diigo-cache: fetch 128 items per diigo page; refuse short pages

PAGE_SIZE = 128 (was 24), one constant for the fill job, public pages,
dumps, and DiigoBridge, so a cache never mixes sizes: ~131 pages instead
of ~698 for 16.7k bookmarks.

Cache invalidation, agreed beforehand: pages are cached by (page number,
size), so pages cached at 24 become misses and refetch at 128. Items are
keyed by link_id and just re-upsert; nothing is lost.

Unknown whether diigo honors count=128, so a short page that isn't the
last is refused loudly (logged, thrown; a fill fails with the reason)
rather than silently skipping items. The fake gains a capped account to
test it; the plain account grows to 300 (3 pages), the deep one to 6000.

Generated-by: Claude Opus 5.5

diigo-cache/tests/fake-webapp.js

@@ -1,14 +1,17 @@
 /**
  * @file a stand-in for webapp's `WebAppFactory` entrypoint, for tests: an
  * auxiliary worker (plain JS — the vitest pool doesn't transform aux
- * workers) serving diigo-shaped `load_user_items` pages. 30 items, every
- * third private; one webapp id is known. Counts its diigo calls so tests
+ * workers) serving diigo-shaped `load_user_items` pages. 300 items (3
+ * pages of 128), every third private; a few webapp ids are known. Counts its diigo calls so tests
  * can tell a cache hit (no call) from a miss.
  */
 import { RpcTarget, WorkerEntrypoint } from "cloudflare:workers";
 
 const KNOWN_WEBAPP = "fake-webapp-id";
-const TOTAL = 30;
+const TOTAL = 300;
+/** the plain account, but diigo-style capped at 100 items per page */
+const CAPPED_WEBAPP = "fake-capped-webapp";
+const CAP = 100;
 
 /** a second account, for date filters (goal 1d): 60 bookmarks, item n
  * updated n-1 days + 1 hour before the call, in diigo's updated-desc
@@ -16,9 +19,9 @@ const TOTAL = 30;
  * 5th an old bookmark edited recently (created 100 days before updated) */
 const DATED_WEBAPP = "fake-dated-webapp";
 const DATED_TOTAL = 60;
-/** the same shape, 1200 deep (~3.3 years, 50 pages): for walk cost */
+/** the same shape, 6000 deep (~16 years, 47 pages of 128): for walk cost */
 const DEEP_WEBAPP = "fake-deep-webapp";
-const DEEP_TOTAL = 1200;
+const DEEP_TOTAL = 6000;
 const HOUR = 60 * 60 * 1000;
 
 function datedItem(n, now, user = "dated_dan") {
@@ -38,11 +41,11 @@ function datedItem(n, now, user = "dated_dan") {
 
 /** item n (1-based, in diigo's order): diigo's field names, made-up
  * values. link_id and updated_at are scrambled (distinct; 7 and 11 are
- * coprime to 31), so neither column sorts back into diigo's order — a
+ * coprime to 307, a prime above TOTAL), so neither column sorts back into diigo's order — a
  * cache that replays by column rather than by fetch order is caught. */
 function item(n) {
 	return {
-		link_id: 1000 + ((n * 7) % 31),
+		link_id: 1000 + ((n * 7) % 307),
 		url: `https://example.com/${n}`,
 		title: `bookmark ${n}`,
 		description: "",
@@ -52,7 +55,7 @@ function item(n) {
 		user_id: 4242,
 		tags: "",
 		created_at: 1700000000,
-		updated_at: 1700001000 + ((n * 11) % 31),
+		updated_at: 1700001000 + ((n * 11) % 307),
 	};
 }
 
@@ -61,7 +64,7 @@ let calls = 0;
 class FakeGet extends RpcTarget {
 	#path;
 	#params;
-	/** null (the plain account), "dated", or "deep" */
+	/** null (the plain account), "capped", "dated", or "deep" */
 	#dated;
 	constructor(path, params, dated) {
 		super();
@@ -78,13 +81,14 @@ class FakeGet extends RpcTarget {
 	async get() {
 		calls += 1;
 		if (this.#path !== "load_user_items") throw new Error(`fake webapp: no route ${this.#path}`);
-		const count = Number(this.#params.count);
+		const count = Math.min(Number(this.#params.count), this.#dated === "capped" ? CAP : Infinity);
 		const page = Number(this.#params.page_num);
-		const total = this.#dated === "deep" ? DEEP_TOTAL : this.#dated ? DATED_TOTAL : TOTAL;
+		const dated = this.#dated === "dated" || this.#dated === "deep";
+		const total = this.#dated === "deep" ? DEEP_TOTAL : dated ? DATED_TOTAL : TOTAL;
 		const now = Date.now();
 		const items = [];
 		for (let n = (page - 1) * count + 1; n <= Math.min(page * count, total); n += 1) {
-			items.push(this.#dated ? datedItem(n, now, this.#dated === "deep" ? "deep_dee" : "dated_dan") : item(n));
+			items.push(dated ? datedItem(n, now, this.#dated === "deep" ? "deep_dee" : "dated_dan") : item(n));
 		}
 		return JSON.stringify({ total, items });
 	}
@@ -92,7 +96,7 @@ class FakeGet extends RpcTarget {
 
 export class WebAppFactory extends WorkerEntrypoint {
 	async at(id) {
-		const kind = { [KNOWN_WEBAPP]: null, [DATED_WEBAPP]: "dated", [DEEP_WEBAPP]: "deep" }[id];
+		const kind = { [KNOWN_WEBAPP]: null, [CAPPED_WEBAPP]: "capped", [DATED_WEBAPP]: "dated", [DEEP_WEBAPP]: "deep" }[id];
 		if (kind === undefined) throw new Error("fake webapp: unknown id");
 		return new FakeGet("", {}, kind);
 	}