feat(v2): add context fingerprint hash that ignores time-only fields

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

logic/hash.js

@@ -0,0 +1,28 @@
+function stableStringify(value) {
+  if (value === null || typeof value !== 'object') return JSON.stringify(value);
+  if (Array.isArray(value)) return `[${value.map(stableStringify).join(',')}]`;
+  const keys = Object.keys(value).sort();
+  return `{${keys.map((k) => `${JSON.stringify(k)}:${stableStringify(value[k])}`).join(',')}}`;
+}
+
+function djb2Hash(str) {
+  let hash = 5381;
+  for (let i = 0; i < str.length; i += 1) {
+    hash = ((hash << 5) + hash + str.charCodeAt(i)) >>> 0;
+  }
+  return hash.toString(16).padStart(8, '0');
+}
+
+const FINGERPRINT_FIELDS = ['status', 'tecnico_atribuido', 'categoria', 'entidade'];
+
+function buildContextFingerprint(ticket) {
+  const followups = (ticket.followups || []).map((f) => `${f.id}:${f.date}`).sort();
+  const tasks = (ticket.tasks || []).map((t) => `${t.id}:${t.status}:${t.date}`).sort();
+  const picked = {};
+  for (const field of FINGERPRINT_FIELDS) picked[field] = ticket[field];
+  picked.followups = followups;
+  picked.tasks = tasks;
+  return djb2Hash(stableStringify(picked));
+}
+
+module.exports = { stableStringify, djb2Hash, buildContextFingerprint };