diigo-cache: public list shows each bookmark's date first

The list is in diigo's updated order; each item now leads with its
updated_at as Date#toISOString() (diigo sends epoch seconds; updatedISO
converts, tested), or "(no date)".

Generated-by: Claude Opus 5.5

diigo-cache/src/index.ts

@@ -15,7 +15,7 @@
 import { WorkerEntrypoint } from "cloudflare:workers";
 import { DiigoCache, PublicCache } from "./cache.js";
 import type { Item } from "./cache.js";
-import { usernameOf } from "./items.js";
+import { updatedISO, usernameOf } from "./items.js";
 import { toWebkey, idFromWebkey, isWebkey, shashKey } from "./webkeys.js";
 import { pmSave } from "./pm-save.js";
 
@@ -457,7 +457,9 @@ ${items
 		const title = typeof it.title === "string" && it.title ? it.title : url;
 		const desc = typeof it.description === "string" && it.description ? `<br><small>${esc(it.description)}</small>` : "";
 		const href = /^https?:\/\//i.test(url) ? url : "#";
-		return `<li><a href="${esc(href)}">${esc(title)}</a>${desc}</li>`;
+		const when = updatedISO(it);
+		const date = when ? `<time datetime="${when}">${when}</time>` : "(no date)";
+		return `<li>${date} <a href="${esc(href)}">${esc(title)}</a>${desc}</li>`;
 	})
 	.join("\n")}
 </ol>`;

diigo-cache/src/items.ts

@@ -64,3 +64,11 @@ export function usernameOf(item: Item | undefined): string {
 export function publicOnly(rows: ItemRow[]): ItemRow[] {
 	return rows.filter((r) => !r.private);
 }
+
+/** when diigo last updated the item, as `Date#toISOString()`, or "" when
+ * it carries no usable `updated_at` (diigo sends epoch *seconds*) */
+export function updatedISO(item: Item): string {
+	const secs = item.updated_at;
+	if (typeof secs !== "number" || !Number.isFinite(secs)) return "";
+	return new Date(secs * 1000).toISOString();
+}