diigo-cache: test that a cached page replays fetch-time order

A hit must replay diigo's order as fetched (page_members.pos), not a
column sort. The fake webapp's link_id and updated_at are scrambled so
neither column sorts back into diigo's order; ordering the replay by
updated or item_id fails the new test.

Generated-by: Claude Opus 5.5

diigo-cache/tests/caches.test.ts

@@ -79,6 +79,23 @@ describe("DiigoCache", () => {
 	});
 });
 
+describe("page replay order", () => {
+	it("a hit replays diigo's fetch-time order (page_members), not a column sort", async () => {
+		const stub = testEnv.CACHE_DO.get(testEnv.CACHE_DO.newUniqueId());
+		await stub.setup({ webappId: WEBAPP_ID });
+		const titles = (items: string[]) => parse(items).map((i) => i.title);
+		const expected = Array.from({ length: 24 }, (_, k) => `bookmark ${k + 1}`);
+
+		const miss = await stub.page(1, 24);
+		expect(titles(miss.items)).toEqual(expected);
+		// page 2's etch upserts other rows; page 1's replay must not shift
+		await stub.page(2, 24);
+		const hit = await stub.page(1, 24);
+		expect(hit.cached).toBe(true);
+		expect(titles(hit.items)).toEqual(expected);
+	});
+});
+
 describe("worker routes", () => {
 	const call = (path: string, init?: RequestInit) =>
 		worker.fetch(new Request(`https://diigo-cache.test${path}`, init), env as never);