diff --git a/.github/workflows/release-windows.yml b/.github/workflows/release-windows.yml
index 562a2fdf..dcf0e627 100644
--- a/.github/workflows/release-windows.yml
+++ b/.github/workflows/release-windows.yml
@@ -63,7 +63,10 @@ jobs:
       - name: Setup Node.js
         uses: actions/setup-node@v4
         with:
-          node-version: '20'
+          # Exact pin (not '20'): the build bundles Node v20.18.1 as the runtime
+          # for 9router + MCP servers (see build-app-win.ps1 step 3b), so the
+          # toolchain that packages the app must match the runtime that ships.
+          node-version: '20.18.1'
 
       - name: Setup Python (for building bundled python-env)
         uses: actions/setup-python@v5
diff --git a/.nvmrc b/.nvmrc
new file mode 100644
index 00000000..d4b7699d
--- /dev/null
+++ b/.nvmrc
@@ -0,0 +1 @@
+20.18.1