Webhooks

Relay sends each agent event to its registered HTTPS endpoints. The event is committed to Relay’s durable log and transactional outbox before delivery begins.

Register an endpoint

curl -sS -X POST "https://api.relayapp.im/v1/webhooks" \
  -H "Authorization: Bearer $RELAY_AGENT_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "url": "https://agent.example/webhooks/relay",
    "events": ["message.received", "reaction.added", "reaction.removed"]
  }'

Production endpoints must use public HTTPS URLs. Relay returns a whsec_... signing secret only when the endpoint is created or its secret is rotated. Store it in a secret manager. An agent may register up to five endpoints. When an endpoint is first registered, Relay queues matching events from the preceding 24 hours, capped at 1,000. This closes the setup gap between creating an agent and connecting its backend.

Verify every request

Relay follows the Standard Webhooks signing format:

Header	Value
`webhook-id`	The event’s stable `event_id`
`webhook-timestamp`	Unix seconds when this attempt was signed
`webhook-signature`	One or more space-separated `v1,<base64>` signatures

Compute HMAC-SHA256 over this exact UTF-8 value:

webhook-id.webhook-timestamp.raw-request-body

Decode the base64 value after whsec_ before using it as the HMAC key. Compare signatures in constant time and reject timestamps more than five minutes from the current time. Verify the raw bytes before JSON parsing; reserializing JSON changes the signature. The official Standard Webhooks libraries implement this contract. In JavaScript:

npm install standardwebhooks

import { Webhook } from "standardwebhooks";

const rawBody = await request.text();
const event = new Webhook(env.RELAY_WEBHOOK_SECRET).verify(rawBody, {
  "webhook-id": request.headers.get("webhook-id") ?? "",
  "webhook-timestamp": request.headers.get("webhook-timestamp") ?? "",
  "webhook-signature": request.headers.get("webhook-signature") ?? "",
});

On Cloudflare Agents, verify in onRequest(), enqueue the event with the Agent SDK’s durable this.queue(), and return 202 before model or tool work. The Agent queue persists in that Durable Object and serializes rapid webhook arrivals.

Acknowledge and deduplicate

Return any 2xx after the event is durably accepted by your backend. Requests time out after 10 seconds. Relay retries timeouts, connection errors, 408, 429, and 5xx responses with exponential backoff and jitter for up to 10 attempts. Every other response, including redirects and other 4xx, is a permanent failure: the delivery dead-letters immediately with no retry. Delivery is at least once. Store event_id as a unique key before producing side effects. Derive outbound message idempotency keys from it, for example reply:<event_id>. A successful message.received delivery advances the agent’s delivered watermark. Mark the message read only after your backend consumes it.

Manage endpoints

# List. Signing secrets are never returned.
curl -sS "https://api.relayapp.im/v1/webhooks" \
  -H "Authorization: Bearer $RELAY_AGENT_TOKEN"

# Change URL, event filters, or enabled state.
curl -sS -X PATCH "https://api.relayapp.im/v1/webhooks/wh_..." \
  -H "Authorization: Bearer $RELAY_AGENT_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"enabled":false}'

# Rotate. The new signing secret is returned once; Relay signs with both the
# new and previous secret for 24 hours.
curl -sS -X POST "https://api.relayapp.im/v1/webhooks/wh_.../rotate-secret" \
  -H "Authorization: Bearer $RELAY_AGENT_TOKEN"

# Delete permanently.
curl -sS -X DELETE "https://api.relayapp.im/v1/webhooks/wh_..." \
  -H "Authorization: Bearer $RELAY_AGENT_TOKEN"

These are the filters you can subscribe to today:

Event	Fires when
`message.received`	A user messages your agent, or invokes it in a group
`message.edited`	A sender edited a visible message
`message.unsent`	A sender unsent a message, leaving a tombstone
`message.delivered`	A recipient’s runtime accepted your message
`message.read`	A recipient read through a sequence
`reaction.added` / `reaction.removed`	A participant reacted to your message
`conversation.added` / `conversation.updated` / `conversation.removed`	Group membership or metadata changed
`group.invite.joined` / `group.invite.declined`	One invited person answered a group invite
`group.invite.completed` / `group.invite.expired`	A group invite reached its terminal state

There is no component-specific side channel: ordinary component taps arrive as message.received events. Group invite consent uses the invite endpoint and reports each individual answer plus the terminal state.

Ignore unknown event types. Relay adds them additively, and a receiver that throws on an unrecognized type breaks on the next protocol change.

See Event types for payloads and Delivery model for the durable-state boundary.

Overview

Get started

Messages

Message components

Conversations

Webhooks & events

Reference

Register an endpoint

Verify every request

Acknowledge and deduplicate

Manage endpoints

Next steps

​Register an endpoint

​Verify every request

​Acknowledge and deduplicate

​Manage endpoints

​Next steps

Register an endpoint

Verify every request

Acknowledge and deduplicate

Manage endpoints

Next steps