Juggler

Juggler is a GUI first AI coding harness built by Julian Storer, the developer behind JUCE, Tracktion and Cmajor. It is a desktop interface and matching server for working with coding agents over long sessions, with every model transaction open to inspection. The backend is a native Go server, and the interface is type checked JavaScript served directly with no frontend compilation step and no Electron. Conversations are stored as Yjs documents, so local and remote clients stay in sync live. The agent turn cycle runs as a state machine of named transitions rather than a loop, so an approval is a state instead of a blocked process and a turn can be interrupted and resumed later. Threads branch like a tree: a tangent, a delegated task or a competing approach can go into a sub thread, and only its result returns to the main context. Tool calls, item properties, history and context are laid out in a Miller column view. Everything in Juggler is an extension, including the built in read, write and bash tools, so there is no privileged inner tier. Extensions can supply tools, strategies, slash commands, workspace providers such as git worktrees, file viewers, sidebar cards and pinned views, and a scaffold command starts a new one. Juggler is open source and free, needs no account, is vendor neutral, and connects directly to the user's own model provider.