feat(i18n): localize EffectsChainEditor and built-in preset names

- Effect type labels (Chorus/Flanger, Reverb, Delay, Compressor, Gain,
  High-Pass, Low-Pass, Pitch Shift) and every param label (LFO speed,
  Modulation depth, Threshold, Ratio, etc.) go through
  `effects.types.<type>.{label,params.<param>}` with the backend string
  as defaultValue fallback.
- Chain-level controls: "Load preset…", "Add effect…", "Clear",
  Power/Remove button titles.
- Built-in preset names + descriptions (Robotic, Radio, Echo Chamber,
  Deep Voice) are translated client-side; user-created presets keep
  their original names.

Backend keeps returning English — frontend intercepts and translates
via key lookup, defaulting to the backend string so unknown
effects/params don't break.

Co-Authored-By: Claude Opus 4.7 (1M context) <[email protected]>

app/src/components/Effects/EffectsChainEditor.tsx

@@ -18,6 +18,7 @@ import { CSS } from '@dnd-kit/utilities';
 import { useQuery } from '@tanstack/react-query';
 import { ChevronDown, ChevronRight, GripVertical, Plus, Power, Trash2 } from 'lucide-react';
 import { useCallback, useMemo, useRef, useState } from 'react';
+import { useTranslation } from 'react-i18next';
 import { Button } from '@/components/ui/button';
 import { Label } from '@/components/ui/label';
 import {
@@ -55,6 +56,7 @@ export function EffectsChainEditor({
   compact = false,
   showPresets = true,
 }: EffectsChainEditorProps) {
+  const { t } = useTranslation();
   const [expandedId, setExpandedId] = useState<string | null>(null);
 
   // Maintain stable IDs for each effect across renders.
@@ -177,17 +179,27 @@ export function EffectsChainEditor({
             }}
           >
             <SelectTrigger className="h-8 flex-1 text-xs focus:ring-0 focus:ring-offset-0">
-              <SelectValue placeholder="Load preset..." />
+              <SelectValue placeholder={t('effects.chain.loadPreset')} />
             </SelectTrigger>
             <SelectContent>
-              {presets?.map((p) => (
-                <SelectItem key={p.id} value={p.id}>
-                  {p.name}
-                  {p.description && (
-                    <span className="ml-1 text-muted-foreground">- {p.description}</span>
-                  )}
-                </SelectItem>
-              ))}
+              {presets?.map((p) => {
+                const name = p.is_builtin
+                  ? t(`effects.builtinPresets.${p.name}.name`, { defaultValue: p.name })
+                  : p.name;
+                const description = p.is_builtin
+                  ? t(`effects.builtinPresets.${p.name}.description`, {
+                      defaultValue: p.description ?? '',
+                    })
+                  : p.description;
+                return (
+                  <SelectItem key={p.id} value={p.id}>
+                    {name}
+                    {description && (
+                      <span className="ml-1 text-muted-foreground">- {description}</span>
+                    )}
+                  </SelectItem>
+                );
+              })}
             </SelectContent>
           </Select>
 
@@ -198,7 +210,7 @@ export function EffectsChainEditor({
               className="h-8 px-2 text-xs text-muted-foreground"
               onClick={clearAll}
             >
-              Clear
+              {t('effects.chain.clear')}
             </Button>
           )}
         </div>
@@ -229,12 +241,12 @@ export function EffectsChainEditor({
         <Select onValueChange={addEffect}>
           <SelectTrigger className="h-8 border-dashed text-xs text-muted-foreground focus:ring-0 focus:ring-offset-0">
             <Plus className="mr-1 h-3.5 w-3.5" />
-            <SelectValue placeholder="Add effect..." />
+            <SelectValue placeholder={t('effects.chain.addEffect')} />
           </SelectTrigger>
           <SelectContent>
             {availableEffects.effects.map((e) => (
               <SelectItem key={e.type} value={e.type}>
-                {e.label}
+                {t(`effects.types.${e.type}.label`, { defaultValue: e.label })}
               </SelectItem>
             ))}
           </SelectContent>
@@ -270,6 +282,7 @@ function SortableEffectItem({
   onToggleEnabled,
   onUpdateParam,
 }: SortableEffectItemProps) {
+  const { t } = useTranslation();
   const { attributes, listeners, setNodeRef, transform, transition, isDragging } = useSortable({
     id,
   });
@@ -280,7 +293,9 @@ function SortableEffectItem({
     zIndex: isDragging ? 10 : undefined,
   };
 
-  const label = effectDef?.label ?? effect.type;
+  const label = t(`effects.types.${effect.type}.label`, {
+    defaultValue: effectDef?.label ?? effect.type,
+  });
 
   return (
     <div
@@ -328,7 +343,7 @@ function SortableEffectItem({
             effect.enabled ? 'text-primary' : 'text-muted-foreground hover:text-foreground',
           )}
           onClick={onToggleEnabled}
-          title={effect.enabled ? 'Disable' : 'Enable'}
+          title={effect.enabled ? t('effects.chain.disable') : t('effects.chain.enable')}
         >
           <Power className="h-3.5 w-3.5" />
         </button>
@@ -337,7 +352,7 @@ function SortableEffectItem({
           type="button"
           className="p-0.5 text-muted-foreground hover:text-destructive"
           onClick={onRemove}
-          title="Remove"
+          title={t('effects.chain.remove')}
         >
           <Trash2 className="h-3.5 w-3.5" />
         </button>
@@ -352,7 +367,9 @@ function SortableEffectItem({
               <div key={paramName} className="space-y-1">
                 <div className="flex items-center justify-between">
                   <Label className="text-[11px] text-muted-foreground">
-                    {paramDef.description}
+                    {t(`effects.types.${effect.type}.params.${paramName}`, {
+                      defaultValue: paramDef.description,
+                    })}
                   </Label>
                   <span className="text-[11px] font-mono tabular-nums text-foreground">
                     {currentValue.toFixed(

app/src/components/EffectsTab/EffectsDetail.tsx

@@ -97,6 +97,18 @@ export function EffectsDetail() {
 
   const isEditing = !!selectedPresetId || isCreatingNew;
   const isBuiltIn = preset?.is_builtin ?? false;
+  const presetName = preset
+    ? preset.is_builtin
+      ? t(`effects.builtinPresets.${preset.name}.name`, { defaultValue: preset.name })
+      : preset.name
+    : '';
+  const presetDescription = preset
+    ? preset.is_builtin
+      ? t(`effects.builtinPresets.${preset.name}.description`, {
+          defaultValue: preset.description ?? '',
+        })
+      : preset.description
+    : '';
 
   async function handlePreview() {
     if (!previewGenId || workingChain.length === 0) return;
@@ -184,7 +196,8 @@ export function EffectsDetail() {
   }
 
   function handleSaveAsNew() {
-    setSaveAsName(t('effects.saveAs.suggestedName', { name }));
+    const sourceName = isBuiltIn ? presetName : name;
+    setSaveAsName(t('effects.saveAs.suggestedName', { name: sourceName }));
     setSaveAsDescription(description);
     setSaveAsDialogOpen(true);
   }
@@ -257,7 +270,7 @@ export function EffectsDetail() {
           {isCreatingNew
             ? t('effects.detail.newTitle')
             : isBuiltIn
-              ? preset?.name
+              ? presetName
               : t('effects.detail.editTitle')}
         </h2>
         <div className="flex items-center gap-2">
@@ -334,8 +347,8 @@ export function EffectsDetail() {
           </div>
         )}
 
-        {isBuiltIn && preset?.description && (
-          <p className="text-sm text-muted-foreground">{preset.description}</p>
+        {isBuiltIn && presetDescription && (
+          <p className="text-sm text-muted-foreground">{presetDescription}</p>
         )}
 
         <EffectsChainEditor value={workingChain} onChange={setWorkingChain} showPresets={false} />

app/src/components/EffectsTab/EffectsList.tsx

@@ -124,6 +124,14 @@ function PresetCard({
 }) {
   const { t } = useTranslation();
   const effectCount = preset.effects_chain.length;
+  const name = preset.is_builtin
+    ? t(`effects.builtinPresets.${preset.name}.name`, { defaultValue: preset.name })
+    : preset.name;
+  const description = preset.is_builtin
+    ? t(`effects.builtinPresets.${preset.name}.description`, {
+        defaultValue: preset.description ?? '',
+      })
+    : preset.description;
 
   return (
     <button
@@ -140,7 +148,7 @@ function PresetCard({
         <Wand2
           className={cn('h-4 w-4 shrink-0', isSelected ? 'text-accent' : 'text-muted-foreground')}
         />
-        <span className="text-sm font-medium truncate">{preset.name}</span>
+        <span className="text-sm font-medium truncate">{name}</span>
         {preset.is_builtin && (
           <span className="text-[10px] bg-muted text-muted-foreground px-1.5 py-0.5 rounded-full shrink-0">
             {t('effects.badge.builtin')}
@@ -148,7 +156,7 @@ function PresetCard({
         )}
       </div>
       <p className="text-xs text-muted-foreground mt-1 line-clamp-1 pl-6">
-        {preset.description || t('effects.noDescription')}
+        {description || t('effects.noDescription')}
       </p>
       <div className="flex items-center gap-2 mt-1.5 pl-6">
         <span className="text-[10px] text-muted-foreground">

app/src/i18n/locales/en/translation.json

@@ -90,6 +90,95 @@
       "deleteFailed": "Failed to delete",
       "previewFailed": "Preview failed",
       "nameRequired": "Name required"
+    },
+    "chain": {
+      "loadPreset": "Load preset…",
+      "addEffect": "Add effect…",
+      "clear": "Clear",
+      "enable": "Enable",
+      "disable": "Disable",
+      "remove": "Remove"
+    },
+    "types": {
+      "chorus": {
+        "label": "Chorus / Flanger",
+        "params": {
+          "rate_hz": "LFO speed (Hz)",
+          "depth": "Modulation depth",
+          "feedback": "Feedback amount",
+          "centre_delay_ms": "Centre delay (ms)",
+          "mix": "Wet/dry mix"
+        }
+      },
+      "reverb": {
+        "label": "Reverb",
+        "params": {
+          "room_size": "Room size",
+          "damping": "High frequency damping",
+          "wet_level": "Wet level",
+          "dry_level": "Dry level",
+          "width": "Stereo width"
+        }
+      },
+      "delay": {
+        "label": "Delay",
+        "params": {
+          "delay_seconds": "Delay time (seconds)",
+          "feedback": "Feedback amount",
+          "mix": "Wet/dry mix"
+        }
+      },
+      "compressor": {
+        "label": "Compressor",
+        "params": {
+          "threshold_db": "Threshold (dB)",
+          "ratio": "Compression ratio",
+          "attack_ms": "Attack time (ms)",
+          "release_ms": "Release time (ms)"
+        }
+      },
+      "gain": {
+        "label": "Gain",
+        "params": {
+          "gain_db": "Gain (dB)"
+        }
+      },
+      "highpass": {
+        "label": "High-Pass Filter",
+        "params": {
+          "cutoff_frequency_hz": "Cutoff frequency (Hz)"
+        }
+      },
+      "lowpass": {
+        "label": "Low-Pass Filter",
+        "params": {
+          "cutoff_frequency_hz": "Cutoff frequency (Hz)"
+        }
+      },
+      "pitch_shift": {
+        "label": "Pitch Shift",
+        "params": {
+          "semitones": "Semitones to shift"
+        }
+      }
+    },
+    "builtinPresets": {
+      "Robotic": {
+        "name": "Robotic",
+        "description": "Metallic robotic voice (flanger with slow LFO and high feedback)"
+      },
+      "Radio": {
+        "name": "Radio",
+        "description": "Thin AM-radio voice with band-pass filtering and light compression"
+      },
+      "Echo Chamber": {
+        "name": "Echo Chamber",
+        "description": "Spacious reverb with trailing echo"
+      },
+      "Deep Voice": {
+        "name": "Deep Voice",
+        "description": "Lower pitch with added warmth"
+      }
     }
   },
   "stories": {

app/src/i18n/locales/zh-CN/translation.json

@@ -90,6 +90,95 @@
       "deleteFailed": "删除失败",
       "previewFailed": "预览失败",
       "nameRequired": "请输入名称"
+    },
+    "chain": {
+      "loadPreset": "加载预设……",
+      "addEffect": "添加效果……",
+      "clear": "清空",
+      "enable": "启用",
+      "disable": "禁用",
+      "remove": "移除"
+    },
+    "types": {
+      "chorus": {
+        "label": "合唱 / 镶边",
+        "params": {
+          "rate_hz": "LFO 速度(Hz)",
+          "depth": "调制深度",
+          "feedback": "反馈量",
+          "centre_delay_ms": "中心延迟(毫秒)",
+          "mix": "干湿混合"
+        }
+      },
+      "reverb": {
+        "label": "混响",
+        "params": {
+          "room_size": "房间大小",
+          "damping": "高频阻尼",
+          "wet_level": "湿声电平",
+          "dry_level": "干声电平",
+          "width": "立体声宽度"
+        }
+      },
+      "delay": {
+        "label": "延迟",
+        "params": {
+          "delay_seconds": "延迟时间(秒)",
+          "feedback": "反馈量",
+          "mix": "干湿混合"
+        }
+      },
+      "compressor": {
+        "label": "压缩器",
+        "params": {
+          "threshold_db": "阈值(dB)",
+          "ratio": "压缩比",
+          "attack_ms": "起音时间(毫秒)",
+          "release_ms": "释放时间(毫秒)"
+        }
+      },
+      "gain": {
+        "label": "增益",
+        "params": {
+          "gain_db": "增益(dB)"
+        }
+      },
+      "highpass": {
+        "label": "高通滤波器",
+        "params": {
+          "cutoff_frequency_hz": "截止频率(Hz)"
+        }
+      },
+      "lowpass": {
+        "label": "低通滤波器",
+        "params": {
+          "cutoff_frequency_hz": "截止频率(Hz)"
+        }
+      },
+      "pitch_shift": {
+        "label": "音高变换",
+        "params": {
+          "semitones": "半音移动"
+        }
+      }
+    },
+    "builtinPresets": {
+      "Robotic": {
+        "name": "机器人",
+        "description": "金属机器人嗓音(慢速 LFO 加高反馈的镶边效果)"
+      },
+      "Radio": {
+        "name": "收音机",
+        "description": "带通滤波加轻度压缩的 AM 收音机薄嗓音"
+      },
+      "Echo Chamber": {
+        "name": "回声室",
+        "description": "宽广的混响加尾随回声"
+      },
+      "Deep Voice": {
+        "name": "低沉嗓音",
+        "description": "降低音高并增添温暖"
+      }
     }
   },
   "stories": {