Summary

Fixes #542 — [DONE] SSE end-of-stream marker being passed to serde_json::from_str in stream(), causing a deserialization error.

Root Cause

In v0.36.0 (PR #537), the streaming pipeline was refactored to remove reqwest-eventsource. The old stream() function checked for [DONE] before deserialization. The new stream() delegates to stream_mapped_raw_events, which checks [DONE] after the mapper closure — and the mapper in stream() is serde_json::from_str.

Fix

Move the [DONE] check before the event_mapper call in both implementations:

• WASM (futures::stream::unfold): Check [DONE] and return None to end the stream cleanly. Removed the finished state variable since it's no longer needed.
• Non-WASM (tokio::mpsc): Check [DONE] and break before calling event_mapper.

Test Plan

• Existing unit tests pass (15 passed, 11 skipped — require API key)
• Change is minimal and restores the pre-refactor behavior

Before

let done = event.data == "[DONE]";
// ...
let response = event_mapper(event); // [DONE] passed to JSON parser → error!
return Some((response, (event_stream, event_mapper, done)));

After

if event.data == "[DONE]" {
    return None; // clean stream termination
}
// ...
let response = event_mapper(event);
return Some((response, (event_stream, event_mapper)));