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# `TrustedHosts`

Built-in mappings of dialog hosts (e.g. `tempo.xyz`) to the third-party origins they trust to embed them, plus helpers to test a hostname against a trusted-host list.

The `dialog` adapter consults these mappings to decide whether the calling page is allowed to embed the dialog. Patterns starting with `*.` match any subdomain suffix (e.g. `*.workers.dev` matches `foo.workers.dev`).

## Usage

```ts twoslash
import { TrustedHosts } from 'accounts'

const trusted = TrustedHosts.hosts['tempo.xyz']!

const ok = TrustedHosts.match(trusted, 'app.tempo.xyz')
```

## Properties

### hosts

* **Type:** `Record<string, readonly string[]>`

Trusted host mappings. Each key is a dialog host, and its value is the list of third-party origins that the dialog trusts to embed it. Supports wildcard patterns (e.g. `*.workers.dev`).

```ts twoslash
import { TrustedHosts } from 'accounts'

const trusted = TrustedHosts.hosts['tempo.xyz'] // [!code focus]
```

## Functions

### match

* **Type:** `(trustedHosts: readonly string[], hostname: string, source?: string) => boolean`

Returns `true` if `hostname` matches any pattern in `trustedHosts`, or (when `source` is provided) if `hostname` shares the same registrable domain ("eTLD+1") as `source`.

Patterns starting with `*.` match any subdomain suffix (e.g. `*.workers.dev` matches `foo.workers.dev`).

```ts twoslash
import { TrustedHosts } from 'accounts'

const trusted = TrustedHosts.hosts['tempo.xyz']!

const ok = TrustedHosts.match(trusted, 'app.tempo.xyz') // [!code focus]
```

### sameRegistrableDomain

* **Type:** `(a: string, b: string) => boolean`

Returns `true` if `a` and `b` share the same registrable domain ("eTLD+1").

```ts twoslash
import { TrustedHosts } from 'accounts'

const ok = TrustedHosts.sameRegistrableDomain( // [!code focus]
  'app.tempo.xyz', // [!code focus]
  'docs.tempo.xyz', // [!code focus]
) // [!code focus]
```