feat: restructure k-launcher workspace and add core functionality

- Updated Cargo.toml to include a new k-launcher crate and reorganized workspace members. - Introduced a README.md file detailing the project philosophy, architecture, and technical specifications. - Implemented a new Kernel struct in k-launcher-kernel for managing plugins and search functionality. - Created a Plugin trait for plugins to implement, allowing for asynchronous search operations. - Developed k-launcher-ui with an Iced-based UI for user interaction, including search input and result display. - Added AppsPlugin and CalcPlugin to handle application launching and basic calculations, respectively. - Established a theme module for UI styling, focusing on an Aero aesthetic. - Removed unnecessary main.rs files from plugin crates, streamlining the project structure.
2026-03-15 16:20:36 +01:00
parent 4c3be17b77
commit 1ac9dde347
19 changed files with 6077 additions and 28 deletions
--- a/Cargo.lock
+++ b/Cargo.lock
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,9 +1,19 @@
 [workspace]
-members = ["crates/k-launcher-kernel", "crates/k-launcher-os-bridge", "crates/k-launcher-ui", "crates/plugins/plugin-apps", "crates/plugins/plugin-calc", "crates/plugins/plugin-files"]
+members = [
+    "crates/k-launcher",
+    "crates/k-launcher-kernel",
+    "crates/k-launcher-os-bridge",
+    "crates/k-launcher-ui",
+    "crates/plugins/plugin-apps",
+    "crates/plugins/plugin-calc",
+    "crates/plugins/plugin-files",
+]
 resolver = "2"

 [workspace.dependencies]
-iced = { version = "0.14", features = ["canvas", "tokio", "wgpu"] }
-tokio = { version = "1.35", features = ["full"] }
+async-trait = "0.1"
+futures = "0.3"
+iced = { version = "0.14", features = ["canvas", "image", "svg", "tokio", "wgpu"] }
 serde = { version = "1.0", features = ["derive"] }
-tracing = "0.1" # For high-performance logging
+tokio = { version = "1.35", features = ["full"] }
+tracing = "0.1"
--- a/README.md
+++ b/README.md
@@ -0,0 +1,56 @@
+# K-Launcher
+
+K-Launcher is a lightweight, GPU-accelerated command palette for Linux (Wayland/X11), macOS, and Windows. It reimagines the "Spotlight" experience through the lens of Frutiger Aero—focusing on gloss, glass, and skeuomorphism—powered by a non-blocking, multi-threaded Rust kernel.
+
+## Core Philosophy
+
+- Zero Webview: No Chromium, no Electron. Every pixel is rendered via WGPU (Iced) for sub-5ms input-to-render latency.
+
+- Async-First: Search queries never block the UI. If the file-searcher is indexing, the calculator still feels instant.
+
+- The "Aero" Standard: Deep support for Gaussian blur (via Layer Shell), linear gradients, and high-gloss textures.
+
+## High-Level Architecture
+
+We are utilizing a "Hub-and-Spoke" model within a Cargo Workspace. The k-launcher-kernel acts as the central hub, dispatching user input to various "Spokes" (Plugins).
+
+### The Crate Hierarchy
+
+| Crate                      | Responsibility                                            | Key Dependencies                       |
+| -------------------------- | --------------------------------------------------------- | -------------------------------------- |
+| **`k-launcher`**           | The entry-point binary. Glues everything together.        | `k-launcher-ui`, `k-launcher-kernel`   |
+| **`k-launcher-ui`**        | The Iced-based view layer. Handles animations/theming.    | `iced`, `lyon` (for vector paths)      |
+| **`k-launcher-kernel`**    | The "Brain." Manages state, history, and plugin dispatch. | `tokio`, `tracing`                     |
+| **`k-launcher-os-bridge`** | OS-specific windowing (Layer Shell for Wayland, Win32).   | `iced_layershell`, `raw-window-handle` |
+| **`plugins/*`**            | Individual features (Calc, Files, Apps, Web).             | `plugin-api` (Shared traits)           |
+
+## Data & Communication Flow
+
+K-Launcher operates on an Event loop.
+
+```
+sequenceDiagram
+    participant User
+    participant UI as k-launcher-ui
+    participant Kernel as k-launcher-kernel
+    participant Plugins as plugin-file-search
+
+    User->>UI: Types "p"
+    UI->>Kernel: QueryUpdate("p")
+    par Parallel Search
+        Kernel->>Plugins: async search("p")
+        Plugins-->>Kernel: List<SearchResult>
+    end
+    Kernel->>UI: NewResults(Vec)
+    UI-->>User: Render Glass Result List
+```
+
+## Technical Specifications
+
+To ensure "Plug and Play" capability, all features must implement the `Plugin` trait. This allows the user to swap the default `file-searcher` for something like `fzf` or `plocate` without recompiling the UI.
+
+To achieve the 2000s aesthetic without a browser:
+
+- Background Blur: On Wayland, we request blur through the org_kde_kwin_blur or fractional-scale protocols.
+- Shaders: We will use Iced’s canvas to draw glossy "shine" overlays that respond to mouse hovering.
+- Icons: We will prefer .svg and .png with high-depth shadows over flat icon fonts.
--- a/crates/k-launcher-kernel/Cargo.toml
+++ b/crates/k-launcher-kernel/Cargo.toml
@@ -4,3 +4,7 @@ version = "0.1.0"
 edition = "2024"

 [dependencies]
+async-trait = { workspace = true }
+futures = { workspace = true }
+serde = { workspace = true }
+tokio = { workspace = true }
--- a/crates/k-launcher-kernel/src/lib.rs
+++ b/crates/k-launcher-kernel/src/lib.rs
@@ -1,14 +1,168 @@
-pub fn add(left: u64, right: u64) -> u64 {
-    left + right
+use std::sync::Arc;
+
+use async_trait::async_trait;
+use futures::future::join_all;
+
+pub type PluginName = &'static str;
+
+// --- Newtypes ---
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash, serde::Serialize, serde::Deserialize)]
+pub struct ResultId(String);
+
+impl ResultId {
+    pub fn new(id: impl Into<String>) -> Self {
+        Self(id.into())
+    }
+    pub fn as_str(&self) -> &str {
+        &self.0
+    }
 }

+#[derive(Debug, Clone, PartialEq, Eq, serde::Serialize, serde::Deserialize)]
+pub struct ResultTitle(String);
+
+impl ResultTitle {
+    pub fn new(title: impl Into<String>) -> Self {
+        Self(title.into())
+    }
+    pub fn as_str(&self) -> &str {
+        &self.0
+    }
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, serde::Serialize, serde::Deserialize)]
+pub struct Score(u32);
+
+impl Score {
+    pub fn new(value: u32) -> Self {
+        Self(value)
+    }
+    pub fn value(self) -> u32 {
+        self.0
+    }
+}
+
+// --- SearchResult ---
+
+pub struct SearchResult {
+    pub id: ResultId,
+    pub title: ResultTitle,
+    pub description: Option<String>,
+    pub icon: Option<String>,
+    pub score: Score,
+    pub on_execute: Arc<dyn Fn() + Send + Sync>,
+}
+
+impl std::fmt::Debug for SearchResult {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("SearchResult")
+            .field("id", &self.id)
+            .field("title", &self.title)
+            .field("icon", &self.icon)
+            .field("score", &self.score)
+            .finish_non_exhaustive()
+    }
+}
+
+// --- Plugin trait ---
+
+#[async_trait]
+pub trait Plugin: Send + Sync {
+    fn name(&self) -> PluginName;
+    async fn search(&self, query: &str) -> Vec<SearchResult>;
+}
+
+// --- Kernel (Application use case) ---
+
+pub struct Kernel {
+    plugins: Vec<Arc<dyn Plugin>>,
+}
+
+impl Kernel {
+    pub fn new(plugins: Vec<Arc<dyn Plugin>>) -> Self {
+        Self { plugins }
+    }
+
+    pub async fn search(&self, query: &str) -> Vec<SearchResult> {
+        let futures = self.plugins.iter().map(|p| p.search(query));
+        let nested: Vec<Vec<SearchResult>> = join_all(futures).await;
+        let mut flat: Vec<SearchResult> = nested.into_iter().flatten().collect();
+        flat.sort_by(|a, b| b.score.cmp(&a.score));
+        flat
+    }
+}
+
+// --- Tests ---
+
 #[cfg(test)]
 mod tests {
    use super::*;

+    struct MockPlugin {
+        results: Vec<(&'static str, u32)>,
+    }
+
+    impl MockPlugin {
+        fn returns(results: Vec<(&'static str, u32)>) -> Self {
+            Self { results }
+        }
+    }
+
+    #[async_trait]
+    impl Plugin for MockPlugin {
+        fn name(&self) -> PluginName {
+            "mock"
+        }
+
+        async fn search(&self, _query: &str) -> Vec<SearchResult> {
+            self.results
+                .iter()
+                .enumerate()
+                .map(|(i, (title, score))| SearchResult {
+                    id: ResultId::new(format!("id-{i}")),
+                    title: ResultTitle::new(*title),
+                    description: None,
+                    icon: None,
+                    score: Score::new(*score),
+                    on_execute: Arc::new(|| {}),
+                })
+                .collect()
+        }
+    }
+
    #[test]
-    fn it_works() {
-        let result = add(2, 2);
-        assert_eq!(result, 4);
+    fn newtype_result_id() {
+        assert_eq!(ResultId::new("x").as_str(), "x");
+    }
+
+    #[test]
+    fn newtype_score() {
+        assert_eq!(Score::new(42).value(), 42);
+    }
+
+    #[test]
+    fn newtype_title() {
+        assert_eq!(ResultTitle::new("hello").as_str(), "hello");
+    }
+
+    #[tokio::test]
+    async fn empty_kernel_returns_empty() {
+        let k = Kernel::new(vec![]);
+        assert!(k.search("x").await.is_empty());
+    }
+
+    #[tokio::test]
+    async fn kernel_sorts_by_score_desc() {
+        let plugin = Arc::new(MockPlugin::returns(vec![
+            ("lower", 5),
+            ("higher", 10),
+            ("middle", 7),
+        ]));
+        let k = Kernel::new(vec![plugin]);
+        let results = k.search("q").await;
+        assert_eq!(results[0].score.value(), 10);
+        assert_eq!(results[1].score.value(), 7);
+        assert_eq!(results[2].score.value(), 5);
    }
 }
--- a/crates/k-launcher-os-bridge/src/lib.rs
+++ b/crates/k-launcher-os-bridge/src/lib.rs
@@ -1,14 +1,20 @@
-pub fn add(left: u64, right: u64) -> u64 {
-    left + right
+/// Configuration for the launcher window.
+pub struct WindowConfig {
+    pub width: f32,
+    pub height: f32,
+    pub decorations: bool,
+    pub transparent: bool,
+    pub resizable: bool,
 }

-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn it_works() {
-        let result = add(2, 2);
-        assert_eq!(result, 4);
+impl WindowConfig {
+    pub fn launcher() -> Self {
+        Self {
+            width: 600.0,
+            height: 400.0,
+            decorations: false,
+            transparent: true,
+            resizable: false,
+        }
    }
 }
--- a/crates/k-launcher-ui/Cargo.toml
+++ b/crates/k-launcher-ui/Cargo.toml
@@ -3,4 +3,11 @@ name = "k-launcher-ui"
 version = "0.1.0"
 edition = "2024"

+[lib]
+name = "k_launcher_ui"
+path = "src/lib.rs"
+
 [dependencies]
+iced = { workspace = true }
+k-launcher-kernel = { path = "../k-launcher-kernel" }
+tokio = { workspace = true }
--- a/crates/k-launcher-ui/src/app.rs
+++ b/crates/k-launcher-ui/src/app.rs
@@ -0,0 +1,179 @@
+use std::sync::Arc;
+
+use iced::{
+    Color, Element, Length, Size, Subscription, Task,
+    keyboard::{self, Event as KeyEvent, Key, key::Named},
+    widget::{column, container, image, row, scrollable, svg, text, text_input, Space},
+    window,
+};
+
+use k_launcher_kernel::{Kernel, SearchResult};
+
+use crate::theme::AeroColors;
+
+static INPUT_ID: std::sync::LazyLock<iced::widget::Id> =
+    std::sync::LazyLock::new(|| iced::widget::Id::new("search"));
+
+pub struct KLauncherApp {
+    kernel: Arc<Kernel>,
+    query: String,
+    results: Arc<Vec<SearchResult>>,
+    selected: usize,
+}
+
+impl KLauncherApp {
+    fn new(kernel: Arc<Kernel>) -> Self {
+        Self {
+            kernel,
+            query: String::new(),
+            results: Arc::new(vec![]),
+            selected: 0,
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub enum Message {
+    QueryChanged(String),
+    ResultsReady(Arc<Vec<SearchResult>>),
+    KeyPressed(KeyEvent),
+}
+
+fn update(state: &mut KLauncherApp, message: Message) -> Task<Message> {
+    match message {
+        Message::QueryChanged(q) => {
+            state.query = q.clone();
+            state.selected = 0;
+            let kernel = state.kernel.clone();
+            Task::perform(
+                async move { kernel.search(&q).await },
+                |results| Message::ResultsReady(Arc::new(results)),
+            )
+        }
+        Message::ResultsReady(results) => {
+            state.results = results;
+            Task::none()
+        }
+        Message::KeyPressed(event) => {
+            let key = match event {
+                KeyEvent::KeyPressed { key, .. } => key,
+                _ => return Task::none(),
+            };
+            let Key::Named(named) = key else {
+                return Task::none();
+            };
+            let len = state.results.len();
+            match named {
+                Named::Escape => std::process::exit(0),
+                Named::ArrowDown => {
+                    if len > 0 {
+                        state.selected = (state.selected + 1).min(len - 1);
+                    }
+                }
+                Named::ArrowUp => {
+                    if state.selected > 0 {
+                        state.selected -= 1;
+                    }
+                }
+                Named::Enter => {
+                    if let Some(result) = state.results.get(state.selected) {
+                        (result.on_execute)();
+                    }
+                    std::process::exit(0);
+                }
+                _ => {}
+            }
+            Task::none()
+        }
+    }
+}
+
+fn view(state: &KLauncherApp) -> Element<'_, Message> {
+    let colors = AeroColors::standard();
+
+    let search_bar = text_input("Search...", &state.query)
+        .id(INPUT_ID.clone())
+        .on_input(Message::QueryChanged)
+        .padding(12)
+        .size(18);
+
+    let result_rows: Vec<Element<'_, Message>> = state
+        .results
+        .iter()
+        .enumerate()
+        .map(|(i, result)| {
+            let is_selected = i == state.selected;
+            let bg_color = if is_selected {
+                colors.border_cyan
+            } else {
+                Color::from_rgba8(255, 255, 255, 0.07)
+            };
+            let icon_el: Element<'_, Message> = match &result.icon {
+                Some(p) if p.ends_with(".svg") =>
+                    svg(svg::Handle::from_path(p)).width(24).height(24).into(),
+                Some(p) =>
+                    image(image::Handle::from_path(p)).width(24).height(24).into(),
+                None => Space::new().width(24).height(24).into(),
+            };
+            container(
+                row![icon_el, text(result.title.as_str()).size(15)]
+                    .spacing(8)
+                    .align_y(iced::Center),
+            )
+                .width(Length::Fill)
+                .padding([6, 12])
+                .style(move |_theme| container::Style {
+                    background: Some(iced::Background::Color(bg_color)),
+                    ..Default::default()
+                })
+                .into()
+        })
+        .collect();
+
+    let results_list =
+        scrollable(column(result_rows).spacing(2).width(Length::Fill)).height(Length::Fill);
+
+    let content = column![search_bar, results_list]
+        .spacing(8)
+        .padding(12)
+        .width(Length::Fill)
+        .height(Length::Fill);
+
+    container(content)
+        .width(Length::Fill)
+        .height(Length::Fill)
+        .style(|_theme| container::Style {
+            background: Some(iced::Background::Color(Color::from_rgba8(
+                20, 20, 30, 0.9,
+            ))),
+            ..Default::default()
+        })
+        .into()
+}
+
+fn subscription(_state: &KLauncherApp) -> Subscription<Message> {
+    keyboard::listen().map(Message::KeyPressed)
+}
+
+pub fn run(kernel: Arc<Kernel>) -> iced::Result {
+    iced::application(
+        move || {
+            let app = KLauncherApp::new(kernel.clone());
+            let focus = iced::widget::operation::focus(INPUT_ID.clone());
+            (app, focus)
+        },
+        update,
+        view,
+    )
+        .title("K-Launcher")
+        .subscription(subscription)
+        .window(window::Settings {
+            size: Size::new(600.0, 400.0),
+            position: window::Position::Centered,
+            decorations: false,
+            transparent: true,
+            resizable: false,
+            ..Default::default()
+        })
+        .run()
+}
--- a/crates/k-launcher-ui/src/lib.rs
+++ b/crates/k-launcher-ui/src/lib.rs
@@ -0,0 +1,11 @@
+mod app;
+pub mod theme;
+
+use std::sync::Arc;
+
+use k_launcher_kernel::Kernel;
+
+
+pub fn run(kernel: Arc<Kernel>) -> iced::Result {
+    app::run(kernel)
+}
--- a/crates/k-launcher-ui/src/main.rs
+++ b/crates/k-launcher-ui/src/main.rs
@@ -1,3 +0,0 @@
-fn main() {
-    println!("Hello, world!");
-}
--- a/crates/k-launcher-ui/src/theme.rs
+++ b/crates/k-launcher-ui/src/theme.rs
@@ -0,0 +1,32 @@
+use iced::{
+    Color, Gradient,
+    gradient::{ColorStop, Linear},
+};
+
+pub struct AeroColors {
+    pub glass_bg: Color,
+    pub gloss_highlight: Gradient,
+    pub border_cyan: Color,
+}
+
+impl AeroColors {
+    pub fn standard() -> Self {
+        Self {
+            // Semi-transparent "Aero Glass" base
+            glass_bg: Color::from_rgba8(255, 255, 255, 0.2),
+            // Cyan/Blue glow typical of the 2008 era
+            border_cyan: Color::from_rgb8(0, 183, 235),
+            // We'll use this for the "shine" effect on buttons
+            gloss_highlight: Gradient::Linear(Linear::new(0.0).add_stops([
+                ColorStop {
+                    color: Color::from_rgba8(255, 255, 255, 0.5),
+                    offset: 0.0,
+                },
+                ColorStop {
+                    color: Color::from_rgba8(255, 255, 255, 0.0),
+                    offset: 1.0,
+                },
+            ])),
+        }
+    }
+}
--- a/crates/k-launcher/Cargo.toml
+++ b/crates/k-launcher/Cargo.toml
@@ -0,0 +1,17 @@
+[package]
+name = "k-launcher"
+version = "0.1.0"
+edition = "2024"
+default-run = "k-launcher"
+
+[[bin]]
+name = "k-launcher"
+path = "src/main.rs"
+
+[dependencies]
+iced = { workspace = true }
+k-launcher-kernel = { path = "../k-launcher-kernel" }
+k-launcher-ui = { path = "../k-launcher-ui" }
+plugin-apps = { path = "../plugins/plugin-apps" }
+plugin-calc = { path = "../plugins/plugin-calc" }
+tokio = { workspace = true }
--- a/crates/k-launcher/src/main.rs
+++ b/crates/k-launcher/src/main.rs
@@ -0,0 +1,13 @@
+use std::sync::Arc;
+
+use k_launcher_kernel::Kernel;
+use plugin_apps::{AppsPlugin, FsDesktopEntrySource};
+use plugin_calc::CalcPlugin;
+
+fn main() -> iced::Result {
+    let kernel = Arc::new(Kernel::new(vec![
+        Arc::new(CalcPlugin::new()),
+        Arc::new(AppsPlugin::new(FsDesktopEntrySource::new())),
+    ]));
+    k_launcher_ui::run(kernel)
+}
--- a/crates/plugins/plugin-apps/Cargo.toml
+++ b/crates/plugins/plugin-apps/Cargo.toml
@@ -3,4 +3,17 @@ name = "plugin-apps"
 version = "0.1.0"
 edition = "2024"

+[lib]
+name = "plugin_apps"
+path = "src/lib.rs"
+
+[[bin]]
+name = "plugin-apps"
+path = "src/main.rs"
+
 [dependencies]
+async-trait = { workspace = true }
+k-launcher-kernel = { path = "../../k-launcher-kernel" }
+libc = "0.2"
+tokio = { workspace = true }
+xdg = "2"
--- a/crates/plugins/plugin-apps/src/lib.rs
+++ b/crates/plugins/plugin-apps/src/lib.rs
@@ -0,0 +1,291 @@
+use std::{path::Path, process::{Command, Stdio}, sync::Arc};
+use std::os::unix::process::CommandExt;
+
+use async_trait::async_trait;
+use k_launcher_kernel::{Plugin, PluginName, ResultId, ResultTitle, Score, SearchResult};
+
+// --- Domain newtypes ---
+
+#[derive(Debug, Clone)]
+pub struct AppName(String);
+
+impl AppName {
+    pub fn new(s: impl Into<String>) -> Self {
+        Self(s.into())
+    }
+    pub fn as_str(&self) -> &str {
+        &self.0
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct ExecCommand(String);
+
+impl ExecCommand {
+    pub fn new(s: impl Into<String>) -> Self {
+        Self(s.into())
+    }
+    pub fn as_str(&self) -> &str {
+        &self.0
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct IconPath(String);
+
+impl IconPath {
+    pub fn new(s: impl Into<String>) -> Self {
+        Self(s.into())
+    }
+    pub fn as_str(&self) -> &str {
+        &self.0
+    }
+}
+
+// --- Desktop entry ---
+
+pub struct DesktopEntry {
+    pub name: AppName,
+    pub exec: ExecCommand,
+    pub icon: Option<IconPath>,
+}
+
+// --- Swappable source trait (Application layer principle) ---
+
+pub trait DesktopEntrySource: Send + Sync {
+    fn entries(&self) -> Vec<DesktopEntry>;
+}
+
+// --- Plugin ---
+
+pub struct AppsPlugin<S: DesktopEntrySource> {
+    source: S,
+}
+
+impl<S: DesktopEntrySource> AppsPlugin<S> {
+    pub fn new(source: S) -> Self {
+        Self { source }
+    }
+}
+
+fn resolve_icon_path(name: &str) -> Option<String> {
+    if name.starts_with('/') && Path::new(name).exists() {
+        return Some(name.to_string());
+    }
+    let candidates = [
+        format!("/usr/share/pixmaps/{name}.png"),
+        format!("/usr/share/pixmaps/{name}.svg"),
+        format!("/usr/share/icons/hicolor/48x48/apps/{name}.png"),
+        format!("/usr/share/icons/hicolor/scalable/apps/{name}.svg"),
+    ];
+    candidates.into_iter().find(|p| Path::new(p).exists())
+}
+
+fn score_match(name: &str, query: &str) -> Option<u32> {
+    let name_lc = name.to_lowercase();
+    let query_lc = query.to_lowercase();
+    if name_lc == query_lc {
+        Some(100)
+    } else if name_lc.starts_with(&query_lc) {
+        Some(80)
+    } else if name_lc.contains(&query_lc) {
+        Some(60)
+    } else {
+        None
+    }
+}
+
+#[async_trait]
+impl<S: DesktopEntrySource> Plugin for AppsPlugin<S> {
+    fn name(&self) -> PluginName {
+        "apps"
+    }
+
+    async fn search(&self, query: &str) -> Vec<SearchResult> {
+        if query.is_empty() {
+            return vec![];
+        }
+        self.source
+            .entries()
+            .into_iter()
+            .filter_map(|entry| {
+                score_match(entry.name.as_str(), query).map(|score| {
+                    let exec = entry.exec.clone();
+                    let icon = entry.icon.as_ref().and_then(|p| resolve_icon_path(p.as_str()));
+                    SearchResult {
+                        id: ResultId::new(format!("app-{}", entry.name.as_str())),
+                        title: ResultTitle::new(entry.name.as_str()),
+                        description: None,
+                        icon,
+                        score: Score::new(score),
+                        on_execute: Arc::new(move || {
+                            let parts: Vec<&str> = exec.as_str().split_whitespace().collect();
+                            if let Some((cmd, args)) = parts.split_first() {
+                                let _ = unsafe {
+                                    Command::new(cmd)
+                                        .args(args)
+                                        .stdin(Stdio::null())
+                                        .stdout(Stdio::null())
+                                        .stderr(Stdio::null())
+                                        .pre_exec(|| { libc::setsid(); Ok(()) })
+                                        .spawn()
+                                };
+                            }
+                        }),
+                    }
+                })
+            })
+            .collect()
+    }
+}
+
+// --- Filesystem source ---
+
+pub struct FsDesktopEntrySource;
+
+impl FsDesktopEntrySource {
+    pub fn new() -> Self {
+        Self
+    }
+}
+
+impl Default for FsDesktopEntrySource {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl DesktopEntrySource for FsDesktopEntrySource {
+    fn entries(&self) -> Vec<DesktopEntry> {
+        let mut dirs = Vec::new();
+        if let Ok(xdg) = xdg::BaseDirectories::new() {
+            dirs.push(xdg.get_data_home().join("applications"));
+            for d in xdg.get_data_dirs() {
+                dirs.push(d.join("applications"));
+            }
+        }
+        let mut entries = Vec::new();
+        for dir in &dirs {
+            if let Ok(read_dir) = std::fs::read_dir(dir) {
+                for entry in read_dir.flatten() {
+                    let path = entry.path();
+                    if path.extension().and_then(|e| e.to_str()) != Some("desktop") {
+                        continue;
+                    }
+                    if let Some(de) = parse_desktop_file(&path) {
+                        entries.push(de);
+                    }
+                }
+            }
+        }
+        entries
+    }
+}
+
+fn parse_desktop_file(path: &Path) -> Option<DesktopEntry> {
+    let content = std::fs::read_to_string(path).ok()?;
+    let mut in_section = false;
+    let mut name: Option<String> = None;
+    let mut exec: Option<String> = None;
+    let mut icon: Option<String> = None;
+    let mut entry_type: Option<String> = None;
+    let mut no_display = false;
+
+    for line in content.lines() {
+        let line = line.trim();
+        if line == "[Desktop Entry]" {
+            in_section = true;
+            continue;
+        }
+        if line.starts_with('[') {
+            in_section = false;
+            continue;
+        }
+        if !in_section || line.starts_with('#') || line.is_empty() {
+            continue;
+        }
+        if let Some((key, value)) = line.split_once('=') {
+            match key.trim() {
+                "Name" if name.is_none() => name = Some(value.trim().to_string()),
+                "Exec" if exec.is_none() => exec = Some(value.trim().to_string()),
+                "Icon" if icon.is_none() => icon = Some(value.trim().to_string()),
+                "Type" if entry_type.is_none() => entry_type = Some(value.trim().to_string()),
+                "NoDisplay" => no_display = value.trim().eq_ignore_ascii_case("true"),
+                _ => {}
+            }
+        }
+    }
+
+    if entry_type.as_deref() != Some("Application") || no_display {
+        return None;
+    }
+
+    let exec_clean: String = exec?
+        .split_whitespace()
+        .filter(|s| !s.starts_with('%'))
+        .collect::<Vec<_>>()
+        .join(" ");
+
+    Some(DesktopEntry {
+        name: AppName::new(name?),
+        exec: ExecCommand::new(exec_clean),
+        icon: icon.map(IconPath::new),
+    })
+}
+
+// --- Tests ---
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    struct MockSource {
+        entries: Vec<(String, String)>, // (name, exec)
+    }
+
+    impl MockSource {
+        fn with(entries: Vec<(&str, &str)>) -> Self {
+            Self {
+                entries: entries
+                    .into_iter()
+                    .map(|(n, e)| (n.to_string(), e.to_string()))
+                    .collect(),
+            }
+        }
+    }
+
+    impl DesktopEntrySource for MockSource {
+        fn entries(&self) -> Vec<DesktopEntry> {
+            self.entries
+                .iter()
+                .map(|(name, exec)| DesktopEntry {
+                    name: AppName::new(name.clone()),
+                    exec: ExecCommand::new(exec.clone()),
+                    icon: None,
+                })
+                .collect()
+        }
+    }
+
+    #[tokio::test]
+    async fn apps_prefix_match() {
+        let source = MockSource::with(vec![("Firefox", "firefox")]);
+        let p = AppsPlugin::new(source);
+        let results = p.search("fire").await;
+        assert_eq!(results[0].title.as_str(), "Firefox");
+    }
+
+    #[tokio::test]
+    async fn apps_no_match_returns_empty() {
+        let source = MockSource::with(vec![("Firefox", "firefox")]);
+        let p = AppsPlugin::new(source);
+        assert!(p.search("zz").await.is_empty());
+    }
+
+    #[tokio::test]
+    async fn apps_empty_query_returns_empty() {
+        let source = MockSource::with(vec![("Firefox", "firefox")]);
+        let p = AppsPlugin::new(source);
+        assert!(p.search("").await.is_empty());
+    }
+}
--- a/crates/plugins/plugin-apps/src/main.rs
+++ b/crates/plugins/plugin-apps/src/main.rs
@@ -1,3 +1 @@
-fn main() {
-    println!("Hello, world!");
-}
+fn main() {}
--- a/crates/plugins/plugin-calc/Cargo.toml
+++ b/crates/plugins/plugin-calc/Cargo.toml
@@ -3,4 +3,16 @@ name = "plugin-calc"
 version = "0.1.0"
 edition = "2024"

+[lib]
+name = "plugin_calc"
+path = "src/lib.rs"
+
+[[bin]]
+name = "plugin-calc"
+path = "src/main.rs"
+
 [dependencies]
+async-trait = { workspace = true }
+evalexpr = "11"
+k-launcher-kernel = { path = "../../k-launcher-kernel" }
+tokio = { workspace = true }
--- a/crates/plugins/plugin-calc/src/lib.rs
+++ b/crates/plugins/plugin-calc/src/lib.rs
@@ -0,0 +1,83 @@
+use std::sync::Arc;
+
+use async_trait::async_trait;
+use k_launcher_kernel::{Plugin, PluginName, ResultId, ResultTitle, Score, SearchResult};
+
+pub struct CalcPlugin;
+
+impl CalcPlugin {
+    pub fn new() -> Self {
+        Self
+    }
+}
+
+impl Default for CalcPlugin {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+fn should_eval(query: &str) -> bool {
+    query
+        .chars()
+        .next()
+        .map(|c| c.is_ascii_digit() || c == '(' || c == '-')
+        .unwrap_or(false)
+        || query.starts_with('=')
+}
+
+#[async_trait]
+impl Plugin for CalcPlugin {
+    fn name(&self) -> PluginName {
+        "calc"
+    }
+
+    async fn search(&self, query: &str) -> Vec<SearchResult> {
+        if !should_eval(query) {
+            return vec![];
+        }
+        let expr = query.strip_prefix('=').unwrap_or(query);
+        match evalexpr::eval_number(expr) {
+            Ok(n) if n.is_finite() => {
+                let display = if n.fract() == 0.0 {
+                    format!("= {}", n as i64)
+                } else {
+                    format!("= {n}")
+                };
+                vec![SearchResult {
+                    id: ResultId::new("calc-result"),
+                    title: ResultTitle::new(display),
+                    description: None,
+                    icon: None,
+                    score: Score::new(90),
+                    on_execute: Arc::new(|| {}),
+                }]
+            }
+            _ => vec![],
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[tokio::test]
+    async fn calc_valid_expr() {
+        let p = CalcPlugin::new();
+        let results = p.search("2+2").await;
+        assert_eq!(results[0].title.as_str(), "= 4");
+    }
+
+    #[tokio::test]
+    async fn calc_non_numeric_returns_empty() {
+        let p = CalcPlugin::new();
+        assert!(p.search("firefox").await.is_empty());
+    }
+
+    #[tokio::test]
+    async fn calc_bad_expr_returns_empty() {
+        let p = CalcPlugin::new();
+        assert!(p.search("1/0").await.is_empty());
+    }
+}
--- a/crates/plugins/plugin-calc/src/main.rs
+++ b/crates/plugins/plugin-calc/src/main.rs
@@ -1,3 +1 @@
-fn main() {
-    println!("Hello, world!");
-}
+fn main() {}