TLDR Dev 2026-04-16
Inside OpenAI Codex 🤖, Gemini Mac app 🖥, Caveman for LLMs 🪨
How OpenAI built Codex: inside the agent loop and harness (14 minute read)
OpenAI Codex uses a single shared Rust-based "harness" to power its cross-platform coding agent across multiple client surfaces like CLI, web, VS Code, and macOS. At its heart, an agent loop orchestrates model inference, tool calls, and prompt updates, with prompt caching and context compaction built-in. All clients interact with the Codex core via a stable, bidirectional JSON-RPC App Server protocol.
Things you didn't know about indexes (12 minute read)
Database indexes speed update retrieval by providing a sorted structure that bypasses slow full table scans. However, they come with trade-offs, making writes slower, consuming storage, and requiring careful implementation to avoid pitfalls like incorrect composite index order or applying functions to indexed columns. Tools like `EXPLAIN` help diagnose index usage, while specialized types such as functional indexes (for expressions) and partial indexes (for data subsets) address specific query patterns.
Under the hood of MDN's new frontend (30 minute read)
MDN rebuilt its frontend from a React SPA to a Lit-based architecture using web components for interactivity and custom server components for static templating, solving the core problem of React being unable to reach into documentation HTML. The new setup auto-discovers and lazy-loads only the JS/CSS each page actually needs, uses Declarative Shadow DOM for pre-JS rendering, and switches from Webpack to Rspack, dropping dev server startup from two minutes to two seconds.
Do You Even Need a Database? (15 minute read)
Simple file-based storage is often highly performant for many applications. Benchmarks against SQLite show that methods like in-memory maps are better for ID lookups, so databases are only essential for needs like scaling past single-server RAM limits, complex queries, concurrent writes, or atomic transactions.
Why AI Sucks At Front End (4 minute read)
AI is great at scaffolding generic, unoriginal UI, but falls apart the moment you need bespoke interactions, pixel-perfect layouts, or accessibility. The root causes are that it's trained on outdated CSS, can't actually see what it renders, and doesn't understand architectural reasoning.
Why AI hasn't replaced human expertise—and what that means for your SaaS stack (7 minute read)
Stack Overflow reports that advanced questions on its platform have doubled since 2023. AI handles the easy stuff, but 75% of devs turn to humans when they don't trust AI output. Devs value the comments and discussion around answers more than the answers themselves, which is something AI can't replicate by collapsing discourse into a single confident paragraph.
Cal.com Goes Closed Source: Why AI Security Is Forcing Our Decision (5 minute read)
Cal.com is moving its main product from open source to closed source after five years. This difficult decision was made primarily due to escalating security threats from AI, which can now rapidly find and exploit vulnerabilities in open-source code. While the core product is closing, a separate, open-source version called Cal.diy will be released under an MIT license for hobbyists and developers.
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