diigo-cache: invalidate the last N days of cached pages

invalidateRecent(days) drops the cached pages holding anything diigo
updated within the last N days (on the cache's injected clock), and
every page before them, so the next read or fill refetches them; item
rows stay. Exposed on the fill capability (private and public) and on
the webkey page as "invalidate the last N days" per cache.

A user-requested refetch, not a change in what stored state means.

Generated-by: Claude Opus 5.5

diigo-cache/src/cache.ts

@@ -245,6 +245,37 @@ abstract class PagedCache extends DurableObject<CacheEnv> {
 		return stopped;
 	}
 
+	/**
+	 * drop the cached pages holding anything diigo updated in the last
+	 * `days` days, and every page before them (newer still; and new
+	 * updates push items back), so the next read or fill refetches them.
+	 * Item rows stay. Returns how many pages were dropped.
+	 */
+	async invalidateRecent(days: number): Promise<{ pages: number }> {
+		if (!Number.isInteger(days) || days < 1 || days > 3650) throw new Error("days: expected a whole number from 1 to 3650");
+		this.#schema();
+		const cutoff = Math.floor(this.#clock.now() / 1000) - days * 24 * 60 * 60;
+		const sql = this.ctx.storage.sql;
+		const deepest = sql
+			.exec<{ last: number | null }>(
+				"select max(page_members.page_num) as last from page_members join items on items.item_id = page_members.item_id where cast(items.updated as integer) >= ?",
+				cutoff,
+			)
+			.toArray()[0]?.last;
+		if (!deepest) {
+			console.log({ event: "cache", kind: this.kind, outcome: "invalidated", days, pages: 0 });
+			return { pages: 0 };
+		}
+		let pages = 0;
+		this.ctx.storage.transactionSync(() => {
+			pages = Number(sql.exec<{ n: number }>("select count(*) as n from pages where page_num <= ?", deepest).toArray()[0].n);
+			sql.exec("delete from page_members where page_num <= ?", deepest);
+			sql.exec("delete from pages where page_num <= ?", deepest);
+		});
+		console.log({ event: "cache", kind: this.kind, outcome: "invalidated", days, pages });
+		return { pages };
+	}
+
 	/** one fill step: up to `fillStep` pages, progress saved after each,
 	 * then the next step is scheduled (or the job ends) */
 	async alarm(): Promise<void> {