diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 407be2a..c8cc210 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -13,6 +13,9 @@ jobs:
       - uses: actions/checkout@v4
       - uses: oven-sh/setup-bun@v2
       - run: bun install --frozen-lockfile
+      - name: Dependency vulnerability scan
+        run: bun audit
+        continue-on-error: true
       - run: bun run type-check
       - run: bun run lint
       - run: bun run test
diff --git a/next.config.ts b/next.config.ts
index eec398f..40fed3a 100644
--- a/next.config.ts
+++ b/next.config.ts
@@ -1,5 +1,34 @@
 import type { NextConfig } from "next";
 
+const securityHeaders = [
+  { key: "X-DNS-Prefetch-Control", value: "on" },
+  {
+    key: "Strict-Transport-Security",
+    value: "max-age=63072000; includeSubDomains; preload",
+  },
+  { key: "X-Frame-Options", value: "DENY" },
+  { key: "X-Content-Type-Options", value: "nosniff" },
+  { key: "Referrer-Policy", value: "strict-origin-when-cross-origin" },
+  {
+    key: "Permissions-Policy",
+    value: "camera=(), microphone=(), geolocation=(), browsing-topics=()",
+  },
+  {
+    key: "Content-Security-Policy",
+    value: [
+      "default-src 'self'",
+      "script-src 'self' 'unsafe-inline'",
+      "style-src 'self' 'unsafe-inline'",
+      "img-src 'self' data: https:",
+      "font-src 'self' https://fonts.gstatic.com",
+      "connect-src 'self'",
+      "frame-ancestors 'none'",
+      "base-uri 'self'",
+      "form-action 'self'",
+    ].join("; "),
+  },
+];
+
 const nextConfig: NextConfig = {
   experimental: {
     serverActions: {
@@ -14,6 +43,14 @@ const nextConfig: NextConfig = {
       },
     ],
   },
+  async headers() {
+    return [
+      {
+        source: "/(.*)",
+        headers: securityHeaders,
+      },
+    ];
+  },
 };
 
 export default nextConfig;
diff --git a/src/app/blog/[slug]/page.tsx b/src/app/blog/[slug]/page.tsx
index 3b2192c..9b235a0 100644
--- a/src/app/blog/[slug]/page.tsx
+++ b/src/app/blog/[slug]/page.tsx
@@ -7,6 +7,8 @@ import { PostContent } from "@/components/blog/post-content";
 import { TableOfContents } from "@/components/blog/table-of-contents";
 import { Badge } from "@/components/ui/badge";
 import { buildMetadata } from "@/lib/metadata";
+import { publicEnv } from "@/lib/env";
+import { siteConfig } from "@/lib/site";
 import { extractTableOfContents } from "@/lib/markdown";
 import { estimateReadingTime, formatDate } from "@/lib/utils";
 import {
@@ -55,8 +57,33 @@ export default async function BlogPostPage({ params }: BlogPostPageProps) {
   const [adjacentPosts] = await Promise.all([getAdjacentPublishedPosts(slug)]);
   const tableOfContents = extractTableOfContents(post.content);
 
+  const blogPostingSchema = {
+    "@context": "https://schema.org",
+    "@type": "BlogPosting",
+    headline: post.title,
+    description: post.excerpt,
+    datePublished: post.createdAt,
+    dateModified: post.updatedAt,
+    url: `${publicEnv.NEXT_PUBLIC_APP_URL}/blog/${post.slug}`,
+    author: {
+      "@type": "Person",
+      name: siteConfig.name,
+      url: publicEnv.NEXT_PUBLIC_APP_URL,
+    },
+    ...(post.coverImage
+      ? { image: { "@type": "ImageObject", url: post.coverImage } }
+      : {}),
+  };
+
   return (
-    <div className="site-container grid w-full gap-8 py-8 pb-16 sm:py-10 lg:grid-cols-[minmax(0,1fr)_19rem] lg:gap-10 lg:pb-20">
+    <>
+      <script
+        dangerouslySetInnerHTML={{
+          __html: JSON.stringify(blogPostingSchema).replace(/</g, "\\u003c"),
+        }}
+        type="application/ld+json"
+      />
+      <div className="site-container grid w-full gap-8 py-8 pb-16 sm:py-10 lg:grid-cols-[minmax(0,1fr)_19rem] lg:gap-10 lg:pb-20">
       <article className="space-y-8">
         <Link className="section-link" href="/blog">
           <ArrowLeft className="h-4 w-4" />
@@ -136,5 +163,6 @@ export default async function BlogPostPage({ params }: BlogPostPageProps) {
         <TableOfContents items={tableOfContents} />
       </div>
     </div>
+    </>
   );
 }
diff --git a/src/app/global-error.tsx b/src/app/global-error.tsx
new file mode 100644
index 0000000..7cb9837
--- /dev/null
+++ b/src/app/global-error.tsx
@@ -0,0 +1,60 @@
+"use client";
+
+import { useEffect } from "react";
+
+export default function GlobalError({
+  error,
+  reset,
+}: {
+  error: Error & { digest?: string };
+  reset: () => void;
+}) {
+  useEffect(() => {
+    console.error(error);
+  }, [error]);
+
+  return (
+    <html lang="en">
+      <body>
+        <div
+          style={{
+            display: "flex",
+            flexDirection: "column",
+            alignItems: "center",
+            justifyContent: "center",
+            minHeight: "100vh",
+            gap: "1.5rem",
+            padding: "5rem 1rem",
+            textAlign: "center",
+            fontFamily: "system-ui, sans-serif",
+          }}
+        >
+          <p style={{ fontSize: "0.875rem", textTransform: "uppercase", letterSpacing: "0.2em" }}>
+            Critical error
+          </p>
+          <h1 style={{ fontSize: "clamp(2rem, 5vw, 3.5rem)", margin: 0 }}>
+            Something went wrong at the application level.
+          </h1>
+          <p style={{ maxWidth: "36rem", color: "#6b7280" }}>
+            The error was handled safely. You can try refreshing the page or
+            clicking the button below to recover.
+          </p>
+          <button
+            onClick={reset}
+            style={{
+              padding: "0.75rem 1.5rem",
+              fontSize: "1rem",
+              cursor: "pointer",
+              borderRadius: "0.5rem",
+              border: "1px solid #d1d5db",
+              background: "#111827",
+              color: "#fff",
+            }}
+          >
+            Try again
+          </button>
+        </div>
+      </body>
+    </html>
+  );
+}
diff --git a/src/app/layout.tsx b/src/app/layout.tsx
index f8b66d9..35bfbdb 100644
--- a/src/app/layout.tsx
+++ b/src/app/layout.tsx
@@ -5,6 +5,7 @@ import { Footer } from "@/components/layout/footer";
 import { Providers } from "@/components/providers";
 import { buildMetadata } from "@/lib/metadata";
 import { siteConfig } from "@/lib/site";
+import { publicEnv } from "@/lib/env";
 import "./globals.css";
 
 const sora = Sora({
@@ -32,11 +33,27 @@ export default function RootLayout({
 }: Readonly<{
   children: React.ReactNode;
 }>) {
+  const personSchema = {
+    "@context": "https://schema.org",
+    "@type": "Person",
+    name: siteConfig.name,
+    url: publicEnv.NEXT_PUBLIC_APP_URL,
+    sameAs: [siteConfig.github, siteConfig.linkedin],
+    jobTitle: siteConfig.title,
+    email: siteConfig.email,
+  };
+
   return (
     <html lang="en" suppressHydrationWarning>
       <body
         className={`${sora.variable} ${sourceSans.variable} ${jetbrainsMono.variable}`}
       >
+        <script
+          dangerouslySetInnerHTML={{
+            __html: JSON.stringify(personSchema).replace(/</g, "\\u003c"),
+          }}
+          type="application/ld+json"
+        />
         <Providers>
           <div className="page-shell flex min-h-screen flex-col">
             <a className="skip-link" href="#main-content">
diff --git a/src/lib/markdown.ts b/src/lib/markdown.ts
index 7aa0069..5146987 100644
--- a/src/lib/markdown.ts
+++ b/src/lib/markdown.ts
@@ -74,10 +74,10 @@ export function extractTableOfContents(
       continue;
     }
 
-    const headingText = stripMarkdownSyntax(match[2]);
+    const headingText = stripMarkdownSyntax(match[2] ?? "");
 
     items.push({
-      level: match[1].length,
+      level: (match[1] ?? "").length,
       text: headingText,
       slug: slugForHeading(headingText),
     });
diff --git a/tsconfig.json b/tsconfig.json
index 6a97138..207ef26 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -9,6 +9,7 @@
     "allowJs": false,
     "skipLibCheck": true,
     "strict": true,
+    "noUncheckedIndexedAccess": true,
     "noEmit": true,
     "esModuleInterop": true,
     "module": "esnext",