- Added smooth streaming reveal of streamed tool-call args and `{ input }` partial previews.
- Integrated ToolArgsRevealController in EventController to route partial and final args.
- Implemented UTF-16-safe slicing to prevent surrogate-pair splits during reveal boundaries.
- Implemented reveal lifecycle controls to flush or stop streamed arg frames at message boundaries.
- Added tests for monotonic reveal progression, non-smooth immediate output, and flush/stop behavior.