— flutter_markdown re-parses the entire response string on every streamed token. The fix is an append-only AST with monotonic node IDs used as Flutter widget keys. I packaged it as streamdown — a drop-in replacement that's 188× faster on chunked input and produces zero visible flicker. Live on pub.dev today.
The problem
Every ChatGPT-style Flutter app I built had the same broken-feeling moment: code blocks flashing unstyled → styled → unstyled, tables jittering as new cells arrive, scroll position breaking, and the cursor jumping around like the UI is fighting itself.
The root cause is one line, repeated thousands of times during a single streamed response:
StreamBuilder<String>(
