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PTY output pollutes OpenCode session with ANSI escape sequences, breaking keyboard input on resume

Abierto
  • ¿Algo no está bien?
#75 0 comentarios 0 reacciones 0 asignados Ver en GitHub

Los mantenedores suelen responder en 1 día

@NAnD71 ya está trabajando en esto.

Desde el 5/10/2026.

  • #76 de @NAnD71 — abierto

Evaluación

Dificultad
4/5
Tiempo estimado
3-5 días
Aptitud para principiantes
30/100
Tipo de issue
Error
Claridad
Bien especificado
Estado de actividad
Estancado
Stack tecnológico
sqlite, typescript
Área
cli, developer-experience

Línea de trabajo

Start by tracing the pty_read results and pty_exited notifications that write PTY output into the session; the issue does not name specific files or tests. Check how sanitizing those messages can leave the raw buffer untouched, and verify that ANSI/VT sequences no longer execute when a session is reopened while the Web UI / xterm.js stream remains raw.

Escrito por el modelo de indexación a partir del texto del issue.

Descripción

Hi,

I ran into a really confusing issue where resuming an old OpenCode session made the TUI basically unusable — arrow keys, delete, and shortcuts stopped working, and the screen kept getting cleared/redrawn in weird ways.

The problem in one sentence: pty_read results and <pty_exited> notifications write raw PTY output (including ANSI/VT escape sequences) directly into the OpenCode session, and the TUI re-executes those sequences every time it renders the message.

Real impact

  • Sessions that output terminal-mode sequences like ESC[?9001h, ESC[?1004h, ESC[?25l, ESC[2J, or ESC]0;... permanently poison the chat history.
  • Every time you open, resume, or fork the session, the TUI re-runs the sequences. In my case this meant the screen was cleared and the keyboard input mode was switched, so arrow keys / delete / shortcuts stopped working (typing via the IME still worked, which made it extra confusing).
  • New sessions and unrelated sessions are fine; only the poisoned session is affected. Forking copies the bad messages, so the fork is also broken.

Reproduction
The simplest repro is to spawn anything that prints a terminal-mode sequence and then read or resume the session:

pty_spawn: command="printf", args=["\x1b[?9001h\x1b[?25ldone\n"], description="ansi repro"
pty_read: id=<pty-id>

After the pty_read returns, close and reopen the session. The TUI will re-execute ESC[?9001h and ESC[?25l when it renders that message.

A more realistic trigger is running a Playwright test suite or anything that uses a TTY-aware tool under a pseudo-terminal — the PTY gets the raw sequences, and they end up in opencode.db unchanged.

Environment

  • Windows 11 + Windows Terminal
  • opencode 1.18.34
  • opencode-pty 0.4.0

Workaround
I confirmed the cause by finding parts in opencode.db that contain \u001b and replacing the escape byte with visible text:

sqlite3 ~/.local/share/opencode/opencode.db "UPDATE part SET data = replace(data, '\u001b', '[ESC]') WHERE data LIKE '%\u001b%';"

After that, the affected session resumed normally.

Suggested fix
Sanitize ANSI/VT escape sequences (CSI, OSC, and stray ESC) before writing PTY output into pty_read results or <pty_exited> notifications. The raw buffer can stay untouched so the Web UI / xterm.js stream still works. A config option (e.g. PTY_SANITIZE_OUTPUT=false) to keep raw output would be nice for debugging.

Lenguaje dominante
TypeScript
Estrellas
594
Forks
61
Merge medio
1 d 20 h
PR fusionados (30 d)
3

Preparar el entorno

Este proyecto no incluye contenedor de desarrollo, Dockerfile ni guía de contribución, así que la configuración corre por tu cuenta: empieza por su README y consulta nuestra guía para la primera contribución para los pasos generales.

Primeros pasos

  1. Lee el issue completo y luego la guía de contribución del proyecto.
  2. Comenta en el issue que vas a ocuparte — evita que dos personas hagan lo mismo.
  3. Haz un fork del repositorio y trabaja en una rama.
  4. Abre un pull request que haga referencia al número del issue.

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