feat: support markdown

package.json

@@ -65,9 +65,12 @@
     "react-day-picker": "^8.10.1",
     "react-dom": "^18.3.1",
     "react-hook-form": "^7.53.0",
+    "react-markdown": "^10.1.0",
     "react-resizable-panels": "^2.1.3",
     "react-router-dom": "^6.26.2",
     "recharts": "^2.12.7",
+    "rehype-sanitize": "^6.0.0",
+    "remark-gfm": "^4.0.1",
     "sonner": "^1.5.0",
     "tailwind-merge": "^2.5.2",
     "tailwindcss-animate": "^1.0.7",
@@ -79,7 +82,7 @@
   },
   "devDependencies": {
     "@eslint/js": "^9.9.0",
-    "@tailwindcss/typography": "^0.5.15",
+    "@tailwindcss/typography": "^0.5.16",
     "@testing-library/jest-dom": "^6.6.3",
     "@testing-library/react": "^16.3.0",
     "@testing-library/user-event": "^14.6.1",

src/components/CommentCard.tsx

@@ -11,7 +11,7 @@ import {
 import { Button } from '@/components/ui/button';
 import { BookmarkButton } from '@/components/ui/bookmark-button';
 import { AuthorDisplay } from '@/components/ui/author-display';
-import { LinkRenderer } from '@/components/ui/link-renderer';
+import { MarkdownRenderer } from '@/components/ui/markdown-renderer';
 import { usePending, usePendingVote } from '@/hooks/usePending';
 import {
   Tooltip,
@@ -146,9 +146,9 @@ const CommentCard: React.FC<CommentCardProps> = ({
             </div>
           </div>
 
-          <p className="text-sm break-words mb-2">
-            <LinkRenderer text={comment.content} />
-          </p>
+          <div className="text-sm break-words mb-2 prose prose-invert max-w-none">
+            <MarkdownRenderer content={comment.content} />
+          </div>
 
           <div className="flex items-center gap-2">
             {canModerate && !comment.moderated && (

src/components/PostDetail.tsx

@@ -10,7 +10,8 @@ import {
 } from '@/hooks';
 import { Button } from '@/components/ui/button';
 //
-import ResizableTextarea from '@/components/ui/resizable-textarea';
+// import ResizableTextarea from '@/components/ui/resizable-textarea';
+import { MarkdownInput } from '@/components/ui/markdown-input';
 import {
   ArrowLeft,
   ArrowUp,
@@ -25,7 +26,7 @@ import { formatDistanceToNow } from 'date-fns';
 import { RelevanceIndicator } from './ui/relevance-indicator';
 import { AuthorDisplay } from './ui/author-display';
 import { BookmarkButton } from './ui/bookmark-button';
-import { LinkRenderer } from './ui/link-renderer';
+import { MarkdownRenderer } from './ui/markdown-renderer';
 import CommentCard from './CommentCard';
 import { usePending, usePendingVote } from '@/hooks/usePending';
 import { ShareButton } from './ui/ShareButton';
@@ -263,9 +264,9 @@ const PostDetail = () => {
                   title={post.title}
                 />
               </div>
-              <p className="text-sm whitespace-pre-wrap break-words">
-                <LinkRenderer text={post.content} />
-              </p>
+              <div className="text-sm break-words prose prose-invert max-w-none">
+                <MarkdownRenderer content={post.content} />
+              </div>
             </div>
           </div>
         </div>
@@ -279,20 +280,15 @@ const PostDetail = () => {
               <MessageCircle className="w-4 h-4" />
               Add a comment
             </h2>
-            <ResizableTextarea
+            <MarkdownInput
               placeholder="What are your thoughts?"
               value={newComment}
-              onChange={e => setNewComment(e.target.value)}
-              className="bg-cyber-muted/50 border-cyber-muted"
+              onChange={setNewComment}
               disabled={isCreatingComment}
               minHeight={100}
               initialHeight={140}
               maxHeight={600}
             />
-            <div className="flex items-center justify-between text-xs text-muted-foreground mt-1 mb-2">
-              <span>Press Enter for newline • Ctrl+Enter or Shift+Enter to send</span>
-              <span />
-            </div>
             <div className="flex justify-end">
               <Button
                 type="submit"

src/components/ui/markdown-input.tsx

@@ -0,0 +1,75 @@
+import React from 'react';
+import ResizableTextarea from '@/components/ui/resizable-textarea';
+import { Tabs, TabsContent, TabsList, TabsTrigger } from '@/components/ui/tabs';
+import { MarkdownRenderer } from './markdown-renderer';
+
+interface MarkdownInputProps {
+  value: string;
+  onChange: (value: string) => void;
+  placeholder?: string;
+  disabled?: boolean;
+  className?: string;
+  minHeight?: number;
+  initialHeight?: number;
+  maxHeight?: number;
+}
+
+/**
+ * Textarea with Markdown preview tabs.
+ */
+export const MarkdownInput: React.FC<MarkdownInputProps> = ({
+  value,
+  onChange,
+  placeholder,
+  disabled,
+  className,
+  minHeight,
+  initialHeight,
+  maxHeight,
+}) => {
+  const [tab, setTab] = React.useState<'write' | 'preview'>('write');
+
+  return (
+    <div className={className}>
+      <Tabs value={tab} onValueChange={v => setTab(v as 'write' | 'preview')}>
+        <TabsList className="mb-2">
+          <TabsTrigger value="write">Write</TabsTrigger>
+          <TabsTrigger value="preview">Preview</TabsTrigger>
+        </TabsList>
+
+        <TabsContent value="write">
+          <ResizableTextarea
+            placeholder={placeholder}
+            value={value}
+            onChange={e => onChange(e.target.value)}
+            className="bg-cyber-muted/50 border-cyber-muted"
+            disabled={disabled}
+            minHeight={minHeight}
+            initialHeight={initialHeight}
+            maxHeight={maxHeight}
+          />
+          <div className="flex items-center justify-between text-xs text-muted-foreground mt-1 mb-2">
+            <span>Markdown supported • Ctrl+Enter or Shift+Enter to send</span>
+            <button
+              type="button"
+              className="underline hover:opacity-80"
+              onClick={() => setTab('preview')}
+            >
+              Preview
+            </button>
+          </div>
+        </TabsContent>
+
+        <TabsContent value="preview">
+          <div className="p-3 border rounded-sm bg-card">
+            <MarkdownRenderer content={value} className="prose prose-invert max-w-none" />
+          </div>
+        </TabsContent>
+      </Tabs>
+    </div>
+  );
+};
+
+export default MarkdownInput;
+
+

src/components/ui/markdown-renderer.tsx

@@ -0,0 +1,77 @@
+import React from 'react';
+import ReactMarkdown from 'react-markdown';
+import remarkGfm from 'remark-gfm';
+import rehypeSanitize, { defaultSchema } from 'rehype-sanitize';
+
+interface MarkdownRendererProps {
+  content: string;
+  className?: string;
+}
+
+/**
+ * Renders sanitized Markdown with GFM support.
+ */
+export const MarkdownRenderer: React.FC<MarkdownRendererProps> = ({ content, className }) => {
+  // Extend sanitize schema to allow common markdown elements (headings, lists, code, tables, etc.)
+  const schema: any = {
+    ...defaultSchema,
+    tagNames: [
+      ...(defaultSchema.tagNames || []),
+      'h1',
+      'h2',
+      'h3',
+      'h4',
+      'h5',
+      'h6',
+      'p',
+      'ul',
+      'ol',
+      'li',
+      'strong',
+      'em',
+      'del',
+      'blockquote',
+      'hr',
+      'code',
+      'pre',
+      'table',
+      'thead',
+      'tbody',
+      'tr',
+      'th',
+      'td',
+      'a',
+      'img',
+    ],
+    attributes: {
+      ...defaultSchema.attributes,
+      a: [
+        ...(defaultSchema.attributes?.a || []),
+        ['href'],
+        ['target'],
+        ['rel'],
+      ],
+      img: [
+        ...(defaultSchema.attributes?.img || []),
+        ['src'],
+        ['alt'],
+        ['title'],
+      ],
+      code: [
+        ...(defaultSchema.attributes?.code || []),
+        ['className'],
+      ],
+    },
+  };
+  return (
+    <div className={className}>
+      <ReactMarkdown remarkPlugins={[remarkGfm]} rehypePlugins={[[rehypeSanitize, schema]]}>
+        {content || ''}
+      </ReactMarkdown>
+    </div>
+  );
+};
+
+export default MarkdownRenderer;
+
+

tailwind.config.ts

@@ -1,5 +1,6 @@
 import type { Config } from 'tailwindcss';
 import tailwindcssAnimate from 'tailwindcss-animate';
+import typography from '@tailwindcss/typography';
 
 export default {
   darkMode: ['class'],
@@ -117,5 +118,5 @@ export default {
       },
     },
   },
-  plugins: [tailwindcssAnimate],
+  plugins: [tailwindcssAnimate, typography],
 } satisfies Config;