Vibe-coding a kid-friendly AI fortune teller for your Halloween festivities | Marco Casalaina

Vibe-coding a kid-friendly AI fortune teller for your Halloween festivities | Marco Casalaina

How I AIOct 31, 202511m

Claire Vo (host), Marco Casalaina (guest)

Halloween block-party fortune teller traditionVibe coding a mobile app with GitHub SparkPRD generation and rapid UI scaffoldingPrompt iteration for tone, length, readabilityMaking fortunes concrete, funny, kid-safeSpec Kit for feature scoping and requirement questionsTesting/validation (pattern repetition, “integration test”)

In this episode of How I AI, featuring Claire Vo and Marco Casalaina, Vibe-coding a kid-friendly AI fortune teller for your Halloween festivities | Marco Casalaina explores building a kid-friendly AI fortune teller app with GitHub Spark A technical hiccup (“haunted” by expired corporate credit cards) turns the episode into a short, improvised Halloween vibe-coding session.

Building a kid-friendly AI fortune teller app with GitHub Spark

A technical hiccup (“haunted” by expired corporate credit cards) turns the episode into a short, improvised Halloween vibe-coding session.

Marco Casalaina demonstrates GitHub Spark by generating a simple mobile-friendly fortune teller app that creates a new fortune on button tap, starting from a minimal prompt.

They iteratively refine the output via prompting—shortening fortunes, making them kid-friendly, then pushing for more concrete, humorous, simpler-language predictions suitable for toddlers.

Marco also briefly contrasts quick demos with “serious” work, recommending Spec Kit to pressure-test requirements by asking clarifying questions and producing stronger feature specs.

Key Takeaways

Start with the smallest prompt that can work.

Marco begins with a one-line ask (“Make a mobile app… generates a new fortune”), letting the tool scaffold a PRD and UI quickly before refining details.

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Use iterative prompting to shape tone and audience fit.

They progressively constrain the model: one sentence, kid-friendly, more concrete, more humorous, and simpler vocabulary—showing how small edits steer outputs fast.

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Abstract “mystic” fortunes are easy; kid-friendly usefulness requires specificity.

The first fortune is poetic but meaningless; the improved versions become actionable and playful (e. ...

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Watch for repetitive patterns and test outputs like a product.

When multiple fortunes start repeating “shiny rock” variations, Marco calls out the need to “integration test these things,” highlighting quality checks even in lightweight demos.

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Real projects benefit from structured spec workflows, not just vibe coding.

Marco recommends Spec Kit for complex features because it interrogates ambiguous requirements (length limits, edge cases) and helps produce a robust spec before implementation.

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Vibe-coded prototypes can be extended into real experiences (voice, ambience).

Claire plans to add a spooky voice layer for a block party, illustrating how quick apps become delightful demos when paired with simple UX enhancements.

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Notable Quotes

So why don't we not just talk about it, why don't we actually do it?

Marco Casalaina

Oh, my gosh… it made a PRD.

Claire Vo

‘In the tapestry of the cosmos…’ Now, what I like about this is it is completely ambiguous and means nothing.

Claire Vo

You gotta, like, integration test these things. Are these all rocks?

Marco Casalaina

When I'm doing real… projects… I will 100% use SpecKit.

Marco Casalaina

Questions Answered in This Episode

In GitHub Spark, what prompt details most influence whether it generates a PRD first versus jumping straight into code/UI?

A technical hiccup (“haunted” by expired corporate credit cards) turns the episode into a short, improvised Halloween vibe-coding session.

Get the full analysis with uListen AI

What specific prompt patterns help reduce repetition (like the recurring “rock” motif) in short-form generations such as fortunes?

Marco Casalaina demonstrates GitHub Spark by generating a simple mobile-friendly fortune teller app that creates a new fortune on button tap, starting from a minimal prompt.

Get the full analysis with uListen AI

How would you design a “kid-age slider” (toddler to teen) so the app reliably changes vocabulary complexity and humor style?

They iteratively refine the output via prompting—shortening fortunes, making them kid-friendly, then pushing for more concrete, humorous, simpler-language predictions suitable for toddlers.

Get the full analysis with uListen AI

What safety constraints would you add to prevent scary, sensitive, or overly predictive fortunes (e.g., health, family, death) for children?

Marco also briefly contrasts quick demos with “serious” work, recommending Spec Kit to pressure-test requirements by asking clarifying questions and producing stronger feature specs.

Get the full analysis with uListen AI

Can Spec Kit be used to define a test plan for generative outputs—like diversity, readability grade level, and “no repeats” checks—before coding?

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Transcript Preview

Claire Vo

Welcome to a spooky and unplanned Halloween edition of How I AI. I'm Claire Vo, 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. [upbeat music] Marco, we may, we may not be able to do our podcast today. We are haunted by-

Marco Casalaina

We are haunted

Claire Vo

... expired cr- ex- expired corporate credit cards. But you have a, a Halloween-based AI use case [chuckles] we're gonna talk about instead, just for a few minutes before we reschedule.

Marco Casalaina

I do, I do, and maybe I'll, I'll kind of do it live on the fly here.

Claire Vo

Yeah.

Marco Casalaina

And so why don't we, why don't we not just talk about it, why don't we actually do it? So I'm dressed as Captain Picard right now, uh, as I do every year, dressed as Captain Picard. I mean, it naturally fits with my-

Claire Vo

fits

Marco Casalaina

... you know-

Claire Vo

Brand

Marco Casalaina

- 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 4. But, uh, 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, you know, my neighbor across the street is gonna have all this projection stuff going on, and they have, like, fire coming out of something and... But what I do, well, I am a fortune teller. So traditionally, uh, what I have done for the past few years is that I have pre-created fortunes. So I set up this table, and on this table, uh, I have a, a, 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, you know, hundreds of them really, come up, and they, 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 GPT-3 and then GPT-4, 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 a kind of kid-friendly fortunes. Now, this year, I, I was thinking about doing this, and since we're talking, I'm gonna do this live now.

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