Optional_The _meta property is reserved by ACP to allow clients and agents to attach additional metadata to their interactions. Implementations MUST NOT make assumptions about values at these keys.
See protocol docs: Extensibility
The language identifier of the document (e.g., "rust", "python").
The session ID for this notification.
The full text content of the document.
The URI of the opened document.
The version number of the document.
Notification sent when a file is opened in the editor.