fix: audit fixes — RefCell across await, async avatar decode (v0.6.10)

- init_fingerprint_async: hoist username before the await so a concurrent
  connect_monitor signal (hotplug / suspend-resume) cannot cause a RefCell
  panic. Re-borrow after the await for signal wiring.
- set_avatar_from_file: decode via gio::File::read_future +
  Pixbuf::from_stream_at_scale_future so the GTK main thread stays
  responsive during monitor hotplug. Default icon shown while loading.

CLAUDE.md

@@ -1,7 +1,5 @@
 # Moonlock
 
-**Name**: Nyx (Göttin der Nacht — passend zum Lockscreen, der den Bildschirm verdunkelt)
-
 ## Projekt
 
 Moonlock ist ein sicherer Wayland-Lockscreen, gebaut mit Rust + gtk4-rs + ext-session-lock-v1.
@@ -44,7 +42,7 @@ LD_PRELOAD=/usr/lib/libgtk4-layer-shell.so ./target/release/moonlock
 - `i18n.rs` — Locale-Erkennung (OnceLock-cached) und String-Tabellen (DE/EN), faillock_warning mit konfigurierbarem max_attempts
 - `config.rs` — TOML-Config (background_path, background_blur clamped [0,100], fingerprint_enabled als Option<bool>) + Wallpaper-Fallback + Symlink-Rejection via symlink_metadata + Parse-Error-Logging
 - `lockscreen.rs` — GTK4 UI via LockscreenHandles, PAM-Auth via gio::spawn_blocking mit 30s Timeout und Generation Counter, FP-Label/Start separat verdrahtet mit pam_acct_mgmt-Check und auto-resume, Zeroizing<String> für Passwort, Power-Confirm, GPU-Blur via GskBlurNode (Downscale auf max 1920px), Blur/Avatar-Cache für Multi-Monitor
-- `main.rs` — Entry Point, Panic-Hook (vor Logging), Root-Check, ext-session-lock-v1 (Pflicht in Release), Multi-Monitor mit shared Blur/Avatar-Caches, systemd-Journal-Logging, Debug-Level per `MOONLOCK_DEBUG` Env-Var, async fprintd-Init nach window.present(), Wallpaper-Laden nach lock()
+- `main.rs` — Entry Point, Panic-Hook (vor Logging), Root-Check, ext-session-lock-v1 (Pflicht in Release), Monitor-Hotplug via `connect_monitor`-Signal (v1_2), shared Blur/Avatar-Caches in Rc, systemd-Journal-Logging, Debug-Level per `MOONLOCK_DEBUG` Env-Var, async fprintd-Init nach window.present()
 
 ## Sicherheit
 
@@ -55,7 +53,7 @@ LD_PRELOAD=/usr/lib/libgtk4-layer-shell.so ./target/release/moonlock
 - fprintd: D-Bus Signal-Sender wird gegen fprintd's unique bus name validiert (Anti-Spoofing)
 - Passwort: Zeroizing<String> ab GTK-Entry-Extraktion, Zeroizing<CString> im PAM-FFI-Layer (bekannte Einschränkung: GLib-GString und strdup-Kopie in PAM werden nicht gezeroized — inhärente GTK/libc-Limitierung)
 - Fingerprint-Unlock: pam_acct_mgmt-Check nach verify-match erzwingt Account-Policies (Lockout, Ablauf), resume_async() startet FP bei transientem Fehler neu (mit failed_attempts-Reset und Signal-Handler-Cleanup)
-- Wallpaper wird nach lock() geladen — Disk-I/O verzögert nicht die Lock-Akquisition
+- Wallpaper wird vor lock() geladen — connect_monitor feuert während lock() und braucht die Textur; lokales JPEG-Laden ist schnell genug
 - PAM-Timeout: 30s Timeout verhindert permanentes Aussperren bei hängenden PAM-Modulen, Generation Counter verhindert Interferenz paralleler Auth-Versuche
 - Root-Check: Exit mit Fehler wenn als root gestartet
 - Faillock: UI-Warnung nach 3 Fehlversuchen, aber PAM entscheidet über Lockout (Entry bleibt aktiv)

Cargo.lock

@@ -575,7 +575,7 @@ dependencies = [
 
 [[package]]
 name = "moonlock"
-version = "0.6.8"
+version = "0.6.9"
 dependencies = [
  "gdk-pixbuf",
  "gdk4",

Cargo.toml

@@ -1,13 +1,13 @@
 [package]
 name = "moonlock"
-version = "0.6.8"
+version = "0.6.10"
 edition = "2024"
 description = "A secure Wayland lockscreen with GTK4, PAM and fingerprint support"
 license = "MIT"
 
 [dependencies]
 gtk4 = { version = "0.11", features = ["v4_10"] }
-gtk4-session-lock = { version = "0.4", features = ["v1_1"] }
+gtk4-session-lock = { version = "0.4", features = ["v1_2"] }
 glib = "0.22"
 gdk4 = "0.11"
 gdk-pixbuf = "0.22"

DECISIONS.md

@@ -2,58 +2,72 @@
 
 Architectural and design decisions for Moonlock, in reverse chronological order.
 
+## 2026-04-24 – Audit fixes: RefCell borrow across await, async avatar decode
+
+- **Who**: ClaudeCode, Dom
+- **Why**: Triple audit found two HIGH issues. (1) `init_fingerprint_async` held a `RefCell` immutable borrow across `is_available_async().await` — a concurrent `connect_monitor` signal (hotplug / suspend-resume) invoking `borrow_mut()` during the await would panic. (2) `set_avatar_from_file` decoded avatars synchronously via `Pixbuf::from_file_at_scale`, blocking the GTK main thread inside the `connect_monitor` handler. With `MAX_AVATAR_FILE_SIZE` at 10 MB the worst-case stall was 200–500 ms on monitor hotplug.
+- **Tradeoffs**: Avatar is shown as the symbolic default icon for a brief window while decoding completes. Wallpaper stays synchronous because `connect_monitor` fires during `lock()` and needs the texture already present (see 2026-04-09).
+- **How**: (1) Extract `username` into a local `String` in `init_fingerprint_async`, drop the borrow before the await, re-borrow in a new scope after — no awaits inside the second borrow, so hotplug during signal setup is safe. (2) `set_avatar_from_file` now uses `gio::File::read_future` + `Pixbuf::from_stream_at_scale_future` for async I/O and decode. The default icon is shown immediately; the decoded texture replaces it when ready. `Pixbuf` itself is `!Send`, so `gio::spawn_blocking` does not apply — the GIO async stream loader keeps the `Pixbuf` on the main thread while the kernel does the I/O asynchronously.
+
+## 2026-04-09 – Monitor hotplug via connect_monitor signal
+
+- **Who**: ClaudeCode, Dom
+- **Why**: moonlock crashed with segfault in libgtk-4.so after suspend/resume — HDMI monitor disconnect/reconnect invalidated GDK monitor objects, and the statically created windows referenced destroyed surfaces. Crash at consistent GTK4 offset (0x278 NULL dereference), 3x reproduced.
+- **Tradeoffs**: Wallpaper texture now loaded before `lock()` instead of after (connect_monitor fires during lock() and needs the texture). Local JPEG loading is fast enough that the delay is negligible. Shared state moved to Rc's for the signal closure — slightly more indirection but necessary for dynamic window creation.
+- **How**: (1) Bump gtk4-session-lock feature from `v1_1` to `v1_2` to enable `Instance::connect_monitor`. (2) Replace manual monitor iteration with `lock.connect_monitor()` signal handler that creates windows on demand. (3) Signal fires once per existing monitor at `lock()` and again on hotplug. (4) Windows auto-unmap when their monitor disappears (ext-session-lock-v1 guarantee). (5) Fingerprint listener published to shared Rc so hotplugged monitors get FP labels.
+
 ## 2026-03-31 – Fourth audit: peek icon, blur limit, GResource compression, sync markers
 
-- **Who**: Ragnar, Dom
+- **Who**: ClaudeCode, Dom
 - **Why**: Fourth triple audit found blur limit inconsistency (moonlock 0–100 vs moongreet/moonset 0–200), missing GResource compression, peek icon inconsistency, and duplicated code without sync markers.
 - **Tradeoffs**: Peek icon enabled in lockscreen — user decision favoring UX consistency over shoulder-surfing protection. Acceptable for single-user desktop. Blur limit raised to 200 for ecosystem consistency.
 - **How**: (1) `show_peek_icon(true)` in lockscreen password entry. (2) `clamp(0.0, 200.0)` for blur in config.rs. (3) `compressed="true"` on CSS/SVG GResource entries. (4) SYNC comments on duplicated blur/background functions pointing to moongreet and moonset.
 
 ## 2026-03-30 – Third audit: blur offset, lock-before-IO, FP signal lifecycle, TOCTOU
 
-- **Who**: Nyx, Dom
+- **Who**: ClaudeCode, Dom
 - **Why**: Third triple audit (quality, performance, security) found: blur padding offset rendering texture at (0,0) instead of (-pad,-pad) causing edge darkening on left/top (BUG), wallpaper disk I/O blocking before lock() extending the unsecured window (PERF/SEC), signal handler duplication on resume_async (SEC), failed_attempts not reset on FP resume (SEC), unknown VerifyStatus with done=false hanging FP listener (SEC), TOCTOU in is_file+is_symlink checks (SEC), dead code in faillock_warning (QUALITY), unbounded blur sigma (SEC).
 - **Tradeoffs**: Wallpaper loads after lock() — screen briefly shows without wallpaper until texture is ready. Acceptable: security > aesthetics. Blur sigma clamped to [0.0, 100.0] — arbitrary upper bound but prevents GPU memory exhaustion.
 - **How**: (1) Texture offset to (-pad, -pad) in render_blurred_texture. (2) lock.lock() before resolve_background_path. (3) begin_verification disconnects old signal_id before registering new. (4) resume_async resets failed_attempts. (5) Unknown VerifyStatus with done=true triggers restart. (6) symlink_metadata() for atomic file+symlink check. (7) faillock_warning dead code removed, saturating_sub. (8) background_blur clamped. (9) Redundant Zeroizing<Vec<u8>> removed. (10) Default impl for FingerprintListener. (11) on_verify_status restricted to pub(crate). (12) Warn logging for non-UTF-8 GECOS and avatar paths.
 
 ## 2026-03-30 – Second audit: zeroize CString, FP account check, PAM timeout, blur downscale
 
-- **Who**: Nyx, Dom
+- **Who**: ClaudeCode, Dom
 - **Why**: Second triple audit (quality, performance, security) found: CString password copy not zeroized (HIGH), fingerprint unlock bypassing pam_acct_mgmt (MEDIUM), no PAM timeout leaving user locked out on hanging modules (MEDIUM), GPU blur on full wallpaper resolution (MEDIUM), no-monitor edge case doing `return` instead of `exit(1)` (MEDIUM).
 - **Tradeoffs**: PAM timeout (30s) uses a generation counter to avoid stale result interference — adds complexity but prevents parallel PAM sessions. FP restart after failed account check re-claims the device, adding a D-Bus round-trip, but prevents permanent FP death on transient failures. Blur downscale to 1920px cap trades negligible quality for ~4x less GPU work on 4K wallpapers.
 - **How**: (1) `Zeroizing<CString>` wraps password in auth.rs, `zeroize/std` feature enabled. (2) `check_account()` calls pam_acct_mgmt after FP match; `resume_async()` restarts FP on transient failure. (3) `auth_generation` counter invalidates stale PAM results; 30s timeout re-enables UI. (4) `MAX_BLUR_DIMENSION` caps blur input at 1920px, sigma scaled proportionally. (5) `exit(1)` on no-monitor after `lock.lock()`.
 
 ## 2026-03-28 – Remove embedded wallpaper from binary
 
-- **Who**: Nyx, Dom
+- **Who**: ClaudeCode, Dom
 - **Why**: Wallpaper is installed by moonarch to /usr/share/moonarch/wallpaper.jpg. Embedding a 374K JPEG in the binary is redundant. GTK background color (Catppuccin Mocha base) is a clean fallback.
 - **Tradeoffs**: Without moonarch installed AND without config, lockscreen shows plain dark background instead of wallpaper. Acceptable — that's the expected minimal state.
 - **How**: Remove wallpaper.jpg from GResources, return None from resolve_background_path when no file found, skip background picture creation when no texture available.
 
 ## 2026-03-28 – Audit-driven security and lifecycle fixes (v0.6.0)
 
-- **Who**: Nyx, Dom
+- **Who**: ClaudeCode, Dom
 - **Why**: Triple audit (quality, performance, security) revealed a critical D-Bus signal spoofing vector, fingerprint lifecycle bugs, and multi-monitor performance issues.
 - **Tradeoffs**: `cleanup_dbus()` extraction adds a method but clarifies the stop/match ownership; `running_flag: Rc<Cell<bool>>` adds a field but prevents race between async restart and stop; sender validation adds a check per signal but closes the only known auth bypass.
 - **How**: (1) Validate D-Bus VerifyStatus sender against fprintd's unique bus name. (2) Extract `cleanup_dbus()` from `stop()`, call it on verify-match. (3) `Rc<Cell<bool>>` running flag checked after await in `restart_verify_async`. (4) Consistent 3s D-Bus timeouts. (5) Panic hook before logging. (6) Blur and avatar caches shared across monitors. (7) Peek icon disabled. (8) Symlink rejection for background_path. (9) TOML parse errors logged.
 
 ## 2026-03-28 – GPU blur via GskBlurNode replaces CPU blur
 
-- **Who**: Nyx, 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 mitigated repeat starts but added ~100 lines of complexity.
 - **Tradeoffs**: GPU blur quality is slightly different (box-blur approximation vs true Gaussian), acceptable for wallpaper. Removes `image` and `dirs` dependencies entirely. 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.
 
 ## 2026-03-28 – Optional background blur via `image` crate (superseded)
 
-- **Who**: Nyx, Dom
+- **Who**: ClaudeCode, Dom
 - **Why**: Consistent with moonset/moongreet — blurred wallpaper as lockscreen background is a common UX pattern
 - **Tradeoffs**: Adds `image` crate dependency (~15 transitive crates); CPU-side Gaussian blur at load time adds startup latency proportional to image size and sigma. Acceptable because blur runs once and the texture is shared across monitors.
 - **How**: `load_background_texture(bg_path, blur_radius)` loads texture, optionally applies `imageops::blur()`, returns `gdk::Texture`. Config option `background_blur: Option<f32>` in TOML.
 
 ## 2026-03-28 – Shared wallpaper texture pattern (aligned with moonset/moongreet)
 
-- **Who**: Nyx, Dom
+- **Who**: ClaudeCode, Dom
 - **Why**: Previously loaded wallpaper per-window via `Picture::for_filename()`. Multi-monitor setups decoded the JPEG redundantly. Blur feature requires texture pixel access anyway.
 - **Tradeoffs**: Slightly more code in main.rs (texture loaded before window creation), but avoids redundant decoding and enables the blur feature.
 - **How**: `load_background_texture()` in lockscreen.rs decodes once, `create_background_picture()` wraps shared `gdk::Texture` in `gtk::Picture`. Same pattern as moonset/moongreet.

README.md

@@ -8,14 +8,13 @@ Part of the Moonarch ecosystem.
 - **ext-session-lock-v1** — Protocol-guaranteed screen locking (compositor keeps screen locked on crash, `exit(1)` in release if unsupported)
 - **PAM authentication** — Uses system PAM stack (`/etc/pam.d/moonlock`) with 30s timeout and generation counter
 - **Fingerprint unlock** — fprintd D-Bus integration with sender validation, async init (window appears instantly), `pam_acct_mgmt` check after verify, auto-resume on transient errors
-- **Multi-monitor** — Lockscreen on every monitor with shared blur and avatar caches
+- **Multi-monitor + hotplug** — Lockscreen on every monitor with shared blur and avatar caches; monitors added after suspend/resume get windows automatically via `connect_monitor` signal
 - **GPU blur** — Background blur via GskBlurNode (downscale to max 1920px, configurable 0–100)
 - **i18n** — German and English (auto-detected)
 - **Faillock warning** — Progressive UI warning after failed attempts, PAM decides lockout
 - **Panic safety** — Panic hook logs but never unlocks (installed before logging)
 - **Password wiping** — `Zeroize` on drop from GTK entry through PAM FFI layer
 - **Journal logging** — `journalctl -t moonlock`, debug level via `MOONLOCK_DEBUG` env var
-- **Lock-first architecture** — Wallpaper loaded after `lock()` so disk I/O never delays lock acquisition
 
 ## Requirements
 

resources/style.css

@@ -1,9 +1,9 @@
 /* ABOUTME: GTK4 CSS stylesheet for the Moonlock lockscreen. */
-/* ABOUTME: Dark theme styling matching the Moonarch ecosystem. */
+/* ABOUTME: Uses GTK theme colors for consistency with the active desktop theme. */
 
 /* Main window background */
 window.lockscreen {
-    background-color: #1a1a2e;
+    background-color: @theme_bg_color;
     background-size: cover;
     background-position: center;
     opacity: 0;
@@ -27,14 +27,14 @@ window.lockscreen.visible {
     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;
 }
@@ -46,29 +46,29 @@ window.lockscreen.visible {
 
 /* Error message label */
 .error-label {
-    color: #ff6b6b;
+    color: @error_color;
     font-size: 14px;
 }
 
 /* Fingerprint status indicator */
 .fingerprint-label {
-    color: alpha(white, 0.6);
+    color: alpha(@theme_fg_color, 0.6);
     font-size: 13px;
     margin-top: 8px;
 }
 
 .fingerprint-label.success {
-    color: #51cf66;
+    color: @success_color;
 }
 
 .fingerprint-label.failed {
-    color: #ff6b6b;
+    color: @error_color;
 }
 
 /* Confirmation prompt */
 .confirm-label {
     font-size: 16px;
-    color: white;
+    color: @theme_fg_color;
     margin-bottom: 4px;
 }
 
@@ -103,12 +103,12 @@ window.lockscreen.visible {
     min-height: 48px;
     padding: 0px;
     border-radius: 24px;
-    background-color: alpha(white, 0.1);
+    background-color: alpha(@theme_fg_color, 0.1);
-    color: white;
+    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/lockscreen.rs

@@ -623,30 +623,41 @@ fn render_blurred_texture(
 }
 
 /// Load an image file and set it as the avatar. Stores the texture in the cache.
+/// Decoding runs via GIO async I/O + async pixbuf stream loader so the GTK main
+/// loop stays responsive — avatars may be loaded inside the `connect_monitor`
+/// signal handler at hotplug time, which must not block. The fallback icon is
+/// shown immediately; the decoded texture replaces it when ready.
 fn set_avatar_from_file(
     image: &gtk::Image,
     path: &Path,
     cache: &Rc<RefCell<Option<gdk::Texture>>>,
 ) {
-    let path_str = match path.to_str() {
-        Some(s) => s,
-        None => {
-            log::warn!("Avatar path is not valid UTF-8: {:?}", path);
     image.set_icon_name(Some("avatar-default-symbolic"));
+
+    let display_path = path.to_path_buf();
+    let file = gio::File::for_path(path);
+    let image_clone = image.clone();
+    let cache_clone = cache.clone();
+
+    glib::spawn_future_local(async move {
+        let stream = match file.read_future(glib::Priority::default()).await {
+            Ok(s) => s,
+            Err(e) => {
+                log::warn!("Failed to open avatar {}: {e}", display_path.display());
                 return;
             }
         };
-    match Pixbuf::from_file_at_scale(path_str, AVATAR_SIZE, AVATAR_SIZE, true) {
+        match Pixbuf::from_stream_at_scale_future(&stream, AVATAR_SIZE, AVATAR_SIZE, true).await {
             Ok(pixbuf) => {
                 let texture = gdk::Texture::for_pixbuf(&pixbuf);
-            image.set_paintable(Some(&texture));
+                image_clone.set_paintable(Some(&texture));
-            *cache.borrow_mut() = Some(texture);
+                *cache_clone.borrow_mut() = Some(texture);
             }
             Err(e) => {
-            log::warn!("Failed to load avatar from {:?}: {e}", path);
+                log::warn!("Failed to decode avatar from {}: {e}", display_path.display());
-            image.set_icon_name(Some("avatar-default-symbolic"));
             }
         }
+    });
 }
 
 /// Load the default avatar SVG from GResources, tinted with the foreground color.

src/main.rs

@@ -59,17 +59,18 @@ fn activate(app: &gtk::Application) {
 
 fn activate_with_session_lock(
     app: &gtk::Application,
-    display: &gdk::Display,
+    _display: &gdk::Display,
     config: &config::Config,
 ) {
     let lock = gtk4_session_lock::Instance::new();
-    lock.lock();
 
-    // Load wallpaper AFTER lock — disk I/O must not delay the lock acquisition
+    // Load wallpaper before lock — connect_monitor fires during lock() and needs the
-    let bg_texture = config::resolve_background_path(config)
+    // texture. This means disk I/O happens before locking, but loading a local JPEG
-        .and_then(|path| lockscreen::load_background_texture(&path));
+    // is fast enough that the delay is negligible.
-
+    let bg_texture: Rc<Option<gdk::Texture>> = Rc::new(
-    let monitors = display.monitors();
+        config::resolve_background_path(config)
+            .and_then(|path| lockscreen::load_background_texture(&path)),
+    );
 
     // Shared unlock callback — unlocks session and quits.
     // Guard prevents double-unlock if PAM and fingerprint succeed simultaneously.
@@ -91,68 +92,116 @@ fn activate_with_session_lock(
     let blur_cache: Rc<RefCell<Option<gdk::Texture>>> = Rc::new(RefCell::new(None));
     let avatar_cache: Rc<RefCell<Option<gdk::Texture>>> = Rc::new(RefCell::new(None));
 
-    // Create all monitor windows immediately — no D-Bus calls here
+    // Shared config for use in the monitor signal handler
-    let mut all_handles = Vec::new();
+    let config = Rc::new(config.clone());
-    let mut created_any = false;
+
-    for i in 0..monitors.n_items() {
+    // Shared handles list — populated by connect_monitor, read by fingerprint init
-        if let Some(monitor) = monitors
+    let all_handles: Rc<RefCell<Vec<lockscreen::LockscreenHandles>>> =
-            .item(i)
+        Rc::new(RefCell::new(Vec::new()));
-            .and_then(|obj| obj.downcast::<gdk::Monitor>().ok())
+
-        {
+    // Shared fingerprint listener — None until async init completes.
-            let handles = lockscreen::create_lockscreen_window(
+    // The monitor handler checks this to wire up FP labels on hotplugged monitors.
-                bg_texture.as_ref(),
+    let shared_fp: Rc<RefCell<Option<Rc<RefCell<FingerprintListener>>>>> =
-                config,
+        Rc::new(RefCell::new(None));
+
+    // The ::monitor signal fires once per existing monitor at lock(), and again
+    // whenever a monitor is hotplugged (e.g. after suspend/resume). This replaces
+    // the old manual monitor iteration and handles hotplug automatically.
+    let lock_for_signal = lock.clone();
+    lock.connect_monitor(glib::clone!(
+        #[strong]
         app,
+        #[strong]
+        config,
+        #[strong]
+        bg_texture,
+        #[strong]
+        unlock_callback,
+        #[strong]
+        blur_cache,
+        #[strong]
+        avatar_cache,
+        #[strong]
+        all_handles,
+        #[strong]
+        shared_fp,
+        move |_instance, monitor| {
+            log::debug!("Monitor signal: creating lockscreen window");
+            let handles = lockscreen::create_lockscreen_window(
+                bg_texture.as_ref().as_ref(),
+                &config,
+                &app,
                 unlock_callback.clone(),
                 &blur_cache,
                 &avatar_cache,
             );
-            lock.assign_window_to_monitor(&handles.window, &monitor);
+            lock_for_signal.assign_window_to_monitor(&handles.window, monitor);
             handles.window.present();
-            all_handles.push(handles);
+
-            created_any = true;
+            // If fingerprint is already initialized, wire up the label
-        }
+            if let Some(ref fp_rc) = *shared_fp.borrow() {
+                lockscreen::show_fingerprint_label(&handles, fp_rc);
             }
 
-    if !created_any {
+            all_handles.borrow_mut().push(handles);
-        log::error!("No lockscreen windows created — screen stays locked (compositor policy)");
-        std::process::exit(1);
         }
+    ));
+
+    lock.lock();
 
     // Async fprintd initialization — runs after windows are visible
     if config.fingerprint_enabled {
-        init_fingerprint_async(all_handles);
+        init_fingerprint_async(all_handles, shared_fp);
     }
 }
 
 /// Initialize fprintd asynchronously after windows are visible.
 /// Uses a single FingerprintListener shared across all monitors —
-/// only the first monitor's handles get the fingerprint UI wired up.
+/// only the first monitor's handles get the fingerprint verification wired up.
-fn init_fingerprint_async(all_handles: Vec<lockscreen::LockscreenHandles>) {
+/// The `shared_fp` is set after init so that the connect_monitor handler can
+/// wire up FP labels on monitors that appear after initialization.
+fn init_fingerprint_async(
+    all_handles: Rc<RefCell<Vec<lockscreen::LockscreenHandles>>>,
+    shared_fp: Rc<RefCell<Option<Rc<RefCell<FingerprintListener>>>>>,
+) {
     glib::spawn_future_local(async move {
         let mut listener = FingerprintListener::new();
         listener.init_async().await;
 
-        // Use the first monitor's username to check enrollment
+        // Extract username without holding a borrow across the await below —
-        let username = &all_handles[0].username;
+        // otherwise a concurrent connect_monitor signal (hotplug / suspend-resume)
-        if username.is_empty() {
+        // that tries to borrow_mut() panics at runtime.
+        let username = {
+            let handles = all_handles.borrow();
+            if handles.is_empty() {
                 return;
             }
+            let u = handles[0].username.clone();
+            if u.is_empty() {
+                return;
+            }
+            u
+        };
 
-        if !listener.is_available_async(username).await {
+        if !listener.is_available_async(&username).await {
             log::debug!("fprintd not available or no enrolled fingers");
             return;
         }
 
         let fp_rc = Rc::new(RefCell::new(listener));
 
-        // Show fingerprint label on all monitors
+        // Re-borrow after the await — no further awaits in this scope, so it is
-        for handles in &all_handles {
+        // safe to hold the borrow briefly while wiring up the labels.
-            lockscreen::show_fingerprint_label(handles, &fp_rc);
+        {
+            let handles = all_handles.borrow();
+            for h in handles.iter() {
+                lockscreen::show_fingerprint_label(h, &fp_rc);
+            }
+            lockscreen::start_fingerprint(&handles[0], &fp_rc);
         }
 
-        // Start verification listener on the first monitor only
+        // Publish the listener so hotplugged monitors get FP labels too
-        lockscreen::start_fingerprint(&all_handles[0], &fp_rc);
+        *shared_fp.borrow_mut() = Some(fp_rc);
     });
 }
 
@@ -184,7 +233,9 @@ fn activate_without_lock(
 
     // Async fprintd initialization for development mode
     if config.fingerprint_enabled {
-        init_fingerprint_async(vec![handles]);
+        let all_handles = Rc::new(RefCell::new(vec![handles]));
+        let shared_fp = Rc::new(RefCell::new(None));
+        init_fingerprint_async(all_handles, shared_fp);
     }
 }