AI SDK 6

AI SDK 6 introduces a new `Agent` abstraction for building reusable agents, including `ToolLoopAgent` for production-ready tool execution loops and `callOptionsSchema` for type-safe arguments. It enhances code organization and UI integration with end-to-end type safety. Custom agent implementations are supported via the `Agent` interface, enabling durable and resumable workflows with `DurableAgent`. Tool improvements include `needsApproval` for human-in-the-loop control, strict mode for reliable input generation, input examples for better alignment, and `toModelOutput` for flexible tool outputs. New features also include DevTools for debugging agent interactions, reranking, standard JSON schema support, image editing capabilities, raw finish reason & extended usage reporting, a LangChain adapter rewrite, and new provider tools.