eye-declare #

A library for building inline-first terminal UIs in Rust: interfaces that live in your terminal's normal flow, where finished output scrolls into native scrollback and only a small live region updates in place.

eye-declare is built for CLI tools, AI agents, and interactive prompts: the programs where output accumulates and history should stay visible, exactly as if the program had printed it. When an app needs the whole terminal instead, the same model runs fullscreen on the alternate screen.

Rust Docs #

For the rustdoc documentation, visit https://docs.rs/eye_declare.

Example #

The whole design in one small fragment: a streaming agent turn. Content lives in the live tail while it's changing; the moment it's finished, ctx.push commits it to scrollback, like println!:

struct Agent {
    response: String,
    streaming: Option<Task>,
}

enum Msg {
    Delta(String),
    Done,
}

impl App for Agent {
    type Msg = Msg;
    type Output = ();

    fn update(&mut self, msg: Msg, ctx: &mut Ctx<'_, Self>) {
        match msg {
            // Still changing: lives in the tail.
            Msg::Delta(word) => self.response.push_str(&word),
            // Finished: commit to scrollback.
            Msg::Done => {
                let reply = std::mem::take(&mut self.response);
                ctx.push(markdown(reply));
                self.streaming = None;
            }
        }
    }

    // The live region: a pure view of the model, rebuilt every frame.
    fn tail(&self) -> impl Element + '_ {
        col()
            .when(self.streaming.is_some(), |c| {
                c.child(spinner("Thinking…"))
            })
            .child(text(self.response.as_str()))
    }
}

Messages arrive from terminal input through a keymap and from async work through ctx.spawn — both shown in the quick start, which builds a complete runnable app in about sixty lines.

Examples #

The repository ships runnable examples that double as learning material:

• echo — the smallest useful app: type, Enter commits, Ctrl+C exits.
• stream — a mini agent: a streaming turn with a spinner, Esc cancels.
• openrouter — a real streaming AI chat TUI in one commented file.

Where to go next #

Start with the introduction for the idea behind the design, or jump to the quick start to build a working app. The guide covers the concepts in depth; the reference documents the widgets, runtime, and migration path.