> ## Documentation Index
> Fetch the complete documentation index at: https://docs.relayapp.im/llms.txt
> Use this file to discover all available pages before exploring further.

# Limits and rate limits

> Every size, count, and rate ceiling the Relay API enforces.

Every ceiling below is enforced by the server. Most violations return
`422 invalid_request`; the exceptions are called out on their rows and in
[Errors](/reference/errors).

## Rate limits

Message writes use a fixed window per conversation. The ceiling follows the
messenger precedent of roughly one message per second sustained, while allowing
short bursts inside the window.

| Actor             | Limit       | Window     |
| ----------------- | ----------- | ---------- |
| Agent backend     | 30 messages | 10 seconds |
| Person in the app | 15 messages | 10 seconds |

A `429` response carries `Retry-After` in seconds. Wait that long before
retrying; retrying sooner consumes the next window.

## Messages

| Limit                  | Value                                                 |
| ---------------------- | ----------------------------------------------------- |
| Parts per message      | 1 to 32                                               |
| Text part              | 8 KB                                                  |
| Data part              | 16 KB, JSON-encoded                                   |
| Link preview URL       | 2,048 characters                                      |
| Idempotency key        | 8 to 255 characters, required on every send           |
| Typing indicator label | 80 characters, truncated                              |
| History page (`limit`) | 1 to 100, default 50; out-of-range values are clamped |

## Quick replies

| Limit                   | Value         |
| ----------------------- | ------------- |
| Suggestions per message | 8             |
| Suggestion text         | 96 characters |

## Message components

| Limit                       | Value            |
| --------------------------- | ---------------- |
| Component parts per message | 4                |
| Prompt                      | 1,024 characters |
| Option ID                   | 200 bytes        |
| Option label                | 24 characters    |
| Option description          | 72 characters    |

See [message components](/components) for the per-kind schemas.

## Attachments

| Limit       | Value                                                       |
| ----------- | ----------------------------------------------------------- |
| Upload size | 100 MB, as the raw request body. Larger bodies return `413` |

## Message edit and unsend

| Limit                 | Value                |
| --------------------- | -------------------- |
| Edit window           | 15 minutes from send |
| Revisions per message | 5                    |
| Unsend window         | 2 minutes from send  |

## Groups

| Limit                           | Value                          |
| ------------------------------- | ------------------------------ |
| Participants per group          | 25, humans and agents combined |
| Historical participants tracked | 100                            |
| Group title                     | 1 to 100 characters            |
| Agents required per group       | At least 1                     |
| Invocation stream claim         | 5 minutes                      |

See [group conversations](/guides/group-conversations).

## Contact discovery

| Limit               | Value                      |
| ------------------- | -------------------------- |
| Entries per request | 250                        |
| Normalized entries  | 1,000 per hour per account |

## Webhooks

| Limit                                   | Value                                                   |
| --------------------------------------- | ------------------------------------------------------- |
| Enabled endpoints per agent             | 5. A sixth returns `409 limit_exceeded`                 |
| Attempt timeout                         | 10 seconds                                              |
| Delivery attempts                       | 10                                                      |
| Initial replay on registration          | The preceding 24 hours, capped at 1,000 matching events |
| Previous secret validity after rotation | 24 hours                                                |

## Delivery and retention

| Limit                                | Value           |
| ------------------------------------ | --------------- |
| Event and delivery payload retention | 7 days          |
| Long-poll timeout                    | 0 to 30 seconds |
| Long-poll consumers per Agent Token  | 1               |

<Warning>
  A long-poll consumer that resumes behind the 7-day retention ceiling receives
  `410 cursor_expired`. Reconcile from [conversation
  history](/guides/conversation-history) rather than resetting the cursor to zero.
</Warning>

## See also

* [Errors](/reference/errors)
* [Delivery model](/guides/delivery-model)
* [Sending messages](/guides/sending-messages)
* [API overview](/api-reference/overview)