claude-peers

Peer discovery and messaging network for AI coding agents on the same machine. A shared broker daemon listens on a Unix domain socket (~/.claude/run/claude-peers.sock), backed by SQLite (~/.claude/claude-peers.db), routing messages between Claude Code and Codex CLI sessions.

Claude-to-Claude: prefer Claude Code's native SendMessage / ListAgents (v2.1.224+). Use claude-peers whenever a Codex session is involved.

Native Wake

When a message is sent, the broker wakes the recipient instead of waiting for it to poll:

Client	Wake transport	Endpoint source	Idle session	Busy session
claude-code	Inbox socket (CLAUDE_CODE_MESSAGING_SOCKET + token)	MCP server registers it from its environment	Starts a turn	Reads it between tool calls
codex	codex queue --thread <id>	Codex hook sends session_id to /set-wake	Starts a turn	Receives it after the current turn
cli	none	—	—	—

The wake is a fixed, body-free nudge: [claude-peers] New message from <peer> (<client>, <dir>). Call check_messages to read and reply. On receiving it, call check_messages right away and reply with send_message. check_messages is the only place messages are acknowledged; a message stays unread (and re-deliverable) until then. send_message reports the wake result: queued, coalesced (a wake is already pending), failed, ambiguous, or none.

Turn-Boundary Hooks

~/tools/claude-peers-mcp/hooks/peers-hook.ts --harness claude|codex is the safety net for wakes that fail. It fails open and logs quiet failures to ~/.claude/run/claude-peers-hook.log.

Event	Behavior while messages are unread
Stop	Blocks finishing once: "N unread peer message(s) from X. Call check_messages and reply before finishing."
PreToolUse (Bash)	Before git add/commit/push, adds context to check peer messages first (non-blocking)
UserPromptSubmit	Adds the unread count as context
SessionStart (Codex)	Registers the thread ID for codex queue; reports unread messages

Codex UserPromptSubmit and Stop repeat the thread registration, because Codex SessionStart can run before the MCP server registers.

Workflow Patterns

Task delegation: Send a focused task description to a Codex or Claude peer via send_message. Include file paths, acceptance criteria, and which branch to work on. The broker wakes the receiving agent; no need to promise to poll for its reply.

Code review handoff: After completing work, message a peer with the diff summary and ask for review. The peer can respond with findings via send_message.

Parallel exploration: Multiple agents working the same repo can use set_summary to advertise what they're investigating, preventing duplicate work. Use list_peers with scope repo to see who else is in the same codebase.

Session lifecycle: Use kill_peer to terminate a stuck, unresponsive, or completed peer's agent session. This kills the parent process (e.g., the Codex CLI), not just the MCP subprocess, and cleans up the peer record.

CLI Reference

bun ~/tools/claude-peers-mcp/cli.ts status          # Broker health + all peers (with orphan warnings)
bun ~/tools/claude-peers-mcp/cli.ts peers            # Quick peer listing
bun ~/tools/claude-peers-mcp/cli.ts orphans          # List orphaned server.ts processes (PPID=1)
bun ~/tools/claude-peers-mcp/cli.ts cleanup          # Kill orphaned processes and remove from broker
bun ~/tools/claude-peers-mcp/cli.ts send <id> <msg>  # Send from terminal (tagged as unverified)
bun ~/tools/claude-peers-mcp/cli.ts kill <id>         # Kill a peer's agent session (SIGTERM to parent)
bun ~/tools/claude-peers-mcp/cli.ts kill-broker       # Stop the broker daemon

Message History

check_messages returns recent messages (sent and received), newest first, with enrichment:

• [claude-code] or [codex] client-type tags
• ISO timestamps
• [NEW] marker for unread messages, which the call then acknowledges
• Direction indicator (From/To) with peer summary or CWD

Messages persist across reads — calling check_messages multiple times still shows history. Unread messages survive an MCP server restart: the broker hands them to the agent's new server (same parent process), and a sender's unread messages stay deliverable after it exits.

Orphan Management

MCP server processes detect parent death via stdin close (immediate) and PPID monitoring (30s fallback). The broker's stale-peer sweep (every 30s) also detects orphaned processes (PPID=1) and terminates them.

For manual cleanup: bun cli.ts orphans lists and bun cli.ts cleanup kills orphaned processes.

Gotchas

• Codex sandbox: Codex's macOS seatbelt sandbox blocks socket connect() in workspace-write mode. Codex sessions currently require --dangerously-bypass-approvals-and-sandbox or danger-full-access sandbox to reach the broker. This is a Codex sandbox limitation, not a peers issue — tracked at Codex issue #11095.
• Tool name collision: Claude Code's built-in SendMessage reaches only Claude sessions. To message a Codex peer, call mcp__claude-peers__send_message explicitly — models reach for the built-in first.
• Codex hooks need trust: after installing or changing ~/.codex/hooks.json, run /hooks in Codex and trust the peers-hook.ts entries, or the thread never registers and Codex is not woken.
• Codex wake limits: codex queue does not wake an interrupted or unloaded thread; its hooks report unread messages when it resumes.
• Older Claude Code (no inbox socket): delivery falls back to claude/channel push, which never acknowledges, so the Stop hook blocks once per turn until the agent calls check_messages.
• Claude inbound refused: crossSessionInbound: "refuse" silently drops the wake; the Stop hook still catches unread messages.
• Diagnose a stuck wake: list_peers shows each peer's wake transport and last wake status/time. A wake that was never answered re-arms after 5 minutes.
• Permission allow-list: mcp__claude-peers__send_message may not be in the auto-allow list. The user may need to approve it on first use or add it to settings.json permissions.
• Broker must be running: The broker is managed by launchd (com.minoan.claude-peers-broker). If peers can't connect, check: launchctl list | grep claude-peers.
• Stale socket: If the broker crashes, the socket file persists. On restart, the broker detects and removes it automatically.
• TCP fallback: Set CLAUDE_PEERS_TCP=1 in the broker's env to also listen on TCP port 7899. Clients use TCP when CLAUDE_PEERS_URL is set (e.g., CLAUDE_PEERS_URL=http://127.0.0.1:7899).