micro optimization fixes

compositor/src/backends/direct.rs

@@ -773,7 +773,13 @@ fn lid_hides_panel(closed: bool, external_available: bool) -> bool {
     closed && external_available
 }
 
-fn render_output(state: &mut Ferese, node: DrmNode, crtc: crtc::Handle, plan: crate::frame_scheduler::FramePlan) {
+// Return the sampled scene's activity so dispatch does not rescan the windows.
+fn render_output(
+    state: &mut Ferese,
+    node: DrmNode,
+    crtc: crtc::Handle,
+    plan: crate::frame_scheduler::FramePlan,
+) -> bool {
     if state.session_lock.active && state.session_lock.sleeping {
         sleep_locked_outputs(state);
         let asleep = state
@@ -783,7 +789,7 @@ fn render_output(state: &mut Ferese, node: DrmNode, crtc: crtc::Handle, plan: cr
             .and_then(|device| device.outputs.get(&crtc))
             .is_none_or(|output| output.power_off || output.frame_pending);
         if asleep {
-            return;
+            return false;
         }
     }
 
@@ -798,18 +804,18 @@ fn render_output(state: &mut Ferese, node: DrmNode, crtc: crtc::Handle, plan: cr
         .as_mut()
         .and_then(|backend| backend.devices.remove(&node))
     else {
-        return;
+        return false;
     };
 
     let Some(mut output) = device.outputs.remove(&crtc) else {
         restore_device(state, node, device);
-        return;
+        return false;
     };
 
     if !device.drm.is_active() || output.frame_pending {
         device.outputs.insert(crtc, output);
         restore_device(state, node, device);
-        return;
+        return false;
     }
 
     let render_started = Instant::now();
@@ -826,7 +832,7 @@ fn render_output(state: &mut Ferese, node: DrmNode, crtc: crtc::Handle, plan: cr
             let effects = frame_effect_metrics(&elements, output.output.current_scale().fractional_scale());
             let flags = planes::frame_flags(
                 state.output_has_fullscreen_for_frame(&output.output, frame.overview.is_presenting()),
-                state.output_has_animations(&output.output),
+                frame.animating,
                 state.session_lock.active,
             );
             let result =
@@ -919,6 +925,8 @@ fn render_output(state: &mut Ferese, node: DrmNode, crtc: crtc::Handle, plan: cr
     if !submitted {
         schedule_frame_callbacks(state, node, crtc, plan.present_at);
     }
+
+    frame.animating
 }
 
 fn restore_device(state: &mut Ferese, node: DrmNode, device: DirectDevice) {

compositor/src/backends/direct/scheduling.rs

@@ -120,8 +120,9 @@ fn dispatch_frame(state: &mut Ferese, node: DrmNode, crtc: crtc::Handle, identit
         backend.animation_active = animating;
     }
 
-    render_output(state, node, crtc, plan);
-    if state.output_has_animations(identity) {
+    let output_animating = render_output(state, node, crtc, plan);
+
+    if output_animating {
         request_frame(state, node, crtc);
     }
 

compositor/src/config.rs

@@ -11,9 +11,9 @@ use std::path::PathBuf;
 
 use appearance::*;
 pub use appearance::{BorderGradient, InactiveDimSettings, MaterialStyle, ThemeSettings};
-pub(crate) use bindings::physical_keymap;
 use bindings::*;
 pub use bindings::{Binding, BindingAction};
+pub(crate) use bindings::{BindingSet, physical_keymap};
 use ferese_animation::SpringConfig;
 use ferese_core::LayoutMode;
 use ferese_layout::{ColumnWidth, Direction, GapConfig, ViewportFocusStrategy};
@@ -939,18 +939,19 @@ mod tests {
         assert!(bindings.iter().any(|binding| {
             binding.modifiers.logo
                 && binding.trigger == BindingTrigger::Keysym(keysyms::KEY_Return)
-                && binding.action == BindingAction::Spawn(vec!["foot".to_owned()])
+                && binding.action == BindingAction::Spawn(vec!["foot".to_owned()].into())
         }));
         assert!(bindings.iter().any(|binding| {
             binding.modifiers.logo
                 && binding.modifiers.shift
                 && binding.trigger == BindingTrigger::Keysym(keysyms::KEY_s)
-                && binding.action == BindingAction::Spawn(vec!["ferese-screenshot".to_owned()])
+                && binding.action == BindingAction::Spawn(vec!["ferese-screenshot".to_owned()].into())
         }));
         assert!(bindings.iter().any(|binding| {
             binding.trigger == BindingTrigger::Keysym(keysyms::KEY_Print)
                 && binding.modifiers == BindingModifiers::default()
-                && binding.action == BindingAction::Spawn(vec!["ferese-screenshot".to_owned(), "--full".to_owned()])
+                && binding.action
+                    == BindingAction::Spawn(vec!["ferese-screenshot".to_owned(), "--full".to_owned()].into())
         }));
         assert!(bindings.iter().any(|binding| {
             binding.modifiers.logo
@@ -970,7 +971,8 @@ mod tests {
         let bindings = replaced.bindings(&input).unwrap();
         assert_eq!(bindings.len(), 53);
         assert!(bindings.iter().any(|binding| {
-            binding.action == BindingAction::Spawn(vec!["foot".to_owned(), "--app-id".to_owned(), "work".to_owned()])
+            binding.action
+                == BindingAction::Spawn(vec!["foot".to_owned(), "--app-id".to_owned(), "work".to_owned()].into())
         }));
 
         let input = unbound.input_settings().unwrap();

compositor/src/config/bindings.rs

@@ -1,5 +1,10 @@
+use std::sync::Arc;
+
 use super::*;
 
+mod index;
+pub(crate) use index::BindingSet;
+
 impl Config {
     pub fn bindings(&self, input: &InputSettings) -> Result<Vec<Binding>, ConfigError> {
         let mut commands = HashMap::from([
@@ -280,7 +285,7 @@ pub(super) fn parse_action(
             let argv = commands
                 .get(command)
                 .ok_or_else(|| ConfigError::Binding(format!("unknown command {command:?}")))?;
-            Ok(BindingAction::Spawn(argv.clone()))
+            Ok(BindingAction::Spawn(argv.clone().into()))
         }
         "close" => {
             no_argument()?;
@@ -440,7 +445,7 @@ pub(super) struct BindingModifiers {
 #[derive(Clone, Debug, PartialEq)]
 pub enum BindingAction {
     None,
-    Spawn(Vec<String>),
+    Spawn(Arc<[String]>),
     Close,
     Exit,
     Focus(ferese_layout::Direction),

compositor/src/config/bindings/index.rs

@@ -0,0 +1,179 @@
+use super::*;
+
+/// Immutable bindings and their keyboard index are replaced together on reload.
+/// The ordered slice remains available for gestures and the shortcut guide.
+pub(crate) struct BindingSet {
+    ordered: Vec<Binding>,
+    keyboard: HashMap<BindingIdentity, usize>,
+}
+
+impl From<Vec<Binding>> for BindingSet {
+    fn from(ordered: Vec<Binding>) -> Self {
+        let mut keyboard = HashMap::with_capacity(ordered.len());
+
+        for (index, binding) in ordered.iter().enumerate() {
+            let identity = binding_identity_for_runtime(binding);
+
+            if identity.match_mode != BindingMatch::Swipe {
+                keyboard.entry(identity).or_insert(index);
+            }
+        }
+
+        Self { ordered, keyboard }
+    }
+}
+
+impl std::ops::Deref for BindingSet {
+    type Target = [Binding];
+
+    fn deref(&self) -> &Self::Target {
+        &self.ordered
+    }
+}
+
+impl BindingSet {
+    pub(crate) fn action_for_key(
+        &self,
+        keycode: Keycode,
+        symbols: &[u32],
+        logo: bool,
+        ctrl: bool,
+        alt: bool,
+        shift: bool,
+    ) -> Option<&BindingAction> {
+        let modifiers = BindingModifiers { logo, ctrl, alt, shift };
+        let physical = self.keyboard.get(&BindingIdentity {
+            modifiers,
+            match_mode: BindingMatch::Physical,
+            key: keycode.raw(),
+        });
+        let symbolic = symbols.iter().filter_map(|&key| {
+            self.keyboard.get(&BindingIdentity {
+                modifiers,
+                match_mode: BindingMatch::Keysym,
+                key,
+            })
+        });
+        // Preserve list precedence across physical keys and all raw symbols;
+        // neither hash iteration order nor symbol order determines the winner.
+        physical
+            .into_iter()
+            .chain(symbolic)
+            .min()
+            .map(|&index| &self.ordered[index].action)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn binding_for(trigger: BindingTrigger, action: BindingAction) -> Binding {
+        Binding {
+            modifiers: BindingModifiers::default(),
+            trigger,
+            action,
+        }
+    }
+
+    #[test]
+    fn keyboard_index_preserves_order_across_symbols_and_physical_keys() {
+        let code = Keycode::new(38);
+        let bindings = vec![
+            binding_for(BindingTrigger::Keysym(keysyms::KEY_b), BindingAction::Close),
+            binding_for(BindingTrigger::Physical(code), BindingAction::ToggleFloating),
+            binding_for(BindingTrigger::Keysym(keysyms::KEY_a), BindingAction::Exit),
+            binding_for(BindingTrigger::Keysym(keysyms::KEY_b), BindingAction::None),
+        ];
+
+        for ordered in [bindings.clone(), bindings.into_iter().rev().collect()] {
+            let index = BindingSet::from(ordered);
+
+            for symbols in [
+                vec![keysyms::KEY_a, keysyms::KEY_b],
+                vec![keysyms::KEY_b, keysyms::KEY_a],
+                vec![],
+            ] {
+                let expected = index
+                    .iter()
+                    .find(|binding| binding.matches(code, &symbols, false, false, false, false));
+                assert_eq!(
+                    index.action_for_key(code, &symbols, false, false, false, false),
+                    expected.map(|binding| &binding.action)
+                );
+            }
+        }
+    }
+
+    #[test]
+    fn indexed_lookup_matches_linear_lookup_for_all_modifier_combinations() {
+        let config = Config::default();
+        let mut bindings = config.bindings(&config.input_settings().unwrap()).unwrap();
+        bindings.extend([
+            binding_for(BindingTrigger::Physical(Keycode::new(38)), BindingAction::None),
+            binding_for(BindingTrigger::Keysym(keysyms::KEY_a), BindingAction::Close),
+            binding_for(
+                BindingTrigger::Swipe {
+                    fingers: 3,
+                    direction: crate::gestures::SwipeDirection::Left,
+                },
+                BindingAction::Focus(Direction::Left),
+            ),
+        ]);
+        let index = BindingSet::from(bindings);
+
+        for bits in 0..16 {
+            let (logo, ctrl, alt, shift) = (bits & 1 != 0, bits & 2 != 0, bits & 4 != 0, bits & 8 != 0);
+
+            for code in 8..100 {
+                for symbols in [
+                    vec![],
+                    vec![keysyms::KEY_Return],
+                    vec![keysyms::KEY_b, keysyms::KEY_a],
+                    vec![keysyms::KEY_a, keysyms::KEY_Tab],
+                    vec![keysyms::KEY_NoSymbol],
+                ] {
+                    let code = Keycode::new(code);
+                    let expected = index
+                        .iter()
+                        .find(|binding| binding.matches(code, &symbols, logo, ctrl, alt, shift));
+                    assert_eq!(
+                        index.action_for_key(code, &symbols, logo, ctrl, alt, shift),
+                        expected.map(|binding| &binding.action)
+                    );
+                }
+            }
+        }
+    }
+
+    #[test]
+    fn replacing_bindings_discards_old_index_entries() {
+        let code = Keycode::new(38);
+        let mut bindings = BindingSet::from(vec![binding_for(BindingTrigger::Physical(code), BindingAction::Close)]);
+        assert_eq!(
+            bindings.action_for_key(code, &[], false, false, false, false),
+            Some(&BindingAction::Close)
+        );
+        bindings = BindingSet::from(vec![binding_for(
+            BindingTrigger::Keysym(keysyms::KEY_b),
+            BindingAction::None,
+        )]);
+        assert_eq!(bindings.action_for_key(code, &[], false, false, false, false), None);
+        assert_eq!(
+            bindings.action_for_key(code, &[keysyms::KEY_b], false, false, false, false),
+            Some(&BindingAction::None)
+        );
+    }
+
+    #[test]
+    fn cloning_spawn_actions_shares_the_command_storage() {
+        let action = BindingAction::Spawn(vec!["foot".into(), "--app-id".into(), "work".into()].into());
+        let cloned = action.clone();
+        let (BindingAction::Spawn(original), BindingAction::Spawn(cloned)) = (&action, cloned) else {
+            unreachable!();
+        };
+        assert!(Arc::ptr_eq(original, &cloned));
+        assert_eq!(original[0], "foot");
+        assert_eq!(original.len(), 3);
+    }
+}

compositor/src/dimming.rs

@@ -27,6 +27,10 @@ pub(crate) struct DimAnimation {
 }
 
 impl DimAnimation {
+    pub(crate) fn needs_update(&self, target: f64) -> bool {
+        self.target != target || self.current != target
+    }
+
     pub(crate) fn is_animating(&self) -> bool {
         self.current != self.target
     }

compositor/src/handlers/compositor.rs

@@ -84,6 +84,7 @@ impl CompositorHandler for Ferese {
                     } else if self.windows.ids().contains_key(&window) {
                         self.remove_tiled_window(&window);
                         self.space.map_element(window.clone(), (0, 0), false);
+                        self.invalidate_window_stacking();
                         self.restore_keyboard_focus();
                     }
                     if window

compositor/src/handlers/mod.rs

@@ -59,14 +59,7 @@ impl SeatHandler for Ferese {
     }
 
     fn focus_changed(&mut self, seat: &Seat<Self>, focused: Option<&WlSurface>) {
-        if let Some(id) = focused.and_then(|surface| {
-            self.windows.ids().iter().find_map(|(window, id)| {
-                window
-                    .toplevel()
-                    .is_some_and(|toplevel| toplevel.wl_surface() == surface)
-                    .then_some(*id)
-            })
-        }) {
+        if let Some(id) = focused.and_then(|surface| self.windows.id_for_surface(surface)) {
             self.focus_history.record(id);
         }
         if let Some(inhibitor) = self.active_shortcuts_inhibitor.take()
@@ -152,12 +145,7 @@ impl Ferese {
         {
             root = parent;
         }
-        let window = self.windows.ids().iter().find_map(|(window, id)| {
-            window
-                .toplevel()
-                .is_some_and(|toplevel| toplevel.wl_surface() == &root)
-                .then_some(*id)
-        });
+        let window = self.windows.id_for_surface(&root);
         let output = self.space.outputs().find(|output| {
             window.is_some_and(|id| self.window_belongs_to_output(id, output))
                 || layer_map_for_output(output)

compositor/src/handlers/xdg_shell.rs

@@ -30,25 +30,38 @@ impl XdgShellHandler for Ferese {
         // discoverable, but do not mutate/focus the layout until its initial
         // commit supplies the metadata needed to resolve placement rules.
         self.space.map_element(window, (0, 0), false);
+        self.invalidate_window_stacking();
+    }
+
+    fn title_changed(&mut self, surface: ToplevelSurface) {
+        if self.windows.refresh_metadata(surface.wl_surface()) {
+            self.send_shell_snapshots();
+            self.cursor_redraw_pending = true;
+        }
+    }
+
+    fn app_id_changed(&mut self, surface: ToplevelSurface) {
+        if self.windows.refresh_metadata(surface.wl_surface()) {
+            self.send_shell_snapshots();
+            self.cursor_redraw_pending = true;
+        }
     }
 
     fn parent_changed(&mut self, surface: ToplevelSurface) {
         let Some(parent) = surface.parent() else {
             return;
         };
-        let parent = self.windows.ids().iter().find_map(|(window, id)| {
-            window
-                .toplevel()
-                .is_some_and(|toplevel| toplevel.wl_surface() == &parent)
-                .then_some(*id)
-        });
+        let parent = self.windows.id_for_surface(&parent);
         let child = self
-            .space
-            .elements()
-            .find(|window| {
-                window
-                    .toplevel()
-                    .is_some_and(|toplevel| toplevel.wl_surface() == surface.wl_surface())
+            .windows
+            .id_for_surface(surface.wl_surface())
+            .and_then(|id| self.windows.window(id))
+            .or_else(|| {
+                self.space.elements().find(|window| {
+                    window
+                        .toplevel()
+                        .is_some_and(|toplevel| toplevel.wl_surface() == surface.wl_surface())
+                })
             })
             .cloned();
 
@@ -61,13 +74,14 @@ impl XdgShellHandler for Ferese {
         // Hidden workspace windows are managed but unmapped from Space.
         let Some(window) = self
             .windows
-            .ids()
-            .keys()
-            .chain(self.space.elements())
-            .find(|window| {
-                window
-                    .toplevel()
-                    .is_some_and(|toplevel| toplevel.wl_surface() == surface.wl_surface())
+            .id_for_surface(surface.wl_surface())
+            .and_then(|id| self.windows.window(id))
+            .or_else(|| {
+                self.space.elements().find(|window| {
+                    window
+                        .toplevel()
+                        .is_some_and(|toplevel| toplevel.wl_surface() == surface.wl_surface())
+                })
             })
             .cloned()
         else {
@@ -186,12 +200,7 @@ impl XdgShellHandler for Ferese {
     }
 
     fn maximize_request(&mut self, surface: ToplevelSurface) {
-        if let Some(id) = self.windows.ids().iter().find_map(|(window, id)| {
-            window
-                .toplevel()
-                .is_some_and(|toplevel| toplevel.wl_surface() == surface.wl_surface())
-                .then_some(*id)
-        }) {
+        if let Some(id) = self.windows.id_for_surface(surface.wl_surface()) {
             self.set_window_maximized(id, true);
         } else {
             surface.with_pending_state(|state| state.states.set(ToplevelState::Maximized));
@@ -199,12 +208,7 @@ impl XdgShellHandler for Ferese {
     }
 
     fn unmaximize_request(&mut self, surface: ToplevelSurface) {
-        if let Some(id) = self.windows.ids().iter().find_map(|(window, id)| {
-            window
-                .toplevel()
-                .is_some_and(|toplevel| toplevel.wl_surface() == surface.wl_surface())
-                .then_some(*id)
-        }) {
+        if let Some(id) = self.windows.id_for_surface(surface.wl_surface()) {
             self.set_window_maximized(id, false);
         } else {
             surface.with_pending_state(|state| state.states.unset(ToplevelState::Maximized));
@@ -216,12 +220,7 @@ impl XdgShellHandler for Ferese {
         surface: ToplevelSurface,
         _output: Option<smithay::reexports::wayland_server::protocol::wl_output::WlOutput>,
     ) {
-        if let Some(window) = self.windows.ids().iter().find_map(|(window, id)| {
-            window
-                .toplevel()
-                .is_some_and(|toplevel| toplevel.wl_surface() == surface.wl_surface())
-                .then_some(*id)
-        }) {
+        if let Some(window) = self.windows.id_for_surface(surface.wl_surface()) {
             self.set_window_fullscreen(window, true);
         } else {
             surface.with_pending_state(|state| state.states.set(ToplevelState::Fullscreen));
@@ -229,12 +228,7 @@ impl XdgShellHandler for Ferese {
     }
 
     fn unfullscreen_request(&mut self, surface: ToplevelSurface) {
-        if let Some(window) = self.windows.ids().iter().find_map(|(window, id)| {
-            window
-                .toplevel()
-                .is_some_and(|toplevel| toplevel.wl_surface() == surface.wl_surface())
-                .then_some(*id)
-        }) {
+        if let Some(window) = self.windows.id_for_surface(surface.wl_surface()) {
             self.set_window_fullscreen(window, false);
         } else {
             surface.with_pending_state(|state| state.states.unset(ToplevelState::Fullscreen));
@@ -391,14 +385,9 @@ pub fn apply_initial_window_rules(state: &mut Ferese, window: &Window) {
         })
     });
     if initial {
-        let parent = toplevel.parent().and_then(|parent| {
-            state.windows.ids().iter().find_map(|(candidate, id)| {
-                candidate
-                    .toplevel()
-                    .is_some_and(|surface| surface.wl_surface() == &parent)
-                    .then_some(*id)
-            })
-        });
+        let parent = toplevel
+            .parent()
+            .and_then(|parent| state.windows.id_for_surface(&parent));
         state.add_rule_placed_window(window.clone(), app_id.as_deref(), title.as_deref(), parent);
     }
     state.apply_initial_window_rules(window, app_id.as_deref(), title.as_deref(), transient);

compositor/src/input.rs

@@ -364,18 +364,14 @@ impl Ferese {
                             .into_iter()
                             .map(|symbol| symbol.raw())
                             .collect::<Vec<_>>();
-                        let action = data.bindings.iter().find_map(|binding| {
-                            binding
-                                .matches(
-                                    keycode,
-                                    &raw_symbols,
-                                    modifiers.logo,
-                                    modifiers.ctrl,
-                                    modifiers.alt,
-                                    modifiers.shift,
-                                )
-                                .then(|| binding.action.clone())
-                        });
+                        let action = data.bindings.action_for_key(
+                            keycode,
+                            &raw_symbols,
+                            modifiers.logo,
+                            modifiers.ctrl,
+                            modifiers.alt,
+                            modifiers.shift,
+                        );
                         if data.focus_cycle.is_some()
                             && state == KeyState::Pressed
                             && !matches!(action, Some(BindingAction::FocusMru(_)))
@@ -405,6 +401,8 @@ impl Ferese {
 
                         if state == KeyState::Pressed {
                             data.intercepted_keys.insert(keycode);
+                            let action = action.clone();
+
                             if let BindingAction::FocusMru(reverse) = action {
                                 data.cycle_focus(reverse, modifiers.alt);
                             } else {
@@ -814,6 +812,8 @@ impl Ferese {
             return;
         }
 
+        let previous = self.focused_window;
+
         if let Some(window) = self.window_under_visual(position) {
             let focused = self.windows.ids().get(&window).copied();
             if let Some(focused) = focused {
@@ -833,8 +833,21 @@ impl Ferese {
             } else {
                 // Hover transfers keyboard focus without changing the persistent
                 // stack: an exposed window must not cover the floats above it.
-                for mapped in self.space.elements() {
-                    mapped.set_activated(mapped == &window);
+                if let Some(previous) = previous
+                    .filter(|id| Some(*id) != focused)
+                    .and_then(|id| self.windows.window(id))
+                {
+                    previous.set_activated(false);
+
+                    if let Some(toplevel) = previous.toplevel() {
+                        toplevel.send_pending_configure();
+                    }
+                }
+
+                window.set_activated(true);
+
+                if let Some(toplevel) = window.toplevel() {
+                    toplevel.send_pending_configure();
                 }
             }
             let surface = window
@@ -844,16 +857,18 @@ impl Ferese {
                 .clone();
             keyboard.set_focus(self, Some(surface), serial);
         } else {
+            if let Some(previous) = previous.and_then(|id| self.windows.window(id)) {
+                previous.set_activated(false);
+
+                if let Some(toplevel) = previous.toplevel() {
+                    toplevel.send_pending_configure();
+                }
+            }
+
             self.focused_window = None;
             keyboard.set_focus(self, Option::<WlSurface>::None, serial);
         }
 
-        self.space.elements().for_each(|window| {
-            if let Some(toplevel) = window.toplevel() {
-                toplevel.send_pending_configure();
-            }
-        });
-
         if raise {
             self.relayout();
         } else {
@@ -987,11 +1002,11 @@ impl Ferese {
     fn execute_binding(&mut self, action: BindingAction) {
         match action {
             BindingAction::None => {}
-            BindingAction::Spawn(mut argv) => {
-                let program = argv.remove(0);
+            BindingAction::Spawn(argv) => {
+                let (program, args) = argv.split_first().expect("binding commands are validated");
 
-                match Command::new(&program)
-                    .args(argv)
+                match Command::new(program)
+                    .args(args)
                     .env("WAYLAND_DISPLAY", &self.socket_name)
                     .env_remove("WAYLAND_SOCKET")
                     .spawn()

compositor/src/overview.rs

@@ -84,8 +84,17 @@ pub(crate) fn init_font_loader(
     Ok(())
 }
 
-type OverviewStateLabel =
-    HashMap<(String, u64, [u32; 4]), (MemoryRenderBuffer, smithay::utils::Size<i32, smithay::utils::Buffer>)>;
+type LabelBuffer = (MemoryRenderBuffer, smithay::utils::Size<i32, smithay::utils::Buffer>);
+type LabelStyle = (u64, [u32; 4]);
+type OverviewStateLabel = HashMap<String, HashMap<LabelStyle, LabelBuffer>>;
+
+#[derive(Debug)]
+struct WindowLabel {
+    revision: u64,
+    limit: usize,
+    style: LabelStyle,
+    buffer: LabelBuffer,
+}
 
 #[derive(Debug)]
 pub(crate) struct OverviewState {
@@ -97,6 +106,8 @@ pub(crate) struct OverviewState {
     font_requests: Option<FontRequests>,
     font: Option<FontArc>,
     labels: OverviewStateLabel,
+    window_labels: HashMap<WindowId, WindowLabel>,
+    label_count: usize,
 }
 
 #[derive(Clone, Debug)]
@@ -118,6 +129,8 @@ impl Default for OverviewState {
             font_requests: None,
             font: None,
             labels: HashMap::new(),
+            window_labels: HashMap::new(),
+            label_count: 0,
         }
     }
 }
@@ -163,6 +176,17 @@ fn centered_row_start(strip: Rect, count: usize, card_width: f64) -> f64 {
 }
 
 impl OverviewState {
+    pub(crate) fn needs_tick(&self) -> bool {
+        self.motion.exit_transition.is_some()
+            || self.motion.opacity.current != self.motion.opacity.target
+            || self.motion.opacity.velocity != 0.0
+            || self
+                .motion
+                .presentations
+                .values()
+                .any(|rect| rect.current != rect.target || rect.velocity != ferese_animation::RectVelocity::default())
+    }
+
     pub(crate) fn is_animating(&self, spring: SpringConfig) -> bool {
         self.motion.is_animating(spring)
     }
@@ -200,6 +224,8 @@ impl OverviewState {
         }
         self.font = font;
         self.labels.clear();
+        self.window_labels.clear();
+        self.label_count = 0;
         true
     }
 
@@ -209,8 +235,8 @@ impl OverviewState {
         scale: f64,
         color: [f32; 4],
     ) -> Option<(MemoryRenderBuffer, smithay::utils::Size<i32, smithay::utils::Buffer>)> {
-        let key = (text.to_owned(), scale.to_bits(), color.map(f32::to_bits));
-        if let Some(buffer) = self.labels.get(&key) {
+        let key = (scale.to_bits(), color.map(f32::to_bits));
+        if let Some(buffer) = self.labels.get(text).and_then(|styles| styles.get(&key)) {
             return Some(buffer.clone());
         }
         let font = self.font.as_ref()?;
@@ -249,11 +275,16 @@ impl OverviewState {
         }
         let buffer =
             MemoryRenderBuffer::from_slice(&pixels, Fourcc::Abgr8888, (width, height), 1, Transform::Normal, None);
-        if self.labels.len() >= 128 {
+        if self.label_count >= 128 {
             self.labels.clear();
+            self.label_count = 0;
         }
         let label = (buffer, (width, height).into());
-        self.labels.insert(key, label.clone());
+        self.labels
+            .entry(text.to_owned())
+            .or_default()
+            .insert(key, label.clone());
+        self.label_count += 1;
         Some(label)
     }
 
@@ -430,32 +461,53 @@ impl Ferese {
         }
     }
 
-    pub(crate) fn overview_window_label(
-        &mut self,
-        window: &smithay::desktop::Window,
-        scale: f64,
-        width: f64,
-    ) -> Option<(MemoryRenderBuffer, smithay::utils::Size<i32, smithay::utils::Buffer>)> {
-        use smithay::wayland::compositor::with_states;
-        use smithay::wayland::shell::xdg::XdgToplevelSurfaceData;
-        let surface = window.toplevel()?.wl_surface();
-        let title = with_states(surface, |states| {
-            let data = states.data_map.get::<XdgToplevelSurfaceData>()?.lock().ok()?;
-            data.title
-                .clone()
-                .filter(|title| !title.trim().is_empty())
-                .or_else(|| data.app_id.clone())
-        })
-        .unwrap_or_else(|| "Window".into());
-        let limit = ((width - 16.0) / 8.0).clamp(1.0, 48.0) as usize;
-        let mut chars = title.chars().filter(|c| !c.is_control());
-        let mut title: String = chars.by_ref().take(limit).collect();
-        if chars.next().is_some() {
-            title.pop();
-            title.push('…');
-        }
+    pub(crate) fn retain_overview_labels(&mut self) {
         self.overview
-            .label(&title, scale, self.theme_settings.text_primary_color.0)
+            .window_labels
+            .retain(|id, _| self.windows.window(*id).is_some());
+    }
+
+    pub(crate) fn overview_window_label(&mut self, id: WindowId, scale: f64, width: f64) -> Option<LabelBuffer> {
+        let record = self.windows.record(id)?;
+        let limit = ((width - 16.0) / 8.0).clamp(1.0, 48.0) as usize;
+        let color = self.theme_settings.text_primary_color.0;
+        let style = (scale.to_bits(), color.map(f32::to_bits));
+
+        if let Some(label) = self.overview.window_labels.get(&id)
+            && label.revision == record.metadata_revision
+            && label.limit == limit
+            && label.style == style
+        {
+            return Some(label.buffer.clone());
+        }
+
+        let title = if !record.title.trim().is_empty() {
+            &record.title
+        } else if !record.app_id.is_empty() {
+            &record.app_id
+        } else {
+            "Window"
+        };
+        let mut chars = title.chars().filter(|c| !c.is_control());
+        let mut text: String = chars.by_ref().take(limit).collect();
+
+        if chars.next().is_some() {
+            text.pop();
+            text.push('…');
+        }
+
+        let revision = record.metadata_revision;
+        let buffer = self.overview.label(&text, scale, color)?;
+        self.overview.window_labels.insert(
+            id,
+            WindowLabel {
+                revision,
+                limit,
+                style,
+                buffer: buffer.clone(),
+            },
+        );
+        Some(buffer)
     }
 
     pub(crate) fn overview_workspace_label(
@@ -608,9 +660,7 @@ impl Ferese {
         let capacity = strip_capacity(strip);
         let workspaces = self
             .output_workspaces
-            .workspace_views(&self.workspaces)
-            .into_iter()
-            .filter(|view| view.output == output_id)
+            .workspace_views_for_output(&self.workspaces, output_id)
             .collect::<Vec<_>>();
         let selected_index = workspaces
             .iter()
@@ -904,6 +954,15 @@ fn directional_distance(direction: Direction, current: (f64, f64), candidate: (f
 mod tests {
     use super::*;
 
+    #[test]
+    fn tiny_overview_target_changes_still_get_a_settling_tick() {
+        let mut overview = OverviewState::default();
+        assert!(!overview.needs_tick());
+        overview.motion.opacity.set_target(0.0001);
+        assert!(!overview.is_animating(SpringConfig::default()));
+        assert!(overview.needs_tick());
+    }
+
     fn test_font() -> FontArc {
         FontArc::try_from_slice(include_bytes!("../../assets/fonts/Comfortaa-Regular.otf")).unwrap()
     }

compositor/src/presentation.rs

@@ -5,7 +5,6 @@ use std::time::{Duration, Instant};
 use smithay::backend::renderer::element::{
     Element, Id, Kind, RenderElement, RenderElementPresentationState, RenderElementStates,
 };
-use smithay::backend::renderer::gles::element::PixelShaderElement;
 use smithay::backend::renderer::gles::{GlesError, GlesFrame, GlesRenderer, GlesTexProgram, GlesTexture, Uniform};
 use smithay::backend::renderer::utils::{CommitCounter, DamageSet};
 use smithay::desktop::utils::OutputPresentationFeedback;
@@ -15,6 +14,8 @@ use smithay::reexports::wayland_server::protocol::wl_surface::WlSurface;
 use smithay::utils::{Buffer, Logical, Physical, Point, Rectangle, Scale, Transform};
 use smithay::wayland::compositor::SurfaceData;
 
+use crate::render::SharedPixelShaderElement;
+
 pub(crate) const HANDOFF: Duration = Duration::from_millis(80);
 pub(crate) const SNAPSHOT_BUDGET: usize = 64 * 1024 * 1024;
 
@@ -164,7 +165,7 @@ pub(crate) fn advance_handoff(
 /// A shader canvas whose damage/paint destination uses the shared pixel edges.
 #[derive(Clone, Debug)]
 pub(crate) struct PhysicalShaderElement {
-    pub inner: PixelShaderElement,
+    pub inner: SharedPixelShaderElement,
     pub geometry: Rectangle<i32, Physical>,
 }
 

compositor/src/render/decorations.rs

@@ -130,7 +130,7 @@ pub(super) fn window_border_element(
     let context = renderer.context_id().erased();
     let buffers = &mut resources.windows.entry(id).or_default().borders;
     if !buffers.contexts.contains_key(&context) {
-        let element = PixelShaderElement::new(
+        let element = SharedPixelShaderElement::new(
             programs.border.clone(),
             geometry,
             None,
@@ -164,16 +164,16 @@ pub(super) fn window_border_element(
 
 pub(super) fn border_uniforms(parameters: &BorderParameters) -> Vec<Uniform<'static>> {
     vec![
-        Uniform::new("clip_rect", parameters.clip_rect).into_owned(),
-        Uniform::new("radius", parameters.radius).into_owned(),
-        Uniform::new("border_width", parameters.width).into_owned(),
-        Uniform::new("border_color", parameters.color).into_owned(),
-        Uniform::new("border_color_to", parameters.color_to).into_owned(),
-        Uniform::new("gradient_line", parameters.gradient_line).into_owned(),
-        Uniform::new("focus_color", parameters.focus_color).into_owned(),
-        Uniform::new("focus_color_to", parameters.focus_color_to).into_owned(),
-        Uniform::new("focus_gradient_line", parameters.focus_gradient_line).into_owned(),
-        Uniform::new("focus_mix", parameters.focus_mix).into_owned(),
+        Uniform::new("clip_rect", parameters.clip_rect),
+        Uniform::new("radius", parameters.radius),
+        Uniform::new("border_width", parameters.width),
+        Uniform::new("border_color", parameters.color),
+        Uniform::new("border_color_to", parameters.color_to),
+        Uniform::new("gradient_line", parameters.gradient_line),
+        Uniform::new("focus_color", parameters.focus_color),
+        Uniform::new("focus_color_to", parameters.focus_color_to),
+        Uniform::new("focus_gradient_line", parameters.focus_gradient_line),
+        Uniform::new("focus_mix", parameters.focus_mix),
     ]
 }
 
@@ -213,12 +213,12 @@ pub(super) fn window_tint_element(
     };
     let uniforms = |p: &BorderParameters| {
         vec![
-            Uniform::new("visible_rect", p.clip_rect).into_owned(),
-            Uniform::new("material_radius", p.radius).into_owned(),
-            Uniform::new("tint", p.color).into_owned(),
-            Uniform::new("paint_mode", 0.0_f32).into_owned(),
-            Uniform::new("shadow_rect", p.clip_rect).into_owned(),
-            Uniform::new("shadow_values", [0.0_f32; 2]).into_owned(),
+            Uniform::new("visible_rect", p.clip_rect),
+            Uniform::new("material_radius", p.radius),
+            Uniform::new("tint", p.color),
+            Uniform::new("paint_mode", 0.0_f32),
+            Uniform::new("shadow_rect", p.clip_rect),
+            Uniform::new("shadow_values", [0.0_f32; 2]),
         ]
     };
     let context = renderer.context_id().erased();
@@ -228,7 +228,7 @@ pub(super) fn window_tint_element(
         &mut resources.windows.entry(id).or_default().dim
     };
     let cached = buffers.contexts.entry(context).or_insert_with(|| CachedBorder {
-        element: PixelShaderElement::new(
+        element: SharedPixelShaderElement::new(
             program.0,
             geometry,
             None,
@@ -293,7 +293,7 @@ pub(super) fn window_shadow_element(
     let context = renderer.context_id().erased();
     let buffers = &mut resources.windows.entry(id).or_default().shadow;
     if !buffers.contexts.contains_key(&context) {
-        let element = PixelShaderElement::new(
+        let element = SharedPixelShaderElement::new(
             programs.shadow.clone(),
             bounds,
             None,
@@ -331,11 +331,11 @@ pub(super) fn window_shadow_element(
 
 pub(super) fn shadow_uniforms(parameters: &ShadowParameters) -> Vec<Uniform<'static>> {
     vec![
-        Uniform::new("shadow_rect", parameters.shadow_rect).into_owned(),
-        Uniform::new("radius", parameters.radius).into_owned(),
-        Uniform::new("blur", parameters.blur).into_owned(),
-        Uniform::new("opacity", parameters.opacity).into_owned(),
-        Uniform::new("shadow_color", parameters.color).into_owned(),
+        Uniform::new("shadow_rect", parameters.shadow_rect),
+        Uniform::new("radius", parameters.radius),
+        Uniform::new("blur", parameters.blur),
+        Uniform::new("opacity", parameters.opacity),
+        Uniform::new("shadow_color", parameters.color),
     ]
 }
 

compositor/src/render/materials.rs

@@ -248,7 +248,7 @@ pub(super) fn material_element(
                 capture.dirty.clone(),
             ))
         } else {
-            MaterialElement::Fill(PixelShaderElement::new(
+            MaterialElement::Fill(SharedPixelShaderElement::new(
                 program.0.clone(),
                 geometry,
                 parameters.opaque.then(|| vec![Rectangle::from_size(geometry.size)]),
@@ -264,7 +264,7 @@ pub(super) fn material_element(
         .or_insert_with(|| CachedMaterial {
             element: make_element(),
             parameters: parameters.clone(),
-            shadow: PixelShaderElement::new(
+            shadow: SharedPixelShaderElement::new(
                 program.0.clone(),
                 parameters.shadow_bounds,
                 None,
@@ -356,14 +356,14 @@ pub(super) fn blur_uniform_names() -> [UniformName<'static>; 8] {
 
 pub(super) fn blur_uniforms(p: &MaterialParameters) -> Vec<Uniform<'static>> {
     vec![
-        Uniform::new("visible_rect", p.visible_framebuffer).into_owned(),
-        Uniform::new("material_radius", p.radius).into_owned(),
-        Uniform::new("texture_size", [p.sample_framebuffer[2], p.sample_framebuffer[3]]).into_owned(),
-        Uniform::new("capture_origin", [p.sample_framebuffer[0], p.sample_framebuffer[1]]).into_owned(),
-        Uniform::new("blur_radius", p.blur).into_owned(),
-        Uniform::new("presentation_alpha", p.presentation_alpha).into_owned(),
-        Uniform::new("background_opacity", p.background_opacity).into_owned(),
-        Uniform::new("tint", p.tint).into_owned(),
+        Uniform::new("visible_rect", p.visible_framebuffer),
+        Uniform::new("material_radius", p.radius),
+        Uniform::new("texture_size", [p.sample_framebuffer[2], p.sample_framebuffer[3]]),
+        Uniform::new("capture_origin", [p.sample_framebuffer[0], p.sample_framebuffer[1]]),
+        Uniform::new("blur_radius", p.blur),
+        Uniform::new("presentation_alpha", p.presentation_alpha),
+        Uniform::new("background_opacity", p.background_opacity),
+        Uniform::new("tint", p.tint),
     ]
 }
 
@@ -426,12 +426,12 @@ pub(super) fn material_uniforms(parameters: &MaterialParameters) -> Vec<Uniform<
 
 pub(super) fn decoration_uniforms(parameters: &MaterialParameters, paint_mode: f32) -> Vec<Uniform<'static>> {
     vec![
-        Uniform::new("paint_mode", paint_mode).into_owned(),
-        Uniform::new("shadow_rect", parameters.shadow_rect).into_owned(),
-        Uniform::new("shadow_values", parameters.shadow_values).into_owned(),
-        Uniform::new("visible_rect", parameters.visible_framebuffer).into_owned(),
-        Uniform::new("material_radius", parameters.radius).into_owned(),
-        Uniform::new("tint", parameters.tint).into_owned(),
+        Uniform::new("paint_mode", paint_mode),
+        Uniform::new("shadow_rect", parameters.shadow_rect),
+        Uniform::new("shadow_values", parameters.shadow_values),
+        Uniform::new("visible_rect", parameters.visible_framebuffer),
+        Uniform::new("material_radius", parameters.radius),
+        Uniform::new("tint", parameters.tint),
     ]
 }
 

compositor/src/render/mod.rs

@@ -4,6 +4,7 @@ mod materials;
 mod overview;
 mod resources;
 mod scene;
+mod shader;
 use std::collections::HashMap;
 use std::sync::Arc;
 use std::sync::atomic::{AtomicBool, Ordering};
@@ -18,6 +19,7 @@ use scene::cursor_elements;
 pub(crate) use scene::{
     animated_window_elements, frame_effect_metrics, layer_surfaces, output_elements, sampled_output_elements,
 };
+pub(crate) use shader::SharedPixelShaderElement;
 use smithay::backend::allocator::Fourcc;
 use smithay::backend::renderer::element::memory::MemoryRenderBufferRenderElement;
 use smithay::backend::renderer::element::solid::SolidColorRenderElement;
@@ -31,7 +33,6 @@ use smithay::backend::renderer::element::utils::{
 use smithay::backend::renderer::element::{
     Element, Id, Kind as RenderElementKind, RenderElement, UnderlyingStorage, render_elements,
 };
-use smithay::backend::renderer::gles::element::PixelShaderElement;
 use smithay::backend::renderer::gles::{
     GlesError, GlesFrame, GlesPixelProgram, GlesRenderer, GlesTexProgram, GlesTexture, Uniform, UniformName,
     UniformType,
@@ -66,7 +67,7 @@ render_elements! {
     Memory=MemoryRenderElement,
     Solid=SolidColorRenderElement,
     LockSurface=WaylandSurfaceRenderElement<GlesRenderer>,
-    Border=PixelShaderElement,
+    Border=SharedPixelShaderElement,
     Blur=BlurRenderElement,
     Effect=PhysicalShaderElement,
     Native=NativeTextureElement,
@@ -132,7 +133,7 @@ struct BlurRenderElement {
     commit: CommitCounter,
     geometry: Rectangle<i32, Logical>,
     capture_rect: [i32; 4],
-    uniforms: Vec<Uniform<'static>>,
+    uniforms: Arc<[Uniform<'static>]>,
 }
 
 impl BlurRenderElement {
@@ -150,7 +151,7 @@ impl BlurRenderElement {
             commit: CommitCounter::default(),
             geometry: parameters.sample_geometry,
             capture_rect: framebuffer_capture_rect(parameters.sample_framebuffer),
-            uniforms: blur_uniforms(parameters),
+            uniforms: blur_uniforms(parameters).into(),
         }
     }
 
@@ -158,7 +159,7 @@ impl BlurRenderElement {
         self.capture_dirty.store(true, Ordering::Relaxed);
         self.geometry = parameters.sample_geometry;
         self.capture_rect = framebuffer_capture_rect(parameters.sample_framebuffer);
-        self.uniforms = blur_uniforms(parameters);
+        self.uniforms = blur_uniforms(parameters).into();
         self.commit.increment();
     }
 }
@@ -327,7 +328,7 @@ struct MaterialParameters {
 
 #[derive(Clone, Debug)]
 enum MaterialElement {
-    Fill(PixelShaderElement),
+    Fill(SharedPixelShaderElement),
     Blur(BlurRenderElement),
 }
 
@@ -335,7 +336,7 @@ enum MaterialElement {
 struct CachedMaterial {
     element: MaterialElement,
     parameters: MaterialParameters,
-    shadow: PixelShaderElement,
+    shadow: SharedPixelShaderElement,
 }
 
 #[derive(Debug, Default)]
@@ -361,7 +362,7 @@ struct BorderParameters {
 
 #[derive(Debug)]
 struct CachedBorder {
-    element: PixelShaderElement,
+    element: SharedPixelShaderElement,
     parameters: BorderParameters,
 }
 
@@ -382,7 +383,7 @@ struct ShadowParameters {
 
 #[derive(Debug)]
 struct CachedShadow {
-    element: PixelShaderElement,
+    element: SharedPixelShaderElement,
     parameters: ShadowParameters,
 }
 

compositor/src/render/overview.rs

@@ -40,12 +40,12 @@ pub(super) fn overview_chrome_element(
             border_uniforms(p)
         } else {
             vec![
-                Uniform::new("visible_rect", p.clip_rect).into_owned(),
-                Uniform::new("material_radius", p.radius).into_owned(),
-                Uniform::new("tint", p.color).into_owned(),
-                Uniform::new("paint_mode", 0.0_f32).into_owned(),
-                Uniform::new("shadow_rect", p.clip_rect).into_owned(),
-                Uniform::new("shadow_values", [0.0_f32; 2]).into_owned(),
+                Uniform::new("visible_rect", p.clip_rect),
+                Uniform::new("material_radius", p.radius),
+                Uniform::new("tint", p.color),
+                Uniform::new("paint_mode", 0.0_f32),
+                Uniform::new("shadow_rect", p.clip_rect),
+                Uniform::new("shadow_values", [0.0_f32; 2]),
             ]
         }
     };
@@ -61,7 +61,7 @@ pub(super) fn overview_chrome_element(
         .or_default()
         .entry(context)
         .or_insert_with(|| CachedBorder {
-            element: PixelShaderElement::new(
+            element: SharedPixelShaderElement::new(
                 program,
                 geometry,
                 None,
@@ -119,33 +119,31 @@ pub(super) fn overview_strip_elements(
     .opacity;
     let mut elements = Vec::new();
     let programs = rounded_clip_program(&mut state.render, renderer);
-    // Resolve IDs once per strip, rather than scanning all managed windows
-    // separately for every miniature. Own the handles so rendering can mutate state.
-    let windows_by_id: std::collections::HashMap<_, _> = state
-        .windows
-        .ids()
+    state.retain_overview_labels();
+
+    let card_ids = cards
         .iter()
-        .map(|(window, id)| (*id, window.clone()))
-        .collect();
+        .map(|card| card.workspace.0)
+        .collect::<std::collections::HashSet<_>>();
     if let Some(output_id) = state.output_id(output)
         && let Some(cache) = state.render.outputs.get_mut(&output_id)
     {
         cache.chrome.retain(|(id, part), _| match part {
-            OverviewChromePart::Caption => windows_by_id.keys().any(|window| window.0 == *id),
-            OverviewChromePart::Card | OverviewChromePart::Outline => cards.iter().any(|card| card.workspace.0 == *id),
+            OverviewChromePart::Caption => state.windows.window(ferese_layout::WindowId(*id)).is_some(),
+            OverviewChromePart::Card | OverviewChromePart::Outline => card_ids.contains(id),
             OverviewChromePart::Strip => true,
         });
     }
     // Cached title textures are independent of window content and stay readable
     // when thumbnails are small. Their pills use the shell's material and radius.
-    for (id, window) in &windows_by_id {
+    for id in frame.windows.keys() {
         if !state.window_belongs_to_output(*id, output) {
             continue;
         }
         let Some(rect) = frame.windows.get(id).map(|sample| sample.rect) else {
             continue;
         };
-        let Some((buffer, size)) = state.overview_window_label(window, scale, rect.width) else {
+        let Some((buffer, size)) = state.overview_window_label(*id, scale, rect.width) else {
             continue;
         };
         let width = (f64::from(size.w) / scale + 16.0).min(rect.width);
@@ -222,7 +220,7 @@ pub(super) fn overview_strip_elements(
         }
         if let Some(programs) = &programs {
             for (id, rect) in &card.windows {
-                if let Some(window) = windows_by_id.get(id) {
+                if let Some(window) = state.windows.window(*id) {
                     elements.extend(rounded_window_elements(
                         renderer,
                         window,

compositor/src/render/scene.rs

@@ -1,3 +1,5 @@
+use smithay::desktop::Window;
+
 use super::*;
 
 pub(crate) fn animated_window_elements(
@@ -109,39 +111,42 @@ pub(crate) fn sampled_output_elements(
             frame,
         ));
     }
-    let mut candidates = if state.overview.is_active() {
-        state.windows.ids().keys().cloned().collect::<Vec<_>>()
+    let prepare_window = |window: &Window| {
+        // Configure immediately, but present the frame/shadow only after
+        // the first buffer commit has settled the actual client geometry.
+        if !state.window_content_ready(window) {
+            return None;
+        }
+        let id = *state.windows.ids().get(window)?;
+        // Scrolling columns may sit outside their monitor's rectangle.
+        // They must not reappear on a neighboring output just because
+        // their global animated coordinates overlap it.
+        if !state.window_belongs_to_output(id, output) {
+            return None;
+        }
+        let sample = frame.windows.get(&id)?;
+        let visual = scaled_visual_rect(sample.rect, sample.close_scale);
+        let close_alpha = sample.close_alpha;
+        let decoration_progress = sample.geometry.decorations.clamp(0.0, 1.0);
+
+        Some((window.clone(), id, sample, visual, decoration_progress, close_alpha))
+    };
+    let windows = if state.overview.is_active() {
+        state
+            .windows
+            .overview_windows()
+            .filter_map(prepare_window)
+            .collect::<Vec<_>>()
     } else {
-        state.space.elements().rev().cloned().collect::<Vec<_>>()
+        state
+            .space
+            .elements()
+            .rev()
+            .filter_map(prepare_window)
+            .collect::<Vec<_>>()
     };
-    if state.overview.is_active() {
-        candidates.sort_by_key(|window| std::cmp::Reverse(state.windows.ids().get(window).map_or(0, |id| id.0)));
-    }
-    let windows = candidates
-        .iter()
-        .filter_map(|window| {
-            // Configure immediately, but present the frame/shadow only after
-            // the first buffer commit has settled the actual client geometry.
-            if !state.window_content_ready(window) {
-                return None;
-            }
-            let id = *state.windows.ids().get(window)?;
-            // Scrolling columns may sit outside their monitor's rectangle.
-            // They must not reappear on a neighboring output just because
-            // their global animated coordinates overlap it.
-            if !state.window_belongs_to_output(id, output) {
-                return None;
-            }
-            let sample = frame.windows.get(&id)?;
-            let visual = scaled_visual_rect(sample.rect, sample.close_scale);
-            let close_alpha = sample.close_alpha;
-            let decoration_progress = sample.geometry.decorations.clamp(0.0, 1.0);
 
-            Some((window.clone(), id, visual, decoration_progress, close_alpha))
-        })
-        .collect::<Vec<_>>();
-
-    for (window, id, visual, decoration_progress, close_alpha) in windows {
+    for (window, id, sample, visual, decoration_progress, close_alpha) in windows {
         let constrain = rounded_visual_rect(visual, output_geometry.loc);
         let material_surface = window
             .toplevel()
@@ -158,10 +163,10 @@ pub(crate) fn sampled_output_elements(
         let corners = RoundedRect::new(visual, output_geometry.loc, scale, window_radius);
         let pixels = corners.rect;
         // Only overview/close intentionally scale the complete application.
-        let scale_content = frame.overview.is_presenting() || frame.windows[&id].close_scale != 1.0;
+        let scale_content = frame.overview.is_presenting() || sample.close_scale != 1.0;
         let behavior = resize_content_behavior(scale_content);
 
-        let dim = frame.windows[&id].dim;
+        let dim = sample.dim;
         if let Some(overlay) = window_tint_element(
             &mut state.render,
             renderer,
@@ -182,7 +187,7 @@ pub(crate) fn sampled_output_elements(
             let shadow_blur = state.theme_settings.shadow_blur;
             let shadow_opacity = state.theme_settings.shadow_opacity;
             let shadow_color = state.theme_settings.shadow_color.0;
-            let focus = frame.windows[&id].focus;
+            let focus = sample.focus;
             let border_width = state.theme_settings.border_width
                 + (state.theme_settings.focus_ring_width - state.theme_settings.border_width) * focus;
             let border_color = state.theme_settings.border_color.0;
@@ -245,10 +250,7 @@ pub(crate) fn sampled_output_elements(
                             ))),
                             alpha: crate::presentation::handoff_alpha(snapshot.elapsed) * close_alpha,
                             program: Some(programs.texture.clone()),
-                            uniforms: vec![
-                                Uniform::new("clip_rect", clip).into_owned(),
-                                Uniform::new("radius", corners.radius).into_owned(),
-                            ],
+                            uniforms: vec![Uniform::new("clip_rect", clip), Uniform::new("radius", corners.radius)],
                         }
                         .into(),
                     );
@@ -260,7 +262,7 @@ pub(crate) fn sampled_output_elements(
                 corners,
                 scale,
                 close_alpha,
-                frame.windows[&id].geometry.presentation_changed,
+                sample.geometry.presentation_changed,
                 output,
                 programs.clone(),
                 behavior,

compositor/src/render/shader.rs

@@ -0,0 +1,231 @@
+//! Static uniform names stay borrowed; cached frame elements share their state.
+//! Copy on write preserves the ID and commit seen by an already sampled frame.
+use std::sync::Arc;
+
+use smithay::backend::renderer::element::{Element, Id, Kind, RenderElement};
+use smithay::backend::renderer::gles::{GlesError, GlesFrame, GlesPixelProgram, GlesRenderer, Uniform};
+use smithay::backend::renderer::utils::{CommitCounter, OpaqueRegions};
+use smithay::utils::{Buffer, Logical, Physical, Rectangle, Scale, Transform};
+
+#[derive(Clone, Debug)]
+pub(crate) struct SharedPixelShaderElement {
+    shader: GlesPixelProgram,
+    state: Arc<ShaderState>,
+}
+
+#[derive(Clone, Debug)]
+struct ShaderState {
+    id: Id,
+    commit: CommitCounter,
+    area: Rectangle<i32, Logical>,
+    opaque: Vec<Rectangle<i32, Logical>>,
+    alpha: f32,
+    uniforms: Vec<Uniform<'static>>,
+    kind: Kind,
+}
+
+impl SharedPixelShaderElement {
+    pub(crate) fn new(
+        shader: GlesPixelProgram,
+        area: Rectangle<i32, Logical>,
+        opaque: Option<Vec<Rectangle<i32, Logical>>>,
+        alpha: f32,
+        uniforms: Vec<Uniform<'static>>,
+        kind: Kind,
+    ) -> Self {
+        Self {
+            shader,
+            state: Arc::new(ShaderState {
+                id: Id::new(),
+                commit: CommitCounter::default(),
+                area,
+                opaque: opaque.unwrap_or_default(),
+                alpha,
+                uniforms,
+                kind,
+            }),
+        }
+    }
+
+    pub(crate) fn resize(&mut self, area: Rectangle<i32, Logical>, opaque: Option<Vec<Rectangle<i32, Logical>>>) {
+        let opaque = opaque.unwrap_or_default();
+
+        if self.state.area != area || self.state.opaque != opaque {
+            let state = Arc::make_mut(&mut self.state);
+            state.area = area;
+            state.opaque = opaque;
+            state.commit.increment();
+        }
+    }
+
+    pub(crate) fn update_uniforms(&mut self, uniforms: Vec<Uniform<'static>>) {
+        let state = Arc::make_mut(&mut self.state);
+        state.uniforms = uniforms;
+        state.commit.increment();
+    }
+}
+
+impl Element for SharedPixelShaderElement {
+    fn id(&self) -> &Id {
+        &self.state.id
+    }
+
+    fn current_commit(&self) -> CommitCounter {
+        self.state.commit
+    }
+
+    fn src(&self) -> Rectangle<f64, Buffer> {
+        Rectangle::from_size(self.state.area.size.to_f64().to_buffer(1.0, Transform::Normal))
+    }
+
+    fn geometry(&self, scale: Scale<f64>) -> Rectangle<i32, Physical> {
+        self.state.area.to_physical_precise_round(scale)
+    }
+
+    fn opaque_regions(&self, scale: Scale<f64>) -> OpaqueRegions<i32, Physical> {
+        self.state
+            .opaque
+            .iter()
+            .map(|region| region.to_physical_precise_round(scale))
+            .collect()
+    }
+
+    fn alpha(&self) -> f32 {
+        self.state.alpha
+    }
+
+    fn kind(&self) -> Kind {
+        self.state.kind
+    }
+}
+
+impl RenderElement<GlesRenderer> for SharedPixelShaderElement {
+    fn draw(
+        &self,
+        frame: &mut GlesFrame<'_, '_>,
+        src: Rectangle<f64, Buffer>,
+        dst: Rectangle<i32, Physical>,
+        damage: &[Rectangle<i32, Physical>],
+        _opaque: &[Rectangle<i32, Physical>],
+    ) -> Result<(), GlesError> {
+        frame.render_pixel_shader_to(
+            &self.shader,
+            src,
+            dst,
+            self.state.area.size.to_buffer(1, Transform::Normal),
+            Some(damage),
+            self.state.alpha,
+            &self.state.uniforms,
+        )
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use std::borrow::Cow;
+
+    use smithay::backend::allocator::Fourcc;
+    use smithay::backend::egl::{EGLContext, EGLDevice, EGLDisplay};
+    use smithay::backend::renderer::gles::element::PixelShaderElement;
+    use smithay::backend::renderer::gles::{GlesTexture, UniformName, UniformType};
+    use smithay::backend::renderer::{Bind, Color32F, ExportMem, Frame, Offscreen, Renderer};
+
+    use super::*;
+
+    fn pixels(renderer: &mut GlesRenderer, element: &impl RenderElement<GlesRenderer>) -> Vec<u8> {
+        let size = (32, 32).into();
+        let mut texture: GlesTexture = renderer.create_buffer(Fourcc::Abgr8888, size).unwrap();
+        let rect = Rectangle::from_size((32, 32).into());
+        let mut target = renderer.bind(&mut texture).unwrap();
+
+        {
+            let mut frame = renderer
+                .render(&mut target, (32, 32).into(), Transform::Normal)
+                .unwrap();
+            frame.clear(Color32F::TRANSPARENT, &[rect]).unwrap();
+            element.draw(&mut frame, element.src(), rect, &[rect], &[]).unwrap();
+            let _ = frame.finish().unwrap();
+        }
+
+        let mapping = renderer
+            .copy_framebuffer(&target, Rectangle::from_size(size), Fourcc::Abgr8888)
+            .unwrap();
+        renderer.map_texture(&mapping).unwrap().to_vec()
+    }
+
+    #[test]
+    #[ignore = "requires an EGL rendering device"]
+    fn shared_shader_matches_smithay_and_keeps_old_frames_immutable() {
+        let device = EGLDevice::enumerate().unwrap().last().expect("an EGL device");
+        let display = unsafe { EGLDisplay::new(device).unwrap() };
+        let mut renderer = unsafe { GlesRenderer::new(EGLContext::new(&display).unwrap()).unwrap() };
+        let program = renderer
+            .compile_custom_pixel_shader(
+                super::super::corner_shader(super::super::ROUNDED_SOLID_SHADER),
+                &[
+                    UniformName::new("clip_rect", UniformType::_4f),
+                    UniformName::new("radius", UniformType::_1f),
+                    UniformName::new("color", UniformType::_4f),
+                ],
+            )
+            .unwrap();
+        let area = Rectangle::new((2, 3).into(), (32, 32).into());
+        let uniforms = |color| {
+            vec![
+                Uniform::new("clip_rect", [0.0_f32, 0.0, 32.0, 32.0]),
+                Uniform::new("radius", 8.0_f32),
+                Uniform::new("color", color),
+            ]
+        };
+        let red = [0.5_f32, 0.0, 0.0, 0.5];
+        let green = [0.0_f32, 0.5, 0.0, 0.5];
+        let opaque = Some(vec![Rectangle::from_size((20, 20).into())]);
+        let baseline = PixelShaderElement::new(
+            program.clone(),
+            area,
+            opaque.clone(),
+            0.5,
+            uniforms(red),
+            Kind::Unspecified,
+        );
+        let mut shared = SharedPixelShaderElement::new(program, area, opaque, 0.5, uniforms(red), Kind::Unspecified);
+        let old = shared.clone();
+        let old_commit = old.current_commit();
+
+        assert!(Arc::ptr_eq(&shared.state, &old.state));
+        assert!(
+            shared
+                .state
+                .uniforms
+                .iter()
+                .all(|uniform| matches!(uniform.name, Cow::Borrowed(_)))
+        );
+
+        for scale in [1.0, 1.25, 2.0] {
+            assert_eq!(shared.geometry(scale.into()), baseline.geometry(scale.into()));
+            assert_eq!(
+                &*shared.opaque_regions(scale.into()),
+                &*baseline.opaque_regions(scale.into())
+            );
+        }
+
+        assert_eq!(pixels(&mut renderer, &shared), pixels(&mut renderer, &baseline));
+        shared.resize(area, Some(vec![Rectangle::from_size((20, 20).into())]));
+        assert!(Arc::ptr_eq(&shared.state, &old.state));
+        shared.update_uniforms(uniforms(green));
+        assert!(!Arc::ptr_eq(&shared.state, &old.state));
+        assert_eq!(shared.id(), old.id());
+        assert_eq!(old.current_commit(), old_commit);
+        assert_ne!(shared.current_commit(), old_commit);
+        assert_eq!(pixels(&mut renderer, &old), pixels(&mut renderer, &baseline));
+        assert_ne!(pixels(&mut renderer, &shared), pixels(&mut renderer, &baseline));
+
+        let retained = shared.clone();
+        shared.resize(Rectangle::from_size((16, 16).into()), None);
+        assert_eq!(retained.geometry(1.0.into()), area.to_physical_precise_round(1.0));
+        assert_eq!(shared.geometry(1.0.into()).size, (16, 16).into());
+        assert!(shared.opaque_regions(1.0.into()).is_empty());
+        assert_eq!(shared.alpha(), baseline.alpha());
+        assert_eq!(shared.kind(), baseline.kind());
+    }
+}

compositor/src/shell_control.rs

@@ -4,8 +4,6 @@ use ferese_protocols::shell::v1::server::ferese_shell_manager_v1::FereseShellMan
 use ferese_protocols::shell::v1::server::ferese_shell_v1::FereseShellV1;
 use ferese_protocols::shell::v1::server::{ferese_shell_manager_v1, ferese_shell_v1};
 use smithay::reexports::wayland_server::{Client, DataInit, Dispatch, DisplayHandle, GlobalDispatch, New, Resource};
-use smithay::wayland::compositor::with_states;
-use smithay::wayland::shell::xdg::XdgToplevelSurfaceData;
 
 use crate::Ferese;
 use crate::private_client::ClientCapabilities;
@@ -270,10 +268,15 @@ impl Ferese {
             self.last_shell_snapshot = None;
             return;
         }
-        let snapshot = self.shell_snapshot();
-        if self.last_shell_snapshot.as_ref() == Some(&snapshot) {
+        if self
+            .last_shell_snapshot
+            .as_ref()
+            .is_some_and(|snapshot| self.shell_snapshot_matches(snapshot))
+        {
             return;
         }
+
+        let snapshot = self.shell_snapshot();
         for resource in &self.shell_resources {
             if let Ok(shell) = resource.upgrade() {
                 self.shell_snapshot_serial = self.shell_snapshot_serial.wrapping_add(1);
@@ -283,6 +286,65 @@ impl Ferese {
         self.last_shell_snapshot = Some(snapshot);
     }
 
+    fn shell_snapshot_matches(&self, snapshot: &ShellSnapshot) -> bool {
+        let mut outputs = self.output_workspaces.connected_outputs();
+
+        for previous in &snapshot.outputs {
+            if outputs.next() != Some(previous.id)
+                || self.output_names.get(&previous.id) != Some(&previous.name)
+                || self.output_workspaces.active_workspace(previous.id) != Some(previous.active_workspace)
+                || (self.output_workspaces.focused_output() == Some(previous.id)) != previous.focused
+            {
+                return false;
+            }
+        }
+
+        if outputs.next().is_some() {
+            return false;
+        }
+
+        let mut workspaces = self.output_workspaces.workspace_views_iter(&self.workspaces);
+
+        for previous in &snapshot.workspaces {
+            let Some(view) = workspaces.next() else {
+                return false;
+            };
+
+            if previous.id != view.id
+                || previous.output != Some(view.output)
+                || previous.index != view.index
+                || previous.window_count != view.window_count as u32
+                || previous.visible != view.visible
+                || previous.focused != view.focused
+            {
+                return false;
+            }
+        }
+
+        if workspaces.next().is_some() {
+            return false;
+        }
+
+        let mut windows = self.windows.ordered_ids().filter_map(|id| self.shell_window_data(id));
+
+        for previous in &snapshot.windows {
+            let Some((id, workspace, app_id, title, state)) = windows.next() else {
+                return false;
+            };
+
+            if previous.id != id
+                || previous.workspace != workspace
+                || previous.app_id != app_id
+                || previous.title != title
+                || previous.state != state
+            {
+                return false;
+            }
+        }
+
+        windows.next().is_none()
+    }
+
     fn shell_snapshot(&self) -> ShellSnapshot {
         ShellSnapshot {
             outputs: self.output_snapshots(),
@@ -319,8 +381,7 @@ impl Ferese {
 
     fn workspace_snapshots(&self) -> Vec<WorkspaceSnapshot> {
         self.output_workspaces
-            .workspace_views(&self.workspaces)
-            .into_iter()
+            .workspace_views_iter(&self.workspaces)
             .map(|view| WorkspaceSnapshot {
                 id: view.id,
                 output: Some(view.output),
@@ -333,56 +394,46 @@ impl Ferese {
             .collect()
     }
 
+    fn shell_window_data(&self, id: WindowId) -> Option<(WindowId, u64, &str, &str, ferese_shell_v1::WindowState)> {
+        let workspace = self.workspaces.workspace_for_window(id)?;
+        let record = self.windows.record(id)?;
+        self.windows.window(id)?.toplevel()?;
+        let mut state = ferese_shell_v1::WindowState::empty();
+
+        if self.focused_window == Some(id) {
+            state |= ferese_shell_v1::WindowState::Focused;
+        }
+
+        if self
+            .workspaces
+            .workspace(workspace)
+            .is_some_and(|workspace| workspace.fullscreen == Some(id))
+        {
+            state |= ferese_shell_v1::WindowState::Fullscreen;
+        }
+
+        if matches!(
+            self.workspaces.placement(id),
+            Some(ferese_core::WindowPlacement::Floating { .. })
+        ) {
+            state |= ferese_shell_v1::WindowState::Floating;
+        }
+
+        Some((id, workspace.0, &record.app_id, &record.title, state))
+    }
+
     fn managed_window_snapshots(&self) -> Vec<ManagedWindowSnapshot> {
-        let mut snapshots = self
-            .windows
-            .ids()
-            .iter()
-            .filter_map(|(window, id)| {
-                let workspace = self.workspaces.workspace_for_window(*id)?.0;
-                let toplevel = window.toplevel()?;
-                let (app_id, title) = with_states(toplevel.wl_surface(), |states| {
-                    let attributes = states
-                        .data_map
-                        .get::<XdgToplevelSurfaceData>()
-                        .expect("xdg toplevel state exists")
-                        .lock()
-                        .expect("xdg toplevel state is not poisoned");
-
-                    (
-                        attributes.app_id.clone().unwrap_or_default(),
-                        attributes.title.clone().unwrap_or_default(),
-                    )
-                });
-                let mut state = ferese_shell_v1::WindowState::empty();
-
-                if self.focused_window == Some(*id) {
-                    state |= ferese_shell_v1::WindowState::Focused;
-                }
-                if self
-                    .workspaces
-                    .workspace_for_window(*id)
-                    .and_then(|workspace| self.workspaces.workspace(workspace))
-                    .is_some_and(|workspace| workspace.fullscreen == Some(*id))
-                {
-                    state |= ferese_shell_v1::WindowState::Fullscreen;
-                }
-                if self.is_floating_window(window) {
-                    state |= ferese_shell_v1::WindowState::Floating;
-                }
-
-                Some(ManagedWindowSnapshot {
-                    id: *id,
-                    workspace,
-                    app_id,
-                    title,
-                    state,
-                })
+        self.windows
+            .ordered_ids()
+            .filter_map(|id| self.shell_window_data(id))
+            .map(|(id, workspace, app_id, title, state)| ManagedWindowSnapshot {
+                id,
+                workspace,
+                app_id: app_id.to_owned(),
+                title: title.to_owned(),
+                state,
             })
-            .collect::<Vec<_>>();
-
-        snapshots.sort_by_key(|snapshot| snapshot.id.0);
-        snapshots
+            .collect()
     }
 
     fn handle_shell_window_request(
@@ -530,6 +581,66 @@ fn send_request_failed(shell: &FereseShellV1, request: ferese_shell_v1::FailedRe
 
 #[cfg(test)]
 mod tests {
+    #[test]
+    #[ignore = "requires a private XDG_RUNTIME_DIR and permission to bind test sockets"]
+    fn snapshot_precheck_detects_membership_selection_and_output_changes() {
+        use smithay::output::{Output, PhysicalProperties, Subpixel};
+        use smithay::reexports::calloop::EventLoop;
+        use smithay::reexports::wayland_server::Display;
+
+        use super::*;
+
+        let runtime = std::path::PathBuf::from(std::env::var_os("XDG_RUNTIME_DIR").unwrap());
+        assert!(runtime.starts_with(std::env::temp_dir()));
+        let mut event_loop = EventLoop::try_new().unwrap();
+        let config = crate::config::Config::default().runtime_config().unwrap();
+        let mut state = Ferese::new(&mut event_loop, Display::new().unwrap(), config).unwrap();
+        let output = Output::new(
+            "snapshot-test".into(),
+            PhysicalProperties {
+                size: (0, 0).into(),
+                subpixel: Subpixel::Unknown,
+                make: "test".into(),
+                model: "test".into(),
+            },
+        );
+        output.change_current_state(
+            Some(smithay::output::Mode {
+                size: (800, 600).into(),
+                refresh: 60_000,
+            }),
+            Some(smithay::utils::Transform::Normal),
+            None,
+            Some((0, 0).into()),
+        );
+        state.space.map_output(&output, (0, 0));
+        state.register_output(&output, "snapshot-test".into());
+        let original = state.shell_snapshot();
+
+        for _ in 0..100 {
+            assert!(state.shell_snapshot_matches(&original));
+        }
+
+        state
+            .workspaces
+            .insert_window(WindowId(99), ferese_layout::Axis::Horizontal, 0.5)
+            .unwrap();
+        assert!(!state.shell_snapshot_matches(&original));
+        let occupied = state.shell_snapshot();
+        assert!(state.shell_snapshot_matches(&occupied));
+        let output_id = state.output_ids[&output];
+        let next = state.workspaces.create_workspace();
+        state.output_workspaces.assign_workspace(output_id, next).unwrap();
+        assert!(!state.shell_snapshot_matches(&occupied));
+        let assigned = state.shell_snapshot();
+        state.output_workspaces.switch_workspace(output_id, next).unwrap();
+        assert!(!state.shell_snapshot_matches(&assigned));
+        let selected = state.shell_snapshot();
+        assert!(state.shell_snapshot_matches(&selected));
+        state.unregister_output(&output);
+        assert!(!state.shell_snapshot_matches(&selected));
+    }
+
     #[test]
     fn logout_serial_cannot_authorize_a_different_session_query() {
         assert!(super::logout_confirmation_matches(Some(42), Some(9), 42, 9));

compositor/src/stacking.rs

@@ -21,6 +21,7 @@ pub(crate) fn layer_priority(floating: bool, zooming: bool, fullscreen: bool, ab
 pub(crate) struct WindowStack {
     order: Vec<WindowId>,
     ranks: HashMap<WindowId, usize>,
+    revision: u64,
 }
 
 impl WindowStack {
@@ -28,12 +29,14 @@ impl WindowStack {
         if let std::collections::hash_map::Entry::Vacant(entry) = self.ranks.entry(id) {
             entry.insert(self.order.len());
             self.order.push(id);
+            self.revision = self.revision.wrapping_add(1);
         }
     }
 
     pub fn remove(&mut self, id: WindowId) {
         if let Some(rank) = self.ranks.remove(&id) {
             self.order.remove(rank);
+            self.revision = self.revision.wrapping_add(1);
             for (rank, candidate) in self.order.iter().enumerate().skip(rank) {
                 self.ranks.insert(*candidate, rank);
             }
@@ -41,6 +44,10 @@ impl WindowStack {
     }
 
     pub fn raise(&mut self, id: WindowId) {
+        if self.order.last() == Some(&id) {
+            return;
+        }
+
         self.remove(id);
         self.insert(id);
     }
@@ -48,12 +55,113 @@ impl WindowStack {
     pub fn rank(&self, id: WindowId) -> usize {
         self.ranks.get(&id).copied().unwrap_or(usize::MAX)
     }
+
+    pub fn revision(&self) -> u64 {
+        self.revision
+    }
+}
+
+/// Desired order survives coordinate-only remaps, which Smithay also raises.
+pub(crate) struct StackingCache<W> {
+    order: Vec<W>,
+    revision: Option<u64>,
+    dirty: bool,
+    remapped: bool,
+}
+
+impl<W> Default for StackingCache<W> {
+    fn default() -> Self {
+        Self {
+            order: Vec::new(),
+            revision: None,
+            dirty: true,
+            remapped: true,
+        }
+    }
+}
+
+impl<W> StackingCache<W> {
+    pub fn invalidate(&mut self) {
+        self.dirty = true;
+    }
+
+    pub fn remapped(&mut self) {
+        self.remapped = true;
+    }
+
+    pub fn needs_rebuild(&self, revision: u64, mapped: usize) -> bool {
+        self.dirty || self.revision != Some(revision) || self.order.len() != mapped
+    }
+
+    pub fn needs_restore(&self) -> bool {
+        self.remapped
+    }
+
+    pub fn replace(&mut self, order: Vec<W>, revision: u64) {
+        self.order = order;
+        self.revision = Some(revision);
+        self.dirty = false;
+        self.remapped = true;
+    }
+
+    pub fn order(&self) -> &[W] {
+        &self.order
+    }
+
+    pub fn restored(&mut self) {
+        self.remapped = false;
+    }
 }
 
 #[cfg(test)]
 mod tests {
     use super::*;
 
+    #[test]
+    fn clean_stacking_and_coordinate_remaps_do_not_require_resorting() {
+        let mut cache = StackingCache::default();
+        assert!(cache.needs_rebuild(1, 2));
+        cache.replace(vec!["first", "second"], 1);
+        cache.restored();
+        let storage = cache.order().as_ptr();
+
+        for _ in 0..100 {
+            assert!(!cache.needs_rebuild(1, 2));
+            assert!(!cache.needs_restore());
+            assert_eq!(cache.order().as_ptr(), storage);
+        }
+
+        cache.remapped();
+        assert!(!cache.needs_rebuild(1, 2));
+        assert!(cache.needs_restore());
+        assert_eq!(cache.order(), ["first", "second"]);
+        cache.restored();
+        assert!(cache.needs_rebuild(2, 2));
+        assert!(cache.needs_rebuild(1, 1));
+        cache.invalidate();
+        assert!(cache.needs_rebuild(1, 2));
+    }
+
+    #[test]
+    fn stack_revision_changes_only_when_membership_or_rank_changes() {
+        let mut stack = WindowStack::default();
+        stack.insert(WindowId(1));
+        let first = stack.revision();
+        stack.insert(WindowId(1));
+        stack.raise(WindowId(1));
+        stack.remove(WindowId(9));
+        assert_eq!(stack.revision(), first);
+
+        stack.insert(WindowId(2));
+        let second = stack.revision();
+        assert_ne!(second, first);
+        stack.raise(WindowId(1));
+        assert_ne!(stack.revision(), second);
+        let raised = stack.revision();
+        stack.remove(WindowId(1));
+        assert_ne!(stack.revision(), raised);
+    }
+
     #[test]
     fn cached_ranks_match_reference_order_after_mixed_operations() {
         let mut stack = WindowStack::default();

compositor/src/state.rs

@@ -76,7 +76,7 @@ use smithay::wayland::xdg_toplevel_icon::XdgToplevelIconManager;
 use window_registry::WindowRegistry;
 
 use crate::backends::direct::DirectBackendState;
-use crate::config::{Binding, DaemonConfig, InputSettings, OutputProfile, ThemeSettings};
+use crate::config::{Binding, BindingSet, DaemonConfig, InputSettings, OutputProfile, ThemeSettings};
 use crate::cursor::{NamedCursor, cursor_theme, load_named_cursor};
 use crate::dimming::DimAnimation;
 use crate::gestures::{Swipe, SwipeDirection};
@@ -91,7 +91,7 @@ use crate::portal_session::PortalSession;
 use crate::portal_shortcuts::PortalShortcuts;
 use crate::session_lock::{IdleSettings, Lock};
 use crate::shell_control::ShellSnapshot;
-use crate::stacking::WindowStack;
+use crate::stacking::{StackingCache, WindowStack};
 use crate::wallpaper::{WallpaperConfig, WallpaperState};
 use crate::window_rules::{WindowRule, resolve as resolve_window_rules};
 use crate::winit::NestedBackend;
@@ -228,8 +228,13 @@ impl WorkspaceSlide {
     }
 
     fn progress(&self) -> f64 {
+        self.progress_at(Duration::ZERO)
+    }
+
+    fn progress_at(&self, delta: Duration) -> f64 {
         self.held_progress.unwrap_or_else(|| {
-            smoothstep((self.elapsed.as_secs_f64() / WORKSPACE_SLIDE_DURATION.as_secs_f64()).min(1.0))
+            let elapsed = self.elapsed.saturating_add(delta).min(WORKSPACE_SLIDE_DURATION);
+            smoothstep(elapsed.as_secs_f64() / WORKSPACE_SLIDE_DURATION.as_secs_f64())
         })
     }
 
@@ -260,6 +265,7 @@ impl WorkspaceSlide {
         self.items.iter().any(|item| item.workspace == workspace)
     }
 
+    #[cfg(test)]
     fn offset(&self, workspace: WorkspaceId, width: f64, height: f64) -> (f64, f64) {
         let progress = self.progress();
         let position = self
@@ -323,12 +329,15 @@ pub struct Ferese {
     pub workspaces: WorkspaceSet,
     pub output_workspaces: OutputWorkspaceMap,
     pub(crate) output_ids: HashMap<Output, OutputId>,
+    outputs_by_id: HashMap<OutputId, Output>,
+    pub(crate) output_names: HashMap<OutputId, String>,
     output_identity_ids: HashMap<String, OutputId>,
     pub(crate) windows: WindowRegistry<Window>,
     pub(crate) render: crate::render::RenderResources,
     pub(crate) nested_backend: Option<NestedBackend>,
     pub(crate) wallpaper: WallpaperState,
     window_stack: WindowStack,
+    stacking_cache: StackingCache<Window>,
     floating_above_fullscreen: HashMap<WindowId, WindowId>,
     floating_memory: crate::floating::Memory,
     floating_save_worker: crate::floating::SaveWorker,
@@ -341,13 +350,14 @@ pub struct Ferese {
     viewport_animations: HashMap<WorkspaceId, AnimatedValue>,
     focus_swipe: Option<FocusSwipe>,
     workspace_slides: HashMap<OutputId, WorkspaceSlide>,
+    workspace_slide_offsets: HashMap<WorkspaceId, (f64, f64)>,
     pub focused_window: Option<WindowId>,
     pub(crate) focus_history: ferese_core::FocusHistory,
     pub(crate) focus_cycle: Option<ferese_core::FocusCycle>,
     column_width_presets: Vec<ColumnWidth>,
     gap_config: GapConfig,
     pub(crate) input_settings: InputSettings,
-    pub(crate) bindings: Vec<Binding>,
+    pub(crate) bindings: BindingSet,
     workspace_auto_back_and_forth: bool,
     window_rules: Vec<WindowRule>,
     pub(crate) theme_settings: ThemeSettings,
@@ -543,12 +553,15 @@ impl Ferese {
             ),
             output_workspaces: OutputWorkspaceMap::default(),
             output_ids: HashMap::new(),
+            outputs_by_id: HashMap::new(),
+            output_names: HashMap::new(),
             output_identity_ids: HashMap::new(),
             windows: WindowRegistry::default(),
             render: Default::default(),
             nested_backend: None,
             wallpaper: WallpaperState::with_wakeup(config.wallpaper, Some(event_loop.get_signal())),
             window_stack: WindowStack::default(),
+            stacking_cache: StackingCache::default(),
             floating_above_fullscreen: HashMap::new(),
             floating_memory: crate::floating::Memory::path()
                 .map(|p| crate::floating::Memory::load(&p))
@@ -563,13 +576,14 @@ impl Ferese {
             viewport_animations: HashMap::new(),
             focus_swipe: None,
             workspace_slides: HashMap::new(),
+            workspace_slide_offsets: HashMap::new(),
             focused_window: None,
             focus_history: Default::default(),
             focus_cycle: None,
             column_width_presets: config.column_width_presets,
             gap_config: config.gap_config,
             input_settings: config.input_settings,
-            bindings: config.bindings,
+            bindings: config.bindings.into(),
             workspace_auto_back_and_forth: config.workspace_auto_back_and_forth,
             window_rules: config.window_rules,
             theme_settings: config.theme_settings,
@@ -707,7 +721,7 @@ impl Ferese {
             .map_err(|error| error.to_string())?;
         self.gap_config = config.gap_config;
         self.input_settings = config.input_settings;
-        self.bindings = config.bindings;
+        self.bindings = config.bindings.into();
         self.workspace_auto_back_and_forth = config.workspace_auto_back_and_forth;
         self.portal_shortcuts.reconcile(&self.bindings, &self.input_settings);
         let old_rules = std::mem::replace(&mut self.window_rules, config.window_rules);
@@ -717,6 +731,7 @@ impl Ferese {
         self.animations_enabled = config.animations_enabled;
         if !self.animations_enabled {
             self.workspace_slides.clear();
+            self.workspace_slide_offsets.clear();
         }
         self.animation_speed = config.animation_speed;
         self.spring_config = config.spring_config;
@@ -976,6 +991,22 @@ impl ClientData for ClientState {
 
 #[cfg(test)]
 mod tests {
+    #[test]
+    fn sampling_slide_progress_matches_advancing_without_mutating_the_slide() {
+        let slide = WorkspaceSlide::new(None, WorkspaceId(1), WorkspaceId(2), SwipeDirection::Left);
+
+        for delta in [Duration::ZERO, Duration::from_millis(8), Duration::from_secs(1)] {
+            let mut advanced = slide.clone();
+            advanced.advance(delta);
+            assert_eq!(slide.progress_at(delta), advanced.progress());
+            assert_eq!(slide.elapsed, WORKSPACE_SLIDE_FIRST_FRAME);
+        }
+
+        let mut held = slide;
+        held.held_progress = Some(0.37);
+        assert_eq!(held.progress_at(Duration::from_secs(1)), 0.37);
+    }
+
     #[test]
     fn configured_motion_policy_scales_durations_and_reduced_motion_wins() {
         for (source, milliseconds) in [

compositor/src/state/animation.rs

@@ -20,7 +20,56 @@ impl Ferese {
         self.last_animation_tick = Instant::now();
     }
 
+    fn animations_need_tick(&self) -> bool {
+        if self.focus_swipe.is_some()
+            || !self.workspace_slides.is_empty()
+            || !self.dismissing_popups.is_empty()
+            || self.render.snapshots().next().is_some()
+            || self.overview.needs_tick()
+        {
+            return true;
+        }
+
+        let moving = |value: &AnimatedValue| value.current != value.target || value.velocity != 0.0;
+
+        if self.viewport_animations.iter().any(|(workspace, viewport)| {
+            self.output_workspaces
+                .output_for_workspace(*workspace)
+                .is_some_and(|output| self.output_workspaces.active_workspace(output) == Some(*workspace))
+                && moving(viewport)
+        }) {
+            return true;
+        }
+
+        let selected = if self.overview.is_active() {
+            self.overview.selected()
+        } else {
+            self.focused_window
+        };
+
+        self.windows.records().any(|(&id, record)| {
+            let focus = if selected == Some(id) { 1.0 } else { 0.0 };
+            let dim = crate::dimming::target(
+                self.inactive_dim,
+                self.focused_window,
+                id,
+                self.overview.is_presenting(),
+            );
+
+            record_needs_tick(record, focus, dim, || {
+                self.windows
+                    .window(id)
+                    .is_some_and(|window| self.space.element_location(window).is_some())
+            })
+        })
+    }
+
     pub(super) fn advance_animations_by(&mut self, delta: std::time::Duration) -> bool {
+        if !self.animations_need_tick() {
+            self.sync_window_stacking();
+            return false;
+        }
+
         let delta = delta.mul_f64(self.animation_speed);
         if self
             .focus_swipe
@@ -30,21 +79,6 @@ impl Ferese {
             self.focus_swipe = None;
         }
 
-        let visible_workspaces = if self.viewport_animations.is_empty() {
-            HashSet::new()
-        } else {
-            self.space
-                .outputs()
-                .filter_map(|output| self.output_ids.get(output))
-                .filter_map(|output| self.output_workspaces.active_workspace(*output))
-                .collect::<HashSet<_>>()
-        };
-
-        let windows = self
-            .space
-            .elements()
-            .filter_map(|window| self.windows.ids().get(window).copied().map(|id| (window.clone(), id)))
-            .collect::<Vec<_>>();
         let mut active_animation = false;
         let mut completed_slides = Vec::new();
         for (output, slide) in &mut self.workspace_slides {
@@ -102,9 +136,12 @@ impl Ferese {
             dim_changed |= previous != focus.current;
         }
 
-        for (_, id) in &windows {
-            let target = crate::dimming::target(dim_settings, self.focused_window, *id, self.overview.is_presenting());
-            let Some(record) = self.windows.record_mut(*id) else {
+        for window in self.space.elements() {
+            let Some(id) = self.windows.ids().get(window).copied() else {
+                continue;
+            };
+            let target = crate::dimming::target(dim_settings, self.focused_window, id, self.overview.is_presenting());
+            let Some(record) = self.windows.record_mut(id) else {
                 continue;
             };
 
@@ -184,7 +221,11 @@ impl Ferese {
         // Keep scheduling frames while waiting, so the deadline cannot stall.
         active_animation |= !blocked_workspaces.is_empty();
         for (workspace, viewport) in &mut self.viewport_animations {
-            if !visible_workspaces.contains(workspace) {
+            if !self
+                .output_workspaces
+                .output_for_workspace(*workspace)
+                .is_some_and(|output| self.output_workspaces.active_workspace(output) == Some(*workspace))
+            {
                 continue;
             }
 
@@ -202,8 +243,13 @@ impl Ferese {
             }
         }
 
-        let mut settled_coupled_widths = Vec::new();
-        for (window, id) in windows {
+        let mut remaps = Vec::new();
+
+        for window in self.space.elements() {
+            let Some(id) = self.windows.ids().get(window).copied() else {
+                continue;
+            };
+
             if self
                 .workspaces
                 .workspace_for_window(id)
@@ -229,6 +275,11 @@ impl Ferese {
                 geometry.visual.velocity.width = 0.0;
             }
             active_animation |= geometry.advance(delta, self.spring_config, self.animations_enabled);
+
+            if zooming != geometry.is_zooming() {
+                self.stacking_cache.invalidate();
+            }
+
             if let Some(target) = coupled_target {
                 geometry.visual.target.width = target;
             }
@@ -262,7 +313,7 @@ impl Ferese {
                 geometry.visual.current.width = width.current;
                 geometry.visual.velocity.width = width.velocity;
                 if !width_active {
-                    settled_coupled_widths.push(id);
+                    record.coupled_width = None;
                 }
             }
 
@@ -287,12 +338,18 @@ impl Ferese {
             }
 
             let visual = geometry.visual.current;
-            self.space
-                .map_element(window, (visual.x.round() as i32, visual.y.round() as i32), false);
+            let location = (visual.x.round() as i32, visual.y.round() as i32).into();
+
+            if self.space.element_location(window) != Some(location) {
+                remaps.push((id, location));
+            }
         }
 
-        for id in settled_coupled_widths {
-            self.windows.update(id, |record| record.coupled_width = None);
+        for (id, location) in remaps {
+            if let Some(window) = self.windows.window(id) {
+                self.space.map_element(window.clone(), location, false);
+                self.stacking_cache.remapped();
+            }
         }
 
         if !completed_slides.is_empty() {
@@ -320,6 +377,7 @@ impl Ferese {
         active_animation |= self
             .overview
             .advance(delta, self.spring_config, self.animations_enabled);
+        self.refresh_workspace_slide_offsets();
         self.sync_window_stacking();
 
         if active_animation || dim_changed {
@@ -337,48 +395,173 @@ impl Ferese {
     }
 
     pub(crate) fn workspace_slide_offset(&self, window: WindowId) -> (f64, f64) {
-        self.workspace_slide_offset_at(window, Duration::ZERO)
+        self.workspaces
+            .workspace_for_window(window)
+            .and_then(|workspace| self.workspace_slide_offsets.get(&workspace).copied())
+            .unwrap_or_default()
     }
 
-    pub(super) fn workspace_slide_offset_at(&self, window: WindowId, delta: Duration) -> (f64, f64) {
-        let Some(workspace) = self.workspaces.workspace_for_window(window) else {
-            return (0.0, 0.0);
-        };
+    pub(super) fn sample_workspace_slide_offsets(
+        &self,
+        output: Option<OutputId>,
+        delta: Duration,
+    ) -> HashMap<WorkspaceId, (f64, f64)> {
+        let mut offsets = HashMap::new();
+        self.fill_workspace_slide_offsets(output, delta, &mut offsets);
+        offsets
+    }
 
-        let Some(output_id) = self
-            .workspace_slides
-            .iter()
-            .find_map(|(output, slide)| slide.contains(workspace).then_some(*output))
-            .or_else(|| self.output_workspaces.output_for_workspace(workspace))
-        else {
-            return (0.0, 0.0);
-        };
+    pub(super) fn refresh_workspace_slide_offsets(&mut self) {
+        // Reuse the input snapshot's allocation. Predicted render snapshots
+        // remain separate and never change hit-testing or gesture state.
+        let mut offsets = std::mem::take(&mut self.workspace_slide_offsets);
+        offsets.clear();
+        self.fill_workspace_slide_offsets(None, Duration::ZERO, &mut offsets);
+        self.workspace_slide_offsets = offsets;
+    }
 
-        let Some(slide) = self.workspace_slides.get(&output_id) else {
-            return (0.0, 0.0);
-        };
+    fn fill_workspace_slide_offsets(
+        &self,
+        output: Option<OutputId>,
+        delta: Duration,
+        offsets: &mut HashMap<WorkspaceId, (f64, f64)>,
+    ) {
+        for (output_id, slide) in &self.workspace_slides {
+            if output.is_some_and(|output| output != *output_id) {
+                continue;
+            }
 
-        let Some(size) = self
-            .output_ids
-            .iter()
-            .find(|(_, id)| **id == output_id)
-            .and_then(|(output, _)| self.space.output_geometry(output))
-            .map(|geometry| geometry.size)
-        else {
-            return (0.0, 0.0);
-        };
+            let Some(size) = self
+                .outputs_by_id
+                .get(output_id)
+                .and_then(|output| self.space.output_geometry(output))
+                .map(|geometry| geometry.size)
+            else {
+                continue;
+            };
+            let progress = slide.progress_at(delta);
 
-        let mut slide = slide.clone();
-        if slide.held_progress.is_none() && !delta.is_zero() {
-            slide.advance(delta);
+            for item in &slide.items {
+                let position = item.start.between(item.target, progress);
+                offsets.insert(
+                    item.workspace,
+                    (position.x * f64::from(size.w), position.y * f64::from(size.h)),
+                );
+            }
         }
-
-        slide.offset(workspace, f64::from(size.w), f64::from(size.h))
     }
 
     pub(crate) fn cancel_workspace_slides(&mut self) -> bool {
         let active = !self.workspace_slides.is_empty();
         self.workspace_slides.clear();
+        self.workspace_slide_offsets.clear();
         active
     }
 }
+
+// Inspect current targets, not the previous frame's activity. Target changes
+// and client waits must wake a desktop that was settled on its last tick.
+fn record_needs_tick(
+    record: &super::window_registry::WindowRecord,
+    focus: f64,
+    dim: f64,
+    mapped: impl FnOnce() -> bool,
+) -> bool {
+    if record.resize.is_some()
+        || record.closing.as_ref().is_some_and(|close| !close.close_sent)
+        || record.focus.as_ref().is_none_or(|motion| motion.needs_update(focus))
+    {
+        return true;
+    }
+
+    let moving = |value: &AnimatedValue| value.current != value.target || value.velocity != 0.0;
+    let pending = record.dimming.as_ref().is_none_or(|motion| motion.needs_update(dim))
+        || record.world_x.as_ref().is_some_and(|(_, world)| moving(world))
+        || record.coupled_width.is_some()
+        || record.geometry.is_some_and(|geometry| {
+            geometry.is_zooming()
+                || geometry.presentation_changed
+                || geometry.client.waiting_for_commit()
+                || geometry.visual.current != geometry.visual.target
+                || geometry.visual.velocity != ferese_animation::RectVelocity::default()
+                || (!record.natural_floating_pending
+                    && geometry.client.last_configured_size != Some(ClientSize::from_rect(geometry.logical)))
+        });
+
+    // Hidden geometry and dimming do not advance in the full path.
+    // A stale hidden target must not keep waking the whole desktop.
+    pending && mapped()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::super::window_registry::WindowRecord;
+    use super::*;
+
+    fn settled() -> WindowRecord {
+        let rect = Rect::new(0.0, 0.0, 400.0, 300.0);
+        let mut geometry = WindowGeometry::new(rect, Some(ClientSize::from_rect(rect)));
+        geometry.presentation_changed = false;
+
+        WindowRecord {
+            geometry: Some(geometry),
+            focus: Some(DimAnimation::new(1.0)),
+            dimming: Some(DimAnimation::new(0.0)),
+            ..Default::default()
+        }
+    }
+
+    #[test]
+    fn idle_check_skips_mapping_lookup_but_new_focus_and_dim_targets_wake_it() {
+        let record = settled();
+
+        for _ in 0..100 {
+            assert!(!record_needs_tick(&record, 1.0, 0.0, || panic!(
+                "settled record needs no mapping lookup"
+            )));
+        }
+
+        assert!(record_needs_tick(&record, 0.0, 0.0, || true));
+        assert!(record_needs_tick(&record, 1.0, 0.15, || true));
+        assert!(!record_needs_tick(&record, 1.0, 0.15, || false));
+    }
+
+    #[test]
+    fn geometry_motion_client_waits_and_resize_barriers_cannot_be_skipped() {
+        let mut record = settled();
+        record
+            .geometry
+            .as_mut()
+            .unwrap()
+            .visual
+            .set_target(Rect::new(10.0, 0.0, 400.0, 300.0));
+        assert!(record_needs_tick(&record, 1.0, 0.0, || true));
+        assert!(!record_needs_tick(&record, 1.0, 0.0, || false));
+
+        let mut record = settled();
+        record.geometry.as_mut().unwrap().client.request_size(
+            ClientSize {
+                width: 500,
+                height: 300,
+            },
+            Duration::ZERO,
+        );
+        assert!(record_needs_tick(&record, 1.0, 0.0, || true));
+        record.resize = Some(crate::resize_transaction::ResizeTransaction::new(
+            1.into(),
+            Duration::ZERO,
+        ));
+        assert!(record_needs_tick(&record, 1.0, 0.0, || false));
+    }
+
+    #[test]
+    fn close_requests_and_coupled_width_cleanup_still_get_their_final_tick() {
+        let mut record = settled();
+        record.closing = Some(ClosingAnimation::default());
+        assert!(record_needs_tick(&record, 1.0, 0.0, || false));
+        record.closing.as_mut().unwrap().close_sent = true;
+        assert!(!record_needs_tick(&record, 1.0, 0.0, || true));
+        record.coupled_width = Some((WorkspaceId(1), AnimatedValue::new(400.0)));
+        assert!(record_needs_tick(&record, 1.0, 0.0, || true));
+    }
+}

compositor/src/state/floating.rs

@@ -17,12 +17,7 @@ impl Ferese {
             Some(WindowPlacement::Floating { rect }) => rect,
             None => return,
         };
-        if let Some(handle) = self
-            .windows
-            .ids()
-            .iter()
-            .find_map(|(handle, id)| (*id == window).then_some(handle.clone()))
-        {
+        if let Some(handle) = self.windows.window(window).cloned() {
             if matches!(
                 self.workspaces.placement(window),
                 Some(WindowPlacement::Floating { .. })
@@ -178,6 +173,10 @@ impl Ferese {
             .geometry
             .get_or_insert_with(|| WindowGeometry::new(rect, client_size(window)));
 
+        if geometry.is_zooming() {
+            self.stacking_cache.invalidate();
+        }
+
         if let Some(size) = geometry.follow_pointer(rect, self.start_time.elapsed())
             && let Some(toplevel) = window.toplevel()
         {
@@ -188,7 +187,7 @@ impl Ferese {
         }
         self.windows.update(id, |record| record.world_x = None);
         self.windows.update(id, |record| record.coupled_width = None);
-        self.space.map_element(window.clone(), location, false);
+        self.map_window_geometry(window.clone(), location);
         self.sync_window_stacking();
         // Move/resize/cancel callbacks run with Smithay's pointer mutex held.
         // Cursor rendering reads current_location(), which would lock it again.
@@ -269,14 +268,7 @@ impl Ferese {
         let (app, parent) = Self::floating_metadata(window);
         let parent_rect = parent
             .as_ref()
-            .and_then(|surface| {
-                self.windows.ids().iter().find_map(|(window, id)| {
-                    window
-                        .toplevel()
-                        .is_some_and(|top| top.wl_surface() == surface)
-                        .then_some(*id)
-                })
-            })
+            .and_then(|surface| self.windows.id_for_surface(surface))
             .and_then(|parent| self.presented_window_rect(parent))
             .and_then(|rect| intersection(rect, work));
         let dialog = crate::window_rules::is_native_dialog(app.as_deref());
@@ -420,10 +412,9 @@ impl Ferese {
             .workspaces
             .workspace_for_window(window)
             .and_then(|workspace| self.output_workspaces.output_for_workspace(workspace));
-        self.output_ids
-            .iter()
-            .find(|(_, id)| Some(**id) == output_id)
-            .and_then(|(output, _)| self.output_bounds_for(output))
+        output_id
+            .and_then(|id| self.outputs_by_id.get(&id))
+            .and_then(|output| self.output_bounds_for(output))
             .or_else(|| self.output_bounds())
     }
 

compositor/src/state/focus.rs

@@ -49,7 +49,7 @@ impl Ferese {
         let available = self.focus_candidates();
         if !preview {
             self.cancel_focus_cycle();
-            let order = self.focus_history.candidates(self.focused_window, available.clone());
+            let order = self.focus_history.candidates(self.focused_window, &available);
             let mut cycle = ferese_core::FocusCycle::new(order, self.focused_window);
             if let Some(id) = cycle.advance(reverse, &available) {
                 self.activate_managed_window(id);
@@ -57,7 +57,7 @@ impl Ferese {
             return;
         }
         if self.focus_cycle.is_none() {
-            let order = self.focus_history.candidates(self.focused_window, available.clone());
+            let order = self.focus_history.candidates(self.focused_window, &available);
             if order.len() < 2 {
                 return;
             }

compositor/src/state/hit_testing.rs

@@ -166,10 +166,7 @@ impl Ferese {
         };
 
         if overview_active {
-            let mut candidates = self.windows.ids().keys().cloned().collect::<Vec<_>>();
-            // Match Overview's front-to-back render order during overlapping motion.
-            candidates.sort_by_key(|window| std::cmp::Reverse(self.windows.ids().get(window).map_or(0, |id| id.0)));
-            candidates.iter().find_map(hit)
+            self.windows.overview_windows().find_map(hit)
         } else {
             self.space.elements().rev().find_map(hit)
         }

compositor/src/state/layout.rs

@@ -59,6 +59,7 @@ impl Ferese {
         // Consume idle time before setting new targets; it must not become a
         // large first animation step after a keypress on an idle desktop.
         self.advance_animations(Instant::now());
+        self.stacking_cache.invalidate();
         self.arrange_layers();
         let mut previous_scrolling_world_x = self.windows.take_world_positions();
         let pending_column_width_cycles = self.windows.take_column_width_requests();
@@ -303,7 +304,7 @@ impl Ferese {
 
             let location = (visual.x.round() as i32, visual.y.round() as i32);
 
-            self.space.map_element(window.clone(), location, false);
+            self.map_window_geometry(window.clone(), location.into());
             if let Some(toplevel) = window.toplevel() {
                 let state_changed = toplevel.with_pending_state(|state| {
                     if natural_pending {
@@ -372,39 +373,66 @@ impl Ferese {
         }
 
         self.space.raise_element(window, activate);
+        self.stacking_cache.remapped();
         self.sync_window_stacking();
     }
 
+    pub(crate) fn invalidate_window_stacking(&mut self) {
+        self.stacking_cache.invalidate();
+    }
+
     pub(crate) fn sync_window_stacking(&mut self) {
-        let mut windows = self.space.elements().cloned().collect::<Vec<_>>();
-        windows.sort_by_key(|window| {
-            let id = self.windows.ids().get(window).copied();
-            let geometry = id.and_then(|id| self.windows.geometry(&id));
-            let floating =
-                id.is_some_and(|id| matches!(self.workspaces.placement(id), Some(WindowPlacement::Floating { .. })));
-            let priority = crate::stacking::layer_priority(
-                floating,
-                geometry.is_some_and(|geometry| geometry.is_zooming()),
-                geometry.is_some_and(|geometry| geometry.is_fullscreen()),
-                floating
-                    && id.is_some_and(|id| {
-                        self.floating_above_fullscreen.get(&id).is_some_and(|parent| {
-                            self.workspaces
-                                .workspace_for_window(id)
-                                .and_then(|workspace| self.workspaces.workspace(workspace))
-                                .is_some_and(|workspace| workspace.fullscreen == Some(*parent))
-                        })
-                    }),
-            );
-            (priority, id.map_or(usize::MAX, |id| self.window_stack.rank(id)))
-        });
-        if stacking_order_settled(self.space.elements(), &windows, |window| window.z_index()) {
+        let revision = self.window_stack.revision();
+        let rebuild = self.stacking_cache.needs_rebuild(revision, self.space.elements().len());
+
+        if !rebuild && !self.stacking_cache.needs_restore() {
             return;
         }
 
-        for window in windows {
-            self.space.raise_element(&window, false);
+        if rebuild {
+            let mut windows = self.space.elements().cloned().collect::<Vec<_>>();
+            windows.sort_by_key(|window| {
+                let id = self.windows.ids().get(window).copied();
+                let geometry = id.and_then(|id| self.windows.geometry(&id));
+                let floating = id
+                    .is_some_and(|id| matches!(self.workspaces.placement(id), Some(WindowPlacement::Floating { .. })));
+                let priority = crate::stacking::layer_priority(
+                    floating,
+                    geometry.is_some_and(|geometry| geometry.is_zooming()),
+                    geometry.is_some_and(|geometry| geometry.is_fullscreen()),
+                    floating
+                        && id.is_some_and(|id| {
+                            self.floating_above_fullscreen.get(&id).is_some_and(|parent| {
+                                self.workspaces
+                                    .workspace_for_window(id)
+                                    .and_then(|workspace| self.workspaces.workspace(workspace))
+                                    .is_some_and(|workspace| workspace.fullscreen == Some(*parent))
+                            })
+                        }),
+                );
+                (priority, id.map_or(usize::MAX, |id| self.window_stack.rank(id)))
+            });
+            self.stacking_cache.replace(windows, revision);
         }
+
+        if !stacking_order_settled(self.space.elements(), self.stacking_cache.order(), |window| {
+            window.z_index()
+        }) {
+            for window in self.stacking_cache.order() {
+                self.space.raise_element(window, false);
+            }
+        }
+
+        self.stacking_cache.restored();
+    }
+
+    pub(crate) fn map_window_geometry(&mut self, window: Window, location: Point<i32, Logical>) {
+        if self.space.element_location(&window) == Some(location) {
+            return;
+        }
+
+        self.space.map_element(window, location, false);
+        self.stacking_cache.remapped();
     }
 
     pub(super) fn tiled_layout(&mut self, bounds: Rect) -> Result<LayoutResult, ferese_layout::LayoutError> {

compositor/src/state/navigation.rs

@@ -139,12 +139,7 @@ impl Ferese {
         {
             tracing::warn!(%error, ?current, ?next, "failed to slide swipe focus");
         }
-        let Some(window) = self
-            .windows
-            .ids()
-            .iter()
-            .find_map(|(window, id)| (*id == next).then(|| window.clone()))
-        else {
+        let Some(window) = self.windows.window(next).cloned() else {
             return;
         };
         let Some(surface) = window.toplevel().map(|toplevel| toplevel.wl_surface().clone()) else {
@@ -306,12 +301,7 @@ impl Ferese {
     }
 
     pub(crate) fn activate_managed_window(&mut self, id: WindowId) -> bool {
-        let Some(window) = self
-            .windows
-            .ids()
-            .iter()
-            .find_map(|(window, window_id)| (*window_id == id).then(|| window.clone()))
-        else {
+        let Some(window) = self.windows.window(id).cloned() else {
             return false;
         };
         if !activate_window_workspace(&mut self.workspaces, &mut self.output_workspaces, id) {
@@ -441,6 +431,7 @@ impl Ferese {
                 .get_mut(&output)
                 .expect("gesture output exists")
                 .held_progress = Some(progress);
+            self.refresh_workspace_slide_offsets();
             self.backdrop_generation = self.backdrop_generation.wrapping_add(1);
             self.cursor_redraw_pending = true;
             return;
@@ -555,14 +546,11 @@ impl Ferese {
             self.focus_lock_surface();
             return;
         }
-        let surface = self.focused_window.and_then(|focused| {
-            self.windows.ids().iter().find_map(|(window, id)| {
-                (*id == focused)
-                    .then(|| window.toplevel())
-                    .flatten()
-                    .map(|toplevel| toplevel.wl_surface().clone())
-            })
-        });
+        let surface = self
+            .focused_window
+            .and_then(|focused| self.windows.window(focused))
+            .and_then(|window| window.toplevel())
+            .map(|toplevel| toplevel.wl_surface().clone());
 
         self.seat.get_keyboard().expect("seat has a keyboard").set_focus(
             self,

compositor/src/state/outputs.rs

@@ -29,6 +29,8 @@ impl Ferese {
         match registration {
             Ok(_) => {
                 self.output_ids.insert(output.clone(), output_id);
+                self.outputs_by_id.insert(output_id, output.clone());
+                self.output_names.insert(output_id, output.name());
                 self.restore_output_focus();
                 let visible = self.visible_workspace_ids();
                 self.reconcile_workspaces(&visible);
@@ -45,6 +47,8 @@ impl Ferese {
             return;
         };
 
+        self.outputs_by_id.remove(&output_id);
+        self.output_names.remove(&output_id);
         self.workspace_slides.remove(&output_id);
         self.render.remove_output(output_id);
         self.pending_screencopies.retain(|capture| {
@@ -113,9 +117,7 @@ impl Ferese {
 
     pub(crate) fn focused_output(&self) -> Option<&Output> {
         let focused = self.output_workspaces.focused_output()?;
-        self.output_ids
-            .iter()
-            .find_map(|(output, id)| (*id == focused).then_some(output))
+        self.outputs_by_id.get(&focused)
     }
 
     pub(crate) fn restore_output_focus(&mut self) {

compositor/src/state/prediction.rs

@@ -5,6 +5,8 @@ use super::*;
 pub(crate) struct FrameScene {
     pub windows: HashMap<WindowId, WindowFrame>,
     pub overview: crate::overview::OverviewMotion,
+    // Plane selection and scheduling reuse the activity sampled with this scene.
+    pub animating: bool,
 }
 
 pub(crate) struct WindowFrame {
@@ -17,6 +19,31 @@ pub(crate) struct WindowFrame {
 }
 
 impl Ferese {
+    fn output_window_records<'a>(
+        &'a self,
+        output: &'a Output,
+        block_resizes: bool,
+    ) -> impl Iterator<Item = (WindowId, &'a super::window_registry::WindowRecord, bool)> + 'a {
+        self.output_id(output)
+            .into_iter()
+            .flat_map(move |output| self.output_workspaces.assigned_workspaces(output))
+            .filter_map(move |id| self.workspaces.workspace(id))
+            .flat_map(move |workspace| {
+                let blocked = block_resizes
+                    && workspace
+                        .layout
+                        .window_ids()
+                        .chain(workspace.floating.iter().copied())
+                        .any(|id| self.windows.record(id).is_some_and(|record| record.resize.is_some()));
+
+                workspace
+                    .layout
+                    .window_ids()
+                    .chain(workspace.floating.iter().copied())
+                    .filter_map(move |id| Some((id, self.windows.record(id)?, blocked)))
+            })
+    }
+
     pub(crate) fn output_has_animations(&self, output: &Output) -> bool {
         if self.overview.is_animating(self.spring_config) || !self.dismissing_popups.is_empty() {
             return true;
@@ -30,17 +57,17 @@ impl Ferese {
             return true;
         }
 
-        self.windows.records().any(|(id, record)| {
+        self.output_window_records(output, false).any(|(id, record, _)| {
             let Some(mut geometry) = record.geometry else {
                 return false;
             };
 
-            if !self.window_belongs_to_output(*id, output) {
+            if !self.window_belongs_to_output(id, output) {
                 return false;
             }
 
             if record.resize.is_some()
-                || self.render.snapshot(id).is_some()
+                || self.render.snapshot(&id).is_some()
                 || record.closing.as_ref().is_some_and(|close| !close.close_sent)
                 || record.focus.as_ref().is_some_and(|focus| focus.is_animating())
                 || record.dimming.as_ref().is_some_and(|dim| dim.is_animating())
@@ -52,7 +79,7 @@ impl Ferese {
                 return true;
             }
 
-            let Some(workspace) = self.workspaces.workspace_for_window(*id) else {
+            let Some(workspace) = self.workspaces.workspace_for_window(id) else {
                 return false;
             };
 
@@ -71,28 +98,28 @@ impl Ferese {
     }
 
     pub(crate) fn sample_frame(&self, output: &Output, horizon: Duration) -> FrameScene {
-        let delta = if self.animations_enabled && self.output_has_animations(output) {
+        let animating = self.output_has_animations(output);
+        let delta = if self.animations_enabled && animating {
             horizon.min(Duration::from_millis(100)).mul_f64(self.animation_speed)
         } else {
             Duration::ZERO
         };
 
         let overview = self.overview.sample(delta, self.spring_config);
-        let blocked = self
-            .windows
-            .resizing()
-            .filter_map(|id| self.workspaces.workspace_for_window(*id))
-            .collect::<HashSet<_>>();
+        let predicted_slide_offsets =
+            (!delta.is_zero()).then(|| self.sample_workspace_slide_offsets(self.output_id(output), delta));
+        let slide_offsets = predicted_slide_offsets
+            .as_ref()
+            .unwrap_or(&self.workspace_slide_offsets);
         let mut windows = HashMap::new();
 
-        for (&id, record) in self.windows.records() {
+        for (id, record, blocked) in self.output_window_records(output, !delta.is_zero()) {
             let Some(original) = record.geometry else { continue };
 
             if !self.window_belongs_to_output(id, output) {
                 continue;
             }
 
-            let workspace = self.workspaces.workspace_for_window(id);
             let world = record.world_x.as_ref().and_then(|(workspace, world)| {
                 let viewport = self.viewport_animations.get(workspace)?;
                 let held = self
@@ -103,7 +130,7 @@ impl Ferese {
                 Some((*world, *viewport, held))
             });
             let width = record.coupled_width.as_ref().map(|(_, width)| *width);
-            let geometry = if delta.is_zero() || workspace.is_some_and(|workspace| blocked.contains(&workspace)) {
+            let geometry = if delta.is_zero() || blocked {
                 original
             } else {
                 predict_geometry(
@@ -118,7 +145,11 @@ impl Ferese {
 
             let mut rect = overview.presented_rect(id, geometry.visual.current);
             if !overview.is_presenting() {
-                let (x, y) = self.workspace_slide_offset_at(id, delta);
+                let (x, y) = self
+                    .workspaces
+                    .workspace_for_window(id)
+                    .and_then(|workspace| slide_offsets.get(&workspace).copied())
+                    .unwrap_or_default();
                 rect.x += x;
                 rect.y += y;
             }
@@ -160,7 +191,11 @@ impl Ferese {
             );
         }
 
-        FrameScene { windows, overview }
+        FrameScene {
+            windows,
+            overview,
+            animating,
+        }
     }
 }
 
@@ -259,12 +294,109 @@ mod tests {
             {
                 let forecast = state.sample_frame(&output, horizon);
                 assert!(forecast.windows[&id].geometry.visual.current.x > geometry.visual.current.x);
+                assert!(forecast.animating);
             }
 
             assert_eq!(*state.windows.geometry(&id).unwrap(), geometry);
             assert_eq!(state.last_animation_tick, tick);
         }
 
+        // Sampling one output must not visit or include another output's records.
+        let other = Output::new(
+            "other-forecast".into(),
+            smithay::output::PhysicalProperties {
+                size: (0, 0).into(),
+                subpixel: smithay::output::Subpixel::Unknown,
+                make: "test".into(),
+                model: "test".into(),
+            },
+        );
+        other.change_current_state(
+            Some(smithay::output::Mode {
+                size: (1280, 720).into(),
+                refresh: 240_000,
+            }),
+            Some(smithay::utils::Transform::Normal),
+            None,
+            Some((1920, 0).into()),
+        );
+        state.space.map_output(&other, (1920, 0));
+        state.register_output(&other, "other-forecast".into());
+        let other_workspace = state
+            .output_workspaces
+            .active_workspace(state.output_id(&other).unwrap())
+            .unwrap();
+        let other_id = WindowId(2);
+        state
+            .workspaces
+            .insert_floating_window(other_id, other_workspace, geometry.visual.current, false)
+            .unwrap();
+        state.windows.records.insert(
+            other_id,
+            super::super::window_registry::WindowRecord {
+                geometry: Some(geometry),
+                ..Default::default()
+            },
+        );
+
+        assert_eq!(
+            state
+                .output_window_records(&output, false)
+                .map(|(id, _, _)| id)
+                .collect::<Vec<_>>(),
+            vec![id]
+        );
+        assert_eq!(
+            state
+                .output_window_records(&other, false)
+                .map(|(id, _, _)| id)
+                .collect::<Vec<_>>(),
+            vec![other_id]
+        );
+        assert!(
+            !state
+                .sample_frame(&output, Duration::from_millis(8))
+                .windows
+                .contains_key(&other_id)
+        );
+        assert!(
+            !state
+                .sample_frame(&other, Duration::from_millis(4))
+                .windows
+                .contains_key(&id)
+        );
+
+        let output_id = state.output_id(&output).unwrap();
+        let from = state.workspaces.workspace_for_window(id).unwrap();
+        let to = state.workspaces.create_workspace();
+        state.output_workspaces.assign_workspace(output_id, to).unwrap();
+        let mut slide = WorkspaceSlide::new(None, from, to, SwipeDirection::Left);
+        slide.held_progress = Some(0.25);
+        state.workspace_slides.insert(output_id, slide);
+        state.refresh_workspace_slide_offsets();
+        let offsets = state.workspace_slide_offsets.clone();
+        assert_eq!(offsets[&from].0, -480.0);
+        assert_eq!(offsets[&to].0, 1440.0);
+        assert_eq!(
+            state.sample_frame(&output, Duration::from_millis(8)).windows[&id]
+                .rect
+                .x,
+            state.sample_frame(&output, Duration::from_millis(8)).windows[&id]
+                .geometry
+                .visual
+                .current
+                .x
+                - 480.0
+        );
+        assert_eq!(state.workspace_slide_offsets, offsets);
+        assert!(
+            state
+                .sample_workspace_slide_offsets(state.output_id(&other), Duration::from_millis(8))
+                .is_empty()
+        );
+        state.cancel_workspace_slides();
+        assert!(state.workspace_slide_offsets.is_empty());
+
         // A prediction must neither advance nor expire a client resize barrier.
         state.windows.set_transaction(
             id,
@@ -278,6 +410,12 @@ mod tests {
         state.animations_enabled = false;
         let forecast = state.sample_frame(&output, Duration::from_millis(16));
         assert_eq!(forecast.windows[&id].geometry, geometry);
+
+        let settled = WindowGeometry::new(Rect::new(0., 0., 400., 300.), None);
+        state.windows.set_geometry(id, settled);
+        state.animations_enabled = true;
+        assert!(!state.sample_frame(&output, Duration::ZERO).animating);
+        assert!(state.sample_frame(&other, Duration::ZERO).animating);
     }
 
     #[test]

compositor/src/state/window_registry.rs

@@ -4,6 +4,10 @@ use std::hash::Hash;
 use ferese_animation::{AnimatedValue, WindowGeometry};
 use ferese_core::WorkspaceId;
 use ferese_layout::{ColumnWidth, Rect, WindowId};
+use smithay::desktop::Window;
+use smithay::reexports::wayland_server::protocol::wl_surface::WlSurface;
+use smithay::wayland::compositor::with_states;
+use smithay::wayland::shell::xdg::XdgToplevelSurfaceData;
 
 use crate::resize_transaction::ResizeTransaction;
 
@@ -12,6 +16,10 @@ use crate::resize_transaction::ResizeTransaction;
 #[derive(Default)]
 pub(crate) struct WindowRecord {
     pub geometry: Option<WindowGeometry>,
+    pub surface: Option<WlSurface>,
+    pub app_id: String,
+    pub title: String,
+    pub metadata_revision: u64,
     pub resize: Option<ResizeTransaction>,
     pub focus: Option<crate::dimming::DimAnimation>,
     pub dimming: Option<crate::dimming::DimAnimation>,
@@ -32,7 +40,11 @@ pub(crate) struct WindowRecord {
 /// handle always updates its record as well. IDs are never reused on remapping.
 pub(crate) struct WindowRegistry<W> {
     ids: HashMap<W, WindowId>,
+    by_id: HashMap<WindowId, W>,
+    surface_ids: HashMap<WlSurface, WindowId>,
     pub(super) records: HashMap<WindowId, WindowRecord>,
+    // Ascending IDs; overview reverses this for front-to-back traversal.
+    overview_order: Vec<WindowId>,
     next_id: u64,
 }
 
@@ -40,7 +52,10 @@ impl<W> Default for WindowRegistry<W> {
     fn default() -> Self {
         Self {
             ids: HashMap::new(),
+            by_id: HashMap::new(),
+            surface_ids: HashMap::new(),
             records: HashMap::new(),
+            overview_order: Vec::new(),
             next_id: 1,
         }
     }
@@ -54,10 +69,16 @@ impl<W: Eq + Hash> WindowRegistry<W> {
         id
     }
 
-    pub fn register(&mut self, window: W, id: WindowId) {
+    pub fn register(&mut self, window: W, id: WindowId)
+    where
+        W: Clone,
+    {
         assert!(!self.ids.contains_key(&window), "window already registered");
         assert!(!self.records.contains_key(&id), "window ID already registered");
 
+        let index = self.overview_order.partition_point(|existing| existing.0 < id.0);
+        self.overview_order.insert(index, id);
+        self.by_id.insert(id, window.clone());
         self.ids.insert(window, id);
         self.records.insert(id, WindowRecord::default());
     }
@@ -66,6 +87,24 @@ impl<W: Eq + Hash> WindowRegistry<W> {
         &self.ids
     }
 
+    /// Overview render and hit order, with the newest ID in front. Normal
+    /// stacking changes do not affect this independent presentation order.
+    pub fn overview_windows(&self) -> impl DoubleEndedIterator<Item = &W> {
+        self.overview_order.iter().rev().filter_map(|id| self.by_id.get(id))
+    }
+
+    pub fn window(&self, id: WindowId) -> Option<&W> {
+        self.by_id.get(&id)
+    }
+
+    pub fn id_for_surface(&self, surface: &WlSurface) -> Option<WindowId> {
+        self.surface_ids.get(surface).copied()
+    }
+
+    pub fn ordered_ids(&self) -> impl DoubleEndedIterator<Item = WindowId> + '_ {
+        self.overview_order.iter().copied()
+    }
+
     pub fn record(&self, id: WindowId) -> Option<&WindowRecord> {
         self.records.get(&id)
     }
@@ -74,14 +113,14 @@ impl<W: Eq + Hash> WindowRegistry<W> {
         self.records.get_mut(&id)
     }
 
-    pub fn records_mut(&mut self) -> impl Iterator<Item = (&WindowId, &mut WindowRecord)> {
-        self.records.iter_mut()
-    }
-
     pub fn records(&self) -> impl Iterator<Item = (&WindowId, &WindowRecord)> {
         self.records.iter()
     }
 
+    pub fn records_mut(&mut self) -> impl Iterator<Item = (&WindowId, &mut WindowRecord)> {
+        self.records.iter_mut()
+    }
+
     pub fn take_world_positions(&mut self) -> HashMap<WindowId, (WorkspaceId, AnimatedValue)> {
         self.records
             .iter_mut()
@@ -140,7 +179,17 @@ impl<W: Eq + Hash> WindowRegistry<W> {
 
     pub fn remove(&mut self, window: &W) -> Option<WindowId> {
         let id = self.ids.remove(window)?;
-        self.records.remove(&id);
+        self.by_id.remove(&id);
+        if let Some(record) = self.records.remove(&id)
+            && let Some(surface) = record.surface
+        {
+            self.surface_ids.remove(&surface);
+        }
+        let index = self
+            .overview_order
+            .binary_search_by_key(&id.0, |id| id.0)
+            .expect("registered windows have an overview entry");
+        self.overview_order.remove(index);
 
         Some(id)
     }
@@ -153,10 +202,96 @@ impl<W: Eq + Hash> WindowRegistry<W> {
     }
 }
 
+impl WindowRegistry<Window> {
+    pub fn register_window(&mut self, window: Window, id: WindowId) {
+        let surface = window.toplevel().map(|toplevel| toplevel.wl_surface().clone());
+        self.register(window, id);
+
+        if let Some(surface) = surface {
+            self.surface_ids.insert(surface.clone(), id);
+            self.records.get_mut(&id).unwrap().surface = Some(surface.clone());
+            self.refresh_metadata(&surface);
+        }
+    }
+
+    pub fn refresh_metadata(&mut self, surface: &WlSurface) -> bool {
+        let Some(id) = self.id_for_surface(surface) else {
+            return false;
+        };
+        let record = self.records.get_mut(&id).unwrap();
+        with_states(surface, |states| {
+            let attributes = states.data_map.get::<XdgToplevelSurfaceData>().unwrap().lock().unwrap();
+            let app_id = attributes.app_id.as_deref().unwrap_or_default();
+            let title = attributes.title.as_deref().unwrap_or_default();
+            let changed = record.app_id != app_id || record.title != title;
+
+            if changed {
+                record.app_id.clear();
+                record.app_id.push_str(app_id);
+                record.title.clear();
+                record.title.push_str(title);
+                record.metadata_revision = record.metadata_revision.wrapping_add(1);
+            }
+
+            changed
+        })
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
 
+    #[test]
+    fn overview_order_tracks_registration_removal_and_remapping() {
+        let mut windows = WindowRegistry::default();
+        let first = windows.allocate_id();
+        let second = windows.allocate_id();
+        let third = windows.allocate_id();
+        // Registration need not happen in allocation order.
+        windows.register("second", second);
+        windows.register("first", first);
+        windows.register("third", third);
+        assert_eq!(
+            windows.overview_windows().copied().collect::<Vec<_>>(),
+            ["third", "second", "first"]
+        );
+
+        windows.remove(&"second");
+        assert_eq!(
+            windows.overview_windows().copied().collect::<Vec<_>>(),
+            ["third", "first"]
+        );
+        windows.remove(&"first");
+        let remapped = windows.allocate_id();
+        windows.register("first", remapped);
+        assert_eq!(
+            windows.overview_windows().copied().collect::<Vec<_>>(),
+            ["first", "third"]
+        );
+
+        windows.remove(&"first");
+        windows.remove(&"third");
+        assert_eq!(windows.overview_windows().count(), 0);
+    }
+
+    #[test]
+    fn overview_iteration_borrows_handles_and_removal_releases_cached_handles() {
+        let handle = std::rc::Rc::new("surface");
+        let mut windows = WindowRegistry::default();
+        let id = windows.allocate_id();
+        windows.register(handle.clone(), id);
+        assert_eq!(std::rc::Rc::strong_count(&handle), 3);
+
+        for _ in 0..100 {
+            assert!(std::rc::Rc::ptr_eq(windows.overview_windows().next().unwrap(), &handle));
+            assert_eq!(std::rc::Rc::strong_count(&handle), 3);
+        }
+
+        windows.remove(&handle);
+        assert_eq!(std::rc::Rc::strong_count(&handle), 1);
+    }
+
     #[test]
     fn unmap_drops_metadata_and_late_updates_cannot_resurrect_it() {
         let mut windows = WindowRegistry::default();

compositor/src/state/windows.rs

@@ -115,7 +115,7 @@ impl Ferese {
             return;
         }
 
-        self.windows.register(window.clone(), id);
+        self.windows.register_window(window.clone(), id);
         self.windows.update(id, |w| w.placement_anchor = Some(anchor));
 
         if rule.width.is_none() && rule.height.is_none() && client_size(&window).is_none() && remembered_work.is_none()
@@ -156,7 +156,7 @@ impl Ferese {
             return;
         }
 
-        self.windows.register(window.clone(), id);
+        self.windows.register_window(window.clone(), id);
         self.window_stack.insert(id);
         if focus_new_window {
             self.focused_window = Some(id);
@@ -196,7 +196,7 @@ impl Ferese {
             return;
         }
 
-        self.windows.register(window.clone(), id);
+        self.windows.register_window(window.clone(), id);
         self.window_stack.insert(id);
         if client_size(&window).is_none() {
             self.windows.update(id, |w| w.natural_floating_pending = true);
@@ -649,7 +649,7 @@ impl Ferese {
     }
 
     pub(crate) fn close_managed_window(&mut self, id: WindowId) -> bool {
-        if !self.windows.ids().values().any(|window_id| *window_id == id) {
+        if !self.windows.window(id).is_some() {
             return false;
         }
 
@@ -666,12 +666,7 @@ impl Ferese {
     }
 
     pub(super) fn send_window_close(&self, id: WindowId) {
-        let Some(toplevel) = self
-            .windows
-            .ids()
-            .iter()
-            .find_map(|(window, window_id)| (*window_id == id).then(|| window.toplevel()).flatten())
-        else {
+        let Some(toplevel) = self.windows.window(id).and_then(|window| window.toplevel()) else {
             return;
         };