Show HN: Agent-relay for multi-vendor coding sessions

Let AI coding sessions from different vendors work together, while you stay in charge.

Why

Claude can hand work to Claude on its own. But when you work with sessions from different vendors, such as Codex for planning and review and Claude Code for the code, they can't talk to each other. Without a relay, you're the one transferring context: copying plans, results and reviews between terminals.

agent-relay carries the turns for you. One session leads, the other follows, and the relay passes each turn across, records it on your disk, and stops whenever something needs your decision. It's tested with Claude Code and Codex, and you can extend it to whatever agents you work with by writing an adapter.

These demos use pretend sessions, so they're safe to run anywhere and use no model quota. You need macOS and Python 3.11 or newer.

git clone https://github.com/saranyan/agent-relay.git && cd agent-relay

scripts/console-demo.sh # the web console, with a few pretend sessions scripts/walkthrough.sh # the full two-terminal flow in a temporary folder

With the Claude Code and Codex CLIs installed, run it on real sessions:

export AGENT_RELAY_ROOT=~/relay-root bin/relay init --participants codex claude bin/relay console # [n] launch Codex and Claude Code, [p] pair them, [s] start

The web console tour walks through every screen. The walkthrough shows a recorded run with real message and turn IDs.

The relay coordinates two sessions per team, one turn at a time. It sees each turn from the outside: the turn goes in, the client acknowledges it, and later the client reports it finished. What a session does inside a turn is invisible to the relay. That includes tool loops, subagents and long-running commands.

The full list of guarantees and limits is in the reference.

Ideas the design leaves room for (see the roadmap):

you ──start / pause / answer──┐ ▼ ┌──────────────┐ handoff ┌────────────┐ handoff ┌──────────────┐ │ leader │ ◀──────── │ controller │ ────────▶ │ follower │ │ (Codex) │ ────────▶ │ (fg only) │ ◀──────── │ (Claude) │ └──────────────┘ result └─────┬──────┘ result └──────────────┘ │ durable bus on disk

Bus: an on-disk store of messages and events.

Adapters: they talk to each client. Every capability is explicit, and adapters never invent acknowledgments.

Controller: it runs only in the foreground and keeps exactly one turn in flight. It enforces the budget and the timeout, and stops at every human boundary.

Each turn ends with a small relay block that tells the controller what to do next. Commands, settings and exit codes are in the reference. The specification is in docs/PROTOCOL.md.

Part State

Bus, controller, terminal console, web console Working, covered by the test suite with pretend clients

Discovery of running Claude Code and Codex sessions Working, read-only, on macOS

Codex and Claude Code driving each other (sessions the relay starts) Verified live: Codex 0.163.0 led Claude Code 2.1.310, 2026-10-25

Attaching to an open Codex session, handing an existing session over Built, not yet verified live. Off unless you opt in.

Driving a Claude Code session while it's open in a terminal Not possible. Open sessions are handed over (closed and resumed) instead.

What's needed to get from prototype to dependable is in the roadmap. The details on each client are in integration feasibility.

Document What it covers

Web console tour Every screen of relay serve, with screenshots

Reference Install, consoles, CLI, configuration, guarantees and limits

Walkthrough A recorded two-terminal run

Protocol The specification: root layout, envelopes, state machines, adapter contract

Integration feasibility What real Claude Code and Codex surfaces can and can't do

Context reporting How session titles and summaries are found

Roadmap What's left, and what could come next

Changelog Release notes

Contributing

This is a prototype, and ideas, experiments and pull requests are welcome. See CONTRIBUTING.md for setup and for the stricter rules for changes to the real-client adapters. Report security issues privately through SECURITY.md. This project follows the Contributor Covenant.