Ark is an R kernel for Jupyter applications. It was created to serve as the interface between R and the Positron IDE and is compatible with all frontends implementing the Jupyter protocol. Ark aims to provide a complete set of reusable and interoperable tools for implementing IDEs for R: - It is a Jupyter kernel that provides structured interaction (inputs and outputs) between R and a frontend. - It is an LSP server that powers intellisense features such as completions, jump-to-definition, find-references, diagnostics, etc. It also has some formatting capabilities that we plan to develop over time. - It is a DAP server for sophisticated step-debugging of R functions. It manages source references, creating them on the spot if needed, and integrates tightly with the Jupyter kernel to step through R code transparently and inspect local variables. Note: Support for breakpoints is currently missing but you can use debug(), debugonce(), or browser() to drop into the debugger. The LSP and DAP features are currently only available in Positron but will be made available to other frontends in the future.