---

## CitationChip
Compact source marker rendered for a `[id]` citation. StreamingMarkdown wires it up automatically from its `sources` prop — each in-text marker becomes a CitationChip whose click opens a Popover with the source title, snippet, and a policy-checked outbound link. Also usable standalone for source footers / reference lists outside a streamed message.

**Import:** `import { CitationChip } from '@urbicon-ui/blocks';`

### Variants
- citationStyle: label, numeric (default: numeric)

### Api
| Prop | Type | Required | Default | Description |
| --- | --- | :---: | --- | --- |
| source | `CitationSource` | yes |  | The cited source. Required. |
| ...HTMLButtonAttributes | `HTMLAttributes` | no |  | HTML attributes (excluding: 'class' | 'children') |
| citationStyle | `'numeric' | 'label'` | no | 'numeric' | What the chip shows: `numeric` renders `index` (or `source.id` as a fallback) as a compact numeric pill; `label` renders the (truncated) `source.title`. |
| class | `string` | no |  | Extra classes merged onto the trigger chip (the root slot). |
| index | `number` | no |  | 1-based ordinal shown as the chip label under `citationStyle="numeric"`. Falls back to `source.id` when omitted. |
| label | `string` | no |  | Override the trigger's `aria-label`. Defaults to `Source {index}: {title}` (or `Source: {title}` without an index). |
| openLabel | `string` | no | 'Open source' | Text of the outbound link in the popover. |
| preset | `string` | no |  | Apply a named preset registered via `<BlocksProvider presets={{ CitationChip: {...} }}>`. Prefer this over `class` overrides when the requested look falls outside the semantic intent palette. |
| slotClasses | `Partial<Record<CitationChipSlots, string>>` | no |  | Per-slot class overrides. Slots: `trigger` (root chip), `popover` (content wrapper), `title`, `snippet`, `link`, `linkIcon`. |
| unstyled | `boolean` | no |  | Strip all default tv() classes; combine with `class` / `slotClasses` for a custom look. |
| urlPolicy | `MarkdownUrlPolicy` | no |  | URL policy applied to `source.url` before it becomes a link (same strict default as the streaming-markdown engine — untrusted LLM output). A blocked URL yields no link in the popover, only title/snippet. |

Inherited from:
- Omit<HTMLButtonAttributes, 'class' | 'children'> (omit-pattern)

### Types
```ts
interface CitationSource {
/** Stable id — matches the `[id]` marker in the streamed markdown. */
  id: string;
  /** Human-readable source title, always shown in the popover (and as the chip label under `citationStyle="label"`). */
  title: string;
  /** Source URL. Rendered as an outbound link only when it passes the `urlPolicy`; a blocked or absent URL shows title/snippet with no link. */
  url?: string;
  /** Short excerpt shown under the title, clamped to ~3 lines. */
  snippet?: string;
}
```

```ts
interface MarkdownUrlPolicy {
/**
   * Allowed link protocols (with trailing colon). Relative URLs are always
   * allowed for links. @default ['http:', 'https:', 'mailto:', 'tel:']
   */
  allowedLinkProtocols?: string[];
  /**
   * Prefix allowlist for image sources, matched against the normalized
   * absolute URL. Empty (the default) blocks every external image; relative
   * sources are allowed. Prefer deep, specific prefixes — broad ones are
   * open-redirect bait. `data:` images are blocked unless a `data:` prefix
   * is listed explicitly.
   * @default []
   */
  allowedImagePrefixes?: string[];
  /** Observability hook — fires once per blocked URL occurrence. */
  onBlocked?: (kind: 'link' | 'image', url: string) => void;
}
```

```ts
type SlotNames = keyof ReturnType<T> & string
```

### Slots (slotClasses keys)
`trigger`, `popover`, `title`, `snippet`, `link`, `linkIcon`