@haphazarddev/pi-background-bash

Run explicit background shell jobs from Pi, inspect them through agent tools, and browse their output in Pi's TUI.

Installation

Install from npm:

pi install npm:@haphazarddev/pi-background-bash

Restart Pi after installing or use /reload if the current Pi session supports extension reloads.

Local development

From this repository:

npm install
npm run build
pi install ./extensions/pi-background-bash

To remove the package:

pi remove @haphazarddev/pi-background-bash

Design

The extension leaves Pi's built-in bash tool unchanged. The agent must deliberately call background_bash_start; commands are never moved into the background merely because they run for a long time.

Each job is owned by the current Pi process and records:

• a stable bg-… job ID and operating-system PID
• command, optional human-readable label, and working directory
• start/end timestamps and elapsed time
• running, exited, failed, timed-out, or stopped state
• exit code or terminating signal
• disk-backed stdout/stderr logs

Running jobs receive SIGTERM during Pi shutdown and are force-killed after a short grace period if necessary. On POSIX systems, signals target the complete process group so child processes do not remain behind.

Agent tools

Tool	Purpose
background_bash_start	Start a command and return immediately with its job ID and PID
background_bash_list	List jobs owned by this Pi process
background_bash_status	Read one job's current state and exit metadata
background_bash_logs	Read a bounded page of stdout/stderr log lines
background_bash_stop	Gracefully stop a running job, with force escalation after the grace period

A start call accepts a command, optional human-readable label, optional working directory, optional timeout, and an option controlling whether completion wakes the agent. Labels are trimmed, limited to 80 characters, displayed and searchable in /ps, and preserved in structured list/status results. Ordinary commands should continue to use Pi's built-in bash tool.

TUI

An above-prompt widget shows the newest running command, its theme-colored status, and elapsed time:

 npm run build • running 8s • +1 more • /ps

The default leading glyph is Nerd Font's cod-run_all (U+EB9E) and is rendered in a neutral, dim color. It can be replaced with an ASCII character or hidden through configuration.

When no jobs are running, it shows the most recently completed command with a success, failure, timeout, or stopped color unless that idle state is disabled in configuration.

Open the browser with:

/ps

The browser opens as a focused full-screen process view with a prominent title. Its shortcut bar stays pinned to the bottom while the job list or output fills the available terminal height. Running jobs appear first, newest first, followed by completed jobs newest first; the newest running job is selected when the browser first opens.

Key	View	Action
Ctrl+Alt+K	Prompt	Open the background process browser; configurable
↑ / ↓, j / k	Both	Navigate jobs or output
Enter	Jobs	Open the selected job's output
/	Jobs	Filter live by label, command, job ID, or status; Enter applies and Escape cancels editing
s	Both	Stop the selected running job
d twice	Jobs	Delete the selected completed job and its logs
c twice	Jobs	Clear all completed jobs and their logs
f	Output	Resume following live output after scrolling pauses it
r	Output	Reload the displayed output
g / G	Output	Jump to the beginning or return to the live end (FOLLOWING)
Esc, q	Both	Return to the job list or close the browser

The output view explicitly shows FOLLOWING while tailing live output and PAUSED after scrolling away from the end. The browser continues polling while paused without moving the selected page. Log read/write failures appear as warnings in the output view rather than being silently discarded.

Configuration

Preferences are loaded when the extension starts from:

~/.pi/agent/extensions/pi-background-bash/config.json

The complete default configuration is:

{
  "shortcut": "ctrl+alt+k",
  "widgetIcon": "",
  "completionNotifications": true,
  "showLatestCompleted": true
}

Field	Meaning
shortcut	A usable Pi key identifier accepted by Pi's shortcut dispatcher, such as ctrl+shift+b
widgetIcon	Widget prefix; use "&" for an ASCII fallback or "" to hide it
completionNotifications	Show Pi UI notifications when jobs finish; this does not change per-job notifyAgent wake-up behavior
showLatestCompleted	Keep the latest completed job in the widget while no job is running

Malformed fields fall back independently to their defaults and produce one warning after the Pi UI starts. Use /reload or restart Pi after changing this file.

Permission-system parity

background_bash_start carries shell semantics. If you use @gotgenes/pi-permission-system, add it to shellTools so it receives the same Bash command, path, wrapper, and external-directory checks as Pi's native bash tool:

{
  "shellTools": {
    "background_bash_start": {
      "commandArgument": "command",
      "workdirArgument": "cwd"
    }
  }
}

The global configuration file is normally:

~/.pi/agent/extensions/pi-permission-system/config.json

Without this mapping, the permission extension can only treat the start operation as a generic third-party tool; it cannot apply its full Bash policy.

Logs and ownership

Logs live under a package-owned directory in the operating system's temporary directory. Tool and UI reads are paginated so a large build cannot flood model context or the terminal. Very long or unterminated lines are split into bounded records, each page has a character budget, and sparse byte checkpoints are stored on disk so pagination does not retain one heap offset per output line.

Jobs are session-owned, not durable services. Closing Pi stops running jobs and cleans temporary job state. Use tmux for interactive long-lived processes and launchd/systemd for services that should outlive Pi.

The initial package supports macOS and Linux. Windows installation is blocked until equivalent whole-process-tree cleanup is implemented and tested.

Current scope

The local-testing scaffold intentionally does not include:

• automatic foreground-to-background conversion
• durable jobs that survive Pi
• remote execution
• automatic restarts
• shell history integration

These can be evaluated after the explicit, session-owned workflow has been tested locally.

Development

npm test -- extensions/pi-background-bash/test
npm run typecheck
npm run build
npm pack --workspace extensions/pi-background-bash --dry-run