Index: src/routes/posts.js
===================================================================
--- src/routes/posts.js	(revision d18c60e0878b426798d32187e85100a2262f1430)
+++ src/routes/posts.js	(revision 0688b5fcf8935a7e243f429c90946fd67027fb3c)
@@ -247,4 +247,5 @@
   const cw = (req.body.content_warning || '').trim().slice(0, 200);
   const coverAlt = (req.body.cover_alt || '').trim().slice(0, 1500) || null; // cover alt text (a11y)
+  const language = /^[a-z]{2,3}(-[A-Za-z]{2,4})?$/.test(req.body.language || '') ? req.body.language : (res.locals.lang || null); // BCP-47 content language
 
   // Content arrives as user-authored HTML from the WYSIWYG editor — sanitize
@@ -285,11 +286,11 @@
     INSERT INTO posts (
       id, site_id, slug, author_id, title, content, excerpt,
-      status, cover_image_url, cover_video_url, cover_alt, pinned, tags, type, noindex, fan_only, nsfw, content_warning, poll_json, publish_at,
+      status, cover_image_url, cover_video_url, cover_alt, language, pinned, tags, type, noindex, fan_only, nsfw, content_warning, poll_json, publish_at,
       created_at, updated_at, published_at
-    ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+    ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
   `).run(
     postId, site.id, finalSlug, req.session.user.id,
     title || finalSlug, cleanContent, excerpt || '',
-    finalStatus, cover_image_url || null, (req.body.cover_video_url || null), coverAlt, parsePinnedRank(pinned),
+    finalStatus, cover_image_url || null, (req.body.cover_video_url || null), coverAlt, language, parsePinnedRank(pinned),
     JSON.stringify((tags || '').split(',').map(t => t.trim()).filter(Boolean)),
     finalType, noindex ? 1 : 0, fanOnly, nsfw, cw, pollJson, publishAt,
@@ -313,5 +314,5 @@
       ActivityPubService.deliverCreate(site, {
         id: postId, slug: finalSlug, title: title || finalSlug,
-        content: cleanContent, cover_image_url: cover_image_url || null, cover_video_url: req.body.cover_video_url || null, cover_alt: coverAlt,
+        content: cleanContent, cover_image_url: cover_image_url || null, cover_video_url: req.body.cover_video_url || null, cover_alt: coverAlt, language,
         published_at: publishedAt, created_at: now, fan_only: fanOnly, nsfw, content_warning: cw, poll_json: pollJson,
       }).catch(() => { /* best-effort */ });
@@ -381,4 +382,5 @@
   const cw = (req.body.content_warning || '').trim().slice(0, 200);
   const coverAlt = (req.body.cover_alt || '').trim().slice(0, 1500) || null; // cover alt text (a11y)
+  const language = /^[a-z]{2,3}(-[A-Za-z]{2,4})?$/.test(req.body.language || '') ? req.body.language : (res.locals.lang || null); // BCP-47 content language
   const newSlug = req.body.slug;
   const action = req.body.action || 'save';
@@ -424,5 +426,5 @@
     UPDATE posts SET
       title = ?, content = ?, excerpt = ?, status = ?,
-      cover_image_url = ?, cover_video_url = ?, cover_alt = ?, pinned = ?, tags = ?,
+      cover_image_url = ?, cover_video_url = ?, cover_alt = ?, language = ?, pinned = ?, tags = ?,
       type = ?, noindex = ?, fan_only = ?, nsfw = ?, content_warning = ?, poll_json = ?, publish_at = ?,
       slug = ?, published_at = ?, updated_at = ?
@@ -430,5 +432,5 @@
   `).run(
     title, cleanContent, excerpt, finalStatus,
-    cover_image_url || null, (req.body.cover_video_url || null), coverAlt, parsePinnedRank(pinned),
+    cover_image_url || null, (req.body.cover_video_url || null), coverAlt, language, parsePinnedRank(pinned),
     JSON.stringify((tags || '').split(',').map(t => t.trim()).filter(Boolean)),
     finalType, noindex ? 1 : 0, fanOnly, nsfw, cw, pollJson, publishAt,
@@ -456,5 +458,5 @@
     const apPost = {
       id: post.id, slug: finalSlug, title: title || finalSlug,
-      content: cleanContent, cover_image_url: cover_image_url || null, cover_video_url: req.body.cover_video_url || null, cover_alt: coverAlt,
+      content: cleanContent, cover_image_url: cover_image_url || null, cover_video_url: req.body.cover_video_url || null, cover_alt: coverAlt, language,
       published_at: publishedAt, created_at: post.created_at, fan_only: fanOnly, nsfw, content_warning: cw, poll_json: pollJson,
     };