Alex Lewis
I build applied-AI systems and the developer tooling around them. This site is my notebook: essays and rough notes on agents, evaluation, and shipping software that works, plus whatever else I’m turning over.
Now
A snapshot of what I’m spending time on lately. Where my head is right now, updated when it changes. Read the full /now →
Recently tended
Recently
All 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.
- Ground-Truthing Your LLM Judge: Does Your Eval Actually Track Reality?
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.
- 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.
- How this site is built
- I Built 50 AI Skills for the Parts of My Day I Never Got 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.
- 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.
- Reward Engineering and Evaluation
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…
- 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…
- Why Static Prompts Fail and How Probabilistic Selection Fixes It
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…
Wander by topic
All topics →- Agents 7
- Developer Tools 7
- Evaluation 4
- Retrieval 4
- React 2
- Astro 1
- Automation 1
- Infrastructure 1
There are projects I’ve written up, more about me, and my resume. The feed is at /rss.xml.