codex - 💡(How to fix) Fix Codex CLI TUI drops keyboard input in RunPod/JupyterLab terminal; raw /dev/tty reader fixes input loss [2 comments, 2 participants]

What version of Codex CLI is running?

0.125.0

What subscription do you have?

ChatGPT Plus

Which model were you using?

gpt-5.5

What platform is your computer?

Remote environment: Ubuntu 22.04.5 LTS on RunPod container/pod Client machine: Windows 10, using Chrome browser to access RunPod JupyterLab terminal

What terminal emulator and version are you using (if applicable)?

RunPod JupyterLab terminal in Chrome browser, via RunPod proxy URL. The terminal appears to be the JupyterLab web terminal / xterm.js style terminal.

What issue are you seeing?

Codex CLI TUI v0.125.0 starts normally in a RunPod/JupyterLab web terminal, but keyboard input becomes unreliable. When typing into the Codex prompt, only some characters reach the TUI/event stream.

Example: typing abc123 sometimes resulted in only a partial sequence being received, such as:

RAW KEY CHARS: as COUNT: 2

This made the TUI effectively unusable.

This does not appear to be a general terminal-byte-delivery problem. A direct raw /dev/tty probe in the same terminal receives the full input correctly:

BYTES: [97] CHARS: 'a' BYTES: [98] CHARS: 'b' BYTES: [99] CHARS: 'c' BYTES: [49] CHARS: '1' BYTES: [50] CHARS: '2' BYTES: [51] CHARS: '3' BYTES: [3] CHARS: '\x03'

After testing several mitigations, the reliable fix/workaround was a hard-exclusive raw /dev/tty keyboard reader inside Codex, bypassing the normal crossterm keyboard polling path for keyboard input in this affected environment.

With that patched path active, Codex receives keyboard input reliably, including ASCII, Enter, Backspace, Ctrl+C, spaces, and UTF-8 characters such as ö, ü, ä, and ß.

Successful patched-run markers:

event_stream.keyboard_source decision=raw_dev_tty_hard_exclusive raw_stdin_keyboard.spawn active=true raw_stdin_keyboard.open_dev_tty ok=true raw_stdin_keyboard.source=/dev/tty event_stream.crossterm_poll_skipped_raw_stdin_keyboard

Successful input evidence:

raw_stdin_keyboard.recv bytes=[97] hex=[0x61] raw_stdin_keyboard.emit code=Char char='a' modifiers=KeyModifiers(0x0) raw_stdin_keyboard.recv bytes=[98] hex=[0x62] raw_stdin_keyboard.emit code=Char char='b' modifiers=KeyModifiers(0x0) raw_stdin_keyboard.recv bytes=[99] hex=[0x63] raw_stdin_keyboard.emit code=Char char='c' modifiers=KeyModifiers(0x0) raw_stdin_keyboard.recv bytes=[49] hex=[0x31] raw_stdin_keyboard.emit code=Char char='1' modifiers=KeyModifiers(0x0) raw_stdin_keyboard.recv bytes=[50] hex=[0x32] raw_stdin_keyboard.emit code=Char char='2' modifiers=KeyModifiers(0x0) raw_stdin_keyboard.recv bytes=[51] hex=[0x33] raw_stdin_keyboard.emit code=Char char='3' modifiers=KeyModifiers(0x0)

UTF-8 evidence after buffering/decoding multibyte sequences:

raw_stdin_keyboard.recv bytes=[195, 182] hex=[0xc3, 0xb6] raw_stdin_keyboard.emit code=Char char='ö' modifiers=KeyModifiers(0x0) raw_stdin_keyboard.recv bytes=[195, 188] hex=[0xc3, 0xbc] raw_stdin_keyboard.emit code=Char char='ü' modifiers=KeyModifiers(0x0) raw_stdin_keyboard.recv bytes=[195, 164] hex=[0xc3, 0xa4] raw_stdin_keyboard.emit code=Char char='ä' modifiers=KeyModifiers(0x0) raw_stdin_keyboard.recv bytes=[195, 159] hex=[0xc3, 0x9f] raw_stdin_keyboard.emit code=Char char='ß' modifiers=KeyModifiers(0x0)

So the issue appears to be in the normal Codex TUI/crossterm keyboard input path in this terminal environment, not in the terminal’s ability to deliver bytes.

What steps can reproduce the bug?

1.Start a RunPod pod/container with Ubuntu 22.04.5 LTS. 2.Open the RunPod JupyterLab web terminal through the RunPod browser/proxy interface. 3.Start Codex CLI v0.125.0 in the terminal: codex 4.Wait until the Codex TUI renders. 5.Type a simple test string into the Codex prompt, for example:

abc123

6.Observe that the Codex prompt/TUI may receive only part of the typed characters, or input becomes unreliable/unusable.

During debugging, I used an instrumented Codex build that logged raw crossterm key events. In failing runs, the received key sequence was incomplete, for example:

RAW KEY CHARS: as COUNT: 2

As a control test, a direct raw /dev/tty probe in the same terminal receives the full abc123 sequence correctly.

Python probe used:

import os, termios, tty

fd = os.open("/dev/tty", os.O_RDWR) old = termios.tcgetattr(fd)

try: tty.setraw(fd) os.write(fd, b"RAW BYTE PROBE active. Type exactly abc123, then Ctrl+C.\r\n")

while True: b = os.read(fd, 16) msg = f"\r\nBYTES: {list(b)} CHARS: {repr(b.decode('utf-8', 'replace'))}\r\n" os.write(fd, msg.encode())

if 3 in b:
    os.write(fd, b"STOP\r\n")
    break

finally: termios.tcsetattr(fd, termios.TCSADRAIN, old) os.close(fd)

That probe receives all characters correctly:

BYTES: [97] CHARS: 'a' BYTES: [98] CHARS: 'b' BYTES: [99] CHARS: 'c' BYTES: [49] CHARS: '1' BYTES: [50] CHARS: '2' BYTES: [51] CHARS: '3' BYTES: [3] CHARS: '\x03'

Mitigations tested that did not fully fix the problem:

disabling cursor position queries disabling foreground/background color queries disabling terminal palette re-query throttling crossterm polling by 15 ms internal raw probes at several TUI lifecycle stages raw stdin reader without hard-exclusive crossterm keyboard bypass

The working approach was a hard-exclusive raw /dev/tty keyboard reader that bypasses the normal crossterm keyboard polling path for keyboard input in this affected environment.

What is the expected behavior?

Codex CLI TUI should reliably receive all typed keyboard input in the RunPod/JupyterLab web terminal.

For example, typing:

abc123

should result in exactly those characters appearing in the Codex prompt.

The TUI should also correctly handle normal editing/control input such as:

Enter Backspace Ctrl+C spaces UTF-8 characters such as ö, ü, ä, and ß

The behavior should match the direct raw /dev/tty probe, which receives all bytes correctly in the same terminal.

Additional information

This was investigated with an instrumented local build of Codex CLI v0.125.0.

Important findings:

The terminal itself can deliver all bytes correctly through /dev/tty. Codex startup and rendering work. The normal Codex TUI/crossterm keyboard path receives only partial keyboard input in this environment. Disabling terminal cursor/color queries did not fully fix the issue. Poll throttling did not fully fix the issue. A hard-exclusive raw /dev/tty keyboard reader did fix input in the affected environment. UTF-8 input works once multibyte sequences are buffered and decoded before emitting KeyCode::Char.

Relevant successful patched-run markers:

safe_terminal_modes active=true safe_terminal_modes disable_focus_change sent safe_terminal_modes disable_bracketed_paste sent safe_terminal_modes disable_mouse_capture sent safe_terminal_modes disable_keyboard_enhancement sent custom_terminal.cursor_query_disabled_by_env terminal_palette.query_foreground_color disabled_by_env terminal_palette.query_background_color disabled_by_env event_stream.keyboard_source decision=raw_dev_tty_hard_exclusive raw_stdin_keyboard.spawn active=true raw_stdin_keyboard.open_dev_tty ok=true raw_stdin_keyboard.source=/dev/tty event_stream.crossterm_poll_skipped_raw_stdin_keyboard

Current root-cause hypothesis:

The issue is likely caused by the normal crossterm event/input path interacting badly with the RunPod/JupyterLab web terminal environment and/or competing reads/terminal queries against the controlling TTY.

Potential fix direction:

Add a fallback keyboard backend for affected terminal environments:

detect or opt into a raw /dev/tty keyboard reader avoid simultaneous crossterm keyboard polling when that backend is active keep crossterm for rendering / non-key events where appropriate decode UTF-8 multibyte input correctly avoid terminal-interactive git credential prompts stealing or contending for /dev/tty

I am not opening a PR because the contributing guidelines say unsolicited PRs are not accepted. I can provide a minimal patch/log bundle if helpful.

codex_tui_v125_runpod_jupyterlab_input_bug_evidence.tar.gz