diff --git a/compositor/src/activities.rs b/compositor/src/activities.rs
index 90fa60a..e80a8f7 100644
--- a/compositor/src/activities.rs
+++ b/compositor/src/activities.rs
@@ -51,7 +51,7 @@ impl Default for Engine {
             ),
             rules: Arc::new(RwLock::new(Arc::new(Rules {
                 enabled: false,
-                matcher: ferese_config::activities::Matcher::new(&settings)
+                matcher: ferese_config::activities::Matcher::try_new(&settings)
                     .expect("built-in rules"),
             }))),
             monitor: None,
@@ -691,7 +691,7 @@ mod tests {
             .spawn()
             .unwrap();
         let (owner, fd, _) = crate::ipc::activity_owner::inspect(child.id()).unwrap();
-        let matched = ferese_config::activities::Matcher::new(&Default::default())
+        let matched = ferese_config::activities::Matcher::try_new(&Default::default())
             .unwrap()
             .matches("cargo test", "/tmp", &[])
             .unwrap();
@@ -707,7 +707,7 @@ mod tests {
         let mut engine = Engine::default();
         let (owner, fd, _) = crate::ipc::activity_owner::inspect(std::process::id()).unwrap();
         let settings = ferese_config::activities::Settings::default();
-        let matched = ferese_config::activities::Matcher::new(&settings)
+        let matched = ferese_config::activities::Matcher::try_new(&settings)
             .unwrap()
             .matches("cargo test", "/tmp/test", &[])
             .unwrap();
@@ -859,7 +859,7 @@ mod tests {
     #[test]
     fn rule_is_pinned_across_atomic_reload_and_no_raw_metadata_is_published() {
         let settings = ferese_config::activities::Settings::default();
-        let matched = ferese_config::activities::Matcher::new(&settings)
+        let matched = ferese_config::activities::Matcher::try_new(&settings)
             .unwrap()
             .matches("cargo test --secret", "/secret/cwd", &[])
             .unwrap();
@@ -883,7 +883,7 @@ mod tests {
         replacement.rules[0].title = "Replacement".into();
         engine.configure(
             &replacement,
-            ferese_config::activities::Matcher::new(&replacement).unwrap(),
+            ferese_config::activities::Matcher::try_new(&replacement).unwrap(),
         );
         let after = engine.store.entries().next().unwrap();
         assert_eq!(after.data.title, "cargo test");
diff --git a/compositor/src/backends/direct.rs b/compositor/src/backends/direct.rs
index 96b4eda..6de252b 100644
--- a/compositor/src/backends/direct.rs
+++ b/compositor/src/backends/direct.rs
@@ -442,12 +442,11 @@ pub fn init(event_loop: &mut EventLoop<Ferese>, state: &mut Ferese) -> Result<()
                     if let Some(token) = backend.power_retry.take() {
                         handle.remove(token);
                     }
-                    backend
-                        .presentation
-                        .values_mut()
-                        .for_each(PresentationClock::reset_timing);
-                    backend.devices.values_mut().for_each(|device| {
-                        device.outputs.values_mut().for_each(|output| {
+                    for clock in backend.presentation.values_mut() {
+                        clock.reset_timing();
+                    }
+                    for device in backend.devices.values_mut() {
+                        for output in device.outputs.values_mut() {
                             output.gamma.suspend();
                             cancel_output_timers(&handle, output);
                             output.surface.reset_buffers();
@@ -456,9 +455,9 @@ pub fn init(event_loop: &mut EventLoop<Ferese>, state: &mut Ferese) -> Result<()
                             output.capture_texture = None;
                             output.frame_pending = false;
                             output.power.suspended();
-                        });
+                        }
                         device.drm.pause();
-                    });
+                    }
                 }
 
                 state.display_presentation.clear();
@@ -2178,30 +2177,27 @@ fn send_frame_callbacks(state: &mut Ferese, output: &Output) {
         state.lock_frame_callbacks(output);
         return;
     }
-    state
-        .space
-        .elements()
-        .filter(|window| {
-            state
-                .windows
-                .ids()
-                .get(*window)
-                .is_some_and(|id| state.window_belongs_to_output(*id, output))
-        })
-        .for_each(|window| {
-            window.send_frame(output, state.start_time.elapsed(), None, |surface, _| {
-                eligible.get(&surface.into()).cloned()
-            });
+    let visible_windows = state.space.elements().filter(|window| {
+        state
+            .windows
+            .ids()
+            .get(*window)
+            .is_some_and(|id| state.window_belongs_to_output(*id, output))
+    });
+    for window in visible_windows {
+        window.send_frame(output, state.start_time.elapsed(), None, |surface, _| {
+            eligible.get(&surface.into()).cloned()
         });
+    }
     let layers = layer_map_for_output(output)
         .layers()
         .cloned()
         .collect::<Vec<_>>();
-    layers.iter().for_each(|layer| {
+    for layer in &layers {
         layer.send_frame(output, state.start_time.elapsed(), None, |surface, _| {
             eligible.get(&surface.into()).cloned()
         });
-    });
+    }
     state.send_cursor_frame(output);
     state.space.refresh();
     state.popups.cleanup();
diff --git a/compositor/src/backends/direct/topology.rs b/compositor/src/backends/direct/topology.rs
index e9508a0..f646675 100644
--- a/compositor/src/backends/direct/topology.rs
+++ b/compositor/src/backends/direct/topology.rs
@@ -2,11 +2,11 @@
 use std::path::PathBuf;
 
 use super::{
-    DrmNode, Duration, Ferese, HashMap, HashSet, Instant, OutputMode, Path, PresentationClock,
-    RegistrationToken, Scale, Session, TimeoutAction, Timer, all_gpus, cancel_output_timers,
-    drm_device_key, lid, monotonic_now, open_device, output_transform, refresh_connected_info,
-    refresh_monitor_policy, remember_applied_configuration, remove_device, rescan_device,
-    sync_battery_timer, transaction, validate_desired_outputs,
+    DrmNode, Duration, Ferese, HashMap, HashSet, Instant, OutputMode, Path, RegistrationToken,
+    Scale, Session, TimeoutAction, Timer, all_gpus, cancel_output_timers, drm_device_key, lid,
+    monotonic_now, open_device, output_transform, refresh_connected_info, refresh_monitor_policy,
+    remember_applied_configuration, remove_device, rescan_device, sync_battery_timer, transaction,
+    validate_desired_outputs,
 };
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
@@ -203,10 +203,9 @@ pub(super) fn reconcile_outputs(state: &mut Ferese, reactivate: bool) {
     backend.topology.dirty = false;
     backend.output_error = None;
     if reactivate {
-        backend
-            .presentation
-            .values_mut()
-            .for_each(PresentationClock::reset_timing);
+        for clock in backend.presentation.values_mut() {
+            clock.reset_timing();
+        }
     }
     if let Some(token) = backend.topology.retry_timer.take() {
         state.loop_handle.remove(token);
diff --git a/compositor/src/config.rs b/compositor/src/config.rs
index e16a6aa..cbcd8b1 100644
--- a/compositor/src/config.rs
+++ b/compositor/src/config.rs
@@ -149,7 +149,7 @@ impl Config {
         let binding_modes = self.binding_modes(&input_settings, &bindings)?;
         Ok(crate::RuntimeConfig {
             activity_settings: self.activities.clone(),
-            activity_matcher: ferese_config::activities::Matcher::new(&self.activities)
+            activity_matcher: ferese_config::activities::Matcher::try_new(&self.activities)
                 .map_err(ConfigError::Binding)?,
             lock_idle: self.lock_screen.validate()?,
             night_light: self.night_light.validate().map_err(ConfigError::Binding)?,
diff --git a/compositor/src/render/corner_tests.rs b/compositor/src/render/corner_tests.rs
index 85b7f54..e832e33 100644
--- a/compositor/src/render/corner_tests.rs
+++ b/compositor/src/render/corner_tests.rs
@@ -344,7 +344,7 @@ fn panel_shader_matches_core_outlines_and_resets_for_popovers() {
                         },
                         bounds,
                         &groups,
-                        PixelGrid::new(scale).unwrap(),
+                        PixelGrid::try_new(scale).unwrap(),
                     )
                     .unwrap(),
                 );
diff --git a/compositor/src/render/materials.rs b/compositor/src/render/materials.rs
index ae90bfc..b897ee4 100644
--- a/compositor/src/render/materials.rs
+++ b/compositor/src/render/materials.rs
@@ -896,7 +896,7 @@ mod region_geometry_tests {
                         },
                         ferese_layout::Rect::new((320. - width) / 2., 0., width, 44.),
                         &[],
-                        PixelGrid::new(scale).unwrap(),
+                        PixelGrid::try_new(scale).unwrap(),
                     )
                     .unwrap();
                     let presentation = crate::effects::PanelPresentation {
@@ -947,7 +947,7 @@ mod region_geometry_tests {
         use ferese_panel::shape::{AnchoredRadii, PixelGrid};
         for scale in [1., 1.25, 1.5, 2.] {
             for edge in [ferese_panel::Edge::Top, ferese_panel::Edge::Bottom] {
-                let mut hub = Hub::new(Profile::default(), 34.).unwrap();
+                let mut hub = Hub::try_new(Profile::default(), 34.).unwrap();
                 for mode in [Mode::Peek, Mode::Idle] {
                     hub.retarget(mode, [400., 300.]).unwrap();
                     for frame in 0..160 {
@@ -977,7 +977,7 @@ mod region_geometry_tests {
                             },
                             bounds,
                             &[],
-                            PixelGrid::new(scale).unwrap(),
+                            PixelGrid::try_new(scale).unwrap(),
                         )
                         .unwrap();
                         // Reproduce the f32 transport and logical capture bounds used by native materials.
diff --git a/crates/ferese-activities/src/pomodoro.rs b/crates/ferese-activities/src/pomodoro.rs
index f04024b..3bfb60e 100644
--- a/crates/ferese-activities/src/pomodoro.rs
+++ b/crates/ferese-activities/src/pomodoro.rs
@@ -54,6 +54,7 @@ pub enum Phase {
     LongBreak,
 }
 impl Phase {
+    #[must_use]
     pub fn label(self) -> &'static str {
         match self {
             Self::Work => "Work",
@@ -97,6 +98,7 @@ impl Session {
             deadline: Some(now.saturating_add(remaining_ms)),
         })
     }
+    #[must_use]
     pub fn remaining(&self, now: Time) -> u64 {
         self.deadline
             .map_or(self.remaining_ms, |deadline| deadline.saturating_sub(now))
diff --git a/crates/ferese-activities/src/store.rs b/crates/ferese-activities/src/store.rs
index 83b357b..0841daa 100644
--- a/crates/ferese-activities/src/store.rs
+++ b/crates/ferese-activities/src/store.rs
@@ -39,6 +39,7 @@ pub enum Value {
 }
 
 impl Value {
+    #[must_use]
     pub fn remaining_ms(&self, now: Time) -> Option<u64> {
         match self {
             Self::Countdown {
@@ -245,6 +246,7 @@ pub struct Activity {
 }
 
 impl Activity {
+    #[must_use]
     pub fn eligible(&self, now: Time, dnd: bool) -> bool {
         now >= self.eligible_at
             && match self.state {
@@ -256,6 +258,7 @@ impl Activity {
             }
     }
 
+    #[must_use]
     pub fn score(&self, now: Time, ceiling: u8) -> u16 {
         u16::from(self.data.priority.min(ceiling))
             + if now < self.eligible_at.saturating_add(BOOST_MS) {
@@ -280,6 +283,7 @@ pub struct Store {
 }
 
 impl Store {
+    #[must_use]
     pub fn new(session: u64) -> Self {
         Self {
             limits: Limits::default(),
@@ -289,6 +293,7 @@ impl Store {
         }
     }
 
+    #[must_use]
     pub fn session(&self) -> u64 {
         self.session
     }
@@ -297,6 +302,7 @@ impl Store {
         self.entries.values()
     }
 
+    #[must_use]
     pub fn resolve(&self, owner: Owner, local: &str) -> Option<&Id> {
         self.entries
             .keys()
@@ -477,6 +483,7 @@ impl Store {
         before != self.entries.len()
     }
 
+    #[must_use]
     pub fn next_deadline(&self, now: Time) -> Option<Time> {
         self.entries
             .values()
diff --git a/crates/ferese-animation/src/gesture.rs b/crates/ferese-animation/src/gesture.rs
index e69e8fe..8c57199 100644
--- a/crates/ferese-animation/src/gesture.rs
+++ b/crates/ferese-animation/src/gesture.rs
@@ -30,6 +30,7 @@ impl VelocityTracker {
         }
     }
 
+    #[must_use]
     pub fn velocity(&self, now: Duration) -> f64 {
         let Some(&(last, origin)) = self.samples.back() else {
             return 0.0;
@@ -87,6 +88,7 @@ impl VelocityTracker {
     }
 }
 
+#[must_use]
 pub fn project(position: f64, velocity: f64, rate: f64) -> f64 {
     if !velocity.is_finite() || !(0.0..1.0).contains(&rate) || rate == 0.0 {
         return position;
@@ -96,6 +98,7 @@ pub fn project(position: f64, velocity: f64, rate: f64) -> f64 {
 
 /// Nonlinear resistance, bounded by `extent`; the derivative transfers the
 /// velocity of the displayed (resisted) position into the release spring.
+#[must_use]
 pub fn rubber_band(distance: f64, extent: f64, resistance: f64) -> (f64, f64) {
     if !distance.is_finite()
         || !extent.is_finite()
diff --git a/crates/ferese-animation/src/settings.rs b/crates/ferese-animation/src/settings.rs
index 1a21e84..d5b5b92 100644
--- a/crates/ferese-animation/src/settings.rs
+++ b/crates/ferese-animation/src/settings.rs
@@ -24,6 +24,7 @@ impl Default for MotionSettings {
 }
 
 impl MotionSettings {
+    #[must_use]
     pub fn motion_enabled(self) -> bool {
         self.enabled && !self.reduced_motion
     }
@@ -53,6 +54,7 @@ impl MotionSettings {
     }
 
     /// Only small opacity changes should use a timed duration.
+    #[must_use]
     pub fn duration(self, milliseconds: f64) -> std::time::Duration {
         if !self.motion_enabled() {
             return std::time::Duration::ZERO;
diff --git a/crates/ferese-animation/src/window_geometry.rs b/crates/ferese-animation/src/window_geometry.rs
index ac45b47..100d269 100644
--- a/crates/ferese-animation/src/window_geometry.rs
+++ b/crates/ferese-animation/src/window_geometry.rs
@@ -74,14 +74,17 @@ pub struct AnimatedValue {
 }
 
 impl AnimatedValue {
+    #[must_use]
     pub fn needs_update(&self, target: f64) -> bool {
         self.target != target || self.is_animating()
     }
 
+    #[must_use]
     pub fn is_animating(&self) -> bool {
         self.current != self.target || self.velocity != 0.0
     }
 
+    #[must_use]
     pub fn new(value: f64) -> Self {
         let value = finite_or_zero(value);
 
@@ -148,6 +151,7 @@ impl AnimatedValue {
 }
 
 impl AnimatedRect {
+    #[must_use]
     pub fn new(rect: Rect) -> Self {
         Self {
             current: rect,
@@ -228,6 +232,7 @@ impl AnimatedRect {
         }
     }
 
+    #[must_use]
     pub fn is_settled(&self, config: SpringConfig) -> bool {
         let config = config.normalized();
         rect_distance(self.current, self.target) <= config.position_tolerance
@@ -242,6 +247,7 @@ pub struct ClientSize {
 }
 
 impl ClientSize {
+    #[must_use]
     pub fn from_rect(rect: Rect) -> Self {
         Self {
             width: (rect.width.round() as i32).max(1),
@@ -279,16 +285,19 @@ impl ClientGeometry {
         matches_target
     }
 
+    #[must_use]
     pub fn waiting_for_commit(&self) -> bool {
         self.waiting_since.is_some()
     }
 
     /// The hard bound for the current uninterrupted client-buffer wait.
+    #[must_use]
     pub fn commit_deadline(&self) -> Option<Duration> {
         self.waiting_since
             .map(|started| started + CLIENT_COMMIT_TIMEOUT)
     }
 
+    #[must_use]
     pub fn timed_out(&self, now: Duration) -> bool {
         self.waiting_since
             .is_some_and(|started| now.saturating_sub(started) >= CLIENT_COMMIT_TIMEOUT)
@@ -329,6 +338,7 @@ struct ZoomTransition {
 }
 
 impl WindowGeometry {
+    #[must_use]
     pub fn new(rect: Rect, committed_size: Option<ClientSize>) -> Self {
         let rect = normalized_rect(rect);
 
@@ -414,10 +424,12 @@ impl WindowGeometry {
         self.client.request_size(size, now).then_some(size)
     }
 
+    #[must_use]
     pub fn is_zooming(&self) -> bool {
         self.zoom.is_some()
     }
 
+    #[must_use]
     pub fn is_fullscreen(&self) -> bool {
         self.mode == PresentationMode::Fullscreen
     }
@@ -486,6 +498,7 @@ impl WindowGeometry {
         geometry_active
     }
 
+    #[must_use]
     pub fn inverse_visual_point(&self, x: f64, y: f64) -> Option<(f64, f64)> {
         let visual = self.visual.current;
         let (scale_x, scale_y) = self.visual_scale()?;
@@ -493,6 +506,7 @@ impl WindowGeometry {
         Some(((x - visual.x) / scale_x, (y - visual.y) / scale_y))
     }
 
+    #[must_use]
     pub fn visual_scale(&self) -> Option<(f64, f64)> {
         let source = self.client.committed_size?;
         let visual = self.visual.current;
diff --git a/crates/ferese-config/src/activities.rs b/crates/ferese-config/src/activities.rs
index 29f846b..0a0cbc0 100644
--- a/crates/ferese-config/src/activities.rs
+++ b/crates/ferese-config/src/activities.rs
@@ -77,7 +77,7 @@ pub struct Matched {
     pub group: Option<String>,
 }
 impl Matcher {
-    pub fn new(settings: &Settings) -> Result<Self, String> {
+    pub fn try_new(settings: &Settings) -> Result<Self, String> {
         let mut rules = Vec::new();
         for rule in &settings.rules {
             let regex = regex::RegexBuilder::new(&rule.pattern)
@@ -167,6 +167,7 @@ fn validate_rule(rule: &Rule, regex: &Regex) -> Result<(), String> {
     Ok(())
 }
 impl Settings {
+    #[must_use]
     pub fn limits(&self) -> ferese_activities::Limits {
         ferese_activities::Limits {
             max_visible: self.max_visible,
@@ -191,7 +192,7 @@ impl Settings {
         if self.rules.iter().any(|rule| !names.insert(&rule.name)) {
             return Err("duplicate activity rule".into());
         }
-        Matcher::new(self).map(|_| ())
+        Matcher::try_new(self).map(|_| ())
     }
 }
 
@@ -397,7 +398,7 @@ mod tests {
         let settings = Settings::default();
         assert!(!settings.sources.shell_hook);
         assert!(!settings.sources.process_watch);
-        let matcher = Matcher::new(&settings).unwrap();
+        let matcher = Matcher::try_new(&settings).unwrap();
         assert!(matcher.matches("secret command", "/tmp", &[]).is_none());
         let matched = matcher.matches("cargo test", "/tmp", &[]).unwrap();
         assert_eq!(matched.title, "cargo test");
diff --git a/crates/ferese-config/src/document.rs b/crates/ferese-config/src/document.rs
index 0e51e9d..551ca1a 100644
--- a/crates/ferese-config/src/document.rs
+++ b/crates/ferese-config/src/document.rs
@@ -33,10 +33,12 @@ pub fn config_path() -> Option<PathBuf> {
         .map(|p| p.join("ferese/config.kdl"))
 }
 
+#[must_use]
 pub fn default_wallpaper() -> &'static str {
     default_wallpaper_for(theme::Appearance::Dark)
 }
 
+#[must_use]
 pub fn default_wallpaper_for(appearance: theme::Appearance) -> &'static str {
     static LIGHT: std::sync::OnceLock<String> = std::sync::OnceLock::new();
     static DARK: std::sync::OnceLock<String> = std::sync::OnceLock::new();
@@ -292,11 +294,13 @@ impl Document {
         Ok(Self { doc, value })
     }
 
+    #[must_use]
     pub fn value(&self) -> &Value {
         &self.value
     }
 
     /// A runtime view; the original KDL remains available for comment-preserving edits.
+    #[must_use]
     pub fn with_theme(&self, theme: &theme::ResolvedTheme) -> Self {
         let mut document = self.clone();
         document.value["theme"] =
@@ -305,6 +309,7 @@ impl Document {
         document
     }
 
+    #[must_use]
     pub fn get(&self, path: &str) -> Option<&Value> {
         let mut value = &self.value;
 
diff --git a/crates/ferese-config/src/families.rs b/crates/ferese-config/src/families.rs
index e6fdb42..21ac54f 100644
--- a/crates/ferese-config/src/families.rs
+++ b/crates/ferese-config/src/families.rs
@@ -30,6 +30,7 @@ pub const BUILTINS: [(&str, &str, &str, &str); 6] = [
     ),
 ];
 
+#[must_use]
 pub fn family_id(preset: &str) -> &str {
     BUILTINS
         .iter()
@@ -37,6 +38,7 @@ pub fn family_id(preset: &str) -> &str {
         .map_or(preset, |row| row.0)
 }
 
+#[must_use]
 pub fn variant(id: &str, appearance: Appearance) -> Option<&'static str> {
     if let Some(row) = BUILTINS.iter().find(|row| row.0 == id) {
         return Some(if appearance == Appearance::Light {
@@ -54,6 +56,7 @@ pub fn variant(id: &str, appearance: Appearance) -> Option<&'static str> {
     }
 }
 
+#[must_use]
 pub fn builtins() -> Vec<Family> {
     BUILTINS
         .iter()
diff --git a/crates/ferese-config/src/file.rs b/crates/ferese-config/src/file.rs
index 4238d54..35fe3aa 100644
--- a/crates/ferese-config/src/file.rs
+++ b/crates/ferese-config/src/file.rs
@@ -58,6 +58,7 @@ impl ConfigFile {
         Ok(file)
     }
 
+    #[must_use]
     pub fn source(&self) -> &str {
         &self.source
     }
diff --git a/crates/ferese-config/src/theme.rs b/crates/ferese-config/src/theme.rs
index 4d7f3b2..66dff31 100644
--- a/crates/ferese-config/src/theme.rs
+++ b/crates/ferese-config/src/theme.rs
@@ -208,6 +208,7 @@ impl Default for Policy {
     }
 }
 
+#[must_use]
 pub fn default_tokens() -> Tokens {
     serde_json::from_value(json!({
             "colors": {"surface_base":"#111821", "surface_raised":"#1E2530", "application_background":"#171E27", "text_primary":"#F4F7FB", "text_muted":"#8793A2",
@@ -224,6 +225,7 @@ pub fn default_tokens() -> Tokens {
         .expect("valid built-in theme")
 }
 
+#[must_use]
 pub fn default_theme() -> ResolvedTheme {
     let mut tokens = default_tokens();
     resolve_gradients(&mut tokens, None);
@@ -527,6 +529,7 @@ pub fn resolve_with_context(
     })
 }
 
+#[must_use]
 pub fn theme_path(directory: &Path, path: &Path) -> PathBuf {
     let path = if let Some(tail) = path.to_str().and_then(|path| path.strip_prefix("~/")) {
         std::env::var_os("HOME")
@@ -690,6 +693,7 @@ pub fn preset(name: &str, appearance: Appearance) -> Result<Tokens, String> {
     Ok(t)
 }
 
+#[must_use]
 pub fn authored_warnings(tokens: &Tokens) -> Vec<String> {
     if let Err(error) = validate(tokens) {
         return vec![error];
diff --git a/crates/ferese-core/src/focus.rs b/crates/ferese-core/src/focus.rs
index a8817e8..34fadc4 100644
--- a/crates/ferese-core/src/focus.rs
+++ b/crates/ferese-core/src/focus.rs
@@ -50,11 +50,13 @@ pub struct FocusCycle {
 }
 
 impl FocusCycle {
+    #[must_use]
     pub fn new(windows: Vec<WindowId>, current: Option<WindowId>) -> Self {
         let selected = current.filter(|id| windows.contains(id));
         Self { windows, selected }
     }
 
+    #[must_use]
     pub fn windows(&self) -> &[WindowId] {
         &self.windows
     }
diff --git a/crates/ferese-core/src/output.rs b/crates/ferese-core/src/output.rs
index 7457277..5506926 100644
--- a/crates/ferese-core/src/output.rs
+++ b/crates/ferese-core/src/output.rs
@@ -16,6 +16,7 @@ pub struct OutputGeometry {
 }
 
 impl OutputGeometry {
+    #[must_use]
     pub const fn new(x: i32, y: i32, width: i32, height: i32) -> Self {
         Self {
             x,
@@ -223,6 +224,7 @@ impl OutputWorkspaceMap {
         })
     }
 
+    #[must_use]
     pub fn assigned_workspaces(
         &self,
         output: OutputId,
@@ -233,22 +235,27 @@ impl OutputWorkspaceMap {
             .flat_map(|state| state.workspaces.iter().copied())
     }
 
+    #[must_use]
     pub fn focused_output(&self) -> Option<OutputId> {
         self.focused
     }
 
+    #[must_use]
     pub fn active_workspace(&self, output: OutputId) -> Option<WorkspaceId> {
         self.outputs.get(&output).map(|state| state.active)
     }
 
+    #[must_use]
     pub fn previous_workspace(&self, output: OutputId) -> Option<WorkspaceId> {
         self.outputs.get(&output).and_then(|state| state.previous)
     }
 
+    #[must_use]
     pub fn output_for_workspace(&self, workspace: WorkspaceId) -> Option<OutputId> {
         self.assignments.get(&workspace).copied()
     }
 
+    #[must_use]
     pub fn home_output(&self, workspace: WorkspaceId) -> Option<OutputId> {
         self.homes.get(&workspace).copied()
     }
@@ -295,6 +302,7 @@ impl OutputWorkspaceMap {
         self.outputs.keys().copied()
     }
 
+    #[must_use]
     pub fn geometry(&self, output: OutputId) -> Option<OutputGeometry> {
         self.outputs.get(&output).map(|state| state.geometry)
     }
diff --git a/crates/ferese-core/src/workspace.rs b/crates/ferese-core/src/workspace.rs
index 2ea15ad..eb1a61f 100644
--- a/crates/ferese-core/src/workspace.rs
+++ b/crates/ferese-core/src/workspace.rs
@@ -39,6 +39,7 @@ impl Default for WorkspaceLayout {
 }
 
 impl WorkspaceLayout {
+    #[must_use]
     pub fn new(
         mode: LayoutMode,
         default_column_width: ColumnWidth,
@@ -61,6 +62,7 @@ impl WorkspaceLayout {
         self
     }
 
+    #[must_use]
     pub fn mode(&self) -> LayoutMode {
         match self {
             Self::Scrolling(_) => LayoutMode::Scrolling,
@@ -68,6 +70,7 @@ impl WorkspaceLayout {
         }
     }
 
+    #[must_use]
     pub fn viewport_x(&self) -> Option<f64> {
         match self {
             Self::Scrolling(layout) => Some(layout.viewport_x()),
@@ -75,6 +78,7 @@ impl WorkspaceLayout {
         }
     }
 
+    #[must_use]
     pub fn preferred_window(&self) -> Option<WindowId> {
         match self {
             Self::Scrolling(layout) => layout.active_window(),
@@ -82,6 +86,7 @@ impl WorkspaceLayout {
         }
     }
 
+    #[must_use]
     pub fn contains(&self, window: WindowId) -> bool {
         match self {
             Self::Scrolling(layout) => layout.contains(window),
@@ -125,6 +130,7 @@ impl WorkspaceLayout {
         }
     }
 
+    #[must_use]
     pub fn tab_group(&self, window: WindowId) -> Option<ferese_layout::TabGroup> {
         match self {
             Self::Tree(tree) => tree.tab_group(window),
@@ -132,6 +138,7 @@ impl WorkspaceLayout {
         }
     }
 
+    #[must_use]
     pub fn adjacent_tab(&self, window: WindowId, previous: bool) -> Option<WindowId> {
         match self {
             Self::Tree(tree) => tree.adjacent_tab(window, previous),
@@ -445,6 +452,7 @@ impl Default for WorkspaceSet {
 }
 
 impl WorkspaceSet {
+    #[must_use]
     pub fn new(
         default_layout_mode: LayoutMode,
         default_column_width: ColumnWidth,
@@ -562,10 +570,12 @@ impl WorkspaceSet {
         }
     }
 
+    #[must_use]
     pub fn active_id(&self) -> WorkspaceId {
         self.active
     }
 
+    #[must_use]
     pub fn active(&self) -> &Workspace {
         self.workspaces
             .get(&self.active)
@@ -596,6 +606,7 @@ impl WorkspaceSet {
         Ok(visible_floating.or(self.active().fullscreen).or(focused))
     }
 
+    #[must_use]
     pub fn workspace(&self, id: WorkspaceId) -> Option<&Workspace> {
         self.workspaces.get(&id)
     }
@@ -608,10 +619,12 @@ impl WorkspaceSet {
         self.workspaces.values()
     }
 
+    #[must_use]
     pub fn workspace_for_window(&self, window: WindowId) -> Option<WorkspaceId> {
         self.window_workspaces.get(&window).copied()
     }
 
+    #[must_use]
     pub fn placement(&self, window: WindowId) -> Option<WindowPlacement> {
         self.placements.get(&window).copied()
     }
@@ -823,6 +836,7 @@ impl WorkspaceSet {
     }
 
     /// Reserve workspace identities in a pure topology plan without creating them.
+    #[must_use]
     pub fn next_workspace_id(&self) -> WorkspaceId {
         WorkspaceId(self.next_id)
     }
@@ -1210,10 +1224,12 @@ fn finite_or_zero(value: f64) -> f64 {
 }
 
 impl Workspace {
+    #[must_use]
     pub fn window_count(&self) -> usize {
         self.layout.window_ids().count() + self.floating.len()
     }
 
+    #[must_use]
     pub fn is_empty(&self) -> bool {
         self.layout.window_ids().next().is_none() && self.floating.is_empty()
     }
diff --git a/crates/ferese-core/src/workspace_policy.rs b/crates/ferese-core/src/workspace_policy.rs
index 3dc2f17..01a7a32 100644
--- a/crates/ferese-core/src/workspace_policy.rs
+++ b/crates/ferese-core/src/workspace_policy.rs
@@ -14,6 +14,7 @@ pub struct WorkspaceView {
 }
 
 impl OutputWorkspaceMap {
+    #[must_use]
     pub fn workspace_views(&self, workspaces: &WorkspaceSet) -> Vec<WorkspaceView> {
         self.workspace_views_iter(workspaces).collect()
     }
@@ -47,6 +48,7 @@ impl OutputWorkspaceMap {
             })
     }
 
+    #[must_use]
     pub fn ordered_workspace_ids<'a>(
         &'a self,
         workspaces: &'a WorkspaceSet,
@@ -56,6 +58,7 @@ impl OutputWorkspaceMap {
             .filter(|id| workspaces.workspace(*id).is_some())
     }
 
+    #[must_use]
     pub fn ordered_workspaces(
         &self,
         workspaces: &WorkspaceSet,
@@ -66,6 +69,7 @@ impl OutputWorkspaceMap {
 
     /// Out-of-range numeric selection resolves to the trailing spare. Looking
     /// up a gesture target never creates workspaces or changes history.
+    #[must_use]
     pub fn workspace_at(
         &self,
         workspaces: &WorkspaceSet,
diff --git a/crates/ferese-ipc/src/activities.rs b/crates/ferese-ipc/src/activities.rs
index 63c6f22..30e02ef 100644
--- a/crates/ferese-ipc/src/activities.rs
+++ b/crates/ferese-ipc/src/activities.rs
@@ -4,6 +4,7 @@ use serde::{Deserialize, Serialize};
 
 pub const VERSION: u32 = 1;
 
+#[must_use]
 pub fn now_ms() -> u64 {
     let mut time = libc::timespec {
         tv_sec: 0,
diff --git a/crates/ferese-ipc/src/events.rs b/crates/ferese-ipc/src/events.rs
index 0639df6..6e91c5e 100644
--- a/crates/ferese-ipc/src/events.rs
+++ b/crates/ferese-ipc/src/events.rs
@@ -63,6 +63,7 @@ impl Event {
 }
 
 impl Snapshot {
+    #[must_use]
     pub fn changes_since(&self, previous: &Self) -> Vec<Change> {
         let mut changes = Vec::new();
         if self.outputs != previous.outputs {
diff --git a/crates/ferese-ipc/src/frame.rs b/crates/ferese-ipc/src/frame.rs
index 8b0e94f..350cf1c 100644
--- a/crates/ferese-ipc/src/frame.rs
+++ b/crates/ferese-ipc/src/frame.rs
@@ -36,6 +36,7 @@ pub struct ResponseError {
 }
 
 impl Response {
+    #[must_use]
     pub fn success(id: u64, result: Value) -> Self {
         Self {
             version: VERSION,
diff --git a/crates/ferese-ipc/src/media.rs b/crates/ferese-ipc/src/media.rs
index ffa949b..75a803d 100644
--- a/crates/ferese-ipc/src/media.rs
+++ b/crates/ferese-ipc/src/media.rs
@@ -1,5 +1,6 @@
 use serde::{Deserialize, Serialize};
 
+#[must_use]
 pub fn now_us() -> u64 {
     let mut time = libc::timespec {
         tv_sec: 0,
@@ -79,6 +80,7 @@ impl Default for Player {
 }
 
 impl Player {
+    #[must_use]
     pub fn label(&self) -> &str {
         if self.title.is_empty() {
             &self.identity
@@ -87,6 +89,7 @@ impl Player {
         }
     }
 
+    #[must_use]
     pub fn can_toggle(&self) -> bool {
         self.can_control
             && if self.status == Playback::Playing {
@@ -96,6 +99,7 @@ impl Player {
             }
     }
 
+    #[must_use]
     pub fn position_at(&self, now_us: u64) -> Option<u64> {
         let mut position = self.position_us? as f64;
         if self.status == Playback::Playing && self.rate.is_finite() {
diff --git a/crates/ferese-ipc/src/xwayland.rs b/crates/ferese-ipc/src/xwayland.rs
index a8d9167..37f329b 100644
--- a/crates/ferese-ipc/src/xwayland.rs
+++ b/crates/ferese-ipc/src/xwayland.rs
@@ -17,6 +17,7 @@ pub enum State {
 }
 
 impl State {
+    #[must_use]
     pub fn is_inactive(self) -> bool {
         matches!(self, Self::Disabled | Self::Idle | Self::Stopped)
     }
@@ -51,6 +52,7 @@ impl Status {
         serde_json::from_value(value)
     }
 
+    #[must_use]
     pub fn to_value(&self) -> Value {
         match serde_json::to_value(self) {
             Ok(value) => value,
diff --git a/crates/ferese-layout/src/layout_tree.rs b/crates/ferese-layout/src/layout_tree.rs
index fcf9b6c..39bc6b9 100644
--- a/crates/ferese-layout/src/layout_tree.rs
+++ b/crates/ferese-layout/src/layout_tree.rs
@@ -63,6 +63,7 @@ pub struct Rect {
 }
 
 impl Rect {
+    #[must_use]
     pub const fn new(x: f64, y: f64, width: f64, height: f64) -> Self {
         Self {
             x,
@@ -165,14 +166,17 @@ pub struct LayoutTree {
 }
 
 impl LayoutTree {
+    #[must_use]
     pub fn root(&self) -> Option<NodeId> {
         self.root
     }
 
+    #[must_use]
     pub fn node(&self, id: NodeId) -> Option<&Node> {
         self.nodes.get(&id)
     }
 
+    #[must_use]
     pub fn contains(&self, window: WindowId) -> bool {
         self.windows.contains_key(&window)
     }
@@ -181,6 +185,7 @@ impl LayoutTree {
         self.windows.keys().copied()
     }
 
+    #[must_use]
     pub fn visible_window_count(&self) -> usize {
         fn count(tree: &LayoutTree, node: NodeId) -> usize {
             match tree.nodes.get(&node) {
@@ -197,6 +202,7 @@ impl LayoutTree {
         self.root.map_or(0, |root| count(self, root))
     }
 
+    #[must_use]
     pub fn preferred_window(&self) -> Option<WindowId> {
         let leaf = self.first_window(self.root?).ok()?;
         match self.nodes.get(&leaf)? {
@@ -424,10 +430,12 @@ impl LayoutTree {
         })
     }
 
+    #[must_use]
     pub fn tab_group(&self, window: WindowId) -> Option<TabGroup> {
         self.group_at(*self.parents.get(self.windows.get(&window)?)?)
     }
 
+    #[must_use]
     pub fn tab_groups(&self) -> Vec<TabGroup> {
         let mut groups: Vec<_> = self
             .nodes
@@ -438,6 +446,7 @@ impl LayoutTree {
         groups
     }
 
+    #[must_use]
     pub fn adjacent_tab(&self, window: WindowId, previous: bool) -> Option<WindowId> {
         let group = self.tab_group(window)?;
         let index = group.windows.iter().position(|id| *id == window)?;
diff --git a/crates/ferese-layout/src/scrolling.rs b/crates/ferese-layout/src/scrolling.rs
index 160a37a..4c93d8e 100644
--- a/crates/ferese-layout/src/scrolling.rs
+++ b/crates/ferese-layout/src/scrolling.rs
@@ -90,13 +90,15 @@ impl Column {
         if self.heights.len() != self.windows.len() {
             self.heights.resize(self.windows.len(), 1.0);
         }
-        self.heights.iter_mut().for_each(|height| {
+        for height in &mut self.heights {
             if !height.is_finite() || *height <= 0.0 {
                 *height = 1.0;
             }
-        });
+        }
         let total = self.heights.iter().sum::<f64>();
-        self.heights.iter_mut().for_each(|height| *height /= total);
+        for height in &mut self.heights {
+            *height /= total;
+        }
         self.active = self.active.min(self.windows.len() - 1);
     }
 }
@@ -166,6 +168,7 @@ impl ViewportTarget {
 
     /// Re-evaluate the same target with pending allocated widths held back.
     /// A start-relative request can also use the previous held target.
+    #[must_use]
     pub fn with_held_widths(&self, widths: &[(WindowId, f64, f64)], start: Option<f64>) -> f64 {
         let replacements = widths
             .iter()
@@ -181,6 +184,7 @@ impl ViewportTarget {
         self.target(&replacements, start)
     }
 
+    #[must_use]
     pub fn uses_previous_target(&self) -> bool {
         matches!(self.request, ViewportRequest::Slide(..))
             || (matches!(self.request, ViewportRequest::Reveal(..))
@@ -290,6 +294,7 @@ impl ScrollingLayout {
         Ok(())
     }
 
+    #[must_use]
     pub fn tab_group(&self, window: WindowId) -> Option<crate::TabGroup> {
         let (index, _) = self.window_location(window)?;
         let column = &self.columns[index];
@@ -301,6 +306,7 @@ impl ScrollingLayout {
         })
     }
 
+    #[must_use]
     pub fn adjacent_tab(&self, window: WindowId, previous: bool) -> Option<WindowId> {
         let group = self.tab_group(window)?;
         let index = group.windows.iter().position(|id| *id == window)?;
@@ -308,6 +314,7 @@ impl ScrollingLayout {
         Some(group.windows[(index + step) % group.windows.len()])
     }
 
+    #[must_use]
     pub fn visible_window_count(&self) -> usize {
         self.columns
             .iter()
@@ -325,6 +332,7 @@ impl ScrollingLayout {
         self.default_width = normalized_width(width);
     }
 
+    #[must_use]
     pub fn with_default_width(default_width: ColumnWidth) -> Self {
         Self {
             default_width: normalized_width(default_width),
@@ -337,33 +345,40 @@ impl ScrollingLayout {
         self.request_focus(self.active_window().map(PendingFocusRequest::Reveal));
     }
 
+    #[must_use]
     pub fn default_width(&self) -> ColumnWidth {
         self.default_width
     }
 
+    #[must_use]
     pub fn columns(&self) -> &[Column] {
         &self.columns
     }
 
+    #[must_use]
     pub fn active_column(&self) -> Option<usize> {
         self.active_column
     }
 
+    #[must_use]
     pub fn active_window(&self) -> Option<WindowId> {
         let column = self.columns.get(self.active_column?)?;
         column.windows.get(column.active).copied()
     }
 
+    #[must_use]
     pub fn viewport_x(&self) -> f64 {
         self.viewport_x
     }
 
+    #[must_use]
     pub fn allocated_column_width(&self, window: WindowId) -> Option<f64> {
         self.allocated_widths.get(&window).copied()
     }
 
     /// Whether this target changes when the pending column width is held back.
     /// Allocated widths, rather than cell-grid/native buffer sizes, own the strip.
+    #[must_use]
     pub fn viewport_depends_on_width(&self, window: WindowId, source: f64, target: f64) -> bool {
         (source - target).abs() > 0.001
             && self
@@ -373,6 +388,7 @@ impl ScrollingLayout {
                 .is_some_and(|held| (held - self.viewport_x).abs() > 0.001)
     }
 
+    #[must_use]
     pub fn viewport_target(&self) -> Option<&ViewportTarget> {
         self.viewport_basis.as_ref()
     }
@@ -400,6 +416,7 @@ impl ScrollingLayout {
         self.viewport_basis = Some(next);
     }
 
+    #[must_use]
     pub fn contains(&self, window: WindowId) -> bool {
         self.window_location(window).is_some()
     }
diff --git a/crates/ferese-panel/src/adaptive.rs b/crates/ferese-panel/src/adaptive.rs
index 15a86e9..6dd8a78 100644
--- a/crates/ferese-panel/src/adaptive.rs
+++ b/crates/ferese-panel/src/adaptive.rs
@@ -18,6 +18,7 @@ pub enum Presentation {
 }
 
 impl Presentation {
+    #[must_use]
     pub fn style(self) -> Option<PanelStyle> {
         match self {
             Self::Floating => Some(PanelStyle::Floating),
@@ -48,6 +49,7 @@ pub struct Adaptive {
 }
 
 impl Adaptive {
+    #[must_use]
     pub fn new(state: WindowState) -> Self {
         Self {
             current: state.into(),
@@ -55,6 +57,7 @@ impl Adaptive {
         }
     }
 
+    #[must_use]
     pub fn current(&self) -> Presentation {
         self.current
     }
@@ -87,6 +90,7 @@ impl Adaptive {
         }
     }
 
+    #[must_use]
     pub fn deadline(&self) -> Option<Duration> {
         self.pending
             .map(|(_, since)| since.saturating_add(HYSTERESIS))
diff --git a/crates/ferese-panel/src/lib.rs b/crates/ferese-panel/src/lib.rs
index 9162337..14031a8 100644
--- a/crates/ferese-panel/src/lib.rs
+++ b/crates/ferese-panel/src/lib.rs
@@ -9,6 +9,7 @@ pub mod shape;
 
 pub use shape::Style as PanelStyle;
 
+#[must_use]
 pub const fn default_island_padding() -> f32 {
     4.0
 }
diff --git a/crates/ferese-panel/src/morph.rs b/crates/ferese-panel/src/morph.rs
index 9573e81..b4f4621 100644
--- a/crates/ferese-panel/src/morph.rs
+++ b/crates/ferese-panel/src/morph.rs
@@ -75,6 +75,7 @@ impl Profile {
         }
     }
 
+    #[must_use]
     pub fn size(self, mode: Mode, collapsed_height: f64) -> [f64; 2] {
         match mode {
             Mode::Idle => [self.idle_width, collapsed_height],
@@ -114,6 +115,7 @@ pub enum Mode {
 }
 
 impl Mode {
+    #[must_use]
     pub fn expanded(self) -> bool {
         matches!(self, Self::Expanded(_))
     }
@@ -145,7 +147,7 @@ pub struct Hub {
 }
 
 impl Hub {
-    pub fn new(profile: Profile, collapsed_height: f64) -> Result<Self, &'static str> {
+    pub fn try_new(profile: Profile, collapsed_height: f64) -> Result<Self, &'static str> {
         profile.validate()?;
         if !collapsed_height.is_finite() || !(24. ..=128.).contains(&collapsed_height) {
             return Err("hub height must be 24..128");
@@ -196,6 +198,7 @@ impl Hub {
         self.motion.retarget(target)
     }
 
+    #[must_use]
     pub fn mode(&self) -> Mode {
         self.mode
     }
@@ -301,10 +304,12 @@ impl Hub {
         self.active()
     }
 
+    #[must_use]
     pub fn active(&self) -> bool {
         self.motion.active() || self.sample().previous_opacity > 0. || self.sample().opacity < 1.
     }
 
+    #[must_use]
     pub fn sample(&self) -> Sample {
         let fade = |elapsed: Duration| (elapsed.as_secs_f32() / FADE.as_secs_f32()).clamp(0., 1.);
         let opacity = self.initial_opacity
@@ -324,11 +329,13 @@ impl Hub {
         }
     }
 
+    #[must_use]
     pub fn allocation_size(&self) -> [f64; 2] {
         let maximum = self.motion.maximum_size();
         std::array::from_fn(|i| maximum[i].min(self.available[i]))
     }
 
+    #[must_use]
     pub fn target_size(&self) -> [f64; 2] {
         let target = self.motion.target().bounds;
         [target.width, target.height]
@@ -341,7 +348,7 @@ mod tests {
 
     #[test]
     fn workspace_width_changes_preserve_content_and_motion() {
-        let mut hub = Hub::new(Profile::default(), 34.).unwrap();
+        let mut hub = Hub::try_new(Profile::default(), 34.).unwrap();
         hub.retarget_idle(270., [800., 600.]).unwrap();
         hub.advance(Duration::from_millis(60), false);
         let before = hub.sample();
@@ -358,7 +365,7 @@ mod tests {
 
     #[test]
     fn measured_height_preserves_fade_and_motion_and_caps_long_content() {
-        let mut hub = Hub::new(Profile::default(), 34.).unwrap();
+        let mut hub = Hub::try_new(Profile::default(), 34.).unwrap();
         hub.retarget(Mode::Expanded(Content::Controls), [800., 600.])
             .unwrap();
         hub.advance(Duration::from_millis(180), false);
@@ -382,7 +389,7 @@ mod tests {
 
     #[test]
     fn a_content_swap_fades_without_restarting_the_geometry() {
-        let mut hub = Hub::new(Profile::default(), 34.).unwrap();
+        let mut hub = Hub::try_new(Profile::default(), 34.).unwrap();
         hub.retarget(Mode::Expanded(Content::Controls), [800., 600.])
             .unwrap();
         hub.advance(Duration::from_secs(2), false);
@@ -404,7 +411,7 @@ mod tests {
 
     #[test]
     fn content_swap_uses_a_fixed_delay_instead_of_waiting_for_spring_settlement() {
-        let mut hub = Hub::new(Profile::default(), 34.).unwrap();
+        let mut hub = Hub::try_new(Profile::default(), 34.).unwrap();
         assert!(!hub.active());
         hub.retarget(Mode::Expanded(Content::Calendar), [800., 600.])
             .unwrap();
@@ -430,7 +437,7 @@ mod tests {
 
     #[test]
     fn an_interrupted_content_delay_never_reveals_the_cancelled_panel() {
-        let mut hub = Hub::new(Profile::default(), 34.).unwrap();
+        let mut hub = Hub::try_new(Profile::default(), 34.).unwrap();
         hub.retarget(Mode::Expanded(Content::Media), [800., 600.])
             .unwrap();
         hub.advance(Duration::from_millis(80), false);
@@ -448,7 +455,7 @@ mod tests {
 
     #[test]
     fn spring_overshoots_then_settles_within_its_reserved_surface() {
-        let mut hub = Hub::new(Profile::default(), 34.).unwrap();
+        let mut hub = Hub::try_new(Profile::default(), 34.).unwrap();
         hub.retarget(Mode::Expanded(Content::Calendar), [800., 600.])
             .unwrap();
         let allocation = hub.allocation_size();
@@ -468,7 +475,7 @@ mod tests {
 
     #[test]
     fn overshoot_is_clipped_to_small_outputs_and_reduced_motion_removes_all_fades() {
-        let mut hub = Hub::new(Profile::default(), 34.).unwrap();
+        let mut hub = Hub::try_new(Profile::default(), 34.).unwrap();
         hub.retarget(Mode::Expanded(Content::Calendar), [240., 180.])
             .unwrap();
         for _ in 0..60 {
@@ -486,7 +493,7 @@ mod tests {
 
     #[test]
     fn interrupted_expansion_keeps_the_presented_shape() {
-        let mut hub = Hub::new(Profile::default(), 34.).unwrap();
+        let mut hub = Hub::try_new(Profile::default(), 34.).unwrap();
         hub.retarget(Mode::Expanded(Content::Media), [800., 600.])
             .unwrap();
         hub.advance(Duration::from_millis(40), false);
@@ -502,7 +509,7 @@ mod tests {
 
     #[test]
     fn narrow_outputs_and_reduced_motion_keep_the_hub_bounded() {
-        let mut hub = Hub::new(Profile::default(), 30.).unwrap();
+        let mut hub = Hub::try_new(Profile::default(), 30.).unwrap();
         hub.retarget(Mode::Expanded(Content::Calendar), [240., 180.])
             .unwrap();
         hub.advance(Duration::ZERO, true);
diff --git a/crates/ferese-panel/src/motion.rs b/crates/ferese-panel/src/motion.rs
index b0c4911..1cd5d8e 100644
--- a/crates/ferese-panel/src/motion.rs
+++ b/crates/ferese-panel/src/motion.rs
@@ -18,6 +18,7 @@ pub struct Geometry {
 const COUNT: usize = 18;
 
 impl Geometry {
+    #[must_use]
     pub fn rounded(bounds: Rect, radius: f64) -> Self {
         Self {
             bounds,
@@ -75,7 +76,7 @@ pub struct Motion {
 }
 
 impl Motion {
-    pub fn new(geometry: Geometry) -> Result<Self, &'static str> {
+    pub fn try_new(geometry: Geometry) -> Result<Self, &'static str> {
         Self::with_spring(
             geometry,
             SpringConfig {
@@ -132,10 +133,12 @@ impl Motion {
         })
     }
 
+    #[must_use]
     pub fn current(&self) -> Geometry {
         Geometry::from_values(self.values.map(|value| value.current))
     }
 
+    #[must_use]
     pub fn target(&self) -> Geometry {
         Geometry::from_values(self.values.map(|value| value.target))
     }
@@ -180,7 +183,7 @@ mod tests {
 
     #[test]
     fn interruption_keeps_the_current_geometry_and_velocity() {
-        let mut motion = Motion::new(collapsed()).unwrap();
+        let mut motion = Motion::try_new(collapsed()).unwrap();
         motion.retarget(expanded()).unwrap();
         motion.advance(Duration::from_millis(16), false);
         let before = motion.current();
@@ -197,7 +200,7 @@ mod tests {
 
     #[test]
     fn dimensions_share_one_trajectory_and_stop_requesting_frames() {
-        let mut motion = Motion::new(collapsed()).unwrap();
+        let mut motion = Motion::try_new(collapsed()).unwrap();
         motion.retarget(expanded()).unwrap();
         for _ in 0..12 {
             motion.advance(Duration::from_millis(16), false);
@@ -218,7 +221,7 @@ mod tests {
 
     #[test]
     fn reduced_motion_snaps_an_inflight_animation() {
-        let mut motion = Motion::new(collapsed()).unwrap();
+        let mut motion = Motion::try_new(collapsed()).unwrap();
         motion.retarget(expanded()).unwrap();
         motion.advance(Duration::from_millis(16), false);
         assert!(!motion.advance(Duration::ZERO, true));
@@ -263,7 +266,7 @@ mod tests {
 
     #[test]
     fn invalid_retarget_leaves_motion_untouched() {
-        let mut motion = Motion::new(collapsed()).unwrap();
+        let mut motion = Motion::try_new(collapsed()).unwrap();
         let mut invalid = expanded();
         invalid.bounds.height = f64::NAN;
         assert!(motion.retarget(invalid).is_err());
diff --git a/crates/ferese-panel/src/outline.rs b/crates/ferese-panel/src/outline.rs
index 5f0ef6a..6285ecc 100644
--- a/crates/ferese-panel/src/outline.rs
+++ b/crates/ferese-panel/src/outline.rs
@@ -269,7 +269,7 @@ mod tests {
                         zone: ZonePosition::Center,
                         bounds: Rect::new(70.3, 0., 160.4, 44.),
                     }],
-                    PixelGrid::new(scale).unwrap(),
+                    PixelGrid::try_new(scale).unwrap(),
                 )
                 .unwrap();
                 let paths = notch_border(&scene, 0.1 / scale, edge).unwrap();
@@ -325,7 +325,7 @@ mod tests {
                         },
                         Rect::new(30.3, 0., width, height),
                         &[],
-                        PixelGrid::new(scale).unwrap(),
+                        PixelGrid::try_new(scale).unwrap(),
                     )
                     .unwrap();
                     let body = scene.paint[0];
@@ -420,7 +420,7 @@ mod tests {
                 },
                 Rect::new(0., 0., 96., 64.),
                 &groups,
-                PixelGrid::new(1.25).unwrap(),
+                PixelGrid::try_new(1.25).unwrap(),
             )
             .unwrap();
             let contours = contours(&scene, 0.1).unwrap();
diff --git a/crates/ferese-panel/src/panel/composition.rs b/crates/ferese-panel/src/panel/composition.rs
index 0357066..d10c3a8 100644
--- a/crates/ferese-panel/src/panel/composition.rs
+++ b/crates/ferese-panel/src/panel/composition.rs
@@ -33,6 +33,7 @@ pub enum Edge {
 }
 
 impl Edge {
+    #[must_use]
     pub fn key(self) -> &'static str {
         match self {
             Self::Top => "top",
@@ -86,6 +87,7 @@ impl WorkspaceStyle {
         Self::AppIcons,
     ];
 
+    #[must_use]
     pub fn key(self) -> &'static str {
         match self {
             Self::Numbers => "numbers",
@@ -96,6 +98,7 @@ impl WorkspaceStyle {
         }
     }
 
+    #[must_use]
     pub fn label(self) -> &'static str {
         match self {
             Self::Numbers => "Numbers",
@@ -135,6 +138,7 @@ pub enum ItemKind {
 
 impl ItemKind {
     /// Smallest useful allocation before a flexible control moves into overflow.
+    #[must_use]
     pub fn minimum_width(self) -> Option<f32> {
         match self {
             Self::FocusedWindow => Some(48.),
@@ -144,6 +148,7 @@ impl ItemKind {
         }
     }
 
+    #[must_use]
     pub fn label(self) -> &'static str {
         match self {
             Self::Overview => "Overview",
@@ -163,6 +168,7 @@ impl ItemKind {
             Self::Overflow => "Overflow",
         }
     }
+    #[must_use]
     pub fn representations(self) -> &'static [Representation] {
         use Representation::*;
         match self {
@@ -265,6 +271,7 @@ impl<'de> Deserialize<'de> for Item {
 
 impl Item {
     /// Start at the configured preference and retain supported smaller forms.
+    #[must_use]
     pub fn representations(&self) -> Vec<Representation> {
         let supported = self.kind.representations();
         let preferred = self.representation.unwrap_or(supported[0]);
@@ -279,6 +286,7 @@ impl Item {
             alternatives
         }
     }
+    #[must_use]
     pub fn new(id: &str, kind: ItemKind) -> Self {
         Self {
             id: ItemId(id.into()),
@@ -305,6 +313,7 @@ impl Item {
         }
     }
 
+    #[must_use]
     pub fn available(&self, availability: Availability) -> bool {
         if !self.visible {
             return false;
@@ -351,6 +360,7 @@ pub enum GroupSurface {
 }
 
 impl GroupSurface {
+    #[must_use]
     pub fn key(self) -> &'static str {
         match self {
             Self::None => "none",
@@ -519,6 +529,7 @@ impl Default for Panel {
 }
 
 impl Panel {
+    #[must_use]
     pub fn preset(&self) -> Option<PanelStyle> {
         Some(self.style)
     }
@@ -527,6 +538,7 @@ impl Panel {
         self.style = style;
     }
 
+    #[must_use]
     pub fn surface(&self) -> PanelSurface {
         if matches!(self.style, PanelStyle::Flat | PanelStyle::Frame) {
             PanelSurface::Solid
@@ -535,6 +547,7 @@ impl Panel {
         }
     }
 
+    #[must_use]
     pub fn group_surface(&self) -> GroupSurface {
         if self.surface() == PanelSurface::Solid {
             GroupSurface::None
@@ -543,6 +556,7 @@ impl Panel {
         }
     }
 
+    #[must_use]
     pub fn zone_spacing(&self, zone: &Zone) -> f32 {
         if self.style.connected() {
             0.
@@ -551,6 +565,7 @@ impl Panel {
         }
     }
 
+    #[must_use]
     pub fn shape_parameters(&self) -> crate::scene::Parameters {
         crate::scene::Parameters {
             style: self.style,
@@ -567,6 +582,7 @@ impl Panel {
         }
     }
 
+    #[must_use]
     pub fn resolved_geometry(&self) -> PanelGeometry {
         let mut geometry = self.geometry.resolve(self.style);
         if self.style == PanelStyle::Morph && self.morph.attached {
@@ -575,6 +591,7 @@ impl Panel {
         geometry
     }
 
+    #[must_use]
     pub fn exclusive_zone(&self, hidden: bool) -> i32 {
         if hidden {
             0
@@ -584,6 +601,7 @@ impl Panel {
         }
     }
 
+    #[must_use]
     pub fn group_count(&self) -> usize {
         [&self.start, &self.center, &self.end]
             .into_iter()
@@ -592,6 +610,7 @@ impl Panel {
     }
 
     /// Appearance changes do not replace item ownership or measured allocation.
+    #[must_use]
     pub fn same_composition(&self, other: &Self) -> bool {
         let same_zone = |left: &Zone, right: &Zone| {
             left.spacing == right.spacing
@@ -615,12 +634,14 @@ impl Panel {
             && same_zone(&self.end, &other.end)
     }
 
+    #[must_use]
     pub fn resolved_radius(&self, shell_radius: f32) -> CornerRadii {
         self.corner_radius
             .unwrap_or_else(|| CornerRadii::uniform(shell_radius))
     }
 
     /// The overflow trigger is generated, never persisted as a configured item.
+    #[must_use]
     pub fn overflow_group(&self) -> Group {
         Group {
             id: GroupId("_overflow".into()),
@@ -646,6 +667,7 @@ impl Panel {
         }
     }
 
+    #[must_use]
     pub fn item(&self, id: &ItemId) -> Option<&Item> {
         [&self.start, &self.center, &self.end]
             .into_iter()
@@ -655,6 +677,7 @@ impl Panel {
     }
 
     /// Build a stable initial composition; presets are an editor convenience.
+    #[must_use]
     pub fn from_preset(preset: PanelStyle) -> Self {
         use ItemKind::*;
 
diff --git a/crates/ferese-panel/src/panel/geometry.rs b/crates/ferese-panel/src/panel/geometry.rs
index f1e6213..be0afd2 100644
--- a/crates/ferese-panel/src/panel/geometry.rs
+++ b/crates/ferese-panel/src/panel/geometry.rs
@@ -16,6 +16,7 @@ pub struct GeometryIntent {
 }
 
 impl GeometryIntent {
+    #[must_use]
     pub fn resolve(self, style: crate::PanelStyle) -> PanelGeometry {
         use crate::PanelStyle::*;
         let flush = matches!(style, Notch | Flat | Frame | CornerWrap);
diff --git a/crates/ferese-panel/src/panel/layout.rs b/crates/ferese-panel/src/panel/layout.rs
index 298ba6f..a29ca69 100644
--- a/crates/ferese-panel/src/panel/layout.rs
+++ b/crates/ferese-panel/src/panel/layout.rs
@@ -92,12 +92,14 @@ impl Resolution {
         }
     }
 
+    #[must_use]
     pub fn fits(&self, available: f32) -> bool {
         self.required_width() <= available
     }
 
     /// Clamp a requested inset independently for each output. Content may still
     /// overflow on an output too small to fit it even without an inset.
+    #[must_use]
     pub fn side_margin(&self, requested: i32, output_width: i32, padding: f32) -> i32 {
         let maximum = ((output_width as f32 - 2. * padding - self.minimum_width) / 2.)
             .floor()
@@ -106,6 +108,7 @@ impl Resolution {
     }
 }
 
+#[must_use]
 pub fn resolve(
     panel: &Panel,
     measurements: &[Measurement],
@@ -116,6 +119,7 @@ pub fn resolve(
 }
 
 /// Reserve separation between zones while keeping the center on the panel midpoint.
+#[must_use]
 pub fn resolve_with_gap(
     panel: &Panel,
     measurements: &[Measurement],
diff --git a/crates/ferese-panel/src/panel/radius.rs b/crates/ferese-panel/src/panel/radius.rs
index 21b71f5..93bcd74 100644
--- a/crates/ferese-panel/src/panel/radius.rs
+++ b/crates/ferese-panel/src/panel/radius.rs
@@ -5,6 +5,7 @@ use serde::{Deserialize, Deserializer, Serialize, Serializer};
 pub struct CornerRadii(pub [f32; 4]);
 
 impl CornerRadii {
+    #[must_use]
     pub fn uniform(radius: f32) -> Self {
         Self([radius; 4])
     }
@@ -18,6 +19,7 @@ impl CornerRadii {
     }
 
     /// A panel touching the top edge must cover its top corners.
+    #[must_use]
     pub fn at_top_edge(mut self, touching: bool) -> Self {
         if touching {
             self.0[0] = 0.;
@@ -26,6 +28,7 @@ impl CornerRadii {
         self
     }
 
+    #[must_use]
     pub fn at_edge(mut self, edge: super::Edge, touching: bool) -> Self {
         if touching {
             match edge {
@@ -44,6 +47,7 @@ impl CornerRadii {
     }
 
     /// Keep every corner within half the shorter surface dimension.
+    #[must_use]
     pub fn clamped(self, width: f32, height: f32) -> Self {
         let limit = width.min(height).max(0.) / 2.;
         Self(self.0.map(|value| value.min(limit)))
@@ -52,6 +56,7 @@ impl CornerRadii {
     /// Scale all corners together when their sums exceed an adjacent edge.
     /// Unlike the symmetric round-box clamp, this permits a large free-side
     /// corner when the corner on the anchored side is square.
+    #[must_use]
     pub fn normalized(self, width: f32, height: f32) -> Self {
         let [tl, tr, br, bl] = self.0;
         let mut factor = 1.0_f64;
diff --git a/crates/ferese-panel/src/scene.rs b/crates/ferese-panel/src/scene.rs
index c8c6ded..71852e7 100644
--- a/crates/ferese-panel/src/scene.rs
+++ b/crates/ferese-panel/src/scene.rs
@@ -16,6 +16,7 @@ pub struct Primitive {
 }
 
 impl Primitive {
+    #[must_use]
     pub fn packet(self) -> [f32; 10] {
         let Rect {
             x,
@@ -66,6 +67,7 @@ impl Primitive {
         })
     }
 
+    #[must_use]
     pub fn distance(self, point: [f64; 2]) -> f64 {
         let rect = rectangle_distance(point, self.bounds);
         if self.operation >= 2 {
@@ -103,6 +105,7 @@ fn rectangle_distance(point: [f64; 2], b: Rect) -> f64 {
     x.max(0.).hypot(y.max(0.)) + x.max(y).min(0.)
 }
 
+#[must_use]
 pub fn smooth_min(a: f64, b: f64, strength: f64) -> f64 {
     if strength <= 0. {
         return a.min(b);
@@ -141,16 +144,19 @@ impl Scene {
         zones.into_iter().fold(f64::INFINITY, f64::min).max(-cutout)
     }
 
+    #[must_use]
     pub fn contains(&self, point: [f64; 2]) -> bool {
         self.input.iter().any(|shape| shape.contains(point))
     }
 
+    #[must_use]
     pub fn packets(&self) -> Vec<[f32; 10]> {
         self.paint.iter().map(|p| p.packet()).collect()
     }
 
     /// Horizontal runs at physical-pixel centers. Corners and animated gaps
     /// stay click-through; adjacent equal runs are coalesced into one rectangle.
+    #[must_use]
     pub fn input_rectangles(&self, scale: f64) -> Vec<[i32; 4]> {
         if !scale.is_finite() || scale <= 0. {
             return Vec::new();
@@ -246,7 +252,7 @@ fn add(
     input: bool,
     zone: u8,
 ) -> Result<(), &'static str> {
-    let rounded = RoundedSurface::new(rect, radii, grid)?;
+    let rounded = RoundedSurface::try_new(rect, radii, grid)?;
     if rounded.bounds().width == 0. || rounded.bounds().height == 0. {
         return Ok(());
     }
@@ -320,7 +326,7 @@ pub fn derive(
                 operation: 1,
                 blend_zone: 0,
             });
-            scene.input.push(RoundedSurface::new(
+            scene.input.push(RoundedSurface::try_new(
                 Rect::new(bounds.x, bounds.y, bounds.width, top),
                 CornerRadii::uniform(0.),
                 grid,
@@ -583,8 +589,11 @@ pub fn derive(
         }
         for input in &mut scene.input {
             let [tl, tr, br, bl] = input.radii().0;
-            *input =
-                RoundedSurface::new(mirror(input.bounds()), CornerRadii([bl, br, tr, tl]), grid)?;
+            *input = RoundedSurface::try_new(
+                mirror(input.bounds()),
+                CornerRadii([bl, br, tr, tl]),
+                grid,
+            )?;
         }
         for damage in &mut scene.damage {
             *damage = mirror(*damage);
@@ -624,7 +633,7 @@ mod tests {
             },
             Rect::new(0., 0., 800., 36.),
             &groups(),
-            PixelGrid::new(1.25).unwrap(),
+            PixelGrid::try_new(1.25).unwrap(),
         )
         .unwrap()
     }
@@ -677,7 +686,7 @@ mod tests {
             },
             Rect::new(0., 0., 800., 600.),
             &[],
-            PixelGrid::new(1.25).unwrap(),
+            PixelGrid::try_new(1.25).unwrap(),
         )
         .unwrap();
         assert!(scene.contains([18., 200.]));
@@ -714,7 +723,7 @@ mod tests {
             },
             Rect::new(0., 0., 1600., 1000.),
             &[],
-            PixelGrid::new(1.5).unwrap(),
+            PixelGrid::try_new(1.5).unwrap(),
         )
         .unwrap();
         assert!(scene.distance([800., 20.]) < 0. && scene.distance([800., 500.]) > 0.);
@@ -746,7 +755,7 @@ mod tests {
     fn attached_styles_mirror_the_whole_outline_at_the_bottom() {
         for style in [Style::Notch, Style::Frame, Style::CornerWrap] {
             let bounds = Rect::new(0., 0., 800., if style == Style::Notch { 36. } else { 600. });
-            let grid = PixelGrid::new(1.).unwrap();
+            let grid = PixelGrid::try_new(1.).unwrap();
             let top = derive(
                 Parameters {
                     style,
diff --git a/crates/ferese-panel/src/shape.rs b/crates/ferese-panel/src/shape.rs
index cbe245a..3fd9dd8 100644
--- a/crates/ferese-panel/src/shape.rs
+++ b/crates/ferese-panel/src/shape.rs
@@ -43,6 +43,7 @@ impl Style {
         Self::WindowHug,
     ];
 
+    #[must_use]
     pub const fn key(self) -> &'static str {
         match self {
             Self::Floating => "floating",
@@ -57,6 +58,7 @@ impl Style {
             Self::WindowHug => "window-hug",
         }
     }
+    #[must_use]
     pub const fn label(self) -> &'static str {
         match self {
             Self::Floating => "Floating",
@@ -71,9 +73,11 @@ impl Style {
             Self::WindowHug => "Window hug",
         }
     }
+    #[must_use]
     pub const fn connected(self) -> bool {
         matches!(self, Self::Capsules | Self::Notch)
     }
+    #[must_use]
     pub const fn detached(self) -> bool {
         matches!(
             self,
@@ -100,6 +104,7 @@ pub enum ZonePosition {
 pub struct AnchoredRadii(pub [f32; 4]);
 
 impl AnchoredRadii {
+    #[must_use]
     pub fn screen_space(self, edge: Edge) -> CornerRadii {
         let [flat_left, flat_right, free_right, free_left] = self.0;
         CornerRadii(match edge {
@@ -173,13 +178,14 @@ pub struct PixelGrid {
 }
 
 impl PixelGrid {
-    pub fn new(scale: f64) -> Result<Self, &'static str> {
+    pub fn try_new(scale: f64) -> Result<Self, &'static str> {
         if !scale.is_finite() || scale <= 0. {
             return Err("output scale must be finite and positive");
         }
         Ok(Self { scale })
     }
 
+    #[must_use]
     pub fn snap(self, position: f64) -> f64 {
         (position * self.scale).round() / self.scale
     }
@@ -218,7 +224,11 @@ pub struct RoundedSurface {
 }
 
 impl RoundedSurface {
-    pub fn new(bounds: Rect, radii: CornerRadii, grid: PixelGrid) -> Result<Self, &'static str> {
+    pub fn try_new(
+        bounds: Rect,
+        radii: CornerRadii,
+        grid: PixelGrid,
+    ) -> Result<Self, &'static str> {
         if radii.validate().is_err() {
             return Err("surface radii must be finite and nonnegative");
         }
@@ -230,16 +240,19 @@ impl RoundedSurface {
         Ok(Self { bounds, radii })
     }
 
+    #[must_use]
     pub fn bounds(self) -> Rect {
         self.bounds
     }
 
+    #[must_use]
     pub fn radii(self) -> CornerRadii {
         self.radii
     }
 
     /// Right and bottom boundaries are excluded so a shared seam belongs to
     /// exactly one surface, rather than both neighbors.
+    #[must_use]
     pub fn contains(self, point: [f64; 2]) -> bool {
         let [x, y] = [point[0] - self.bounds.x, point[1] - self.bounds.y];
         let (width, height) = (self.bounds.width, self.bounds.height);
@@ -339,7 +352,7 @@ mod tests {
     #[test]
     fn shared_boundaries_snap_without_seams_at_fractional_scales() {
         for scale in [1., 1.25, 1.5, 2.] {
-            let grid = PixelGrid::new(scale).unwrap();
+            let grid = PixelGrid::try_new(scale).unwrap();
             for origin in [-1800.3, -0.4, 0., 23.3] {
                 let left = grid.rect(Rect::new(origin, 0., 33.3, 36.)).unwrap();
                 let right = grid.rect(Rect::new(origin + 33.3, 0., 42.7, 36.)).unwrap();
@@ -353,14 +366,14 @@ mod tests {
 
     #[test]
     fn floating_gaps_and_round_corners_do_not_capture_input() {
-        let grid = PixelGrid::new(1.25).unwrap();
-        let left = RoundedSurface::new(
+        let grid = PixelGrid::try_new(1.25).unwrap();
+        let left = RoundedSurface::try_new(
             Rect::new(8., 8., 100., 36.),
             CornerRadii::uniform(18.),
             grid,
         )
         .unwrap();
-        let right = RoundedSurface::new(
+        let right = RoundedSurface::try_new(
             Rect::new(116., 8., 100., 36.),
             CornerRadii::uniform(18.),
             grid,
@@ -381,15 +394,15 @@ mod tests {
 
     #[test]
     fn asymmetric_hit_testing_matches_a_vertically_mirrored_surface() {
-        let grid = PixelGrid::new(1.).unwrap();
+        let grid = PixelGrid::try_new(1.).unwrap();
         let bounds = Rect::new(0., 0., 100., 28.);
-        let top = RoundedSurface::new(
+        let top = RoundedSurface::try_new(
             bounds,
             AnchoredRadii([0., 0., 20., 20.]).screen_space(Edge::Top),
             grid,
         )
         .unwrap();
-        let bottom = RoundedSurface::new(
+        let bottom = RoundedSurface::try_new(
             bounds,
             AnchoredRadii([0., 0., 20., 20.]).screen_space(Edge::Bottom),
             grid,
@@ -409,14 +422,14 @@ mod tests {
 
     #[test]
     fn a_connected_seam_has_exactly_one_input_owner() {
-        let grid = PixelGrid::new(1.5).unwrap();
-        let left = RoundedSurface::new(
+        let grid = PixelGrid::try_new(1.5).unwrap();
+        let left = RoundedSurface::try_new(
             Rect::new(0., 0., 30., 36.),
             CornerRadii([18., 0., 0., 18.]),
             grid,
         )
         .unwrap();
-        let right = RoundedSurface::new(
+        let right = RoundedSurface::try_new(
             Rect::new(30., 0., 40., 36.),
             CornerRadii([0., 18., 18., 0.]),
             grid,
@@ -431,9 +444,9 @@ mod tests {
     #[test]
     fn invalid_runtime_geometry_is_rejected() {
         for scale in [0., -1., f64::NAN, f64::INFINITY] {
-            assert!(PixelGrid::new(scale).is_err());
+            assert!(PixelGrid::try_new(scale).is_err());
         }
-        let grid = PixelGrid::new(1.).unwrap();
+        let grid = PixelGrid::try_new(1.).unwrap();
         for bounds in [
             Rect::new(0., 0., -1., 28.),
             Rect::new(f64::NAN, 0., 10., 28.),
@@ -442,7 +455,7 @@ mod tests {
             assert!(grid.rect(bounds).is_err());
         }
         assert!(
-            RoundedSurface::new(Rect::new(0., 0., 10., 28.), CornerRadii::uniform(-1.), grid)
+            RoundedSurface::try_new(Rect::new(0., 0., 10., 28.), CornerRadii::uniform(-1.), grid)
                 .is_err()
         );
         assert!(
diff --git a/crates/ferese-theme-client/src/service.rs b/crates/ferese-theme-client/src/service.rs
index b48b845..3bdf6ac 100644
--- a/crates/ferese-theme-client/src/service.rs
+++ b/crates/ferese-theme-client/src/service.rs
@@ -9,6 +9,7 @@ pub fn current() -> Snapshot {
 }
 
 /// Standalone appearance; it does not represent compositor acceptance.
+#[must_use]
 pub fn fallback() -> Snapshot {
     let theme = ferese_config::theme::default_theme();
     Snapshot {
diff --git a/crates/ferese-theme-model/src/color.rs b/crates/ferese-theme-model/src/color.rs
index c710c31..1a55a3b 100644
--- a/crates/ferese-theme-model/src/color.rs
+++ b/crates/ferese-theme-model/src/color.rs
@@ -17,6 +17,7 @@ pub fn rgba(s: &str) -> Result<[f64; 4], String> {
     Ok(out)
 }
 
+#[must_use]
 pub fn hex(c: [f64; 4]) -> String {
     format!(
         "#{:02X}{:02X}{:02X}{:02X}",
@@ -27,6 +28,7 @@ pub fn hex(c: [f64; 4]) -> String {
     )
 }
 
+#[must_use]
 pub fn luminance(c: [f64; 4]) -> f64 {
     let linear = |v: f64| {
         if v <= 0.04045 {
@@ -38,11 +40,13 @@ pub fn luminance(c: [f64; 4]) -> f64 {
     0.2126 * linear(c[0]) + 0.7152 * linear(c[1]) + 0.0722 * linear(c[2])
 }
 
+#[must_use]
 pub fn contrast(a: [f64; 4], b: [f64; 4]) -> f64 {
     let (a, b) = (luminance(a), luminance(b));
     (a.max(b) + 0.05) / (a.min(b) + 0.05)
 }
 
+#[must_use]
 pub fn composite(fg: [f64; 4], bg: [f64; 4]) -> [f64; 4] {
     let mut c = [0.; 4];
     for i in 0..3 {
@@ -52,10 +56,12 @@ pub fn composite(fg: [f64; 4], bg: [f64; 4]) -> [f64; 4] {
     c
 }
 
+#[must_use]
 pub fn blend(a: [f64; 4], b: [f64; 4], p: f64) -> [f64; 4] {
     std::array::from_fn(|i| a[i] + (b[i] - a[i]) * p)
 }
 
+#[must_use]
 pub fn readable(preferred: [f64; 4], background: [f64; 4], minimum: f64) -> [f64; 4] {
     let mut preferred = preferred;
     preferred[3] = 1.;
@@ -78,6 +84,7 @@ pub fn readable(preferred: [f64; 4], background: [f64; 4], minimum: f64) -> [f64
     target
 }
 
+#[must_use]
 pub fn readable_across(
     mut preferred: [f64; 4],
     backgrounds: &[[f64; 4]],
@@ -109,6 +116,7 @@ pub fn readable_across(
     target
 }
 
+#[must_use]
 pub fn material_bounds(mut surface: [f64; 4], opacity: f64) -> [[f64; 4]; 2] {
     surface[3] = opacity;
     [
diff --git a/crates/ferese-theme-model/src/families.rs b/crates/ferese-theme-model/src/families.rs
index 5375abb..2bec215 100644
--- a/crates/ferese-theme-model/src/families.rs
+++ b/crates/ferese-theme-model/src/families.rs
@@ -34,6 +34,7 @@ pub struct Family {
 }
 
 impl Family {
+    #[must_use]
     pub fn palette(&self, appearance: Appearance) -> Option<&Palette> {
         match appearance {
             Appearance::Light => self.light.as_ref(),
@@ -41,6 +42,7 @@ impl Family {
         }
     }
 
+    #[must_use]
     pub fn availability(&self) -> &'static str {
         match (self.light.is_some(), self.dark.is_some()) {
             (true, true) => "light and dark",
diff --git a/crates/ferese-theme-model/src/resolved_theme.rs b/crates/ferese-theme-model/src/resolved_theme.rs
index 3cfa504..b61d9fc 100644
--- a/crates/ferese-theme-model/src/resolved_theme.rs
+++ b/crates/ferese-theme-model/src/resolved_theme.rs
@@ -121,6 +121,7 @@ pub struct Paint {
 }
 
 impl Paint {
+    #[must_use]
     pub fn effective_gradient(&self) -> Option<&Gradient> {
         if self.style == PaintStyle::Solid {
             None
@@ -153,6 +154,7 @@ pub struct ResolvedTheme {
 }
 
 /// Accessibility takes precedence over a panel's authored opacity.
+#[must_use]
 pub fn effective_panel_opacity(
     inherited: f32,
     custom: Option<f32>,
@@ -166,6 +168,7 @@ pub fn effective_panel_opacity(
 }
 
 impl ResolvedTheme {
+    #[must_use]
     pub fn panel_opacity(&self, custom: Option<f32>) -> f32 {
         let inherited = if self.tokens.material.style == "translucent" {
             self.tokens.material.opacity as f32
diff --git a/crates/ferese-theme/src/button.rs b/crates/ferese-theme/src/button.rs
index 863990e..ba5faf7 100644
--- a/crates/ferese-theme/src/button.rs
+++ b/crates/ferese-theme/src/button.rs
@@ -45,6 +45,7 @@ pub(crate) fn accent_button_style(
 }
 
 /// Filled accent buttons and selected rows share this per-state contrast policy.
+#[must_use]
 pub fn accent_button() -> theme::Button {
     theme::Button::Custom {
         active: Box::new(|focused, theme| accent_button_style(theme, State::Active, focused)),
diff --git a/crates/ferese-theme/src/calendar.rs b/crates/ferese-theme/src/calendar.rs
index c8ec9ca..6039c56 100644
--- a/crates/ferese-theme/src/calendar.rs
+++ b/crates/ferese-theme/src/calendar.rs
@@ -5,6 +5,7 @@ use cosmic::widget::{column, container, row};
 use cosmic::{Element, theme};
 use jiff::Zoned;
 
+#[must_use]
 pub fn format_bar_time(now: &Zoned) -> String {
     let months = [
         "jan", "feb", "mar", "apr", "may", "jun", "jul", "aug", "sept", "oct", "nov", "dec",
@@ -20,6 +21,7 @@ pub fn format_bar_time(now: &Zoned) -> String {
         if hour < 12 { "am" } else { "pm" }
     )
 }
+#[must_use]
 pub fn month(today: jiff::civil::Date, offset: i32) -> (jiff::civil::Date, usize, usize) {
     let month_index = i32::from(today.year()) * 12 + i32::from(today.month()) - 1 + offset;
     let year = month_index.div_euclid(12) as i16;
@@ -30,6 +32,7 @@ pub fn month(today: jiff::civil::Date, offset: i32) -> (jiff::civil::Date, usize
     (first, start, days)
 }
 
+#[must_use]
 pub fn grid<'a, M: Clone + 'a>(
     today: jiff::civil::Date,
     offset: i32,
@@ -41,6 +44,7 @@ pub fn grid<'a, M: Clone + 'a>(
     grid_with_density(today, offset, palette, font, opacity, navigation, false)
 }
 
+#[must_use]
 pub fn compact_grid<'a, M: Clone + 'a>(
     today: jiff::civil::Date,
     offset: i32,
diff --git a/crates/ferese-theme/src/contrast.rs b/crates/ferese-theme/src/contrast.rs
index 60f2622..687d80c 100644
--- a/crates/ferese-theme/src/contrast.rs
+++ b/crates/ferese-theme/src/contrast.rs
@@ -1,5 +1,6 @@
 use cosmic::iced::Color;
 
+#[must_use]
 pub fn luminance(color: Color) -> f32 {
     let linear = |v: f32| {
         if v <= 0.04045 {
@@ -11,6 +12,7 @@ pub fn luminance(color: Color) -> f32 {
     0.2126 * linear(color.r) + 0.7152 * linear(color.g) + 0.0722 * linear(color.b)
 }
 
+#[must_use]
 pub fn contrast(a: Color, b: Color) -> f32 {
     let (a, b) = (luminance(a), luminance(b));
     (a.max(b) + 0.05) / (a.min(b) + 0.05)
@@ -19,6 +21,7 @@ pub fn contrast(a: Color, b: Color) -> f32 {
 /// Resolve a control fill against its surface before selecting its foreground.
 /// The returned fill is opaque, so wallpaper and translucent panels cannot change
 /// the contrast of a small, filled control.
+#[must_use]
 pub fn composite(fill: Color, surface: Color) -> Color {
     let a = fill.a.clamp(0., 1.);
     Color::from_rgb(
@@ -30,6 +33,7 @@ pub fn composite(fill: Color, surface: Color) -> Color {
 
 /// Preserve the user's preferred color when it passes normal-text contrast.
 /// Otherwise black or white always provides at least 4.5:1 on an opaque sRGB fill.
+#[must_use]
 pub fn foreground(background: Color, preferred: Color) -> Color {
     let preferred = composite(preferred, background);
     if contrast(background, preferred) >= 4.5 {
@@ -44,6 +48,7 @@ pub fn foreground(background: Color, preferred: Color) -> Color {
 
 /// Prefer the theme's foreground for filled controls by adjusting the accent's
 /// brightness until the text has enough contrast.
+#[must_use]
 pub fn accent_pair(background: Color, preferred: Color) -> (Color, Color) {
     let on = composite(preferred, background);
     let shade = if luminance(on) > luminance(background) {
@@ -67,6 +72,7 @@ pub fn accent_pair(background: Color, preferred: Color) -> (Color, Color) {
 }
 
 /// Resolve configured accent transparency before passing an opaque color to a toolkit.
+#[must_use]
 pub fn accent_color(accent: Color, surface: Color) -> cosmic::cosmic_theme::palette::Srgb {
     rgba(composite(accent, surface)).color
 }
diff --git a/crates/ferese-theme/src/controls.rs b/crates/ferese-theme/src/controls.rs
index 33bfc7c..bc1100d 100644
--- a/crates/ferese-theme/src/controls.rs
+++ b/crates/ferese-theme/src/controls.rs
@@ -5,23 +5,28 @@ use cosmic::{theme, widget};
 
 use crate::{Palette, mix};
 
+#[must_use]
 pub fn surface(background: Color, radius: f32) -> theme::Container<'static> {
     theme::Container::custom(move |_| surface_appearance(background, radius))
 }
 
+#[must_use]
 pub fn button_style(p: Palette, selected: bool) -> theme::Button {
     button_style_with_focus(p, selected, true)
 }
 
+#[must_use]
 pub fn button_style_with_focus(p: Palette, selected: bool, focus_visible: bool) -> theme::Button {
     styled_button(p, selected, false, 1.0, focus_visible)
 }
 
 /// Selection cards share native button states while revealing the modal material.
+#[must_use]
 pub fn material_button_style(p: Palette, selected: bool, material_opacity: f32) -> theme::Button {
     material_button_style_with_focus(p, selected, material_opacity, true)
 }
 
+#[must_use]
 pub fn material_button_style_with_focus(
     p: Palette,
     selected: bool,
@@ -101,10 +106,12 @@ pub(crate) fn switch_colors(palette: Palette, enabled: bool, hovered: bool) -> (
     (track, thumb)
 }
 
+#[must_use]
 pub fn navigation_style(p: Palette, selected: bool) -> theme::Button {
     styled_button(p, selected, true, 1.0, true)
 }
 
+#[must_use]
 pub fn settings_input(p: Palette) -> theme::TextInput {
     let appearance = move |focused: bool, hovered: bool| cosmic::widget::text_input::Appearance {
         shape: Some(BorderShape::Continuous),
@@ -229,6 +236,7 @@ fn styled_button(
 
 /// Authentication actions use normal text while enabled and muted text while disabled.
 /// Keep the disabled fill neutral so contrast correction cannot make it look active.
+#[must_use]
 pub fn authentication_button(palette: Palette) -> theme::Button {
     let paint = move |enabled: bool, interaction: f32, focused: bool| {
         let (fill, foreground) = if enabled {
@@ -260,6 +268,7 @@ pub fn authentication_button(palette: Palette) -> theme::Button {
     }
 }
 
+#[must_use]
 pub fn authentication_input(palette: Palette) -> theme::TextInput {
     let text = palette.text;
     let muted = palette.muted;
@@ -293,6 +302,7 @@ pub fn authentication_input(palette: Palette) -> theme::TextInput {
     }
 }
 
+#[must_use]
 pub fn lock_input(
     radius: f32,
     accent: cosmic::iced::Color,
@@ -361,6 +371,7 @@ pub fn shell_button(
     }
 }
 
+#[must_use]
 pub fn surface_appearance(background: Color, radius: f32) -> container::Style {
     container::Style {
         background: Some(Background::Color(background)),
@@ -373,6 +384,7 @@ pub fn surface_appearance(background: Color, radius: f32) -> container::Style {
     }
 }
 
+#[must_use]
 pub fn notification_button(
     foreground: Color,
     hover: Color,
@@ -396,6 +408,7 @@ pub fn notification_button(
     }
 }
 
+#[must_use]
 pub fn filled_button(fill: Color, foreground: Color, radius: f32, opacity: f32) -> theme::Button {
     let paint = move |outline| button::Style {
         shape: Some(BorderShape::Continuous),
diff --git a/crates/ferese-theme/src/gallery.rs b/crates/ferese-theme/src/gallery.rs
index 7c1a972..4d4b3b1 100644
--- a/crates/ferese-theme/src/gallery.rs
+++ b/crates/ferese-theme/src/gallery.rs
@@ -174,6 +174,7 @@ fn desktop(p: &Palette) -> String {
     )
 }
 
+#[must_use]
 pub fn svg(
     family: &Family,
     variant: Option<Appearance>,
@@ -274,6 +275,7 @@ fn svg_with_radius(
     result
 }
 
+#[must_use]
 pub fn neighbor(index: usize, count: usize, key: &keyboard::key::Named) -> Option<usize> {
     use keyboard::key::Named::*;
     if count == 0 {
diff --git a/crates/ferese-theme/src/geometry.rs b/crates/ferese-theme/src/geometry.rs
index 05096b2..ddd3b54 100644
--- a/crates/ferese-theme/src/geometry.rs
+++ b/crates/ferese-theme/src/geometry.rs
@@ -1,4 +1,5 @@
 /// Radius of a circular inset. Squircle insets retain an `Outline` and its distance offset.
+#[must_use]
 pub fn inner_radius(outer: f32, padding: f32) -> f32 {
     (outer - padding).max(0.0)
 }
diff --git a/crates/ferese-theme/src/icons.rs b/crates/ferese-theme/src/icons.rs
index fd43384..c2f741a 100644
--- a/crates/ferese-theme/src/icons.rs
+++ b/crates/ferese-theme/src/icons.rs
@@ -186,6 +186,7 @@ pub fn accented(source: &'static [u8], size: u16, foreground: Color, accent: Col
         }))
 }
 
+#[must_use]
 pub fn tint_svg(source: &[u8], foreground: Color, accent: Color) -> Vec<u8> {
     let rgba = |foreground: Color| {
         format!(
diff --git a/crates/ferese-theme/src/menus.rs b/crates/ferese-theme/src/menus.rs
index ab5f0e5..acff0ef 100644
--- a/crates/ferese-theme/src/menus.rs
+++ b/crates/ferese-theme/src/menus.rs
@@ -37,6 +37,7 @@ pub fn heading<'a, M: 'a>(
         .align_y(Alignment::Center)
 }
 
+#[must_use]
 pub fn badge<'a, M: 'a>(
     content: Element<'a, M>,
     accent: Color,
@@ -55,6 +56,7 @@ pub fn badge<'a, M: 'a>(
         .into()
 }
 
+#[must_use]
 pub fn section<'a, M: 'a>(
     content: Element<'a, M>,
     foreground: Color,
@@ -84,6 +86,7 @@ pub fn section_label<'a>(
         .class(cosmic::theme::Text::Color(muted))
 }
 
+#[must_use]
 pub fn separator<'a, M: 'a>(foreground: Color, opacity: f32) -> Element<'a, M> {
     container(cosmic::widget::Space::new().width(Length::Fill).height(1))
         .class(crate::controls::surface(
@@ -93,6 +96,7 @@ pub fn separator<'a, M: 'a>(foreground: Color, opacity: f32) -> Element<'a, M> {
         .into()
 }
 
+#[must_use]
 pub fn switch<'a, M: 'a>(enabled: bool, palette: crate::Palette, opacity: f32) -> Element<'a, M> {
     let (track, thumb) = crate::controls::switch_colors(palette, enabled, false);
     let track_radius = 10.;
@@ -123,6 +127,7 @@ pub fn switch<'a, M: 'a>(enabled: bool, palette: crate::Palette, opacity: f32) -
         .into()
 }
 
+#[must_use]
 pub fn slider(foreground: Color, opacity: f32) -> cosmic::theme::iced::Slider {
     let style = std::rc::Rc::new(move |_: &cosmic::Theme| {
         use cosmic::iced::widget::slider::{Breakpoint, Handle, HandleShape, Rail, Style};
diff --git a/crates/ferese-theme/src/palette.rs b/crates/ferese-theme/src/palette.rs
index 48fc1e8..73f257b 100644
--- a/crates/ferese-theme/src/palette.rs
+++ b/crates/ferese-theme/src/palette.rs
@@ -19,6 +19,7 @@ pub struct Palette {
 }
 
 impl Palette {
+    #[must_use]
     pub fn from_resolved(theme: &ferese_theme_model::ResolvedTheme) -> Self {
         let color = |value: &str| parse_color(value).expect("validated resolved theme color");
         Self {
@@ -50,6 +51,7 @@ impl Palette {
         }
     }
 
+    #[must_use]
     pub fn flat(mut self) -> Self {
         self.background = self.sidebar;
         self.card = self.sidebar;
@@ -138,6 +140,7 @@ impl Palette {
         cosmic::Theme::custom(std::sync::Arc::new(native)).corner_shape(BorderShape::Continuous)
     }
 
+    #[must_use]
     pub fn application_style(self, background: Color) -> cosmic::iced::theme::Style {
         cosmic::iced::theme::Style {
             background_color: background,
@@ -147,6 +150,7 @@ impl Palette {
     }
 }
 
+#[must_use]
 pub fn parse_color(value: &str) -> Option<Color> {
     let hex = value.strip_prefix('#')?;
     let packed = u32::from_str_radix(hex, 16).ok()?;
@@ -163,6 +167,7 @@ pub fn parse_color(value: &str) -> Option<Color> {
     ))
 }
 
+#[must_use]
 pub fn mix(a: Color, b: Color, t: f32) -> Color {
     Color::from_rgb(
         a.r + (b.r - a.r) * t,
@@ -171,6 +176,7 @@ pub fn mix(a: Color, b: Color, t: f32) -> Color {
     )
 }
 
+#[must_use]
 pub fn surface_shade(base: Color) -> Color {
     if crate::luminance(base) > 0.5 {
         Color::BLACK
@@ -179,6 +185,7 @@ pub fn surface_shade(base: Color) -> Color {
     }
 }
 
+#[must_use]
 pub fn material_opacity(theme: &ferese_theme_model::ResolvedTheme) -> f32 {
     if theme.tokens.material.style == "translucent" {
         theme.tokens.material.opacity as f32
diff --git a/crates/ferese-theme/src/panel_surface.rs b/crates/ferese-theme/src/panel_surface.rs
index 556816c..941be75 100644
--- a/crates/ferese-theme/src/panel_surface.rs
+++ b/crates/ferese-theme/src/panel_surface.rs
@@ -107,7 +107,7 @@ impl<M> Surface<'_, M> {
             &mut collector,
         );
         let size = layout.bounds().size();
-        let scene = PixelGrid::new(self.options.scale)
+        let scene = PixelGrid::try_new(self.options.scale)
             .and_then(|grid| {
                 ferese_panel::scene::derive(
                     self.options.parameters,
diff --git a/crates/ferese-theme/src/workspaces.rs b/crates/ferese-theme/src/workspaces.rs
index 658be83..b756eb8 100644
--- a/crates/ferese-theme/src/workspaces.rs
+++ b/crates/ferese-theme/src/workspaces.rs
@@ -16,6 +16,7 @@ pub struct Workspace<'a> {
     pub visible_elsewhere: bool,
 }
 
+#[must_use]
 pub fn width(style: WorkspaceStyle) -> f32 {
     match style {
         WorkspaceStyle::Numbers | WorkspaceStyle::Dots => 24.,
@@ -25,6 +26,7 @@ pub fn width(style: WorkspaceStyle) -> f32 {
     }
 }
 
+#[must_use]
 pub fn tooltip_label(workspace: &Workspace<'_>) -> String {
     let name = if workspace.name.is_empty() || workspace.name == workspace.index.to_string() {
         String::new()
@@ -44,6 +46,7 @@ pub fn tooltip_label(workspace: &Workspace<'_>) -> String {
     )
 }
 
+#[must_use]
 pub fn indicator<'a, M: 'a>(
     style: WorkspaceStyle,
     workspace: Workspace<'a>,
@@ -193,6 +196,7 @@ pub fn indicator<'a, M: 'a>(
         .into()
 }
 
+#[must_use]
 pub fn sample<'a, M: 'a>(
     style: WorkspaceStyle,
     palette: Palette,
diff --git a/feresectl/src/activities.rs b/feresectl/src/activities.rs
index 3d92c10..60ec278 100644
--- a/feresectl/src/activities.rs
+++ b/feresectl/src/activities.rs
@@ -87,15 +87,14 @@ pub enum ResultKind {
     Fail,
     Cancelled,
 }
-fn handle(value: &Option<String>) -> Result<Option<Id>, Box<dyn Error>> {
+fn handle(value: Option<&str>) -> Result<Option<Id>, Box<dyn Error>> {
     value
-        .as_ref()
         .map(|value| serde_json::from_str(value).map_err(Into::into))
         .transpose()
 }
 fn value(
     progress: Option<f32>,
-    message: &Option<String>,
+    message: Option<&str>,
     remaining_ms: Option<u64>,
 ) -> Result<Option<Value>, Box<dyn Error>> {
     if usize::from(progress.is_some())
@@ -107,7 +106,7 @@ fn value(
     }
     Ok(progress
         .map(Value::Progress)
-        .or_else(|| message.clone().map(Value::Text))
+        .or_else(|| message.map(|message| Value::Text(message.to_owned())))
         .or_else(|| {
             remaining_ms.map(|remaining_ms| Value::Countdown {
                 remaining_ms,
@@ -156,7 +155,8 @@ pub fn command(action: &Action, socket: &Path, json_output: bool) -> Result<(),
             priority,
             lease_ms,
         } => {
-            let value = value(*progress, message, *remaining_ms)?.unwrap_or(Value::Indeterminate);
+            let value = value(*progress, message.as_deref(), *remaining_ms)?
+                .unwrap_or(Value::Indeterminate);
             let data = Data {
                 source: if let Some(source) = source {
                     serde_json::from_value(json!(source))?
@@ -196,8 +196,8 @@ pub fn command(action: &Action, socket: &Path, json_output: bool) -> Result<(),
             handle: token,
         } => Publish::Update {
             local: local.clone(),
-            handle: handle(token)?,
-            value: value(*progress, message, *remaining_ms)?,
+            handle: handle(token.as_deref())?,
+            value: value(*progress, message.as_deref(), *remaining_ms)?,
             lease_ms: *lease_ms,
         },
         Action::End {
@@ -207,7 +207,7 @@ pub fn command(action: &Action, socket: &Path, json_output: bool) -> Result<(),
             handle: token,
         } => Publish::End {
             local: local.clone(),
-            handle: handle(token)?,
+            handle: handle(token.as_deref())?,
             result: match result {
                 ResultKind::Ok => State::Done,
                 ResultKind::Fail => State::Failed,
@@ -220,7 +220,7 @@ pub fn command(action: &Action, socket: &Path, json_output: bool) -> Result<(),
             handle: token,
         } => Publish::Cancel {
             local: local.clone(),
-            handle: handle(token)?,
+            handle: handle(token.as_deref())?,
         },
         Action::Hook {
             local,
diff --git a/shell/ferese-shell/src/panel_hub.rs b/shell/ferese-shell/src/panel_hub.rs
index 803584c..9fbf166 100644
--- a/shell/ferese-shell/src/panel_hub.rs
+++ b/shell/ferese-shell/src/panel_hub.rs
@@ -93,7 +93,7 @@ pub(super) struct Runtime {
 
 impl Runtime {
     pub(super) fn new(panel: &Panel) -> Self {
-        let mut hub = Hub::new(panel.morph, panel.resolved_geometry().height.into())
+        let mut hub = Hub::try_new(panel.morph, panel.resolved_geometry().height.into())
             .expect("validated panel hub");
         hub.pin_radii(panel.corner_radius.map(|r| r.0.map(f64::from)))
             .expect("validated panel radii");
@@ -3539,7 +3539,7 @@ mod tests {
                             bounds.height,
                         ),
                         &[],
-                        ferese_panel::shape::PixelGrid::new(1.5).unwrap(),
+                        ferese_panel::shape::PixelGrid::try_new(1.5).unwrap(),
                     )
                     .unwrap();
                     assert_eq!(scene.paint.len(), 3);