v4: link previews are read once, in one place, and no longer take an error page, a relative image or a mask icon for the page's — each provider fetched its page and scanned it with regular expressions of its own, the generic one some fifteen times, and Bandcamp and SoundCloud read only OG tags. fetchPage (remote/fetch.ts) now fetches every page, follows redirects to the address it was served from, and refuses an error status, so a 404 or a bot challenge is unreachable rather than a preview titled "Just a moment...", and a refresh no longer overwrites good metadata with it. parsePage (remote/html.ts) reads it in one linear pass with a real attribute reader: unquoted values, a > inside quotes, og: tags under name as well as property, and nothing from comments or scripts. Every URL a page names is resolved against where it was served from, so a relative og:image works; entities are decoded in one pass, &eacute; and &rsquo; included, and one that names no character no longer fails the preview (bandcamp-tralbum.ts shares the decoder). The mask icon is no longer the favicon, JSON-LD prefers the page's node over the site's, tracking pixels and lazy placeholders aren't thumbnails, an og:url with a slug keeps the OG tags, and a <title> loses its site suffix. genericPreview is the base of the Bandcamp, SoundCloud and YouTube channel previews; SoundCloud takes www., m. and on.soundcloud.com short links, embedding the page they lead to, and Bandcamp keeps only its own player. The service tidies every preview: text on one line, titles and descriptions capped, only http(s) images and players. RichContent.type is now RichContentType, and the unused videoId is gone.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

api/test/services/rich-content-service.test.ts

@@ -41,3 +41,15 @@ Deno.test("tryFetchRichContent: an unreachable page is ok:false with a stub", as
     },
   });
 });
+
+Deno.test("tryFetchRichContent: an error page is unreachable, not a preview", async () => {
+  using net = stubNetwork(() => html(`<title>404 Not Found</title>`, 404));
+  const url = "https://example.com/gone";
+  assertEquals(await tryFetchRichContent(url), {
+    ok: false,
+    content: { type: "generic", url, siteName: "example.com" },
+  });
+  // Not kept: the page may be back next time.
+  await tryFetchRichContent(url);
+  assertEquals(net.calls.length, 2);
+});