TUI unresponsive to keyboard input inside tmux: setRawMode fails with EBADF (errno 9)

[AungMyoKyaw]

Bug Description

When running opencode inside a tmux session, the TUI renders correctly but is completely unresponsive to all keyboard input. No keys register — typing, arrow keys, Enter, Escape, Ctrl+C, keyboard shortcuts all silently ignored. The UI appears frozen. Works perfectly outside tmux.

Environment

• OS: macOS (Apple Silicon, arm64)
• Terminal: Ghostty
• tmux: next-3.7
• opencode version: 0.0.0-dev-202604251526 (April 25, 2026 dev build)
• Installation: via Bun (bunx opencode-ai@latest)
• Shell: zsh

Root Cause Found

The debug log (--print-logs --log-level DEBUG) reveals the failure:

ERROR service=server-proxy e=setRawMode failed with errno: 9 exception
ERROR service=server-proxy error=setRawMode failed with errno: 9 process error

errno 9 = EBADF (Bad file descriptor). The setRawMode() call tries to operate on a file descriptor that is not a valid terminal.

Why This Happens (TTY Discrepancy)

Inside tmux, the process environment differs from outside:

• stdin (fd 0): IS a TTY — [ -t 0 ] returns true
• stdout (fd 1): NOT a TTY — [ -t 1 ] returns false
• tty command returns /dev/ttys006 (valid PTY)

Outside tmux, both stdin and stdout are TTYs.

Conclusion: setRawMode() is called on the stdout file descriptor (fd 1), which is not a TTY inside tmux, causing the EBADF failure. The correct file descriptor for raw mode is stdin (fd 0), since raw mode controls input buffering.

Reproduction Steps

1. Start a tmux session: tmux
2. Run opencode: opencode
3. OpenCode TUI renders (UI elements visible)
4. Try to type anything — no input is registered
5. Run with debug logging: OPENCODE_LOG_LEVEL=DEBUG opencode --print-logs --log-level DEBUG 2>/tmp/op-debug.log
6. Check the log for: setRawMode failed with errno: 9

What Was Tested (Bisect)

• Tmux config is NOT the cause: Tested 7 progressive tmux configs (minimal → full), all produce same error
• Confirmed: A minimal Bubble Tea v1.3.10 program (tea.WithAltScreen()) works correctly inside all tmux configs — keyboard input is received normally
• Confirmed: stty shows terminal is in canonical mode (icanon) inside tmux, confirming raw mode was never set
• Confirmed: Running outside tmux shows no setRawMode error

Workaround

None found. Setting extended-keys always, removing allow-passthrough, or using a minimal tmux configuration does not resolve the issue.

Possible Fix Direction

• setRawMode() should use the stdin file descriptor (fd 0) instead of stdout (fd 1), since raw mode is about disabling input line buffering
• Or opencode's TUI initialization should detect when stdout is not a TTY and fall back to stdin for raw mode control
• Compare with Bubble Tea v1.3.10's NewProgram which works correctly inside tmux

Related Issues

• TUI broken in tmux after 1.2.17 (found root cause) #16351 — "TUI broken in tmux after 1.2.17" (identical symptoms, regression reverted)
• [Bug]: Process crashes with "setRawMode failed with errno: 5 (EIO)" when terminal disconnects #15286 — "setRawMode failed with errno: 5 (EIO)" when terminal disconnects
• Missing SIGHUP handler causes orphaned processes to leak ~4.7 GB each after terminal death #14504 — Missing SIGHUP handler causes orphaned processes
• Terminal escape sequences printed on startup in tmux #16547 — Terminal escape sequences printed on startup in tmux
• TUI leaves terminal in mouse-reporting/raw mode; keystrokes / mouse events print as ^[[<... after exit or crash #10610 — TUI leaves terminal in raw mode after exit

Logs

Complete error log:

INFO  2026-04-25T18:07:49 +252ms service=server-proxy version=0.0.0-dev-202604251526 args=["--print-logs"] process_role=main run_id=641a2824-b437-4873-9634-5bf28b0e7e70 opencode
ERROR 2026-04-25T18:07:50 +1124ms service=server-proxy e=setRawMode failed with errno: 9 exception
ERROR 2026-04-25T18:07:50 +1ms service=server-proxy error=setRawMode failed with errno: 9 process error

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• TUI broken inside Linux tmux #16967: TUI broken inside Linux tmux — same symptom (cannot input text, TUI unresponsive in tmux), still open
• TUI broken in tmux after 1.2.17 (found root cause) #16351: TUI broken in tmux after 1.2.17 (closed/solved in 1.2.25) — identical symptoms with keyboard input completely ignored inside tmux; your issue references this one

If your problem persists on the current version and differs from the above (e.g. different root cause or environment), please clarify so maintainers can distinguish this from prior reports.