Build your own alien meeting reminder for your Mac

What this actually is

A tiny Mac app that lives in your menu bar. A few minutes before each meeting in your calendar, a little alien flies a saucer across your screen, pops its head up, and tells you what's coming. Then it zips off. It's click-through, so it can't get in the way of what you're typing, and it's gone in seven seconds.

It reads your meetings from the Calendar app on your Mac — which means it picks up everything already in there: iCloud, any Google accounts you've added, and any calendar feed you subscribe to. Mine reads a ClickUp feed that way, so tasks I add in ClickUp fly across my screen even though the app has never heard of ClickUp.

There's no account, no login, no API key and nothing to connect. Everything stays on your Mac.

What you need before you start

Three things, and only one of them costs money:

1. A Mac running macOS 14 (Sonoma) or newer. Apple menu → About This Mac.
2. Claude Code, on a paid Claude plan. This is the part that costs. It's the tool that does the building for you.
3. Apple's build tools. A one-line install, and Claude walks you through it if you haven't got them.

No developer account, no App Store, no £99 Apple fee — because you're building it yourself rather than downloading a finished app.

Step 1 — Get Claude Code on your Mac

Skip this if you've already got it.

1. Go to claude.ai/code and follow the install instructions for Mac.
2. Sign in with your Claude account.
3. Open Terminal (press ⌘ Space, type "Terminal", press Return), type claude and press Return. If it starts talking to you, you're in.

That's the only genuinely new tool. Everything after this is Claude doing the work.

Step 2 — Download the code

Download Alien Reminder by Incuv8or (1.7 MB)

1. Double-click the zip to unzip it. You'll get a folder.
2. Drag that folder somewhere sensible — Documents is fine. Not Downloads, because you'll want it again if you ever rebuild.

Step 3 — Point Claude Code at the folder

1. In Terminal, type cd (with a space after it) — don't press Return yet.
2. Drag the folder from Finder onto the Terminal window. It fills in the path for you.
3. Now press Return.
4. Type claude and press Return.

You're now talking to Claude, inside the folder with the code.

Step 4 — Paste this in

Copy the whole block below and paste it into Claude Code. That's the entire job — it does the building and tells you what to click.

I've downloaded a folder of Swift source code for a small Mac app called Alien Reminder
by Incuv8or. It puts a little alien in my menu bar who flies a saucer across my screen a
few minutes before each meeting starts. Please build it and get it running on my Mac.

I am not a developer. Explain what you're doing in plain English, don't assume I know the
technical words, and if something fails, diagnose it and tell me exactly what to click.

Please do this in order:

1. Check my Mac can build it. It needs macOS 14 (Sonoma) or newer — run
   `sw_vers -productVersion` and tell me if I'm too old. Then run `swift --version`. If
   that fails, tell me to run `xcode-select --install`, wait for the download, then carry
   on. Don't make me install the whole of Xcode unless the build actually fails without it.

2. Build it. From inside the folder, run ./scripts/build-app.sh. If it errors, read the
   error and fix it — don't just hand me the error message.

3. Open the app. It's in the build folder, called "Alien Reminder by Incuv8or.app". There's
   no window and no Dock icon — it's a small alien in the menu bar at the top right of my
   screen. Tell me to look for it.

4. Calendar permission. macOS will ask for access to my calendar. Tell me to click Allow,
   and explain that the app reads my meetings from the Calendar app and can't do anything
   without it. If I've already said no by accident, walk me through
   System Settings > Privacy & Security > Calendars.

5. Prove it works. Tell me to press Control-Option-Command-A. An alien should fly in from
   the left, pop up out of the saucer, show a speech bubble, and zip off to the right. If
   nothing happens, work out why.

6. Set it up with me. Open Settings from the menu bar icon and walk me through: which
   calendars to watch (they're grouped by account, so I can untick a client's), how many
   minutes' warning I want, the alien's size and colours, and whether it opens at login.

7. Tell me the two shortcuts worth remembering: Control-Option-Command-A to test it, and
   Control-Option-Command-X to dismiss a reminder that's on screen.

If I ask you to change how it looks, the colours live in Sources/AlienHUD/Palette.swift and
the animation in Sources/AlienHUD/Alien.swift. Change them, rebuild, and show me.

Expect it to take a couple of minutes. If something fails, tell Claude what happened rather than giving up — reading its own errors is the thing it's best at.

Step 5 — Say yes to the calendar

macOS will ask whether the app can see your calendar. Click Allow. Everything the app knows comes from your calendar, so it can't do anything at all without this.

If you hit the wrong button, macOS won't ask twice — go to System Settings → Privacy & Security → Calendars and switch it on there.

Step 6 — Watch it work

Look for the alien in your menu bar, top right of your screen.

Press Control-Option-Command-A and it'll fly across. That's the test-fire shortcut, and it's the fastest way to know it's working without waiting for a real meeting.

Step 7 — Set it up the way you want

Open Settings from the menu bar icon:

• Which calendars. Every calendar on your Mac, grouped by the account it came from. Everything starts ticked, so untick a client's calendar if you don't want their meetings interrupting you.
• How much warning. Five minutes by default. Anything from one to sixty.
• The alien's size. Bigger for filming, smaller for subtle.
• Colours. Three palettes; it rotates by default, or pin it to one.
• Open at login, so it's always watching.

Shortcut	What it does
⌃⌥⌘A	Fire a test reminder right now
⌃⌥⌘X	Dismiss the reminder that's on screen

Making it yours

This is the bit I'd actually encourage. Ask Claude to change it.

• "Make the alien my brand colours" — the palettes are in one file, and Claude will ask for your hex codes or pull them off your website.
• "Make the alien bigger and slow the animation down"
• "Change what it says"
• "Give it two antennae instead of one"

The whole app is about a dozen small files with comments explaining what each part does. You can't break it in a way Claude can't undo — and if you do, delete the folder and unzip it again.

If something goes wrong

"The alien never appears." Open the menu bar icon. The top line tells you what it thinks it's doing. If it says Waiting for calendar access, that's your answer — Step 5.

"It appears for meetings I don't care about." Settings → untick that calendar.

"It asked for calendar permission again." Normal after a rebuild — macOS treats each freshly-built copy as a new app. Click Allow.

"It's on the wrong screen." It appears on whichever screen your mouse is on.

"The build failed." Paste the error to Claude and ask it to fix it. That's not a cop-out — diagnosing build errors is exactly what it's for.

Licence, plainly

Yours to use and to change as much as you like. Not yours to resell. If you make something good with it, I'd love to see it.