Progressively enhanced Server Function submission stays pending when bound in a Client Component

[nikhilsnayak]

Link to the code that reproduces this issue

https://github.com/nikhilsnayak/next-client-bind-repro

To Reproduce

1. Clone the linked reproduction.
2. Run bun install followed by bun dev.
3. Disable JavaScript in the browser.
4. Navigate to http://localhost:3000.
5. Click Update client-bound user.
6. The Server Function completes on the server, but the browser navigation remains pending and the returned state is not displayed.

Current vs. Expected behavior

Currently, the form submission remains pending indefinitely, even though the Server Function completes on the server. The state returned by the Server Function is not rendered.

I expect the form submission to complete successfully and the state returned through useActionState to be rendered, just as it is when .bind(...) is called in a Server Component.

Provide environment information

Operating System:
  Platform: linux
  Arch: x64
  Version: #30-Ubuntu SMP PREEMPT_DYNAMIC Fri Jul 31 18:22:54 UTC 2026
  Available memory (MB): 15236
  Available CPU cores: 8
Binaries:
  Node: 24.11.0
  npm: 11.6.1
  Yarn: 1.22.22
  pnpm: 11.24.0
Relevant Packages:
  next: 16.4.0-canary.10 // Latest available version is detected (16.4.0-canary.10).
  eslint-config-next: N/A
  react: 19.2.8
  react-dom: 19.2.8
  typescript: 5.9.3
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

Server Actions, React

Which stage(s) are affected? (Select all that apply)

next dev (local), next start (local)

Additional context

Binding additional arguments with .bind(...) inside a Client Component is a documented pattern in the official Next.js forms guide:

https://nextjs.org/docs/app/guides/forms#passing-additional-arguments

The reproduction includes a working control where .bind(...) is called in a Server Component. The progressively enhanced submission completes correctly in that case.

[Cypher-Aura-19]

I reproduced this on current canary (7421a868ad, Next.js 16.4.0-canary.11) and traced the request end-to-end.

The Server Action itself is decoded and executes successfully. The hang happens during the post-action SSR render inside React.

When .bind() is called inside a Client Component render, React creates a new bound Server Reference with a new pending boundPromise on every render attempt. During the no-JS useActionState postback, Fizz calls $$IS_SIGNATURE_EQUAL, sees that promise as pending, suspends, then retries the render. The retry runs .bind() again, creates another pending promise, and the cycle repeats indefinitely.

Binding in a Server Component works because the bound Server Reference comes through the Flight stream and remains stable across retries.

I also confirmed the generated progressive-enhancement form metadata is effectively the same and Next.js correctly reaches decodeAction() / decodeFormState(), so this appears to be a React Fizz/Flight issue rather than a Next.js action-handler bug.

Relevant React paths:

• packages/react-client/src/ReactFlightReplyClient.js — bind() / isSignatureEqual()
• packages/react-server/src/ReactFizzHooks.js — useActionState

I’m going to investigate a proper React-side regression test/fix rather than adding a Next.js-specific workaround here.