diff --git a/packages/mcp-server/drawio-files.txt b/packages/mcp-server/drawio-files.txt
index 12264fd6..6fdcd242 100644
--- a/packages/mcp-server/drawio-files.txt
+++ b/packages/mcp-server/drawio-files.txt
@@ -31,8 +31,10 @@ js/app.min.js
 js/bootstrap.js
 js/extensions.min.js
 js/main.js
+js/open.js
 js/shapes-14-6-5.min.js
 js/stencils.min.js
 math4/es5/drawio-mathjax.min.js
 mxgraph/images/maximize.gif
+open.html
 shortcuts.svg
diff --git a/packages/mcp-server/scripts/check-drawio-files.mjs b/packages/mcp-server/scripts/check-drawio-files.mjs
index c3b626a6..75575070 100644
--- a/packages/mcp-server/scripts/check-drawio-files.mjs
+++ b/packages/mcp-server/scripts/check-drawio-files.mjs
@@ -327,6 +327,13 @@ async function drive(browser, ui, full) {
     }
     console.log(`  ${opened} of ${actions.length} actions opened a dialog`)
 
+    // File > Open Library from > Browser (libraries=1): the picker is an
+    // iframe on open.html, which loads js/open.js
+    await frame.evaluate(() => window.__ui.pickLibrary(window.App.MODE_BROWSER))
+    await wait(page, 1000)
+    report("library picker")
+    await closeAll()
+
     // Menus: the visible menubar items, the toolbar buttons that open a menu
     // in the other themes, and every menu rendered with its submenus
     const menubarItems = frame.locator(".geMenubar .geItem:visible")