feat(embeds): fallback for hung embeds and deleted X posts (#200)

Probed how real providers fail before picking signals:
- X renders an EMPTY frame for a deleted/private/suspended post and says
  so only via postMessage `twttr.private.no_results`. The post embed now
  swaps to "This post isn't available…" with an "Open on X" link.
- A hung frame never fires `load`. After 20 s every player (media, rich
  posts, TikTok, Steam widget, X) overlays "This embed is taking too long
  to load" with Retry (remounts the iframe) and "Open on <site>". A late
  `load` clears it.
- Instagram and Bluesky show their own "removed / not found" page, and a
  refused request still fires `load` (browser error page), so neither needs
  or can use a guess. A missing height message is not treated as failure.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/app/components/url-preview/UrlPreview.css.tsx

@@ -315,6 +315,33 @@ export const EmbedIframeStatic = style([
   },
 ]);
 
+// Shown over (or instead of) an embed that hung or that the provider says is gone.
+export const EmbedNotice = style([
+  DefaultReset,
+  {
+    position: 'absolute',
+    inset: 0,
+    display: 'flex',
+    flexDirection: 'column',
+    alignItems: 'center',
+    justifyContent: 'center',
+    gap: config.space.S200,
+    padding: config.space.S300,
+    textAlign: 'center',
+    backgroundColor: color.Surface.Container,
+    color: color.Surface.OnContainer,
+  },
+]);
+
+export const EmbedNoticeStatic = style([
+  EmbedNotice,
+  {
+    position: 'static',
+    minHeight: toRem(120),
+    borderRadius: config.radii.R300,
+  },
+]);
+
 export const EmbedPlaceholder = style([
   DefaultReset,
   {

src/app/components/url-preview/UrlPreviewCard.tsx

@@ -34,11 +34,13 @@ import { onEnterOrSpace } from '../../utils/keyboard';
 import { useSetting } from '../../state/hooks/settings';
 import { settingsAtom } from '../../state/settings';
 import {
+  EMBED_LOAD_TIMEOUT_MS,
   extractEmbedHeight,
   getSteamTarget,
   getTikTokVideoId,
   getTweetId,
   isTikTokLink,
+  isTwitterNoResults,
   MediaEmbed,
   parseMediaEmbed,
   steamWidgetEmbedUrl,
@@ -669,10 +671,84 @@ function useIframeAutoHeight(origins: string[], initial: number) {
   return { ref, height };
 }
 
+// Embed iframes that never fire `load` (provider down, network stall) would
+// otherwise sit as an empty box forever. After EMBED_LOAD_TIMEOUT_MS the card
+// offers Retry / "Open on …"; a late `load` clears the notice on its own.
+// `attempt` is the iframe's `key`, so Retry remounts it.
+function useEmbedWatchdog(active: boolean) {
+  const [attempt, setAttempt] = useState(0);
+  const [loaded, setLoaded] = useState(false);
+  const [timedOut, setTimedOut] = useState(false);
+  useEffect(() => {
+    setLoaded(false);
+    setTimedOut(false);
+    if (!active) return undefined;
+    const t = window.setTimeout(() => setTimedOut(true), EMBED_LOAD_TIMEOUT_MS);
+    return () => window.clearTimeout(t);
+  }, [active, attempt]);
+  const onLoad = useCallback(() => setLoaded(true), []);
+  const retry = useCallback(() => setAttempt((a) => a + 1), []);
+  return { attempt, onLoad, stalled: active && timedOut && !loaded, retry };
+}
+
+function EmbedNotice({
+  message,
+  url,
+  site,
+  onRetry,
+  inFlow,
+}: {
+  message: string;
+  url: string;
+  site: string;
+  onRetry?: () => void;
+  /** Render in the layout flow instead of as an overlay on the player box. */
+  inFlow?: boolean;
+}) {
+  return (
+    <div className={inFlow ? previewCss.EmbedNoticeStatic : previewCss.EmbedNotice} role="status">
+      <Text size="T300">{message}</Text>
+      <Box gap="200" wrap="Wrap" justifyContent="Center">
+        {onRetry && (
+          <Chip variant="Secondary" radii="Pill" className={MobileTouchTarget} onClick={onRetry}>
+            <Text size="T200">Retry</Text>
+          </Chip>
+        )}
+        <Chip
+          as="a"
+          href={url}
+          target="_blank"
+          rel="noreferrer"
+          variant="Primary"
+          radii="Pill"
+          className={MobileTouchTarget}
+        >
+          <Text size="T200">Open on {site}</Text>
+        </Chip>
+      </Box>
+    </div>
+  );
+}
+
+const EMBED_STALLED_MESSAGE = 'This embed is taking too long to load.';
+
 // Interactive X/Twitter post embed — playable video/GIF, galleries, quote tweets.
 // Self-sizes via useIframeAutoHeight. Only mounted after "View post" (facade).
-function TweetEmbed({ id }: { id: string }) {
+function TweetEmbed({ id, url }: { id: string; url: string }) {
   const { ref, height } = useIframeAutoHeight(TWITTER_ORIGINS, 320);
+  const { attempt, onLoad, stalled, retry } = useEmbedWatchdog(true);
+  // A deleted/private/suspended post renders an EMPTY frame; X only says so
+  // via `twttr.private.no_results`.
+  const [unavailable, setUnavailable] = useState(false);
+  useEffect(() => {
+    const onMessage = (e: MessageEvent) => {
+      if (!TWITTER_ORIGINS.includes(e.origin)) return;
+      if (!ref.current || e.source !== ref.current.contentWindow) return;
+      if (isTwitterNoResults(e.data)) setUnavailable(true);
+    };
+    window.addEventListener('message', onMessage);
+    return () => window.removeEventListener('message', onMessage);
+  }, [ref]);
   const theme =
     typeof window !== 'undefined' &&
     window.matchMedia &&
@@ -680,20 +756,38 @@ function TweetEmbed({ id }: { id: string }) {
       ? 'light'
       : 'dark';
 
+  if (unavailable) {
+    return (
+      <EmbedNotice
+        inFlow
+        message="This post isn't available. It may have been deleted, or the account is private or suspended."
+        url={url}
+        site="X"
+      />
+    );
+  }
+
   return (
-    <iframe
-      ref={ref}
-      className={previewCss.EmbedIframeStatic}
-      src={`https://platform.twitter.com/embed/Tweet.html?id=${encodeURIComponent(
-        id,
-      )}&theme=${theme}&dnt=true`}
-      title="Post on X"
-      style={{ height: `${height}px` }}
-      sandbox={EMBED_SANDBOX}
-      allow="autoplay; encrypted-media; picture-in-picture; fullscreen"
-      loading="lazy"
-      scrolling="no"
-    />
+    <div style={{ position: 'relative' }}>
+      <iframe
+        key={attempt}
+        ref={ref}
+        className={previewCss.EmbedIframeStatic}
+        src={`https://platform.twitter.com/embed/Tweet.html?id=${encodeURIComponent(
+          id,
+        )}&theme=${theme}&dnt=true`}
+        title="Post on X"
+        style={{ height: `${height}px` }}
+        sandbox={EMBED_SANDBOX}
+        allow="autoplay; encrypted-media; picture-in-picture; fullscreen"
+        loading="lazy"
+        scrolling="no"
+        onLoad={onLoad}
+      />
+      {stalled && (
+        <EmbedNotice message={EMBED_STALLED_MESSAGE} url={url} site="X" onRetry={retry} />
+      )}
+    </div>
   );
 }
 
@@ -773,7 +867,7 @@ function TwitterCard({
           </IconButton>
         </div>
         <UrlPreviewContent>
-          <TweetEmbed id={tweetId} />
+          <TweetEmbed id={tweetId} url={url} />
         </UrlPreviewContent>
       </>
     );
@@ -1151,6 +1245,7 @@ function MediaEmbedCard({
   const [inlineMediaEmbeds] = useSetting(settingsAtom, 'inlineMediaEmbeds');
   const [playing, setPlaying] = useState(false);
   const mediaRef = useRef<HTMLDivElement>(null);
+  const { attempt, onLoad, stalled, retry } = useEmbedWatchdog(playing);
 
   const rawTitle = prev['og:title'] ?? '';
   const rawDescription = prev['og:description'] ?? '';
@@ -1228,30 +1323,54 @@ function MediaEmbedCard({
     <Box direction="Column" style={{ width: '100%', minWidth: 0 }}>
       {playing && rich ? (
         // Rich post embeds (Instagram/Reddit) are variable-height and self-size.
-        <iframe
-          ref={resizeRef}
-          className={previewCss.EmbedIframeStatic}
-          src={embed.embedUrl}
-          title={title || badge.label}
-          style={{ height: `${resizeHeight}px` }}
-          allow="autoplay; encrypted-media; picture-in-picture; fullscreen; clipboard-write"
-          sandbox={EMBED_SANDBOX}
-          allowFullScreen
-          loading="lazy"
-          scrolling="no"
-        />
+        <div style={{ position: 'relative' }}>
+          <iframe
+            key={attempt}
+            ref={resizeRef}
+            className={previewCss.EmbedIframeStatic}
+            src={embed.embedUrl}
+            title={title || badge.label}
+            style={{ height: `${resizeHeight}px` }}
+            allow="autoplay; encrypted-media; picture-in-picture; fullscreen; clipboard-write"
+            sandbox={EMBED_SANDBOX}
+            allowFullScreen
+            loading="lazy"
+            scrolling="no"
+            onLoad={onLoad}
+          />
+          {stalled && (
+            <EmbedNotice
+              message={EMBED_STALLED_MESSAGE}
+              url={url}
+              site={badge.label}
+              onRetry={retry}
+            />
+          )}
+        </div>
       ) : (
         <div ref={mediaRef} className={mediaClass} style={mediaStyle}>
           {playing ? (
-            <iframe
-              className={previewCss.EmbedIframe}
-              src={embed.embedUrl}
-              title={title || badge.label}
-              allow="autoplay; encrypted-media; picture-in-picture; fullscreen; clipboard-write"
-              sandbox={EMBED_SANDBOX}
-              allowFullScreen
-              loading="lazy"
-            />
+            <>
+              <iframe
+                key={attempt}
+                className={previewCss.EmbedIframe}
+                src={embed.embedUrl}
+                title={title || badge.label}
+                allow="autoplay; encrypted-media; picture-in-picture; fullscreen; clipboard-write"
+                sandbox={EMBED_SANDBOX}
+                allowFullScreen
+                loading="lazy"
+                onLoad={onLoad}
+              />
+              {stalled && (
+                <EmbedNotice
+                  message={EMBED_STALLED_MESSAGE}
+                  url={url}
+                  site={badge.label}
+                  onRetry={retry}
+                />
+              )}
+            </>
           ) : inlineMediaEmbeds ? (
             <button
               type="button"
@@ -1347,6 +1466,7 @@ function TikTokEmbedCard({ url, prev }: { url: string; prev: IPreviewUrlResponse
   const [failed, setFailed] = useState(false);
   const mediaRef = useRef<HTMLDivElement>(null);
   const abortRef = useRef<AbortController | null>(null);
+  const tiktokWatch = useEmbedWatchdog(playing && !!videoId);
 
   // Abort an in-flight oEmbed resolve if the card unmounts (scrolled away).
   useEffect(() => () => abortRef.current?.abort(), []);
@@ -1407,15 +1527,27 @@ function TikTokEmbedCard({ url, prev }: { url: string; prev: IPreviewUrlResponse
     <Box direction="Column" style={{ width: '100%', minWidth: 0 }}>
       <div ref={mediaRef} className={previewCss.EmbedMediaPortrait}>
         {playing && videoId ? (
-          <iframe
-            className={previewCss.EmbedIframe}
-            src={tiktokPlayerEmbedUrl(videoId)}
-            title={title || 'TikTok'}
-            allow="autoplay; encrypted-media; picture-in-picture; fullscreen; clipboard-write"
-            sandbox={EMBED_SANDBOX}
-            allowFullScreen
-            loading="lazy"
-          />
+          <>
+            <iframe
+              key={tiktokWatch.attempt}
+              className={previewCss.EmbedIframe}
+              src={tiktokPlayerEmbedUrl(videoId)}
+              title={title || 'TikTok'}
+              allow="autoplay; encrypted-media; picture-in-picture; fullscreen; clipboard-write"
+              sandbox={EMBED_SANDBOX}
+              allowFullScreen
+              loading="lazy"
+              onLoad={tiktokWatch.onLoad}
+            />
+            {tiktokWatch.stalled && (
+              <EmbedNotice
+                message={EMBED_STALLED_MESSAGE}
+                url={url}
+                site="TikTok"
+                onRetry={tiktokWatch.retry}
+              />
+            )}
+          </>
         ) : inlineMediaEmbeds ? (
           <button
             type="button"
@@ -1758,6 +1890,7 @@ function SteamAppCard({
   const useAuthentication = useMediaAuthentication();
   const [inlineMediaEmbeds] = useSetting(settingsAtom, 'inlineMediaEmbeds');
   const [showWidget, setShowWidget] = useState(false);
+  const steamWatch = useEmbedWatchdog(showWidget);
   const title = prev['og:title'] ?? '';
   const description = prev['og:description'] ?? '';
   const mxcImage = prev['og:image'] as string | undefined;
@@ -1791,13 +1924,25 @@ function SteamAppCard({
           </Text>
         )}
         {showWidget ? (
-          <iframe
-            className={previewCss.SteamWidget}
-            src={steamWidgetEmbedUrl(appId)}
-            title={title ? `Steam store: ${title}` : 'Steam store widget'}
-            sandbox={EMBED_SANDBOX}
-            loading="lazy"
-          />
+          <div style={{ position: 'relative' }}>
+            <iframe
+              key={steamWatch.attempt}
+              className={previewCss.SteamWidget}
+              src={steamWidgetEmbedUrl(appId)}
+              title={title ? `Steam store: ${title}` : 'Steam store widget'}
+              sandbox={EMBED_SANDBOX}
+              loading="lazy"
+              onLoad={steamWatch.onLoad}
+            />
+            {steamWatch.stalled && (
+              <EmbedNotice
+                message={EMBED_STALLED_MESSAGE}
+                url={url}
+                site="Steam"
+                onRetry={steamWatch.retry}
+              />
+            )}
+          </div>
         ) : (
           <Box alignItems="Center" gap="200" justifyContent="SpaceBetween">
             <Text

src/app/utils/videoEmbed.test.ts

@@ -32,6 +32,7 @@ import {
   buildVideoEmbedUrl,
   spotifyEmbedHeight,
   parseMediaEmbed,
+  isTwitterNoResults,
 } from './videoEmbed';
 
 const HOST = 'chat.lotusguild.org';
@@ -403,3 +404,28 @@ test('parseMediaEmbed: Twitch embed carries the parent host', () => {
   const clip = parseMediaEmbed('https://clips.twitch.tv/Slug', HOST);
   assert.ok(clip?.embedUrl.startsWith('https://clips.twitch.tv/embed?clip=Slug'));
 });
+
+test('isTwitterNoResults: detects X reporting a missing post (string or parsed)', () => {
+  // Captured from platform.twitter.com/embed/Tweet.html?id=1 (no such post).
+  const msg = {
+    'twttr.embed': {
+      jsonrpc: '2.0',
+      method: 'twttr.private.no_results',
+      id: 'embed-0',
+      params: [{ data: { tweet_id: '1' } }],
+    },
+  };
+  assert.equal(isTwitterNoResults(msg), true);
+  assert.equal(isTwitterNoResults(JSON.stringify(msg)), true);
+  assert.equal(isTwitterNoResults({ 'twttr.embed': [msg['twttr.embed']] }), true);
+});
+
+test('isTwitterNoResults: ignores normal embed traffic and junk', () => {
+  const call = (method: string) => ({ 'twttr.embed': { jsonrpc: '2.0', method, params: [] } });
+  assert.equal(isTwitterNoResults(call('twttr.private.initialized')), false);
+  assert.equal(isTwitterNoResults(call('twttr.private.resize')), false);
+  assert.equal(isTwitterNoResults(call('twttr.private.rendered')), false);
+  assert.equal(isTwitterNoResults('not json'), false);
+  assert.equal(isTwitterNoResults(null), false);
+  assert.equal(isTwitterNoResults({ type: 'MEASURE' }), false);
+});

src/app/utils/videoEmbed.ts

@@ -168,6 +168,33 @@ export function extractEmbedHeight(data: unknown): number | undefined {
   return undefined;
 }
 
+// How long an embed iframe may take to fire `load` before the card offers
+// Retry / "Open on …". Only a hang trips it: a frame whose request was refused,
+// or whose provider shows its own error page, still fires `load`.
+export const EMBED_LOAD_TIMEOUT_MS = 20_000;
+
+/**
+ * X's post embed (platform.twitter.com/embed/Tweet.html) renders an empty frame
+ * for a deleted, private or suspended post and reports it only via this
+ * postMessage: `{"twttr.embed": {"method": "twttr.private.no_results"}}`.
+ * `data` may be the raw string or the parsed object.
+ */
+export function isTwitterNoResults(data: unknown): boolean {
+  let d = data;
+  if (typeof d === 'string') {
+    try {
+      d = JSON.parse(d);
+    } catch {
+      return false;
+    }
+  }
+  if (!d || typeof d !== 'object') return false;
+  const tw = (d as { 'twttr.embed'?: unknown })['twttr.embed'];
+  if (!tw) return false;
+  const calls = (Array.isArray(tw) ? tw : [tw]) as Array<{ method?: string }>;
+  return calls.some((c) => c?.method === 'twttr.private.no_results');
+}
+
 export function tiktokPlayerEmbedUrl(id: string): string {
   // Pure 9:16 video player. music_info/description default OFF (they'd switch
   // TikTok to a wide "video + info panel" layout); controls/progress/play/volume/