ReferenceError: $$default is not defined - Workflow execution fails in Local World on Turbo monorepo

[waldhari1]

Workflows fail during execution in Local World with ReferenceError: $$default is not defined when running in a Turbo monorepo environment. The workflow triggers successfully and queues successfully, but fails immediately (within 10ms) during VM context execution.

This error persists across all tested configurations including the exact setup reported as "working" in Issue #35 (workflow@4.0.1-beta.2 + next@16.0.0).

Environment
Operating System: WSL2 Ubuntu (Linux 6.6.87.2-microsoft-standard-WSL2) Node.js: v22.11.0 Package Manager: pnpm 9.15.9 Monorepo Tool: Turborepo 2.3.3 Monorepo Structure:

Shared packages: @waltoria/shared-db (Prisma), @waltoria/uuid-utils
Multiple Next.js apps in apps/ directory
Workflows in: apps/advisor-activity-nexus/workflows/
Deployment Target: Vercel (but testing locally first)

Tested Configurations (ALL FAILED)

Next.js Workflow DevKit Bundler Result

1 16.0.1 4.0.1-beta.11 Turbopack ❌ Workflow must be a function, but got "undefined"
2 16.0.1 4.0.1-beta.11 webpack ❌ $$default is not defined
3 16.0.1 4.0.1-beta.15 Turbopack ❌ Server crash: withWorkflow export not found
4 15.1.3 4.0.1-beta.11 webpack ❌ $$default is not defined
5 16.0.0 4.0.1-beta.2 Turbopack ❌ $$default is not defined
Note on Configuration #5: This is the exact configuration reported as working in Issue #35, but it fails in our monorepo environment.

Full bug report attached here as a .md file

GITHUB-ISSUE-DRAFT.md

[pushkar-mst]

Are you exporting the step/workflow function with "export default" or just "export"

[TooTallNate]

Thank you for the detailed markdown file. I was able to reproduce the issue. Taking a look.

[waldhari1]

wow incredible, thank you for your great work, I'm glad i was able to contribute meaningfully to this project.... i guess on my end to get the fix, I would have to wait until your PR is revied and merged, then I install the new beta software, right?

[TooTallNate]

You can try it out right now actually, we create tarballs of every pull request that you can install with your package manager. Run the following:

npm install https://workflow-docs-git-fix-gh-367.vercel.sh/workflow.tgz

[waldhari1]

lol, this is actually incredible, great....i' would share some feedback. Testing now

[waldhari1]

Update: Testing PR #373 Tarball - New Local World Bug Found

Installation Success ✅

Successfully installed the PR #373 fix via tarball:

pnpm add https://workflow-docs-git-fix-gh-367.vercel.sh/workflow.tgz

Installed version: workflow@4.0.1-beta.17-3243a7b

New Issue: "Cannot find module 'local'" ❌

After installing the PR tarball, we now encounter a different error when trying to execute workflows:

⨯ Error: Cannot find module 'local'
Require stack:
- /home/waldhari/software-packages/waltoria/apps/advisor-activity-nexus/index.js
    at module evaluation (app/api/workflows/trigger/[workflowName]/route.ts:16:1)
> 16 | import { start } from 'workflow/api'

Root Cause Analysis

Traced the issue to @workflow/core/dist/runtime/world.js:

// Line 20: Determines which world to use
const targetWorld = process.env.WORKFLOW_TARGET_WORLD || defaultWorld();

// Line 37: If not 'embedded' or 'vercel', tries to require() as module
const mod = require(targetWorld);

Problem: Something in the Turbopack bundling process appears to be causing targetWorld to resolve to the string 'local' instead of 'embedded', which then executes require('local') — a module that doesn't exist.

Environment Details

• Next.js: 16.0.0 (Turbopack)
• Project Structure: Turbo monorepo
• Runtime: Local World (development)
• Module Resolution: ESM with createRequire for CommonJS interop
• Server: Starts successfully, workflows discovered, but execution fails

Observations

1. Server startup is clean — no crashes during initialization
2. Workflow directives are discovered successfully
3. Error only occurs when actually invoking a workflow via API route
4. The @workflow/world-local package IS installed correctly as a dependency
5. All world packages are properly linked in pnpm store

Configuration

// next.config.mjs
import { createRequire } from 'module';
const require = createRequire(import.meta.url);
const { withWorkflow } = require('workflow/next');

export default withWorkflow(nextConfig);

No WORKFLOW_TARGET_WORLD environment variable is set (should default to 'embedded').

Status of Original Bug

Cannot confirm if the $default is not defined error is fixed because we're blocked by this new Local World module resolution issue.

Next Steps

We're considering deploying to Vercel staging to test if the original fix works in Vercel World (which would bypass this Local World bug entirely).

Would appreciate any guidance on:

1. Whether this is a known Turbopack-specific issue
2. If there's a workaround for Local World module resolution
3. Whether Vercel World testing would be sufficient to validate the $default fix

Thanks for the quick turnaround on the PR! 🙏

@TooTallNate