TUI display corruption regression on v1.2.27 (previously fixed in v1.2.25) #17793

Description

TUI display corruption that was fixed in v1.2.25 (via #16351) has regressed in v1.2.27. The bottom portion of the screen becomes garbled/corrupted during normal use. Toggling fullscreen (and back) clears the corruption temporarily, but it reappears.

The underlying model output and functionality are correct — this is purely a rendering/display issue.

Steps to Reproduce

1. Launch OpenCode v1.2.27 inside a tmux session in iTerm2
2. Use the TUI normally (send prompts, receive responses)
3. After some interaction, the bottom of the screen becomes garbled with corrupted characters

Workaround

Toggle fullscreen on and off to force a full repaint. This clears the corruption temporarily.

Environment

Launch Method

OpenCode is launched via a wrapper script that runs:

opencode --hostname 0.0.0.0 --port 0

Inside a tmux session (session name varies, typical pane setup).

Additional Context

• Using oh-my-opencode plugin with custom agent configurations
• Multiple MCP servers connected (8+ servers including Context7, GitHub Enterprise, Webex RAG, etc.)
• The issue occurs during regular interactive use, not tied to any specific MCP server or agent

Related Issues

• TUI broken in tmux after 1.2.17 (found root cause) #16351 — TUI broken in tmux after 1.2.17 (closed, fixed in v1.2.25) — This is the original fix that appears to have regressed
• TUI garbled/corrupted display after long output or extended conversation, while underlying model output remains correct #15388 — TUI garbled/corrupted display after long output (open)
• The UI layout appears to be broken when interacting with the agent. #16859 — UI layout broken when interacting with agent (closed)
• TUI is scrambled in last update. Unable to scroll. #16189 — TUI scrambled, unable to scroll (open)
• TUI does not fully repaint after Ctrl+Z + fg when terminal is resized #16327 — TUI does not fully repaint after Ctrl+Z + fg (open)
• OpenCode encounters automatically growing unreadable characters #16507 — Automatically growing unreadable characters (closed)

Expected Behavior

Clean, readable TUI display without corruption at the bottom of the screen.

Actual Behavior

Bottom portion of TUI becomes garbled with corrupted/unreadable characters. Requires fullscreen toggle to temporarily fix.

Screenshot will be added in a follow-up comment once captured.