> hello, world_

Cyrus David Pastelero

What I cannot build, I do not understand.

I ship a lot, and I can explain all of it. 19 projects written up here, 11 of them live. Some I built twice to find out what actually mattered. Currently trying to survive in Singapore.

Fun fact: I grew up playing Minecraft, which taught me that even the most complex structures start with a single block.

GitHub LinkedIn Email

Flagship projects

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Isip

On-Device AI

An iOS app that turns your completed tasks, voice notes, and photos into journal entries automatically using Apple Intelligence. Runs entirely offline and needs no account.

SwiftUI · Foundation Models · SwiftData

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Arkitekto

8K+ questions

Building an online review platform for aspiring Filipino architects preparing for the Architect Licensure Examination. What creating 8,000+ practice questions and implementing spaced repetition taught me about EdTech, content quality, and building for a niche audience.

Next.js · Supabase · React 19

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JustCar

49K+ vehicles

Solving the frustration of comparing cars across fragmented sources. What aggregating 49,000+ vehicles taught me about data quality, scraper maintenance, and why boring technology choices are often the right ones.

Next.js · TypeScript · Supabase

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Claude Code Config

65 rules

Open sourcing my Claude Code configuration with 29 agents, 60 commands, 60 skills, and 65 rules. What building a setup that size taught me about agent orchestration, developer experience, and why sharing tooling configs is worth the effort.

Claude Code · Shell · AI Agents

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How I work

I pick boring technology when it wins. JustCar needed search, so I tried Postgres trigram indexes before reaching for Elasticsearch. Postgres handled 49,000 records fine, so Elasticsearch never got added.

I ask what the worst outcome is before I start. That is why I can move fast. The AWS talk I gave in Cebu was mostly about this: build the MVP, bound the bill at zero.

And I write down what I got wrong. 13 of these case studies have a section on what I would do differently.

Hanyu, built in React Native and SwiftUI

postmortems written

rules constraining my AI output

Writing

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Technical deep-dives, system design, and what building real products actually taught me.

I Open Sourced My Personal Operating System

April 1, 2026

Why I turned years of notes on focus, fitness, career, engineering, and mindset into a structured public knowledge base. And what writing it all down forced me to confront about how I actually operate.

I Built My Brother a Portfolio with a Custom CRM — In a Weekend

March 30, 2026

A freelance portfolio used to mean a Behance page and a Google Sheet for tracking clients. I built my brother a full platform with a 6-stage lead tracker, contract generator, and rate calculator — all client-side, no backend. Here is why branding and tooling are the real moats in the age of AI.

I Built a Board Exam Reviewer for Filipino Architects

February 9, 2026

How I went from "there should be a better way to study" to shipping a platform with 8,000+ practice questions, spaced repetition, and mock exams for the Philippine Architect Licensure Examination.

About

When I'm not shipping features at 2am, you'll find me chasing a new hobby: currently hiking, previously Muay Thai, cycling, and running. I'm the type who dives deep into something, then moves on to the next obsession. Still think Minecraft is one of the best games ever made.