Add breadgreet session picker for installed Wayland sessions

List .desktop sessions from the existing scan, pre-select bos when
present (else the first entry), and pass the chosen Exec= argv to
greetd StartSession.

README.md

@@ -43,7 +43,7 @@ breadlock/
 
 - **Protocol**: [`greetd_ipc`](https://crates.io/crates/greetd_ipc) (greetd's own crate) over the Unix socket at `$GREETD_SOCK`: `CreateSession` → answer each `AuthMessage` via `PostAuthMessageResponse` → `StartSession` hands the resolved session command to `greetd`, which execs it and owns the VT switch away.
 - **UI**: GTK4 + [relm4](https://relm4.org/), matching breadbar's stack — **without** `gtk4-layer-shell`. `greetd` hosts the greeter under a single-client kiosk compositor (`cage -s`), which already fullscreens its one client, so layer-shell's multi-surface/anchor semantics don't apply. Confirmed against ReGreet's real dependency list, which has no layer-shell dependency either.
-- **Sessions**: scans `/usr/share/wayland-sessions` and `/usr/share/xsessions` for `.desktop` entries and auto-selects the configured default (or the only one found). BOS ships one session today, so there's no picker UI in v1 — a natural v2 addition if that changes.
+- **Sessions**: scans `/usr/share/wayland-sessions` and `/usr/share/xsessions` for `.desktop` entries and shows a keyboard-accessible picker. The configured default (compiled-in: `bos`) is pre-selected when that stem exists; otherwise the first discovered session. `StartSession` is the chosen entry's `Exec=` argv.
 
 ## Config
 

breadgreet.example.toml

@@ -20,7 +20,8 @@ family = "Varela Round"
 # Directories scanned for .desktop session entries, in order.
 wayland_dirs = ["/usr/share/wayland-sessions"]
 xsessions_dirs = ["/usr/share/xsessions"]
-# .desktop file stem (without extension) to auto-select. Falls back to the
+# .desktop file stem (without extension) pre-selected in the picker.
-# first entry found if this isn't present. v1 has no session picker UI —
+# Falls back to the first entry found if this isn't present. BOS ships
-# BOS only ships one session (Hyprland) today.
+# bos.desktop (Exec=bos-session); leaving this as "bos" is what the ISO
-default = "hyprland"
+# config expects so Hyprland's own hyprland.desktop is not picked first.
+default = "bos"

breadgreet/src/config.rs

@@ -15,7 +15,8 @@ pub struct Config {
 pub struct Sessions {
     pub wayland_dirs: Vec<String>,
     pub xsessions_dirs: Vec<String>,
-    /// `.desktop` file stem (without extension) to auto-select.
+    /// `.desktop` file stem (without extension) to pre-select in the picker.
+    /// Falls back to the first discovered session if this stem is missing.
     pub default: String,
 }
 
@@ -24,7 +25,7 @@ impl Default for Sessions {
         Self {
             wayland_dirs: vec!["/usr/share/wayland-sessions".to_string()],
             xsessions_dirs: vec!["/usr/share/xsessions".to_string()],
-            default: "hyprland".to_string(),
+            default: "bos".to_string(),
         }
     }
 }
@@ -58,6 +59,6 @@ mod tests {
         let s = Sessions::default();
         assert_eq!(s.wayland_dirs, vec!["/usr/share/wayland-sessions"]);
         assert_eq!(s.xsessions_dirs, vec!["/usr/share/xsessions"]);
-        assert_eq!(s.default, "hyprland");
+        assert_eq!(s.default, "bos");
     }
 }

breadgreet/src/main.rs

@@ -37,6 +37,8 @@ enum AppInput {
     Outcome(Outcome),
     Error(String),
     SessionStarted,
+    /// Picker changed; `u32::MAX` (`INVALID_LIST_POSITION`) is ignored.
+    SessionSelected(u32),
 }
 
 struct App {
@@ -45,7 +47,8 @@ struct App {
     entry: gtk4::Entry,
     stage: Stage,
     username: String,
-    session: Option<sessions::Session>,
+    sessions: Vec<sessions::Session>,
+    selected: usize,
     clock_format: String,
     cmd_tx: mpsc::UnboundedSender<GreetdCommand>,
 }
@@ -78,11 +81,19 @@ impl SimpleComponent for App {
         root.fullscreen();
 
         let config = config::load();
-        let session = sessions::discover(
+        let sessions = sessions::list(
+            &config.sessions.wayland_dirs,
+            &config.sessions.xsessions_dirs,
+        );
+        // Same default rule as `discover()`: configured stem (compiled-in
+        // `bos`), else the first listed session.
+        let selected = sessions::discover(
             &config.sessions.wayland_dirs,
             &config.sessions.xsessions_dirs,
             &config.sessions.default,
-        );
+        )
+        .and_then(|chosen| sessions.iter().position(|s| s.stem == chosen.stem))
+        .unwrap_or(0);
 
         let clock_lbl = gtk4::Label::new(None);
         clock_lbl.add_css_class("login-clock");
@@ -99,17 +110,33 @@ impl SimpleComponent for App {
         let status_lbl = gtk4::Label::new(None);
         status_lbl.add_css_class("login-status");
 
-        let session_lbl = gtk4::Label::new(session.as_ref().map(|s| s.name.as_str()));
+        let session_widget: gtk4::Widget = if sessions.is_empty() {
+            let session_lbl = gtk4::Label::new(Some("No session found — cannot log in"));
             session_lbl.add_css_class("login-session");
-        if session.is_none() {
+            session_lbl.upcast()
-            session_lbl.set_label("No session found — cannot log in");
+        } else {
+            let names: Vec<&str> = sessions.iter().map(|s| s.name.as_str()).collect();
+            let dropdown = gtk4::DropDown::from_strings(&names);
+            dropdown.add_css_class("login-session");
+            dropdown.set_hexpand(true);
+            dropdown.set_focusable(true);
+            dropdown.set_tooltip_text(Some("Session"));
+            dropdown.update_property(&[gtk4::accessible::Property::Label("Session")]);
+            dropdown.set_selected(selected as u32);
+            {
+                let sender = sender.clone();
+                dropdown.connect_selected_notify(move |dd| {
+                    sender.input(AppInput::SessionSelected(dd.selected()));
+                });
             }
+            dropdown.upcast()
+        };
 
         let card = gtk4::Box::new(gtk4::Orientation::Vertical, 8);
         card.add_css_class("login-card");
         card.append(&entry);
         card.append(&status_lbl);
-        card.append(&session_lbl);
+        card.append(&session_widget);
 
         let widgets = view_output!();
         widgets.root_box.append(&clock_lbl);
@@ -127,13 +154,15 @@ impl SimpleComponent for App {
             entry,
             stage: Stage::Username,
             username: String::new(),
-            session,
+            sessions,
+            selected,
             clock_format: config.appearance.clock.format.clone(),
             cmd_tx,
         };
         model
             .clock_lbl
             .set_label(&current_time(&model.clock_format));
+        model.entry.grab_focus();
 
         ComponentParts { model, widgets }
     }
@@ -161,6 +190,12 @@ impl SimpleComponent for App {
                 // nothing left for the greeter to do.
                 self.status_lbl.set_label("Starting session…");
             }
+            AppInput::SessionSelected(idx) => {
+                let idx = idx as usize;
+                if idx < self.sessions.len() {
+                    self.selected = idx;
+                }
+            }
         }
     }
 }
@@ -225,7 +260,7 @@ impl App {
     }
 
     fn start_session(&mut self) {
-        let Some(session) = &self.session else {
+        let Some(session) = self.sessions.get(self.selected) else {
             self.status_lbl.set_label("No session available to start");
             self.status_lbl.add_css_class("error");
             return;

breadgreet/src/sessions.rs

@@ -1,17 +1,45 @@
 //! Session discovery: scans the standard greetd-greeter session directories
-//! for `.desktop` entries. BOS effectively ships one session (Hyprland via
+//! for `.desktop` entries, lists them for the picker, and resolves the
-//! `bos-session`), so v1 has no picker UI — it just auto-selects the
+//! chosen entry's `Exec=` line for `greetd`'s `StartSession`.
-//! configured default (or the only entry found) and resolves its `Exec=`
+//!
-//! line to hand to `greetd`'s `StartSession`.
+//! Default selection matches by `.desktop` file stem (`bos` compiled-in,
+//! overridable via `[sessions].default`). If that stem is missing, the
+//! first entry from `wayland_dirs` then `xsessions_dirs` is used.
 
-use breadlock_ui::desktop_entry::{scan_dir, DesktopEntry};
+use breadlock_ui::desktop_entry::scan_dir;
 use std::path::Path;
 
+#[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Session {
+    /// `.desktop` file stem (`bos` for `bos.desktop`) — used to match
+    /// `[sessions].default`.
+    pub stem: String,
     pub name: String,
     pub exec: Vec<String>,
 }
 
+/// Every installed session, `wayland_dirs` first then `xsessions_dirs`.
+/// Each directory is sorted by stem (see [`scan_dir`]).
+pub fn list(wayland_dirs: &[String], xsessions_dirs: &[String]) -> Vec<Session> {
+    let mut all = Vec::new();
+    for dir in wayland_dirs.iter().chain(xsessions_dirs) {
+        for (stem, entry) in scan_dir(Path::new(dir)) {
+            all.push(Session {
+                stem,
+                name: entry.name,
+                exec: split_exec(&entry.exec),
+            });
+        }
+    }
+    all
+}
+
+/// Index of the configured default stem, or `0` if it is absent. Callers
+/// with an empty list should not use this as a subscript.
+pub fn default_index(sessions: &[Session], default: &str) -> usize {
+    sessions.iter().position(|s| s.stem == default).unwrap_or(0)
+}
+
 /// Scans `wayland_dirs` then `xsessions_dirs` (in that order) and returns
 /// the entry matching `default` (by `.desktop` file stem), falling back to
 /// the first entry found in either directory. `None` if nothing is
@@ -21,20 +49,9 @@ pub fn discover(
     xsessions_dirs: &[String],
     default: &str,
 ) -> Option<Session> {
-    let mut all: Vec<(String, DesktopEntry)> = Vec::new();
+    let all = list(wayland_dirs, xsessions_dirs);
-    for dir in wayland_dirs.iter().chain(xsessions_dirs) {
+    let idx = default_index(&all, default);
-        all.extend(scan_dir(Path::new(dir)));
+    all.into_iter().nth(idx)
-    }
-
-    let chosen = all
-        .iter()
-        .find(|(stem, _)| stem == default)
-        .or_else(|| all.first())?;
-
-    Some(Session {
-        name: chosen.1.name.clone(),
-        exec: split_exec(&chosen.1.exec),
-    })
 }
 
 /// Splits a `.desktop` `Exec=` line into an argv. Only handles plain
@@ -69,26 +86,72 @@ mod tests {
         .is_none());
     }
 
+    fn write_fixture(dir: &std::path::Path, stem: &str, name: &str, exec: &str) {
+        std::fs::write(
+            dir.join(format!("{stem}.desktop")),
+            format!("[Desktop Entry]\nName={name}\nExec={exec}\n"),
+        )
+        .unwrap();
+    }
+
     #[test]
     fn discover_prefers_configured_default_over_first_entry() {
-        let dir = std::env::temp_dir().join("breadgreet-test-sessions-discover");
+        let dir = std::env::temp_dir().join(format!(
+            "breadgreet-test-sessions-discover-{}",
+            std::process::id()
+        ));
         std::fs::create_dir_all(&dir).unwrap();
-        std::fs::write(
+        write_fixture(&dir, "aaa", "A", "a-cmd");
-            dir.join("aaa.desktop"),
+        write_fixture(&dir, "hyprland", "Hyprland", "Hyprland");
-            "[Desktop Entry]\nName=A\nExec=a-cmd\n",
-        )
-        .unwrap();
-        std::fs::write(
-            dir.join("hyprland.desktop"),
-            "[Desktop Entry]\nName=Hyprland\nExec=Hyprland\n",
-        )
-        .unwrap();
 
         let dir_str = dir.to_str().unwrap().to_string();
         let session = discover(&[dir_str], &[], "hyprland").unwrap();
+        assert_eq!(session.stem, "hyprland");
         assert_eq!(session.name, "Hyprland");
         assert_eq!(session.exec, vec!["Hyprland"]);
 
         std::fs::remove_dir_all(&dir).ok();
     }
+
+    #[test]
+    fn list_returns_all_sessions_wayland_then_x() {
+        let pid = std::process::id();
+        let wayland = std::env::temp_dir().join(format!("breadgreet-test-sessions-list-w-{pid}"));
+        let x11 = std::env::temp_dir().join(format!("breadgreet-test-sessions-list-x-{pid}"));
+        std::fs::create_dir_all(&wayland).unwrap();
+        std::fs::create_dir_all(&x11).unwrap();
+        write_fixture(&wayland, "bos", "BOS", "/usr/local/bin/bos-session");
+        write_fixture(&wayland, "hyprland", "Hyprland", "Hyprland");
+        write_fixture(&x11, "openbox", "Openbox", "openbox-session");
+
+        let listed = list(
+            &[wayland.to_str().unwrap().to_string()],
+            &[x11.to_str().unwrap().to_string()],
+        );
+        let stems: Vec<&str> = listed.iter().map(|s| s.stem.as_str()).collect();
+        assert_eq!(stems, vec!["bos", "hyprland", "openbox"]);
+        assert_eq!(listed[0].exec, vec!["/usr/local/bin/bos-session"]);
+
+        std::fs::remove_dir_all(&wayland).ok();
+        std::fs::remove_dir_all(&x11).ok();
+    }
+
+    #[test]
+    fn default_index_prefers_bos_then_first() {
+        let sessions = vec![
+            Session {
+                stem: "aaa".into(),
+                name: "A".into(),
+                exec: vec!["a".into()],
+            },
+            Session {
+                stem: "bos".into(),
+                name: "BOS".into(),
+                exec: vec!["bos-session".into()],
+            },
+        ];
+        assert_eq!(default_index(&sessions, "bos"), 1);
+        assert_eq!(default_index(&sessions, "missing"), 0);
+        assert_eq!(default_index(&[], "bos"), 0);
+    }
 }

breadgreet/src/theme.rs

@@ -16,7 +16,8 @@ fn load_css() -> String {
          .login-entry {{ font-size: 14px; }}\
          .login-status {{ font-size: 12px; opacity: 0.75; margin-top: 8px; }}\
          .login-status.error {{ color: {red}; opacity: 1; }}\
-         .login-session {{ font-size: 12px; opacity: 0.6; margin-top: 12px; }}",
+         .login-session {{ font-size: 12px; opacity: 0.85; margin-top: 12px; }}\
+         dropdown.login-session {{ min-height: 32px; }}",
         bg = p.background,
         surface = p.color0,
         red = p.color1,