---
summary: "Rich output protocol for structured media, embeds, audio hints, and replies"
read_when:
  - Changing assistant output rendering in the Control UI
  - Debugging `[embed ...]`, structured media, reply, or audio presentation directives
title: "Rich output protocol"
---

Assistant output can carry a small set of delivery/render directives:

- structured `mediaUrl` / `mediaUrls` fields for attachment delivery
- `[[audio_as_voice]]` for audio presentation hints
- `[[reply_to_current]]` / `[[reply_to:<id>]]` for reply metadata
- `[embed ...]` for Control UI rich rendering

Remote media attachments must be public `https:` URLs. Plain `http:`,
loopback, link-local, private, and internal hostnames are ignored as attachment
directives; server-side media fetchers still enforce their own network guards.

Local media attachments can use absolute paths, workspace-relative paths, or
home-relative `~/` paths. They still pass through the agent file-read policy and
media type checks before delivery.

<Warning>
Do not emit text commands for attachments from tools, plugins, streaming blocks,
browser output, or message actions. Use structured media fields instead.

Valid message-tool payload:

```json
{ "message": "Here is your image.", "mediaUrl": "/workspace/image.png" }
```

Legacy final assistant reply text may still be normalized for compatibility, but
it is not a general plugin/tool protocol.
</Warning>

Plain Markdown image syntax stays text by default. Channels that intentionally
map Markdown image replies to media attachments opt in at their outbound
adapter; Telegram does this so `![alt](url)` can still become a media reply.

These directives are separate. Structured media fields and reply/voice tags are
delivery metadata; `[embed ...]` is the web-only rich render path.

When block streaming is enabled, media must be carried on structured payload
fields. If the same media URL is sent in a streamed block and repeated in the
final assistant payload, Mnemo delivers the attachment once and strips the
duplicate from the final payload.

## `[embed ...]`

`[embed ...]` is the only agent-facing rich render syntax for the Control UI.

Self-closing example:

```text
[embed ref="cv_123" title="Status" /]
```

Rules:

- `[view ...]` is no longer valid for new output.
- Embed shortcodes render in the assistant message surface only.
- Only URL-backed embeds are rendered. Use `ref="..."` or `url="..."`.
- Block-form inline HTML embed shortcodes are not rendered.
- The web UI strips the shortcode from visible text and renders the embed inline.
- Structured media is not an embed alias and should not be used for rich embed rendering.

## Stored rendering shape

The normalized/stored assistant content block is a structured `canvas` item:

```json
{
  "type": "canvas",
  "preview": {
    "kind": "canvas",
    "surface": "assistant_message",
    "render": "url",
    "viewId": "cv_123",
    "url": "/__mnemo__/canvas/documents/cv_123/index.html",
    "title": "Status",
    "preferredHeight": 320
  }
}
```

Stored/rendered rich blocks use this `canvas` shape directly. `present_view` is not recognized.

## Related

- [RPC adapters](/reference/rpc)
- [Typebox](/concepts/typebox)
