Architecture C from expert panel review: add run_turn_to<W: Write>
that writes all output (spinners, markdown, compaction logs) to a
custom writer instead of hardcoding stdout.
In the TUI path, we pass a Vec<u8> buffer. Zero bytes hit the real
terminal during a turn, so nothing bleeds past the conversation pane
boundary into the dashboard. After the turn, the buffer contents are
stripped of ANSI codes and pushed into the conversation pane where
wrap_line() constrains them to the pane width.
Key changes:
- run_turn() is now a thin wrapper: run_turn_to(input, stdout, true)
- run_turn_to<W: Write>(input, out, emit_output) is the real impl
- All println! → writeln!(out, ...), &mut stdout → out
- emit_output=false in TUI mode prevents runtime tool-stream output
- Add strip_ansi() helper for cleaning captured buffer text
- Remove Clear(ClearType::All) from redraw_after_turn (no debris to wipe)
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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