#!/usr/bin/env node
// post-session-guard.mjs — Runtime trifecta detection (Rule of Two)
// v5.0: Configurable TRIFECTA_MODE (block|warn|off), long-horizon 100-call window,
// behavioral drift via Jensen-Shannon divergence
import { readFileSync, appendFileSync } from 'node:fs';

const TRIFECTA_MODE = (process.env.LLM_SECURITY_TRIFECTA_MODE || 'warn').toLowerCase();
const SLIDING_WINDOW = 20;
const LONG_HORIZON_WINDOW = 100;

const input = JSON.parse(readFileSync('/dev/stdin', 'utf-8'));
const toolName = input.tool_name || '';

// Classify tool
function classifyTool(name) {
  if (/Read|Glob|Grep/.test(name)) return 'read';
  if (/Write|Edit/.test(name)) return 'write';
  if (/Bash/.test(name)) return 'exec';
  if (/WebFetch|WebSearch/.test(name)) return 'network';
  return 'other';
}

// Jensen-Shannon divergence for behavioral drift detection
function jsDivergence(p, q) {
  const m = p.map((pi, i) => (pi + q[i]) / 2);
  let kl1 = 0, kl2 = 0;
  for (let i = 0; i < p.length; i++) {
    if (p[i] > 0 && m[i] > 0) kl1 += p[i] * Math.log2(p[i] / m[i]);
    if (q[i] > 0 && m[i] > 0) kl2 += q[i] * Math.log2(q[i] / m[i]);
  }
  return (kl1 + kl2) / 2;
}

if (TRIFECTA_MODE === 'off') {
  process.stdout.write(JSON.stringify({ decision: 'allow' }));
  process.exit(0);
}

// Trifecta detection logic would go here (simplified for fixture)
process.stdout.write(JSON.stringify({ decision: 'allow' }));
