Sync previews when clip source changes

Sources/GrowthLapse/ContentView.swift

@@ -603,6 +603,9 @@ private struct ClipPreviewView: View {
             .onChange(of: clip.id) { _ in
                 loadClip()
             }
+            .onChange(of: clip.sourcePath) { _ in
+                loadClip()
+            }
             .onChange(of: clip.segmentStart) { _ in
                 seekToSegmentStart()
             }
@@ -708,6 +711,7 @@ private struct ClipVariantPickerView: View {
 
             if let selectedVariant {
                 VariantPreviewView(variant: selectedVariant)
+                    .id(selectedVariant.sourcePath)
                     .frame(height: 220)
                     .clipShape(RoundedRectangle(cornerRadius: 8))
             }
@@ -745,8 +749,19 @@ private struct ClipVariantPickerView: View {
         }
         .padding()
         .onAppear {
-            selectedVariantID = selectedVariant?.id
+            selectedVariantID = currentVariantID()
         }
+        .onChange(of: clip.id) { _ in
+            selectedVariantID = currentVariantID()
+        }
+        .onChange(of: clip.sourcePath) { _ in
+            selectedVariantID = currentVariantID()
+        }
+    }
+
+    private func currentVariantID() -> UUID? {
+        clip.availableVariants.first(where: { $0.sourcePath == clip.sourcePath })?.id
+            ?? clip.availableVariants.first?.id
     }
 
     private func format(_ value: Double) -> String {
@@ -770,6 +785,9 @@ private struct VariantPreviewView: View {
             .onChange(of: variant.id) { _ in
                 loadVariant()
             }
+            .onChange(of: variant.sourcePath) { _ in
+                loadVariant()
+            }
     }
 
     private func loadVariant() {