Risk Scoring

// packages/preflight/src/risk-scorer.ts (simplified)
export function computeRiskScore(context: RiskContext): RiskResult {
  let score = 0;
  const reasons: string[] = [];

  if (!context.contractInAllowlist)     { score += 40; reasons.push("Contract not in allowlist (+40)"); }
  if (!context.tokenInAllowlist)        { score += 20; reasons.push("Token not in allowlist (+20)"); }
  if (context.slippageBps > 300)        { score += 15; reasons.push(`High slippage ... (+15)`); }
  if (valueWei > maxValueWei / 2n)      { score += 20; reasons.push("Large value relative to limit (+20)"); }
  if (isUnboundedApproval)              { score += 25; reasons.push("Unbounded or very large approval amount (+25)"); }
  if (context.simulationReverted)       { score += 50; reasons.push("Transaction simulation reverted (+50)"); }
  if (context.gasEstimate > 400_000n)   { score += 10; reasons.push(`Abnormal gas estimate: ... (+10)`); }

  return { score: Math.min(score, 100), reasons };
}

// packages/types/src/index.ts
export interface RiskContext {
  contractInAllowlist: boolean;
  tokenInAllowlist: boolean;
  slippageBps: number;
  simulationReverted: boolean;
  gasEstimate: bigint;
  approvalAmount?: bigint;      // set for approve actions
  maxApprovalAmount?: bigint;    // from PolicyConfig
  valueWei?: bigint;             // set for transfers and swaps
  maxValueWei?: bigint;          // from PolicyConfig
}

TxIntent
  |
  v
PreflightService.simulate(intent, buildPlan)
  |-- 1. eth_call simulation (reverted?)
  |-- 2. eth_estimateGas
  |-- 3. collectBalanceDiffs
  |-- 4. collectAllowanceChanges
  |-- 5. buildRiskContext(intent, simulationSuccess, gasEstimate)
  |-- 6. computeRiskScore(riskContext) --> { score, reasons }
  |
  v
PreflightResult { riskScore, riskReasons, warnings, ... }
  |
  v
PolicyEngine.evaluate(intent, config, { riskScore })
  |-- Check 7 of 8: if riskScore > config.maxRiskScore
  |       --> decision = "require_approval"
  |
  v
PolicyDecision { decision: "allow" | "require_approval" | "deny" }