Add PDF translation API, utilities, docs, and config

Introduces core backend and frontend infrastructure for a PDF translation interface. Adds API endpoints for translation, PDF testing, and AI provider testing; implements PDF text extraction, cost tracking, and pricing logic in the lib directory; adds reusable UI components; and provides comprehensive documentation (SDD, environment setup, Claude instructions). Updates Tailwind and global styles, and includes a sample test PDF and configuration files.

lib/cost-tracker.ts

@@ -0,0 +1,229 @@
+// Cost accumulation and tracking system
+interface CostSession {
+  id: string
+  timestamp: number
+  model: string
+  provider: string
+  tokenUsage: {
+    promptTokens: number
+    completionTokens: number
+    totalTokens: number
+  }
+  cost: {
+    inputCost: number
+    outputCost: number
+    totalCost: number
+    currency: string
+  }
+}
+
+interface CostSummary {
+  totalSessions: number
+  totalTokens: number
+  totalCost: number
+  currency: string
+  startDate: number
+  lastUpdated: number
+  byProvider: Record<string, {
+    sessions: number
+    tokens: number
+    cost: number
+  }>
+  byModel: Record<string, {
+    sessions: number
+    tokens: number
+    cost: number
+  }>
+}
+
+class CostTracker {
+  private readonly STORAGE_KEY = 'pdf_translation_cost_tracker'
+
+  // Get stored cost summary
+  getCostSummary(): CostSummary {
+    if (typeof window === 'undefined') {
+      // Server-side fallback
+      return this.getDefaultSummary()
+    }
+
+    try {
+      const stored = localStorage.getItem(this.STORAGE_KEY)
+      if (!stored) {
+        return this.getDefaultSummary()
+      }
+      return JSON.parse(stored)
+    } catch (error) {
+      console.error('Error reading cost summary:', error)
+      return this.getDefaultSummary()
+    }
+  }
+
+  // Add new cost session
+  addCostSession(session: Omit<CostSession, 'id' | 'timestamp'>): CostSummary {
+    if (typeof window === 'undefined') {
+      // Server-side fallback
+      return this.getDefaultSummary()
+    }
+
+    const summary = this.getCostSummary()
+    const now = Date.now()
+    
+    const newSession: CostSession = {
+      ...session,
+      id: `session_${now}_${Math.random().toString(36).substr(2, 9)}`,
+      timestamp: now
+    }
+
+    // Update summary
+    summary.totalSessions += 1
+    summary.totalTokens += session.tokenUsage.totalTokens
+    summary.totalCost += session.cost.totalCost
+    summary.lastUpdated = now
+    
+    if (summary.startDate === 0) {
+      summary.startDate = now
+    }
+
+    // Update by provider
+    if (!summary.byProvider[session.provider]) {
+      summary.byProvider[session.provider] = { sessions: 0, tokens: 0, cost: 0 }
+    }
+    summary.byProvider[session.provider].sessions += 1
+    summary.byProvider[session.provider].tokens += session.tokenUsage.totalTokens
+    summary.byProvider[session.provider].cost += session.cost.totalCost
+
+    // Update by model
+    if (!summary.byModel[session.model]) {
+      summary.byModel[session.model] = { sessions: 0, tokens: 0, cost: 0 }
+    }
+    summary.byModel[session.model].sessions += 1
+    summary.byModel[session.model].tokens += session.tokenUsage.totalTokens
+    summary.byModel[session.model].cost += session.cost.totalCost
+
+    // Save to localStorage
+    try {
+      localStorage.setItem(this.STORAGE_KEY, JSON.stringify(summary))
+    } catch (error) {
+      console.error('Error saving cost summary:', error)
+    }
+
+    return summary
+  }
+
+  // Reset cost tracking
+  resetCostTracking(): CostSummary {
+    if (typeof window === 'undefined') {
+      return this.getDefaultSummary()
+    }
+
+    const summary = this.getDefaultSummary()
+    try {
+      localStorage.setItem(this.STORAGE_KEY, JSON.stringify(summary))
+    } catch (error) {
+      console.error('Error resetting cost tracking:', error)
+    }
+    return summary
+  }
+
+  // Export cost data
+  exportCostData(): string {
+    const summary = this.getCostSummary()
+    return JSON.stringify(summary, null, 2)
+  }
+
+  // Format cost for display
+  formatCost(amount: number, currency: string = 'USD'): string {
+    return new Intl.NumberFormat('en-US', {
+      style: 'currency',
+      currency: currency,
+      minimumFractionDigits: 4,
+      maximumFractionDigits: 4
+    }).format(amount)
+  }
+
+  // Format large numbers
+  formatNumber(num: number): string {
+    if (num >= 1000000) {
+      return (num / 1000000).toFixed(1) + 'M'
+    } else if (num >= 1000) {
+      return (num / 1000).toFixed(1) + 'K'
+    }
+    return num.toString()
+  }
+
+  // Get cost insights
+  getCostInsights(): {
+    averageCostPerSession: number
+    averageTokensPerSession: number
+    mostUsedProvider: string
+    mostUsedModel: string
+    dailyAverage: number
+  } {
+    const summary = this.getCostSummary()
+    
+    if (summary.totalSessions === 0) {
+      return {
+        averageCostPerSession: 0,
+        averageTokensPerSession: 0,
+        mostUsedProvider: '',
+        mostUsedModel: '',
+        dailyAverage: 0
+      }
+    }
+
+    // Calculate averages
+    const averageCostPerSession = summary.totalCost / summary.totalSessions
+    const averageTokensPerSession = summary.totalTokens / summary.totalSessions
+    
+    // Find most used provider
+    let mostUsedProvider = ''
+    let maxProviderSessions = 0
+    Object.entries(summary.byProvider).forEach(([provider, stats]) => {
+      if (stats.sessions > maxProviderSessions) {
+        maxProviderSessions = stats.sessions
+        mostUsedProvider = provider
+      }
+    })
+
+    // Find most used model
+    let mostUsedModel = ''
+    let maxModelSessions = 0
+    Object.entries(summary.byModel).forEach(([model, stats]) => {
+      if (stats.sessions > maxModelSessions) {
+        maxModelSessions = stats.sessions
+        mostUsedModel = model
+      }
+    })
+
+    // Calculate daily average
+    const daysSinceStart = summary.startDate > 0 
+      ? Math.max(1, Math.ceil((Date.now() - summary.startDate) / (24 * 60 * 60 * 1000)))
+      : 1
+    const dailyAverage = summary.totalCost / daysSinceStart
+
+    return {
+      averageCostPerSession,
+      averageTokensPerSession,
+      mostUsedProvider,
+      mostUsedModel,
+      dailyAverage
+    }
+  }
+
+  private getDefaultSummary(): CostSummary {
+    return {
+      totalSessions: 0,
+      totalTokens: 0,
+      totalCost: 0,
+      currency: 'USD',
+      startDate: 0,
+      lastUpdated: 0,
+      byProvider: {},
+      byModel: {}
+    }
+  }
+}
+
+// Export singleton instance
+export const costTracker = new CostTracker()
+export type { CostSession, CostSummary }