Support native Tern surfaces through TSP

Would an optional Tern Surface Protocol frontend be a suitable integration for fx?

Tern Surface Protocol lets a terminal application describe semantic transcript cards, tool progress, approvals, and an editor. Tern owns layout and native interaction. The application retains state and execution authority. Official SDKs include TypeScript, Go, Python, and Rust.

A bounded approach could use an optional frontend over the existing fx acp interface. fx would remain responsible for model requests, tools, permissions, sessions, credentials, and persistence. The normal Zig terminal UI and other ACP clients would remain unchanged. A Tern plugin alone cannot replace the rendering and input state of an existing terminal application.

Initial acceptance should cover exact Unicode edit/send, explicit allow/reject permissions, resize, cancellation, clean exit with shell restoration, and detach/reattach. Ordinary terminals must retain a usable fallback.

I found no existing Tern/TSP issue in open or closed issues. Discussions are currently disabled. This proposal asks about the integration boundary before any upstream implementation PR.