refactor: move effects panel from global to per-track

- Added showEffects property to Track type
- Added "E" button with Sparkles icon to toggle per-track effects
- Effects panel now appears below each track when toggled
- Removed global EffectsPanel from AudioEditor
- Updated useMultiTrack to persist showEffects state
- Streamlined workflow: both automation and effects are now per-track

This aligns the UX with professional DAWs like Ableton Live, where
effects and automation are track-scoped rather than global.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

components/editor/AudioEditor.tsx

@@ -14,7 +14,6 @@ import { useEffectChain } from '@/lib/hooks/useEffectChain';
 import { useToast } from '@/components/ui/Toast';
 import { TrackList } from '@/components/tracks/TrackList';
 import { ImportTrackDialog } from '@/components/tracks/ImportTrackDialog';
-import { EffectsPanel } from '@/components/effects/EffectsPanel';
 import { formatDuration } from '@/lib/audio/decoder';
 import { useHistory } from '@/lib/hooks/useHistory';
 import { useRecording } from '@/lib/hooks/useRecording';
@@ -40,8 +39,6 @@ export function AudioEditor() {
   const [punchOutTime, setPunchOutTime] = React.useState(0);
   const [overdubEnabled, setOverdubEnabled] = React.useState(false);
   const [settingsDialogOpen, setSettingsDialogOpen] = React.useState(false);
-  const [effectsPanelHeight, setEffectsPanelHeight] = React.useState(300);
-  const [effectsPanelVisible, setEffectsPanelVisible] = React.useState(false);
 
   const { addToast } = useToast();
 
@@ -816,24 +813,6 @@ export function AudioEditor() {
               trackLevels={trackLevels}
             />
           </div>
-
-          {/* Effects Panel - Global Folding State, Collapsed when no track */}
-          <EffectsPanel
-            track={selectedTrack || null}
-            visible={selectedTrack ? effectsPanelVisible : false}
-            height={effectsPanelHeight}
-            onToggleVisible={() => {
-              if (selectedTrack) {
-                setEffectsPanelVisible(!effectsPanelVisible);
-              }
-            }}
-            onResizeHeight={setEffectsPanelHeight}
-            onAddEffect={handleAddEffect}
-            onToggleEffect={handleToggleEffect}
-            onRemoveEffect={handleRemoveEffect}
-            onUpdateEffect={handleUpdateEffect}
-            onToggleEffectExpanded={handleToggleEffectExpanded}
-          />
         </main>
       </div>
 

components/tracks/Track.tsx

@@ -1,7 +1,7 @@
 'use client';
 
 import * as React from 'react';
-import { Volume2, VolumeX, Headphones, Trash2, ChevronDown, ChevronRight, UnfoldHorizontal, Upload, Mic, Gauge, Circle } from 'lucide-react';
+import { Volume2, VolumeX, Headphones, Trash2, ChevronDown, ChevronRight, UnfoldHorizontal, Upload, Mic, Gauge, Circle, Sparkles } from 'lucide-react';
 import type { Track as TrackType } from '@/types/track';
 import { COLLAPSED_TRACK_HEIGHT, MIN_TRACK_HEIGHT, MAX_TRACK_HEIGHT } from '@/types/track';
 import { Button } from '@/components/ui/Button';
@@ -13,6 +13,8 @@ import { CircularKnob } from '@/components/ui/CircularKnob';
 import { AutomationLane } from '@/components/automation/AutomationLane';
 import type { AutomationLane as AutomationLaneType, AutomationPoint as AutomationPointType } from '@/types/automation';
 import { createAutomationPoint } from '@/lib/audio/automation/utils';
+import { EffectDevice } from '@/components/effects/EffectDevice';
+import { EffectBrowser } from '@/components/effects/EffectBrowser';
 
 export interface TrackProps {
   track: TrackType;
@@ -78,6 +80,7 @@ export function Track({
   const inputRef = React.useRef<HTMLInputElement>(null);
   const [isResizing, setIsResizing] = React.useState(false);
   const resizeStartRef = React.useRef({ y: 0, height: 0 });
+  const [effectBrowserOpen, setEffectBrowserOpen] = React.useState(false);
 
   // Selection state
   const [isSelecting, setIsSelecting] = React.useState(false);
@@ -617,6 +620,24 @@ export function Track({
                   >
                     A
                   </button>
+
+                  {/* Effects Toggle */}
+                  <button
+                    onClick={() => {
+                      onUpdateTrack(track.id, {
+                        showEffects: !track.showEffects,
+                      });
+                    }}
+                    className={cn(
+                      'h-6 w-6 rounded flex items-center justify-center transition-all',
+                      track.showEffects
+                        ? 'bg-primary text-primary-foreground shadow-md shadow-primary/30'
+                        : 'bg-card hover:bg-accent text-muted-foreground border border-border/50'
+                    )}
+                    title={track.showEffects ? 'Hide effects' : 'Show effects'}
+                  >
+                    <Sparkles className="h-3 w-3" />
+                  </button>
                 </div>
               </div>
             </div>
@@ -751,6 +772,62 @@ export function Track({
         </div>
       )}
 
+      {/* Per-Track Effects Panel */}
+      {!track.collapsed && track.showEffects && (
+        <div className="bg-background/30 border-t border-border/50 p-3">
+          <div className="flex items-center justify-between mb-2">
+            <span className="text-xs font-medium text-foreground">
+              {track.name} - Effects
+            </span>
+            <Button
+              variant="ghost"
+              size="sm"
+              onClick={() => setEffectBrowserOpen(true)}
+              className="h-7 px-2 text-xs"
+            >
+              <Sparkles className="h-3 w-3 mr-1" />
+              Add Effect
+            </Button>
+          </div>
+
+          {track.effectChain.effects.length === 0 ? (
+            <div className="text-center py-8 text-sm text-muted-foreground">
+              No effects on this track
+            </div>
+          ) : (
+            <div className="flex gap-3 overflow-x-auto custom-scrollbar">
+              {track.effectChain.effects.map((effect) => (
+                <EffectDevice
+                  key={effect.id}
+                  effect={effect}
+                  onToggleEnabled={() => onToggleEffect?.(effect.id)}
+                  onRemove={() => onRemoveEffect?.(effect.id)}
+                  onUpdateParameters={(params) => onUpdateEffect?.(effect.id, params)}
+                  onToggleExpanded={() => {
+                    const updatedEffects = track.effectChain.effects.map((e) =>
+                      e.id === effect.id ? { ...e, expanded: !e.expanded } : e
+                    );
+                    onUpdateTrack(track.id, {
+                      effectChain: { ...track.effectChain, effects: updatedEffects },
+                    });
+                  }}
+                />
+              ))}
+            </div>
+          )}
+
+          {/* Effect Browser Dialog */}
+          <EffectBrowser
+            open={effectBrowserOpen}
+            onClose={() => setEffectBrowserOpen(false)}
+            onSelectEffect={(effectType) => {
+              onAddEffect?.(effectType);
+              setEffectBrowserOpen(false);
+            }}
+          />
+        </div>
+      )}
+
       {/* Track Height Resize Handle */}
       {!track.collapsed && (
         <div

lib/audio/track-utils.ts

@@ -59,6 +59,7 @@ export function createTrack(name?: string, color?: TrackColor): Track {
     },
     collapsed: false,
     selected: false,
+    showEffects: false,
     selection: null,
   };
 }

lib/hooks/useMultiTrack.ts

@@ -35,6 +35,7 @@ export function useMultiTrack() {
           effectChain: t.effectChain || createEffectChain(`${t.name} Effects`), // Restore effect chain or create new
           automation: t.automation || { lanes: [], showAutomation: false }, // Restore automation or create new
           selection: t.selection || null, // Initialize selection
+          showEffects: t.showEffects || false, // Restore showEffects state
         }));
       }
     } catch (error) {
@@ -64,6 +65,7 @@ export function useMultiTrack() {
         recordEnabled: track.recordEnabled,
         collapsed: track.collapsed,
         selected: track.selected,
+        showEffects: track.showEffects, // Save effects panel state
         effectChain: track.effectChain, // Save effect chain
         automation: track.automation, // Save automation data
       }));

types/track.ts

@@ -32,6 +32,7 @@ export interface Track {
   // UI state
   collapsed: boolean;
   selected: boolean;
+  showEffects: boolean; // Show/hide per-track effects panel
 
   // Selection (for editing operations)
   selection: Selection | null;