"Failed to queue message" in sveltekit when launched by vscode launch configuration

[zest-dev]

Hello! I'm getting the following error when starting a workflow from vscode launch configurtaion. Directly running pnpm dev works fine.

I'm running on windows with vscode 1.106.3. My local node version is 24.11.1 and vscode's is 22.20.0

I see "Failed to queue message", and a 400 response from an endpoint that expects a websocket request.

Here's a repro in a newly generated sveltekit app: https://github.com/zest-dev/sveltekit-vercel-workflow-debug

The launch config (the example on sveltekit's website):

{
"configurations": [
{
"command": "npm run dev",
"name": "Run development server",
"request": "launch",
"type": "node-terminal"
}
]
}

The error:

The API handler and workflow start:

https://github.com/zest-dev/sveltekit-vercel-workflow-debug/blob/main/src/routes/api/demo/%2Bserver.ts

The workflow:

https://github.com/zest-dev/sveltekit-vercel-workflow-debug/blob/main/src/routes/api/demo/workflow.ts