fix: text compose papercuts (#270)

* make fixes

* cleanup

js/desktop/src/features/particles/text-particle-view.tsx

@@ -8,8 +8,11 @@ import {
   type LinkPreviewEntry,
 } from '@/hooks/use-link-metadata';
 import { extractUrls } from '@/lib/link-metadata';
+import { getImmersiveTextStyle } from '@/lib/immersive-text';
+import { hasMarkdownFormatting } from '@/lib/markdown';
 import {
   LinkPreviewCard,
+  LinkPreviewCardFallback,
   LinkPreviewCardSkeleton,
 } from '@/components/link-preview-card';
 import { useParticleAttachments } from '@/hooks/use-particle-attachments';
@@ -51,18 +54,6 @@ function computeReadDuration(
   return Math.min(Math.max(base + extra, MIN_DURATION_S), MAX_DURATION_S);
 }
 
-function getImmersiveTextStyle(length: number) {
-  if (length < 30) return { size: 'text-5xl', weight: 'font-semibold' };
-  if (length < 70) return { size: 'text-3xl', weight: 'font-semibold' };
-  return { size: 'text-2xl', weight: 'font-normal' };
-}
-
-function hasMarkdownFormatting(content: string): boolean {
-  return /^#{1,6} |^\s*[-*+] |^\s*\d+\. |^```|`[^`]+`|\*\*|__|\*[^*]|_[^_]|^>/m.test(
-    content,
-  );
-}
-
 function LinkPreviews({ entries }: { entries: LinkPreviewEntry[] }) {
   return (
     <div className="flex flex-wrap gap-3">
@@ -72,7 +63,9 @@ function LinkPreviews({ entries }: { entries: LinkPreviewEntry[] }) {
             <LinkPreviewCardSkeleton />
           ) : entry.metadata ? (
             <LinkPreviewCard metadata={entry.metadata} />
-          ) : null}
+          ) : (
+            <LinkPreviewCardFallback url={entry.url} />
+          )}
         </div>
       ))}
     </div>
@@ -209,17 +202,7 @@ export function TextParticleView({
   // Mode 3: card layout
   return (
     <div className="group relative flex h-full w-full items-center justify-center bg-gradient-to-b from-black/40 via-black/20 to-black/40 px-8 pt-[var(--stream-safe-top,2rem)] pb-[var(--stream-safe-bottom,2rem)]">
-      <div
-        className={cn(
-          'flex max-h-full w-full max-w-2xl flex-col gap-4 overflow-y-auto overscroll-contain rounded bg-white/10 p-6 backdrop-blur-md',
-          '[&::-webkit-scrollbar]:w-2',
-          '[&::-webkit-scrollbar]:p-2',
-          '[&::-webkit-scrollbar-track]:bg-transparent',
-          '[&::-webkit-scrollbar-thumb]:rounded-full',
-          '[&::-webkit-scrollbar-thumb]:bg-white/30',
-          '[&::-webkit-scrollbar-thumb]:hover:bg-white/50',
-        )}
-      >
+      <div className="scrollbar-card flex max-h-full w-full max-w-[calc(var(--message-content-width)_+_var(--message-card-padding)*2)] flex-col gap-4 overflow-y-auto overscroll-contain rounded bg-white/10 p-[var(--message-card-padding)] backdrop-blur-md">
         <MarkdownEditor
           key={content}
           value={content}