scripts/freshness-gate.mjs

import fs from 'node:fs';
import crypto from 'node:crypto';

const input = process.argv[2];
if (!input) {
  console.error('usage: node freshness-gate.mjs <trace.jsonl>');
  process.exit(2);
}

const raw = fs.readFileSync(input, 'utf8');
const lines = raw.split(/\r?\n/).filter(line => line.trim().length > 0);
let previousSeq = -1;
let lastMutation = null;
let lastVerification = null;
let verificationPending = true;
let hasVerification = false;
let latestClaim = null;

const currentReason = () => !hasVerification
  ? 'VERIFICATION_MISSING'
  : verificationPending ? 'VERIFICATION_STALE' : 'VERIFICATION_FRESH';

for (const line of lines) {
  const event = JSON.parse(line);
  if (!Number.isInteger(event.seq) || event.seq <= previousSeq) {
    throw new Error('trace seq must be strictly increasing integers');
  }
  previousSeq = event.seq;
  if (event.type === 'mutation' && event.success === true) {
    lastMutation = event.seq;
    verificationPending = true;
  } else if (event.type === 'verification' && event.success === true) {
    lastVerification = event.seq;
    hasVerification = true;
    verificationPending = false;
  } else if (event.type === 'completion_claim') {
    latestClaim = {
      seq: event.seq,
      allowed: hasVerification && !verificationPending,
      reason: currentReason()
    };
  }
}

const receipt = {
  schema: 'comptext-evidence-freshness/v1',
  trace_digest: `sha256:${crypto.createHash('sha256').update(raw).digest('hex')}`,
  event_count: lines.length,
  last_successful_mutation_seq: lastMutation,
  last_successful_verification_seq: lastVerification,
  verification_pending: verificationPending,
  next_completion_allowed: hasVerification && !verificationPending,
  reason: currentReason(),
  latest_completion_claim: latestClaim
};

process.stdout.write(`${JSON.stringify(receipt)}\n`);