[bug] TUI rendering broken: content duplication, text cutoff, and wasted horizontal space #3080

Describe the bug

Since approximately the last few releases (~1 week), the TUI rendering has become increasingly unreliable. Multiple rendering issues occur simultaneously:

1. Content duplication — Messages and UI elements render twice in the conversation view
2. Text cutoff — Long lines get clipped at the edge instead of wrapping properly
3. Wasted horizontal space — The content area renders in a narrow column, leaving a large unused blank area on the right side of the terminal
4. General visual messiness — The overall layout becomes garbled/messy during use

Environment

• Superset Desktop: ~v1.4.3 through v1.4.6 (regression appeared around this range)
• macOS: Darwin 24.6.0
• Agent: Claude Code (Opus 4.6, 1M context)

Steps to Reproduce

1. Open Superset Desktop
2. Start a Claude Code session in a terminal tab
3. Have a conversation with multiple messages / tool calls
4. Observe rendering issues — content gets duplicated, text cuts off, layout breaks

The issue appears consistently and does not require specific actions to trigger — normal usage is sufficient.

Expected Behavior

• Messages should render once, not be duplicated
• Text should wrap correctly within the available terminal width
• The full terminal width should be utilized for content rendering
• The UI should remain clean and readable throughout the conversation

Actual Behavior

• Messages frequently appear twice in the conversation view
• Text is cut off at terminal edges
• A large portion of the horizontal space is unused (content renders in a narrow left column)
• The overall TUI layout is garbled and hard to read

Screenshots

Additional Context

• Reproducibility: Frequent / nearly always
• Regression window: Started approximately 1 week ago across recent releases
• Potentially related: [bug] When I switch away from a terminal tab and come back, the input bar appears twice. Additionally, the terminal view is auto-scrolled to the bottom, leaving a large blank space. #1830 (duplicate input bars after tab switching), [bug] scrolling up when claude code is running causes the viewport to scroll to the very top when claude writes a new message #3057 (viewport scrolling issues)