- Strip unclosed [TREE_UPDATE] and [METADATA] blocks from display when
response is truncated by max_tokens
- Increase send_message max_tokens from 2000 to 8000 to prevent
truncation of large tree JSON
- Use lightweight validation for progressive tree updates (valid root
node only) instead of strict 5-node minimum — strict validation
still applies at final /generate step
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>