biff

Team communication for engineers who never leave the terminal.

Named after the Berkeley dog whose 1980 mail notification program was part of the same BSD family as talk, wall, finger, who, and mesg. Biff resurrects the Unix communication vocabulary as MCP-native slash commands inside Claude Code.

Platforms: macOS, Linux

Quick Start

curl -fsSL https://raw.githubusercontent.com/punt-labs/biff/be375b6/install.sh | sh

Restart Claude Code twice. Type /who to see your team.

Manual install (if you already have uv)

uv tool install punt-biff
biff install
biff doctor

Verify before running

curl -fsSL https://raw.githubusercontent.com/punt-labs/biff/be375b6/install.sh -o install.sh
shasum -a 256 install.sh
cat install.sh
sh install.sh

Features

• MCP-native --- runs inside Claude Code as slash commands, no separate app
• Interactive REPL --- biff launches a terminal client with readline, real-time notifications, and modal talk
• BSD vocabulary --- /who, /write, /talk, /wall --- commands engineers already know
• NATS relay --- cross-machine presence and messaging over encrypted connections
• Agent-first --- agents show up in /who alongside humans, coordinate via /plan and /write
• Status bar --- live unread count, wall broadcasts, talk messages --- wraps your existing status line
• Zero config --- installs in one command, activates per-repo with /biff y

What It Looks Like

See who's online

> /who

▶  NAME    TTY   IDLE  S  HOST       DIR                        PLAN
   @kai    tty1  0:03  +  m2-mb-air  /Users/kai/code/myapp      refactoring auth module
   @eric   tty2  1:22  +  m2-mb-air  /Users/eric/code/myapp     reviewing PR #47
   @priya  tty1  0:00  +  priya-mbp  /Users/priya/code/myapp    writing integration tests

S is message status: + means accepting messages, - means do not disturb.

Send a message

> /write @kai "auth module looks good, just one nit on the error handling"

Message sent to @kai.

Check your inbox

> /read

▶  FROM   DATE              MESSAGE
   kai    Sat Feb 15 14:01  hey, ready for review?
   eric   Sat Feb 15 13:45  pushed the fix for the flaky test
   priya  Sat Feb 15 12:30  can you look at the migration script?

More examples: /finger, /plan, /last, /wall, /talk, /mesg

Check what someone is working on

> /finger @kai

▶  Login: kai                              Messages: on
   On since Sat Feb 15 14:01 (UTC) on tty1, idle 0:03
   Host: m2-mb-air  Dir: /Users/kai/code/myapp
   Plan:
    refactoring auth module

Set your status

> /plan "debugging the websocket reconnect logic"

Plan: debugging the websocket reconnect logic

Bead IDs auto-expand:

> /plan biff-ka4

Plan: biff-ka4: post-checkout hook: update plan from branch

Session history

> /last

▶  NAME    TTY   HOST       LOGIN             LOGOUT            DURATION
   @kai    tty3  m2-mb-air  Sat Feb 22 14:01  still logged in   -
   @kai    tty2  m2-mb-air  Sat Feb 22 11:30  Sat Feb 22 13:58  2:28
   @eric   tty1  m2-mb-air  Sat Feb 22 09:15  Sat Feb 22 12:45  3:30

Broadcast to the team

> /wall "release freeze --- do not push to main" 2h

Wall posted (2h): release freeze --- do not push to main

Every teammate's status bar shows WALL: release freeze in bold red. Expires automatically.

Talk in real time

> /talk @kai "can you review PR #42?"

Waiting for @kai to respond...
Connected to @kai. Type 'end' to return.

BSD-style two-phase handshake: the inviter waits, the target accepts. Messages are ephemeral (NATS core pub/sub, no inbox). Either side types end to hang up.

Go do-not-disturb

> /mesg n

is n

Your status bar shows (n) instead of the unread count. Messages still accumulate --- /mesg y or /read reveals them.

Commands

Command	Origin	Purpose
/write @user "text"	BSD write	Send a message
/read	BSD from	Check your inbox
/finger @user	BSD finger	Check what someone is working on
/who	BSD who	List active sessions
/last	BSD last	Show session login/logout history
/plan "text"	BSD .plan	Set your status
/tty "name"	BSD tty	Name the current session
/talk @user "msg"	BSD talk	Start a real-time conversation
/wall "text"	BSD wall	Broadcast to the team
/mesg y | /mesg n	BSD mesg	Control message reception

CLI

Every slash command has a matching biff CLI command. The CLI works outside Claude Code --- from any terminal, SSH session, or CI script.

Interactive REPL

biff                                       # Launch interactive REPL

biff 0.15.1 — kai:tty1
Commands: finger, last, mesg, plan, read, status, tty, wall, who, write, talk, exit

kai:tty1 ▶ who
▶  NAME    TTY   IDLE  S  HOST       DIR              PLAN
   @kai    tty1  0:00  +  m2-mb-air  /code/myapp      debugging auth
   @eric   tty2  1:22  +  m2-mb-air  /code/myapp      reviewing PR #47
kai:tty1 ▶ talk @eric
Waiting for @eric:tty2 to respond... (type 'end' to cancel)
Connected to @eric:tty2. Type 'end' to return to REPL.

kai:tty1 ▶ can you look at the auth fix?
eric:tty2 ▶ on it now
kai:tty1 ▶ end
Talk with @eric:tty2 ended.
kai:tty1 ▶ exit

The REPL provides a proper session lifecycle (login/logout events, heartbeat, KV presence), readline (history, tab completion), and real-time notifications (wall broadcasts and message alerts appear while you're idle at the prompt). biff with no args is the primary mode; biff who is a shortcut for a one-command session.

Product commands

biff who                                   # List active sessions
biff finger @kai                           # Check what someone is working on
biff write @kai "review the PR"            # Send a message
biff read                                  # Check your inbox
biff plan "debugging websocket reconnect"  # Set your status
biff last                                  # Session login/logout history
biff last @kai --count 10                  # Filter by user, limit results
biff wall "deploy freeze" --duration 2h    # Broadcast to the team
biff wall                                  # Read active wall
biff wall --clear                          # Remove active wall
biff mesg off                              # Go do-not-disturb
biff mesg on                               # Accept messages again
biff tty dev                               # Name this session "dev"
biff status                                # Connection state + unread count
biff talk @kai "can you review?"           # Real-time conversation

Admin commands

biff install                # Install plugin via marketplace
biff enable                 # Activate biff in current repo (creates .biff)
biff disable                # Deactivate biff in current repo
biff doctor                 # Check installation health
biff mcp                    # Start MCP server (stdio, called by plugin)
biff serve                  # Start MCP server (HTTP)
biff uninstall              # Remove plugin and clean up
biff version                # Print version

Global flags

biff --json who             # JSON array of sessions
biff --json status          # JSON object with version, unread, wall
biff --json read            # JSON array of messages
biff --verbose who          # Debug logging to stderr
biff --quiet write @kai "msg"  # Suppress non-JSON output
biff --user github-actions wall "CI failed"  # Identity override for bots

Global flags (--json, --verbose, --quiet, --user) go before the subcommand.

Library API

Commands are also importable as pure async functions:

from biff import commands, CliContext, CommandResult
from biff.relay import LocalRelay

relay = LocalRelay(data_dir)
ctx = CliContext(relay=relay, config=config, session_key="kai:abc123", user="kai", tty="abc123")

result: CommandResult = await commands.who(ctx)
print(result.text)       # Human-readable output
print(result.json_data)  # JSON-serializable data
print(result.error)      # True if command failed

All 10 product commands (who, finger, write, read, plan, last, wall, mesg, tty, status) follow this pattern. See the design log for architecture details.

Setup

Biff requires a git repo and a GitHub identity. Your username and display name are resolved automatically from gh auth --- no manual configuration needed.

Create a .biff file

Commit a .biff file in your repo root (TOML format):

[team]
members = ["kai", "eric", "priya"]

[relay]
url = "tls://connect.ngs.global"

Biff ships with a shared demo relay so your team can start immediately. When you're ready for your own relay, see relay configuration.

biff install registers the MCP server, installs slash commands, and enables the plugin. biff enable activates biff in the current repo and deploys git hooks. Run biff doctor to verify everything is wired up. See Installing for the full guide.

Status Bar

Biff appends to your existing Claude Code status line --- it never replaces it:

Line 1: your-existing-status | kai:tty1(3)
Line 2: ▶ WALL: release freeze until 5pm

Three states: kai:tty1(0) when caught up, kai:tty1(3) (bold yellow) with unreads, kai:tty1(n) when messages are off. Line 2 shows active /talk messages (bold yellow), wall broadcasts (bold red), or an idle marker.

Agents Welcome

Because biff speaks MCP, it does not distinguish between human and agent sessions. An autonomous coding agent can /plan what it's working on, /write a human when it needs a decision, and show up in /who alongside everyone else.

Biff coordinates hybrid teams across two planes:

• Logical plane (cross-machine): /plan shows the task each agent is working on. /who shows all plans across all machines. This prevents duplicate work.
• Physical plane (same-machine): /who shows host and directory per session. When two agents share the same machine and directory, they coordinate via /write and create git worktrees to work in isolation.

See Agent Workflow for patterns and examples.

Vision

Biff assumes the terminal is where you're already working — so that's where your team communication should be. Every command implies intent. There are no channels to monitor, no threads to catch up on, no emoji reactions to parse. Communication is pull-based: you decide when to engage.

Roadmap

Shipped

• Presence: /who, /finger, /plan, /tty, /last
• Messaging: /write, /read, /mesg
• Broadcast: /wall with duration-based expiry
• Real-time: /talk with two-phase handshake and mutual hangup
• NATS relay for cross-machine communication
• Per-project activation (/biff y) with lazy connection management
• Status bar with live unread count, wall, and talk display
• Workflow hooks: plan auto-expand, session lifecycle, git integration
• CLI parity: every MCP tool available as biff <command> with --json output
• Interactive REPL: biff with readline, real-time notifications, modal talk
• Library API: pure async functions for programmatic use and testing
• Notification deferral: ≤2s latency for wall and talk in all states (active and napping)
• Formal verification: Z specifications for talk and REPL, ProB model-checked

Next

Phase	What Ships
Security	E2E encryption (NaCl/libsodium), GitHub identity and auth, per-repo NATS credentials
Real-time	/pair for session sharing with explicit consent
Hosted relay	Managed service with admin controls, audit logs, team isolation

Documentation

Installing | Agent Workflow | Claude Setup | FAQ | Troubleshooting

Design Log | Installer Design | Testing Guide | Changelog | Contributing

Development

uv sync --extra dev        # Install dependencies
make check                 # Run all quality gates (lint, type, test)
make test                  # Tests only (unit + integration)
make lint                  # Lint and format check
make format                # Auto-format code
make help                  # List all targets

License

MIT