The Salesforce host passes its locale to your embedded app, so the app can render its interface in the Salesforce user's language.
Where: This change applies to Lightning Experience, Experience Cloud LWR and Aura sites, and the Salesforce mobile app in Enterprise, Performance, Unlimited, Developer, and Partner Developer editions hosted on Hyperforce where English is the default language.
When: This feature is available starting September 14, 2026.
Who: This change is for developers who build embedded apps and who can create Lightning web components.
Why: Give users a consistent experience by showing the embedded app in the same language as the rest of Salesforce.
How: Salesforce dispatches the host locale to the embedded app through a custom event. Your app reads the locale and renders its own interface in that language. Localizing your app's content and labels remains your app's responsibility.