diff --git a/logic/hash.js b/logic/hash.js
new file mode 100644
index 0000000..6ab40d2
--- /dev/null
+++ b/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 };
diff --git a/logic/hash.test.js b/logic/hash.test.js
new file mode 100644
index 0000000..b2a084b
--- /dev/null
+++ b/logic/hash.test.js
@@ -0,0 +1,38 @@
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const { buildContextFingerprint, stableStringify } = require('./hash');
+
+function baseTicket(overrides) {
+  return Object.assign({
+    status: 2,
+    tecnico_atribuido: 'Wagner',
+    categoria: 'Rede',
+    entidade: 'Matriz',
+    followups: [{ id: 1, date: '2026-08-20 10:00:00' }],
+    tasks: [{ id: 1, status: 1, date: '2026-08-19 09:00:00' }],
+    dias_aberto: 10,
+    dias_sem_interacao: 3,
+  }, overrides);
+}
+
+test('alterar apenas dias_aberto/dias_sem_interacao NAO muda o hash', () => {
+  const a = buildContextFingerprint(baseTicket({ dias_aberto: 10, dias_sem_interacao: 3 }));
+  const b = buildContextFingerprint(baseTicket({ dias_aberto: 11, dias_sem_interacao: 4 }));
+  assert.equal(a, b);
+});
+
+test('novo followup MUDA o hash', () => {
+  const a = buildContextFingerprint(baseTicket({}));
+  const b = buildContextFingerprint(baseTicket({ followups: [{ id: 1, date: '2026-08-20 10:00:00' }, { id: 2, date: '2026-08-21 08:00:00' }] }));
+  assert.notEqual(a, b);
+});
+
+test('mudanca de tecnico MUDA o hash', () => {
+  const a = buildContextFingerprint(baseTicket({ tecnico_atribuido: 'Wagner' }));
+  const b = buildContextFingerprint(baseTicket({ tecnico_atribuido: 'Eric' }));
+  assert.notEqual(a, b);
+});
+
+test('stableStringify ignora ordem de chaves', () => {
+  assert.equal(stableStringify({ b: 1, a: 2 }), stableStringify({ a: 2, b: 1 }));
+});