diff --git a/src/app/AppSidebar.tsx b/src/app/AppSidebar.tsx
index 186b1d57..9fe9f28e 100644
--- a/src/app/AppSidebar.tsx
+++ b/src/app/AppSidebar.tsx
@@ -76,7 +76,7 @@ function SidebarDeviceRow({
   const device = snapshot.devices.find((entry) => entry.index === index);
   if (!device) return null;
   const live = device.selected && (snapshot.deviceStatus !== null || snapshot.keyboard !== null);
-  const status = live ? snapshot.deviceStatus : null;
+  const mouseStatus = live ? snapshot.deviceStatus : null;
   const image = deviceImage({ vendorId: device.vendorId, productId: device.productId } as HIDDevice, device.name);
   return (
     <li>
@@ -102,10 +102,10 @@ function SidebarDeviceRow({
         <span className="om-side-device-text">
           <span className="om-side-device-name">{device.name}</span>
           <span className="om-side-device-sub">
-            {status?.batteryPercent != null ? (
+            {mouseStatus?.batteryPercent != null ? (
               <>
-                <BatteryIcon percent={status.batteryPercent} state={status.batteryState} />
-                <span>{status.batteryPercent}%</span>
+                <BatteryIcon percent={mouseStatus.batteryPercent} state={mouseStatus.batteryState} />
+                <span>{mouseStatus.batteryPercent}%</span>
               </>
             ) : (
               <span>{live ? t(locale, "side.connected") : t(locale, "home.notConnected")}</span>
diff --git a/src/device/controller.ts b/src/device/controller.ts
index 35cb8aaf..9f6c4c04 100644
--- a/src/device/controller.ts
+++ b/src/device/controller.ts
@@ -280,8 +280,13 @@ let keyboardWorkspace = emptyKeyboardWorkspace();
 let keyboardBusy = false;
 let keyboardStatusText: string | null = null;
 let x11PollingRateHz = (() => {
-  const saved = Number(window.localStorage.getItem(X11_POLLING_STORAGE_KEY));
-  return X11_POLLING_RATES_HZ.includes(saved) ? saved : 1000;
+  try {
+    const saved = Number(window.localStorage.getItem(X11_POLLING_STORAGE_KEY));
+    return X11_POLLING_RATES_HZ.includes(saved) ? saved : 1000;
+  } catch {
+    // Storage can be unavailable (private mode, blocked cookies).
+    return 1000;
+  }
 })();
 
 /** True for the specific Attack Shark X11 units whose settings channel is native-only. */
@@ -5441,7 +5446,11 @@ export function applyPollingRate(rate: number): void {
       if (nativeX11) {
         await applyBridgeNativeSettings({ brand: "Attack Shark", pollingRateHz: rate });
         x11PollingRateHz = rate;
-        window.localStorage.setItem(X11_POLLING_STORAGE_KEY, String(rate));
+        try {
+          window.localStorage.setItem(X11_POLLING_STORAGE_KEY, String(rate));
+        } catch {
+          // The rate is applied; persistence is best effort.
+        }
       } else {
         await requireClientMethod("setPollingRate", "the polling rate").setPollingRate(rate);
       }
diff --git a/src/features/buttons/ButtonMap.tsx b/src/features/buttons/ButtonMap.tsx
index 13b5f2d1..10ff63d8 100644
--- a/src/features/buttons/ButtonMap.tsx
+++ b/src/features/buttons/ButtonMap.tsx
@@ -92,8 +92,19 @@ export function ButtonMap({ snapshot: live }: { snapshot: ControlSnapshot }): Re
         setRecording(false);
         return;
       }
+      const isModifierKey = event.code === "ShiftLeft" || event.code === "ShiftRight" || event.code === "ControlLeft" || event.code === "ControlRight" || event.code === "AltLeft" || event.code === "AltRight" || event.code === "MetaLeft" || event.code === "MetaRight" || event.code === "OSLeft" || event.code === "OSRight";
+      if (isModifierKey) {
+        return;
+      }
       const binding = bindingFromKeyEvent(event);
-      if (!binding || binding.kind !== "keyboard") return;
+      if (!binding) {
+        setRecording(false);
+        return;
+      }
+      if (binding.kind !== "keyboard") {
+        setRecording(false);
+        return;
+      }
       void control.applyLogitechButtonAssignment(layer, selected, binding);
       setPending((previous) => ({ ...previous, [`${layer}-${selected}`]: shortcutText(binding.key, binding.modifiers) }));
       setRecording(false);
@@ -132,8 +143,12 @@ export function ButtonMap({ snapshot: live }: { snapshot: ControlSnapshot }): Re
   const defaultFor = (button: number): LogitechButtonAction => (layer === "primary" ? DEFAULT_ACTION[button] : "Disabled") as LogitechButtonAction;
   const reset = async (buttons: number[]): Promise<void> => {
     for (const button of buttons) {
-      await control.applyLogitechButtonAssignment(layer, button, defaultFor(button));
-      setPending((previous) => ({ ...previous, [`${layer}-${button}`]: defaultFor(button) }));
+      try {
+        await control.applyLogitechButtonAssignment(layer, button, defaultFor(button));
+        setPending((previous) => ({ ...previous, [`${layer}-${button}`]: defaultFor(button) }));
+      } catch {
+        // Keep going; failure is reported through the existing pending/flash flow.
+      }
     }
   };
   const unlocked = layout.spots.filter((spot) => !isLocked(spot)).map((spot) => spot.button);
diff --git a/src/features/capture/CaptureDialog.tsx b/src/features/capture/CaptureDialog.tsx
index d3766a5a..a0b241e0 100644
--- a/src/features/capture/CaptureDialog.tsx
+++ b/src/features/capture/CaptureDialog.tsx
@@ -207,7 +207,7 @@ export function CaptureDialog({ open, onClose, locale = "en" }: { open: boolean;
                 diffs,
                 sectors,
               });
-              void navigator.clipboard.writeText(markdown).then(
+              void (navigator.clipboard?.writeText(markdown) ?? Promise.reject(new Error("Clipboard unavailable."))).then(
                 () => setMessage("Capture copied — paste it into a GitHub issue."),
                 () => setMessage("Could not copy to the clipboard."),
               );
diff --git a/src/features/devices/OverviewPage.tsx b/src/features/devices/OverviewPage.tsx
index a2ffe46b..22d371fc 100644
--- a/src/features/devices/OverviewPage.tsx
+++ b/src/features/devices/OverviewPage.tsx
@@ -141,7 +141,7 @@ function M2NexProfileOverview({ snapshot }: { snapshot: ControlSnapshot }): Reac
   const isNoirProfile = isNoirKsnakeStatus(status);
   const profileImportRef = useRef<HTMLInputElement>(null);
   if (!status || !isNoirProfile || snapshot.m2nexProfiles === null) return null;
-  const profile = snapshot.m2nexProfiles[snapshot.activeM2NexProfile];
+  const profile = snapshot.m2nexProfiles[snapshot.activeM2NexProfile] ?? snapshot.m2nexProfiles[0];
   if (!profile) return null;
   const applyDisabled = snapshot.settingInProgress || snapshot.pending.count > 0;
   return (
@@ -206,7 +206,12 @@ function M2NexProfileOverview({ snapshot }: { snapshot: ControlSnapshot }): Reac
           const file = event.currentTarget.files?.[0];
           event.currentTarget.value = "";
           if (!file) return;
-          void file.text().then((text) => control.importM2NexProfiles(text));
+          void file
+            .text()
+            .then((text) => control.importM2NexProfiles(text))
+            .catch((error) => {
+              control.pushToast("error", "Import failed", error instanceof Error ? error.message : undefined);
+            });
         }}
       />
     </section>
diff --git a/src/features/devices/cards/DpiCard.tsx b/src/features/devices/cards/DpiCard.tsx
index efd26b1e..d8e1a1b1 100644
--- a/src/features/devices/cards/DpiCard.tsx
+++ b/src/features/devices/cards/DpiCard.tsx
@@ -239,14 +239,14 @@ function DpiStageEditor({
     }
   };
 
-  const markEdited = (next: StageRow[], delay = 450): void => {
+  const markEdited = (delay = 450, nextRows?: StageRow[]): void => {
     touchedRef.current = Date.now();
+    const snapshotRows = nextRows ?? rowsRef.current;
     if (timerRef.current) clearTimeout(timerRef.current);
     timerRef.current = setTimeout(() => {
       timerRef.current = null;
-      commit(rowsRef.current);
+      commit(snapshotRows);
     }, delay);
-    void next;
   };
 
   const flushEdit = (): void => {
@@ -284,7 +284,7 @@ function DpiStageEditor({
     if (fixedStageCount) return;
     setRows(next);
     rowsRef.current = next;
-    markEdited(next);
+    markEdited();
   };
 
   const TYPING_DELAY = 1200;
@@ -296,7 +296,7 @@ function DpiStageEditor({
       : row));
     setRows(next);
     rowsRef.current = next;
-    markEdited(next, delay);
+    markEdited(delay);
   };
 
   const inputEdit = (event: Event, oldRaw: string): { raw: string; delay?: number } => {
@@ -321,14 +321,14 @@ function DpiStageEditor({
     });
     setRows(next);
     rowsRef.current = next;
-    markEdited(next);
+    markEdited();
   };
 
   const setValueY = (index: number, raw: string, delay?: number): void => {
     const next = rows.map((row, i) => (i === index ? { ...row, valueY: raw.replace(/[^\d]/g, "") } : row));
     setRows(next);
     rowsRef.current = next;
-    markEdited(next, delay);
+    markEdited(delay);
   };
 
   const setSlider = (index: number, numeric: number): void => setValue(index, String(numeric));
diff --git a/src/features/devices/cards/PerformanceCards.tsx b/src/features/devices/cards/PerformanceCards.tsx
index 2d65ebc2..eccbaa47 100644
--- a/src/features/devices/cards/PerformanceCards.tsx
+++ b/src/features/devices/cards/PerformanceCards.tsx
@@ -496,7 +496,7 @@ export function DynamicSensitivityCard({ snapshot }: { snapshot: ControlSnapshot
 
   const customPoints = draft ?? curves?.custom ?? null;
   const updateDraftPoint = (index: number, field: "speed" | "gain", value: number): void => {
-    const base = (curves?.custom ?? []).map((point) => ({ ...point }));
+    const base = (draft ?? curves?.custom ?? []).map((point) => ({ ...point }));
     while (base.length < 5) base.push({ speed: 0, gain: 1 });
     base[index] = { ...base[index]!, [field]: value };
     setDraft(base);
diff --git a/src/features/devices/cards/availability.ts b/src/features/devices/cards/availability.ts
index 0bbe82c7..6eb18d0b 100644
--- a/src/features/devices/cards/availability.ts
+++ b/src/features/devices/cards/availability.ts
@@ -136,7 +136,6 @@ function computeCardAvailability(snapshot: ControlSnapshot): CardAvailability {
     || status.angleTuning != null
     || status.longRangeMode != null
     || status.sensorMode != null || status.performanceDuration != null
-    || status.longRangeMode != null
   );
 
   const eggs = host && traits.eggControls;
diff --git a/src/features/hardware-test/HardwareTestPage.tsx b/src/features/hardware-test/HardwareTestPage.tsx
index e249a2a0..46b4a56d 100644
--- a/src/features/hardware-test/HardwareTestPage.tsx
+++ b/src/features/hardware-test/HardwareTestPage.tsx
@@ -257,7 +257,9 @@ export function HardwareTestPage({ snapshot }: { snapshot: ControlSnapshot }): R
             return { setting: leg.setting, current: leg.current, target: leg.target, status: "fail", detail: `wrote ${leg.target} but read back something else — the write did not stick.` };
           }
           try {
-            leg.stageRestore();
+            if (!leg.stageRestore()) {
+              return { setting: leg.setting, current: leg.current, target: leg.target, status: "fail", detail: `restore to ${leg.current} failed after reading back ${leg.target} — device settings may have changed.` };
+            }
             await control.flashPendingChanges();
             if (leg.read() !== leg.currentRaw) {
               return { setting: leg.setting, current: leg.current, target: leg.target, status: "fail", detail: `restore to ${leg.current} failed after reading back ${leg.target} — device settings may have changed.` };
@@ -298,7 +300,13 @@ export function HardwareTestPage({ snapshot }: { snapshot: ControlSnapshot }): R
                   currentRaw: dpiCurrent,
                   targetRaw: dpiTarget,
                   stageTarget: () => control.applyDpiValue(dpiTarget),
-                  stageRestore: () => control.applyDpiValue(dpiCurrent),
+                  stageRestore: () => {
+                    try {
+                      return control.applyDpiValue(dpiCurrent);
+                    } catch {
+                      return false;
+                    }
+                  },
                   read: () => control.getSnapshot().status?.dpi ?? null,
                 }));
               }
@@ -320,8 +328,22 @@ export function HardwareTestPage({ snapshot }: { snapshot: ControlSnapshot }): R
                   note: "the reporting rate changes briefly",
                   currentRaw: rateCurrent,
                   targetRaw: rateTarget,
-                  stageTarget: () => { control.applyPollingRate(rateTarget); return true; },
-                  stageRestore: () => { control.applyPollingRate(rateCurrent); return true; },
+                  stageTarget: () => {
+                    try {
+                      control.applyPollingRate(rateTarget);
+                      return true;
+                    } catch {
+                      return false;
+                    }
+                  },
+                  stageRestore: () => {
+                    try {
+                      control.applyPollingRate(rateCurrent);
+                      return true;
+                    } catch {
+                      return false;
+                    }
+                  },
                   read: () => control.getSnapshot().status?.pollingRateHz ?? null,
                 }));
               }
@@ -343,8 +365,22 @@ export function HardwareTestPage({ snapshot }: { snapshot: ControlSnapshot }): R
                   note: "the sensor lift height changes briefly",
                   currentRaw: lodCurrent,
                   targetRaw: lodTarget,
-                  stageTarget: () => { control.applyLiftOffDistance(lodTarget); return true; },
-                  stageRestore: () => { control.applyLiftOffDistance(lodCurrent); return true; },
+                  stageTarget: () => {
+                    try {
+                      control.applyLiftOffDistance(lodTarget);
+                      return true;
+                    } catch {
+                      return false;
+                    }
+                  },
+                  stageRestore: () => {
+                    try {
+                      control.applyLiftOffDistance(lodCurrent);
+                      return true;
+                    } catch {
+                      return false;
+                    }
+                  },
                   read: () => control.getSnapshot().status?.liftOffDistance ?? null,
                 }));
               }
diff --git a/src/features/news/news.test.ts b/src/features/news/news.test.ts
index 2ec736c0..5d328858 100644
--- a/src/features/news/news.test.ts
+++ b/src/features/news/news.test.ts
@@ -82,6 +82,28 @@ test("a payload without a message or id produces no banner", async () => {
   );
 });
 
+test("non-web notice links are dropped instead of reaching the banner anchor", async () => {
+  for (const url of ["javascript:alert(1)", "data:text/html,<script>alert(1)</script>", "vbscript:msgbox(1)"]) {
+    await withFetch(
+      async () => Response.json({ id: "x", message: "Hello", url }),
+      async () => {
+        assert.equal((await fetchNews())?.url, undefined, url);
+      },
+    );
+  }
+});
+
+test("web and relative notice links are kept", async () => {
+  for (const url of ["https://openmouse.app/blog", "http://example.test/note", "/news/item"]) {
+    await withFetch(
+      async () => Response.json({ id: "x", message: "Hello", url }),
+      async () => {
+        assert.equal((await fetchNews())?.url, url);
+      },
+    );
+  }
+});
+
 test("an aborted request does not retry against the fallback", async () => {
   const requested: string[] = [];
   const controller = new AbortController();
diff --git a/src/features/news/news.ts b/src/features/news/news.ts
index 0ee92bd0..475c8cd4 100644
--- a/src/features/news/news.ts
+++ b/src/features/news/news.ts
@@ -23,6 +23,21 @@ const NEWS_FALLBACK_URL = "/news.json";
 
 const LEVELS: NewsLevel[] = ["info", "warning", "critical"];
 
+/** The notice text comes from a remote JSON file, so its link must not be able
+    to become a `javascript:` (or other non-web) URL in the banner anchor. */
+function safeNewsUrl(value: unknown): string | undefined {
+  if (typeof value !== "string") return undefined;
+  const raw = value.trim();
+  if (!raw) return undefined;
+  try {
+    const parsed = new URL(raw, "https://openmouse.app/");
+    if (parsed.protocol !== "https:" && parsed.protocol !== "http:") return undefined;
+    return raw;
+  } catch {
+    return undefined;
+  }
+}
+
 async function fetchNewsFrom(url: string, signal?: AbortSignal): Promise<NewsItem | null> {
   const response = await fetch(url, { signal, cache: "no-store" });
   if (!response.ok) throw new Error(`News endpoint returned HTTP ${response.status}.`);
@@ -31,8 +46,7 @@ async function fetchNewsFrom(url: string, signal?: AbortSignal): Promise<NewsIte
   const message = typeof body.message === "string" ? body.message.trim() : "";
   if (!id || !message) return null;
   const level: NewsLevel = LEVELS.includes(body.level as NewsLevel) ? (body.level as NewsLevel) : "info";
-  const link = typeof body.url === "string" && body.url.trim() ? body.url.trim() : undefined;
-  return { id, level, message, url: link };
+  return { id, level, message, url: safeNewsUrl(body.url) };
 }
 
 export async function fetchNews(signal?: AbortSignal): Promise<NewsItem | null> {
diff --git a/src/features/settings/InterfaceSettings.tsx b/src/features/settings/InterfaceSettings.tsx
index 522be54c..f4dda809 100644
--- a/src/features/settings/InterfaceSettings.tsx
+++ b/src/features/settings/InterfaceSettings.tsx
@@ -48,11 +48,11 @@ export function ProfileKeyFields({ snapshot }: { snapshot: ControlSnapshot }): R
           disabled={!key}
           onClick={() => {
             if (!key) return;
-            void navigator.clipboard.writeText(key).then(() => {
+            void navigator.clipboard?.writeText(key).then(() => {
               track("profile_key_copied");
               setCopied(true);
               setTimeout(() => setCopied(false), 1500);
-            });
+            }).catch(() => undefined);
           }}
         >
           {displayText(locale, copied ? t(locale, "set.copied") : t(locale, "set.copyKey"))}
diff --git a/src/features/settings/interface-preferences.test.ts b/src/features/settings/interface-preferences.test.ts
index 3e3b83cf..c7ae7064 100644
--- a/src/features/settings/interface-preferences.test.ts
+++ b/src/features/settings/interface-preferences.test.ts
@@ -20,6 +20,14 @@ class MemoryStorage implements Storage {
   setItem(key: string, value: string): void { this.#values.set(key, value); }
 }
 
+test("a failing storage write does not break the settings update", () => {
+  const storage = new MemoryStorage();
+  storage.setItem = () => {
+    throw new DOMException("Quota exceeded", "QuotaExceededError");
+  };
+  assert.doesNotThrow(() => saveInterfacePreferences(storage, DEFAULT_INTERFACE_PREFERENCES));
+});
+
 test("interface preferences restore only supported values", () => {
   const storage = new MemoryStorage();
   saveInterfacePreferences(storage, {
diff --git a/src/features/settings/interface-preferences.ts b/src/features/settings/interface-preferences.ts
index f0ee43d8..a3658b26 100644
--- a/src/features/settings/interface-preferences.ts
+++ b/src/features/settings/interface-preferences.ts
@@ -129,7 +129,12 @@ export function loadInterfacePreferences(storage: Storage): InterfacePreferences
 }
 
 export function saveInterfacePreferences(storage: Storage, preferences: InterfacePreferences): void {
-  storage.setItem(STORAGE_KEY, JSON.stringify(preferences));
+  try {
+    storage.setItem(STORAGE_KEY, JSON.stringify(preferences));
+  } catch {
+    // Storage can be unavailable or full (private mode, blocked cookies).
+    // Losing persistence is preferable to breaking the settings UI.
+  }
 }
 
 /** Dataset value for the theme selector. Display names carry spaces, one
diff --git a/src/features/superstrike/HitsTestDialog.tsx b/src/features/superstrike/HitsTestDialog.tsx
index e2051ba3..4fbf3fa1 100644
--- a/src/features/superstrike/HitsTestDialog.tsx
+++ b/src/features/superstrike/HitsTestDialog.tsx
@@ -99,7 +99,7 @@ export function HitsTestDialog({
       setNote("Too early. Wait for blue.");
       setPhase("idle");
     } else if (phase === "go") {
-      const reaction = event.timeStamp - goAt.current;
+      const reaction = performance.now() - goAt.current;
       setPhase("settle");
       timer.current = window.setTimeout(() => {
         const saved = savedMs(samples.current, actuationRef.current[sideRef.current]);
diff --git a/src/platform/self-xss-guard.ts b/src/platform/self-xss-guard.ts
index cb247c72..42258d0a 100644
--- a/src/platform/self-xss-guard.ts
+++ b/src/platform/self-xss-guard.ts
@@ -11,7 +11,7 @@
  * debugging, and misfire on browsers with wide chrome (e.g. Firefox forks
  * with vertical tabs or sidebars).
  *
- * Call only on production builds (see control.tsx).
+ * Call only on production builds (see main.tsx).
  */
 
 const WARNING_TITLE = "Stop!";