@chensl/pi-unified-exec

Codex-style unified_exec for pi: long-running shell sessions that the model starts, polls, and drives with write_stdin, instead of one blocking bash call per command.

pi install npm:@chensl/pi-unified-exec

Use pi install -l npm:@chensl/pi-unified-exec to install for the current project only.

What the model can do

pi's built-in bash runs a command to completion. With this extension the model can also:

• run a dev server, test watcher, or long build, get its session ID back after the first few seconds, and poll for new output while it keeps working
• drive a REPL, ssh, a debugger, or any prompt-driven program with tty: true, writing input and keystrokes such as Ctrl-C (\u0003) to the running process
• stop waiting on a slow command (cancel write_stdin) while it keeps running in its session

A typical exchange:

exec_command  {cmd: "npm run dev", yield_time_ms: 5000}
  -> Process running with session ID 3 ...        (server is up, output so far)
write_stdin   {session_id: 3}                       (poll for new output later)
write_stdin   {session_id: 3, chars: "\u0003"}      (Ctrl-C; needs tty: true)
  -> Process exited ...                            (the server stopped)

Tool names, parameters, and result text follow Codex, so prompts written for Codex's unified_exec carry over. The runtime is native Rust and runs on Linux, macOS, and Windows. It keeps output and session counts bounded, and terminates the process group (Unix) or Job Object (Windows) of its sessions when pi shuts down.

Commands use $SHELL on Unix and PowerShell on Windows. No additional configuration is needed.

Starting a new session, reloading extensions, or exiting pi terminates processes started by the extension. Hosts that never emit session_shutdown keep a lazily created runtime until the process exits. It runs with the same permissions as pi and does not add a sandbox or approval prompts.

Output and cancellation

• Output is incremental: each call returns only the output consumed during that call.
• Native buffering retains at most 1 MiB per session between polls, keeping the beginning and end. Tool results and live previews also keep bounded head/tail output (up to 50,000 bytes and approximately 2,000 lines, plus omission/status notices).
• Truncation reports the original size, including bytes omitted by the native runtime. Omitted output is not saved to disk and cannot be recovered by expanding the tool. Redirect a command's output to a file when you need a complete log.
• Cancelling exec_command terminates its process and returns captured output, including the bounded termination drain. Cancelling write_stdin stops waiting but leaves the session available. Both return cancelled: true when cancellation interrupts an active wait; a surviving session is identified by session_id.
• Cancelling a queued call or passing invalid parameters does not send input. Interactions with the same session are serialized.
• With tty: true, Ctrl-C is sent through the terminal to its foreground job. Without a PTY, Ctrl-C interrupts the process group on Unix and terminates the process/job on Windows. Like Codex, commands without a PTY run with stdin closed; use tty: true for interactive input.

Collapsed tools show a short command preview and the last five visual output lines. Expanding reveals the full command and all retained output, not omitted output. Nonzero exits and cancellations use pi's error result status without dropping structured output.