diff --git a/tests/pirate-ai.test.mjs b/tests/pirate-ai.test.mjs
new file mode 100644
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+++ b/tests/pirate-ai.test.mjs
@@ -0,0 +1,29 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+
+import { PIRATE_CLASSES, pirateClassForWave, separationVector } from '../src/pirate-ai.js';
+
+test('pirate classes expose distinct combat roles', () => {
+  assert.ok(PIRATE_CLASSES.raider.speed > PIRATE_CLASSES.frigate.speed);
+  assert.ok(PIRATE_CLASSES.raider.hull < PIRATE_CLASSES.frigate.hull);
+  assert.ok(PIRATE_CLASSES.captain.hull > PIRATE_CLASSES.frigate.hull);
+  assert.ok(PIRATE_CLASSES.captain.damage > PIRATE_CLASSES.frigate.damage);
+});
+
+test('waves introduce raiders and captains without exceeding the wave composition', () => {
+  assert.equal(pirateClassForWave(1, 0, 1).key, 'frigate');
+  assert.equal(pirateClassForWave(3, 0, 3).key, 'raider');
+  assert.equal(pirateClassForWave(4, 3, 4).key, 'captain');
+});
+
+test('separation steering pushes nearby ships apart and ignores distant ships', () => {
+  const ship = { x: 100, y: 100, active: true };
+  const close = { x: 150, y: 100, active: true };
+  const far = { x: 500, y: 100, active: true };
+
+  const vector = separationVector(ship, [ship, close, far], 125);
+
+  assert.ok(vector.x < 0, 'ship should steer away from a close ship on its right');
+  assert.equal(vector.y, 0);
+  assert.ok(Math.hypot(vector.x, vector.y) <= 1);
+});