Crate interlink 

Agent-to-agent messaging for Claude Code and Codex CLI.

Claude Code and Codex CLI agents each run an MCP server: outbound is the send_message tool. Claude inbound is delivered by default to a local inbox that a background interlink-mcp wait listener drains (plain claude, no flags), with native notifications/claude/channel push as an opt-in enhancement (interlinked / INTERLINK_CHANNELS=1). A small bus routes messages between agents and buffers for agents that are offline. Codex CLI uses the same protocol and trust gate, with local lifecycle hooks binding the MCP instance to a thread and codex delivering through its queue.

Trust

An agent’s identity is its Ed25519 public key (identity); names are local petnames. Every message is signed, and the channel server verifies the signature and checks the sender against an allowlist before pushing — so an unverified message never reaches the model.

Authority comes from the server’s instructions string, which lands in the host’s MCP context. The peer’s text is untrusted data that parameterises an action; it never authorises one. An ungated channel is a prompt-injection vector.

Pieces (each behind a feature)

• identity — keys, signing, verification, the peer allowlist.
• bus — the broker: per-recipient queues with POST /send, GET /recv.

Modules

agent

The per-agent channel server and its decision logic.

bus

The broker: a durable, keep-until-acked FIFO per recipient over HTTP.

codex

Delivery to an existing local Codex CLI thread through its shared daemon.

delivery

Recoverable host-delivery failures, persisted before releasing a bus message.

identity

Ed25519 identity. The public key is the identity; names are local petnames.

inbox

A restart-safe JSONL inbox with a single reader and atomic cursor updates.

pairing

Durable, session-scoped pairing requests and their control-message outbox.

policy

Per-peer authorization policy: peers.json.

policy_store

Shared peer settings. Readers reload complete snapshots; writers serialize updates.

route

Bus routing addresses.

state

Atomic local state replacement shared by session queues and peer settings.

store

A durable, keep-until-acked FIFO queue — one logical queue per recipient key.

Functions

now_ms

Unix milliseconds.