The /stream-query endpoint previously emitted only tool-lifecycle events plus
one final complete message, so the answer still appeared all at once. Handle
on_chat_model_stream events to emit incremental `content` deltas, accumulate
them for persistence fallback, and consume them on the frontend to build a live
assistant bubble (reconciled with the authoritative final text). Hide the
redundant loading indicator once tokens start arriving.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Ryan Chen