Fix greeter session start and login flow

greetd only launches the session after the greeter process exits. Quit
on successful StartSession instead of sitting on "Starting session…"
until SIGTERM.

Empty Secret/Visible answers are Some("") (not PAM cancel). The greetd
actor stays up across connect failure and reconnects. Escape cancels
the conversation. Session env sets XDG_SESSION_TYPE/DESKTOP. .desktop
parsing honors Hidden/NoDisplay/TryExec and quoted Exec=. Invalid TOML
warns instead of failing silent. Font, date, and Ken Burns config match
what the greeter actually draws.

breadgreet/src/sessions.rs

@@ -9,6 +9,12 @@
 use breadlock_ui::desktop_entry::scan_dir;
 use std::path::Path;
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum SessionKind {
+    Wayland,
+    X11,
+}
+
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct Session {
     /// `.desktop` file stem (`bos` for `bos.desktop`) — used to match
@@ -16,22 +22,50 @@ pub struct Session {
     pub stem: String,
     pub name: String,
     pub exec: Vec<String>,
+    /// Which directory list this entry came from — drives `XDG_SESSION_TYPE`.
+    pub kind: SessionKind,
+}
+
+impl Session {
+    /// Environment greetd should apply to the started session.
+    pub fn start_env(&self) -> Vec<String> {
+        let session_type = match self.kind {
+            SessionKind::Wayland => "wayland",
+            SessionKind::X11 => "x11",
+        };
+        let desktop = if self.stem.is_empty() {
+            self.name.as_str()
+        } else {
+            self.stem.as_str()
+        };
+        vec![
+            format!("XDG_SESSION_TYPE={session_type}"),
+            format!("XDG_SESSION_DESKTOP={desktop}"),
+            format!("XDG_CURRENT_DESKTOP={desktop}"),
+        ]
+    }
 }
 
 /// 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) {
+    collect_into(&mut all, wayland_dirs, SessionKind::Wayland);
+    collect_into(&mut all, xsessions_dirs, SessionKind::X11);
+    all
+}
+
+fn collect_into(all: &mut Vec<Session>, dirs: &[String], kind: SessionKind) {
+    for dir in dirs {
         for (stem, entry) in scan_dir(Path::new(dir)) {
             all.push(Session {
                 stem,
                 name: entry.name,
                 exec: split_exec(&entry.exec),
+                kind,
             });
         }
     }
-    all
 }
 
 /// Index of the configured default stem, or `0` if it is absent. Callers
@@ -54,18 +88,67 @@ pub fn discover(
     all.into_iter().nth(idx)
 }
 
-/// Splits a `.desktop` `Exec=` line into an argv. Only handles plain
-/// whitespace-separated commands (BOS's own `hyprland.desktop` is
-/// `Exec=Hyprland`) — full field-code (`%f`, `%u`, …) and quoting support
-/// isn't needed for a greeter that never launches file-manager-style
-/// entries.
+/// Splits a `.desktop` `Exec=` line into an argv. Double-quoted arguments
+/// are one token (Freedesktop Exec quoting). Whole-argument field codes
+/// (`%f`, `%F`, …) are dropped; `%%` is a literal `%`.
 fn split_exec(exec: &str) -> Vec<String> {
-    exec.split_whitespace()
-        .filter(|arg| !arg.starts_with('%'))
-        .map(str::to_string)
+    tokenize_exec(exec)
+        .into_iter()
+        .filter(|arg| !is_field_code(arg))
+        .map(|arg| unescape_percent(&arg))
+        .filter(|arg| !arg.is_empty())
         .collect()
 }
 
+fn tokenize_exec(exec: &str) -> Vec<String> {
+    let mut args = Vec::new();
+    let mut current = String::new();
+    let mut in_quote = false;
+    let mut chars = exec.chars().peekable();
+
+    while let Some(c) = chars.next() {
+        match c {
+            '"' => in_quote = !in_quote,
+            '\\' if in_quote => {
+                if let Some(n) = chars.next() {
+                    current.push(n);
+                }
+            }
+            c if c.is_whitespace() && !in_quote => {
+                if !current.is_empty() {
+                    args.push(std::mem::take(&mut current));
+                }
+            }
+            _ => current.push(c),
+        }
+    }
+    if !current.is_empty() {
+        args.push(current);
+    }
+    args
+}
+
+fn is_field_code(arg: &str) -> bool {
+    matches!(
+        arg,
+        "%f" | "%F" | "%u" | "%U" | "%d" | "%D" | "%n" | "%N" | "%i" | "%c" | "%k" | "%v" | "%m"
+    )
+}
+
+fn unescape_percent(arg: &str) -> String {
+    let mut out = String::with_capacity(arg.len());
+    let mut chars = arg.chars().peekable();
+    while let Some(c) = chars.next() {
+        if c == '%' && chars.peek() == Some(&'%') {
+            chars.next();
+            out.push('%');
+        } else {
+            out.push(c);
+        }
+    }
+    out
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -76,6 +159,20 @@ mod tests {
         assert_eq!(split_exec("gnome-session %U"), vec!["gnome-session"]);
     }
 
+    #[test]
+    fn split_exec_quoted_arguments() {
+        assert_eq!(
+            split_exec(r#"wrapper "my session" --flag"#),
+            vec!["wrapper", "my session", "--flag"]
+        );
+    }
+
+    #[test]
+    fn split_exec_double_percent_is_literal() {
+        assert_eq!(split_exec("echo %%"), vec!["echo", "%"]);
+        assert_eq!(split_exec(r#"echo "100%%""#), vec!["echo", "100%"]);
+    }
+
     #[test]
     fn discover_returns_none_when_no_directories_exist() {
         assert!(discover(
@@ -109,6 +206,7 @@ mod tests {
         assert_eq!(session.stem, "hyprland");
         assert_eq!(session.name, "Hyprland");
         assert_eq!(session.exec, vec!["Hyprland"]);
+        assert_eq!(session.kind, SessionKind::Wayland);
 
         std::fs::remove_dir_all(&dir).ok();
     }
@@ -131,6 +229,23 @@ mod tests {
         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"]);
+        assert_eq!(listed[0].kind, SessionKind::Wayland);
+        assert_eq!(listed[2].kind, SessionKind::X11);
+        assert!(
+            listed[2]
+                .start_env()
+                .contains(&"XDG_SESSION_TYPE=x11".to_string())
+        );
+        assert!(
+            listed[0]
+                .start_env()
+                .contains(&"XDG_SESSION_TYPE=wayland".to_string())
+        );
+        assert!(
+            listed[0]
+                .start_env()
+                .contains(&"XDG_SESSION_DESKTOP=bos".to_string())
+        );
 
         std::fs::remove_dir_all(&wayland).ok();
         std::fs::remove_dir_all(&x11).ok();
@@ -143,11 +258,13 @@ mod tests {
                 stem: "aaa".into(),
                 name: "A".into(),
                 exec: vec!["a".into()],
+                kind: SessionKind::Wayland,
             },
             Session {
                 stem: "bos".into(),
                 name: "BOS".into(),
                 exec: vec!["bos-session".into()],
+                kind: SessionKind::Wayland,
             },
         ];
         assert_eq!(default_index(&sessions, "bos"), 1);