Use CommonMark plugin for @-mentions

app/CommonMark/Renderers/ContactMentionRenderer.php

@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\CommonMark\Renderers;
+
+use App\Models\Contact;
+use League\CommonMark\Node\Node;
+use League\CommonMark\Renderer\ChildNodeRendererInterface;
+use League\CommonMark\Renderer\NodeRendererInterface;
+
+class ContactMentionRenderer implements NodeRendererInterface
+{
+    public function render(Node $node, ChildNodeRendererInterface $childRenderer): string
+    {
+        $contact = Contact::where('nick', $node->getIdentifier())->first();
+
+        if ($contact === null) {
+            return '<a href="https://twitter.com/' . $node->getIdentifier() . '">@' . $node->getIdentifier() . '</a>';
+        }
+
+        return trim(view('templates.mini-hcard', ['contact' => $contact])->render());
+    }
+}