bezel

A gpui component library, SwiftUI-lean: style flows through the environment, never through parameters, and its numbers are measured rather than chosen — the type ladder is NSFont.preferredFont(forTextStyle:), the gap between siblings is NSStackView().spacing. CONTRIBUTING.md has the laws.

https://github.com/user-attachments/assets/34861f29-004f-47f0-89e6-42cc8772749f

use bezel::ui::widgets::{ButtonStyle, Buttons};
theme.button("Save", ButtonStyle::Prominent, None)

Install

[dependencies]
bezel = "0.1"

An app also names the two crates the facade cannot cover — gpui because actions! expands to literal gpui:: paths, and gpui_platform because the facade re-exports gpui but not the platform. Both are our fork of gpui, published under bezel-gpui*; the package key keeps the gpui:: paths the macros and gpui's own docs expect:

gpui = { package = "bezel-gpui", version = "0.3" }
gpui_platform = { package = "bezel-gpui-platform", version = "0.3", features = ["font-kit"] }

Theme

Most apps want the shipped palette in their own hues. That is a Brand — one hue for the greys, one for the accent, one base radius:

use bezel::theme::{self, Brand, Tint};

// before appearance::init
theme::set_brand(
    Brand {
        tint: Tint::new(257.417, 0.046),
        accent: Tint::new(276.935, 0.182),
        radius: 8.0,
    },
    cx,
);

Lightness is not a knob, so a branded palette keeps the contrast ratios the shipped one was verified at. The gallery's Theme page is this struct with sliders on it, and prints the call back.

For colors a hue rotation cannot reach, register a palette builder instead — it runs first, and a brand rotates whatever it returns:

use bezel::theme::{Theme, set_palette};

theme::set_palette(|appearance| {
    let mut theme = Theme::for_appearance(appearance);
    theme.danger = my_red(appearance);
    theme
}, cx);

Build an app

apps/hello is the smallest consumer — one window, a button, a toggle. Every gpui type path goes through bezel::gpui, so a second gpui cannot creep into the graph. The bootstrap, which is the part no snippet can skip:

use bezel::gpui::{App, AppContext as _, Bounds, WindowBounds, WindowOptions, px, size};
use bezel::theme::{self, Theme};
use bezel::ui;

fn main() {
    gpui_platform::application()
        .run(|cx: &mut App| {
            if let Err(err) = ui::register_fonts(cx) {
                eprintln!("FONT REGISTRATION FAILED: {err:?}");
            }
            theme::appearance::init(theme::appearance::AppearanceMode::System, cx);
            let bounds = Bounds::centered(None, size(px(520.0), px(360.0)), cx);
            cx.open_window(
                WindowOptions {
                    window_bounds: Some(WindowBounds::Windowed(bounds)),
                    ..Default::default()
                },
                |window, cx| {
                    theme::appearance::observe_window(window, cx).detach();
                    cx.new(Hello::new)
                },
            )
            .unwrap();
            cx.activate(true);
        });
}

Hello is a struct implementing Render; its render reads the theme with Theme::of(cx) and builds elements through the widgets traits. Run cargo run -p hello and read apps/hello/src/main.rs for the rest.

Agents

Every doc page is served as markdown — append .md to any docs URL, or take the whole corpus from llms.txt and llms-full.txt.

skills/ holds two agent skills, plain SKILL.md files any agent that reads the format can load. skills/bezel teaches an agent to use the library — the bootstrap, the laws, and the traps that only bite at runtime. skills/bezel-contributing is for working on it.

Provenance