fix: power buttons via systemctl, single greeter window (v0.8.7)

Reboot/shutdown buttons always failed: power.rs called `loginctl
reboot|poweroff`, but loginctl has no such verbs (systemd 260) — those
belong to systemctl. moonlock/moonset already used systemctl; moongreet
was the outlier. Switch to `systemctl --no-ask-password reboot|poweroff`.

The multi-monitor greeter gave Exclusive keyboard only to the first
monitor's window, so a user focused on any other output could not type
the password. Drop the per-monitor loop + hotplug; create one window on
the focused output (no set_monitor) with Exclusive keyboard.

Polkit rule kept as a harmless safety net (it was never the blocker;
CanReboot returns yes). The missing journal errors were not a logging
bug — they were lost to a hard power-cut before journald synced.

CLAUDE.md

@@ -40,12 +40,12 @@ cd pkg && makepkg -sf && sudo pacman -U moongreet-git-<version>-x86_64.pkg.tar.z
 - `ipc.rs` — greetd Socket-Kommunikation (4-byte LE header + JSON)
 - `users.rs` — Benutzer aus /etc/passwd, Avatare (AccountsService + ~/.face), Symlink-Rejection
 - `sessions.rs` — Wayland/X11 Sessions aus .desktop Files
-- `power.rs` — Reboot/Shutdown via loginctl
+- `power.rs` — Reboot/Shutdown via systemctl (`--no-ask-password`)
 - `i18n.rs` — Locale-Erkennung (LANG / /etc/locale.conf) und String-Tabellen (DE/EN), alle UI- und Login-Fehlermeldungen
 - `fingerprint.rs` — fprintd D-Bus Probe (gio::DBusProxy) — Geräteerkennung und Enrollment-Check für UI-Feedback
 - `config.rs` — TOML-Config ([appearance] background, gtk-theme, fingerprint-enabled) + Wallpaper-Fallback + Blur-Validierung (finite, clamp 0–200)
 - `greeter.rs` — GTK4 UI (Overlay-Layout), Login-Flow via greetd IPC (Multi-Stage-Auth für fprintd), Faillock-Warnung, Avatar-Cache, Last-User/Last-Session Persistence (0o700 Dirs, 0o600 Files)
-- `main.rs` — Entry Point, GTK App, Layer Shell Setup, Multi-Monitor mit Hotplug via `items-changed` auf Monitor-ListModel (one greeter window per monitor, first gets keyboard), systemd-journal-logger
+- `main.rs` — Entry Point, GTK App, Layer Shell Setup, ein Greeter-Fenster auf dem fokussierten Output (kein `set_monitor`), `KeyboardMode::Exclusive`, systemd-journal-logger
 - `resources/style.css` — Catppuccin-inspiriertes Theme
 
 ## Design Decisions

Cargo.lock

@@ -575,7 +575,7 @@ dependencies = [
 
 [[package]]
 name = "moongreet"
-version = "0.8.5"
+version = "0.8.7"
 dependencies = [
  "gdk-pixbuf",
  "gdk4",

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "moongreet"
-version = "0.8.5"
+version = "0.8.7"
 edition = "2024"
 description = "A greetd greeter for Wayland with GTK4 and Layer Shell"
 license = "MIT"

DECISIONS.md

@@ -1,5 +1,19 @@
 # Decisions
 
+## 2026-06-02 – Power buttons fixed (loginctl→systemctl) + single greeter window (v0.8.7)
+
+- **Who**: ClaudeCode, Dom
+- **Why**: At the greeter the reboot and shutdown buttons always failed with "Neustart/Herunterfahren fehlgeschlagen". Root cause: `power.rs` invoked `/usr/bin/loginctl reboot|poweroff`, but `loginctl` has no such verbs (systemd 260: `Unknown command verb 'reboot'`, exit 1) — power-management verbs belong to `systemctl`. moonlock and moonset already used `systemctl`; moongreet was the outlier (moonset carried the same bug until Mar 29). The polkit rule shipped in v0.8.3 treated the wrong layer — `CanReboot` returns `yes`, polkit was never the blocker. Separately, the multi-monitor greeter (v0.8.0/v0.8.2) gave `KeyboardMode::Exclusive` to only the first enumerated monitor's window, so on a multi-output setup the user could not type the password when focused on any other output.
+- **Tradeoffs**: Dropping the per-monitor + hotplug windows leaves secondary monitors blank during login; irrelevant for a login screen (input happens on one output). Exclusive keyboard binds input to the single greeter surface regardless of pointer position — the mouse may wander to a blank output but typing always reaches the greeter (chosen over compositor-level pointer confinement). The polkit rule is kept as a harmless safety net for the agent-less greeter session; its misleading "session is inactive" comment was corrected.
+- **How**: (1) `power::reboot`/`shutdown` call `/usr/bin/systemctl --no-ask-password reboot|poweroff` (matches moonlock; `--no-ask-password` fails fast instead of hanging on a missing askpass agent). (2) `main.rs` `activate()` creates one greeter window with no `set_monitor` (compositor places it on the focused output, like moonset) and `KeyboardMode::Exclusive`; the monitor loop, `connect_items_changed` hotplug handler, and the now-unused `glib::clone`/`std::rc::Rc` imports are removed. (3) The missing journal entries were investigated and are **not** a logging bug — the greeter user delivers all priorities to journald (verified live); the two button errors were lost because boot -2 was hard-cut before journald's 5-minute sync.
+
+## 2026-04-24 – Audit LOW fixes: stdout null, utf-8 path, debug value, hidden sessions (v0.8.6)
+
+- **Who**: ClaudeCode, Dom
+- **Why**: Four LOW findings cleared in a single pass. (1) `power::run_command` piped stdout it never read — structurally fragile even though current callers stay well under the pipe buffer. (2) Relative wallpaper paths were resolved via `to_string_lossy`, silently substituting `U+FFFD` for non-UTF-8 bytes and producing a path that cannot be opened. (3) `MOONGREET_DEBUG` escalated log verbosity on mere presence, so an empty variable leaked auth metadata into the journal. (4) `Hidden=true` and `NoDisplay=true` `.desktop` entries appeared in the session dropdown even though they mark disabled or stub sessions.
+- **Tradeoffs**: Gating debug on the literal value `"1"` is slightly stricter than most tools but matches the security-first posture. Filtering Hidden/NoDisplay means legitimately hidden but functional sessions are now unselectable from the greeter — acceptable, that is the convention these keys signal.
+- **How**: (1) `.stdout(Stdio::null())` replaces the unused pipe. (2) `to_string_lossy().to_string()` replaced by `to_str().map(|s| s.to_string())` with a `log::warn!` fallback for non-UTF-8 paths. (3) `match std::env::var("MOONGREET_DEBUG").ok().as_deref()` → `Some("1")` selects Debug, everything else Info. (4) `parse_desktop_file` reads `Hidden=` and `NoDisplay=`, returns `None` if either is `true`.
+
 ## 2026-04-24 – Audit MEDIUM fixes: FP double-init, async avatar, symlink, FD leak (v0.8.5)
 
 - **Who**: ClaudeCode, Dom

config/polkit/50-moongreet-power.rules

@@ -1,5 +1,5 @@
 // ABOUTME: Allow the greeter user to reboot and power off without authentication.
-// ABOUTME: Required because greetd's greeter session is inactive in logind.
+// ABOUTME: Safety net for the agent-less greeter session — no askpass/polkit agent to answer a challenge.
 
 polkit.addRule(function(action, subject) {
     if (subject.user === "greeter" &&

src/config.rs

@@ -68,8 +68,14 @@ pub fn load_config(config_paths: Option<&[PathBuf]>) -> Config {
                                 if bg_path.is_absolute() {
                                     merged.background_path = Some(bg);
                                 } else if let Some(parent) = path.parent() {
-                                    merged.background_path =
-                                        Some(parent.join(&bg).to_string_lossy().to_string());
+                                    let joined = parent.join(&bg);
+                                    match joined.to_str() {
+                                        Some(s) => merged.background_path = Some(s.to_string()),
+                                        None => log::warn!(
+                                            "Ignoring non-UTF-8 background path: {}",
+                                            joined.display()
+                                        ),
+                                    }
                                 }
                             }
                             if let Some(blur) = appearance.background_blur {

src/greeter.rs

@@ -189,7 +189,7 @@ fn render_blurred_texture(
 }
 
 /// Create a Picture widget for the wallpaper background, optionally with GPU blur.
-/// Uses `blur_cache` to compute the blurred texture only once across all monitors.
+/// Uses `blur_cache` to compute the blurred texture only once and reuse it.
 fn create_background_picture(
     texture: &gdk::Texture,
     blur_radius: Option<f32>,

src/main.rs

@@ -1,5 +1,5 @@
 // ABOUTME: Entry point for Moongreet — greetd greeter for Wayland.
-// ABOUTME: Sets up GTK Application, Layer Shell, CSS, and multi-monitor windows.
+// ABOUTME: Sets up GTK Application, Layer Shell, CSS, and a single greeter window.
 
 mod config;
 mod fingerprint;
@@ -11,11 +11,9 @@ mod sessions;
 mod users;
 
 use gdk4 as gdk;
-use glib::clone;
 use gtk4::prelude::*;
 use gtk4::{self as gtk, gio};
 use gtk4_layer_shell::LayerShell;
-use std::rc::Rc;
 fn load_css(display: &gdk::Display) {
     let css_provider = gtk::CssProvider::new();
     css_provider.load_from_resource("/dev/moonarch/moongreet/style.css");
@@ -26,13 +24,11 @@ fn load_css(display: &gdk::Display) {
     );
 }
 
-fn setup_layer_shell(window: &gtk::ApplicationWindow, keyboard: bool, layer: gtk4_layer_shell::Layer) {
+fn setup_layer_shell(window: &gtk::ApplicationWindow, layer: gtk4_layer_shell::Layer) {
     window.init_layer_shell();
     window.set_layer(layer);
     window.set_exclusive_zone(-1);
-    if keyboard {
     window.set_keyboard_mode(gtk4_layer_shell::KeyboardMode::Exclusive);
-    }
     // Anchor to all edges for fullscreen
     window.set_anchor(gtk4_layer_shell::Edge::Top, true);
     window.set_anchor(gtk4_layer_shell::Edge::Bottom, true);
@@ -66,49 +62,15 @@ fn activate(app: &gtk::Application) {
     log::debug!("Layer shell: {use_layer_shell}");
 
     if use_layer_shell {
-        // One greeter window per monitor — only the first gets keyboard input
-        let monitors = display.monitors();
-        log::debug!("Monitor count: {}", monitors.n_items());
-        let mut first = true;
-        for i in 0..monitors.n_items() {
-            if let Some(monitor) = monitors
-                .item(i)
-                .and_then(|obj| obj.downcast::<gdk::Monitor>().ok())
-            {
+        // Single greeter window. No set_monitor — the compositor places it on the
+        // focused output (same as moonset). Exclusive keyboard binds input to this
+        // surface regardless of pointer position; the mouse may wander to other
+        // outputs but typing always reaches the greeter. The previous per-monitor
+        // approach gave keyboard only to the first monitor's window, so a user on
+        // any other output could not type the password.
         let window = greeter::create_greeter_window(bg_texture.as_ref(), &config, &blur_cache, app);
-                setup_layer_shell(&window, first, gtk4_layer_shell::Layer::Top);
-                window.set_monitor(Some(&monitor));
+        setup_layer_shell(&window, gtk4_layer_shell::Layer::Top);
         window.present();
-                first = false;
-            }
-        }
-
-        // Handle monitor hotplug — create greeter windows for newly added monitors
-        // (without keyboard, since the primary monitor already has it)
-        let bg_texture = Rc::new(bg_texture);
-        let config = Rc::new(config);
-        monitors.connect_items_changed(clone!(
-            #[weak]
-            app,
-            #[strong]
-            blur_cache,
-            move |list, position, _removed, added| {
-                for i in position..position + added {
-                    if let Some(monitor) = list
-                        .item(i)
-                        .and_then(|obj| obj.downcast::<gdk::Monitor>().ok())
-                    {
-                        log::debug!("Monitor hotplug: creating greeter window");
-                        let window = greeter::create_greeter_window(
-                            bg_texture.as_ref().as_ref(), &config, &blur_cache, &app,
-                        );
-                        setup_layer_shell(&window, false, gtk4_layer_shell::Layer::Top);
-                        window.set_monitor(Some(&monitor));
-                        window.present();
-                    }
-                }
-            }
-        ));
     } else {
         // No layer shell — single window for development
         let greeter_window = greeter::create_greeter_window(bg_texture.as_ref(), &config, &blur_cache, app);
@@ -127,10 +89,12 @@ fn setup_logging() {
             eprintln!("Failed to create journal logger: {e}");
         }
     }
-    let level = if std::env::var("MOONGREET_DEBUG").is_ok() {
-        log::LevelFilter::Debug
-    } else {
-        log::LevelFilter::Info
+    // Require MOONGREET_DEBUG=1 to raise verbosity. Mere presence (e.g. an
+    // empty value in a session-setup script) must not escalate the journal
+    // to Debug, which leaks socket paths, usernames, and auth round counts.
+    let level = match std::env::var("MOONGREET_DEBUG").ok().as_deref() {
+        Some("1") => log::LevelFilter::Debug,
+        _ => log::LevelFilter::Info,
     };
     log::set_max_level(level);
 }

src/power.rs

@@ -1,4 +1,4 @@
-// ABOUTME: Power actions — reboot and shutdown via loginctl.
+// ABOUTME: Power actions — reboot and shutdown via systemctl.
 // ABOUTME: Wrappers around system commands for the greeter UI.
 
 use std::fmt;
@@ -40,7 +40,9 @@ fn run_command(action: &'static str, program: &str, args: &[&str]) -> Result<(),
     log::debug!("Power action: {action} ({program} {args:?})");
     let mut child = Command::new(program)
         .args(args)
-        .stdout(Stdio::piped())
+        // stdout is never read; piping without draining would deadlock on any
+        // command that writes more than one OS pipe buffer before wait() returns.
+        .stdout(Stdio::null())
         .stderr(Stdio::piped())
         .spawn()
         .map_err(|e| PowerError::CommandFailed {
@@ -97,14 +99,21 @@ fn run_command(action: &'static str, program: &str, args: &[&str]) -> Result<(),
     }
 }
 
-/// Reboot the system via loginctl.
+/// Reboot the system via systemctl.
+///
+/// `--no-ask-password` keeps systemctl from spawning an interactive askpass
+/// agent — the greeter session has none, so without it a denied authorization
+/// would hang instead of failing fast.
 pub fn reboot() -> Result<(), PowerError> {
-    run_command("reboot", "/usr/bin/loginctl", &["reboot"])
+    run_command("reboot", "/usr/bin/systemctl", &["--no-ask-password", "reboot"])
 }
 
-/// Shut down the system via loginctl.
+/// Shut down the system via systemctl.
+///
+/// `--no-ask-password` for the same reason as [`reboot`] — the agent-less
+/// greeter session has nothing to answer an authorization challenge.
 pub fn shutdown() -> Result<(), PowerError> {
-    run_command("shutdown", "/usr/bin/loginctl", &["poweroff"])
+    run_command("shutdown", "/usr/bin/systemctl", &["--no-ask-password", "poweroff"])
 }
 
 #[cfg(test)]

src/sessions.rs

@@ -23,6 +23,8 @@ fn parse_desktop_file(path: &Path, session_type: &str) -> Option<Session> {
     let mut in_section = false;
     let mut name: Option<String> = None;
     let mut exec_cmd: Option<String> = None;
+    let mut hidden = false;
+    let mut no_display = false;
 
     for line in content.lines() {
         let line = line.trim();
@@ -44,9 +46,18 @@ fn parse_desktop_file(path: &Path, session_type: &str) -> Option<Session> {
             && exec_cmd.is_none()
         {
             exec_cmd = Some(value.to_string());
+        } else if let Some(value) = line.strip_prefix("Hidden=") {
+            hidden = value.eq_ignore_ascii_case("true");
+        } else if let Some(value) = line.strip_prefix("NoDisplay=") {
+            no_display = value.eq_ignore_ascii_case("true");
         }
     }
 
+    if hidden || no_display {
+        log::debug!("Skipping {}: Hidden/NoDisplay entry", path.display());
+        return None;
+    }
+
     let name = name.filter(|s| !s.is_empty());
     let exec_cmd = exec_cmd.filter(|s| !s.is_empty());