How I AI - Vibe-coding a kid-friendly AI fortune teller for your Halloween festivities | Marco Casalaina (Microsoft VP)

Episode Date: October 31, 2025

In this impromptu Halloween special, Marco Casalaina (VP of Products for Core AI at Microsoft) demonstrates how he uses GitHub Spark to quickly build a mobile app that generates kid-friendly fortunes for trick-or-treaters.—Where to find Marco Casalaina:LinkedIn: https://www.linkedin.com/in/marcocasalaina/X: https://x.com/amrcn_werewolf?lang=en—Where to find Claire Vo:ChatPRD: https://www.chatprd.ai/Website: https://clairevo.com/LinkedIn: https://www.linkedin.com/in/clairevo/X: https://x.com/clairevo—In this episode, we cover:(00:00) Intro(00:40) Marco’s Halloween fortune teller tradition(02:54) Using GitHub Spark to create a fortune teller app(04:32) Using Spec Kit for scoping out complex feature specs(06:53) Making fortunes more concrete and kid-friendly(10:20) Closing thoughts—Tools referenced:• GitHub Spark: https://github.com/features/spark• SpecKit: https://github.com/github/spec-kit• GitHub Copilot: https://github.com/features/copilot• Cursor: https://cursor.com/• Claude Code: https://www.claude.com/product/claude-code—Production and marketing by https://penname.co/. For inquiries about sponsoring the podcast, email [e-mail].

Welcome to a spooky and unplanned Halloween edition of How IAI. I'm Clairevaux, product leader and AI obsessive, here on a mission to help you use LLMs to do spooky stuff for your kids. Today, we had a haunted episode recording that we couldn't get to work. So instead of our regular scheduled programming, we did a quick Halloween vibe code that I think some of you parents out there will be inspired by. If you have other Halloween vibe codes, please share them with us in the comments and enjoy this very short episode of How I AI Halloween edition. Marco, we may, we may not be able to do our podcast today. We are haunted by expired corporate credit cards.

But you have a Halloween-based AI use case we're going to talk about instead just for a few minutes before we do schedule. I do. And maybe I'll kind of do it live on the fly here. and so why don't we not just talk about it when we actually do it so I'm dressed as Captain Picard right now as I do every year dressed as Captain Picard I mean it naturally fits with my you know brand and stuff like that of course I am a huge Star Trek fan I'm in the middle of strange new worlds right now season four but by night at least for Halloween I do something a little bit different I am the block fortune teller

So this is the Halloween party block that I live on here in Piedmont, California. And so we will block off the street. And all of our neighbors do crazy stuff. And so my neighbor across the street is going to have all this projection stuff going on. And they have like fire coming out of something. But what I do, well, I am a fortune teller. So traditionally, what I have done for the past few years is that I have pre-created fortune. So I set up this table.

and on this table I have a crystal ball and the crystal ball glows and stuff like that it's not a high-tech crystal ball it has nothing but a couple of LED lights in it but the kids come up and there's lots of kids in town hundreds of them really

come up and they will get their fortunes from this thing. Now in reality what I did was I in the past have pre-created these fortunes so I make a list of them with GPT3 and then GPT4 and I store them in a note on my phone and I kind of keep it between my legs

under the table and I'll kind of pick one at random. So when a kid comes up, I'll pick this one and I make that kind of kid-friendly fortunes. Now, this year, I was thinking about doing this, and since we're talking, I'm going to do this live now. I'm going to actually do this live. Are you going to read my fortune? We're going to make a fortune for you, yeah. So I think that for this, now there's lots of tools that I can use to do this. I can use lovable.

I can use Bolt. I can use B-Zero. I'm going to use GitHub Spark for this one. was not expecting a GitHub Spark today on Halloween. So this is exciting for me. How about that? Okay. So I'm going to say make a mobile app,

which when I click a button generates a new fortune in the context of a fortune teller. Okay. I don't think I need to tell it much more than that. It's probably going to kind of work on the first try. Well, we'll see. Let's see what this is. does. Now, you know, in other circumstances, I have sometimes given it like a list of things to

scroll between. You might have seen on the screen that earlier I had a chemistry ion flashcards app. My daughter is in honors chemistry, and she was at the time studying polyatomic ions, chlorate, per chlorate, you know, sulfate, stuff like that. And she needed to memorize the name to the formula of these polyethonic ions. And so I made a flash. And so I made a flashed, you know, flashcards app with this thing, which actually worked really well. I mean, I just gave it basically the list of the polyatomic ions. And it totally freaking did it in this kind of flashcard interface that worked on the phone. And so that was pretty nice.

That's kind of one of the reasons why I decided to go with GitHub Spark for this one is because I know that kind of worked for me before. And in a way, you could look at this as kind of being a flashcard app too. It's going to kind of make these flashcards of fortunes, I guess. Oh, my gosh. Well, I have a block party tomorrow. So I might steal your idea. You could do this.

You can have to pass for a fortune teller as well. Yeah. Oh my gosh. Okay. So this is going to, oh, it made a PRD. That's, you know, I love to see it. Let's see, can we see it? Let's see if we can see what it's doing while it's looted.

Oh, it does. Okay. So wow, it's really, it's going fast and furious over here. So it's totally writing this PRD over here. And now it's, it's made a page index. So it's starting to make the actual HTML. So it's going to write this in a. Gmail. And, you know, this is, this is common. And now it's got some CSS. So it's going to style

the page. But I mean, this is, this is vibe coding or anyway, front end vibe coding as we do it today. Now, in reality, though, I mean, when I'm doing real vibe coding projects and while this thing is working, since I actually already have this on my screen, I'm going to bust this out over here. Now, if I'm doing a real project, like a serious project, it's not just a little fortune teller app. Nowadays, I will 100% use spec kit. I absolutely do use spec kit. In fact, it so happens. I was earlier today working on just such a project. So I am, by the way, I'm VB products of CoreyI at Microsoft. However, I do come from an engineering background and I still code pretty much every day, something. So I'm working on this project and in this project where I did use

spec kit. So here, like this is a full feature specification that I'm working on. I have this whole agent thing that I'm working on. And I am adding this ability to give user feedback. So this agent will fill out a questionnaire for me. And that's cool. But I want to be able to pick a cell, a question and be like, no, no, you did that wrong. Fix it. And then the agent should just wake up and do it. When you use spec kit, and so like this is the proper way to write a spec, when you use spec kit, it does this stuff over here. So you see what it's going to do. It throws these questions at me. So it's like, wait a minute, how long should the feedback be? What if the user gives you a ton of feedback, then what do I do?

And it'll lob all of these questions at me while it does this. So SpecKit is cool. It's totally free. It works with, like, in this case, I'm using it with GitHub copoly, but it works with thought code and it works with cursor and all these other things. So that is super cool. I love it. It helps you write a better spec.

Oh, look at this. My app is here. Okay, tap to reveal your fortune, the cosmos. Okay. I'm very excited about this. Wow. Okay. That's a little bit too. Let me read this for people that are not on video. In the tapestry of the cosmos, the stars weave a path illuminated by your dreams.

Trust in their guiding light. Now, what I like about this is it is completely ambiguous and means nothing. Excellent, excellent fortune. But I bet you want it to be a little more fun and kids friendly for your case. And so over here on the left hand side, you can see that I'm saying, make each fortune only one sentence and make it kid friendly. So now I'm going to kind of prompt my way towards doing something and it's starting to generate again. So I mean, you got to admit, though.

I mean, it's pretty freaking good on the first truck. Really good. You know what? I haven't seen this GitHub Spark done live, but the design is actually really cute. So often in these vibe coding tools, you get these incredibly boring designs. but that is actually quite, quite lovely. Okay. All right.

Do we get it? It's done. It says it's done. Here we go. Let's see what happens. Mystic Oracle, what is my fortune? When you sprinkle kindness like fairy dust, the whole world transforms into a playground of magical adventures and shimmering smile.

That's it is. That is lovely and kid friendly. Still, maybe a little bit on the big word there. And on the abstract side? Yeah, on the abstract side. I mean, let's see. Make the fortunes. a little more concrete.

And let's make them a little more fun. And maybe a little more humorous. Yeah. Try not to use such big words. I mean, a lot of times, like, the kids that'll come up to my fortune telling booth, they'll be like, you know, two or three years old, you know? Yeah, yeah, yeah. And for them, sometimes I'll, like, not even use my little app thing.

And I'll be like, you're going to try a new food today. And it's going to be yummy. and their parents will be like, thank you. Your candy and your Halloween bag will multiply. But I mean, you know, Piedon is a small town and I actually know a lot of these parents and stuff like that. It's something that they come back at me later and they're like, you told my kid this fortune? Like I told one kid a fortune once and it was like, you're going to make a new friend today, which actually did come from the previous version of this generation.

And she said he was talking about it for the whole next day. She was like, the fortune teller said, I'm going to make a friend. in today. Like, this is going to be cool. Well, your kid's 15. Should I tell her she's going to get a car in her future? Now, okay, now we're going off the rails here. Okay, here we're going. You ready? Here's your, this is, this one's for you, Claire. Okay, ready? This week, you will find a shiny rock that looks like a slice of pizza and makes everyone giggle when you do like that. That would entertain my six-year-old. I mean, that is very concrete for sure. And now, you know, your six-year-old, yeah, we'd totally be looking for, Oh, where's that rock that looks like the slice of pizza?

I'm going to find it. That's exactly right. Okay, I... One more. Let's see. One more. This week, okay, again with the rock. Maybe it's going a little over much on the rocks here.

You know, or whatever a rock that looks like a cupcake. Frikels and that. I mean, this is why you can get an integration test these things. Are these all rocks? Oh, no. Today, a fluffy squirrel will steal your snack, but then share a secret about the best hiding spots in the park. Okay.

I'm surprised this. Squirrel is not sharing the secret about the best rocks in the park. So, I mean, that name. Got it. Okay. I, um, you know, it's, it's Halloween. It's almost 11 a.m. I've got, my block parties tomorrow.

So we're blocking off the street. We're doing a post-Hlloween. Everybody bring your candy so you can give it a more away party. And I'm going to do this. I'm going to hook it up to voice. Sweet. Give it a like a, spooky fortune teller voice and set it up out front.

Well, Marco, despite our haunted podcast episode, we will get you back on to actually talk about Spectrum and development, but thank you for doing our first and maybe an annual tradition of our Halloween AI, How I AI episode. Thank you for showing this off. Every year. We'll have like different elements to Halloween. Perfect. Well, we'll get you back on on the pod.

And I think I'm going to go cut this and share it. Thanks so much for watching. If you enjoyed this show, please like and subscribe here on YouTube or even better, leave us a comment with your thoughts. You can also find this podcast on Apple Podcasts, Spotify, or your favorite podcast app. Please consider leaving us a rating and review, which will help others find the show. You can see all our episodes and learn more about the show at how IAIIPod.com. See you next time.