fix: handle monitor hotplug for greeter windows (v0.8.2)

Greeter windows were only created at startup. Hotplugged monitors (e.g.
HDMI reconnect) would show no UI. Connect to the monitor ListModel's
items-changed signal to create greeter windows for newly added monitors.

Aligned with moonlock's hotplug fix using the same pattern adapted for
gtk4-layer-shell (ListModel) instead of session-lock (connect_monitor).

.gitea/workflows/update-pkgver.yaml

@@ -0,0 +1,43 @@
+# ABOUTME: Updates pkgver in moonarch-pkgbuilds after a push to main.
+# ABOUTME: Ensures paru detects new versions of this package.
+
+name: Update PKGBUILD version
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  update-pkgver:
+    runs-on: moonarch
+    steps:
+      - name: Checkout source repo
+        run: |
+          git clone --bare http://gitea:3000/nevaforget/greetd-moongreet.git source.git
+          cd source.git
+          PKGVER=$(git describe --long --tags | sed 's/^v//;s/-/.r/;s/-/./')
+          echo "New pkgver: $PKGVER"
+          echo "$PKGVER" > /tmp/pkgver
+
+      - name: Update PKGBUILD
+        run: |
+          PKGVER=$(cat /tmp/pkgver)
+          git clone http://gitea:3000/nevaforget/moonarch-pkgbuilds.git pkgbuilds
+          cd pkgbuilds
+
+          OLD_VER=$(grep '^pkgver=' moongreet-git/PKGBUILD | cut -d= -f2)
+          if [ "$OLD_VER" = "$PKGVER" ]; then
+            echo "pkgver already up to date ($PKGVER)"
+            exit 0
+          fi
+
+          sed -i "s/^pkgver=.*/pkgver=$PKGVER/" moongreet-git/PKGBUILD
+          sed -i "s/^\tpkgver = .*/\tpkgver = $PKGVER/" moongreet-git/.SRCINFO
+          echo "Updated pkgver: $OLD_VER → $PKGVER"
+
+          git config user.name "pkgver-bot"
+          git config user.email "gitea@moonarch.de"
+          git add moongreet-git/PKGBUILD moongreet-git/.SRCINFO
+          git commit -m "chore(moongreet-git): bump pkgver to $PKGVER"
+          git -c http.extraHeader="Authorization: token ${{ secrets.PKGBUILD_TOKEN }}" push

CLAUDE.md

@@ -45,9 +45,9 @@ cd pkg && makepkg -sf && sudo pacman -U moongreet-git-<version>-x86_64.pkg.tar.z
 - `power.rs` — Reboot/Shutdown via loginctl
 - `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
-- `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 (0o600 Permissions)
-- `main.rs` — Entry Point, GTK App, Layer Shell Setup, Multi-Monitor, systemd-journal-logger
+- `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
 - `resources/style.css` — Catppuccin-inspiriertes Theme
 
 ## Design Decisions
@@ -57,13 +57,13 @@ cd pkg && makepkg -sf && sudo pacman -U moongreet-git-<version>-x86_64.pkg.tar.z
 - **Async Login**: `glib::spawn_future_local` + `gio::spawn_blocking` statt raw Threads
 - **Socket-Cancellation**: `Arc<Mutex<Option<UnixStream>>>` + `AtomicBool` für saubere Abbrüche
 - **Avatar-Cache**: `HashMap<String, gdk::Texture>` in `Rc<RefCell<GreeterState>>`
-- **GPU-Blur via GskBlurNode**: `Snapshot::push_blur()` + `GskRenderer::render_texture()` im `connect_realize` Callback — kein CPU-Blur, kein Disk-Cache, kein `image`-Crate
-- **Fingerprint via greetd Multi-Stage PAM**: fprintd D-Bus nur als Probe (Gerät/Enrollment), eigentliche Verifizierung läuft über PAM im greetd-Auth-Loop. `auth_message_type: "secret"` → Passwort, alles andere → `None` (PAM entscheidet). 60s Socket-Timeout bei fprintd.
+- **GPU-Blur via GskBlurNode**: `Snapshot::push_blur()` + `GskRenderer::render_texture()` im `connect_realize` Callback — kein CPU-Blur, kein Disk-Cache, kein `image`-Crate. Blurred Texture wird per `Rc<RefCell<Option<gdk::Texture>>>` über alle Monitore gecacht (1x GPU-Renderpass statt N).
+- **Fingerprint via greetd Multi-Stage PAM**: fprintd D-Bus nur als Probe (Gerät/Enrollment), eigentliche Verifizierung läuft über PAM im greetd-Auth-Loop. `auth_message_type: "secret"` → Passwort, alles andere → `None` (PAM entscheidet). 60s Socket-Timeout bei fprintd. Device-Proxy in `GreeterState` gecacht, Generation-Counter gegen Race Conditions bei schnellem User-Switch.
 - **Symmetrie mit moonlock/moonset**: Gleiche Patterns (i18n, config, users, power, GResource, GPU-Blur)
 - **Session-Validierung**: Relative Pfade erlaubt (greetd löst PATH auf), nur `..`/Null-Bytes werden abgelehnt
 - **GTK-Theme-Validierung**: Nur alphanumerisch + `_-+.` erlaubt, verhindert Path-Traversal über Config
 - **Journal-Logging**: `systemd-journal-logger` statt File-Logging — `journalctl -t moongreet`, Debug-Level per `MOONGREET_DEBUG` Env-Var
-- **File Permissions**: Cache-Dateien 0o600
+- **File Permissions**: Cache-Verzeichnisse 0o700 via `DirBuilder::mode()`, Cache-Dateien 0o600
 - **Testbare Persistence**: `save_*_to`/`load_*_from` Varianten mit konfigurierbarem Pfad für Unit-Tests
 - **Shared Wallpaper Texture**: `gdk::Texture` wird einmal in `load_background_texture()` dekodiert und per Ref-Count an alle Fenster geteilt — vermeidet redundante JPEG-Dekodierung pro Monitor
 - **Wallpaper-Validierung**: GResource-Zweig via `resources_lookup_data()` + `from_bytes()` (kein Abort bei fehlendem Pfad), Dateigröße-Limit 50 MB, non-UTF-8-Pfade → `None`

Cargo.lock

@@ -59,6 +59,12 @@ version = "1.0.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "9330f8b2ff13f34540b44e946ef35111825727b38d33286ef986142615121801"
 
+[[package]]
+name = "cfg_aliases"
+version = "0.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "613afe47fcd5fac7ccf1db93babcb082c5994d996f20b8b159f2ad1658eb5724"
+
 [[package]]
 name = "equivalent"
 version = "1.0.2"
@@ -569,7 +575,7 @@ dependencies = [
 
 [[package]]
 name = "moongreet"
-version = "0.5.3"
+version = "0.8.0"
 dependencies = [
  "gdk-pixbuf",
  "gdk4",
@@ -580,11 +586,25 @@ dependencies = [
  "gtk4",
  "gtk4-layer-shell",
  "log",
+ "nix",
  "serde",
  "serde_json",
  "systemd-journal-logger",
  "tempfile",
  "toml 0.8.23",
+ "zeroize",
+]
+
+[[package]]
+name = "nix"
+version = "0.29.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "71e2746dc3a24dd78b3cfcb7be93368c6de9963d30f43a6a73998a9cf4b17b46"
+dependencies = [
+ "bitflags",
+ "cfg-if",
+ "cfg_aliases",
+ "libc",
 ]
 
 [[package]]
@@ -1124,6 +1144,12 @@ version = "0.8.28"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "3ae8337f8a065cfc972643663ea4279e04e7256de865aa66fe25cec5fb912d3f"
 
+[[package]]
+name = "zeroize"
+version = "1.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b97154e67e32c85465826e8bcc1c59429aaaf107c1e4a9e53c8d8ccd5eff88d0"
+
 [[package]]
 name = "zmij"
 version = "1.0.21"

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "moongreet"
-version = "0.6.0"
+version = "0.8.2"
 edition = "2024"
 description = "A greetd greeter for Wayland with GTK4 and Layer Shell"
 license = "MIT"
@@ -16,11 +16,18 @@ toml = "0.8"
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 graphene-rs = { version = "0.22", package = "graphene-rs" }
+nix = { version = "0.29", features = ["signal"] }
+zeroize = { version = "1", features = ["std"] }
 log = "0.4"
 systemd-journal-logger = "2.2"
 
 [dev-dependencies]
 tempfile = "3"
 
+[profile.release]
+lto = "thin"
+codegen-units = 1
+strip = true
+
 [build-dependencies]
 glib-build-tools = "0.22"

DECISIONS.md

@@ -1,8 +1,50 @@
 # Decisions
 
+## 2026-04-09 – Monitor hotplug via ListModel items-changed
+
+- **Who**: ClaudeCode, Dom
+- **Why**: Greeter windows were only created at startup. If a monitor was hotplugged (e.g. HDMI reconnect), it would show no greeter UI. Aligned with moonlock's hotplug fix (same day).
+- **Tradeoffs**: Hotplugged monitors get greeter windows without keyboard input (keyboard stays on the primary monitor). Acceptable — user can still interact on the primary screen.
+- **How**: Connect to `display.monitors().connect_items_changed()` and create new greeter windows for added monitors. Shared state (config, texture, blur_cache) moved to Rc for the closure.
+
+## 2026-04-08 – Show greeter UI on all monitors instead of just one
+
+- **Who**: ClaudeCode, Dom
+- **Why**: moonlock showed its UI on all monitors via ext-session-lock-v1, but moongreet only showed the login UI on one monitor (compositor-picked) with wallpaper-only windows on the rest. Inconsistent UX across the ecosystem.
+- **Tradeoffs**: Each monitor gets its own full greeter widget tree (slightly more memory), but the UI is lightweight. Screen mirroring (e.g., wl-mirror/screencopy) was considered and rejected — it requires an external process, compositor screencopy support, adds latency, and fights Wayland's per-output model. One-window-per-monitor is the established Wayland pattern (swaylock, hyprlock, moonlock all do this).
+- **How**: Create one `create_greeter_window()` per monitor with `set_monitor()`, only the first gets `KeyboardMode::Exclusive`. Removed `create_wallpaper_window()` (no longer needed). No layer shell fallback keeps single-window mode for development.
+
+## 2026-04-06 – Restore explicit gtk-theme in moongreet config
+
+- **Who**: ClaudeCode, Dom
+- **Why**: GTK4 under greetd does not reliably read `/etc/xdg/gtk-4.0/settings.ini` — likely requires a settings daemon that doesn't run in the greeter session. moongreet fell back to Adwaita/Colloid-default (blue accent) instead of Colloid-Grey-Dark-Catppuccin.
+- **Tradeoffs**: Reverts `094878f` ("Remove gtk-theme from app config, use system-wide GTK settings instead"). Duplicates the theme name between settings.ini and moongreet.toml, but the explicit set via `set_gtk_theme_name()` is the only reliable path in a greetd context.
+- **How**: Added `gtk-theme = "Colloid-Grey-Dark-Catppuccin"` to example config and deployed `/etc/moongreet/moongreet.toml`.
+
+## 2026-04-02 – Replace hardcoded CSS colors with GTK theme variables
+
+- **Who**: ClaudeCode, Dom
+- **Why**: moongreet used hardcoded colors (#1a1a2e, white, #ff6b6b) while moonset already used @theme_bg_color, @theme_fg_color, @error_color etc. Inconsistent across the ecosystem and broke theme flexibility.
+- **Tradeoffs**: Depends on the active GTK theme defining standard color variables. Catppuccin Colloid provides all needed vars (@theme_bg_color, @theme_fg_color, @error_color, @success_color, @theme_selected_bg_color). Fallback behavior if a theme lacks vars is GTK's default colors — acceptable.
+- **How**: Replaced all hardcoded hex/named colors with GTK theme variables. Coordinated change across moongreet, moonlock, and moonset (all three now use identical pattern).
+
+## 2026-03-31 – Fourth audit: power timeout, timing mitigation, release profile, GREETD_SOCK caching
+
+- **Who**: ClaudeCode, Dom
+- **Why**: Fourth triple audit found moongreet power.rs had no timeout on loginctl (greeter could freeze), username enumeration via timing differential, GREETD_SOCK re-read on every login, missing release profile, and missing GResource compression.
+- **Tradeoffs**: 500ms minimum login response time adds slight delay on fast auth but prevents timing-based username enumeration. Power timeout (30s + SIGKILL) matches moonset pattern — aggressive but prevents greeter freeze.
+- **How**: (1) power.rs adapted from moonset with 30s timeout + SIGKILL (nix dependency added). (2) 500ms min response floor in attempt_login via Instant + glib::timeout_future. (3) GREETD_SOCK cached in GreeterState at startup. (4) `[profile.release]` with LTO, codegen-units=1, strip. (5) `compressed="true"` on GResource entries. (6) SYNC comments on duplicated blur/background functions.
+
+## 2026-03-30 – Full audit fix: security, quality, performance (v0.6.2)
+
+- **Who**: ClaudeCode, Dom
+- **Why**: Three parallel audits (security, code quality, performance) identified 10 actionable findings across the codebase — from world-readable cache dirs to a GPU blur geometry bug to a race condition in fingerprint probing.
+- **Tradeoffs**: `too_many_arguments` Clippy warnings suppressed with `#[allow]` rather than introducing a `UiWidgets` struct — GTK's `clone!` macro with `#[weak]` refs requires individual widget parameters, a struct would fight the idiom. Async avatar loading skipped because `Pixbuf` is `!Send`; cache already prevents repeat loads. TOCTOU socket pre-check removed entirely — `connect()` in login_worker already handles errors, the `metadata()` check gave false security guarantees.
+- **How**: Cache dirs use `DirBuilder::mode(0o700)` instead of `create_dir_all`. Blur config clamped to `0.0..=200.0` with `is_finite()` guard. Blur texture cached in `Rc<RefCell<Option<gdk::Texture>>>` across monitors. FingerprintProbe device proxy cached in `GreeterState` with generation counter to prevent stale async writes. GPU blur geometry fixed (`-pad` origin shift instead of texture stretching). `is_valid_gtk_theme` extracted as testable function. 9 new tests.
+
 ## 2026-03-29 – Fingerprint authentication via greetd multi-stage PAM
 
-- **Who**: Ragnar, Dom
+- **Who**: ClaudeCode, Dom
 - **Why**: moonlock supports fprintd but moongreet rejected multi-stage auth. Users with enrolled fingerprints couldn't use them at the login screen.
 - **Tradeoffs**: Direct fprintd D-Bus verification (like moonlock) can't start a greetd session — greetd controls session creation via PAM. Using greetd multi-stage means PAM decides the auth order (fingerprint first, then password fallback), not truly parallel. Acceptable — matches standard pam_fprintd behavior.
 - **How**: Replace single-pass auth with a loop over auth_message rounds. Secret prompts get the password, non-secret prompts (fprintd) get None and block until PAM resolves. fprintd D-Bus probe (gio::DBusProxy) only for UI — detecting device availability and enrolled fingers. 60s socket timeout when fingerprint available. Config option `fingerprint-enabled` (default true).
@@ -16,7 +58,7 @@
 
 ## 2026-03-28 – GPU blur via GskBlurNode replaces CPU blur
 
-- **Who**: Ragnar, Dom
+- **Who**: ClaudeCode, Dom
 - **Why**: CPU-side Gaussian blur (`image` crate) blocked the GTK main thread for 500ms–2s on 4K wallpapers at cold cache. Disk cache and async orchestration added significant complexity.
 - **Tradeoffs**: GPU blur quality is slightly different (box-blur approximation vs true Gaussian), acceptable for wallpaper backgrounds. Removes `image` crate dependency entirely (~15 transitive crates eliminated). No disk cache needed.
 - **How**: `Snapshot::push_blur()` + `GskRenderer::render_texture()` on `connect_realize`. Blur happens once on the GPU when the widget gets its renderer, producing a concrete `gdk::Texture`. Zero startup latency. Symmetric with moonlock and moonset.

README.md

@@ -12,10 +12,13 @@ Part of the Moonarch ecosystem.
 - **Last user/session** — Remembered in `/var/cache/moongreet/`
 - **Power actions** — Reboot / Shutdown via `loginctl`
 - **Layer Shell** — Fullscreen via gtk4-layer-shell (TOP layer)
-- **Multi-monitor** — Greeter on primary, wallpaper on all monitors
+- **Multi-monitor + hotplug** — Full greeter UI on all monitors (keyboard input on first), hotplugged monitors get windows automatically
+- **GPU blur** — Background blur via GskBlurNode (shared cache across monitors)
 - **i18n** — German and English (auto-detected from system locale)
 - **Faillock warning** — Warns after 2 failed attempts, locked message after 3
 - **Fingerprint** — fprintd support via greetd multi-stage PAM (configurable)
+- **Journal logging** — `journalctl -t moongreet`, debug level via `MOONGREET_DEBUG` env var
+- **Password wiping** — Zeroize on drop
 
 ## Requirements
 
@@ -66,8 +69,8 @@ cargo test
 # Build release
 cargo build --release
 
-# Run locally (without greetd, needs LD_PRELOAD for layer-shell)
-LD_PRELOAD=/usr/lib/libgtk4-layer-shell.so ./target/release/moongreet
+# Run locally (without greetd, disables layer-shell)
+MOONGREET_NO_LAYER_SHELL=1 ./target/release/moongreet
 ```
 
 ## License

build.rs

@@ -1,5 +1,5 @@
 // ABOUTME: Build script for compiling GResource bundle.
-// ABOUTME: Bundles style.css, wallpaper.jpg, and default-avatar.svg into the binary.
+// ABOUTME: Bundles style.css and default-avatar.svg into the binary.
 
 fn main() {
     glib_build_tools::compile_resources(

config/moongreet.toml

@@ -4,5 +4,7 @@
 [appearance]
 # Absolute path to wallpaper image
 background = "/usr/share/backgrounds/wallpaper.jpg"
-# GTK theme for the greeter UI
-gtk-theme = "Colloid-Catppuccin"
+
+# GTK theme name — must match a directory in /usr/share/themes/
+# Required because GTK4 under greetd does not reliably read settings.ini
+gtk-theme = "Colloid-Grey-Dark-Catppuccin"

pkg/PKGBUILD

@@ -4,7 +4,7 @@
 # Maintainer: Dominik Kressler
 
 pkgname=moongreet-git
-pkgver=0.3.1.r5.g4c9b436
+pkgver=0.4.0.r7.g77b94a5
 pkgrel=1
 pkgdesc="A greetd greeter for Wayland with GTK4 and Layer Shell"
 arch=('x86_64')

resources/resources.gresource.xml

@@ -1,7 +1,7 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <gresources>
   <gresource prefix="/dev/moonarch/moongreet">
-    <file>style.css</file>
-    <file>default-avatar.svg</file>
+    <file compressed="true">style.css</file>
+    <file compressed="true">default-avatar.svg</file>
   </gresource>
 </gresources>

resources/style.css

@@ -1,16 +1,16 @@
 /* ABOUTME: GTK4 CSS stylesheet for the Moongreet greeter. */
-/* ABOUTME: Defines styling for the login screen layout. */
+/* ABOUTME: Uses GTK theme colors for consistency with the active desktop theme. */
 
 /* Main window background */
 window.greeter {
-    background-color: #1a1a2e;
+    background-color: @theme_bg_color;
     background-size: cover;
     background-position: center;
 }
 
 /* Wallpaper-only window for secondary monitors */
 window.wallpaper {
-    background-color: #1a1a2e;
+    background-color: @theme_bg_color;
 }
 
 /* Central login area */
@@ -22,18 +22,18 @@ window.wallpaper {
 
 /* Round avatar image — size is set via set_size_request() in code */
 .avatar {
-    border-radius: 50%;
+    border-radius: 9999px;
     min-width: 128px;
     min-height: 128px;
     background-color: @theme_selected_bg_color;
-    border: 3px solid alpha(white, 0.3);
+    border: 3px solid alpha(@theme_fg_color, 0.3);
 }
 
 /* Username label */
 .username-label {
     font-size: 24px;
     font-weight: bold;
-    color: white;
+    color: @theme_fg_color;
     margin-top: 12px;
     margin-bottom: 40px;
 }
@@ -50,13 +50,13 @@ window.wallpaper {
 
 /* Error message label */
 .error-label {
-    color: #ff6b6b;
+    color: @error_color;
     font-size: 14px;
 }
 
 /* Fingerprint prompt label */
 .fingerprint-label {
-    color: alpha(white, 0.6);
+    color: alpha(@theme_fg_color, 0.6);
     font-size: 13px;
     margin-top: 8px;
 }
@@ -70,16 +70,16 @@ window.wallpaper {
 .user-list-item {
     padding: 8px 16px;
     border-radius: 8px;
-    color: white;
+    color: @theme_fg_color;
     font-size: 14px;
 }
 
 .user-list-item:hover {
-    background-color: alpha(white, 0.15);
+    background-color: alpha(@theme_fg_color, 0.15);
 }
 
 .user-list-item:selected {
-    background-color: alpha(white, 0.2);
+    background-color: alpha(@theme_fg_color, 0.2);
 }
 
 /* Power buttons on the bottom right */
@@ -88,12 +88,12 @@ window.wallpaper {
     min-height: 48px;
     padding: 0px;
     border-radius: 24px;
-    background-color: alpha(white, 0.1);
-    color: white;
+    background-color: alpha(@theme_fg_color, 0.1);
+    color: @theme_fg_color;
     border: none;
     margin: 4px;
 }
 
 .power-button:hover {
-    background-color: alpha(white, 0.25);
+    background-color: alpha(@theme_fg_color, 0.25);
 }

src/config.rs

@@ -72,8 +72,12 @@ pub fn load_config(config_paths: Option<&[PathBuf]>) -> Config {
                                         Some(parent.join(&bg).to_string_lossy().to_string());
                                 }
                             }
-                            if appearance.background_blur.is_some() {
-                                merged.background_blur = appearance.background_blur;
+                            if let Some(blur) = appearance.background_blur {
+                                if blur.is_finite() {
+                                    merged.background_blur = Some(blur.clamp(0.0, 200.0));
+                                } else {
+                                    log::warn!("Ignoring non-finite background-blur value");
+                                }
                             }
                             if appearance.gtk_theme.is_some() {
                                 merged.gtk_theme = appearance.gtk_theme;
@@ -107,14 +111,16 @@ pub fn resolve_background_path(config: &Config) -> Option<PathBuf> {
 
 /// Resolve with configurable moonarch wallpaper path (for testing).
 pub fn resolve_background_path_with(config: &Config, moonarch_wallpaper: &Path) -> Option<PathBuf> {
-    // User-configured path
+    // User-configured path — reject symlinks to prevent path traversal
     if let Some(ref bg) = config.background_path {
         let path = PathBuf::from(bg);
-        if path.is_file() {
+        if let Ok(meta) = path.symlink_metadata() {
+            if meta.is_file() && !meta.file_type().is_symlink() {
                 log::debug!("Wallpaper: using config path {}", path.display());
                 return Some(path);
             }
-        log::debug!("Wallpaper: config path {} not found, trying fallbacks", path.display());
+        }
+        log::debug!("Wallpaper: config path {} not usable, trying fallbacks", path.display());
     }
 
     // Moonarch ecosystem default
@@ -283,4 +289,45 @@ mod tests {
         let config = load_config(Some(&paths));
         assert!(!config.fingerprint_enabled);
     }
+
+    // -- Blur validation tests --
+
+    #[test]
+    fn load_config_blur_clamped_to_max() {
+        let dir = tempfile::tempdir().unwrap();
+        let conf = dir.path().join("moongreet.toml");
+        fs::write(&conf, "[appearance]\nbackground-blur = 999.0\n").unwrap();
+        let config = load_config(Some(&[conf]));
+        assert_eq!(config.background_blur, Some(200.0));
+    }
+
+    #[test]
+    fn load_config_blur_negative_clamped_to_zero() {
+        let dir = tempfile::tempdir().unwrap();
+        let conf = dir.path().join("moongreet.toml");
+        fs::write(&conf, "[appearance]\nbackground-blur = -5.0\n").unwrap();
+        let config = load_config(Some(&[conf]));
+        assert_eq!(config.background_blur, Some(0.0));
+    }
+
+    #[test]
+    fn load_config_blur_nan_rejected() {
+        let dir = tempfile::tempdir().unwrap();
+        let conf = dir.path().join("moongreet.toml");
+        // TOML doesn't support NaN literals, but the parser may return NaN for nan
+        fs::write(&conf, "[appearance]\nbackground-blur = nan\n").unwrap();
+        let config = load_config(Some(&[conf]));
+        // nan is not valid TOML float, so the whole config parse fails → no blur
+        assert!(config.background_blur.is_none());
+    }
+
+    #[test]
+    fn load_config_blur_inf_rejected() {
+        let dir = tempfile::tempdir().unwrap();
+        let conf = dir.path().join("moongreet.toml");
+        fs::write(&conf, "[appearance]\nbackground-blur = inf\n").unwrap();
+        let config = load_config(Some(&[conf]));
+        // inf is valid TOML → parsed as f32::INFINITY → rejected by is_finite() guard
+        assert!(config.background_blur.is_none());
+    }
 }

src/fingerprint.rs

@@ -10,6 +10,7 @@ const FPRINTD_MANAGER_IFACE: &str = "net.reactivated.Fprint.Manager";
 const FPRINTD_DEVICE_IFACE: &str = "net.reactivated.Fprint.Device";
 
 const DBUS_TIMEOUT_MS: i32 = 3000;
+const FPRINTD_DEVICE_PREFIX: &str = "/net/reactivated/Fprint/Device/";
 
 /// Lightweight fprintd probe — detects device availability and finger enrollment.
 /// Does NOT perform verification (that happens through greetd/PAM).
@@ -66,6 +67,10 @@ impl FingerprintProbe {
         if device_path.is_empty() {
             return;
         }
+        if !device_path.starts_with(FPRINTD_DEVICE_PREFIX) {
+            log::warn!("Unexpected fprintd device path: {device_path}");
+            return;
+        }
 
         match gio::DBusProxy::for_bus_future(
             gio::BusType::System,

src/greeter.rs

@@ -12,6 +12,7 @@ use std::os::unix::net::UnixStream;
 use std::path::{Path, PathBuf};
 use std::rc::Rc;
 use std::sync::{Arc, Mutex};
+use zeroize::Zeroizing;
 
 use crate::config::Config;
 use crate::i18n::{faillock_warning, load_strings, Strings};
@@ -87,7 +88,9 @@ fn is_valid_username(name: &str) -> bool {
     if name.is_empty() || name.len() > MAX_USERNAME_LENGTH {
         return false;
     }
-    let first = name.chars().next().unwrap();
+    let Some(first) = name.chars().next() else {
+        return false;
+    };
     if !first.is_ascii_alphanumeric() && first != '_' {
         return false;
     }
@@ -95,17 +98,29 @@ fn is_valid_username(name: &str) -> bool {
         .all(|c| c.is_ascii_alphanumeric() || c == '_' || c == '.' || c == '-' || c == '@')
 }
 
+/// Validate a GTK theme name — alphanumeric plus `_-+.` only.
+fn is_valid_gtk_theme(name: &str) -> bool {
+    !name.is_empty()
+        && name
+            .chars()
+            .all(|c| c.is_ascii_alphanumeric() || matches!(c, '_' | '-' | '+' | '.'))
+}
+
 /// Load background texture from filesystem.
 pub fn load_background_texture(bg_path: &Path) -> Option<gdk::Texture> {
-    if let Ok(meta) = std::fs::metadata(bg_path)
-        && meta.len() > MAX_WALLPAPER_FILE_SIZE
-    {
+    if let Ok(meta) = std::fs::symlink_metadata(bg_path) {
+        if meta.file_type().is_symlink() {
+            log::warn!("Rejecting symlink wallpaper: {}", bg_path.display());
+            return None;
+        }
+        if meta.len() > MAX_WALLPAPER_FILE_SIZE {
             log::warn!(
                 "Wallpaper file too large ({} bytes), skipping: {}",
                 meta.len(), bg_path.display()
             );
             return None;
         }
+    }
     match gdk::Texture::from_filename(bg_path) {
         Ok(texture) => Some(texture),
         Err(e) => {
@@ -118,11 +133,22 @@ pub fn load_background_texture(bg_path: &Path) -> Option<gdk::Texture> {
 
 // -- GPU blur via GskBlurNode -------------------------------------------------
 
+// SYNC: MAX_BLUR_DIMENSION, render_blurred_texture, and create_background_picture
+// are duplicated in moonlock/src/lockscreen.rs and moonset/src/panel.rs.
+// Changes here must be mirrored to the other two projects.
+
+/// Maximum texture dimension before downscaling for blur.
+/// Keeps GPU work reasonable on 4K+ displays.
+const MAX_BLUR_DIMENSION: f32 = 1920.0;
+
 /// Render a blurred texture using the GPU via GskBlurNode.
 ///
 /// To avoid edge darkening (blur samples transparent pixels outside bounds),
 /// the texture is rendered with padding equal to 3x the blur sigma. The blur
 /// is applied to the padded area, then cropped back to the original size.
+///
+/// Large textures (> MAX_BLUR_DIMENSION) are downscaled before blurring to
+/// reduce GPU work. The sigma is scaled proportionally.
 fn render_blurred_texture(
     widget: &impl IsA<gtk::Widget>,
     texture: &gdk::Texture,
@@ -131,17 +157,29 @@ fn render_blurred_texture(
     let native = widget.native()?;
     let renderer = native.renderer()?;
 
-    let w = texture.width() as f32;
-    let h = texture.height() as f32;
+    let orig_w = texture.width() as f32;
+    let orig_h = texture.height() as f32;
+
+    // Downscale large textures to reduce GPU blur work
+    let max_dim = orig_w.max(orig_h);
+    let scale = if max_dim > MAX_BLUR_DIMENSION {
+        MAX_BLUR_DIMENSION / max_dim
+    } else {
+        1.0
+    };
+    let w = (orig_w * scale).round();
+    let h = (orig_h * scale).round();
+    let scaled_sigma = sigma * scale;
+
     // Padding must cover the blur kernel radius (typically ~3x sigma)
-    let pad = (sigma * 3.0).ceil();
+    let pad = (scaled_sigma * 3.0).ceil();
 
     let snapshot = gtk::Snapshot::new();
-    // Clip output to original texture size
+    // Clip output to scaled texture size
     snapshot.push_clip(&graphene_rs::Rect::new(pad, pad, w, h));
-    snapshot.push_blur(sigma as f64);
+    snapshot.push_blur(scaled_sigma as f64);
     // Render texture with padding on all sides (edges repeat via oversized bounds)
-    snapshot.append_texture(texture, &graphene_rs::Rect::new(0.0, 0.0, w + 2.0 * pad, h + 2.0 * pad));
+    snapshot.append_texture(texture, &graphene_rs::Rect::new(-pad, -pad, w + 2.0 * pad, h + 2.0 * pad));
     snapshot.pop(); // blur
     snapshot.pop(); // clip
 
@@ -150,25 +188,13 @@ fn render_blurred_texture(
     Some(renderer.render_texture(&node, Some(&viewport)))
 }
 
-/// Create a wallpaper-only window for secondary monitors.
-pub fn create_wallpaper_window(
+/// 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.
+fn create_background_picture(
     texture: &gdk::Texture,
     blur_radius: Option<f32>,
-    app: &gtk::Application,
-) -> gtk::ApplicationWindow {
-    let window = gtk::ApplicationWindow::builder()
-        .application(app)
-        .build();
-    window.add_css_class("wallpaper");
-
-    let background = create_background_picture(texture, blur_radius);
-    window.set_child(Some(&background));
-
-    window
-}
-
-/// Create a Picture widget for the wallpaper background, optionally with GPU blur.
-fn create_background_picture(texture: &gdk::Texture, blur_radius: Option<f32>) -> gtk::Picture {
+    blur_cache: &Rc<RefCell<Option<gdk::Texture>>>,
+) -> gtk::Picture {
     let background = gtk::Picture::for_paintable(texture);
     background.set_content_fit(gtk::ContentFit::Cover);
     background.set_hexpand(true);
@@ -176,9 +202,16 @@ fn create_background_picture(texture: &gdk::Texture, blur_radius: Option<f32>) -
 
     if let Some(sigma) = blur_radius.filter(|s| *s > 0.0) {
         let texture = texture.clone();
+        let blur_cache = blur_cache.clone();
         background.connect_realize(move |picture| {
+            // Use cached blurred texture if available
+            if let Some(ref cached) = *blur_cache.borrow() {
+                picture.set_paintable(Some(cached));
+                return;
+            }
             if let Some(blurred) = render_blurred_texture(picture, &texture, sigma) {
                 picture.set_paintable(Some(&blurred));
+                *blur_cache.borrow_mut() = Some(blurred);
             }
         });
     }
@@ -193,14 +226,20 @@ struct GreeterState {
     default_avatar_texture: Option<gdk::Texture>,
     failed_attempts: HashMap<String, u32>,
     greetd_sock: Arc<Mutex<Option<UnixStream>>>,
+    greetd_sock_path: Option<String>,
     login_cancelled: Arc<std::sync::atomic::AtomicBool>,
     fingerprint_available: bool,
+    /// Incremented on each user switch to discard stale async results.
+    user_switch_generation: u64,
+    /// Cached fprintd device proxy — initialized once on first use.
+    fingerprint_probe: Option<crate::fingerprint::FingerprintProbe>,
 }
 
 /// Create the main greeter window with login UI.
 pub fn create_greeter_window(
     texture: Option<&gdk::Texture>,
     config: &Config,
+    blur_cache: &Rc<RefCell<Option<gdk::Texture>>>,
     app: &gtk::Application,
 ) -> gtk::ApplicationWindow {
     let window = gtk::ApplicationWindow::builder()
@@ -211,11 +250,7 @@ pub fn create_greeter_window(
 
     // Apply GTK theme from config
     if let Some(ref theme_name) = config.gtk_theme {
-        if !theme_name.is_empty()
-            && theme_name
-                .chars()
-                .all(|c| c.is_ascii_alphanumeric() || matches!(c, '_' | '-' | '+' | '.'))
-        {
+        if is_valid_gtk_theme(theme_name) {
             if let Some(settings) = gtk::Settings::default() {
                 settings.set_gtk_theme_name(Some(theme_name));
             }
@@ -233,14 +268,20 @@ pub fn create_greeter_window(
         log::debug!("GTK theme: {theme}");
     }
 
+    // Cache GREETD_SOCK at startup — it never changes during runtime
+    let greetd_sock_path = std::env::var("GREETD_SOCK").ok().filter(|p| !p.is_empty());
+
     let state = Rc::new(RefCell::new(GreeterState {
         selected_user: None,
         avatar_cache: HashMap::new(),
         default_avatar_texture: None,
         failed_attempts: HashMap::new(),
         greetd_sock: Arc::new(Mutex::new(None)),
+        greetd_sock_path,
         login_cancelled: Arc::new(std::sync::atomic::AtomicBool::new(false)),
         fingerprint_available: false,
+        user_switch_generation: 0,
+        fingerprint_probe: None,
     }));
 
     // Root overlay for layering
@@ -249,7 +290,7 @@ pub fn create_greeter_window(
 
     // Background wallpaper
     if let Some(texture) = texture {
-        overlay.set_child(Some(&create_background_picture(texture, config.background_blur)));
+        overlay.set_child(Some(&create_background_picture(texture, config.background_blur, blur_cache)));
     }
 
     // Main layout: 3 rows (top spacer, center login, bottom bar)
@@ -451,7 +492,7 @@ pub fn create_greeter_window(
             };
             let Some(user) = user else { return };
 
-            let password = entry.text().to_string();
+            let password = Zeroizing::new(entry.text().to_string());
 
             let session = get_selected_session(&session_dropdown, &sessions_rc);
             let Some(session) = session else {
@@ -494,6 +535,18 @@ pub fn create_greeter_window(
     ));
     window.add_controller(key_controller);
 
+    // Grab keyboard focus after map — layer-shell keyboard grab is only
+    // confirmed by the compositor at map time, not at realize time.
+    window.connect_map(clone!(
+        #[weak]
+        password_entry,
+        move |_| {
+            glib::idle_add_local_once(move || {
+                password_entry.grab_focus();
+            });
+        }
+    ));
+
     // Defer initial user selection until realized (for correct theme colors)
     window.connect_realize(clone!(
         #[strong]
@@ -559,6 +612,7 @@ pub fn create_greeter_window(
 }
 
 /// Select the last user or the first available user.
+#[allow(clippy::too_many_arguments)]
 fn select_initial_user(
     users: &[User],
     state: &Rc<RefCell<GreeterState>>,
@@ -601,6 +655,7 @@ fn select_initial_user(
 }
 
 /// Update the UI to show the selected user.
+#[allow(clippy::too_many_arguments)]
 fn switch_to_user(
     user: &User,
     state: &Rc<RefCell<GreeterState>>,
@@ -616,11 +671,13 @@ fn switch_to_user(
     strings: &'static Strings,
 ) {
     log::debug!("Switching to user: {}", user.username);
-    {
+    let generation = {
         let mut s = state.borrow_mut();
         s.selected_user = Some(user.clone());
         s.fingerprint_available = false;
-    }
+        s.user_switch_generation += 1;
+        s.user_switch_generation
+    };
 
     username_label.set_text(user.display_name());
     password_entry.set_text("");
@@ -650,7 +707,7 @@ fn switch_to_user(
     // Pre-select last used session for this user
     select_last_session(&user.username, session_dropdown, sessions);
 
-    // Probe fprintd for fingerprint availability
+    // Probe fprintd for fingerprint availability (cached device proxy, generation-guarded)
     if fingerprint_enabled {
         let username = user.username.clone();
         glib::spawn_future_local(clone!(
@@ -659,9 +716,29 @@ fn switch_to_user(
             #[strong]
             state,
             async move {
+                // Initialize probe on first use, then reuse cached device proxy
+                let needs_init = state.borrow().fingerprint_probe.is_none();
+                if needs_init {
                     let mut probe = crate::fingerprint::FingerprintProbe::new();
                     probe.init_async().await;
-                let available = probe.is_available_async(&username).await;
+                    state.borrow_mut().fingerprint_probe = Some(probe);
+                }
+
+                // Take probe out of state to avoid holding borrow across await
+                let probe = state.borrow_mut().fingerprint_probe.take();
+                let available = match &probe {
+                    Some(p) => p.is_available_async(&username).await,
+                    None => false,
+                };
+                state.borrow_mut().fingerprint_probe = probe;
+
+                // Discard result if user switched while we were probing
+                let s = state.borrow();
+                if s.user_switch_generation != generation {
+                    return;
+                }
+                drop(s);
+
                 state.borrow_mut().fingerprint_available = available;
                 fp_label.set_visible(available);
                 if available {
@@ -834,15 +911,19 @@ fn extract_greetd_description<'a>(response: &'a serde_json::Value, fallback: &'a
         .unwrap_or(fallback)
 }
 
-/// Display a greetd error, using a fallback for missing or oversized descriptions.
+/// Display a greetd error. Logs raw PAM details at debug level,
+/// shows only the generic fallback in the UI to avoid leaking system info.
 fn show_greetd_error(
     error_label: &gtk::Label,
     password_entry: &gtk::PasswordEntry,
     response: &serde_json::Value,
     fallback: &str,
 ) {
-    let message = extract_greetd_description(response, fallback);
-    show_error(error_label, password_entry, message);
+    let raw = extract_greetd_description(response, fallback);
+    if raw != fallback {
+        log::debug!("greetd error detail: {raw}");
+    }
+    show_error(error_label, password_entry, fallback);
 }
 
 /// Cancel any in-progress greetd session.
@@ -851,11 +932,11 @@ fn cancel_pending_session(state: &Rc<RefCell<GreeterState>>) {
     let s = state.borrow();
     s.login_cancelled
         .store(true, std::sync::atomic::Ordering::SeqCst);
-    if let Ok(mut sock_guard) = s.greetd_sock.lock() {
-        if let Some(sock) = sock_guard.take() {
+    if let Ok(mut sock_guard) = s.greetd_sock.lock()
+        && let Some(sock) = sock_guard.take()
+    {
         let _ = sock.shutdown(std::net::Shutdown::Both);
     }
-    }
 }
 
 /// Set login controls sensitivity.
@@ -882,9 +963,9 @@ fn attempt_login(
     session_dropdown: &gtk::DropDown,
 ) {
     log::debug!("Login attempt for user: {}", user.username);
-    let sock_path = match std::env::var("GREETD_SOCK") {
-        Ok(p) if !p.is_empty() => p,
-        _ => {
+    let sock_path = match state.borrow().greetd_sock_path.clone() {
+        Some(p) => p,
+        None => {
             show_error(error_label, password_entry, strings.greetd_sock_not_set);
             return;
         }
@@ -902,28 +983,6 @@ fn attempt_login(
         return;
     }
 
-    match std::fs::metadata(&sock_pathbuf) {
-        Ok(meta) => {
-            use std::os::unix::fs::FileTypeExt;
-            if !meta.file_type().is_socket() {
-                show_error(
-                    error_label,
-                    password_entry,
-                    strings.greetd_sock_not_socket,
-                );
-                return;
-            }
-        }
-        Err(_) => {
-            show_error(
-                error_label,
-                password_entry,
-                strings.greetd_sock_unreachable,
-            );
-            return;
-        }
-    }
-
     // Reset cancellation flag and disable UI
     {
         let s = state.borrow();
@@ -933,7 +992,7 @@ fn attempt_login(
     set_login_sensitive(password_entry, session_dropdown, false);
 
     let username = user.username.clone();
-    let password = password.to_string();
+    let password = Zeroizing::new(password.to_string());
     let exec_cmd = session.exec_cmd.clone();
     let session_name = session.name.clone();
     let greetd_sock = state.borrow().greetd_sock.clone();
@@ -953,6 +1012,8 @@ fn attempt_login(
         state,
         async move {
             let session_name_clone = session_name.clone();
+            // Minimum response time to prevent username enumeration via timing
+            let login_start = std::time::Instant::now();
             let result = gio::spawn_blocking(move || {
                 login_worker(
                     &username,
@@ -966,6 +1027,11 @@ fn attempt_login(
                 )
             })
             .await;
+            let elapsed = login_start.elapsed();
+            let min_response = std::time::Duration::from_millis(500);
+            if elapsed < min_response {
+                glib::timeout_future(min_response - elapsed).await;
+            }
 
             match result {
                 Ok(Ok(LoginResult::Success { username })) => {
@@ -1030,6 +1096,7 @@ enum LoginResult {
 }
 
 /// Run greetd IPC in a background thread.
+#[allow(clippy::too_many_arguments)]
 fn login_worker(
     username: &str,
     password: &str,
@@ -1076,8 +1143,11 @@ fn login_worker(
             return Ok(LoginResult::Cancelled);
         }
         if response.get("type").and_then(|v| v.as_str()) == Some("error") {
-            let message = extract_greetd_description(&response, strings.auth_failed).to_string();
-            return Ok(LoginResult::Error { message });
+            let raw = extract_greetd_description(&response, strings.auth_failed);
+            if raw != strings.auth_failed {
+                log::debug!("greetd error detail: {raw}");
+            }
+            return Ok(LoginResult::Error { message: strings.auth_failed.to_string() });
         }
     }
 
@@ -1165,9 +1235,12 @@ fn login_worker(
                 username: username.to_string(),
             });
         } else {
+            let raw = extract_greetd_description(&response, strings.session_start_failed);
+            if raw != strings.session_start_failed {
+                log::debug!("greetd error detail: {raw}");
+            }
             return Ok(LoginResult::Error {
-                message: extract_greetd_description(&response, strings.session_start_failed)
-                    .to_string(),
+                message: strings.session_start_failed.to_string(),
             });
         }
     }
@@ -1190,7 +1263,7 @@ fn execute_power_action(
         #[weak]
         button,
         async move {
-            let result = gio::spawn_blocking(move || action_fn()).await;
+            let result = gio::spawn_blocking(action_fn).await;
 
             match result {
                 Ok(Ok(())) => {}
@@ -1213,6 +1286,15 @@ fn execute_power_action(
 
 // -- Last user/session persistence --
 
+/// Create a cache directory with restricted permissions (0o700).
+fn create_cache_dir(path: &Path) -> std::io::Result<()> {
+    use std::os::unix::fs::DirBuilderExt;
+    std::fs::DirBuilder::new()
+        .recursive(true)
+        .mode(0o700)
+        .create(path)
+}
+
 fn load_last_user() -> Option<String> {
     load_last_user_from(Path::new(LAST_USER_PATH))
 }
@@ -1236,7 +1318,7 @@ fn save_last_user(username: &str) {
 fn save_last_user_to(path: &Path, username: &str) {
     log::debug!("Saving last user: {username}");
     if let Some(parent) = path.parent()
-        && let Err(e) = std::fs::create_dir_all(parent)
+        && let Err(e) = create_cache_dir(parent)
     {
         log::warn!("Failed to create cache dir {}: {e}", parent.display());
         return;
@@ -1289,7 +1371,10 @@ fn save_last_session(username: &str, session_name: &str) {
         return;
     }
     let dir = Path::new(LAST_SESSION_DIR);
-    let _ = std::fs::create_dir_all(dir);
+    if let Err(e) = create_cache_dir(dir) {
+        log::warn!("Failed to create session cache dir {}: {e}", dir.display());
+        return;
+    }
     save_last_session_to(&dir.join(username), session_name);
 }
 
@@ -1884,4 +1969,55 @@ mod tests {
         let resp = serde_json::json!({"type": "error"});
         assert_eq!(extract_greetd_description(&resp, "fallback"), "fallback");
     }
+
+    // -- GTK theme validation --
+
+    #[test]
+    fn valid_gtk_themes() {
+        assert!(is_valid_gtk_theme("Adwaita"));
+        assert!(is_valid_gtk_theme("Catppuccin-Mocha"));
+        assert!(is_valid_gtk_theme("Arc_Dark"));
+        assert!(is_valid_gtk_theme("Theme+Variant"));
+        assert!(is_valid_gtk_theme("v1.0"));
+    }
+
+    #[test]
+    fn invalid_gtk_themes() {
+        assert!(!is_valid_gtk_theme(""));
+        assert!(!is_valid_gtk_theme("../evil"));
+        assert!(!is_valid_gtk_theme("theme/path"));
+        assert!(!is_valid_gtk_theme("theme name"));
+        assert!(!is_valid_gtk_theme("thème"));
+        assert!(!is_valid_gtk_theme("theme\0null"));
+    }
+
+    // -- Username validation: Unicode edge cases --
+
+    #[test]
+    fn invalid_unicode_usernames() {
+        assert!(!is_valid_username("üser"));
+        assert!(!is_valid_username("用户"));
+        assert!(!is_valid_username("user🔑"));
+    }
+
+    // -- Cache directory permissions --
+
+    #[test]
+    fn create_cache_dir_sets_mode_0o700() {
+        let tmp = tempfile::tempdir().unwrap();
+        let cache_dir = tmp.path().join("cache");
+        create_cache_dir(&cache_dir).unwrap();
+
+        use std::os::unix::fs::PermissionsExt;
+        let mode = std::fs::metadata(&cache_dir).unwrap().permissions().mode() & 0o777;
+        assert_eq!(mode, 0o700, "Cache dir should be 0o700, got {mode:#o}");
+    }
+
+    #[test]
+    fn save_last_session_with_unwritable_dir() {
+        // Attempt to save in a non-existent dir under /proc (guaranteed unwritable)
+        let path = Path::new("/proc/nonexistent-moongreet-test/session");
+        save_last_session_to(path, "niri");
+        // Should not panic — just logs a warning
+    }
 }

src/i18n.rs

@@ -4,6 +4,7 @@
 use std::env;
 use std::fs;
 use std::path::Path;
+use std::sync::OnceLock;
 
 const DEFAULT_LOCALE_CONF: &str = "/etc/locale.conf";
 
@@ -19,8 +20,6 @@ pub struct Strings {
     pub no_session_selected: &'static str,
     pub greetd_sock_not_set: &'static str,
     pub greetd_sock_not_absolute: &'static str,
-    pub greetd_sock_not_socket: &'static str,
-    pub greetd_sock_unreachable: &'static str,
     pub auth_failed: &'static str,
     pub wrong_password: &'static str,
     pub fingerprint_prompt: &'static str,
@@ -43,8 +42,6 @@ const STRINGS_DE: Strings = Strings {
     no_session_selected: "Keine Session ausgewählt",
     greetd_sock_not_set: "GREETD_SOCK nicht gesetzt",
     greetd_sock_not_absolute: "GREETD_SOCK ist kein absoluter Pfad",
-    greetd_sock_not_socket: "GREETD_SOCK zeigt nicht auf einen Socket",
-    greetd_sock_unreachable: "GREETD_SOCK nicht erreichbar",
     auth_failed: "Authentifizierung fehlgeschlagen",
     wrong_password: "Falsches Passwort",
     fingerprint_prompt: "Fingerabdruck auflegen oder Passwort eingeben",
@@ -65,8 +62,6 @@ const STRINGS_EN: Strings = Strings {
     no_session_selected: "No session selected",
     greetd_sock_not_set: "GREETD_SOCK not set",
     greetd_sock_not_absolute: "GREETD_SOCK is not an absolute path",
-    greetd_sock_not_socket: "GREETD_SOCK does not point to a socket",
-    greetd_sock_unreachable: "GREETD_SOCK unreachable",
     auth_failed: "Authentication failed",
     wrong_password: "Wrong password",
     fingerprint_prompt: "Place finger on reader or enter password",
@@ -135,14 +130,17 @@ pub fn detect_locale() -> String {
     result
 }
 
+/// Cached locale — detected once, reused for the lifetime of the process.
+static CACHED_LOCALE: OnceLock<String> = OnceLock::new();
+
 /// Return the string table for the given locale, defaulting to English.
 pub fn load_strings(locale: Option<&str>) -> &'static Strings {
     let locale = match locale {
-        Some(l) => l.to_string(),
-        None => detect_locale(),
+        Some(l) => l,
+        None => CACHED_LOCALE.get_or_init(detect_locale),
     };
 
-    match locale.as_str() {
+    match locale {
         "de" => &STRINGS_DE,
         _ => &STRINGS_EN,
     }

src/main.rs

@@ -11,16 +11,18 @@ 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");
     gtk::style_context_add_provider_for_display(
         display,
         &css_provider,
-        gtk::STYLE_PROVIDER_PRIORITY_APPLICATION,
+        gtk::STYLE_PROVIDER_PRIORITY_USER,
     );
 }
 
@@ -58,33 +60,59 @@ fn activate(app: &gtk::Application) {
             greeter::load_background_texture(&path)
         });
 
+    let blur_cache = std::rc::Rc::new(std::cell::RefCell::new(None));
+
     let use_layer_shell = std::env::var("MOONGREET_NO_LAYER_SHELL").is_err();
     log::debug!("Layer shell: {use_layer_shell}");
 
-    // Main greeter window (login UI) — compositor picks focused monitor
-    let greeter_window = greeter::create_greeter_window(bg_texture.as_ref(), &config, app);
     if use_layer_shell {
-        setup_layer_shell(&greeter_window, true, gtk4_layer_shell::Layer::Top);
-    }
-    greeter_window.present();
-
-    // Wallpaper-only windows on all monitors (only with layer shell)
-    if use_layer_shell
-        && let Some(ref texture) = bg_texture
-    {
+        // 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())
             {
-                let wallpaper = greeter::create_wallpaper_window(texture, config.background_blur, app);
-                setup_layer_shell(&wallpaper, false, gtk4_layer_shell::Layer::Bottom);
-                wallpaper.set_monitor(Some(&monitor));
-                wallpaper.present();
+                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));
+                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);
+        greeter_window.present();
     }
 }
 

src/power.rs

@@ -2,11 +2,18 @@
 // ABOUTME: Wrappers around system commands for the greeter UI.
 
 use std::fmt;
-use std::process::Command;
+use std::io::Read;
+use std::process::{Command, Stdio};
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::Arc;
+use std::time::Duration;
+
+const POWER_TIMEOUT: Duration = Duration::from_secs(30);
 
 #[derive(Debug)]
 pub enum PowerError {
     CommandFailed { action: &'static str, message: String },
+    Timeout { action: &'static str },
 }
 
 impl fmt::Display for PowerError {
@@ -15,41 +22,79 @@ impl fmt::Display for PowerError {
             PowerError::CommandFailed { action, message } => {
                 write!(f, "{action} failed: {message}")
             }
+            PowerError::Timeout { action } => {
+                write!(f, "{action} timed out")
+            }
         }
     }
 }
 
 impl std::error::Error for PowerError {}
 
-/// Run a command and return a PowerError on failure.
+/// Run a command with timeout and return a PowerError on failure.
+///
+/// Uses blocking `child.wait()` with a separate timeout thread that sends
+/// SIGKILL after POWER_TIMEOUT. This runs inside `gio::spawn_blocking`,
+/// so blocking is expected.
 fn run_command(action: &'static str, program: &str, args: &[&str]) -> Result<(), PowerError> {
     log::debug!("Power action: {action} ({program} {args:?})");
-    let child = Command::new(program)
+    let mut child = Command::new(program)
         .args(args)
+        .stdout(Stdio::piped())
+        .stderr(Stdio::piped())
         .spawn()
         .map_err(|e| PowerError::CommandFailed {
             action,
             message: e.to_string(),
         })?;
 
-    let output = child
-        .wait_with_output()
-        .map_err(|e| PowerError::CommandFailed {
+    let child_pid = nix::unistd::Pid::from_raw(child.id() as i32);
+    let done = Arc::new(AtomicBool::new(false));
+    let done_clone = done.clone();
+
+    let timeout_thread = std::thread::spawn(move || {
+        let interval = Duration::from_millis(100);
+        let mut elapsed = Duration::ZERO;
+        while elapsed < POWER_TIMEOUT {
+            std::thread::sleep(interval);
+            if done_clone.load(Ordering::Relaxed) {
+                return;
+            }
+            elapsed += interval;
+        }
+        // ESRCH if the process already exited — harmless
+        let _ = nix::sys::signal::kill(child_pid, nix::sys::signal::Signal::SIGKILL);
+    });
+
+    let status = child.wait().map_err(|e| PowerError::CommandFailed {
         action,
         message: e.to_string(),
     })?;
 
-    if output.status.success() {
-        log::debug!("Power action {action} completed successfully");
+    done.store(true, Ordering::Relaxed);
+    let _ = timeout_thread.join();
+
+    if status.success() {
+        log::debug!("Power action {action} completed");
+        Ok(())
     } else {
-        let stderr = String::from_utf8_lossy(&output.stderr);
-        return Err(PowerError::CommandFailed {
-            action,
-            message: format!("exit code {}: {}", output.status, stderr.trim()),
-        });
+        #[cfg(unix)]
+        {
+            use std::os::unix::process::ExitStatusExt;
+            if status.signal() == Some(9) {
+                return Err(PowerError::Timeout { action });
+            }
         }
 
-    Ok(())
+        let mut stderr_buf = String::new();
+        if let Some(mut stderr) = child.stderr.take() {
+            let _ = stderr.read_to_string(&mut stderr_buf);
+        }
+        Err(PowerError::CommandFailed {
+            action,
+            message: format!("exit code {}: {}", status, stderr_buf.trim()),
+        })
+    }
 }
 
 /// Reboot the system via loginctl.
@@ -75,6 +120,12 @@ mod tests {
         assert_eq!(err.to_string(), "reboot failed: No such file or directory");
     }
 
+    #[test]
+    fn power_error_timeout_display() {
+        let err = PowerError::Timeout { action: "shutdown" };
+        assert_eq!(err.to_string(), "shutdown timed out");
+    }
+
     #[test]
     fn run_command_returns_error_for_missing_binary() {
         let result = run_command("test", "nonexistent-binary-xyz", &[]);
@@ -99,7 +150,7 @@ mod tests {
 
     #[test]
     fn run_command_passes_args() {
-        let result = run_command("test", "true", &["--ignored-arg"]);
+        let result = run_command("test", "echo", &["hello", "world"]);
         assert!(result.is_ok());
     }
 }

src/sessions.rs

@@ -36,16 +36,16 @@ fn parse_desktop_file(path: &Path, session_type: &str) -> Option<Session> {
             continue;
         }
 
-        if let Some(value) = line.strip_prefix("Name=") {
-            if name.is_none() {
+        if let Some(value) = line.strip_prefix("Name=")
+            && name.is_none()
+        {
             name = Some(value.to_string());
-            }
-        } else if let Some(value) = line.strip_prefix("Exec=") {
-            if exec_cmd.is_none() {
+        } else if let Some(value) = line.strip_prefix("Exec=")
+            && exec_cmd.is_none()
+        {
             exec_cmd = Some(value.to_string());
         }
     }
-    }
 
     let name = name.filter(|s| !s.is_empty());
     let exec_cmd = exec_cmd.filter(|s| !s.is_empty());

src/users.rs

@@ -70,7 +70,7 @@ pub fn get_users(passwd_path: Option<&Path>) -> Vec<User> {
             Err(_) => continue,
         };
 
-        if uid < MIN_UID || uid > MAX_UID {
+        if !(MIN_UID..=MAX_UID).contains(&uid) {
             continue;
         }
         if NOLOGIN_SHELLS.contains(&shell) {
@@ -94,7 +94,7 @@ pub fn get_users(passwd_path: Option<&Path>) -> Vec<User> {
     users
 }
 
-/// Find avatar for a user: AccountsService icon > ~/.face > None.
+/// Find avatar for a user: ~/.face > AccountsService icon > None.
 /// Rejects symlinks to prevent path traversal.
 pub fn get_avatar_path(username: &str, home: &Path) -> Option<PathBuf> {
     get_avatar_path_with(username, home, Path::new(DEFAULT_ACCOUNTSSERVICE_DIR))
@@ -106,30 +106,30 @@ pub fn get_avatar_path_with(
     home: &Path,
     accountsservice_dir: &Path,
 ) -> Option<PathBuf> {
-    // AccountsService icon takes priority
+    // ~/.face takes priority (consistent with moonlock/moonset)
+    let face = home.join(".face");
+    if let Ok(meta) = face.symlink_metadata() {
+        if meta.file_type().is_symlink() {
+            log::warn!("Rejecting symlink avatar for {username}: {}", face.display());
+        } else if meta.is_file() {
+            log::debug!("Avatar for {username}: ~/.face {}", face.display());
+            return Some(face);
+        }
+    }
+
+    // AccountsService icon fallback
     if accountsservice_dir.exists() {
         let icon = accountsservice_dir.join(username);
         if let Ok(meta) = icon.symlink_metadata() {
             if meta.file_type().is_symlink() {
                 log::warn!("Rejecting symlink avatar for {username}: {}", icon.display());
-            } else {
+            } else if meta.is_file() {
                 log::debug!("Avatar for {username}: AccountsService {}", icon.display());
                 return Some(icon);
             }
         }
     }
 
-    // ~/.face fallback
-    let face = home.join(".face");
-    if let Ok(meta) = face.symlink_metadata() {
-        if meta.file_type().is_symlink() {
-            log::warn!("Rejecting symlink avatar for {username}: {}", face.display());
-        } else {
-            log::debug!("Avatar for {username}: ~/.face {}", face.display());
-            return Some(face);
-        }
-    }
-
     log::debug!("No avatar found for {username}");
     None
 }
@@ -248,7 +248,7 @@ mod tests {
     }
 
     #[test]
-    fn accountsservice_icon_takes_priority() {
+    fn face_file_takes_priority_over_accountsservice() {
         let dir = tempfile::tempdir().unwrap();
         let icons_dir = dir.path().join("icons");
         fs::create_dir(&icons_dir).unwrap();
@@ -261,7 +261,7 @@ mod tests {
         fs::write(&face, "fake face").unwrap();
 
         let path = get_avatar_path_with("testuser", &home, &icons_dir);
-        assert_eq!(path, Some(icon));
+        assert_eq!(path, Some(face));
     }
 
     #[test]