[Bug] UI rendering broken with overlapping text and buffer corruption in v2.1.202

Bug Description
Claude Code 2.1.202 — overlapping/garbled TUI rendering inside tmux

The TUI renders with overlapping text — output lines are drawn over one another, and typed characters overlap at the input prompt (new content painted without erasing the old). Occurs only inside tmux; a bare iTerm2 session (no tmux) renders cleanly. Appeared after updating Claude Code — suspected renderer regression (new text drawn over stale cells rather than clear-then-draw; a cursor-position / clear-to-EOL / wrap disagreement, distinct from a "blank pane" stuck-frame).

Environment Info

• Platform: darwin
• Terminal: tmux
• Version: 2.1.197
• Claude Code: 2.1.202
• tmux: 3.7b
• Terminal: iTerm2 3.6.11, macOS (Apple Silicon, Darwin 24.6.0)
• TERM outside tmux: xterm-256color; inside tmux: tmux-256color
• tmux truecolor enabled (terminal-overrides ",xterm*:Tc")
• Feedback ID: 41a4d52d-c8bf-4b1b-9227-bd5b30feb05e

Repro
tmux -L cctest -f /dev/null new-session # clean tmux, no user config
claude # inside the tmux pane
Let output scroll and type in the input box; characters/lines overlap.

Not synchronized-output terminfo: tmux answers DECRQM mode 2026 "supported" regardless of terminal-overrides (Sync@ stripping has no effect), so a terminal-side sync toggle isn't available — a Claude-Code-side rendering/sync toggle or downgrade is the only lever.

Errors

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