implemented 15,12,18 didn't check 18

frontend/src/components/ExportDialog.tsx

@@ -1,13 +1,16 @@
 import { useState, useCallback } from 'react';
 import { useEditorStore } from '../store/editorStore';
-import { Download, Loader2, Zap, Cog, Info } from 'lucide-react';
+import { Download, Loader2, Zap, Cog, Info, Volume2 } from 'lucide-react';
 import type { ExportOptions } from '../types/project';
 
 export default function ExportDialog() {
-  const { videoPath, words, cutRanges, muteRanges, gainRanges, speedRanges, globalGainDb, isExporting, exportProgress, backendUrl, setExporting, getKeepSegments } =
+  const { videoPath, words, cutRanges, muteRanges, gainRanges, speedRanges, globalGainDb, isExporting, exportProgress, backendUrl, setExporting, setExportedAudioPath, getKeepSegments } =
     useEditorStore();
 
   const hasCuts = cutRanges.length > 0;
+  const [isNormalizing, setIsNormalizing] = useState(false);
+  const [normalizeTarget, setNormalizeTarget] = useState(-14);
+  const [normalizeResult, setNormalizeResult] = useState<string | null>(null);
 
   const [options, setOptions] = useState<Omit<ExportOptions, 'outputPath'>>({
     mode: 'fast',
@@ -78,6 +81,41 @@ export default function ExportDialog() {
     }
   }, [videoPath, options, backendUrl, setExporting, getKeepSegments, cutRanges, muteRanges, gainRanges, speedRanges, globalGainDb, words]);
 
+  const handleNormalize = useCallback(async () => {
+    if (!videoPath) return;
+    setIsNormalizing(true);
+    setNormalizeResult(null);
+    try {
+      const res = await fetch(`${backendUrl}/audio/normalize`, {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({
+          input_path: videoPath,
+          target_lufs: normalizeTarget,
+          output_path: '',
+        }),
+      });
+      if (!res.ok) {
+        let detail = res.statusText;
+        try {
+          const body = await res.json();
+          if (body?.detail) detail = String(body.detail);
+        } catch {
+          // Keep statusText fallback
+        }
+        throw new Error(detail);
+      }
+      const data = await res.json();
+      setExportedAudioPath(data.output_path);
+      setNormalizeResult(`Normalized to ${data.target_lufs} LUFS → ${data.output_path.split('/').pop() || 'done'}`);
+    } catch (err) {
+      console.error('Normalize error:', err);
+      setNormalizeResult(`Error: ${err instanceof Error ? err.message : 'Normalization failed'}`);
+    } finally {
+      setIsNormalizing(false);
+    }
+  }, [videoPath, backendUrl, normalizeTarget, setExportedAudioPath]);
+
   return (
     <div className="p-4 space-y-5">
       <h3 className="text-sm font-semibold">Export Video</h3>
@@ -129,6 +167,46 @@ export default function ExportDialog() {
         ]}
       />
 
+      {/* Audio normalization */}
+      <div className="space-y-2 border-t border-editor-border pt-3">
+        <h4 className="text-xs font-semibold flex items-center gap-1.5">
+          <Volume2 className="w-3.5 h-3.5" />
+          Audio Normalization
+        </h4>
+        <p className="text-[10px] text-editor-text-muted leading-relaxed">
+          Normalize loudness to a target LUFS level. YouTube uses <strong>-14 LUFS</strong>,
+          Spotify uses <strong>-16 LUFS</strong>, broadcast uses <strong>-23 LUFS</strong>.
+        </p>
+        <div className="flex items-center gap-2">
+          <select
+            value={normalizeTarget}
+            onChange={(e) => setNormalizeTarget(Number(e.target.value))}
+            className="flex-1 px-2 py-1.5 text-xs bg-editor-surface border border-editor-border rounded focus:outline-none focus:border-editor-accent"
+          >
+            <option value={-14}>YouTube (-14 LUFS)</option>
+            <option value={-16}>Spotify (-16 LUFS)</option>
+            <option value={-23}>Broadcast (-23 LUFS)</option>
+            <option value={-11}>Loud (-11 LUFS)</option>
+            <option value={-9}>Very Loud (-9 LUFS)</option>
+          </select>
+          <button
+            onClick={handleNormalize}
+            disabled={isNormalizing || !videoPath}
+            className="flex items-center gap-1.5 px-3 py-1.5 text-xs rounded bg-editor-accent/20 text-editor-accent hover:bg-editor-accent/30 disabled:opacity-40 transition-colors"
+          >
+            {isNormalizing ? (
+              <Loader2 className="w-3 h-3 animate-spin" />
+            ) : (
+              <Volume2 className="w-3 h-3" />
+            )}
+            {isNormalizing ? 'Normalizing...' : 'Normalize'}
+          </button>
+        </div>
+        {normalizeResult && (
+          <p className="text-[10px] text-editor-success">{normalizeResult}</p>
+        )}
+      </div>
+
       {/* Audio enhancement */}
       <label className="flex items-center gap-2 cursor-pointer">
         <input