Start with defaults when configuration is invalid (#29)

Invalid configuration currently prevents login. Ferese now starts with built-in defaults and shows a notification when the shell is ready, leaving the file untouched. Loading and validation belong to the config module, while the theme module resolves appearance. Validation remains strict, and failed live reloads keep the active settings.

The native Morph regression checks the animated input region and idle frame scheduling while its backing surface stays allocated.

Validation: workspace and Python tests, formatting, Clippy, release build, and isolated Wayland startup/reload and panel-motion tests. Native CI includes the startup regression.

Related: #28.

shell/ferese-shell/src/config.rs

@@ -1,4 +1,5 @@
 use std::fs;
+use std::io::Read;
 use std::path::PathBuf;
 
 use serde::Deserialize;
@@ -349,7 +350,16 @@ fn load_path(path: &std::path::Path) -> Result<ShellConfig, String> {
         Err(error) if error.kind() == std::io::ErrorKind::NotFound => return Ok(ShellConfig::default()),
         Err(error) => return Err(format!("cannot read {}: {error}", path.display())),
     }
-    let source = fs::read_to_string(path).map_err(|error| format!("cannot read {}: {error}", path.display()))?;
+    let mut source = String::new();
+    fs::File::open(path)
+        .and_then(|file| {
+            file.take((ferese_config::file::LIMIT + 1) as u64)
+                .read_to_string(&mut source)
+        })
+        .map_err(|error| format!("cannot read {}: {error}", path.display()))?;
+    if source.len() > ferese_config::file::LIMIT {
+        return Err(format!("{} exceeds 60 KiB", path.display()));
+    }
     parse_source(&source).map_err(|error| format!("invalid configuration in {}: {error}", path.display()))
 }
 
@@ -781,7 +791,7 @@ theme {
     }
 
     #[test]
-    fn startup_rejects_invalid_configuration_without_replacing_it() {
+    fn loader_reports_invalid_configuration_without_replacing_it() {
         let directory = tempfile::tempdir().unwrap();
         let path = directory.path().join("config.kdl");
         let source =
@@ -793,6 +803,10 @@ theme {
         assert_eq!(std::fs::read_to_string(&path).unwrap(), source);
         std::fs::write(&path, "panel main {").unwrap();
         assert!(super::load_path(&path).is_err());
+        let oversized = " ".repeat(ferese_config::file::LIMIT + 1);
+        std::fs::write(&path, &oversized).unwrap();
+        assert!(super::load_path(&path).unwrap_err().contains("60 KiB"));
+        assert_eq!(std::fs::read_to_string(&path).unwrap(), oversized);
     }
 
     #[test]

shell/ferese-shell/src/main.rs

@@ -100,10 +100,16 @@ impl From<panel::PanelGeometry> for BarMetrics {
 }
 
 fn main() -> cosmic::iced::Result {
-    let mut config = config::load().unwrap_or_else(|error| {
-        eprintln!("ferese-shell: {error}; shell was not started");
-        std::process::exit(2);
-    });
+    let (mut config, startup_error) = match config::load() {
+        Ok(config) => (config, None),
+        Err(error) => {
+            eprintln!("ferese-shell: {error}; starting with defaults");
+            let notice = format!(
+                "The shell started with default settings. Your configuration file has not been changed.\n\n{error}"
+            );
+            (ShellConfig::default(), Some(notice))
+        }
+    };
     renderer::configure_shell();
 
     let compositor_wallpaper = std::env::var_os("FERESE_COMPOSITOR_WALLPAPER").is_some();
@@ -133,7 +139,7 @@ fn main() -> cosmic::iced::Result {
         .default_font(shell_font)
         .theme(config.theme.palette().native_theme());
 
-    cosmic::app::run::<FereseShell>(settings, (config, wallpaper))
+    cosmic::app::run::<FereseShell>(settings, (config, wallpaper, startup_error))
 }
 
 type WallpaperLoad = cosmic::iced::futures::channel::oneshot::Receiver<Result<image::Handle, String>>;
@@ -158,6 +164,7 @@ struct FereseShell {
     calendar_offset: i32,
     status_error: Option<status::ActionError>,
     theme_error: Option<String>,
+    pending_config_error: Option<String>,
     menu: Option<status_ui::OpenMenu>,
     system_modal: Option<system_modal::SystemModal>,
     display_mode: display_mode::Model,
@@ -267,7 +274,7 @@ enum Message {
 
 impl cosmic::Application for FereseShell {
     type Executor = cosmic::executor::Default;
-    type Flags = (ShellConfig, Option<WallpaperLoad>);
+    type Flags = (ShellConfig, Option<WallpaperLoad>, Option<String>);
     type Message = Message;
 
     const APP_ID: &'static str = APP_ID;
@@ -280,7 +287,13 @@ impl cosmic::Application for FereseShell {
         &mut self.core
     }
 
-    fn init(core: Core, (config, wallpaper): Self::Flags) -> (Self, Task<Self::Message>) {
+    fn init(core: Core, (config, wallpaper, startup_error): Self::Flags) -> (Self, Task<Self::Message>) {
+        let control = ShellControl::connect()
+            .map_err(|error| eprintln!("ferese-shell: shell control unavailable: {error}"))
+            .ok();
+        // The compositor reports the complete configuration error through its
+        // accepted-theme snapshot. Use the local warning only when standalone.
+        let pending_config_error = if control.is_none() { startup_error } else { None };
         let app = Self {
             core,
             notifications: notifications::Center::new(config.notifications.clone(), config.animations),
@@ -292,6 +305,7 @@ impl cosmic::Application for FereseShell {
             calendar_offset: 0,
             status_error: None,
             theme_error: None,
+            pending_config_error,
             menu: None,
             system_modal: None,
             display_mode: display_mode::Model::default(),
@@ -302,11 +316,7 @@ impl cosmic::Application for FereseShell {
             render: rendering::Rendering::new(&config),
             config,
             wallpaper: None,
-            control: ShellControl::connect()
-                .map_err(|error| {
-                    eprintln!("ferese-shell: shell control unavailable: {error}");
-                })
-                .ok(),
+            control,
             snapshot: ShellSnapshot::default(),
             workspace_ui: Default::default(),
             overview_active: false,
@@ -366,7 +376,7 @@ impl cosmic::Application for FereseShell {
     }
 
     fn update(&mut self, message: Self::Message) -> Task<Self::Message> {
-        match message {
+        let task = match message {
             Message::HubOpen(id, kind) => self.open_hub(id, kind),
             Message::HubClose(id) => self.close_hub(id),
             Message::HubWorkspaceScroll(id, delta) => self.scroll_hub_workspaces(id, delta),
@@ -471,9 +481,7 @@ impl cosmic::Application for FereseShell {
                 config.apply_theme(&snapshot.presented);
                 config.theme_mode = snapshot.mode;
                 if snapshot.error != self.theme_error {
-                    if let Some(error) = &snapshot.error {
-                        self.notifications.service_error("Theme could not be loaded", error);
-                    }
+                    self.pending_config_error = snapshot.error.clone();
                     self.theme_error = snapshot.error;
                 }
                 self.apply_config(config)
@@ -875,7 +883,9 @@ impl cosmic::Application for FereseShell {
                 }
                 self.dismiss_workspace_tooltip()
             }
-        }
+        };
+        self.flush_config_error();
+        task
     }
 
     fn style(&self) -> Option<cosmic::iced::theme::Style> {
@@ -894,6 +904,17 @@ impl cosmic::Application for FereseShell {
 }
 
 impl FereseShell {
+    fn flush_config_error(&mut self) {
+        if self.notifications.ready
+            && self.outputs.iter().any(|output| !output.hidden)
+            && let Some(error) = self.pending_config_error.take()
+        {
+            eprintln!("ferese-shell: configuration warning: {error}");
+            self.notifications
+                .service_error("Configuration could not be loaded", &error);
+        }
+    }
+
     fn reload_config(&mut self, source: String) -> Task<Message> {
         let config = match config::parse_source(&source) {
             Ok(config) => config,
@@ -1080,6 +1101,7 @@ mod tests {
             calendar_offset: 0,
             status_error: None,
             theme_error: None,
+            pending_config_error: None,
             menu: None,
             system_modal: None,
             display_mode: Default::default(),