Bennet Fenner

Bennet Fenner is a software engineer at Zed and a maintainer of the Agent Client Protocol’s Rust and TypeScript SDKs. He builds open-source infrastructure that connects coding agents to editors while keeping their work visible to developers.

Fenner began programming professionally in 2019, building Windows desktop applications in C#, and returned to university in 2022 to study computer science at TU Darmstadt. That year, he originated and prototyped the QuestPDF Previewer, a hot-reloading document preview tool that lets developers inspect changes without repeatedly recompiling.

After discovering Zed in 2023, Fenner started contributing when its Rust-based editor became open source in January 2024. He worked on scrollbar diagnostics, interface improvements, and collaboration features, pairing with Zed engineers before joining as an intern. In April 2024, he became Zed’s first hire from its open-source contributor community. His subsequent work ranged from indentation guides and preview tabs to coding-agent infrastructure; he now maintains both official Agent Client Protocol SDKs. Zed documents his path from contributor to teammate.

Building agents that belong inside editors

• Open editor-agent interoperability. The Agent Client Protocol provides a shared JSON-RPC interface, allowing editors to support different coding agents without building a custom integration for each pairing.

• Stateful agent sessions. Fenner’s live coding-agent implementation turns stateless model requests into persistent conversations: the application retains history, executes requested tools, returns their results, and manages initialization, capabilities, cancellation, and standard-I/O connections.

• Visible, editor-aware tool execution. Streaming updates expose generated text and tool progress, structured edits become readable diffs, and editor-mediated file access includes unsaved editor buffers. Client-managed terminals likewise surface commands and results inside the development environment.