pi-peer

Peer-to-peer chat between Pi coding-agent sessions that share a room — their Herdr workspace, or a shared folder room under Paseo. Two independently running sessions can find each other, read each other's recent history, and send each other messages.

It is symmetric, natural chat between equal agents — not RPC or task delegation to a subagent. There is no request/response correlation, no timeoutMs, no waiting, and no <peer_pong>. Three tools, nothing else.

Features

• talk_to — send a message to another live session (target = public peer id peer-xxx or unique display name). Returns delivery confirmation only; a reply, if any, simply arrives later as a new <peer_message>.
• talk_sessions — list live peers, one per line: <peer-id> <name> <status> with idle | working | blocked | done | unknown, (current) marker, and (N queued) for pending inbound. Every session gets a stable friendly pet name, unique per room.
• talk_latest — read a peer's N most recent completed conversation events (count 1–10, default 1). Peers publish a bounded history only — thinking and live turns are never shared.
• No daemon. Peers coordinate through an atomic file mailbox in the agent directory.
• Send-only semantics. talk_to never blocks waiting for a response; the language of the conversation is handled by the agents replying with another talk_to in the opposite direction.
• Never misses a message. A busy receiver is steered mid-turn; an idle receiver is triggered with a fresh turn. A message that fails to inject is requeued, and orphaned claims are reclaimed on startup.
• Private by default. Thinking is never published, and no session ever reads another session's transcript.

How it works

                   Herdr workspace (the "room")
    ┌────────────────┐                    ┌────────────────┐
    │  Pi session A  │                    │  Pi session B  │
    │    peer-a1b    │                    │    peer-c3d    │
    └───────┬────────┘                    └───────▲────────┘
            │                                     │
            │ talk_to(target="peer-c3d")          │ arrives as a <peer_message>
            │   = enqueue + confirm               │   user message (idle trigger)
            ▼                                     │   or steer (busy)
    ┌───────────────────────────────────────────────────────┐
    │       <agent-dir>/pi-peer/talk/<room-id>/             │
    │    sessions/   inbox/                          latest/ │
    └───────────────────────────────────────────────────────┘
            ▲                                     │
            │  B replies with talk_to to          │  B's reply is a new
            │  peer-a1b — also idle-triggered     │  <peer_message>
            │  or steered                          ▼
            └────────────────────────────────────────────────

Each session registers itself, heartbeats every 10 s, and polls its own mailbox. There is no central process to run. The "room" is normally just the Herdr workspace the session runs in — under Paseo, pi-peer makes one shared room per folder instead (see below), so every agent in the same folder meets there.

A message is delivered to an idle receiver as a normal user message (trigger behavior) and to a busy receiver as a steer (deliverAs: "steer") straight into its running turn — regardless of who sent it. A reply is simply another talk_to in the opposite direction, so whichever side is idle gets triggered and whichever is busy gets steered. Nothing ever waits for a turn boundary to lose a message.

Requirements

• Pi coding agent and a running Herdr server — both required. Two ways to give a session its identity: run pi inside a herdr pane (the pane hands it HERDR_ENV=1, HERDR_PANE_ID, HERDR_SOCKET_PATH), or let Paseo spawn the agent — pi-peer then sets those up itself (it just needs the herdr CLI on PATH and the server socket reachable).
• Optional: the Paseo daemon, if you want to spawn agents headlessly or from other devices. The classic "pi inside a herdr pane" setup doesn't need it.
• Node 22.19+ for development (required by the Pi coding-agent SDK).

Paseo integration

A Paseo-spawned agent only gets PASEO_AGENT_ID + PASEO_AGENT_CWD — no HERDR_* — so pi-peer builds the context itself:

• One folder = one room — a shared Herdr workspace named after the folder (not paseo's per-conversation workspace id, which would split agents sharing a checkout). A workspace you already opened for that folder is adopted instead of duplicated.
• One tab per agent, remembered per paseo agentId — a reload takes its tab back: same identity, same mailbox, no duplicates.
• Panes join too — a hand-run pi session in a herdr pane inside that folder sees the same room. Panes join, never create.
• Housekeeping — on start, each agent closes rooms of folders with no live paseo agent and removes tabs of deleted agents. Adopted workspaces are never closed, only their agent tabs. No trustworthy listing = no cleanup.
• Degrades quietly — provisioning failure means one log line and a session without peer talk; pi always starts.

Running headless

Paseo-spawned agents need a herdr server they can reach: the herdr CLI on PATH and its socket at ~/.config/herdr/herdr.sock (any open herdr window provides the socket too). On a daemon machine, run herdr server next to the paseo daemon.

Paseo agents inherit the daemon's environment, and service managers give you a minimal PATH — so the reliable pattern is one small wrapper script that pins PATH, starts herdr server if needed, then execs the paseo daemon. Save it as ~/bin/paseo-daemon.sh (chmod +x, adjust paths):

#!/bin/sh
# Paseo daemon + herdr server launcher for service managers.
# Pin PATH: launchd/systemd units see a minimal environment, so point at
# wherever node, paseo, and herdr actually live.
export PATH="$HOME/.local/bin:/usr/local/bin:/opt/homebrew/bin:/usr/bin:/bin"
export HOME="${HOME:-$(cd ~ && pwd)}"

# Herdr headless server: needed by pi-peer's provisioning (its socket is the
# API). Idempotent — skip when any herdr instance already owns the socket
# (e.g. an open herdr window).
if [ ! -S "$HOME/.config/herdr/herdr.sock" ]; then
  nohup herdr server >>"$HOME/.local/share/herdr-server.log" 2>&1 &
fi

# No HERDR_* here on purpose: agents must self-provision via pi-peer.
exec paseo daemon start --foreground

macOS — ~/Library/LaunchAgents/local.paseo-daemon.plist pointing at that script:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
  <key>Label</key>
  <string>local.paseo-daemon</string>
  <key>ProgramArguments</key>
  <array>
    <string>/bin/sh</string>
    <string>-lc</string>
    <string>exec "$HOME/bin/paseo-daemon.sh"</string>
  </array>
  <key>RunAtLoad</key>
  <true/>
  <key>KeepAlive</key>
  <true/>
  <key>StandardOutPath</key>
  <string>/tmp/paseo-daemon.log</string>
  <key>StandardErrorPath</key>
  <string>/tmp/paseo-daemon.log</string>
</dict>
</plist>

launchctl load ~/Library/LaunchAgents/local.paseo-daemon.plist

Linux — ~/.config/systemd/user/paseo-daemon.service running the same script:

[Unit]
Description=Paseo daemon (+ herdr server)
After=default.target

[Service]
ExecStart=%h/bin/paseo-daemon.sh
Restart=on-failure
RestartSec=3

[Install]
WantedBy=default.target

systemctl --user daemon-reload
systemctl --user enable --now paseo-daemon
loginctl enable-linger "$USER"   # keep it running without a login session

If you only need herdr (no paseo), the same units work with ExecStart/ProgramArguments pointing straight at herdr server. On multi-seat boxes, scope the units per user.

Install

pi install npm:@sting8k/pi-peer

Or from GitHub:

pi install git:github.com/sting8k/pi-peer

Tools register automatically when a Pi session starts inside a Herdr pane or as a Paseo-spawned agent. Set PI_PEER_DISABLED=1 for sessions that must not appear as peers or receive requests, and PI_CODING_AGENT_DIR to override the agent directory (default ~/.pi/agent).

Migrating from the pi-roo extension, which used to bundle these tools: set features.talk=false in your pi-roo config, install pi-peer, then reload every Pi session. The storage namespace changed (pi-roo/talk → pi-peer/talk), so the cutover is a clean break with no dual-read migration.

Guarantees

Guarantee	Rule
Liveness decides delivery	Registrations (refreshed every 10 s) are the authoritative signal. Clean shutdown fails talk_to immediately; a crash fails it once the registration goes stale (~1 min + two confirming checks). Dead peers cannot be listed or targeted.
Durable, at-least-once mailbox	Atomic writes (temp file + rename). Messages are claimed via a .processing rename and held through the turn, consumed at agent_end; failed injections requeue, and orphaned claims are reclaimed on reload/rebind/startup. Host-lifecycle guarantee — not proof the model consumed the message.
Fair, serial delivery	One message per poll tick, oldest first (per-runtime filename order). An idle receiver gets a fresh turn; while that turn is engaging, a burst steers into it instead of overlapping. Busy receivers are steered regardless of sender. No same-caller restriction, no batching, no routing.
A reply is another talk_to	No agent_end auto-reply, no <peer_pong>, no waiters. The conversation is carried by plain <peer_message> inbound messages.
Ambiguity fails closed	Two peers sharing a public id resolve to an error, never to a guess.

For the full flow, invariants, and cleanup rules, see docs/ARCHITECTURE.md.

Storage

Artifacts live under <agent-dir>/pi-peer/talk/<room-id>/ (the workspace, or the provisioned folder room under Paseo):

Path	Contents
sessions/	Peer registrations, refreshed by heartbeat.
inbox/	Queued chat messages per target session.
latest/	Each peer's published history.

Writes are atomic (temp file plus rename) and the mailbox directory is created with 0700 permissions. Artifacts of dead sessions are collected after a 24 h TTL.

Development

npm install
npm test                  # 61 tests (5 suites)
npm run test:focused      # 55 peer tests
npm run test:integration  # 6 mocked two-peer lifecycle tests
npm run typecheck         # tsc --noEmit

• pi-extension/pi-peer/ — shipped runtime: index.ts (entrypoint), service.ts (tool registration), schemas.ts, herdr.ts (workspace identity), history.ts, protocol.ts (chat envelopes), storage.ts (atomic persistence).
• test/peer/ — unit tests. test/integration/ — mocked two-peer lifecycle.
• docs/ — architecture and decisions; see docs/decisions/0011-standalone-pi-peer-extension.md for the packaging decision.

Distribution is available from both npm and GitHub. The npm package is published publicly as @sting8k/pi-peer.

Related Work

• Pi coding agent — the host whose extension API this builds on.
• Herdr — the pane/workspace environment that provides session identity and peer discovery.

License

MIT