$ cat ~/map/pier.md

Pier

macOS desktop client for pi: streams sessions over pi --mode rpc with diffs, follow-ups, and extension dialogs.

tools✓ Sep 12

Download the Pier DMG (ad-hoc signed; the app updates itself automatically)

## TL;DR

A macOS desktop GUI client for the pi coding agent that spawns pi --mode rpc per session, streaming transcripts with inline diffs, a composer with follow-up promotion to steering, and extension dialogs rendered as sheets.

## Key points

• $Uses the pi installation you already have: one pi --mode rpc process per open session, so models, settings, extensions, and slash commands behave as in the terminal, and any session can be resumed with pi -c.
• $Lists every project pi has run in, derived from ~/.pi/agent/sessions, with sessions grouped under each project and unread / needs-input markers in the sidebar plus a Dock badge.
• $Streams the transcript with markdown, collapsed thinking, tool calls with live output, and inline edit diffs; the composer offers / commands, @ file mentions, image paste, and ArrowUp history, with follow-ups queued while a turn runs and promotable to steering.
• $Shows model and thinking-level pickers, a context meter, status text from extensions, the current git branch, and a read-only diff of the working tree against HEAD refreshed as files change, plus a login shell in the project directory.
• $Requires macOS on Apple silicon and pi 0.85 or newer on PATH; app-only preferences live in ~/.pi/gui/settings.json while everything else stays in pi's own configuration.

## FAQ

## References

• README ↗

Last updated: Sep 12, 2026