diff --git a/logic/diversity.js b/logic/diversity.js
new file mode 100644
index 0000000..7d209b5
--- /dev/null
+++ b/logic/diversity.js
@@ -0,0 +1,34 @@
+function selectTop(scored, topN, config) {
+  const eligible = scored.filter((item) => !item.excludedFromTop10);
+  const excluded = scored.filter((item) => item.excludedFromTop10);
+
+  const sorted = [...eligible].sort((a, b) => b.score - a.score);
+
+  const groupCap = Math.max(1, Math.ceil(topN * 0.5));
+  const groupCounts = {};
+  const firstPass = [];
+  const deferred = [];
+
+  for (const item of sorted) {
+    const count = groupCounts[item.group] || 0;
+    if (count < groupCap && firstPass.length < topN) {
+      firstPass.push(item);
+      groupCounts[item.group] = count + 1;
+    } else {
+      deferred.push(item);
+    }
+  }
+
+  let selected = firstPass;
+  if (selected.length < topN) {
+    selected = selected.concat(deferred.slice(0, topN - selected.length));
+  }
+  selected = selected.slice(0, topN);
+
+  const selectedIds = new Set(selected.map((item) => item.ticket.id));
+  const notSelected = sorted.filter((item) => !selectedIds.has(item.ticket.id));
+
+  return { selected, excluded: excluded.concat(notSelected) };
+}
+
+module.exports = { selectTop };
diff --git a/logic/diversity.test.js b/logic/diversity.test.js
new file mode 100644
index 0000000..635f132
--- /dev/null
+++ b/logic/diversity.test.js
@@ -0,0 +1,37 @@
+const { test } = require('node:test');
+const assert = require('node:assert/strict');
+const { selectTop } = require('./diversity');
+
+function item(id, score, group, excludedFromTop10) {
+  return { ticket: { id }, score, group, excludedFromTop10: Boolean(excludedFromTop10), aiClassification: {} };
+}
+
+test('Top final nunca ultrapassa topN', () => {
+  const scored = Array.from({ length: 20 }, (_, i) => item(i, 100 - i, 'ranking_geral', false));
+  const { selected } = selectTop(scored, 10, {});
+  assert.equal(selected.length, 10);
+});
+
+test('itens excluidos do Top10 nunca aparecem selecionados', () => {
+  const scored = [item(1, 500, 'critico_acionavel', true), item(2, 10, 'ranking_geral', false)];
+  const { selected } = selectTop(scored, 10, {});
+  assert.ok(!selected.some((s) => s.ticket.id === 1));
+});
+
+test('10 criticos legitimos no mesmo grupo entram todos (diversidade nao bloqueia emergencia real)', () => {
+  const scored = Array.from({ length: 10 }, (_, i) => item(i, 500 - i, 'critico_acionavel', false));
+  const { selected } = selectTop(scored, 10, {});
+  assert.equal(selected.length, 10);
+  assert.deepEqual(selected.map((s) => s.ticket.id).sort(), scored.map((s) => s.ticket.id).sort());
+});
+
+test('com grupos variados, ordena por score respeitando diversidade leve', () => {
+  const scored = [
+    ...Array.from({ length: 8 }, (_, i) => item(`c${i}`, 300 - i, 'critico_acionavel', false)),
+    item('t1', 250, 'sem_tecnico', false),
+    item('t2', 240, 'quick_win', false),
+  ];
+  const { selected } = selectTop(scored, 10, {});
+  assert.equal(selected.length, 10);
+  assert.ok(selected.some((s) => s.ticket.id === 't1'));
+});