diff --git a/.changeset/vsix-immer-bundle.md b/.changeset/vsix-immer-bundle.md
new file mode 100644
index 000000000..abfe84ed6
--- /dev/null
+++ b/.changeset/vsix-immer-bundle.md
@@ -0,0 +1,4 @@
+---
+"pythinker": patch
+---
+Fix the extension bundle to inline `immer`.
diff --git a/apps/vscode/tsdown.config.ts b/apps/vscode/tsdown.config.ts
index 945e27efe..84bdd8746 100644
--- a/apps/vscode/tsdown.config.ts
+++ b/apps/vscode/tsdown.config.ts
@@ -51,7 +51,7 @@ export default defineConfig({
   },
   deps: {
     onlyBundle: false,
-    alwaysBundle: [/^@pymodel\//, 'zod', 'diff'],
+    alwaysBundle: [/^@pymodel\//, 'zod', 'diff', 'immer'],
     neverBundle: ['vscode'],
   },
   outputOptions: {