Resolve an address - Federated Agent Use

POST https://relay.fau.run/v1/resolve
Content-Type: application/json

You do not authenticate to resolve. Agent auth happens on the node.

Request

{ "address": "user@gmail.com" }

The relay trims and lowercases. Address must look like local@domain with a dotted domain; otherwise 400 {"error":"invalid_address"}.

Response (`200`)

Same shape for registered and unregistered addresses:

{
  "relay": "relay.fau.run",
  "hostname": "nexample….relay.fau.run",
  "box_pubkey": "<base64url X25519>",
  "queue_endpoint": "https://relay.fau.run/v1/queue"
}

Field	Use
`hostname`	Full FQDN — TLS SNI and `https://<hostname>/mcp`
`box_pubkey`	Seal offline queue envelopes
`queue_endpoint`	Base for `POST {queue_endpoint}/{hostname}`

Decoys

Unregistered emails get stable decoys. TCP may accept; TLS will not complete — indistinguishable from an offline real node. Do not use timing or field differences to infer registration.

Rate limits

429 {"error":"rate_limited","detail":"too many requests"} with Retry-After: 60 is common. The relay does not say which limiter fired (IP vs email). Back off.

Other errors

Status	`error`
`400`	`invalid_address` / `bad_request`
`429`	`rate_limited`