[Feature] Add suggestions engine for common errors

[yellow-seed]

Transaction Debugger - 提案エンジン実装

概要

トランザクション失敗原因に基づいて、解決方法を提案する

実装内容

# lib/transaction_debugger/suggestions_engine.rb
module TransactionDebugger
  class SuggestionsEngine
    def generate(transaction, receipt, revert_reason)
      suggestions = []
      
      # Analyze revert reason
      suggestions += analyze_revert_reason(revert_reason) if revert_reason
      
      # Analyze gas
      suggestions += analyze_gas(transaction, receipt)
      
      # Analyze nonce
      suggestions += analyze_nonce(transaction)
      
      suggestions
    end
    
    private
    
    def analyze_revert_reason(reason)
      suggestions = []
      
      case reason
      when /insufficient balance/i
        suggestions << {
          title: "Insufficient Balance",
          description: "The sender doesn't have enough ETH",
          actions: [
            "Check balance: eth.getBalance(address)",
            "Send more ETH to the address",
            "Reduce the transfer amount"
          ]
        }
      when /allowance|approved/i
        suggestions << {
          title: "Insufficient Allowance",
          description: "The contract doesn't have permission to spend tokens",
          actions: [
            "Call token.approve(spender, amount)",
            "Check current allowance: token.allowance(owner, spender)",
            "Increase allowance to required amount"
          ]
        }
      when /out of gas/i
        suggestions << {
          title: "Out of Gas",
          description: "Transaction ran out of gas during execution",
          actions: [
            "Increase gas limit (current was likely too low)",
            "Optimize contract code if possible",
            "Break operation into smaller transactions"
          ]
        }
      end
      
      suggestions
    end
    
    def analyze_gas(transaction, receipt)
      suggestions = []
      
      # Check if gas was almost exhausted
      usage = (receipt.gas_used.to_f / transaction.gas * 100)
      
      if usage > 95
        suggestions << {
          title: "High Gas Usage",
          description: "Transaction used #{usage.round(1)}% of gas limit",
          actions: [
            "Increase gas limit to avoid potential failures",
            "Current limit: #{transaction.gas}"
          ]
        }
      end
      
      suggestions
    end
    
    def analyze_nonce(transaction)
      # TODO: Check for nonce issues
      []
    end
  end
end

完了条件

• 主要なエラーパターンに対して提案を生成できる
• 提案にタイトル・説明・アクションが含まれる
• CLIで見やすく表示される
• テストが全てパスする

Phase

Phase 3 - 高度な機能

Dependencies

• Issue [Feature] Improve error message formatting #12: [Feature] Improve error message formatting