diff --git a/src-tauri/src/models/settings.rs b/src-tauri/src/models/settings.rs
index 74c62fe..5953d4c 100644
--- a/src-tauri/src/models/settings.rs
+++ b/src-tauri/src/models/settings.rs
@@ -57,6 +57,7 @@ pub struct AppSettings {
     pub default_thinking: bool,
     pub first_run_completed: bool,
     pub check_for_updates: bool,
+    pub high_contrast: bool,
     pub language: Option<String>,
     pub model_directory: Option<String>,
     pub backend_working_directory: Option<String>,
@@ -93,6 +94,7 @@ impl Default for AppSettings {
             default_thinking: true,
             first_run_completed: false,
             check_for_updates: true,
+            high_contrast: false,
             language: None,
             model_directory: None,
             backend_working_directory: None,
@@ -168,6 +170,7 @@ pub enum SettingKey {
     DefaultThinking,
     FirstRunCompleted,
     CheckForUpdates,
+    HighContrast,
     Language,
     ModelDirectory,
     BackendWorkingDirectory,
@@ -188,6 +191,7 @@ impl SettingKey {
             "defaultThinking" => Ok(Self::DefaultThinking),
             "firstRunCompleted" => Ok(Self::FirstRunCompleted),
             "checkForUpdates" => Ok(Self::CheckForUpdates),
+            "highContrast" => Ok(Self::HighContrast),
             "language" => Ok(Self::Language),
             "modelDirectory" => Ok(Self::ModelDirectory),
             "backendWorkingDirectory" => Ok(Self::BackendWorkingDirectory),
@@ -211,6 +215,7 @@ impl SettingKey {
             Self::DefaultThinking => "defaultThinking",
             Self::FirstRunCompleted => "firstRunCompleted",
             Self::CheckForUpdates => "checkForUpdates",
+            Self::HighContrast => "highContrast",
             Self::Language => "language",
             Self::ModelDirectory => "modelDirectory",
             Self::BackendWorkingDirectory => "backendWorkingDirectory",
@@ -289,6 +294,11 @@ impl AppSettings {
                     AppError::validation_failed(format!("invalid checkForUpdates value: {error}"))
                 })?;
             }
+            SettingKey::HighContrast => {
+                self.high_contrast = serde_json::from_value(value).map_err(|error| {
+                    AppError::validation_failed(format!("invalid highContrast value: {error}"))
+                })?;
+            }
             SettingKey::Language => {
                 self.language = serde_json::from_value(value).map_err(|error| {
                     AppError::validation_failed(format!("invalid language value: {error}"))
@@ -353,6 +363,7 @@ impl AppSettings {
                 "checkForUpdates",
                 serde_json::to_string(&self.check_for_updates),
             ),
+            ("highContrast", serde_json::to_string(&self.high_contrast)),
             ("language", serde_json::to_string(&self.language)),
             (
                 "modelDirectory",
@@ -404,6 +415,7 @@ mod tests {
             "defaultThinking",
             "firstRunCompleted",
             "checkForUpdates",
+            "highContrast",
             "language",
             "modelDirectory",
             "backendWorkingDirectory",
diff --git a/src/app/App.tsx b/src/app/App.tsx
index a4bff09..ddfc244 100644
--- a/src/app/App.tsx
+++ b/src/app/App.tsx
@@ -8,6 +8,13 @@ import * as api from "@/app/lib/api";
 import { useGenerationStore } from "@/app/lib/store";
 import { useAppMenuRuntime } from "@/app/runtime/menu-runtime";
 
+function useHighContrast() {
+  const highContrast = useGenerationStore((s) => s.highContrast);
+  useEffect(() => {
+    document.documentElement.toggleAttribute("data-high-contrast", highContrast);
+  }, [highContrast]);
+}
+
 function BootShell() {
   return (
     <div className="flex h-screen w-full items-center justify-center bg-[#121212] text-[12px] tracking-wide text-[rgba(255,255,255,0.55)]">
@@ -17,6 +24,7 @@ function BootShell() {
 }
 
 function App() {
+  useHighContrast();
   const { t } = useTranslation();
   const { addToast } = useToast();
   const hydrateFromPersistence = useGenerationStore((state) => state.hydrateFromPersistence);
diff --git a/src/app/components/generation/GenerationPanel.tsx b/src/app/components/generation/GenerationPanel.tsx
index ff6aabb..9198b37 100644
--- a/src/app/components/generation/GenerationPanel.tsx
+++ b/src/app/components/generation/GenerationPanel.tsx
@@ -59,9 +59,13 @@ type ToggleField =
   | "useCotLanguage"
   | "constrainedDecoding";
 
-function FieldError({ message }: { message?: string }) {
+function FieldError({ message, id }: { message?: string; id?: string }) {
   if (!message) return null;
-  return <p className="text-[11px] text-red-300">{message}</p>;
+  return (
+    <p id={id} className="text-[11px] text-red-300">
+      {message}
+    </p>
+  );
 }
 
 function FieldLabel({ children }: { children: React.ReactNode }) {
@@ -396,8 +400,9 @@ export function GenerationPanel() {
             value={form.prompt}
             onChange={handleTextFieldChange("prompt")}
             disabled={isBusy}
+            aria-describedby={validationErrors.prompt ? "gen-error-prompt" : undefined}
           />
-          <FieldError message={validationErrors.prompt} />
+          <FieldError id="gen-error-prompt" message={validationErrors.prompt} />
         </label>
 
         {/* Model info - compact row */}
diff --git a/src/app/components/generation/GenerationPanel/FormBody.tsx b/src/app/components/generation/GenerationPanel/FormBody.tsx
index 40903ca..a4d5810 100644
--- a/src/app/components/generation/GenerationPanel/FormBody.tsx
+++ b/src/app/components/generation/GenerationPanel/FormBody.tsx
@@ -128,8 +128,9 @@ export function FormBody({
           value={form.prompt}
           onChange={handleTextFieldChange("prompt")}
           disabled={isBusy}
+          aria-describedby={validationErrors.prompt ? "error-prompt" : undefined}
         />
-        <FieldError message={validationErrors.prompt} />
+        <FieldError id="error-prompt" message={validationErrors.prompt} />
       </label>
 
       {/* Model info - compact row */}
@@ -223,8 +224,9 @@ export function FormBody({
           value={form.lyrics}
           onChange={handleTextFieldChange("lyrics")}
           disabled={isBusy || form.instrumental}
+          aria-describedby={validationErrors.lyrics ? "error-lyrics" : undefined}
         />
-        <FieldError message={validationErrors.lyrics} />
+        <FieldError id="error-lyrics" message={validationErrors.lyrics} />
       </div>
 
       {/* Basic parameters - grouped */}
@@ -244,8 +246,9 @@ export function FormBody({
               value={form.durationSeconds}
               onChange={handleTextFieldChange("durationSeconds")}
               disabled={isBusy}
+              aria-describedby={validationErrors.durationSeconds ? "error-duration" : undefined}
             />
-            <FieldError message={validationErrors.durationSeconds} />
+            <FieldError id="error-duration" message={validationErrors.durationSeconds} />
           </label>
           <label className="space-y-1">
             <FieldLabel>{t("generation.bpm")}</FieldLabel>
@@ -271,9 +274,10 @@ export function FormBody({
                 value={form.bpm}
                 onChange={handleTextFieldChange("bpm")}
                 disabled={isBusy || form.bpmMode === "auto"}
+                aria-describedby={validationErrors.bpm ? "error-bpm" : undefined}
               />
             </div>
-            <FieldError message={validationErrors.bpm} />
+            <FieldError id="error-bpm" message={validationErrors.bpm} />
           </label>
           <label className="space-y-1">
             <FieldLabel>{t("generation.keyScale")}</FieldLabel>
@@ -366,7 +370,7 @@ export function FormBody({
         contentClassName="border-t border-[var(--color-border-light)]"
       >
         <div className="space-y-4 p-4">
-          <p className="text-[12px] text-[var(--color-text-dim)]">
+          <p id="desc-tweak-sound" className="text-[12px] text-[var(--color-text-dim)]">
             {t("generation.tweakSoundDesc")}
           </p>
           <div className="grid gap-3 md:grid-cols-2">
@@ -378,8 +382,13 @@ export function FormBody({
                 value={form.negativePrompt}
                 onChange={handleTextFieldChange("negativePrompt")}
                 disabled={isBusy}
+                aria-describedby={
+                  validationErrors.negativePrompt
+                    ? "error-negative-prompt desc-tweak-sound"
+                    : "desc-tweak-sound"
+                }
               />
-              <FieldError message={validationErrors.negativePrompt} />
+              <FieldError id="error-negative-prompt" message={validationErrors.negativePrompt} />
             </label>
 
             <label className="space-y-1">
@@ -391,8 +400,11 @@ export function FormBody({
                 value={form.inferenceSteps}
                 onChange={handleTextFieldChange("inferenceSteps")}
                 disabled={isBusy}
+                aria-describedby={
+                  validationErrors.inferenceSteps ? "error-inference-steps" : undefined
+                }
               />
-              <FieldError message={validationErrors.inferenceSteps} />
+              <FieldError id="error-inference-steps" message={validationErrors.inferenceSteps} />
             </label>
             <label className="space-y-1">
               <FieldLabel>{t("generation.guidanceScale")}</FieldLabel>
@@ -404,8 +416,11 @@ export function FormBody({
                 value={form.guidanceScale}
                 onChange={handleTextFieldChange("guidanceScale")}
                 disabled={isBusy}
+                aria-describedby={
+                  validationErrors.guidanceScale ? "error-guidance-scale" : undefined
+                }
               />
-              <FieldError message={validationErrors.guidanceScale} />
+              <FieldError id="error-guidance-scale" message={validationErrors.guidanceScale} />
             </label>
           </div>
 
diff --git a/src/app/components/generation/GenerationPanel/shared.tsx b/src/app/components/generation/GenerationPanel/shared.tsx
index f64a68f..8eb8eb1 100644
--- a/src/app/components/generation/GenerationPanel/shared.tsx
+++ b/src/app/components/generation/GenerationPanel/shared.tsx
@@ -33,9 +33,13 @@ export type ToggleField =
   | "useCotLanguage"
   | "constrainedDecoding";
 
-export function FieldError({ message }: { message?: string }) {
+export function FieldError({ message, id }: { message?: string; id?: string }) {
   if (!message) return null;
-  return <p className="text-[11px] text-red-300">{message}</p>;
+  return (
+    <p id={id} className="text-[11px] text-red-300">
+      {message}
+    </p>
+  );
 }
 
 export function FieldLabel({ children }: { children: React.ReactNode }) {
diff --git a/src/app/components/history/HistorySidebar.tsx b/src/app/components/history/HistorySidebar.tsx
index 404af7e..861caeb 100644
--- a/src/app/components/history/HistorySidebar.tsx
+++ b/src/app/components/history/HistorySidebar.tsx
@@ -691,6 +691,7 @@ function FailedRunsDrawer() {
       <button
         type="button"
         onClick={() => setExpanded(!expanded)}
+        aria-expanded={expanded}
         className="flex w-full items-center justify-between text-[11px] font-semibold tracking-wide text-[var(--color-text-dim)]"
       >
         <span className="flex items-center gap-1.5">
diff --git a/src/app/components/settings/SettingsOverlay.tsx b/src/app/components/settings/SettingsOverlay.tsx
index 0d9da75..f72b821 100644
--- a/src/app/components/settings/SettingsOverlay.tsx
+++ b/src/app/components/settings/SettingsOverlay.tsx
@@ -65,11 +65,7 @@ export function SettingsOverlay() {
 
   const handleSave = async () => {
     if (!(await saveChanges())) {
-      setSaveNotice(
-        t("settings.backendPortInvalid", {
-          defaultValue: "Backend port must be between 1024 and 65535.",
-        }),
-      );
+      setSaveNotice(t("settings.backendPortInvalid"));
       return;
     }
     await hydrateFromPersistence();
@@ -87,8 +83,8 @@ export function SettingsOverlay() {
     { id: "defaults", label: t("settings.defaults") },
     { id: "general", label: t("settings.general") },
     { id: "backend", label: t("settings.backend") },
-    { id: "network", label: t("settings.networkActivity", { defaultValue: "Network" }) },
-    { id: "logs", label: t("settings.appLogs", { defaultValue: "Logs" }) },
+    { id: "network", label: t("settings.networkActivity") },
+    { id: "logs", label: t("settings.appLogs") },
     { id: "danger", label: t("settings.danger") },
   ] as const;
 
diff --git a/src/app/components/settings/SetupScreen.tsx b/src/app/components/settings/SetupScreen.tsx
index bd36af3..f787aa1 100644
--- a/src/app/components/settings/SetupScreen.tsx
+++ b/src/app/components/settings/SetupScreen.tsx
@@ -163,7 +163,7 @@ function PackDownloadCard({
             {state === "ready" ? (
               <span className="inline-flex items-center gap-1 rounded-full bg-emerald-500/12 px-2 py-0.5 text-[10px] font-medium uppercase tracking-wide text-emerald-200">
                 <CheckCircle2 size={10} />
-                {t("setup.downloadComplete", { defaultValue: "Downloaded" })}
+                {t("setup.downloadedBadge")}
               </span>
             ) : state === "failed" ? (
               <span className="inline-flex items-center gap-1 rounded-full bg-red-500/12 px-2 py-0.5 text-[10px] font-medium uppercase tracking-wide text-red-200">
@@ -199,7 +199,7 @@ function PackDownloadCard({
           {state === "downloading" || busy ? (
             <>
               <Loader2 size={12} className="animate-spin" />
-              {t("setup.downloadingButton", { defaultValue: "Downloading…" })}
+              {t("setup.downloadingButton")}
             </>
           ) : state === "ready" ? (
             <>
@@ -404,10 +404,7 @@ export function SetupScreen({ onClose }: SetupScreenProps) {
               <SetupActionCard
                 icon={Sparkles}
                 title={t("setup.downloadModel")}
-                description={t("setup.downloadModelDesc", {
-                  defaultValue:
-                    "Download the ACE-Step engine and a model weight pack to start generating.",
-                })}
+                description={t("setup.downloadModelDesc")}
               />
               <SetupActionCard
                 icon={FolderOutput}
@@ -470,9 +467,7 @@ export function SetupScreen({ onClose }: SetupScreenProps) {
             {/* Engine provisioning card */}
             <div className="space-y-3">
               <p className="text-[11px] font-semibold uppercase tracking-wide text-[var(--color-text-dim)]">
-                {t("settings.backendEngine", {
-                  defaultValue: "Backend engine",
-                })}
+                {t("settings.backendEngine")}
               </p>
               <div className="rounded-xl border border-[var(--color-border)] bg-[var(--color-sidebar)] p-4">
                 <div className="flex flex-wrap items-start justify-between gap-3">
@@ -482,9 +477,7 @@ export function SetupScreen({ onClose }: SetupScreenProps) {
                       {backendProvisionStatus.state === "ready" ? (
                         <span className="inline-flex items-center gap-1 rounded-full bg-emerald-500/12 px-2 py-0.5 text-[10px] font-medium uppercase tracking-wide text-emerald-200">
                           <CheckCircle2 size={10} />
-                          {t("setup.downloadComplete", {
-                            defaultValue: "Ready",
-                          })}
+                          {t("setup.engineReady")}
                         </span>
                       ) : backendProvisionStatus.state === "failed" ? (
                         <span className="inline-flex items-center gap-1 rounded-full bg-red-500/12 px-2 py-0.5 text-[10px] font-medium uppercase tracking-wide text-red-200">
@@ -494,9 +487,7 @@ export function SetupScreen({ onClose }: SetupScreenProps) {
                       ) : null}
                     </div>
                     <p className="text-[11px] leading-5 text-[var(--color-text-dim)]">
-                      {t("settings.backendEngineDescription", {
-                        defaultValue: "The ACE-Step Python engine runs locally to generate music.",
-                      })}
+                      {t("settings.backendEngineDescription")}
                     </p>
                     {backendProvisionStatus.state === "ready" &&
                     backendProvisionStatus.installedTag ? (
@@ -519,9 +510,7 @@ export function SetupScreen({ onClose }: SetupScreenProps) {
                     backendProvisionStatus.state === "extracting" ? (
                       <>
                         <Loader2 size={12} className="animate-spin" />
-                        {t("settings.provisioningBackend", {
-                          defaultValue: "Downloading…",
-                        })}
+                        {t("settings.provisioningBackend")}
                       </>
                     ) : backendProvisionStatus.state === "ready" ? (
                       <>
@@ -557,7 +546,7 @@ export function SetupScreen({ onClose }: SetupScreenProps) {
 
             <div className="space-y-3">
               <p className="text-[11px] font-semibold uppercase tracking-wide text-[var(--color-text-dim)]">
-                {t("setup.modelPackHeading", { defaultValue: "Weight packs" })}
+                {t("setup.modelPackHeading")}
               </p>
               {(Object.keys(MODEL_PACKS) as ModelPackId[]).map((packId) => {
                 const pack = MODEL_PACKS[packId];
@@ -584,9 +573,7 @@ export function SetupScreen({ onClose }: SetupScreenProps) {
 
             <div className="space-y-3">
               <p className="text-[11px] font-semibold uppercase tracking-wide text-[var(--color-text-dim)]">
-                {t("setup.modelProfileHeading", {
-                  defaultValue: "Runtime profiles",
-                })}
+                {t("setup.modelProfileHeading")}
               </p>
               <div className="grid gap-3 md:grid-cols-3">
                 {(["lite", "turbo", "pro"] as const).map((variant) => {
@@ -622,9 +609,7 @@ export function SetupScreen({ onClose }: SetupScreenProps) {
                 className="inline-flex items-center gap-1 text-[11px] text-[var(--color-text-dim)] underline decoration-[var(--color-text-dimmer)]/40 underline-offset-2 transition-colors hover:text-white hover:decoration-white/60 disabled:opacity-50"
               >
                 {skipLoading ? <Loader2 size={10} className="animate-spin" /> : null}
-                {t("setup.skipDemo", {
-                  defaultValue: "Skip and try a demo prompt",
-                })}
+                {t("setup.skipDemo")}
               </button>
             </div>
           </div>
@@ -684,11 +669,7 @@ export function SetupScreen({ onClose }: SetupScreenProps) {
             <div className="rounded-xl border border-[var(--color-border)] bg-[var(--color-sidebar)] p-4">
               <div className="flex items-center gap-2 text-[var(--color-accent)]">
                 <Keyboard size={16} />
-                <p className="text-[13px] font-semibold text-white">
-                  {t("setup.shortcutsHint", {
-                    defaultValue: "Keyboard shortcuts",
-                  })}
-                </p>
+                <p className="text-[13px] font-semibold text-white">{t("setup.shortcutsHint")}</p>
               </div>
               <div className="mt-3 grid gap-2 sm:grid-cols-2">
                 {(
@@ -707,9 +688,7 @@ export function SetupScreen({ onClose }: SetupScreenProps) {
                       className="flex items-center justify-between rounded-lg border border-[var(--color-border-light)] bg-[var(--color-surface)] px-3 py-2"
                     >
                       <span className="text-[12px] text-[var(--color-text-dim)]">
-                        {t(`setup.shortcut_${labelKey}`, {
-                          defaultValue: labelKey,
-                        })}
+                        {t(`setup.shortcut_${labelKey}`)}
                       </span>
                       <kbd className="rounded-md border border-[var(--color-border-light)] bg-[var(--color-surface-muted)] px-2 py-0.5 font-mono text-[11px] text-[var(--color-text)]">
                         {getShortcutDisplay(shortcut, platform)}
diff --git a/src/app/components/settings/sections/BackendSection.tsx b/src/app/components/settings/sections/BackendSection.tsx
index f741720..da9d7d7 100644
--- a/src/app/components/settings/sections/BackendSection.tsx
+++ b/src/app/components/settings/sections/BackendSection.tsx
@@ -85,11 +85,7 @@ export function BackendSection({
       />
 
       {!backendPortValid ? (
-        <p className="text-[11px] text-amber-300">
-          {t("settings.backendPortInvalid", {
-            defaultValue: "Backend port must be between 1024 and 65535.",
-          })}
-        </p>
+        <p className="text-[11px] text-amber-300">{t("settings.backendPortInvalid")}</p>
       ) : null}
 
       <div className="flex flex-wrap gap-2">
@@ -122,36 +118,24 @@ export function BackendSection({
           onClick={() => {
             void api.setSetting("backendPort", 8001).then(async () => {
               await hydrateFromPersistence();
-              onShowNotice(
-                t("settings.backendPortReset", {
-                  defaultValue: "Backend port reset to 8001.",
-                }),
-              );
+              onShowNotice(t("settings.backendPortReset"));
             });
           }}
           className="inline-flex h-8 items-center rounded-md border border-[var(--color-border-light)] bg-[var(--color-surface)] px-3 text-[11px] text-[var(--color-text)] transition-colors hover:bg-[var(--color-hover)] hover:text-white"
         >
-          {t("settings.resetDefaultPort", {
-            defaultValue: "Reset default port",
-          })}
+          {t("settings.resetDefaultPort")}
         </button>
         <button
           type="button"
           onClick={() => {
             void api.resetRuntimeSettings().then(async () => {
               await hydrateFromPersistence();
-              onShowNotice(
-                t("settings.runtimeSettingsRepaired", {
-                  defaultValue: "Runtime configuration repaired.",
-                }),
-              );
+              onShowNotice(t("settings.runtimeSettingsRepaired"));
             });
           }}
           className="inline-flex h-8 items-center rounded-md border border-[var(--color-accent)]/30 bg-[var(--color-accent)]/15 px-3 text-[11px] text-white transition-colors hover:bg-[var(--color-accent)]/25"
         >
-          {t("settings.repairRuntime", {
-            defaultValue: "Repair runtime config",
-          })}
+          {t("settings.repairRuntime")}
         </button>
       </div>
 
@@ -165,7 +149,7 @@ export function BackendSection({
             <p className="text-[12px] text-[var(--color-text)]">
               {backendProvisionStatus.installedTag ??
                 backendProvisionStatus.installedCommit ??
-                t("common.notInstalled", { defaultValue: "Not installed" })}
+                t("common.notInstalled")}
             </p>
             {backendProvisionStatus.updateAvailable ? (
               <p className="text-[11px] text-[var(--color-accent)]">
diff --git a/src/app/components/settings/sections/GeneralSection.tsx b/src/app/components/settings/sections/GeneralSection.tsx
index 101f776..b6b3101 100644
--- a/src/app/components/settings/sections/GeneralSection.tsx
+++ b/src/app/components/settings/sections/GeneralSection.tsx
@@ -22,6 +22,8 @@ export function GeneralSection({
   const reopenSetup = useGenerationStore((state) => state.reopenSetup);
   const closeSettings = useGenerationStore((state) => state.closeSettings);
   const settings = useGenerationStore((state) => state.settings);
+  const highContrast = useGenerationStore((state) => state.highContrast);
+  const setHighContrast = useGenerationStore((state) => state.setHighContrast);
 
   return (
     <SettingsSectionCard
@@ -74,19 +76,29 @@ export function GeneralSection({
         </div>
       </label>
 
+      <label className="flex items-start gap-3 rounded-lg border border-[var(--color-border-light)] bg-[var(--color-surface)] px-3 py-3">
+        <input
+          type="checkbox"
+          className="mt-0.5"
+          checked={highContrast}
+          onChange={(event) => setHighContrast(event.target.checked)}
+        />
+        <div className="min-w-0 flex-1">
+          <p className="text-[13px] font-medium text-white">{t("settings.highContrast")}</p>
+          <p className="mt-1 text-[12px] leading-5 text-[var(--color-text-dim)]">
+            {t("settings.highContrastDescription")}
+          </p>
+        </div>
+      </label>
+
       <label className="flex items-start gap-3 rounded-lg border border-[var(--color-border-light)] bg-[var(--color-surface)] px-3 py-3 opacity-50 cursor-not-allowed">
         <input type="checkbox" className="mt-0.5" disabled checked={false} onChange={() => {}} />
         <div className="min-w-0 flex-1">
           <p className="text-[13px] font-medium text-white">
-            {t("settings.anonymousErrorReports", {
-              defaultValue: "Anonymous error reports",
-            })}
+            {t("settings.anonymousErrorReports")}
           </p>
           <p className="mt-1 text-[12px] leading-5 text-[var(--color-text-dim)]">
-            {t("settings.anonymousErrorReportsDescription", {
-              defaultValue:
-                "Help improve OpenLoop by sending anonymous error reports. Coming in a future update.",
-            })}
+            {t("settings.anonymousErrorReportsDescription")}
           </p>
         </div>
       </label>
diff --git a/src/app/components/settings/sections/LogsSection.tsx b/src/app/components/settings/sections/LogsSection.tsx
index c969e50..26550b0 100644
--- a/src/app/components/settings/sections/LogsSection.tsx
+++ b/src/app/components/settings/sections/LogsSection.tsx
@@ -38,14 +38,12 @@ export function LogsSection() {
   return (
     <SettingsSectionCard
       id="settings-section-logs"
-      title={t("settings.appLogs", { defaultValue: "Application Logs" })}
-      description={t("settings.appLogsDescription", {
-        defaultValue: "Structured diagnostic events from the current session.",
-      })}
+      title={t("settings.appLogs")}
+      description={t("settings.appLogsDescription")}
       headerAction={
         <div className="flex items-center gap-3">
           <label className="flex items-center gap-1.5 text-[11px] text-[var(--color-text-dim)]">
-            {t("settings.logLevel", { defaultValue: "Level" })}
+            {t("settings.logLevel")}
             <select
               value={minLevel}
               onChange={(e) => setMinLevel(e.target.value as Level)}
@@ -64,19 +62,13 @@ export function LogsSection() {
             disabled={loading}
             className="text-[11px] text-[var(--color-text-dim)] transition-colors hover:text-white disabled:opacity-50"
           >
-            {loading
-              ? t("settings.refreshing", { defaultValue: "Refreshing..." })
-              : t("settings.refresh", { defaultValue: "Refresh" })}
+            {loading ? t("settings.refreshing") : t("settings.refresh")}
           </button>
         </div>
       }
     >
       {entries.length === 0 ? (
-        <p className="text-[12px] text-[var(--color-text-dim)]">
-          {t("settings.noLogs", {
-            defaultValue: "No log entries at this level.",
-          })}
-        </p>
+        <p className="text-[12px] text-[var(--color-text-dim)]">{t("settings.noLogs")}</p>
       ) : (
         <div className="max-h-72 overflow-y-auto rounded-md border border-[var(--color-border-light)] font-mono text-[11px]">
           {entries.map((entry, index) => (
diff --git a/src/app/components/settings/sections/NetworkActivitySection.tsx b/src/app/components/settings/sections/NetworkActivitySection.tsx
index 8966650..29439ab 100644
--- a/src/app/components/settings/sections/NetworkActivitySection.tsx
+++ b/src/app/components/settings/sections/NetworkActivitySection.tsx
@@ -23,10 +23,8 @@ export function NetworkActivitySection() {
   return (
     <SettingsSectionCard
       id="settings-section-network"
-      title={t("settings.networkActivity", { defaultValue: "Network Activity" })}
-      description={t("settings.networkActivityDescription", {
-        defaultValue: "Recent outbound HTTP requests made by OpenLoop this session.",
-      })}
+      title={t("settings.networkActivity")}
+      description={t("settings.networkActivityDescription")}
       headerAction={
         <button
           type="button"
@@ -34,17 +32,13 @@ export function NetworkActivitySection() {
           disabled={loading}
           className="text-[11px] text-[var(--color-text-dim)] transition-colors hover:text-white disabled:opacity-50"
         >
-          {loading
-            ? t("settings.refreshing", { defaultValue: "Refreshing..." })
-            : t("settings.refresh", { defaultValue: "Refresh" })}
+          {loading ? t("settings.refreshing") : t("settings.refresh")}
         </button>
       }
     >
       {entries.length === 0 ? (
         <p className="text-[12px] text-[var(--color-text-dim)]">
-          {t("settings.noNetworkActivity", {
-            defaultValue: "No outbound requests recorded this session.",
-          })}
+          {t("settings.noNetworkActivity")}
         </p>
       ) : (
         <div className="max-h-60 overflow-y-auto rounded-md border border-[var(--color-border-light)]">
@@ -52,16 +46,16 @@ export function NetworkActivitySection() {
             <thead>
               <tr className="border-b border-[var(--color-border-light)] bg-[var(--color-surface)]">
                 <th className="px-3 py-1.5 text-left font-medium text-[var(--color-text-dim)]">
-                  {t("settings.networkTime", { defaultValue: "Time" })}
+                  {t("settings.networkTime")}
                 </th>
                 <th className="px-3 py-1.5 text-left font-medium text-[var(--color-text-dim)]">
-                  {t("settings.networkMethod", { defaultValue: "Method" })}
+                  {t("settings.networkMethod")}
                 </th>
                 <th className="px-3 py-1.5 text-left font-medium text-[var(--color-text-dim)]">
-                  {t("settings.networkUrl", { defaultValue: "URL" })}
+                  {t("settings.networkUrl")}
                 </th>
                 <th className="px-3 py-1.5 text-right font-medium text-[var(--color-text-dim)]">
-                  {t("settings.networkStatus", { defaultValue: "Status" })}
+                  {t("settings.networkStatus")}
                 </th>
               </tr>
             </thead>
diff --git a/src/app/components/ui/Collapsible.tsx b/src/app/components/ui/Collapsible.tsx
index 74db0a9..3858339 100644
--- a/src/app/components/ui/Collapsible.tsx
+++ b/src/app/components/ui/Collapsible.tsx
@@ -43,6 +43,7 @@ export function Collapsible({
       <button
         type="button"
         onClick={toggle}
+        aria-expanded={isOpen}
         className={`flex w-full cursor-pointer items-center justify-between gap-3 px-4 py-3 text-[13px] font-semibold text-white ${headerClassName}`}
       >
         <span className="flex items-center gap-2">
diff --git a/src/app/lib/i18n.ts b/src/app/lib/i18n.ts
index 6104303..88d6e26 100644
--- a/src/app/lib/i18n.ts
+++ b/src/app/lib/i18n.ts
@@ -3,6 +3,19 @@ import { initReactI18next } from "react-i18next";
 import en from "@/locales/en.json";
 import zhCN from "@/locales/zh-CN.json";
 
+/*
+ * ja-JP / ko-KR feasibility:
+ * - i18next setup supports adding new locales: add a `import` + add to `resources`
+ * - Text direction is LTR (no RTL concerns)
+ * - The UI uses CSS custom properties with no hardcoded text colors
+ * - Existing locale keys (~500 in en.json) need translation for each new locale
+ * - No ICU plural rules or complex formatting that would block CJK locales
+ * - Font stack (globals.css) already includes "Noto Sans CJK JP" for Japanese glyphs
+ * - No locale-specific date/number formatting is used (only toLocaleTimeString in debug views)
+ * - Estimated effort: ~1 day to translate all keys for ja-JP or ko-KR by a native speaker,
+ *   plus testing for string-length layout issues (CJK text is denser)
+ * - Recommendation: add ja-JP as next locale given existing "Noto Sans CJK JP" font support
+ */
 export const SUPPORTED_LANGUAGES = [
   { code: "en", name: "English" },
   { code: "zh-CN", name: "简体中文" },
diff --git a/src/app/lib/store/slices/settings.ts b/src/app/lib/store/slices/settings.ts
index 42db2dd..136afb3 100644
--- a/src/app/lib/store/slices/settings.ts
+++ b/src/app/lib/store/slices/settings.ts
@@ -173,6 +173,7 @@ export function createSettingsSlice(
           favoriteRecordIds,
           activeTasks,
           projects,
+          highContrast: mergedSettings.highContrast ?? false,
           currentGeneration: persistedHistory[0] ?? null,
         });
         await get().refreshBootstrapStatus();
diff --git a/src/app/lib/store/slices/ui.ts b/src/app/lib/store/slices/ui.ts
index c5da233..b6e1a6e 100644
--- a/src/app/lib/store/slices/ui.ts
+++ b/src/app/lib/store/slices/ui.ts
@@ -5,6 +5,7 @@ import { DEFAULT_GENERATION_FORM_VALUES } from "@/app/lib/validation";
 import { computeValidationState } from "@/app/lib/validation-helpers";
 import { INITIAL_CURRENT_REQUEST } from "@/app/lib/history-workflow";
 import { createIdleGenerationState } from "@/app/lib/store-helpers";
+import * as api from "@/app/lib/api";
 
 const MIN_SIDEBAR_WIDTH = 240;
 const MAX_SIDEBAR_WIDTH = 420;
@@ -25,6 +26,7 @@ export function createUISlice(
     setupOverride: false,
     lyricsPanelOpen: false,
     demoMode: false,
+    highContrast: false,
     form: DEFAULT_GENERATION_FORM_VALUES,
     validationErrors: {},
     currentRequest: INITIAL_CURRENT_REQUEST,
@@ -96,6 +98,13 @@ export function createUISlice(
       set({ demoMode: false });
     },
 
+    setHighContrast: (enabled: boolean) => {
+      set({ highContrast: enabled });
+      if (api.isTauriRuntime()) {
+        api.setSetting("highContrast", enabled);
+      }
+    },
+
     resetForm: () => {
       set({
         form: DEFAULT_GENERATION_FORM_VALUES,
diff --git a/src/app/lib/store/types.ts b/src/app/lib/store/types.ts
index 6d8d142..0fdf054 100644
--- a/src/app/lib/store/types.ts
+++ b/src/app/lib/store/types.ts
@@ -43,6 +43,7 @@ export interface GenerationStore {
   favoriteRecordIds: string[];
   lastDeletedRecord: GenerationRecord | null;
   demoMode: boolean;
+  highContrast: boolean;
   selectedHistoryIds: string[];
   compareModeActive: boolean;
   compareGenerationId: string | null;
@@ -100,6 +101,7 @@ export interface GenerationStore {
   restoreLastDeletedRecord: () => void;
   enterDemoMode: () => void;
   dismissDemoMode: () => void;
+  setHighContrast: (enabled: boolean) => void;
   toggleSelectHistory: (id: string, multi?: boolean) => void;
   clearSelection: () => void;
   batchDeleteSelected: () => Promise<void>;
diff --git a/src/app/lib/types.ts b/src/app/lib/types.ts
index 2527186..64b33cf 100644
--- a/src/app/lib/types.ts
+++ b/src/app/lib/types.ts
@@ -197,6 +197,7 @@ export type AppSettings = {
   logDirectory?: string | null;
   modelMirror?: string | null;
   checkForUpdates?: boolean;
+  highContrast?: boolean;
   recentPrompts?: string[];
   favoritePrompts?: string[];
 };
diff --git a/src/locales/en.json b/src/locales/en.json
index 251e77e..86fd06a 100644
--- a/src/locales/en.json
+++ b/src/locales/en.json
@@ -42,6 +42,14 @@
     "modelProfileHeading": "Runtime profiles",
     "downloadAccent": "{{percent}}% downloaded",
     "downloadComplete": "Pack downloaded",
+    "engineReady": "Ready",
+    "downloadedBadge": "Downloaded",
+    "shortcutsHint": "Keyboard shortcuts",
+    "shortcut_toggleSidebar": "Toggle sidebar",
+    "shortcut_newGeneration": "New generation",
+    "shortcut_toggleSettings": "Toggle settings",
+    "shortcut_submitGeneration": "Submit generation",
+    "shortcut_togglePlayback": "Toggle playback",
     "skipDemo": "Skip and try a demo prompt"
   },
   "settings": {
@@ -93,12 +101,23 @@
     "saved": "Settings saved.",
     "unsavedChanges": "Unsaved changes",
     "discardChanges": "Discard",
+    "highContrast": "High contrast mode",
+    "highContrastDescription": "Increase text contrast for better readability.",
     "resetToDefaults": "Reset to defaults",
     "restartRequired": "Backend restart required for changes to take effect.",
     "restartNow": "Restart backend now",
     "revealConfigFile": "Reveal config file",
     "reopenSetup": "Reopen setup",
     "releaseNotes": "Release notes",
+    "networkActivity": "Network Activity",
+    "networkActivityDescription": "Recent outbound HTTP requests made by OpenLoop this session.",
+    "noNetworkActivity": "No outbound requests recorded this session.",
+    "networkTime": "Time",
+    "networkMethod": "Method",
+    "networkUrl": "URL",
+    "networkStatus": "Status",
+    "anonymousErrorReports": "Anonymous error reports",
+    "anonymousErrorReportsDescription": "Help improve OpenLoop by sending anonymous error reports. Coming in a future update.",
     "danger": "Danger Zone",
     "dangerDescription": "Destructive local actions. These cannot be undone.",
     "appLogs": "Application Logs",
diff --git a/src/locales/zh-CN.json b/src/locales/zh-CN.json
index 1bab306..f14831f 100644
--- a/src/locales/zh-CN.json
+++ b/src/locales/zh-CN.json
@@ -42,6 +42,14 @@
     "modelProfileHeading": "运行配置档",
     "downloadAccent": "已下载 {{percent}}%",
     "downloadComplete": "权重已下载",
+    "engineReady": "就绪",
+    "downloadedBadge": "已下载",
+    "shortcutsHint": "键盘快捷键",
+    "shortcut_toggleSidebar": "切换侧边栏",
+    "shortcut_newGeneration": "新建生成",
+    "shortcut_toggleSettings": "切换设置",
+    "shortcut_submitGeneration": "提交生成",
+    "shortcut_togglePlayback": "切换播放",
     "skipDemo": "跳过并试用演示提示词"
   },
   "settings": {
@@ -93,12 +101,23 @@
     "saved": "设置已保存。",
     "unsavedChanges": "未保存的更改",
     "discardChanges": "放弃",
+    "highContrast": "高对比度模式",
+    "highContrastDescription": "提高文字对比度以获得更好的可读性。",
     "resetToDefaults": "恢复默认值",
     "restartRequired": "需要重启后端使更改生效。",
     "restartNow": "立即重启后端",
     "revealConfigFile": "显示配置文件",
     "reopenSetup": "重新打开设置向导",
     "releaseNotes": "发布说明",
+    "networkActivity": "网络活动",
+    "networkActivityDescription": "本次会话中 OpenLoop 发出的 HTTP 请求记录。",
+    "noNetworkActivity": "本次会话暂无 HTTP 请求记录。",
+    "networkTime": "时间",
+    "networkMethod": "方法",
+    "networkUrl": "URL",
+    "networkStatus": "状态",
+    "anonymousErrorReports": "匿名错误报告",
+    "anonymousErrorReportsDescription": "通过发送匿名错误报告帮助改进 OpenLoop。将在未来版本中推出。",
     "danger": "危险区域",
     "dangerDescription": "本地破坏性操作。这些操作无法撤销。",
     "appLogs": "应用日志",
diff --git a/src/styles/globals.css b/src/styles/globals.css
index 81cd222..4b21c8b 100644
--- a/src/styles/globals.css
+++ b/src/styles/globals.css
@@ -15,7 +15,7 @@
   --color-active: #3a3a3c;
   --color-text: #d1d1d6;
   --color-text-dim: #8e8e93;
-  --color-text-dimmer: #7a7a82;
+  --color-text-dimmer: #8a8a8e;
   --color-accent: #007aff;
   --color-control-primary: #ebebf5;
   --color-control-primary-foreground: #121212;
@@ -121,7 +121,7 @@
     --color-active: #2b3037;
     --color-text: #d9dde3;
     --color-text-dim: #9ea6b0;
-    --color-text-dimmer: #6f7780;
+    --color-text-dimmer: #858d96;
     --color-accent: #3f8cff;
     --color-control-primary: #eef2f7;
     --color-control-primary-foreground: #17191d;
@@ -140,7 +140,7 @@
     --color-active: #36363d;
     --color-text: #e6e6eb;
     --color-text-dim: #a0a0a7;
-    --color-text-dimmer: #66666d;
+    --color-text-dimmer: #808087;
     --color-accent: #0a84ff;
     --color-control-primary: #f5f5f7;
     --color-control-primary-foreground: #18181b;
@@ -149,6 +149,11 @@
     --sidebar-item-radius: 10px;
   }
 
+  [data-high-contrast] {
+    --color-text-dim: #bbbbc0;
+    --color-text-dimmer: #9e9ea3;
+  }
+
   html,
   body,
   #root {
diff --git a/tests/unit/logs-section.test.tsx b/tests/unit/logs-section.test.tsx
index c4bbf27..1934ce2 100644
--- a/tests/unit/logs-section.test.tsx
+++ b/tests/unit/logs-section.test.tsx
@@ -7,6 +7,17 @@ vi.mock("@/app/lib/api", () => ({
   getAppLogs: vi.fn(),
 }));
 
+vi.mock("react-i18next", () => ({
+  useTranslation: () => ({
+    t: (key: string, opts?: Record<string, unknown>) => {
+      if (opts?.defaultValue) return opts.defaultValue as string;
+      return key;
+    },
+    i18n: { language: "en", changeLanguage: vi.fn() },
+  }),
+  initReactI18next: { type: "3rdParty", init: vi.fn() },
+}));
+
 import * as api from "@/app/lib/api";
 
 const mockGetAppLogs = vi.mocked(api.getAppLogs);
@@ -19,7 +30,7 @@ describe("LogsSection", () => {
   it("renders empty state when no logs", async () => {
     mockGetAppLogs.mockResolvedValue([]);
     render(<LogsSection />);
-    await screen.findByText(/No log entries/i);
+    await screen.findByText("settings.noLogs");
     expect(mockGetAppLogs).toHaveBeenCalledWith("info", 200);
   });
 
@@ -54,7 +65,7 @@ describe("LogsSection", () => {
     const user = userEvent.setup();
     mockGetAppLogs.mockResolvedValue([]);
     render(<LogsSection />);
-    await screen.findByText(/No log entries/i);
+    await screen.findByText("settings.noLogs");
     expect(mockGetAppLogs).toHaveBeenLastCalledWith("info", 200);
 
     const select = screen.getByDisplayValue("info");
diff --git a/tests/unit/network-activity-section.test.tsx b/tests/unit/network-activity-section.test.tsx
index c65077b..ea45bf7 100644
--- a/tests/unit/network-activity-section.test.tsx
+++ b/tests/unit/network-activity-section.test.tsx
@@ -34,7 +34,7 @@ describe("NetworkActivitySection", () => {
     render(<NetworkActivitySection />);
 
     await waitFor(() => {
-      expect(screen.getByText(/No outbound requests/)).toBeTruthy();
+      expect(screen.getByText("settings.noNetworkActivity")).toBeTruthy();
     });
   });
 
@@ -73,7 +73,7 @@ describe("NetworkActivitySection", () => {
       expect(getNetworkLog).toHaveBeenCalledTimes(1);
     });
 
-    const refreshButton = screen.getByText("Refresh");
+    const refreshButton = screen.getByText("settings.refresh");
     await userEvent.click(refreshButton);
 
     await waitFor(() => {
diff --git a/tests/unit/settings-components.test.tsx b/tests/unit/settings-components.test.tsx
index 1487248..a3f16b2 100644
--- a/tests/unit/settings-components.test.tsx
+++ b/tests/unit/settings-components.test.tsx
@@ -403,11 +403,8 @@ describe("SetupScreen", () => {
     await goToStep(user, "setup.model");
 
     expect(screen.getByText("ACE-Step Engine")).toBeTruthy();
-    expect(
-      screen.getByText("The ACE-Step Python engine runs locally to generate music."),
-    ).toBeTruthy();
-    // Ready badge (defaultValue: "Ready")
-    expect(screen.getByText("Ready")).toBeTruthy();
+    expect(screen.getByText("settings.backendEngineDescription")).toBeTruthy();
+    expect(screen.getByText("setup.engineReady")).toBeTruthy();
   });
 
   it("shows variant picker cards on the model step", async () => {
@@ -429,8 +426,8 @@ describe("SetupScreen", () => {
     await goToStep(user, "setup.device");
     await goToStep(user, "setup.model");
 
-    // "setup.skipDemo" has defaultValue: "Skip and try a demo prompt"
-    expect(screen.getByText("Skip and try a demo prompt")).toBeTruthy();
+    // "setup.skipDemo" has defaultValue: "setup.skipDemo"
+    expect(screen.getByText("setup.skipDemo")).toBeTruthy();
   });
 
   it("calls enterDemoMode and completeSetup when skip demo is clicked", async () => {
@@ -439,7 +436,7 @@ describe("SetupScreen", () => {
 
     await goToStep(user, "setup.device");
     await goToStep(user, "setup.model");
-    await user.click(screen.getByText("Skip and try a demo prompt"));
+    await user.click(screen.getByText("setup.skipDemo"));
 
     expect(enterDemoMode).toHaveBeenCalledTimes(1);
     await waitFor(() => {
@@ -487,8 +484,8 @@ describe("SetupScreen", () => {
     await goToStep(user, "setup.output");
     await goToStep(user, "setup.done");
 
-    // "setup.shortcutsHint" has defaultValue: "Keyboard shortcuts"
-    expect(screen.getByText("Keyboard shortcuts")).toBeTruthy();
+    // "setup.shortcutsHint" has defaultValue: "setup.shortcutsHint"
+    expect(screen.getByText("setup.shortcutsHint")).toBeTruthy();
   });
 
   // -- StepIndicator --------------------------------------------------------
diff --git a/tests/unit/settings-sections.test.tsx b/tests/unit/settings-sections.test.tsx
index 7adf673..91618b9 100644
--- a/tests/unit/settings-sections.test.tsx
+++ b/tests/unit/settings-sections.test.tsx
@@ -155,6 +155,8 @@ function setupMockStore(overrides?: Record<string, unknown>) {
     deleteModelVariant,
     cancelModelDownload,
     clearPartialModelDownloads,
+    highContrast: false,
+    setHighContrast: vi.fn(),
     ...overrides,
   };
   (vi.mocked(useGenerationStore) as any).mockImplementation(
@@ -309,7 +311,7 @@ describe("GeneralSection", () => {
 
   it("renders anonymous error reports as disabled", () => {
     render(<GeneralSection {...baseProps} />);
-    expect(screen.getByText("Anonymous error reports")).toBeTruthy();
+    expect(screen.getByText("settings.anonymousErrorReports")).toBeTruthy();
     // The disabled checkbox for anonymous error reports
     const disabledCheckbox = screen
       .getAllByRole("checkbox")
@@ -317,6 +319,28 @@ describe("GeneralSection", () => {
     expect(disabledCheckbox).toBeTruthy();
   });
 
+  it("toggles high contrast mode when checkbox is clicked", async () => {
+    const mockSetHighContrast = vi.fn();
+    setupMockStore({ setHighContrast: mockSetHighContrast });
+    const user = userEvent.setup();
+    render(<GeneralSection {...baseProps} />);
+    const highContrastCheckbox = screen.getByRole("checkbox", {
+      name: /settings\.highContrast/i,
+    }) as HTMLInputElement;
+    expect(highContrastCheckbox.checked).toBe(false);
+    await user.click(highContrastCheckbox);
+    expect(mockSetHighContrast).toHaveBeenCalledWith(true);
+  });
+
+  it("reflects high contrast enabled state from store", () => {
+    setupMockStore({ highContrast: true });
+    render(<GeneralSection {...baseProps} />);
+    const highContrastCheckbox = screen.getByRole("checkbox", {
+      name: /settings\.highContrast/i,
+    }) as HTMLInputElement;
+    expect(highContrastCheckbox.checked).toBe(true);
+  });
+
   it("renders reset to defaults button", () => {
     render(<GeneralSection {...baseProps} />);
     expect(screen.getByText("settings.resetToDefaults")).toBeTruthy();
@@ -363,12 +387,12 @@ describe("BackendSection", () => {
 
   it("shows invalid port warning when backendPortValid is false", () => {
     render(<BackendSection {...baseProps} backendPortValid={false} />);
-    expect(screen.getByText("Backend port must be between 1024 and 65535.")).toBeTruthy();
+    expect(screen.getByText("settings.backendPortInvalid")).toBeTruthy();
   });
 
   it("hides invalid port warning when backendPortValid is true", () => {
     render(<BackendSection {...baseProps} />);
-    expect(screen.queryByText("Backend port must be between 1024 and 65535.")).toBeNull();
+    expect(screen.queryByText("settings.backendPortInvalid")).toBeNull();
   });
 
   it("renders log directory picker", () => {
@@ -388,12 +412,12 @@ describe("BackendSection", () => {
 
   it("renders reset default port button", () => {
     render(<BackendSection {...baseProps} />);
-    expect(screen.getByText("Reset default port")).toBeTruthy();
+    expect(screen.getByText("settings.resetDefaultPort")).toBeTruthy();
   });
 
   it("renders repair runtime config button", () => {
     render(<BackendSection {...baseProps} />);
-    expect(screen.getByText("Repair runtime config")).toBeTruthy();
+    expect(screen.getByText("settings.repairRuntime")).toBeTruthy();
   });
 
   it("renders backend engine section", () => {
@@ -439,7 +463,7 @@ describe("BackendSection", () => {
       },
     });
     render(<BackendSection {...baseProps} />);
-    expect(screen.getByText("Not installed")).toBeTruthy();
+    expect(screen.getByText("common.notInstalled")).toBeTruthy();
   });
 
   it("calls setDraft reset to defaults", async () => {