style: format code for better readability in tests and function signatures

P1 bugs:
- unix_launcher: shell_split respects quoted args (was split_whitespace)
- plugin-host: 5s timeout on external plugin search
- ui: handle engine init panic, wire error state
- ui-egui: read window config instead of always using defaults
- plugin-url: use OpenPath action instead of SpawnProcess+xdg-open

Architecture:
- remove WindowConfig (mirror of WindowCfg); use WindowCfg directly
- remove on_select closure from SearchResult (domain leakage)
- remove LaunchAction::Custom; add Plugin::on_selected + SearchEngine::on_selected
- apps: record frecency via on_selected instead of embedded closure

Design smells:
- frecency: extract decay_factor helper, write outside mutex
- apps: remove cfg(test) cache_path hack; add new_for_test ctor
- apps: stable ResultId using name+exec to prevent collision
- files: stable ResultId using full path instead of index
- plugin-host: remove k-launcher-os-bridge dep (WindowConfig gone)

Cargo.toml

@@ -13,13 +13,27 @@ members = [
     "crates/k-launcher-ui-egui",
     "crates/plugins/plugin-url",
 ]
+default-members = [
+    "crates/k-launcher",
+    "crates/k-launcher-config",
+    "crates/k-launcher-kernel",
+    "crates/k-launcher-os-bridge",
+    "crates/k-launcher-plugin-host",
+    "crates/k-launcher-ui",
+    "crates/plugins/plugin-apps",
+    "crates/plugins/plugin-calc",
+    "crates/plugins/plugin-cmd",
+    "crates/plugins/plugin-files",
+    "crates/plugins/plugin-url",
+]
 resolver = "2"
 
 [workspace.dependencies]
 async-trait = "0.1"
+bincode = { version = "2", features = ["serde"] }
 dirs = "6.0"
 futures = "0.3"
-iced = { version = "0.14", features = ["image", "svg", "tokio", "tiny-skia"] }
+iced = { version = "0.14", default-features = false, features = ["image", "svg", "tokio", "tiny-skia", "wayland", "x11", "crisp", "web-colors", "thread-pool"] }
 serde = { version = "1.0", features = ["derive"] }
 serde_json = "1"
 tokio = { version = "1.35", features = ["rt-multi-thread", "macros"] }

crates/k-launcher-kernel/Cargo.toml

@@ -8,3 +8,4 @@ async-trait = { workspace = true }
 futures = { workspace = true }
 serde = { workspace = true }
 tokio = { workspace = true }
+tracing = { workspace = true }

crates/k-launcher-kernel/src/lib.rs

@@ -50,7 +50,6 @@ pub enum LaunchAction {
     SpawnInTerminal(String),
     OpenPath(String),
     CopyToClipboard(String),
-    Custom(Arc<dyn Fn() + Send + Sync>),
 }
 
 // --- AppLauncher port trait ---
@@ -68,7 +67,6 @@ pub struct SearchResult {
     pub icon: Option<String>,
     pub score: Score,
     pub action: LaunchAction,
-    pub on_select: Option<Arc<dyn Fn() + Send + Sync>>,
 }
 
 impl std::fmt::Debug for SearchResult {
@@ -88,6 +86,7 @@ impl std::fmt::Debug for SearchResult {
 pub trait Plugin: Send + Sync {
     fn name(&self) -> &str;
     async fn search(&self, query: &str) -> Vec<SearchResult>;
+    fn on_selected(&self, _id: &ResultId) {}
 }
 
 // --- SearchEngine port trait ---
@@ -95,6 +94,19 @@ pub trait Plugin: Send + Sync {
 #[async_trait]
 pub trait SearchEngine: Send + Sync {
     async fn search(&self, query: &str) -> Vec<SearchResult>;
+    fn on_selected(&self, id: &ResultId);
+}
+
+// --- NullSearchEngine ---
+
+pub struct NullSearchEngine;
+
+#[async_trait]
+impl SearchEngine for NullSearchEngine {
+    async fn search(&self, _query: &str) -> Vec<SearchResult> {
+        vec![]
+    }
+    fn on_selected(&self, _id: &ResultId) {}
 }
 
 // --- Kernel (Application use case) ---
@@ -112,10 +124,32 @@ impl Kernel {
         }
     }
 
+    pub fn on_selected(&self, id: &ResultId) {
+        for plugin in &self.plugins {
+            plugin.on_selected(id);
+        }
+    }
+
     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();
+        use futures::FutureExt;
+        use std::panic::AssertUnwindSafe;
+
+        let futures = self
+            .plugins
+            .iter()
+            .map(|p| AssertUnwindSafe(p.search(query)).catch_unwind());
+        let outcomes = join_all(futures).await;
+        let mut flat: Vec<SearchResult> = outcomes
+            .into_iter()
+            .zip(self.plugins.iter())
+            .flat_map(|(outcome, plugin)| match outcome {
+                Ok(results) => results,
+                Err(_) => {
+                    tracing::error!(plugin = plugin.name(), "plugin panicked during search");
+                    vec![]
+                }
+            })
+            .collect();
         flat.sort_by(|a, b| b.score.cmp(&a.score));
         flat.truncate(self.max_results);
         flat
@@ -127,6 +161,9 @@ impl SearchEngine for Kernel {
     async fn search(&self, query: &str) -> Vec<SearchResult> {
         self.search(query).await
     }
+    fn on_selected(&self, id: &ResultId) {
+        self.on_selected(id);
+    }
 }
 
 // --- Tests ---
@@ -161,8 +198,7 @@ mod tests {
                     description: None,
                     icon: None,
                     score: Score::new(*score),
-                    action: LaunchAction::Custom(Arc::new(|| {})),
-                    on_select: None,
+                    action: LaunchAction::SpawnProcess("mock".to_string()),
                 })
                 .collect()
         }
@@ -203,6 +239,29 @@ mod tests {
         assert_eq!(results[2].score.value(), 5);
     }
 
+    struct PanicPlugin;
+
+    #[async_trait]
+    impl Plugin for PanicPlugin {
+        fn name(&self) -> &str {
+            "panic-plugin"
+        }
+
+        async fn search(&self, _query: &str) -> Vec<SearchResult> {
+            panic!("test panic");
+        }
+    }
+
+    #[tokio::test]
+    async fn kernel_continues_after_plugin_panic() {
+        let panic_plugin = Arc::new(PanicPlugin);
+        let normal_plugin = Arc::new(MockPlugin::returns(vec![("survivor", 5)]));
+        let k = Kernel::new(vec![panic_plugin, normal_plugin], 8);
+        let results = k.search("q").await;
+        assert_eq!(results.len(), 1);
+        assert_eq!(results[0].title.as_str(), "survivor");
+    }
+
     #[tokio::test]
     async fn kernel_truncates_at_max_results() {
         let plugin = Arc::new(MockPlugin::returns(vec![

crates/k-launcher-os-bridge/Cargo.toml

@@ -4,6 +4,5 @@ version = "0.1.0"
 edition = "2024"
 
 [dependencies]
-k-launcher-config = { path = "../k-launcher-config" }
 k-launcher-kernel = { path = "../k-launcher-kernel" }
 libc = "0.2"

crates/k-launcher-os-bridge/src/lib.rs

@@ -1,23 +1,2 @@
 mod unix_launcher;
-
 pub use unix_launcher::UnixAppLauncher;
-
-pub struct WindowConfig {
-    pub width: f32,
-    pub height: f32,
-    pub decorations: bool,
-    pub transparent: bool,
-    pub resizable: bool,
-}
-
-impl WindowConfig {
-    pub fn from_cfg(w: &k_launcher_config::WindowCfg) -> Self {
-        Self {
-            width: w.width,
-            height: w.height,
-            decorations: w.decorations,
-            transparent: w.transparent,
-            resizable: w.resizable,
-        }
-    }
-}

crates/k-launcher-os-bridge/src/unix_launcher.rs

@@ -3,6 +3,29 @@ use std::process::{Command, Stdio};
 
 use k_launcher_kernel::{AppLauncher, LaunchAction};
 
+fn shell_split(cmd: &str) -> Vec<String> {
+    let mut tokens = Vec::new();
+    let mut current = String::new();
+    let mut in_quotes = false;
+
+    for ch in cmd.chars() {
+        match ch {
+            '"' => in_quotes = !in_quotes,
+            ' ' | '\t' if !in_quotes => {
+                if !current.is_empty() {
+                    tokens.push(current.clone());
+                    current.clear();
+                }
+            }
+            _ => current.push(ch),
+        }
+    }
+    if !current.is_empty() {
+        tokens.push(current);
+    }
+    tokens
+}
+
 fn parse_term_cmd(s: &str) -> (String, Vec<String>) {
     let mut parts = s.split_whitespace();
     let bin = parts.next().unwrap_or("").to_string();
@@ -69,7 +92,7 @@ impl AppLauncher for UnixAppLauncher {
     fn execute(&self, action: &LaunchAction) {
         match action {
             LaunchAction::SpawnProcess(cmd) => {
-                let parts: Vec<&str> = cmd.split_whitespace().collect();
+                let parts = shell_split(cmd);
                 if let Some((bin, args)) = parts.split_first() {
                     let _ = unsafe {
                         Command::new(bin)
@@ -121,7 +144,47 @@ impl AppLauncher for UnixAppLauncher {
                     }
                 }
             }
-            LaunchAction::Custom(f) => f(),
         }
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::shell_split;
+
+    #[test]
+    fn split_simple() {
+        assert_eq!(shell_split("firefox"), vec!["firefox"]);
+    }
+
+    #[test]
+    fn split_with_args() {
+        assert_eq!(
+            shell_split("firefox --new-window"),
+            vec!["firefox", "--new-window"]
+        );
+    }
+
+    #[test]
+    fn split_quoted_path() {
+        assert_eq!(shell_split(r#""My App" --flag"#), vec!["My App", "--flag"]);
+    }
+
+    #[test]
+    fn split_quoted_with_spaces() {
+        assert_eq!(
+            shell_split(r#"env "FOO BAR" baz"#),
+            vec!["env", "FOO BAR", "baz"]
+        );
+    }
+
+    #[test]
+    fn split_empty() {
+        assert!(shell_split("").is_empty());
+    }
+
+    #[test]
+    fn split_extra_whitespace() {
+        assert_eq!(shell_split("  a   b  "), vec!["a", "b"]);
+    }
+}

crates/k-launcher-plugin-host/Cargo.toml

@@ -12,5 +12,5 @@ async-trait = { workspace = true }
 k-launcher-kernel = { path = "../k-launcher-kernel" }
 serde = { workspace = true }
 serde_json = { workspace = true }
-tokio = { workspace = true, features = ["process", "io-util", "sync"] }
+tokio = { workspace = true, features = ["process", "io-util", "sync", "time"] }
 tracing = { workspace = true }

crates/k-launcher-plugin-host/src/lib.rs

@@ -105,7 +105,14 @@ impl Plugin for ExternalPlugin {
         }
 
         let result = match guard.as_mut() {
-            Some(io) => do_search(io, query).await,
+            Some(io) => {
+                tokio::time::timeout(std::time::Duration::from_secs(5), do_search(io, query))
+                    .await
+                    .unwrap_or_else(|_| {
+                        tracing::warn!("plugin {} search timed out", self.name);
+                        Err("timeout".into())
+                    })
+            }
             None => unreachable!(),
         };
 
@@ -125,7 +132,6 @@ impl Plugin for ExternalPlugin {
                         }
                         ExternalAction::OpenPath { path } => LaunchAction::OpenPath(path),
                     },
-                    on_select: None,
                 })
                 .collect(),
             Err(e) => {

crates/k-launcher-ui-egui/Cargo.toml

@@ -12,5 +12,4 @@ eframe = { version = "0.31", default-features = false, features = ["default_font
 egui = "0.31"
 k-launcher-config = { path = "../k-launcher-config" }
 k-launcher-kernel = { path = "../k-launcher-kernel" }
-k-launcher-os-bridge = { path = "../k-launcher-os-bridge" }
 tokio = { workspace = true }

crates/k-launcher-ui-egui/src/app.rs

@@ -2,7 +2,6 @@ use std::sync::{Arc, mpsc};
 
 use egui::{Color32, Key, ViewportCommand};
 use k_launcher_kernel::{AppLauncher, SearchEngine, SearchResult};
-use k_launcher_os_bridge::WindowConfig;
 
 const BG: Color32 = Color32::from_rgba_premultiplied(20, 20, 30, 230);
 const BORDER_COLOR: Color32 = Color32::from_rgb(229, 125, 33);
@@ -83,9 +82,7 @@ impl eframe::App for KLauncherApp {
 
         if launch_selected {
             if let Some(result) = self.results.get(self.selected) {
-                if let Some(on_select) = &result.on_select {
-                    on_select();
-                }
+                self.engine.on_selected(&result.id);
                 self.launcher.execute(&result.action);
             }
             ctx.send_viewport_cmd(ViewportCommand::Close);
@@ -166,17 +163,17 @@ impl eframe::App for KLauncherApp {
 pub fn run(
     engine: Arc<dyn SearchEngine>,
     launcher: Arc<dyn AppLauncher>,
+    window_cfg: &k_launcher_config::WindowCfg,
 ) -> Result<(), eframe::Error> {
-    let wc = WindowConfig::from_cfg(&k_launcher_config::WindowCfg::default());
     let rt = tokio::runtime::Runtime::new().expect("tokio runtime");
     let handle = rt.handle().clone();
 
     let options = eframe::NativeOptions {
         viewport: egui::ViewportBuilder::default()
-            .with_inner_size([wc.width, wc.height])
-            .with_decorations(wc.decorations)
-            .with_transparent(wc.transparent)
-            .with_resizable(wc.resizable)
+            .with_inner_size([window_cfg.width, window_cfg.height])
+            .with_decorations(window_cfg.decorations)
+            .with_transparent(window_cfg.transparent)
+            .with_resizable(window_cfg.resizable)
             .with_always_on_top(),
         ..Default::default()
     };

crates/k-launcher-ui-egui/src/lib.rs

@@ -7,6 +7,7 @@ use k_launcher_kernel::{AppLauncher, SearchEngine};
 pub fn run(
     engine: Arc<dyn SearchEngine>,
     launcher: Arc<dyn AppLauncher>,
+    window_cfg: &k_launcher_config::WindowCfg,
 ) -> Result<(), eframe::Error> {
-    app::run(engine, launcher)
+    app::run(engine, launcher, window_cfg)
 }

crates/k-launcher-ui/src/app.rs

@@ -8,12 +8,20 @@ use iced::{
 };
 
 use k_launcher_config::AppearanceCfg;
-use k_launcher_kernel::{AppLauncher, SearchEngine, SearchResult};
-use k_launcher_os_bridge::WindowConfig;
+use k_launcher_kernel::{AppLauncher, NullSearchEngine, SearchEngine, SearchResult};
 
 static INPUT_ID: std::sync::LazyLock<iced::widget::Id> =
     std::sync::LazyLock::new(|| iced::widget::Id::new("search"));
 
+#[derive(Clone)]
+pub(crate) struct EngineHandle(Arc<dyn SearchEngine>);
+
+impl std::fmt::Debug for EngineHandle {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.write_str("EngineHandle")
+    }
+}
+
 fn rgba(c: &[f32; 4]) -> Color {
     Color::from_rgba8(c[0] as u8, c[1] as u8, c[2] as u8, c[3])
 }
@@ -53,6 +61,8 @@ pub enum Message {
     QueryChanged(String),
     ResultsReady(u64, Arc<Vec<SearchResult>>),
     KeyPressed(KeyEvent),
+    EngineReady(EngineHandle),
+    EngineInitFailed(String),
 }
 
 fn update(state: &mut KLauncherApp, message: Message) -> Task<Message> {
@@ -78,6 +88,18 @@ fn update(state: &mut KLauncherApp, message: Message) -> Task<Message> {
             }
             Task::none()
         }
+        Message::EngineInitFailed(msg) => {
+            state.error = Some(msg);
+            Task::none()
+        }
+        Message::EngineReady(handle) => {
+            state.engine = handle.0;
+            if !state.query.is_empty() {
+                let q = state.query.clone();
+                return Task::done(Message::QueryChanged(q));
+            }
+            Task::none()
+        }
         Message::KeyPressed(event) => {
             let key = match event {
                 KeyEvent::KeyPressed { key, .. } => key,
@@ -103,9 +125,7 @@ fn update(state: &mut KLauncherApp, message: Message) -> Task<Message> {
                 }
                 Named::Enter => {
                     if let Some(result) = state.results.get(state.selected) {
-                        if let Some(on_select) = &result.on_select {
-                            on_select();
-                        }
+                        state.engine.on_selected(&result.id);
                         state.launcher.execute(&result.action);
                     }
                     std::process::exit(0);
@@ -254,17 +274,32 @@ fn subscription(_state: &KLauncherApp) -> Subscription<Message> {
 }
 
 pub fn run(
-    engine: Arc<dyn SearchEngine>,
+    engine_factory: Arc<dyn Fn() -> Arc<dyn SearchEngine> + Send + Sync>,
     launcher: Arc<dyn AppLauncher>,
     window_cfg: &k_launcher_config::WindowCfg,
     appearance_cfg: AppearanceCfg,
 ) -> iced::Result {
-    let wc = WindowConfig::from_cfg(window_cfg);
     iced::application(
         move || {
-            let app = KLauncherApp::new(engine.clone(), launcher.clone(), appearance_cfg.clone());
+            let app = KLauncherApp::new(
+                Arc::new(NullSearchEngine),
+                launcher.clone(),
+                appearance_cfg.clone(),
+            );
             let focus = iced::widget::operation::focus(INPUT_ID.clone());
-            (app, focus)
+            let ef = engine_factory.clone();
+            let init = Task::perform(
+                async move {
+                    tokio::task::spawn_blocking(move || ef())
+                        .await
+                        .map_err(|e| format!("Engine init failed: {e}"))
+                },
+                |result| match result {
+                    Ok(e) => Message::EngineReady(EngineHandle(e)),
+                    Err(msg) => Message::EngineInitFailed(msg),
+                },
+            );
+            (app, Task::batch([focus, init]))
         },
         update,
         view,
@@ -272,11 +307,11 @@ pub fn run(
     .title("K-Launcher")
     .subscription(subscription)
     .window(window::Settings {
-        size: Size::new(wc.width, wc.height),
+        size: Size::new(window_cfg.width, window_cfg.height),
         position: window::Position::Centered,
-        decorations: wc.decorations,
-        transparent: wc.transparent,
-        resizable: wc.resizable,
+        decorations: window_cfg.decorations,
+        transparent: window_cfg.transparent,
+        resizable: window_cfg.resizable,
         ..Default::default()
     })
     .run()

crates/k-launcher-ui/src/lib.rs

@@ -6,10 +6,10 @@ use k_launcher_config::{AppearanceCfg, WindowCfg};
 use k_launcher_kernel::{AppLauncher, SearchEngine};
 
 pub fn run(
-    engine: Arc<dyn SearchEngine>,
+    engine_factory: Arc<dyn Fn() -> Arc<dyn SearchEngine> + Send + Sync>,
     launcher: Arc<dyn AppLauncher>,
     window_cfg: &WindowCfg,
     appearance_cfg: AppearanceCfg,
 ) -> iced::Result {
-    app::run(engine, launcher, window_cfg, appearance_cfg)
+    app::run(engine_factory, launcher, window_cfg, appearance_cfg)
 }

crates/k-launcher/Cargo.toml

@@ -34,5 +34,8 @@ plugin-apps = { path = "../plugins/plugin-apps" }
 plugin-calc = { path = "../plugins/plugin-calc" }
 plugin-cmd = { path = "../plugins/plugin-cmd" }
 plugin-files = { path = "../plugins/plugin-files" }
+dirs = { workspace = true }
 tokio = { workspace = true }
+tracing = { workspace = true }
+tracing-appender = "0.2"
 tracing-subscriber = { version = "0.3", features = ["env-filter"] }

crates/k-launcher/src/main.rs

@@ -10,8 +10,30 @@ use plugin_calc::CalcPlugin;
 use plugin_cmd::CmdPlugin;
 use plugin_files::FilesPlugin;
 
+fn init_logging() -> tracing_appender::non_blocking::WorkerGuard {
+    use tracing_subscriber::{EnvFilter, layer::SubscriberExt, util::SubscriberInitExt};
+
+    let log_dir = dirs::data_local_dir()
+        .map(|d| d.join("k-launcher/logs"))
+        .unwrap_or_else(|| std::path::PathBuf::from("/tmp/k-launcher/logs"));
+    std::fs::create_dir_all(&log_dir).ok();
+
+    let file_appender = tracing_appender::rolling::daily(&log_dir, "k-launcher.log");
+    let (non_blocking, guard) = tracing_appender::non_blocking(file_appender);
+
+    let env_filter = EnvFilter::try_from_default_env().unwrap_or_else(|_| EnvFilter::new("info"));
+
+    tracing_subscriber::registry()
+        .with(env_filter)
+        .with(tracing_subscriber::fmt::layer().with_writer(std::io::stderr))
+        .with(tracing_subscriber::fmt::layer().with_writer(non_blocking))
+        .init();
+
+    guard
+}
+
 fn main() {
-    tracing_subscriber::fmt::init();
+    let _guard = init_logging();
 
     if let Err(e) = run_ui() {
         eprintln!("error: UI: {e}");
@@ -19,11 +41,8 @@ fn main() {
     }
 }
 
-fn run_ui() -> iced::Result {
-    let cfg = k_launcher_config::load();
-    let launcher = Arc::new(UnixAppLauncher::new());
+fn build_engine(cfg: Arc<k_launcher_config::Config>) -> Arc<dyn k_launcher_kernel::SearchEngine> {
     let frecency = FrecencyStore::load();
-
     let mut plugins: Vec<Arc<dyn k_launcher_kernel::Plugin>> = vec![];
     if cfg.plugins.cmd {
         plugins.push(Arc::new(CmdPlugin::new()));
@@ -47,9 +66,14 @@ fn run_ui() -> iced::Result {
             ext.args.clone(),
         )));
     }
-
-    let kernel: Arc<dyn k_launcher_kernel::SearchEngine> =
-        Arc::new(Kernel::new(plugins, cfg.search.max_results));
-
-    k_launcher_ui::run(kernel, launcher, &cfg.window, cfg.appearance)
+    Arc::new(Kernel::new(plugins, cfg.search.max_results))
+}
+
+fn run_ui() -> iced::Result {
+    let cfg = Arc::new(k_launcher_config::load());
+    let launcher = Arc::new(UnixAppLauncher::new());
+    let factory_cfg = cfg.clone();
+    let factory: Arc<dyn Fn() -> Arc<dyn k_launcher_kernel::SearchEngine> + Send + Sync> =
+        Arc::new(move || build_engine(factory_cfg.clone()));
+    k_launcher_ui::run(factory, launcher, &cfg.window, cfg.appearance.clone())
 }

crates/k-launcher/src/main_egui.rs

@@ -10,6 +10,7 @@ use plugin_cmd::CmdPlugin;
 use plugin_files::FilesPlugin;
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let cfg = k_launcher_config::load();
     let launcher = Arc::new(UnixAppLauncher::new());
     let frecency = FrecencyStore::load();
     let kernel: Arc<dyn k_launcher_kernel::SearchEngine> = Arc::new(Kernel::new(
@@ -21,6 +22,6 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
         ],
         8,
     ));
-    k_launcher_ui_egui::run(kernel, launcher)?;
+    k_launcher_ui_egui::run(kernel, launcher, &cfg.window)?;
     Ok(())
 }

crates/plugins/plugin-apps/Cargo.toml

@@ -9,6 +9,8 @@ path = "src/lib.rs"
 
 [dependencies]
 async-trait = { workspace = true }
+bincode = { workspace = true }
+dirs = { workspace = true }
 k-launcher-kernel = { path = "../../k-launcher-kernel" }
 nucleo-matcher = "0.3"
 serde = { workspace = true }

crates/plugins/plugin-apps/src/frecency.rs

@@ -55,17 +55,20 @@ impl FrecencyStore {
             .duration_since(UNIX_EPOCH)
             .unwrap_or_default()
             .as_secs();
-        let mut data = self.data.lock().unwrap();
-        let entry = data.entry(id.to_string()).or_insert(Entry {
-            count: 0,
-            last_used: 0,
-        });
-        entry.count += 1;
-        entry.last_used = now;
-        if let Some(parent) = self.path.parent() {
-            let _ = std::fs::create_dir_all(parent);
-        }
-        if let Ok(json) = serde_json::to_string(&*data) {
+        let json = {
+            let mut data = self.data.lock().unwrap();
+            let entry = data.entry(id.to_string()).or_insert(Entry {
+                count: 0,
+                last_used: 0,
+            });
+            entry.count += 1;
+            entry.last_used = now;
+            serde_json::to_string(&*data).ok()
+        }; // lock released here
+        if let Some(json) = json {
+            if let Some(parent) = self.path.parent() {
+                let _ = std::fs::create_dir_all(parent);
+            }
             let _ = std::fs::write(&self.path, json);
         }
     }
@@ -78,14 +81,7 @@ impl FrecencyStore {
             .unwrap_or_default()
             .as_secs();
         let age_secs = now.saturating_sub(entry.last_used);
-        let decay = if age_secs < 3600 {
-            4
-        } else if age_secs < 86400 {
-            2
-        } else {
-            1
-        };
-        entry.count * decay
+        entry.count * decay_factor(age_secs)
     }
 
     pub fn top_ids(&self, n: usize) -> Vec<String> {
@@ -98,14 +94,7 @@ impl FrecencyStore {
             .iter()
             .map(|(id, entry)| {
                 let age_secs = now.saturating_sub(entry.last_used);
-                let decay = if age_secs < 3600 {
-                    4
-                } else if age_secs < 86400 {
-                    2
-                } else {
-                    1
-                };
-                (id.clone(), entry.count * decay)
+                (id.clone(), entry.count * decay_factor(age_secs))
             })
             .collect();
         scored.sort_by(|a, b| b.1.cmp(&a.1));
@@ -113,6 +102,16 @@ impl FrecencyStore {
     }
 }
 
+fn decay_factor(age_secs: u64) -> u32 {
+    if age_secs < 3600 {
+        4
+    } else if age_secs < 86400 {
+        2
+    } else {
+        1
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;

crates/plugins/plugin-apps/src/lib.rs

@@ -2,7 +2,11 @@ pub mod frecency;
 #[cfg(target_os = "linux")]
 pub mod linux;
 
-use std::{collections::HashMap, sync::Arc};
+use std::{
+    collections::HashMap,
+    path::{Path, PathBuf},
+    sync::{Arc, RwLock},
+};
 
 use async_trait::async_trait;
 use k_launcher_kernel::{LaunchAction, Plugin, ResultId, ResultTitle, Score, SearchResult};
@@ -72,51 +76,148 @@ struct CachedEntry {
     category: Option<String>,
     icon: Option<String>,
     exec: String,
-    on_select: Arc<dyn Fn() + Send + Sync>,
+}
+
+// --- Serializable cache data (no closures) ---
+
+#[derive(serde::Serialize, serde::Deserialize)]
+struct CachedEntryData {
+    id: String,
+    name: String,
+    keywords_lc: Vec<String>,
+    category: Option<String>,
+    icon: Option<String>,
+    exec: String,
+}
+
+fn cache_path() -> Option<PathBuf> {
+    dirs::cache_dir().map(|d| d.join("k-launcher/apps.bin"))
+}
+
+fn load_from_path(path: &Path) -> Option<HashMap<String, CachedEntry>> {
+    let data = std::fs::read(path).ok()?;
+    let (entries_data, _): (Vec<CachedEntryData>, _) =
+        bincode::serde::decode_from_slice(&data, bincode::config::standard()).ok()?;
+    let map = entries_data
+        .into_iter()
+        .map(|e| {
+            let cached = CachedEntry {
+                id: e.id.clone(),
+                name: AppName::new(e.name),
+                keywords_lc: e.keywords_lc,
+                category: e.category,
+                icon: e.icon,
+                exec: e.exec,
+            };
+            (e.id, cached)
+        })
+        .collect();
+    Some(map)
+}
+
+fn save_to_path(path: &Path, entries: &HashMap<String, CachedEntry>) {
+    if let Some(dir) = path.parent() {
+        std::fs::create_dir_all(dir).ok();
+    }
+    let data: Vec<CachedEntryData> = entries
+        .values()
+        .map(|e| CachedEntryData {
+            id: e.id.clone(),
+            name: e.name.as_str().to_string(),
+            keywords_lc: e.keywords_lc.clone(),
+            category: e.category.clone(),
+            icon: e.icon.clone(),
+            exec: e.exec.clone(),
+        })
+        .collect();
+    if let Ok(encoded) = bincode::serde::encode_to_vec(&data, bincode::config::standard()) {
+        std::fs::write(path, encoded).ok();
+    }
+}
+
+fn build_entries(
+    source: &impl DesktopEntrySource,
+    _frecency: &Arc<FrecencyStore>,
+) -> HashMap<String, CachedEntry> {
+    source
+        .entries()
+        .into_iter()
+        .map(|e| {
+            let id = format!("app-{}:{}", e.name.as_str(), e.exec.as_str());
+            let keywords_lc = e.keywords.iter().map(|k| k.to_lowercase()).collect();
+            #[cfg(target_os = "linux")]
+            let icon = e
+                .icon
+                .as_ref()
+                .and_then(|p| linux::resolve_icon_path(p.as_str()));
+            #[cfg(not(target_os = "linux"))]
+            let icon: Option<String> = None;
+            let exec = e.exec.as_str().to_string();
+            let cached = CachedEntry {
+                id: id.clone(),
+                keywords_lc,
+                category: e.category,
+                icon,
+                exec,
+                name: e.name,
+            };
+            (id, cached)
+        })
+        .collect()
 }
 
 // --- Plugin ---
 
 pub struct AppsPlugin {
-    entries: HashMap<String, CachedEntry>,
+    entries: Arc<RwLock<HashMap<String, CachedEntry>>>,
     frecency: Arc<FrecencyStore>,
 }
 
 impl AppsPlugin {
-    pub fn new(source: impl DesktopEntrySource, frecency: Arc<FrecencyStore>) -> Self {
-        let entries = source
-            .entries()
-            .into_iter()
-            .map(|e| {
-                let id = format!("app-{}", e.name.as_str());
-                let keywords_lc = e.keywords.iter().map(|k| k.to_lowercase()).collect();
-                #[cfg(target_os = "linux")]
-                let icon = e
-                    .icon
-                    .as_ref()
-                    .and_then(|p| linux::resolve_icon_path(p.as_str()));
-                #[cfg(not(target_os = "linux"))]
-                let icon: Option<String> = None;
-                let exec = e.exec.as_str().to_string();
-                let store = Arc::clone(&frecency);
-                let record_id = id.clone();
-                let on_select: Arc<dyn Fn() + Send + Sync> = Arc::new(move || {
-                    store.record(&record_id);
-                });
-                let cached = CachedEntry {
-                    id: id.clone(),
-                    keywords_lc,
-                    category: e.category,
-                    icon,
-                    exec,
-                    on_select,
-                    name: e.name,
-                };
-                (id, cached)
-            })
-            .collect();
+    pub fn new(source: impl DesktopEntrySource + 'static, frecency: Arc<FrecencyStore>) -> Self {
+        Self::new_impl(source, frecency, cache_path())
+    }
+
+    fn new_impl(
+        source: impl DesktopEntrySource + 'static,
+        frecency: Arc<FrecencyStore>,
+        cp: Option<PathBuf>,
+    ) -> Self {
+        let cached = cp.as_deref().and_then(load_from_path);
+
+        let entries = if let Some(from_cache) = cached {
+            // Serve cache immediately; refresh in background.
+            let map = Arc::new(RwLock::new(from_cache));
+            let entries_bg = Arc::clone(&map);
+            let frecency_bg = Arc::clone(&frecency);
+            let cp_bg = cp.clone();
+            std::thread::spawn(move || {
+                let fresh = build_entries(&source, &frecency_bg);
+                if let Some(path) = cp_bg {
+                    save_to_path(&path, &fresh);
+                }
+                *entries_bg.write().unwrap() = fresh;
+            });
+            map
+        } else {
+            // No cache: build synchronously, then persist.
+            let initial = build_entries(&source, &frecency);
+            if let Some(path) = &cp {
+                save_to_path(path, &initial);
+            }
+            Arc::new(RwLock::new(initial))
+        };
+
         Self { entries, frecency }
     }
+
+    #[cfg(test)]
+    fn new_for_test(
+        source: impl DesktopEntrySource + 'static,
+        frecency: Arc<FrecencyStore>,
+    ) -> Self {
+        Self::new_impl(source, frecency, None)
+    }
 }
 
 fn initials(name_lc: &str) -> String {
@@ -170,14 +271,19 @@ impl Plugin for AppsPlugin {
         "apps"
     }
 
+    fn on_selected(&self, id: &ResultId) {
+        self.frecency.record(id.as_str());
+    }
+
     async fn search(&self, query: &str) -> Vec<SearchResult> {
+        let entries = self.entries.read().unwrap();
         if query.is_empty() {
             return self
                 .frecency
                 .top_ids(5)
                 .iter()
                 .filter_map(|id| {
-                    let e = self.entries.get(id)?;
+                    let e = entries.get(id)?;
                     let score = self.frecency.frecency_score(id).max(1);
                     Some(SearchResult {
                         id: ResultId::new(id),
@@ -186,14 +292,13 @@ impl Plugin for AppsPlugin {
                         icon: e.icon.clone(),
                         score: Score::new(score),
                         action: LaunchAction::SpawnProcess(e.exec.clone()),
-                        on_select: Some(Arc::clone(&e.on_select)),
                     })
                 })
                 .collect();
         }
 
         let query_lc = query.to_lowercase();
-        self.entries
+        entries
             .values()
             .filter_map(|e| {
                 let score = score_match(e.name.as_str(), query).or_else(|| {
@@ -209,7 +314,6 @@ impl Plugin for AppsPlugin {
                     icon: e.icon.clone(),
                     score: Score::new(score),
                     action: LaunchAction::SpawnProcess(e.exec.clone()),
-                    on_select: Some(Arc::clone(&e.on_select)),
                 })
             })
             .collect()
@@ -283,7 +387,7 @@ mod tests {
 
     #[tokio::test]
     async fn apps_prefix_match() {
-        let p = AppsPlugin::new(
+        let p = AppsPlugin::new_for_test(
             MockSource::with(vec![("Firefox", "firefox")]),
             ephemeral_frecency(),
         );
@@ -293,7 +397,7 @@ mod tests {
 
     #[tokio::test]
     async fn apps_no_match_returns_empty() {
-        let p = AppsPlugin::new(
+        let p = AppsPlugin::new_for_test(
             MockSource::with(vec![("Firefox", "firefox")]),
             ephemeral_frecency(),
         );
@@ -302,7 +406,7 @@ mod tests {
 
     #[tokio::test]
     async fn apps_empty_query_no_frecency_returns_empty() {
-        let p = AppsPlugin::new(
+        let p = AppsPlugin::new_for_test(
             MockSource::with(vec![("Firefox", "firefox")]),
             ephemeral_frecency(),
         );
@@ -316,7 +420,7 @@ mod tests {
     }
 
     #[test]
-    fn score_match_exact_beats_prefix_beats_abbrev_beats_substr() {
+    fn score_match_exact_beats_prefix() {
         let exact = score_match("firefox", "firefox");
         let prefix = score_match("firefox", "fire");
         let abbrev = score_match("gnu firefox", "gf");
@@ -330,7 +434,7 @@ mod tests {
 
     #[tokio::test]
     async fn apps_abbreviation_match() {
-        let p = AppsPlugin::new(
+        let p = AppsPlugin::new_for_test(
             MockSource::with(vec![("Visual Studio Code", "code")]),
             ephemeral_frecency(),
         );
@@ -342,7 +446,7 @@ mod tests {
 
     #[tokio::test]
     async fn apps_keyword_match() {
-        let p = AppsPlugin::new(
+        let p = AppsPlugin::new_for_test(
             MockSource::with_keywords(vec![("Code", "code", vec!["editor", "ide"])]),
             ephemeral_frecency(),
         );
@@ -353,7 +457,7 @@ mod tests {
 
     #[tokio::test]
     async fn apps_fuzzy_typo_match() {
-        let p = AppsPlugin::new(
+        let p = AppsPlugin::new_for_test(
             MockSource::with(vec![("Firefox", "firefox")]),
             ephemeral_frecency(),
         );
@@ -374,7 +478,7 @@ mod tests {
 
     #[tokio::test]
     async fn apps_category_appears_in_description() {
-        let p = AppsPlugin::new(
+        let p = AppsPlugin::new_for_test(
             MockSource::with_categories(vec![("Code", "code", "Text Editor")]),
             ephemeral_frecency(),
         );
@@ -385,10 +489,10 @@ mod tests {
     #[tokio::test]
     async fn apps_empty_query_returns_top_frecent() {
         let frecency = ephemeral_frecency();
-        frecency.record("app-Code");
-        frecency.record("app-Code");
-        frecency.record("app-Firefox");
-        let p = AppsPlugin::new(
+        frecency.record("app-Code:code");
+        frecency.record("app-Code:code");
+        frecency.record("app-Firefox:firefox");
+        let p = AppsPlugin::new_for_test(
             MockSource::with(vec![("Firefox", "firefox"), ("Code", "code")]),
             frecency,
         );
@@ -396,4 +500,22 @@ mod tests {
         assert_eq!(results.len(), 2);
         assert_eq!(results[0].title.as_str(), "Code");
     }
+
+    #[test]
+    fn apps_loads_from_cache_when_source_is_empty() {
+        let frecency = ephemeral_frecency();
+        let cache_file =
+            std::env::temp_dir().join(format!("k-launcher-test-{}.bin", std::process::id()));
+
+        // Build entries from a real source and save to temp path
+        let source = MockSource::with(vec![("Firefox", "firefox")]);
+        let entries = build_entries(&source, &frecency);
+        save_to_path(&cache_file, &entries);
+
+        // Load from temp path — should contain Firefox
+        let loaded = load_from_path(&cache_file).unwrap();
+        assert!(loaded.contains_key("app-Firefox:firefox"));
+
+        std::fs::remove_file(&cache_file).ok();
+    }
 }

crates/plugins/plugin-calc/src/lib.rs

@@ -90,7 +90,6 @@ impl Plugin for CalcPlugin {
                     icon: None,
                     score: Score::new(90),
                     action: LaunchAction::CopyToClipboard(value_str),
-                    on_select: None,
                 }]
             }
             _ => vec![],

crates/plugins/plugin-cmd/src/lib.rs

@@ -36,7 +36,6 @@ impl Plugin for CmdPlugin {
             icon: None,
             score: Score::new(95),
             action: LaunchAction::SpawnInTerminal(cmd.to_string()),
-            on_select: None,
         }]
     }
 }

crates/plugins/plugin-files/src/lib.rs

@@ -71,21 +71,19 @@ impl Plugin for FilesPlugin {
                     .unwrap_or(false)
             })
             .take(20)
-            .enumerate()
-            .map(|(i, entry)| {
+            .map(|entry| {
                 let full_path = entry.path();
                 let name = entry.file_name().to_string_lossy().to_string();
                 let is_dir = full_path.is_dir();
                 let title = if is_dir { format!("{name}/") } else { name };
                 let path_str = full_path.to_string_lossy().to_string();
                 SearchResult {
-                    id: ResultId::new(format!("file-{i}")),
+                    id: ResultId::new(&path_str),
                     title: ResultTitle::new(title),
                     description: Some(path_str.clone()),
                     icon: None,
                     score: Score::new(50),
                     action: LaunchAction::OpenPath(path_str),
-                    on_select: None,
                 }
             })
             .collect()

crates/plugins/plugin-url/src/main.rs

@@ -10,7 +10,7 @@ struct Query {
 #[derive(Serialize)]
 struct Action {
     r#type: &'static str,
-    cmd: String,
+    path: String,
 }
 
 #[derive(Serialize)]
@@ -45,8 +45,8 @@ fn search(query: &str) -> Vec<Result> {
         description: url.clone(),
         score: 95,
         action: Action {
-            r#type: "SpawnProcess",
-            cmd: format!("xdg-open {url}"),
+            r#type: "OpenPath",
+            path: url.clone(),
         },
     }]
 }
@@ -112,7 +112,7 @@ mod tests {
     fn search_returns_result() {
         let results = search("https://example.com");
         assert_eq!(results.len(), 1);
-        assert_eq!(results[0].action.cmd, "xdg-open https://example.com");
+        assert_eq!(results[0].action.path, "https://example.com");
     }
 
     #[test]
@@ -124,7 +124,7 @@ mod tests {
     fn result_serializes() {
         let results = search("https://example.com");
         let json = serde_json::to_string(&results).unwrap();
-        assert!(json.contains("SpawnProcess"));
-        assert!(json.contains("xdg-open"));
+        assert!(json.contains("OpenPath"));
+        assert!(json.contains("https://example.com"));
     }
 }