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

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 jordan@penname.co._

Claire VohostMarco Casalainaguest
Oct 30, 202511mWatch on YouTube ↗

At a glance

WHAT IT’S REALLY ABOUT

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

  1. A technical hiccup (“haunted” by expired corporate credit cards) turns the episode into a short, improvised Halloween vibe-coding session.
  2. 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.
  3. 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.
  4. 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.

IDEAS WORTH REMEMBERING

5 ideas

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.

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.

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.g., silly events), which better matches kids’ expectations and attention.

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.

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.

WORDS WORTH SAVING

5 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

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”)

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