- Agent service (crossbeam channels): TUI never blocks on gRPC I/O.
Chat runs on a background tokio task, events flow back via bounded
crossbeam channel. Designed as a library-friendly internal RPC.
- Virtual viewport: pre-wrap text with textwrap on content/width change,
slice only visible rows for rendering. Paragraph gets no Wrap, no
scroll() — pure O(viewport) per frame.
- Event drain loop: coalesce all queued terminal events before drawing.
Filters MouseEventKind::Moved (crossterm's EnableMouseCapture floods
these via ?1003h any-event tracking). Single redraw per batch.
- Conditional drawing: skip frames when nothing changed (needs_redraw).
- Mouse wheel + PageUp/Down + Home/End scrolling, command history
(Up/Down, persistent to .sunbeam/history), Alt+L debug log overlay.
- Proto: SessionReady now includes history entries + resumed flag.
Session resume loads conversation from Matrix room on reconnect.
- Default model: devstral-small-latest (was devstral-small-2506).