From 878187c68eecf38c324f11ce9a297c220c496260 Mon Sep 17 00:00:00 2001
From: Tanner Linsley <tannerlinsley@gmail.com>
Date: Mon, 10 Aug 2026 10:57:16 -0600
Subject: [PATCH 1/2] Fix RSS enclosure media types

---
 src/routes/rss[.]xml.ts | 14 +++++++++++++-
 tests/rss.test.ts       | 16 ++++++++++++++++
 2 files changed, 29 insertions(+), 1 deletion(-)
 create mode 100644 tests/rss.test.ts

diff --git a/src/routes/rss[.]xml.ts b/src/routes/rss[.]xml.ts
index 732b7474c..51fea5838 100644
--- a/src/routes/rss[.]xml.ts
+++ b/src/routes/rss[.]xml.ts
@@ -12,6 +12,18 @@ function escapeXml(unsafe: string): string {
     .replace(/'/g, '&apos;')
 }
 
+export function getRssImageMediaType(src: string) {
+  const extension = src.match(/\.([^.?#]+)(?:[?#]|$)/)?.[1]?.toLowerCase()
+
+  if (extension === 'jpg' || extension === 'jpeg') return 'image/jpeg'
+  if (extension === 'webp') return 'image/webp'
+  if (extension === 'svg') return 'image/svg+xml'
+  if (extension === 'gif') return 'image/gif'
+  if (extension === 'png') return 'image/png'
+
+  return 'application/octet-stream'
+}
+
 function generateRSSFeed() {
   const posts = getPublishedPosts().slice(0, 50) // Most recent 50 posts
   const siteUrl = 'https://tanstack.com'
@@ -42,7 +54,7 @@ function generateRSSFeed() {
       <pubDate>${pubDate}</pubDate>
       <author>${escapeXml(author)}</author>
       <description>${escapeXml(description)}</description>
-      ${post.headerImage ? `<enclosure url="${escapeXml(siteUrl + post.headerImage)}" type="image/png" />` : ''}
+      ${post.headerImage ? `<enclosure url="${escapeXml(siteUrl + post.headerImage)}" type="${getRssImageMediaType(post.headerImage)}" />` : ''}
     </item>`
     })
     .join('')
diff --git a/tests/rss.test.ts b/tests/rss.test.ts
new file mode 100644
index 000000000..77264ce6a
--- /dev/null
+++ b/tests/rss.test.ts
@@ -0,0 +1,16 @@
+import assert from 'node:assert/strict'
+import test from 'node:test'
+import { getRssImageMediaType } from '../src/routes/rss[.]xml'
+
+test('uses the image media type matching an RSS enclosure URL', () => {
+  assert.equal(getRssImageMediaType('/header.png'), 'image/png')
+  assert.equal(getRssImageMediaType('/header.jpg'), 'image/jpeg')
+  assert.equal(getRssImageMediaType('/header.jpeg'), 'image/jpeg')
+  assert.equal(getRssImageMediaType('/header.webp'), 'image/webp')
+  assert.equal(getRssImageMediaType('/header.svg?v=1'), 'image/svg+xml')
+  assert.equal(getRssImageMediaType('/header.gif#image'), 'image/gif')
+  assert.equal(
+    getRssImageMediaType('/header.unknown'),
+    'application/octet-stream',
+  )
+})

From 7a55af7df5c91c7174d4e36a324465220952e8ad Mon Sep 17 00:00:00 2001
From: Tanner Linsley <tannerlinsley@gmail.com>
Date: Mon, 10 Aug 2026 11:46:48 -0600
Subject: [PATCH 2/2] Limit RSS media detection to paths

---
 src/routes/rss[.]xml.ts | 3 ++-
 tests/rss.test.ts       | 8 ++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/routes/rss[.]xml.ts b/src/routes/rss[.]xml.ts
index 51fea5838..172f38f16 100644
--- a/src/routes/rss[.]xml.ts
+++ b/src/routes/rss[.]xml.ts
@@ -13,7 +13,8 @@ function escapeXml(unsafe: string): string {
 }
 
 export function getRssImageMediaType(src: string) {
-  const extension = src.match(/\.([^.?#]+)(?:[?#]|$)/)?.[1]?.toLowerCase()
+  const path = src.split(/[?#]/, 1)[0]
+  const extension = path.match(/\.([^./]+)$/)?.[1]?.toLowerCase()
 
   if (extension === 'jpg' || extension === 'jpeg') return 'image/jpeg'
   if (extension === 'webp') return 'image/webp'
diff --git a/tests/rss.test.ts b/tests/rss.test.ts
index 77264ce6a..090b808a1 100644
--- a/tests/rss.test.ts
+++ b/tests/rss.test.ts
@@ -9,6 +9,14 @@ test('uses the image media type matching an RSS enclosure URL', () => {
   assert.equal(getRssImageMediaType('/header.webp'), 'image/webp')
   assert.equal(getRssImageMediaType('/header.svg?v=1'), 'image/svg+xml')
   assert.equal(getRssImageMediaType('/header.gif#image'), 'image/gif')
+  assert.equal(
+    getRssImageMediaType('/header?source=original.png'),
+    'application/octet-stream',
+  )
+  assert.equal(
+    getRssImageMediaType('/header#preview.jpg'),
+    'application/octet-stream',
+  )
   assert.equal(
     getRssImageMediaType('/header.unknown'),
     'application/octet-stream',