Inconsistent revalidation behaviour between action and clientAction when returning 400

[meln1k]

I'm using React Router as a...

framework

Reproduction

1. Add the following route:

import { Form, data } from "react-router";

export async function loader() {
    return { foo: "bar" };
}

export async function action() {
    return data(error, { status: 400 });
}

export async function clientAction() {
    const error = { error: "foo" };
    console.log("returning error", error);
    return data(error, { status: 400 });
}

export default function ClickMeForm() {
    return (
        <Form method="post">
            <button>
                Click me
            </button>
        </Form>
    )
}

2. Submit the form, revalidation happens

3. Comment out the clientAction

4. Submit the form, revalidation does not happen

System Info

System:
    OS: macOS 15.2
    CPU: (8) arm64 Apple M1 Pro
    Memory: 13.23 GB / 32.00 GB
    Shell: 5.9 - /bin/zsh
  Binaries:
    Node: 23.4.0 - /opt/homebrew/bin/node
    npm: 10.9.2 - /opt/homebrew/bin/npm
    pnpm: 9.12.1 - /opt/homebrew/bin/pnpm
  Browsers:
    Brave Browser: 131.1.73.104
    Chrome: 131.0.6778.205
    Safari: 18.2
  npmPackages:
    @react-router/dev: ^7.0.1 => 7.1.1 
    @react-router/express: ^7.0.1 => 7.1.1 
    @react-router/node: ^7.0.1 => 7.1.1 
    react-router: ^7.0.1 => 7.1.1 
    vite: ^5.4.11 => 5.4.11

Used Package Manager

npm

Expected Behavior

Client action and server action should handle the errors the same way and do not revalidate if a 400 response returned.

Actual Behavior

Server action and client action behaviours are different when 400 is returned. Error in server action does not cause revalidation, but the client action does revalidate in case of an error.