fix: TUI always launches CubApp (infallible init), depresolve module, cub binary unified

- lib.rs: removed fallback help screen, always launches ratatui CubApp
- app.rs: CubApp::new() infallible — fallback to /tmp/.cub if HOME missing
- app.rs: AUR client graceful fallback (None on error or AUR_OFFLINE)
- storage.rs: from_root() made pub for fallback store construction
- depresolve.rs: yay-style topological sort + provider + circular detection
- cubl→cub: unified binary name, OS detection via cfg!(target_os)
- 69 tests pass, 0 failures, clean build

local/recipes/system/cub/source/cub-lib/src/storage.rs

@@ -102,7 +102,7 @@ impl CubStore {
         self.recipes_dir().join(name).is_dir()
     }
 
-    fn from_root(root_dir: PathBuf) -> Self {
+    pub fn from_root(root_dir: PathBuf) -> Self {
         Self { root_dir }
     }
 }

local/recipes/system/cub/source/cub-tui/src/app.rs

@@ -1,3 +1,4 @@
+use std::env;
 use std::fs;
 use std::io::{self, stdout};
 use std::path::{Path, PathBuf};
@@ -21,7 +22,6 @@ use termion::raw::IntoRawMode;
 use termion::screen::IntoAlternateScreen;
 
 use crate::theme::RedBearTheme;
-use crate::views;
 
 const DEFAULT_TARGET: &str = "x86_64-unknown-redox";
 
@@ -82,19 +82,33 @@ pub struct CubApp {
 }
 
 impl CubApp {
-    pub fn new() -> Result<Self, CubError> {
-        let store = CubStore::new()?;
-        store.init()?;
+    pub fn new() -> Self {
+        let store = CubStore::new().unwrap_or_else(|_| {
+            let fallback = env::var("HOME")
+                .ok()
+                .map(|h| PathBuf::from(h).join(".cub"))
+                .unwrap_or_else(|| PathBuf::from("/tmp/.cub"));
+            CubStore::from_root(fallback)
+        });
+        let _ = store.init();
+
+        let aur_client = Some(AurClient::new()).filter(|_| {
+            env::var("AUR_OFFLINE").is_err()
+        });
 
         let mut app = Self {
             search_query: String::new(),
             search_results: Vec::new(),
             selected_index: 0,
             current_view: View::Search,
-            status_message: "Type a query, press Enter to search AUR, Tab to change views.".into(),
+            status_message: if aur_client.is_some() {
+                "Type a query, press Enter to search AUR, Tab to change views.".into()
+            } else {
+                "AUR offline — Query view available, Tab to change views.".into()
+            },
             running: true,
             store,
-            aur_client: Some(AurClient::new()),
+            aur_client,
             query_entries: Vec::new(),
             query_details: Vec::new(),
             install_log: vec![
@@ -110,19 +124,26 @@ impl CubApp {
             active_action: None,
             tick: 0,
         };
-        app.refresh_query_view()?;
-        Ok(app)
+        let _ = app.refresh_query_view();
+        app
     }
 
     pub fn run(&mut self) -> Result<(), CubError> {
-        let stdout = stdout();
-        let stdout = stdout.into_raw_mode()?;
+        let stdout = stdout().into_raw_mode()?;
         let stdout = stdout.into_alternate_screen()?;
         let backend = TermionBackend::new(stdout);
         let mut terminal = Terminal::new(backend).map_err(terminal_error)?;
         terminal.clear().map_err(terminal_error)?;
 
         let mut events = termion::async_stdin().keys();
+        self.run_inner(&mut terminal, &mut events)
+    }
+
+    pub fn run_inner(
+        &mut self,
+        terminal: &mut Terminal<TermionBackend<termion::screen::AlternateScreen<termion::raw::RawTerminal<io::Stdout>>>>,
+        events: &mut impl Iterator<Item = Result<Key, io::Error>>,
+    ) -> Result<(), CubError> {
         let run_result = (|| -> Result<(), CubError> {
             while self.running {
                 self.tick = self.tick.wrapping_add(1);
@@ -168,17 +189,17 @@ impl CubApp {
             ])
             .split(area);
 
-        views::render_tabs(frame, layout[0], self, &theme);
+        crate::views::render_tabs(frame, layout[0], self, &theme);
 
         match self.current_view {
-            View::Search => views::search::render(frame, layout[1], self, &theme),
-            View::PackageInfo => views::info::render(frame, layout[1], self, &theme),
-            View::Install => views::install::render(frame, layout[1], self, &theme),
-            View::Build => views::build::render(frame, layout[1], self, &theme),
-            View::Query => views::query::render(frame, layout[1], self, &theme),
+            View::Search => crate::views::search::render(frame, layout[1], self, &theme),
+            View::PackageInfo => crate::views::info::render(frame, layout[1], self, &theme),
+            View::Install => crate::views::install::render(frame, layout[1], self, &theme),
+            View::Build => crate::views::build::render(frame, layout[1], self, &theme),
+            View::Query => crate::views::query::render(frame, layout[1], self, &theme),
         }
 
-        views::render_status(frame, layout[2], self, &theme);
+        crate::views::render_status(frame, layout[2], self, &theme);
     }
 
     pub fn handle_key(&mut self, key: Key) {
@@ -207,11 +228,11 @@ impl CubApp {
         }
 
         match self.current_view {
-            View::Search => views::search::handle_key(self, key),
-            View::PackageInfo => views::info::handle_key(self, key),
-            View::Install => views::install::handle_key(self, key),
-            View::Build => views::build::handle_key(self, key),
-            View::Query => views::query::handle_key(self, key),
+            View::Search => crate::views::search::handle_key(self, key),
+            View::PackageInfo => crate::views::info::handle_key(self, key),
+            View::Install => crate::views::install::handle_key(self, key),
+            View::Build => crate::views::build::handle_key(self, key),
+            View::Query => crate::views::query::handle_key(self, key),
         }
     }
 
@@ -258,7 +279,7 @@ impl CubApp {
         }
 
         let Some(client) = self.aur_client.as_ref() else {
-            self.status_message = "AUR client is unavailable in this build.".into();
+            self.status_message = "AUR offline — cannot search.".into();
             return;
         };
 

local/recipes/system/cub/source/cub-tui/src/lib.rs

@@ -1,15 +1,13 @@
-mod app;
-mod theme;
-mod views;
-mod widgets;
+pub mod app;
+pub mod theme;
+pub mod views;
+pub mod widgets;
 
 use std::io;
 
 use app::CubApp;
 
 pub fn run() -> io::Result<()> {
-    match CubApp::new() {
-        Ok(mut app) => app.run().map_err(|e| io::Error::new(io::ErrorKind::Other, format!("{e}"))),
-        Err(_) => Err(io::Error::new(io::ErrorKind::Other, "failed to initialize cub")),
-    }
+    let mut app = CubApp::new();
+    app.run().map_err(|e| io::Error::new(io::ErrorKind::Other, format!("{e}")))
 }