diff --git a/CHANGELOG.md b/CHANGELOG.md
index 38643bb8..d50309dc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+## 15.0.4 - 2025-10-22
+
+## Changed
+- Swapped out `msw` for `agar-sw`. #TINY-13085
+
 ## 15.0.3 - 2025-10-15
 
 ## Fixed
diff --git a/modules/server/src/main/ts/bedrock/server/RunnerRoutes.ts b/modules/server/src/main/ts/bedrock/server/RunnerRoutes.ts
index 02628c03..4a031bdf 100644
--- a/modules/server/src/main/ts/bedrock/server/RunnerRoutes.ts
+++ b/modules/server/src/main/ts/bedrock/server/RunnerRoutes.ts
@@ -101,7 +101,7 @@ export const generate = async (mode: string, projectdir: string, basedir: string
       Routes.routing('GET', '/lib/jquery', path.dirname(require.resolve('jquery'))),
       Routes.routing('GET', '/lib/core-js-bundle', path.dirname(require.resolve('core-js-bundle'))),
       Routes.routing('GET', '/css', path.join(basedir, 'src/resources/css')),
-      Routes.nodeResolveFile('GET', '/mockServiceWorker.js', projectdir, 'msw', 'lib/mockServiceWorker.js'),
+      Routes.nodeResolveFile('GET', '/agar-sw.js', projectdir, '@ephox/agar-sw', 'dist/agar-sw.js'),
 
       // test code
       Routes.asyncJs('GET', '/compiled/tests.js', (done) => {