Clear loaded modules to remove state between runs

CHANGELOG.md

@@ -13,6 +13,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 
 ### Fixed
 
+- Clear loaded modules to remove state between runs (#1287)
 - Fix intermitently failing dropdown test (#1285)
 
 ## [0.34.2] - 2025-12-09

cypress/e2e/spec-wc-pyodide.cy.js

@@ -181,6 +181,49 @@ describe("Running the code with pyodide", () => {
   });
 
 
+  it("reloads imported local files between code runs", () => {
+    cy.get("@editor")
+      .findByLabelText('editor text input')
+      .invoke("text",
+        `from helper import b\nb()`
+      );
+
+    cy.get("@editor").findByRole('button', { name: 'Add file' }).click()
+
+    cy.get("@editor")
+      .findByLabelText(/Name your file/)
+      .type("helper.py");
+
+    cy.get("@editor")
+      .findByRole('dialog')
+      .findByRole('button', { name: 'Add file' }).click()
+
+    cy.get("@editor")
+      .findByLabelText('editor text input')
+      .invoke("text", `def b():\n  print('one')`);
+
+    cy.get("@editor")
+      .findByRole('button', { name: 'Run' }).click();
+
+    cy.get("@editor")
+      .find(".pyodiderunner")
+      .findByLabelText('Text output')
+      .should("contain", "one");
+
+    cy.get("@editor")
+      .findByLabelText('editor text input')
+      .invoke("text", `def b():\n  print('two')`);
+
+    cy.get("@editor")
+      .findByRole('button', { name: 'Run' }).click();
+
+    cy.get("@editor")
+      .find(".pyodiderunner")
+      .findByLabelText('Text output')
+      .should("contain", "two");
+  });
+
+
   it("runs a simple program with a built-in pyodide module", () => {
     runCode(
       "import simplejson as json\nprint(json.dumps(['foo', {'bar': ('baz', None, 1.0, 2)}]))",

src/PyodideWorker.js

@@ -416,7 +416,12 @@ const PyodideWorker = () => {
   const clearPyodideData = async () => {
     postMessage({ method: "handleLoading" });
     await pyodide.runPythonAsync(`
-        # Clear all user-defined variables and modules
+        import sys
+        for name in list(sys.modules):
+            module = sys.modules[name]
+            if hasattr(module, '__file__') and module.__file__ and module.__file__.startswith('/home/pyodide/'):
+                del sys.modules[name]
+
         for name in dir():
             if not name.startswith('_') and not name=='basthon':
                 del globals()[name]