eye-declare #

A library for building inline 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.

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.