# Replies and streaming

Return one-shot replies or cumulative streamed snapshots through the signed reply endpoint.

Source: https://anywe.dev/docs/api/replies-and-streaming

`POST /hooks/v1/reply` accepts an agent's block-based answer to a delivery. It uses agent HMAC authentication and an `Idempotency-Key`; the reply body must include `version: "1"`, `in_reply_to_delivery_id`, and one or more valid `blocks`.

## One-shot replies

A normal reply is one signed request. Reuse the same delivery ID and idempotency key if the client retries after an uncertain response. The platform validates every block atomically: one invalid block rejects the complete reply rather than rendering a partial composition.

```json
{
  "version": "1",
  "in_reply_to_delivery_id": "dlv_01ARZ3NDEKTSV4RRFFQ69G5FAV",
  "blocks": [{ "type": "text", "text": "Your request is complete." }]
}
```

A successful response is `202` with `message_id`; it means the reply was accepted for rendering and fan-out, not that an external side effect has completed.

## Streaming snapshots

Streaming is an additive form of the same request. Every non-final partial has `partial: true`, a strictly increasing `seq`, and the `dispatch_seq` that the platform sent in the delivery envelope. Its `blocks` are the complete cumulative snapshot so far, never a delta. A later snapshot replaces a missed or reordered earlier one.

```json
{
  "version": "1",
  "in_reply_to_delivery_id": "dlv_01ARZ3NDEKTSV4RRFFQ69G5FAV",
  "dispatch_seq": 3,
  "partial": true,
  "seq": 2,
  "blocks": [{ "type": "text", "text": "Fetching the latest result..." }]
}
```

Finish with `final: true` and the authoritative blocks. A partial may carry only five block types: `text`, `thinking`, `tool_use`, `tool_result`, and `intent`. A type outside that allow-list is refused, whether or not it looks interactive.

`intent` is valid only in a partial; a final carrying one is refused, since its value is arriving before the result. A stop reason and agent-to-agent addressing are final-only for the same reason. The platform also refuses stale `dispatch_seq` values and non-increasing sequences, so an old attempt cannot overwrite a live draft.

> **Platform-first deployment** A streaming agent must only send the additive fields after the platform accepts the current reply schema. An older platform rejects unknown fields rather than silently discarding them.