BrynthI/O for AI agents.

Give your agent an address in one command ​

npx brynth init

Brynth is I/O for AI agents: one address to receive, one key to act, one record of everything. init asks for your email, sends you a sign-in link, creates a project, connects Claude Code and Codex with a key each, installs the Brynth skill in the current folder and prints a test webhook. Then ask your agent: "Check my Brynth inbox." See the Quickstart.

From a webhook to an email, with a person in the loop ​

A Stripe webhook reports a failed payment. Your agent writes to the customer, your policy asks you first, you approve on Telegram, the email leaves, and every step is in the ledger.

1. Stripe posts invoice.payment_failed to https://hooks.brynth.ai/w/…. Brynth checks the signature, drops duplicates and queues the event.
2. The agent reads and claims it:

inbox_list({source: "stripe"})
inbox_claim({event_id: "evt_…"})

3. The agent writes to the customer:

email_send({
  to: ["billing@customer.example"],
  subject: "Your payment did not go through",
  text: "Hi, the card on file was declined. You can update it here: …"
})

4. Your policy has this rule, so Brynth asks you before sending:

{
  "rules": [
    { "match": { "tool": "email_send", "to_domain_not_in": ["acme.example"] }, "effect": "require_approval" }
  ]
}

5. Telegram shows you the recipients, the subject and the start of the text, with buttons to approve, deny or ask for more context. You approve within wait_seconds (45 by default), so email_send returns {"status": "queued", "request_id": "req_…", …} and the email leaves from acme@in.brynth.ai. Approve later and email_send returns pending; the email leaves once you approve.
6. The agent closes the event with inbox_ack({event_id: "evt_…", result: "Reminder sent"}).
7. The ledger has every step, each with who did it and when: ledger_query({subject: "evt_…"}) shows the event, ledger_query({subject: "req_…"}) the request and your decision, and a query on the message_id (msg_…) of an entry in the messages that email_send returns shows that email. ledger_verify() checks that nothing was changed afterwards.

The customer's reply comes back to the same inbox as an email.received event.

What is in the box ​

• Inbox: webhooks and email with one envelope, deduplication, leases and retries.
• Requests and policy: approvals and questions by email or Telegram, rules for what needs a person.
• Disk: key-value, files and task state per project.
• Email sending from your project's address.
• Ledger: a hash-chained record of every effect.

Brynth runs in the EU. The CLI and the skill are open source under the MIT License. Agents can read these docs as Markdown: start from llms.txt.