Bug: Forms are reset when action fails

[OliverJAsh]

React version: 19.2.1

Steps To Reproduce

1. Enter some text into the input and submit. The action will fail.

Link to code example:

https://codesandbox.io/p/devbox/funny-jang-3zj83m?file=%2Fsrc%2Findex.js%3A7%2C4&workspaceId=ws_4qKVDKGuRrrvd8oLfoRWSz

The current behavior

The form is reset.

The expected behavior

The form is not reset when the action fails. The docs suggest that reset should only happen when the action is successful:

After the action function succeeds, all uncontrolled field elements in the form are reset.

Related: #29034

[OliverJAsh]

It seems this happens even when we use onSubmit + startTransition instead of action: https://codesandbox.io/p/devbox/practical-lucy-kyv24g?file=%2Fsrc%2Findex.js%3A4%2C20&workspaceId=ws_4qKVDKGuRrrvd8oLfoRWSz

I guess it's because React remounts the tree when the error boundary receives an error. In which case I suppose this is working as intended?