From ca04d0f6e000403dced4bd6cac95c8634813f567 Mon Sep 17 00:00:00 2001
From: goekce <18174744+goekce@users.noreply.github.com>
Date: Fri, 10 Jul 2026 15:10:34 +0200
Subject: [PATCH] Add avif and webm to the list of supported extensions

---
 packages/myst-cli/src/process/site.ts           | 2 ++
 packages/myst-cli/src/utils/resolveExtension.ts | 4 +++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/packages/myst-cli/src/process/site.ts b/packages/myst-cli/src/process/site.ts
index 3867708db..c6e2ed617 100644
--- a/packages/myst-cli/src/process/site.ts
+++ b/packages/myst-cli/src/process/site.ts
@@ -52,6 +52,8 @@ import { cpus } from 'node:os';
 
 const WEB_IMAGE_EXTENSIONS = [
   ImageExtensions.mp4,
+  ImageExtensions.webm,
+  ImageExtensions.avif,
   ImageExtensions.webp,
   ImageExtensions.svg,
   ImageExtensions.gif,
diff --git a/packages/myst-cli/src/utils/resolveExtension.ts b/packages/myst-cli/src/utils/resolveExtension.ts
index 879519bba..f3c5e5e5c 100644
--- a/packages/myst-cli/src/utils/resolveExtension.ts
+++ b/packages/myst-cli/src/utils/resolveExtension.ts
@@ -13,13 +13,15 @@ export enum ImageExtensions {
   pdf = '.pdf',
   eps = '.eps',
   webp = '.webp',
+  avif = '.avif',
   mp4 = '.mp4', // A moving image!
   mov = '.mov',
   avi = '.avi',
+  webm = '.webm',
 }
 
 export const KNOWN_IMAGE_EXTENSIONS = Object.values(ImageExtensions);
-export const KNOWN_VIDEO_EXTENSIONS = ['.mp4', '.mov', '.avi'];
+export const KNOWN_VIDEO_EXTENSIONS = ['.mp4', '.mov', '.avi', '.webm'];
 
 export const VALID_FILE_EXTENSIONS = ['.md', '.ipynb', '.tex', '.myst.json'];
 export const KNOWN_FAST_BUILDS = new Set(['.ipynb', '.md', '.tex', '.myst.json']);