opencode-pty

A plugin for OpenCode that provides interactive PTY (pseudo-terminal) management, enabling the AI agent to run background processes, send interactive input, and read output on demand.

Why?

OpenCode's built-in bash tool runs commands synchronously—the agent waits for completion. This works for quick commands, but not for:

• Dev servers (npm run dev, cargo watch)
• Watch modes (npm test -- --watch)
• Long-running processes (database servers, tunnels)
• Interactive programs (REPLs, prompts)

This plugin gives the agent full control over multiple terminal sessions, like tabs in a terminal app.

Features

• Background Execution: Spawn processes that run independently
• Multiple Sessions: Manage multiple PTYs simultaneously
• Interactive Input: Send keystrokes, Ctrl+C, arrow keys, etc.
• Output Buffer: Read output anytime with pagination (offset/limit)
• Pattern Filtering: Search output using regex (like grep)
• Permission Support: Respects OpenCode's bash permission settings
• Session Lifecycle: Sessions persist until explicitly killed
• Auto-cleanup: PTYs are cleaned up when OpenCode sessions end

Setup

Add the plugin to your OpenCode config:

{
  "$schema": "https://opencode.ai/config.json",
  "plugin": ["opencode-pty"]
}

That's it. OpenCode will automatically install the plugin on next run.

Updating

Warning

OpenCode does NOT auto-update plugins.

To get the latest version, clear the cached plugin and let OpenCode reinstall it:

rm -rf ~/.cache/opencode/node_modules/opencode-pty
opencode

Tools Provided

Tool	Description
pty_spawn	Create a new PTY session (command, args, workdir, env, title)
pty_write	Send input to a PTY (text, escape sequences like \x03 for Ctrl+C)
pty_read	Read output buffer with pagination and optional regex filtering
pty_list	List all PTY sessions with status, PID, line count
pty_kill	Terminate a PTY, optionally cleanup the buffer

Usage Examples

Start a dev server

pty_spawn: command="npm", args=["run", "dev"], title="Dev Server"
→ Returns: pty_a1b2c3d4

Check server output

pty_read: id="pty_a1b2c3d4", limit=50
→ Shows last 50 lines of output

Filter for errors

pty_read: id="pty_a1b2c3d4", pattern="error|ERROR", ignoreCase=true
→ Shows only lines matching the pattern

Send Ctrl+C to stop

pty_write: id="pty_a1b2c3d4", data="\x03"
→ Sends interrupt signal

Kill and cleanup

pty_kill: id="pty_a1b2c3d4", cleanup=true
→ Terminates process and frees buffer

Configuration

Environment Variables

Variable	Default	Description
PTY_MAX_BUFFER_LINES	50000	Maximum lines to keep in output buffer per session

Permissions

This plugin respects OpenCode's permission settings for the bash tool. Commands spawned via pty_spawn are checked against your permission.bash configuration.

{
  "$schema": "https://opencode.ai/config.json",
  "permission": {
    "bash": {
      "npm *": "allow",
      "git push": "deny",
      "terraform *": "deny"
    }
  }
}

Important

Limitations compared to built-in bash tool:

• "ask" permissions are treated as "deny": Since plugins cannot trigger OpenCode's permission prompt UI, commands matching an "ask" pattern will be denied. A toast notification will inform you when this happens. Configure explicit "allow" or "deny" for commands you want to use with PTY.

• "external_directory" with "ask" is treated as "allow": When the working directory is outside the project and permission.external_directory is set to "ask", this plugin allows it (with a log message). Set to "deny" explicitly if you want to block external directories.

Example: Allow specific commands for PTY

{
  "$schema": "https://opencode.ai/config.json",
  "permission": {
    "bash": {
      "npm run dev": "allow",
      "npm run build": "allow",
      "npm test *": "allow",
      "cargo *": "allow",
      "python *": "allow"
    }
  }
}

How It Works

1. Spawn: Creates a PTY using bun-pty, runs command in background
2. Buffer: Output is captured into a rolling line buffer (ring buffer)
3. Read: Agent can read buffer anytime with offset/limit pagination
4. Filter: Optional regex pattern filters lines before pagination
5. Write: Agent can send any input including escape sequences
6. Lifecycle: Sessions track status (running/exited/killed), persist until cleanup

Session Lifecycle

spawn → running → [exited | killed]
                      ↓
              (stays in list until cleanup=true)

Sessions remain in the list after exit so the agent can:

• Read final output
• Check exit code
• Compare logs between runs

Use pty_kill with cleanup=true to remove completely.

Local Development

git clone https://github.com/shekohex/opencode-pty.git
cd opencode-pty
bun install
bun run tsc --noEmit  # Type check

To load a local checkout in OpenCode:

{
  "$schema": "https://opencode.ai/config.json",
  "plugin": ["file:///absolute/path/to/opencode-pty"]
}

License

MIT

Contributing

Contributions are welcome! Please open an issue or submit a PR.

Credits

• OpenCode - The AI coding assistant this plugin extends
• bun-pty - Cross-platform PTY for Bun