UserInputContent

type UserInputContent = UserContent;

User-turn content the runtime accepts: plain text, or AI SDK multimodal parts (text + file/image/audio). This is exactly the content of a user ModelMessage, so it threads into the model with no translation.

Durability invariant: any FilePart.data flowing through the runtime must be JSON-serializable (a base64 string, data URL, or https URL) — never a raw Buffer/Uint8Array. RunState.messages, session.messages, and the pending input buffer are all persisted through the SessionStore (JSON/Redis/Postgres).