Bundler Error while importing WorkflowChatTransport

[avi1989]

After upgrading the workflow and @workflow/ai packages to 4.0.1-beta.39, I am unable to import WorkflowChatTransport in any client component. It looks like nextjs is trying to bundle @workflow/core into a client bundle.

This can be reproduced in vercel/workflow-examples by upgrading the package versions and running the pnpm dev on the flight booking app as I did here

The full error is below.

## Error Type
Build Error

## Error Message
Code generation for chunk item errored

## Build Output
./node_modules/.pnpm/@workflow+core@4.0.1-beta.33_@aws-sdk+client-sts@3.914.0_@opentelemetry+api@1.9.0/node_modules/@workflow/core/dist/runtime/world.js
Code generation for chunk item errored
An error occurred while generating the chunk item [project]/node_modules/.pnpm/@workflow+core@4.0.1-beta.33_@aws-sdk+client-sts@3.914.0_@opentelemetry+api@1.9.0/node_modules/@workflow/core/dist/runtime/world.js [app-client] (ecmascript)

Caused by:
- the chunking context (unknown) does not support external modules (request: node:module)

Debug info:
- An error occurred while generating the chunk item [project]/node_modules/.pnpm/@workflow+core@4.0.1-beta.33_@aws-sdk+client-sts@3.914.0_@opentelemetry+api@1.9.0/node_modules/@workflow/core/dist/runtime/world.js [app-client] (ecmascript)
- Execution of <ModuleChunkItem as EcmascriptChunkItem>::content_with_async_module_info failed
- Execution of *EcmascriptChunkItemContent::new failed
- Execution of EcmascriptModuleContent::new failed
- the chunking context (unknown) does not support external modules (request: node:module)

Import traces:
  Client Component Browser:
    ./node_modules/.pnpm/@workflow+core@4.0.1-beta.33_@aws-sdk+client-sts@3.914.0_@opentelemetry+api@1.9.0/node_modules/@workflow/core/dist/runtime/world.js [Client Component Browser]
    ./node_modules/.pnpm/@workflow+core@4.0.1-beta.33_@aws-sdk+client-sts@3.914.0_@opentelemetry+api@1.9.0/node_modules/@workflow/core/dist/serialization.js [Client Component Browser]
    ./node_modules/.pnpm/@workflow+core@4.0.1-beta.33_@aws-sdk+client-sts@3.914.0_@opentelemetry+api@1.9.0/node_modules/@workflow/core/dist/step/writable-stream.js [Client Component Browser]
    ./node_modules/.pnpm/@workflow+core@4.0.1-beta.33_@aws-sdk+client-sts@3.914.0_@opentelemetry+api@1.9.0/node_modules/@workflow/core/dist/index.js [Client Component Browser]
    ./node_modules/.pnpm/@workflow+ai@4.0.1-beta.39_ai@5.0.76_zod@4.1.12__workflow@4.0.1-beta.39_@aws-sdk+client_9829537cd50594c6b8f43bea9dee5ca1/node_modules/@workflow/ai/dist/agent/durable-agent.js [Client Component Browser]
    ./node_modules/.pnpm/@workflow+ai@4.0.1-beta.39_ai@5.0.76_zod@4.1.12__workflow@4.0.1-beta.39_@aws-sdk+client_9829537cd50594c6b8f43bea9dee5ca1/node_modules/@workflow/ai/dist/index.js [Client Component Browser]
    ./app/page.tsx [Client Component Browser]
    ./app/page.tsx [Server Component]

  Client Component SSR:
    ./node_modules/.pnpm/@workflow+core@4.0.1-beta.33_@aws-sdk+client-sts@3.914.0_@opentelemetry+api@1.9.0/node_modules/@workflow/core/dist/runtime/world.js [Client Component SSR]
    ./node_modules/.pnpm/@workflow+core@4.0.1-beta.33_@aws-sdk+client-sts@3.914.0_@opentelemetry+api@1.9.0/node_modules/@workflow/core/dist/serialization.js [Client Component SSR]
    ./node_modules/.pnpm/@workflow+core@4.0.1-beta.33_@aws-sdk+client-sts@3.914.0_@opentelemetry+api@1.9.0/node_modules/@workflow/core/dist/step/writable-stream.js [Client Component SSR]
    ./node_modules/.pnpm/@workflow+core@4.0.1-beta.33_@aws-sdk+client-sts@3.914.0_@opentelemetry+api@1.9.0/node_modules/@workflow/core/dist/index.js [Client Component SSR]
    ./node_modules/.pnpm/@workflow+ai@4.0.1-beta.39_ai@5.0.76_zod@4.1.12__workflow@4.0.1-beta.39_@aws-sdk+client_9829537cd50594c6b8f43bea9dee5ca1/node_modules/@workflow/ai/dist/agent/durable-agent.js [Client Component SSR]
    ./node_modules/.pnpm/@workflow+ai@4.0.1-beta.39_ai@5.0.76_zod@4.1.12__workflow@4.0.1-beta.39_@aws-sdk+client_9829537cd50594c6b8f43bea9dee5ca1/node_modules/@workflow/ai/dist/index.js [Client Component SSR]
    ./app/page.tsx [Client Component SSR]
    ./app/page.tsx [Server Component]

Next.js version: 16.0.10 (Turbopack)

Additional Info
Adding

  experimental: {
    optimizePackageImports: ['@workflow/ai'],
  },
}

to next.config.ts makes the app work.

[gsathya]

Seeing this as well. Bisected to beta.36 as the first failing release. Looking at the changes in that release, #640 looks relevant from a quick look? @ijjk can you help check if this from your PR? (Ah, looking at fix in #710, #640 seems unrelated)