diff --git a/index.html b/index.html
index 2d7f25a..8120c4e 100644
--- a/index.html
+++ b/index.html
@@ -380,6 +380,8 @@
       window.log = console.log
 
       if(new URLSearchParams(window.location.search).get('leporello') == null) {
+        await import('./src/launch.js');
+        /*
         const {init} = await import('./src/index.js');
         (
           document.readyState == 'complete'
@@ -390,6 +392,7 @@
         ).then(() => {
           init(document.getElementById('app'))
         })
+        */
       }
     </script>
   </head>
diff --git a/src/cmd.js b/src/cmd.js
index 3be1d05..3bef6b7 100644
--- a/src/cmd.js
+++ b/src/cmd.js
@@ -759,6 +759,7 @@ const load_dir = (state, dir) => {
     collect_files(dir).map(f => [f.path, f.contents])
   )
 
+  // Clear parse cache and rerun code
   return rerun_code({
     ...state,
     // remove cache
@@ -773,6 +774,15 @@ const create_file = (state, dir, current_module) => {
   return {...load_dir(state, dir), current_module}
 }
 
+const open_run_window = state => {
+  // After we reopen run window, we should reload external modules in the
+  // context of new window. Clear external_imports_cache
+  return rerun_code({
+    ...state,
+    external_imports_cache: null,
+  })
+}
+
 export const get_initial_state = state => {
   const with_files = state.project_dir == null
     ? state
@@ -798,7 +808,7 @@ export const get_initial_state = state => {
 
 export const COMMANDS = {
   input, 
-  rerun_code,
+  open_run_window,
   load_dir,
   create_file,
   step_into,
diff --git a/src/effects.js b/src/effects.js
index d8fc228..e414a04 100644
--- a/src/effects.js
+++ b/src/effects.js
@@ -8,13 +8,21 @@ import {
 import {FLAGS} from './feature_flags.js'
 import {exec} from './index.js'
 
+// Imports in the context of `run_window`, so global variables in loaded
+// modules refer to that window's context 
+const import_in_run_window = url => {
+  return new globalThis.run_window.Function('url', `
+    return import(url)
+  `)(url)
+}
+
 const load_external_imports = async state => {
   if(state.loading_external_imports_state == null) {
     return
   }
   const urls = state.loading_external_imports_state.external_imports
   const results = await Promise.allSettled(
-    urls.map(u => import(
+    urls.map(u => import_in_run_window(
       /^\w+:\/\//.test(u)    
         ? // starts with protocol, import as is
           u
diff --git a/src/index.js b/src/index.js
index 94d953c..021c137 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,5 +1,4 @@
-import {COMMANDS, get_initial_state} from './cmd.js'
-import {active_frame} from './calltree.js'
+import {get_initial_state} from './cmd.js'
 import {UI} from './editor/ui.js'
 import {EFFECTS, render_initial_state, render_common_side_effects} from './effects.js'
 import {load_dir} from './filesystem.js'
@@ -62,10 +61,13 @@ const read_modules = async () => {
   }
 }
 
+let COMMANDS
 let ui
 let state
 
-export const init = (container) => {
+export const init = (container, _COMMANDS) => {
+  COMMANDS = _COMMANDS
+
   set_error_handler(window)
 
   read_modules().then(initial_state => {
diff --git a/src/launch.js b/src/launch.js
new file mode 100644
index 0000000..239f4e1
--- /dev/null
+++ b/src/launch.js
@@ -0,0 +1,6 @@
+// external
+import {init} from './index.js'
+
+import {COMMANDS} from './cmd.js'
+
+init(globalThis.document.getElementById('app'), COMMANDS)