Applied AI, agents, evaluation, retrieval, developer tools, and production engineering.https://alexmlewis.com/https://alexmlewis.com/writing/the-fail-open-i-shipped-three-times/https://alexmlewis.com/writing/the-fail-open-i-shipped-three-times/A completeness check that had to be safe over time, three state machines that each leaked a fail-open, and the pure function that finally fixed it.Mon, 10 Aug 2026 00:00:00 GMTAgentshttps://alexmlewis.com/writing/ground-truthing-llm-judges/https://alexmlewis.com/writing/ground-truthing-llm-judges/LLM-as-judge is the default eval now, but a judge is just another unreliable model. Here is how to check whether its verdicts correlate with real outcomes, and catch the leniency bias most judges have.Tue, 21 Jul 2026 00:00:00 GMTEvaluationAgentshttps://alexmlewis.com/writing/the-agent-harness-ate-my-workflow/https://alexmlewis.com/writing/the-agent-harness-ate-my-workflow/A year ago I kept a 6,000-line migration coherent with a hand-maintained progress file. Most of that scaffolding now ships inside the agent CLIs. Here is what the harness absorbed, and the part it still cannot.Tue, 21 Jul 2026 00:00:00 GMTAgentsDeveloper Toolshttps://alexmlewis.com/notes/how-this-site-is-built/https://alexmlewis.com/notes/how-this-site-is-built/How this site is builtTue, 21 Jul 2026 00:00:00 GMTMetaAstrohttps://alexmlewis.com/writing/50-ai-skills-for-the-parts-of-your-day-you-never-get-around-to/https://alexmlewis.com/writing/50-ai-skills-for-the-parts-of-your-day-you-never-get-around-to/The biggest productivity gap is the work around the code: context gathering, note-taking, and status updates. I built 50 AI workflow skills to make those 15-minute tasks actually happen every day.Mon, 23 Mar 2026 00:00:00 GMTAgentsDeveloper Toolshttps://alexmlewis.com/writing/use-insights-to-improve-your-claude-code-setup/https://alexmlewis.com/writing/use-insights-to-improve-your-claude-code-setup/I ran /insights in Claude Code and walked through what it found - friction patterns I hadn't noticed, CLAUDE.md rules I should have written weeks ago, and what changed after I applied the suggestions.Fri, 13 Mar 2026 00:00:00 GMTDeveloper ToolsAgentshttps://alexmlewis.com/writing/reward-engineering-and-evaluation-making-your-system-learn-what-matters/https://alexmlewis.com/writing/reward-engineering-and-evaluation-making-your-system-learn-what-matters/This is the third post in our series on probabilistic prompt pipelines. In our first post, we explored why static prompts become bottlenecks. The second…Wed, 29 Oct 2025 00:00:00 GMTEvaluationRetrievalhttps://alexmlewis.com/writing/building-the-selector-retrieval-bandits-and-cold-start-solutions/https://alexmlewis.com/writing/building-the-selector-retrieval-bandits-and-cold-start-solutions/This is the second post in our series on probabilistic prompt pipelines. In the first post, we explored why static prompts become bottlenecks and saw a…Wed, 09 Jul 2025 00:00:00 GMTRetrievalEvaluationhttps://alexmlewis.com/writing/why-static-prompts-fail-and-how-probabilistic-selection-solves-real-problems/https://alexmlewis.com/writing/why-static-prompts-fail-and-how-probabilistic-selection-solves-real-problems/This is the first post in a four-part series on building production-ready probabilistic prompt pipelines. By the end of this post, you'll understand why…Fri, 27 Jun 2025 00:00:00 GMTRetrievalEvaluationhttps://alexmlewis.com/writing/claude-code-the-hidden-testing-ground-for-ai-agents/https://alexmlewis.com/writing/claude-code-the-hidden-testing-ground-for-ai-agents/I've been using Claude Code daily since it launched for general use. After months of working with it, I've developed a theory about what's actually…Wed, 25 Jun 2025 00:00:00 GMTAgentshttps://alexmlewis.com/writing/staying-sane-on-a-6-000-line-refactor-with-claude-code/https://alexmlewis.com/writing/staying-sane-on-a-6-000-line-refactor-with-claude-code/As large language models become more capable, it's tempting to rely on them for increasingly complex engineering tasks. Tools like Anthropic's Claude Code…Fri, 20 Jun 2025 00:00:00 GMTAgentsDeveloper Toolshttps://alexmlewis.com/writing/mastering-conditional-types-in-typescript/https://alexmlewis.com/writing/mastering-conditional-types-in-typescript/Conditional types give you type-level if/else logic in TypeScript. How to build recursive utilities like DeepNullable, use distributive conditionals and infer, and avoid the common pitfalls.Wed, 11 Jun 2025 00:00:00 GMTTypeScripthttps://alexmlewis.com/writing/understanding-useeffect-vs-uselayouteffect-in-react-a-comprehensive-guide/https://alexmlewis.com/writing/understanding-useeffect-vs-uselayouteffect-in-react-a-comprehensive-guide/useEffect runs after the browser paints; useLayoutEffect runs before it. When to use each, with performance notes and edge cases.Mon, 31 Mar 2025 00:00:00 GMTReacthttps://alexmlewis.com/writing/why-returning-cleanup-functions-in-useeffect-matters-in-react/https://alexmlewis.com/writing/why-returning-cleanup-functions-in-useeffect-matters-in-react/React’s useEffect hook is one of the most powerful and commonly used features in functional components. It enables side effects like data fetching,…Fri, 28 Mar 2025 00:00:00 GMTReacthttps://alexmlewis.com/writing/a-guide-to-setting-up-vercel-log-storage-in-aws-s3/https://alexmlewis.com/writing/a-guide-to-setting-up-vercel-log-storage-in-aws-s3/Vercel retains logs for only 24 hours. This guide sets up a log drain to AWS S3 so you can store, query, and analyze them long-term with lifecycle policies, Lambda, and Athena.Sat, 25 Jan 2025 00:00:00 GMTInfrastructurehttps://alexmlewis.com/writing/enhancing-retrieval-augmented-generation-with-xml-prompting/https://alexmlewis.com/writing/enhancing-retrieval-augmented-generation-with-xml-prompting/In my current role, I’ve been working on a Retrieval-Augmented Generation (RAG) system designed to provide safe, reliable personal finance guidance. Given…Wed, 08 Jan 2025 00:00:00 GMTRetrievalhttps://alexmlewis.com/writing/one-thing-cursor-claude-and-the-mocking-struggle/https://alexmlewis.com/writing/one-thing-cursor-claude-and-the-mocking-struggle/As someone who spends a lot of time coding, I rely heavily on Cursor as my daily IDE, and I most often use Claude 3.5 Sonnet as my preferred model for…Tue, 07 Jan 2025 00:00:00 GMTDeveloper Toolshttps://alexmlewis.com/writing/one-thing-kneading-a-new-hobby/https://alexmlewis.com/writing/one-thing-kneading-a-new-hobby/I’m kicking off a new blogging experiment I’m calling “One Thing.” Each day, I plan to share one thing I learned, big or small, tech-related or totally…Mon, 06 Jan 2025 00:00:00 GMTPersonalhttps://alexmlewis.com/writing/automating-meeting-note-management-with-krisp-zapier-google-drive-and-notion/https://alexmlewis.com/writing/automating-meeting-note-management-with-krisp-zapier-google-drive-and-notion/An automated workflow for meeting notes using Krisp, Zapier, Google Drive, and Notion. Capture transcripts, save them to cloud storage, and sync them into a Notion database with AI summaries.Thu, 02 Jan 2025 00:00:00 GMTAutomationhttps://alexmlewis.com/writing/creating-a-blog-with-gatsbyjs-part-two/https://alexmlewis.com/writing/creating-a-blog-with-gatsbyjs-part-two/Create a blog with GatsbyJSFri, 22 Dec 2017 00:00:00 GMTDeveloper Toolshttps://alexmlewis.com/writing/creating-a-blog-with-gatsbyjs-part-one/https://alexmlewis.com/writing/creating-a-blog-with-gatsbyjs-part-one/Create a blog with GatsbyJSFri, 15 Dec 2017 00:00:00 GMTDeveloper Tools