Chunk-level stream timeout for ChatClient

[DiegoGBrisa]

Problem

When an LLM provider hangs mid-stream (connection stays open but no chunks arrive), there's no built-in way to detect it and abort. The stream just sits there indefinitely. This happens more often than you'd expect with some providers — especially during high load or when tool execution takes longer than anticipated on the server.

You can pass an AbortSignal to the connection adapter, but that requires managing timers externally and resetting them on every chunk, which is boilerplate that every app ends up reimplementing.

Proposal

A streamTimeout option on ChatClient (and by extension useChat / framework wrappers) that aborts the stream if no chunk arrives within the specified duration:

  const chat = useChat({
    connection: adapter,
    streamTimeout: 30_000, // abort if no chunk arrives within 30s
  })

The timeout resets on every received chunk, so it's a per-chunk idle timeout — not a total duration limit. When it fires, it triggers the same error flow as stop() or a network failure, so onError and status updates work as expected.

This could live in StreamProcessor or at the ChatClient level wrapping the connection's AsyncIterable.