Hey there,

At DevFest Alicante last week two things struck me:

1. the talks on systems were timeless, a lot of deterministic / non-AI things.

2. the AI parts on the other hand kept coming back to one question:

How do you trust what the model produced?

Alan Buscaglia (Gentleman Programming): "Human criteria has never been worth as much as it is now"

That's what we're working through live tomorrow.

1. Free live session: Deterministic systems on top of stochastic LLMs

Wednesday 21 October, 15:00 CEST. Juanjo and I take one engineering question, work it through in code, then answer yours. LLMs are probabilistic; your validation, state, and business rules shouldn't be.

A couple of slides, and a cool live demo where we classify customer refunds in real time. 😎

Save your seat →

Can't make it? Our Slack is now focused on agentic AI. Bring your questions there.

2. Less AI than you'd expect

I cancelled my paid bookkeeping tool (incomplete, sluggish) and replaced it with ~2,000 lines of Python.

Mapping the workflow first showed only one step needed a model: reading supplier invoices, with a human approving every row. VAT, numbering and immutable outgoing invoices stay plain code with tests.

Read the design decisions. Video on the invoice scanner coming soon.

This is how I consult for small businesses as well: solve the right problem first, the simplest way, AI only where it pays off.

If you know an SMB stuck on manual, spreadsheet-heavy work, I'd appreciate the intro.

3. Lost a Claude Code session? I built a Rust CLI for that

claude --resume only lists sessions for the current directory. I'd forgotten where I ran one, so I built ccfind: full-text search across all Claude Code and Codex history, ranked, with the command to resume. 539 transcripts, 722 MB, ~0.6 seconds.

Python dev curious about Rust? Jim Hodapp and I write the Scripter to Rust newsletter.

Latest edition: why Pythonistas start thinking about where data actually lives.

4. "This worked in this case, and this is why"

Real Python covered my design patterns article I wrote around commitgraph.app, the app that keeps me accountable.

I especially liked hearing that my articles hitting the right balance:

"Most stuff on the web that's about coding is about this is what this library does. There's very, very little advice on like structural stuff... He doesn't come across as this is the answer to everything. It was like, 'Yeah, this worked in this case, and this is why I did this.'"

That's what I want every post and video to be.

Check it out here

Part II coming. If you have design + architecture challenges; let me know where you struggle (or are curious) so I can create more helpful content on my blog + YouTube channel.

5. Something lighter: book quotes in Spanish

Given Opus 5.5 is really good at piecing together tools and video editing, I started @lo.subraye

One or more inspiring book quotes a day as Shorts.

Send me a book quote and I'll credit you in the description (if you want). Would like to see this in English, let me know as well.

Also, if you're interested in this for your own content engine, reply and I can help you set it up.

See you tomorrow at 15:00 CEST?

Register for the live session →

Bob

P.S. I'd love to hear what you're building. Reply here or ping me on Slack.