Hermes Agent

Want Relay as a native channel inside Hermes instead of an ACP bridge? See the Hermes channel plugin.

Message the Hermes Agent already installed on your machine. Relay bridges its hermes acp command. It carries messages, tool activity, and permission cards. Install and authenticate Hermes through its official setup first.

Verify the ACP surface

hermes acp --check

This check must pass before Relay can start.

Pair and start

npm install -g @relaymessenger/cli
relaymessenger pair
relaymessenger start --engine hermes --dir ~/code/my-project

What the bridge carries

The current Hermes ACP server supports:

Capability	Behavior in Relay
Persisted sessions	Load and resume across bridge restarts
Streamed content	Assistant and reasoning content stream over ACP; the bridge sends the finished reply to Relay as one message
Tool activity and diffs	Surface in the conversation
Cancellation	Propagates to Hermes
Plan updates	Surface in the conversation
Permission choices	Arrive as owner-only messages carrying an id; approve or deny by replying `yes <id>` or `no <id>`

How it behaves

Area	Behavior
Hermes keeps its own state	Relay launches `hermes acp` shell-free. Hermes configuration, provider credentials, and `~/.hermes/state.db` stay with Hermes. Relay reads none of them.
Readiness, not version strings	`hermes acp --check` decides whether the local installation can start, rather than an unverified version-string cutoff. The reference implementation audited for this release is Hermes Agent 0.18.2, but the check is what gates startup.
Permission window	Hermes waits 60 seconds for an ACP permission decision. Relay uses a 55-second phone window and denies on timeout or transport failure. The shorter window means Relay always answers Hermes before Hermes gives up.
You own installation and upgrades	Hermes is a binary you install and upgrade yourself through its official setup. The Claude and Codex adapters are pinned inside `relaymessenger` instead.

Troubleshooting

relaymessenger doctor

See integration troubleshooting for the symptoms shared with every other integration. These are specific to this one.

Symptom	Cause and fix
The bridge will not start	Run `hermes acp --check` on its own. If the readiness check fails, fix the Hermes installation: Relay will not start against an installation that reports itself unready.
Approvals are denied without you answering	The 55-second window passed, or the transport failed. Answer sooner, or approve at the keyboard.

Next steps

The relaymessenger CLI for pairing and the approval guarantees
Webhooks for the supported inbound event contract
Claude Code to bridge a second engine from the same computer
Delivery model for webhook acknowledgement and recovery

Start here

Send

Receive

Connect what you already run

Reference

Relay for Business

About Relay

Hermes Agent

What the bridge carries

How it behaves

Troubleshooting

Next steps

​What the bridge carries

​How it behaves

​Troubleshooting

​Next steps

What the bridge carries

How it behaves

Troubleshooting

Next steps