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

# Cover Media

> Treat cover images and media as verifiable first-class Capsule and evidence references.

# Cover media

Visual media is part of how journalism is identified, shared and understood. PressChain therefore treats cover media as more than a decorative URL.

The canonical Capsule metadata envelope includes both `cover_media_uri` and optional `cover_media_hash`. Canonical read models also expose a `cover_url`, and the V3 evidence record includes `coverUrl` and `metadataURI` fields for evidence presentation.

## Store a durable reference

A cover URI should resolve to the media artifact or to a durable content address. Avoid using a temporary image optimization URL that contains a short-lived signature as the canonical reference.

Your delivery stack can still create transformed thumbnails. Keep the original canonical reference and hash available for verification.

## Hash the original bytes

If `cover_media_hash` is present, hash the exact canonical media bytes before upload or immediately after retrieving the stored object.

```ts theme={null}
async function sha256Hex(bytes: ArrayBuffer) {
  const digest = await crypto.subtle.digest("SHA-256", bytes);
  return "0x" + [...new Uint8Array(digest)]
    .map((b) => b.toString(16).padStart(2, "0"))
    .join("");
}
```

Use the hash algorithm required by the canonical metadata implementation for the specific field. The snippet above demonstrates browser byte hashing and should not replace a protocol-defined algorithm when one is specified.

## Rich Capsule cards

A good Capsule card can show:

* cover image
* title
* author and outlet
* publication timestamp
* canonical source
* content and metadata verification state
* evidence count
* revision count

The cover should not be cropped so aggressively that important journalistic context disappears. Preserve aspect ratio metadata in the application layer when available.

## Evidence media

Evidence has its own `coverUrl`. This is useful for a PDF preview, photograph, scan, chart or other visual artifact associated with the evidence item.

Keep the distinction between the evidence `uri`, which points at the evidence artifact, and `coverUrl`, which is a presentation reference. A screenshot preview is not a substitute for the underlying source document.

## Handling unavailable media

A missing image should not make the Capsule unreadable. Fall back to title, identity and verification data while preserving the original URI and hash in an inspection view.

Useful states include:

* media verified
* media available but unverified
* media hash mismatch
* media unavailable
* no cover declared

This is more accurate than silently swapping in an unrelated stock image.

## Why first-class media matters

Explorer and Portal surfaces can use the same canonical cover reference to render recognizable records. Third-party applications can do the same without scraping an article page for Open Graph metadata.

That produces a better developer contract: the publication record itself says which media belongs to it and, when a hash is provided, how to verify that media.