Context engineering: the invisible skill that separates good AI agents from mediocre ones

Imagine you hire a brilliant consultant. They have two PhDs, speak seven languages, and solve problems you didn’t even know you had. You sit them in a room and say: “I need you to refactor the authentication in the project.” The consultant looks at you, nods, and asks: “What project?” You haven’t given them access to the code. You haven’t explained the architecture. They don’t know if you use JWT tokens or session cookies. They don’t know what language you’re using, how many microservices you have, or why the last migration attempt ended in disaster. ...

March 11, 2026 · Fernando

DIY Codex Automations: Nocturnal Agents with Claude Code and systemd

Two weeks ago, OpenAI introduced Codex Automations. The idea: define a trigger (a cron job, a push, a new issue), write instructions in natural language, and an agent runs it solo in an isolated worktree. No human intervention. While you sleep, the agent triages issues, summarizes CI failures, generates release briefs, and even improves its own instructions. Sounds like magic, right? And it is, a little. But there’s one catch they didn’t emphasize too much in the keynote: you need the Codex App running on your desktop. macOS or Windows only. No headless servers. No running it on a mini PC and forgetting about it. ...

March 11, 2026 · Fernando

Your AI coding agent is a while loop with delusions of grandeur

The first time I used Claude Code to refactor an entire module, I had an almost mystical experience. I described what I wanted, went to grab a coffee, and when I came back there was a pull request with 14 changed files, updated tests, and a decent commit message. “This is magic,” I thought. It’s not magic. It’s a while loop. Michael Bolin from OpenAI recently published an article breaking down the internal workings of Codex CLI. And it turns out the secret behind AI coding agents isn’t some revolutionary algorithm or mysterious neural network. It’s a loop that calls an LLM, executes tools, and repeats until there’s nothing left to do. ...

March 11, 2026 · Fernando

From /simplify to the Jedi Council: How I Built a Code Review with Kent Beck, Martin Fowler, and Mike Acton

Claude Code includes a slash command called /simplify that automatically reviews your code. I ran it on a hefty diff — about 500 lines across 8 files — and the results were… interesting. It found things I wouldn’t have noticed, but it also wasted my time pointing out stuff that didn’t matter. So, I took it apart and rebuilt it piece by piece. What Does /simplify Do? It’s a skill that comes bundled with Claude Code (you don’t install it). It launches three agents in parallel, each looking at the same diff from a different angle: ...

March 9, 2026 · Fernando

/loop in Claude Code: the cron that lives and dies with your terminal

For months, I’ve been running Claude Code tasks using a homemade cron. A Bash script that starts a headless session, feeds it a prompt, waits for it to finish, and then closes. It works. Barely, but it works. I’ve got it up on GitHub if anyone’s interested. Then on Friday, with version 2.1.71, Anthropic introduced /loop. A native scheduler. Built directly into Claude Code sessions. My first reaction was: “They killed my project.” ...

March 9, 2026 · Fernando

33,000 lines of XML to tell you heavyWork() is slow: how I tamed xctrace for LLMs

Last week I was profiling a Swift app with Instruments. Standard procedure: xctrace record, xctrace export, copy the XML to Claude Code’s context, ask it to find the hotspots. Claude responds: “The XML is too large, I can’t process it reliably.” 33,553 lines of XML. For a program with two functions. The real problem xctrace export is a fantastic tool. It gives you everything: every sample, every backtrace, every frame with its binary, memory address, and UUID. It’s exhaustive, precise, and complete. ...

March 8, 2026 · Fernando

Anatomy of Claude Code's Remote Control: The Hidden API You Can't Use Yet

On February 25, 2026, Anthropic announced Remote Control for Claude Code. The idea: fire up Claude Code on your terminal, sit back on your couch with your phone, and continue the session through claude.ai. No SSH. No tmux. No remote terminal windows. Cool. In theory. Because in practice, when I enabled it (/rc in the terminal), I got a URL, opened it on my phone, logged in… and claude.ai hit me with a “this feature is not active in your organization.” February 2026, Max 5x account, paying religiously. And nothing. ...

February 27, 2026 · Fernando

Claude Code Native Build: 100MB Binary to Ditch Node for Good

A 100-Megabyte Binary for a CLI Anthropic just announced that Claude Code is now available as a native build. Translation: a binary executable you can install with a curl command that doesn’t need Node.js. Sounds good, right? One command, no dependencies, background auto-updates. Any CLI tool’s dream. But there’s a catch: the binary weighs 100MB. To put this in perspective, the git binary weighs about 3MB. curl is less than 1MB. Even Go, which has a reputation for generating fat binaries, rarely exceeds 15-20MB. ...

January 27, 2026 · Fernando

claudevm.bundle: the hidden 10.8 GB Ubuntu VM in Claude Desktop

The Surprise of 10 GB You install Claude Desktop on your Mac. Everything seems fine; the app doesn’t take up much space. But one day, you check your disk and find this: ~/Library/Application Support/Claude/vm_bundles/claudevm.bundle 10.8 GB. Yes: one single file called claudevm.bundle, tucked away in Claude’s vm_bundles folder, taking up almost eleven gigabytes of your disk space. Ten gigabytes for a chatbot? What does it contain— the extended edition of The Lord of the Rings trilogy? ...

January 25, 2026 · Fernando

Your Terminal is Burning Battery Like It's Mining Bitcoin

The crime scene Zaragoza, Hotel Pilar Plaza café. A latte, views of the basilica, and yours truly with a shiny new MacBook Air M3 ready to work a couple hours with Claude Code before a meeting. Two hours later: battery at 15%. Red alert. Panic. But how? I was just in a terminal writing code. No video, no Zoom, nothing that would justify this kind of consumption. I open Activity Monitor, Energy tab, and there’s the culprit: Ghostty, with an accumulated consumption of 3,600 over the last 12 hours. For context, Brave Browser consumed 125. Zoom with video, 99. Claude (desktop app), 46. ...

January 24, 2026 · Fernando