A company uses Dynamics 365 live chat on its website.

The Live Chat SDK is the principal client-side extension surface for programmatically controlling the web chat experience. Microsoft exposes methods and events for starting or closing chats, supplying custom context, working with authentication providers, reacting to widget lifecycle events, and implementing customized customer-facing behavior. Microsoft also provides the Omnichannel Chat SDK and UI components for organizations that require deeper control of a bespoke chat interface.

The Omnichannel JavaScript API provides another programmable extension surface for Contact Center conversation operations. It includes APIs for retrieving and opening conversations, linking records, retrieving conversation identifiers, and programmatically sending messages. This makes it applicable when customized behavior must bridge the web experience and Dynamics 365 conversation functionality.

Context variables are primarily conversation attributes used for routing decisions and productivity tools; they are not a general-purpose mechanism for altering the website chat application's behavior. Standard widget settings can change supported presentation options, but the question explicitly requires extending behavior beyond default capability. SDK/API extensibility therefore provides the required level of customization.

Study Guide reference: Implement channels - > Configure and embed a chat widget; extend the chat experience using the live chat SDK.