feat: add initial application structure with configuration, UI components, and state management

composables/useConcentration.ts

@@ -0,0 +1,59 @@
+/**
+ * Returns Top source % and HHI-based traffic light (HHI hidden from UI)
+ * Uses Herfindahl-Hirschman Index internally but only exposes traffic light color
+ */
+export const useConcentration = () => {
+  const calculateTopSourcePct = (revenueShares: number[]): number => {
+    if (revenueShares.length === 0) return 0
+    return Math.max(...revenueShares)
+  }
+  
+  const calculateHHI = (revenueShares: number[]): number => {
+    // HHI = sum of squared market shares (as percentages)
+    return revenueShares.reduce((sum, share) => sum + (share * share), 0)
+  }
+  
+  const getConcentrationStatus = (topSourcePct: number, hhi: number): 'green' | 'yellow' | 'red' => {
+    // Primary threshold based on top source %
+    if (topSourcePct > 50) return 'red'
+    if (topSourcePct > 35) return 'yellow'
+    
+    // Secondary check using HHI for more nuanced analysis
+    if (hhi > 2500) return 'red'  // Highly concentrated
+    if (hhi > 1500) return 'yellow'  // Moderately concentrated
+    
+    return 'green'
+  }
+  
+  const getConcentrationMessage = (status: 'green' | 'yellow' | 'red'): string => {
+    switch (status) {
+      case 'red':
+        return 'Most of your money comes from one place. Add another stream to reduce risk.'
+      case 'yellow':
+        return 'Revenue somewhat concentrated. Consider diversifying further.'
+      case 'green':
+        return 'Good revenue diversification.'
+    }
+  }
+  
+  const analyzeConcentration = (revenueStreams: Array<{ targetPct: number }>) => {
+    const shares = revenueStreams.map(stream => stream.targetPct || 0)
+    const topSourcePct = calculateTopSourcePct(shares)
+    const hhi = calculateHHI(shares)
+    const status = getConcentrationStatus(topSourcePct, hhi)
+    
+    return {
+      topSourcePct,
+      status,
+      message: getConcentrationMessage(status)
+      // Note: HHI is deliberately not exposed in return
+    }
+  }
+  
+  return {
+    calculateTopSourcePct,
+    getConcentrationStatus,
+    getConcentrationMessage,
+    analyzeConcentration
+  }
+}