Lucent

A D-Bus activated Wayland notification daemon in Rust with zero resident idle footprint.

Architecture & Philosophy

Lucent implements org.freedesktop.Notifications as a D-Bus-activated service (org.freedesktop.Notifications.service) rather than a permanently running daemon.

• Headless activation path: no systemd --user unit and no compositor autostart stanza are required.
• Zero idle residency: when no notification is sent, Lucent is not running and consumes no resident memory.
• Event-driven runtime: process startup is triggered by D-Bus method calls; notification lifecycle is driven by IPC events.
• Rust memory safety: notification state, IPC routing, and rendering are implemented in Rust, with Wayland surfaces via gtk4-layer-shell.

Compared to legacy X11-era notification daemons (long-lived background services with startup orchestration), Lucent is bus-activated and compositor-native on Wayland.

Warning

Lucent requires a Wayland session and layer-shell support through the GTK4/layer-shell stack.

Installation

Arch Linux (AUR)

lucent

paru -S lucent

All packages install:

• lucent to /usr/bin/lucent
• D-Bus activation file to /usr/share/dbus-1/services/org.freedesktop.Notifications.service

Building from Source (Non-Arch)

git clone https://github.com/CPT-Dawn/Lucent.git
cd Lucent
cargo build --release --locked

Install binary and D-Bus service file:

sudo install -Dm755 target/release/lucent /usr/bin/lucent
sudo install -Dm644 org.freedesktop.Notifications.service \
  /usr/share/dbus-1/services/org.freedesktop.Notifications.service

Warning

If org.freedesktop.Notifications.service is not installed in a D-Bus service directory, D-Bus activation will not occur.

Configuration

Configuration is loaded from XDG config location:

• Primary path: ~/.config/lucent/config.toml
• Source of defaults: embedded default_config.toml written automatically on first run

Reference configuration:

# Lucent configuration
# Location: ~/.config/lucent/config.toml

# Width of each notification popup in pixels.
width = 350

# Default auto-dismiss timeout in seconds.
timeout_seconds = 5

# Window background color (hex, optional alpha).
background_color = "#0D0B14E6"

# Border color (hex).
border_color = "#1A1525"

# Border width in px (0 disables border).
border_width = 1

# Text color (hex).
text_color = "#E8E2F0"

# Corner radius in pixels.
corner_radius = 12

# Font family used for title/body text.
font_family = "Geist"

# Max visible notifications before queueing.
max_visible_notifications = 5

Blur And Borderless Popups (Hyprland + Wayland)

Lucent renders translucent GTK layer-shell windows. The actual blur effect is provided by your Wayland compositor, not by Lucent itself.

1) Tune Lucent for blur-friendly visuals

Set these values in ~/.config/lucent/config.toml:

# Keep alpha in background color (last 2 hex digits), e.g. E6 = 90% opacity.
background_color = "#0D0B14E6"

# Remove sharp outline for a cleaner blurred card look.
border_width = 0

If your popup looks too opaque, reduce alpha (for example CC instead of E6).

2) Hyprland configuration

In your Hyprland config (~/.config/hypr/hyprland.conf), ensure blur is enabled and apply layer rules to Lucent's namespace (lucent-notification):

decoration {
  blur {
    enabled = true
    size = 8
    passes = 3
    ignore_opacity = false
  }
}

layerrule = blur, lucent-notification
layerrule = ignorealpha 0.15, lucent-notification

Then reload Hyprland:

hyprctl reload

3) Other Wayland compositors

Use your compositor's blur and layer-surface/window rules targeting the lucent-notification namespace/app class equivalent. Keep Lucent background translucent and set border_width = 0 if you want a fully soft-edge style.

Usage & IPC

Standard freedesktop clients work without Lucent-specific integration:

notify-send "Build completed" "All targets passed"

Raw D-Bus IPC example:

dbus-send --session --type=method_call --print-reply \
  --dest=org.freedesktop.Notifications \
  /org/freedesktop/Notifications \
  org.freedesktop.Notifications.Notify \
  string:"manual-test" uint32:0 string:"" string:"Summary" string:"Body" \
  array:string:"" dict:string:variant:"" int32:5000

CLI surface:

• lucent currently exposes no custom command-line flags.
• Lifecycle is managed by D-Bus activation, not by daemon control subcommands.

Contributing

Pull requests are welcome, but review is strict on correctness and maintainability.

Before opening a PR, ensure all of the following are true:

cargo fmt --all
cargo clippy --all-targets --all-features -- -D warnings

PR requirements:

• Code is fully formatted with cargo fmt.
• cargo clippy passes with zero warnings.
• Description includes a clear architectural explanation of what changed and why.

License

MIT. See LICENSE.