Fix compilation errors in ChartsViewModel and AllocationEvolutionChart

- Remove unnecessary optional binding for non-optional source.id
- Break up AllocationEvolutionChart body to help Swift type-checker

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

PortfolioJournal/ViewModels/ChartsViewModel.swift

@@ -294,8 +294,7 @@ class ChartsViewModel: ObservableObject {
         let sources: [InvestmentSource]
         if !selectedSourceIds.isEmpty {
             sources = sourceRepository.sources.filter { source in
-                guard let id = source.id else { return false }
-                return selectedSourceIds.contains(id) && shouldIncludeSource(source)
+                selectedSourceIds.contains(source.id) && shouldIncludeSource(source)
             }
         } else if let selectedSource {
             sources = sourceRepository.sources.filter { $0.id == selectedSource.id && shouldIncludeSource($0) }

PortfolioJournal/Views/Charts/ChartsContainerView.swift

@@ -929,46 +929,38 @@ struct CashflowStackedChartView: View {
 
 // MARK: - Allocation Evolution Chart
 
+struct AllocationEvolutionDataPoint: Identifiable {
+    let id: String
+    let date: Date
+    let category: String
+    let percentage: Double
+    let color: String
+}
+
 struct AllocationEvolutionChart: View {
     let data: [(date: Date, category: String, percentage: Double, color: String)]
 
+    private var identifiableData: [AllocationEvolutionDataPoint] {
+        data.enumerated().map { index, item in
+            AllocationEvolutionDataPoint(
+                id: "\(index)-\(item.category)",
+                date: item.date,
+                category: item.category,
+                percentage: item.percentage,
+                color: item.color
+            )
+        }
+    }
+
     var body: some View {
         VStack(alignment: .leading, spacing: 12) {
             Text("Allocation Over Time")
                 .font(.headline)
 
             if data.isEmpty {
-                Text("Not enough data to show allocation evolution.")
-                    .foregroundColor(.secondary)
-                    .frame(height: 260)
+                emptyView
             } else {
-                Chart {
-                    ForEach(data, id: \.date.description + \.category) { item in
-                        AreaMark(
-                            x: .value("Date", item.date),
-                            y: .value("Percentage", item.percentage)
-                        )
-                        .foregroundStyle(by: .value("Category", item.category))
-                    }
-                }
-                .chartForegroundStyleScale(domain: categoryNames, range: categoryColors)
-                .chartXAxis {
-                    AxisMarks(values: .stride(by: .month, count: 2)) { _ in
-                        AxisValueLabel(format: .dateTime.month(.abbreviated).year(.twoDigits))
-                    }
-                }
-                .chartYAxis {
-                    AxisMarks(position: .leading) { value in
-                        AxisValueLabel {
-                            if let pct = value.as(Double.self) {
-                                Text(String(format: "%.0f%%", pct))
-                                    .font(.caption)
-                            }
-                        }
-                    }
-                }
-                .frame(height: 260)
-                .drawingGroup()
+                chartView
             }
         }
         .padding()
@@ -977,6 +969,40 @@ struct AllocationEvolutionChart: View {
         .shadow(color: .black.opacity(0.05), radius: 8, y: 2)
     }
 
+    private var emptyView: some View {
+        Text("Not enough data to show allocation evolution.")
+            .foregroundColor(.secondary)
+            .frame(height: 260)
+    }
+
+    private var chartView: some View {
+        Chart(identifiableData) { item in
+            AreaMark(
+                x: .value("Date", item.date),
+                y: .value("Percentage", item.percentage)
+            )
+            .foregroundStyle(by: .value("Category", item.category))
+        }
+        .chartForegroundStyleScale(domain: categoryNames, range: categoryColors)
+        .chartXAxis {
+            AxisMarks(values: .stride(by: .month, count: 2)) { _ in
+                AxisValueLabel(format: .dateTime.month(.abbreviated).year(.twoDigits))
+            }
+        }
+        .chartYAxis {
+            AxisMarks(position: .leading) { value in
+                AxisValueLabel {
+                    if let pct = value.as(Double.self) {
+                        Text(String(format: "%.0f%%", pct))
+                            .font(.caption)
+                    }
+                }
+            }
+        }
+        .frame(height: 260)
+        .drawingGroup()
+    }
+
     private var categoryNames: [String] {
         Array(Set(data.map { $0.category })).sorted()
     }