diff --git a/src/core/__tests__/dispatch-series.test.ts b/src/core/__tests__/dispatch-series.test.ts
new file mode 100644
index 00000000..fa71028d
--- /dev/null
+++ b/src/core/__tests__/dispatch-series.test.ts
@@ -0,0 +1,194 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import {
+  requireIntInRange,
+  clampIosSwipeDuration,
+  shouldUseIosTapSeries,
+  shouldUseIosDragSeries,
+  computeDeterministicJitter,
+  runRepeatedSeries,
+} from '../dispatch-series.ts';
+import { AppError } from '../../utils/errors.ts';
+import type { DeviceInfo } from '../../utils/device.ts';
+
+const iosDevice: DeviceInfo = { platform: 'ios', id: 'test', name: 'iPhone', kind: 'simulator' };
+const androidDevice: DeviceInfo = {
+  platform: 'android',
+  id: 'test',
+  name: 'Pixel',
+  kind: 'emulator',
+};
+
+// --- requireIntInRange ---
+
+test('requireIntInRange returns value at lower bound', () => {
+  assert.equal(requireIntInRange(0, 'x', 0, 10), 0);
+});
+
+test('requireIntInRange returns value at upper bound', () => {
+  assert.equal(requireIntInRange(10, 'x', 0, 10), 10);
+});
+
+test('requireIntInRange returns value within range', () => {
+  assert.equal(requireIntInRange(5, 'x', 0, 10), 5);
+});
+
+test('requireIntInRange throws for value below minimum', () => {
+  assert.throws(
+    () => requireIntInRange(-1, 'x', 0, 10),
+    (e: unknown) => e instanceof AppError && e.code === 'INVALID_ARGS',
+  );
+});
+
+test('requireIntInRange throws for value above maximum', () => {
+  assert.throws(
+    () => requireIntInRange(11, 'x', 0, 10),
+    (e: unknown) => e instanceof AppError && e.code === 'INVALID_ARGS',
+  );
+});
+
+test('requireIntInRange throws for non-integer value', () => {
+  assert.throws(
+    () => requireIntInRange(5.5, 'x', 0, 10),
+    (e: unknown) => e instanceof AppError && e.code === 'INVALID_ARGS',
+  );
+});
+
+test('requireIntInRange throws for non-finite values', () => {
+  for (const value of [NaN, Infinity, -Infinity]) {
+    assert.throws(
+      () => requireIntInRange(value, 'x', 0, 10),
+      (e: unknown) => e instanceof AppError && e.code === 'INVALID_ARGS',
+    );
+  }
+});
+
+// --- clampIosSwipeDuration ---
+
+test('clampIosSwipeDuration returns value within bounds unchanged', () => {
+  assert.equal(clampIosSwipeDuration(30), 30);
+});
+
+test('clampIosSwipeDuration clamps below-minimum to 16', () => {
+  assert.equal(clampIosSwipeDuration(5), 16);
+});
+
+test('clampIosSwipeDuration clamps above-maximum to 60', () => {
+  assert.equal(clampIosSwipeDuration(100), 60);
+});
+
+test('clampIosSwipeDuration returns exact boundary values unchanged', () => {
+  assert.equal(clampIosSwipeDuration(16), 16);
+  assert.equal(clampIosSwipeDuration(60), 60);
+});
+
+test('clampIosSwipeDuration rounds fractional input before clamping', () => {
+  assert.equal(clampIosSwipeDuration(30.4), 30);
+  assert.equal(clampIosSwipeDuration(15.6), 16);
+});
+
+// --- shouldUseIosTapSeries ---
+
+test('shouldUseIosTapSeries returns true for iOS with count > 1 and no hold or jitter', () => {
+  assert.equal(shouldUseIosTapSeries(iosDevice, 2, 0, 0), true);
+});
+
+test('shouldUseIosTapSeries returns false for Android', () => {
+  assert.equal(shouldUseIosTapSeries(androidDevice, 2, 0, 0), false);
+});
+
+test('shouldUseIosTapSeries returns false when count is 1', () => {
+  assert.equal(shouldUseIosTapSeries(iosDevice, 1, 0, 0), false);
+});
+
+test('shouldUseIosTapSeries returns false when holdMs is non-zero', () => {
+  assert.equal(shouldUseIosTapSeries(iosDevice, 2, 100, 0), false);
+});
+
+test('shouldUseIosTapSeries returns false when jitterPx is non-zero', () => {
+  assert.equal(shouldUseIosTapSeries(iosDevice, 2, 0, 5), false);
+});
+
+// --- shouldUseIosDragSeries ---
+
+test('shouldUseIosDragSeries returns true for iOS with count > 1', () => {
+  assert.equal(shouldUseIosDragSeries(iosDevice, 2), true);
+});
+
+test('shouldUseIosDragSeries returns false for Android', () => {
+  assert.equal(shouldUseIosDragSeries(androidDevice, 2), false);
+});
+
+test('shouldUseIosDragSeries returns false when count is 1', () => {
+  assert.equal(shouldUseIosDragSeries(iosDevice, 1), false);
+});
+
+// --- computeDeterministicJitter ---
+
+test('computeDeterministicJitter scales pattern entry by jitter pixels', () => {
+  assert.deepEqual(computeDeterministicJitter(1, 3), [3, 0]);
+});
+
+test('computeDeterministicJitter returns [0, 0] at index 0', () => {
+  assert.deepEqual(computeDeterministicJitter(0, 5), [0, 0]);
+});
+
+test('computeDeterministicJitter cycles through 9-entry pattern', () => {
+  assert.deepEqual(computeDeterministicJitter(9, 2), [0, 0]);
+});
+
+test('computeDeterministicJitter returns [0, 0] when jitterPx is 0', () => {
+  assert.deepEqual(computeDeterministicJitter(1, 0), [0, 0]);
+});
+
+test('computeDeterministicJitter returns [0, 0] when jitterPx is negative', () => {
+  assert.deepEqual(computeDeterministicJitter(1, -3), [0, 0]);
+});
+
+// --- runRepeatedSeries ---
+
+test('runRepeatedSeries invokes operation for each index in order', async () => {
+  const indices: number[] = [];
+  await runRepeatedSeries(4, 0, async (i) => {
+    indices.push(i);
+  });
+  assert.deepEqual(indices, [0, 1, 2, 3]);
+});
+
+test('runRepeatedSeries does not invoke operation when count is 0', async () => {
+  const indices: number[] = [];
+  await runRepeatedSeries(0, 0, async (i) => {
+    indices.push(i);
+  });
+  assert.deepEqual(indices, []);
+});
+
+test('runRepeatedSeries pauses between operations but not after the last', async (t) => {
+  const timeoutDelays: number[] = [];
+  t.mock.method(globalThis, 'setTimeout', (cb: () => void, ms: number) => {
+    timeoutDelays.push(ms);
+    cb();
+    return 0;
+  });
+  const pauseMs = 50;
+  const calls: number[] = [];
+  await runRepeatedSeries(3, pauseMs, async (i) => {
+    calls.push(i);
+  });
+  assert.deepEqual(calls, [0, 1, 2]);
+  // 3 operations with pauses only between them = 2 pauses
+  assert.deepEqual(timeoutDelays, [pauseMs, pauseMs]);
+});
+
+test('runRepeatedSeries propagates operation error and stops iteration', async () => {
+  const indices: number[] = [];
+  await assert.rejects(
+    () =>
+      runRepeatedSeries(5, 0, async (i) => {
+        indices.push(i);
+        if (i === 2) throw new Error('boom');
+      }),
+    (e: unknown) => e instanceof Error && e.message === 'boom',
+  );
+  assert.deepEqual(indices, [0, 1, 2]);
+});