claude Opus 5.5

diigo-cache/tests/caches.test.ts

@@ -78,7 +78,7 @@ describe("page size", () => {
 			// settle the RPC promise ourselves: expect().rejects on a DO stub's
 			// promise leaves the rejection unhandled
 			const failure = () => stub.page(1, PAGE_SIZE).then(() => null, (e: unknown) => String(e));
-			expect(await failure()).toMatch(/returned 64 items for page 1 of 3 \(asked for 100\)/);
+			expect(await failure()).toMatch(/returned 64 items for page 1 of 3 \(asked for 100\), then 64 for page 2/);
 			expect(spy.mock.calls.map((c) => c[0]).filter((e) => e?.outcome === "short-page")).toHaveLength(1);
 			// nothing was stored: asking again refuses again
 			expect(await failure()).toMatch(/page size not honored/);
@@ -87,6 +87,21 @@ describe("page size", () => {
 		}
 	});
 
+	it("a short page whose next page is empty is the real end: diigo's total overstated, noted not refused", async () => {
+		const spy = vi.spyOn(console, "log");
+		try {
+			const stub = testEnv.CACHE_DO.get(testEnv.CACHE_DO.newUniqueId());
+			await stub.setup({ webappId: "fake-overstated-webapp" });
+			// 250 items claimed as 310: page 3 holds the last 50, "of 4"
+			const page = await stub.page(3, PAGE_SIZE);
+			expect(page.items).toHaveLength(50);
+			const notes = spy.mock.calls.map((c) => c[0]).filter((e) => e?.outcome === "total-overstated");
+			expect(notes).toEqual([expect.objectContaining({ page: 3, total: 310, actual: 250 })]);
+		} finally {
+			spy.mockRestore();
+		}
+	});
+
 	it("the last page may be short", async () => {
 		const stub = testEnv.CACHE_DO.get(testEnv.CACHE_DO.newUniqueId());
 		await stub.setup({ webappId: WEBAPP_ID });