diff --git a/backend/src/handlers/posts.rs b/backend/src/handlers/posts.rs
index 2371989..27f7d7b 100644
--- a/backend/src/handlers/posts.rs
+++ b/backend/src/handlers/posts.rs
@@ -115,16 +115,22 @@ pub async fn create_post(
         return Err(AppError::Unauthorized);
     }
 
-    validate_slug(&payload.slug)?;
+    let slug = slug::slugify(&payload.slug);
+    if slug.is_empty() {
+        return Err(AppError::BadRequest(
+            "Slug is empty after normalization (try ASCII letters/numbers)".to_string(),
+        ));
+    }
+    validate_slug(&slug)?;
     if let Some(ref old) = payload.old_slug {
         validate_slug(old)?;
     }
 
     let posts_dir = state.data_dir.join("posts");
-    let file_path = posts_dir.join(format!("{}.md", payload.slug));
+    let file_path = posts_dir.join(format!("{}.md", slug));
 
     if let Some(ref old_slug) = payload.old_slug {
-        if old_slug != &payload.slug {
+        if old_slug != &slug {
             let old_path = posts_dir.join(format!("{}.md", old_slug));
             if old_path.exists() {
                 if file_path.exists() {
@@ -134,11 +140,11 @@ pub async fn create_post(
                 }
                 let _guard = state.post_lock.lock().await;
                 fs::rename(&old_path, &file_path).map_err(|e| {
-                    error!("Rename error from {} to {}: {}", old_slug, payload.slug, e);
+                    error!("Rename error from {} to {}: {}", old_slug, slug, e);
                     AppError::Internal("Rename error".to_string(), Some(e.to_string()))
                 })?;
                 drop(_guard);
-                info!("Renamed post from {} to {}", old_slug, payload.slug);
+                info!("Renamed post from {} to {}", old_slug, slug);
             }
         }
     }
@@ -150,11 +156,11 @@ pub async fn create_post(
         draft: payload.draft,
     };
     let contents = serialize_post(&meta, &payload.content)?;
-    write_post_atomic(&state, &payload.slug, &contents).await?;
+    write_post_atomic(&state, &slug, &contents).await?;
 
-    info!("Post saved: {}", payload.slug);
+    info!("Post saved: {}", slug);
     Ok(Json(PostDetail {
-        slug: payload.slug,
+        slug,
         date: meta.date,
         summary: meta.summary,
         tags: meta.tags,
diff --git a/frontend/src/components/PostCard.astro b/frontend/src/components/PostCard.astro
index a91d3d5..447bc20 100644
--- a/frontend/src/components/PostCard.astro
+++ b/frontend/src/components/PostCard.astro
@@ -16,7 +16,7 @@ const formattedDate = new Date(date).toLocaleDateString('en-US', {
 });
 ---
 
-<a href={`/posts/${slug}`} class="group block">
+<a href={`/posts/${encodeURIComponent(slug)}`} class="group block">
     <article class="glass p-5 md:p-8 transition-colors hover:bg-surface0/80 flex flex-col md:flex-row justify-between md:items-center gap-4 md:gap-6">
         <div class="flex-1 min-w-0">
             <div class="flex flex-wrap items-center gap-x-3 gap-y-1 mb-2 text-xs text-subtext0">
diff --git a/frontend/src/components/react/admin/Dashboard.tsx b/frontend/src/components/react/admin/Dashboard.tsx
index 5ac1f19..5fbcda7 100644
--- a/frontend/src/components/react/admin/Dashboard.tsx
+++ b/frontend/src/components/react/admin/Dashboard.tsx
@@ -78,7 +78,7 @@ export default function Dashboard() {
                 <p className="text-xs text-subtext0" style={{ color: 'var(--subtext0)' }}>/posts/{post.slug}</p>
               </div>
               <div className="flex gap-3">
-                <a href={`/admin/editor?edit=${post.slug}`} className="p-2 text-blue hover:bg-blue/10 rounded transition-colors" title="Edit">
+                <a href={`/admin/editor?edit=${encodeURIComponent(post.slug)}`} className="p-2 text-blue hover:bg-blue/10 rounded transition-colors" title="Edit">
                   <svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round"><path d="M17 3a2.85 2.83 0 1 1 4 4L7.5 20.5 2 22l1.5-5.5Z"/><path d="m15 5 4 4"/></svg>
                 </a>
                 <button onClick={() => handleDelete(post.slug)} className="p-2 text-red hover:bg-red/10 rounded transition-colors" title="Delete">
diff --git a/frontend/src/components/react/admin/Editor.tsx b/frontend/src/components/react/admin/Editor.tsx
index 5dfa750..ee00ed3 100644
--- a/frontend/src/components/react/admin/Editor.tsx
+++ b/frontend/src/components/react/admin/Editor.tsx
@@ -218,7 +218,7 @@ export default function Editor({ editSlug }: Props) {
       .map(t => t.trim())
       .filter(Boolean);
     try {
-      await savePost({
+      const saved = await savePost({
         slug,
         old_slug: originalSlug || null,
         date,
@@ -228,7 +228,8 @@ export default function Editor({ editSlug }: Props) {
         content,
       });
       showAlertMsg('Post saved!', 'success');
-      setOriginalSlug(slug);
+      if (saved?.slug && saved.slug !== slug) setSlug(saved.slug);
+      setOriginalSlug(saved?.slug ?? slug);
     } catch (e) {
       showAlertMsg(e instanceof ApiError ? `Error: ${e.message}` : 'Failed to connect to server.', 'error');
     }
@@ -274,7 +275,7 @@ export default function Editor({ editSlug }: Props) {
         </button>
         {originalSlug && (
           <a
-            href={`/posts/${originalSlug}`}
+            href={`/posts/${encodeURIComponent(originalSlug)}`}
             target="_blank"
             rel="noreferrer"
             className="bg-blue text-crust font-bold py-3 px-8 rounded-lg hover:bg-sky transition-all transform hover:scale-105 whitespace-nowrap inline-flex items-center justify-center gap-2"
diff --git a/frontend/src/pages/feed.xml.ts b/frontend/src/pages/feed.xml.ts
index 42c1bc2..de35796 100644
--- a/frontend/src/pages/feed.xml.ts
+++ b/frontend/src/pages/feed.xml.ts
@@ -51,7 +51,7 @@ export const GET: APIRoute = async ({ site }) => {
   const items = posts
     .filter(p => !p.draft)
     .map(p => {
-      const url = `${origin}/posts/${p.slug}`;
+      const url = `${origin}/posts/${encodeURIComponent(p.slug)}`;
       const description = p.summary || p.excerpt || '';
       const pubDate = new Date(p.date).toUTCString();
       const categories = p.tags.map(t => `      <category>${escapeXml(t)}</category>`).join('\n');
diff --git a/frontend/src/pages/posts/[slug].astro b/frontend/src/pages/posts/[slug].astro
index cee8fb6..a0c5434 100644
--- a/frontend/src/pages/posts/[slug].astro
+++ b/frontend/src/pages/posts/[slug].astro
@@ -24,7 +24,7 @@ let html = '';
 let error = '';
 
 try {
-  const response = await fetch(`${API_URL}/api/posts/${slug}`);
+  const response = await fetch(`${API_URL}/api/posts/${encodeURIComponent(slug ?? '')}`);
   if (response.ok) {
     post = await response.json();
     html = renderMarkdown(post!.content);
@@ -98,7 +98,7 @@ const isAdmin = Astro.cookies.get('admin_session')?.value === '1';
             </div>
             <a
               id="edit-link"
-              href={`/admin/editor?edit=${post.slug}`}
+              href={`/admin/editor?edit=${encodeURIComponent(post.slug)}`}
               class={`bg-surface0 hover:bg-surface1 text-blue px-3 py-1.5 md:px-4 md:py-2 rounded border border-surface1 transition-colors inline-flex items-center gap-2 text-sm md:text-base self-start ${isAdmin ? '' : 'hidden'}`}
             >
               <svg xmlns="http://www.w3.org/2000/svg" width="14" height="14" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" class="md:w-4 md:h-4"><path d="M17 3a2.85 2.83 0 1 1 4 4L7.5 20.5 2 22l1.5-5.5Z"/><path d="m15 5 4 4"/></svg>