Unable to cancel or abort streaming UI server actions

[AaronFriel]

Feature Description

Provide an ambient AbortController via an API to server actions and a method for cancelling a request.

Use Case

Users may wish to cancel and retry long-running AI requests, especially in streaming and langchain-esque scenarios where completion times are on the order of tens of seconds or longer.

Additional context

Attempting to work around the issue by, e.g., passing a Promise to the server action does not work, as Next.js delays calling the server action while the promise resolves. This can be demonstrated by calling a server action with new Promise<void>((r) => setTimeout(r, 10_000)) and logging the un-awaited value of the promise immediately in the action.

Related issues:

• Bug: promises passed to server actions block on promise parameters facebook/react#28510
• Bug: server actions cannot be cancelled or given abort signals facebook/react#28511

[fjun99]

also interested in this.