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

# Media and Files

> Reading R2 media through the brain proxy. Key scoping rules, allowlisted prefixes, streaming vs buffering, and feed media fields.

All binary content (compositions, designs, posters, transcoded video) lives on R2 and is read through the brain's proxy endpoint.

## The one scoping rule

| Source                                                           | Key scope                                               |
| ---------------------------------------------------------------- | ------------------------------------------------------- |
| Portal file index (`portal.listFiles`)                           | workspace-relative                                      |
| Brain agent surfaces (`getItems`, `getFeed`, posters, playables) | agent-scoped (relative to the project's storage prefix) |

The proxy (`brain.streamR2File`) always takes a **workspace-relative** key. When you get a key off a feed post or item, it is agent-scoped; resolve it to the workspace-relative form the same way the platform wrapper does (the project's storage prefix plus the key) before streaming, or route through your own resolution step.

Only allowlisted prefixes are reachable (`projects/`, `workflows/`, `config/`, `assets/`, `meta/`, `wrapper/`, ...). Everything else returns `403`.

## Stream large objects

```ts theme={null}
const res = await client.brain.streamR2File(`projects/${agentId}/output/reel.mp4`);

// pipe to a file
await pipeline(
  Readable.fromWeb(res.body as any),
  createWriteStream('reel.mp4'),
);
```

Never buffer a video or a composition export in memory with `getR2Bytes`; that convenience is for small files like `design-tokens.json`.

## Small text/JSON files

```ts theme={null}
const tokens = JSON.parse(
  await client.brain.getR2Text('config/design-tokens.json'),
);
```

## Feed media fields

A `FeedPost` carries everything you need to render it:

* `poster` — still frame key (always present for video)
* `playable` — mp4/webm key, when a transcode exists
* `isVideo` — quick branch flag
* `pages` — ordered media for carousels and story sets
* `width` / `height` — for layout before the bytes arrive
* `kind` — `still` | `reel` | `carousel` | `story` | `deck` (prefer this over legacy `mediaType`)

## Serving media to browsers

The proxy is authenticated with the workspace key, so browsers cannot hit it directly. Standard patterns:

* Proxy through your backend, forwarding the key server-side.
* Fetch on the server and re-serve from your own storage/CDN.
* Keep the workspace key out of any client bundle. It grants full read of the workspace's published data.