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1+ hour, 27+ min ago (516+ words) By Leonardo Policarpo Software Engineer | Backend Architecture & IoT Enthusiast " Leia a vers'o em Portugu's aqui Recently, I tackled a common challenge in large corporate scenarios: the need to create new, high-performance, scalable features that consume data from a consolidated database, without compromising the stability of the central system. The goal was to architect a Read-Only Microservice to feed data visualization interfaces and export routines. The business requirement was speed of delivery; the technical requirement I imposed on myself was engineering excellence and long-term maintainability. In this article, I share the architectural decisions taken to ensure a robust and decoupled solution using Node.js, Clean Architecture, Prisma, and Docker. The scenario involved complexities typical of robust systems that have grown organically over the years: To ensure the project's longevity, I adopted Clean Architecture. The main goal was to isolate business rules…...

1+ hour, 27+ min ago (619+ words) How to write fast, reliable tests for workflows that span hours Testing long-running workflows is tricky. Your function waits for callbacks, retries failed operations, and spans multiple invocations. How do you test that without actually waiting hours or deploying to AWS? The AWS Durable Execution SDK includes a testing library that solves this. You can run your durable functions locally, skip time-based waits, inspect every operation, and verify behavior without touching AWS. Let's see how. The SDK provides testing tools for different scenarios: LocalDurableTestRunner runs your function in-process with a simulated checkpoint server. Tests execute in milliseconds, even for workflows that would normally take hours. This is what you'll use for most testing. CloudDurableTestRunner tests against deployed Lambda functions in AWS. Use this for integration tests or when you need to verify behavior in the actual AWS environment. run-durable CLI…...

1+ hour, 28+ min ago (619+ words) When the Kiroween Hackathon was announced, I wanted to try something different " something playful, something nostalgic, and something that would push the boundaries of what an AI-powered IDE like Kiro could help me build. Most hackathon projects either look forward into the future or try to solve an immediate problem. I wanted to look backward. That's how I came up with MCP Time-Traveler " an app that reconstructs historical tech stacks from 2015 to 2025 across Node, Python, and Ruby, using real version data from npm, PyPI, and RubyGems. What surprised me most wasn't the idea. It was how quickly Kiro turned it into a real, working project. This is the story of how it came to life. " Where the Idea Started Developers often discuss "what stack should I use?" But rarely do we ask, "what did this stack look like five or…...

1+ hour, 42+ min ago (345+ words) Token-Oriented Object Notation offers 30-60% token reduction and 4.8x faster parsing. Here's why that matters and how to use it. JSON is everywhere. It's the backbone of modern web development, API communication, and data storage. But here's the thing: JSON is verbose. Every quote, comma, and brace adds up. In AI/LLM applications, this verbosity translates directly to higher costs and limited context windows. When you're paying per token, those extra characters matter. Enter TOON (Token-Oriented Object Notation) " a format that promises to solve these problems while maintaining (or improving) human readability. TOON achieves 30-60% fewer tokens compared to JSON. Let's see why: Notice the difference? No quotes around keys. No commas. No braces. Just clean, indentation-based structure. The TOON version uses approximately 40% fewer tokens. TOON isn't just more compact " it's also up to 4.8x faster to parse. This matters for real-time applications, high-throughput…...

1+ hour, 53+ min ago (369+ words) Most IoT projects today lean heavily on Python, C, or Node.js, and that's fine. But during my recent academic paper selection process, I came across "The Benefits of Tierless Elixir/Potato for Engineering IoT Systems, and it completely shifted how I think about building IoT architectures. The paper raised a question that stuck with me: why do we keep separating the logic, runtime and UI layers in IoT systems if functional, tierless architectures can unify everything? That curiosity, combined with the influence of a professor(Adolfo Neto) who strongly advocates for functional programming and the BEAM, pushed me to test this idea in practice. So I built a complete IoT prototype using Elixir, Circuits, Raspberry Pi, and Phoenix LiveView. And honestly? It felt like IoT the way it should be: supervised, fault-tolerant, reactive, and consistent from the edge to…...

2+ hour, 13+ min ago (349+ words) Building a real-world client application is more than just writing code'it's about creating smooth, clean, reliable user experiences that scale in production. In this post, I'm sharing selected UI/UX previews from a recently delivered mobile app project, built completely from scratch with Flutter and Supabase. I recently completed a client project where I designed and developed a production-ready mobile application tailored for job placement and talent management workflows. To respect confidentiality and protect core business logic, I'm sharing only selected UI/UX mockups and visual screens from the project. These previews highlight the design system, visual hierarchy, and real-world usability that guided the development process. " Note: To maintain client confidentiality and protect the core product idea, I'm only sharing selected screens and mockups rather than the entire application flow. The application was designed for a company working in job…...

2+ hour, 15+ min ago (211+ words) The task is to create a function to return the n-th number string in a sequence. n starts from 1. The boilerplate code function getNthNum(n) { // your code here } Start with the first number if(n === 1) return "1"; To get the next number, describe the digits of the previous ones. Count how many times the same digits appear one after the other. When it changes to a new digit, write the count down and the digit being counted. let result = "1"; for (let i = 2; i The task is to create a function to return the n-th number string in a sequence. n starts from 1. Start with the first number To get the next number, describe the digits of the previous ones. Count how many times the same digits appear one after the other. When it changes to a new digit, write the count down…...

2+ hour, 19+ min ago (76+ words) For this project, I wanted to practice working with external APIs that require an API key. The OMDb API is perfect for this " free, fast, and provides detailed movie information. This project includes two versions: By building this app, I learned how to work with authenticated APIs, handle search results, manage missing data, and build a better UI using Streamlit. The Movie Search App allows you to: OMDb requires a free API key. Get one here:...

2+ hour, 24+ min ago (236+ words) Part 6 of The Hidden Failure Point of ML Models Series If overfitting and underfitting are the symptoms, the Bias'Variance Tradeoff is the underlying physics driving them. Most explanations of bias and variance are abstract and mathematical. But in real ML engineering, this tradeoff is practical, measurable, and essential for building resilient models that survive production. This article will finally make it intuitive. Bias is how wrong your model is on average because it failed to learn the true pattern. High bias happens when: High Bias " Underfitting Variance is how sensitive your model is to small variations in the training data. High variance happens when: High Variance " Overfitting You can think of bias and variance as opposite forces: Your goal isn't to minimize both. Your goal is to find the sweet spot where total error is minimized. Imagine shooting arrows at…...