diff --git a/e2e/playwright/import-ui.spec.ts b/e2e/playwright/import-ui.spec.ts
new file mode 100644
index 00000000000..47f55e4252e
--- /dev/null
+++ b/e2e/playwright/import-ui.spec.ts
@@ -0,0 +1,120 @@
+import { expect, test } from '@e2e/playwright/zoo-test'
+import * as fsp from 'fs/promises'
+import path from 'path'
+
+test.describe('Import UI tests', () => {
+  test('shows toast when trying to sketch on imported face', async ({
+    context,
+    page,
+    homePage,
+    toolbar,
+    scene,
+    editor,
+  }) => {
+    await context.folderSetupFn(async (dir) => {
+      const projectDir = path.join(dir, 'import-test')
+      await fsp.mkdir(projectDir, { recursive: true })
+
+      // Create the imported file
+      await fsp.writeFile(
+        path.join(projectDir, 'toBeImported.kcl'),
+        `sketch001 = startSketchOn(XZ)
+profile001 = startProfileAt([281.54, 305.81], sketch001)
+  |> angledLine([0, 123.43], %, $rectangleSegmentA001)
+  |> angledLine([
+       segAng(rectangleSegmentA001) - 90,
+       85.99
+     ], %)
+  |> angledLine([
+       segAng(rectangleSegmentA001),
+       -segLen(rectangleSegmentA001)
+     ], %)
+  |> line(endAbsolute = [profileStartX(%), profileStartY(%)])
+  |> close()
+extrude(profile001, length = 100)`
+      )
+
+      // Create the main file that imports
+      await fsp.writeFile(
+        path.join(projectDir, 'main.kcl'),
+        `import "toBeImported.kcl" as importedCube
+
+importedCube
+
+sketch001 = startSketchOn(XZ)
+profile001 = startProfileAt([-134.53, -56.17], sketch001)
+  |> angledLine([0, 79.05], %, $rectangleSegmentA001)
+  |> angledLine([
+       segAng(rectangleSegmentA001) - 90,
+       76.28
+     ], %)
+  |> angledLine([
+       segAng(rectangleSegmentA001),
+       -segLen(rectangleSegmentA001)
+     ], %, $seg01)
+  |> line(endAbsolute = [profileStartX(%), profileStartY(%)], tag = $seg02)
+  |> close()
+extrude001 = extrude(profile001, length = 100)
+sketch003 = startSketchOn(extrude001, seg02)
+sketch002 = startSketchOn(extrude001, seg01)`
+      )
+    })
+
+    await homePage.openProject('import-test')
+    await scene.waitForExecutionDone()
+
+    await scene.moveCameraTo(
+      {
+        x: -114,
+        y: -897,
+        z: 475,
+      },
+      {
+        x: -114,
+        y: -51,
+        z: 83,
+      }
+    )
+    const [_, hoverOverNonImport] = scene.makeMouseHelpers(611, 364)
+    const [importedFaceClick, hoverOverImported] = scene.makeMouseHelpers(
+      940,
+      150
+    )
+
+    await test.step('check code highlight works for code define in the file being edited', async () => {
+      await hoverOverNonImport()
+      await editor.expectState({
+        highlightedCode: 'startProfileAt([-134.53,-56.17],sketch001)',
+        diagnostics: [],
+        activeLines: ['import"toBeImported.kcl"asimportedCube'],
+      })
+    })
+
+    await test.step('check code does nothing when geometry is defined in an import', async () => {
+      await hoverOverImported()
+      await editor.expectState({
+        highlightedCode: '',
+        diagnostics: [],
+        activeLines: ['import"toBeImported.kcl"asimportedCube'],
+      })
+    })
+
+    await test.step('check the user is warned when sketching on a imported face', async () => {
+      // Start sketch mode
+      await toolbar.startSketchPlaneSelection()
+
+      // Click on a face from the imported model
+      // await new Promise(() => {})
+      await importedFaceClick()
+
+      // Verify toast appears with correct content
+      await expect(page.getByText('This face is from an import')).toBeVisible()
+      await expect(
+        page.locator('.font-mono').getByText('toBeImported.kcl')
+      ).toBeVisible()
+      await expect(
+        page.getByText('Please select this from the files pane to edit')
+      ).toBeVisible()
+    })
+  })
+})
diff --git a/src/components/SketchOnImportToast.tsx b/src/components/SketchOnImportToast.tsx
new file mode 100644
index 00000000000..fd51dc0e1d7
--- /dev/null
+++ b/src/components/SketchOnImportToast.tsx
@@ -0,0 +1,21 @@
+import toast from 'react-hot-toast'
+
+interface SketchOnImportToastProps {
+  fileName: string
+}
+
+export function SketchOnImportToast({ fileName }: SketchOnImportToastProps) {
+  return (
+    <div className="flex flex-col gap-2">
+      <span>This face is from an import</span>
+      <span className="font-mono text-sm bg-gray-100 dark:bg-gray-800 px-2 py-1 rounded">
+        {fileName}
+      </span>
+      <span>Please select this from the files pane to edit</span>
+    </div>
+  )
+}
+
+export function showSketchOnImportToast(fileName: string) {
+  toast.error(<SketchOnImportToast fileName={fileName} />)
+}
diff --git a/src/editor/manager.ts b/src/editor/manager.ts
index 0991b4e53d1..14e6400a97a 100644
--- a/src/editor/manager.ts
+++ b/src/editor/manager.ts
@@ -13,6 +13,7 @@ import {
 } from '@src/editor/highlightextension'
 import type { KclManager } from '@src/lang/KclSingleton'
 import type { EngineCommandManager } from '@src/lang/std/engineConnection'
+import { isTopLevelModule } from '@src/lang/util'
 import { markOnce } from '@src/lib/performance'
 import type { Selection, Selections } from '@src/lib/selections'
 import { processCodeMirrorRanges } from '@src/lib/selections'
@@ -151,12 +152,12 @@ export default class EditorManager {
     selection: Array<Selection['codeRef']['range']>
   ): Array<[number, number]> {
     if (!this._editorView) {
-      return selection.map((s): [number, number] => {
+      return selection.filter(isTopLevelModule).map((s): [number, number] => {
         return [s[0], s[1]]
       })
     }
 
-    return selection.map((s): [number, number] => {
+    return selection.filter(isTopLevelModule).map((s): [number, number] => {
       const safeEnd = Math.min(s[1], this._editorView?.state.doc.length || s[1])
       return [s[0], safeEnd]
     })
diff --git a/src/hooks/useEngineConnectionSubscriptions.ts b/src/hooks/useEngineConnectionSubscriptions.ts
index ee11b649143..d4aeeb35e5e 100644
--- a/src/hooks/useEngineConnectionSubscriptions.ts
+++ b/src/hooks/useEngineConnectionSubscriptions.ts
@@ -1,5 +1,6 @@
 import { useEffect, useRef } from 'react'
 
+import { showSketchOnImportToast } from '@src/components/SketchOnImportToast'
 import { useModelingContext } from '@src/hooks/useModelingContext'
 import { getNodeFromPath } from '@src/lang/queryAst'
 import { getNodePathFromSourceRange } from '@src/lang/queryAstNodePathUtils'
@@ -24,10 +25,12 @@ import {
   sceneInfra,
 } from '@src/lib/singletons'
 import { err, reportRejection } from '@src/lib/trap'
+import { getModuleId } from '@src/lib/utils'
 import type {
   EdgeCutInfo,
   ExtrudeFacePlane,
 } from '@src/machines/modelingMachine'
+import toast from 'react-hot-toast'
 
 export function useEngineConnectionSubscriptions() {
   const { send, context, state } = useModelingContext()
@@ -186,6 +189,29 @@ export function useEngineConnectionSubscriptions() {
                 faceId,
                 kclManager.artifactGraph
               )
+              if (!err(extrusion)) {
+                const fileIndex = getModuleId(extrusion.codeRef.range)
+                if (fileIndex !== 0) {
+                  const importDetails =
+                    kclManager.execState.filenames[fileIndex]
+                  if (!importDetails) {
+                    toast.error("can't sketch on this face")
+                    return
+                  }
+                  if (importDetails?.type === 'Local') {
+                    const paths = importDetails.value.split('/')
+                    const fileName = paths[paths.length - 1]
+                    showSketchOnImportToast(fileName)
+                  } else if (
+                    importDetails?.type === 'Main' ||
+                    importDetails?.type === 'Std'
+                  ) {
+                    toast.error("can't sketch on this face")
+                  } else {
+                    const _exhaustiveCheck: never = importDetails
+                  }
+                }
+              }
 
               if (
                 artifact?.type !== 'cap' &&
diff --git a/src/lib/utils.ts b/src/lib/utils.ts
index 30ff5576a50..30dec53865b 100644
--- a/src/lib/utils.ts
+++ b/src/lib/utils.ts
@@ -469,3 +469,7 @@ export function binaryToUuid(
     hexValues.slice(10, 16).join(''),
   ].join('-')
 }
+
+export function getModuleId(sourceRange: SourceRange) {
+  return sourceRange[2]
+}