After we turned on streaming for our assistant, tool calls failed with JSON parse errors and sometimes ran with another call's arguments. We were parsing argument fragments per chunk and keying them by arrival order. Accumulating by index fixed it.
Our chat assistant streamed tokens smoothly on localhost but in production the whole answer appeared after 14 seconds. nginx was buffering the event stream and gzip was holding bytes. How we proved it with curl and fixed it without breaking other routes.
Our enrichment consumers rebalanced every few minutes, lag climbed past two million messages and some records were processed twice. A slow external API pushed batch processing past max.poll.interval.ms. How we proved it, fixed the poll loop and made rebalances cheap.