diff --git a/packages/cli/src/commands/iterate-options.ts b/packages/cli/src/commands/iterate-options.ts
new file mode 100644
index 00000000..200575b4
--- /dev/null
+++ b/packages/cli/src/commands/iterate-options.ts
@@ -0,0 +1,22 @@
+import { InvalidArgumentError } from 'commander';
+
+export function parsePositiveSafeInteger(value: string): number {
+  const parsed = Number(value);
+  if (!Number.isSafeInteger(parsed) || parsed < 1) {
+    throw new InvalidArgumentError('must be a positive safe integer');
+  }
+  return parsed;
+}
+
+export function parseQuietHours(value: string): string {
+  const match = value.match(/^(\d{1,2})-(\d{1,2})$/);
+  if (!match) {
+    throw new InvalidArgumentError('must use start-end format, for example 22-08');
+  }
+  const start = Number(match[1]);
+  const end = Number(match[2]);
+  if (start > 23 || end > 23) {
+    throw new InvalidArgumentError('hours must be between 0 and 23');
+  }
+  return value;
+}
diff --git a/packages/cli/src/commands/iterate.test.ts b/packages/cli/src/commands/iterate.test.ts
new file mode 100644
index 00000000..4892cab6
--- /dev/null
+++ b/packages/cli/src/commands/iterate.test.ts
@@ -0,0 +1,32 @@
+import { describe, expect, it } from 'vitest';
+import { parsePositiveSafeInteger, parseQuietHours } from './iterate-options.js';
+
+describe('parsePositiveSafeInteger', () => {
+  it('accepts positive safe integer intervals', () => {
+    expect(parsePositiveSafeInteger('60')).toBe(60);
+  });
+
+  it.each(['nope', '0', '-1', '1.5', 'Infinity', '9007199254740992'])(
+    'rejects invalid interval %s',
+    (value) => {
+      expect(() => parsePositiveSafeInteger(value)).toThrow('positive safe integer');
+    },
+  );
+});
+
+describe('parseQuietHours', () => {
+  it.each(['22-08', '0-23', '09-17'])('accepts valid local hour range %s', (value) => {
+    expect(parseQuietHours(value)).toBe(value);
+  });
+
+  it.each(['abc', '22', '22:08', '22-8-1', '-1-08'])(
+    'rejects invalid quiet-hours format %s',
+    (value) => {
+      expect(() => parseQuietHours(value)).toThrow('start-end format');
+    },
+  );
+
+  it.each(['24-08', '22-24', '23-99'])('rejects out-of-range quiet hours %s', (value) => {
+    expect(() => parseQuietHours(value)).toThrow('between 0 and 23');
+  });
+});
diff --git a/packages/cli/src/commands/iterate.ts b/packages/cli/src/commands/iterate.ts
index 14f09aee..15bdcc05 100644
--- a/packages/cli/src/commands/iterate.ts
+++ b/packages/cli/src/commands/iterate.ts
@@ -6,6 +6,7 @@ import { randomBytes } from 'node:crypto';
 import { spawnSync } from 'node:child_process';
 import { configDir } from '@profullstack/sh1pt-core';
 import { describeInput, resolveInput } from '../input.js';
+import { parsePositiveSafeInteger, parseQuietHours } from './iterate-options.js';
 
 // agentsCmd moved to root level — see https://github.com/profullstack/sh1pt/issues/235
 
@@ -293,8 +294,8 @@ iterateCmd
   .option('--agent <id>', 'claude | codex | qwen', 'claude')
   .option('--scope <area>', 'copy | pricing | onboarding | perf | bugs | all', 'all')
   .option('--cloud', 'schedule in sh1pt cloud instead of local cron')
-  .option('--interval <seconds>', 're-check interval in seconds', Number, 3600)
-  .option('--quiet-hours <start-end>', 'pause during these local hours, e.g. 22-08')
+  .option('--interval <seconds>', 're-check interval in seconds', parsePositiveSafeInteger, 3600)
+  .option('--quiet-hours <start-end>', 'pause during these local hours, e.g. 22-08', parseQuietHours)
   .option('--stop', 'remove the watch configuration')
   .option('--status', 'show current watch configuration')
   .action(async (opts: {